RevisionC-Developmentofconceptofcompressorforcommercialvehicle

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Revision C- Development of concept of compressor for commercial vehicle
Preprint · October 2019
DOI: 10.13140/RG.2.2.22090.31685
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Master Thesis
Development of
concept of commercial
vehicle compressors

ABSTRACT
Development of concept of compressor for commercial vehicle involve process of
designing a model of a real system and conducting experiment with it for the purpose of
understanding its functional behaviour. An air compressor is used for generating air pressure for
the functioning of the air brake system or, more formally, a compressed air brake system, is a
type of friction brake for vehicles in which compressed air pressing on from piston is used to apply
the pressure to the brake pad needed to stop the vehicle. Air brakes are used in large heavy
vehicles, particularly those having multiple trailers which must be linked into the brake system,
such as trucks, buses, trailers, and semi-trailers in addition to their use in railroad trains.
The air compressor is a part of air braking system which consists of compressor, service
brakes, parking brakes, a control pedal, and an air storage tank. For the parking brake, there is a
disc or drum brake arrangement which is designed to be held in the 'applied' position by spring
pressure. Air pressure must be produced to release these "spring brake" parking brakes. For the
service brakes (the ones used while driving for slowing or stopping) to be applied, the brake pedal
is pushed, routing the air under pressure (approx. 100–120 psi or 690–830 kPa) to the brake
chamber, causing the brake to be engaged.
The air compressor draws filtered air from the atmosphere and forces it into high-pressure
reservoirs at around 120 psi (830 kPa). Most heavy vehicles have a gauge within the driver's
view, indicating the availability of air pressure for safe vehicle operation, often including warning
tones or lights. Setting of the parking/emergency brake releases the pressurized air in the lines
between the compressed air storage tank and the brakes, thus allowing the spring actuated
parking brake to engage. A sudden loss of air pressure would result in full spring brake pressure
immediately.
A compressed air brake system is divided into a supply system and a control system. The
supply system compresses, stores and supplies high-pressure air to the control system as well
as to additional air operated auxiliary truck systems (gearbox shift control, clutch pedal air
assistance servo, etc.
This Thesis have two authors:
1) Rishabh Verma – S174669
2) Rachit Laharia – S174670
Page 2 of 93

KEYWORDS
A
Air Brakes
Airflow
B
Bore
Belt Drive
C
Cooling
Connecting Rod
Crank Radius
Con Rod Angle
Clearance Volume
D
Displacement
Delivery valve
Dead Room
E
Energy saving system
Economy
F
Fuel Efficiency
G
Gear Driven
Gas Constant
H
Heat Transfer
Humidity
I
Indicated Power
Inlet Pressure
L
load
M
Mounting
Mass flow Rate
O
Outlet Temperature
Operating Pressure
P
Polytropic Index
Port Details
Peak Pressure
Power consumption
Pump up Time
R
Resultant Torque
Rotary type Compressor
S
Stroke
Suction
T
Through Drive
V
Volumetric Efficiency
W
Weight
Working speed
Page 3 of 93

Contents
1 INTRODUCTION TO BASICS OF A PISTON CYLINDER COMPRESSOR ........... 8
1.1 Positive displacement machine (Rachit Laharia) ............................................... 8
1.1.1 Rotary or Screw Type (Rachit Laharia) ....................................................... 9
1.1.2 Reciprocation Type (Rachit Laharia & Rishabh Verma) ............................ 10
2 LITERATURE SURVEY ON EXISTING DESIGNS OF COMPRESSORS FOR
COMMERCIAL VEHICLES ..................................................................................... 21
2.1 Introduction (Rishabh Verma) ........................................................................... 21
2.2 Components of a commercial vehicle compressor (Rishabh Verma) ............... 23
2.2.1 Cylinder Head Assembly............................................................................ 23
2.2.2 Cylinder Assembly ..................................................................................... 24
2.2.3 Piston Assembly ........................................................................................ 24
2.2.4 Connecting Rod Assembly ........................................................................ 24
2.2.5 Crankcase Assembly ................................................................................. 24
2.3 Basic piston cylinder compressor terminology (Rishabh Verma). ..................... 25
2.3.1 Intake Valve & Delivery Valve .................................................................... 25
2.3.2 Bore & Stroke ............................................................................................. 28
2.3.3 Clearance volume and swept volume ........................................................ 28
2.3.4 Discharge Pressure, Suction pressure and Compression Ratio ............... 29
2.3.5 Free Air Delivery (FAD).............................................................................. 30
2.3.6 Indicated power (IP)................................................................................... 30
2.3.7 Power consumption ................................................................................... 30
2.3.8 Indicated torque ......................................................................................... 31
2.3.9 Volumetric efficiency .................................................................................. 31
2.4 Performance parameters of compressor (Rachit Laharia) ................................ 31
2.4.1 Pump up time ............................................................................................. 31
2.4.2 Delivery air temperature............................................................................. 32
2.4.3 Power ......................................................................................................... 32
2.4.4 Valve Lift .................................................................................................... 32
2.4.5 Back flow during discharge and suction .................................................... 33
2.4.6 Head Volume ............................................................................................. 33
Page 4 of 93

2.5 Technical comparison (for the purpose of benchmarking and getting technical
know-how.) (Rishabh Verma & Rachit Laharia) ................................................ 34
2.5.1 Benchmarking process definition: -............................................................ 34
3 POSSIBLE APPLICATION OF COMPRESSOR IN VEHICLE ............................... 39
3.1 Introduction (Rachit Laharia) ............................................................................. 39
3.2 Air Braking System (Rishabh Verma & Rachit Laharia) .................................... 39
3.2.1 Air Dryer ..................................................................................................... 39
3.2.2 Multi Circuit Protection valve ..................................................................... 41
3.2.3 Air Tank (Reservoir)................................................................................... 42
3.2.4 Dual Brake Valve ....................................................................................... 43
3.2.5 Brake chamber and Spring Brake Actuator. .............................................. 44
3.3 Trailer control system (Rishabh Verma & Rachit Laharia) ................................ 45
3.3.1 Trailer air supply control............................................................................. 45
3.3.2 Trailer air tanks .......................................................................................... 46
3.3.3 Trailer control valve .................................................................................... 46
3.4 Suspension system (Rachit Laharia) ................................................................. 47
3.5 Emergency alert system (Rishabh Verma) ........................................................ 48
3.6 Tyre Inflator (Rishabh Verma) ........................................................................... 49
3.7 Through Drive (Rishabh Verma)........................................................................ 50
4 SELECTION OF THE RELEVANT COMPRESSOR APPLICATION AND
DEVELOPMENT OF STRATEGY OF PROBLEM SOLVING. ............................... 51
4.1 Application of compressor for air braking system (Rachit Laharia) ................... 51
4.1.1 Design Input capturing of Air Braking System ........................................... 51
4.2 Application of compressor for Through drive Input capturing (Rachit Laharia) . 51
4.2.1 Design Input capturing of Through Drive System ...................................... 52
4.3 Problem Solving Strategy (Rishabh Verma & Rachit Laharia) .......................... 52
4.3.1 Problem and failures description ............................................................... 52
5 DEVELOPMENT OF THE ALGORITHM FOR CALCULATION OF A
COMPRESSOR ...................................................................................................... 54
5.1 Mathematical modelling of compressor (Rishabh Verma & Rachit Laharia) ..... 54
5.1.1 Bore (d):- It is the inner diameter of the cylinder where the piston moves.55
5.1.2 Stroke (S):-................................................................................................. 55
Page 5 of 93

5.1.3 Displacement (D):- ..................................................................................... 56
5.1.4 Air Flow (V): - ............................................................................................. 56
5.1.5 Volumetric Efficiency (λ):- .......................................................................... 56
5.1.6 Clearance Volume (Vc): - ........................................................................... 57
5.1.7 Stroke to bore ratio: - ................................................................................. 57
5.1.8 Air intake per min(V1):- ............................................................................... 57
5.1.9 Mass flow rate (m): - .................................................................................. 58
5.1.10 Crank Radius (r): - ..................................................................................... 58
5.1.11 Outlet Temperature (T2): -.......................................................................... 59
5.1.12 Indicated power (Pi): -................................................................................ 59
5.1.13 Belly inner dia. (Øbi): - ............................................................................... 59
5.1.14 Belly outer dia. (Øbo): - .............................................................................. 60
5.1.15 Connecting rod length (l): - the connecting rod angle of less the 16° is
considered good. ....................................................................................... 60
5.1.16 Connecting rod angle (Ө):- ........................................................................ 60
5.2 Stack-up calculation (Rachit Laharia) ................................................................ 61
5.3 CAD/CAM & Material selection (Rishabh Verma) ............................................. 62
5.3.1 Designing and material selection of aluminium parts (commodity 1) ........ 64
5.3.2 Designing and material selection for sealants (commodity 2) ................... 75
5.4 losses in a commercial vehicle compressor (Rishabh Verma) .......................... 78
6 ANALYSIS OF THE RESULTS AND VERIFICATION ............................................ 80
6.1 Introduction (Rishabh Verma) ............................................................................ 80
6.2 Design Validation (Rachit Laharia & Rishabh Verma) ...................................... 80
6.2.1 Functional test or performance test- .......................................................... 80
6.2.2 Pressure leak test ...................................................................................... 81
6.2.3 Endurance Test .......................................................................................... 82
6.3 Tightening torque verification (Rachit Laharia) .................................................. 83
7 CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE APPLICATIONS ... 84
7.1 Conclusion (Rishabh Verma & Rachit Laharia) ................................................. 84
7.2 Recommendation for future (Rachit Laharia & Rishabh Verma) ....................... 84
8 SUMMARY (Rachit Laharia) ................................................................................... 86
Page 6 of 93

LIST OF IMPORTANT SYMBOLS AND ABBREVIATIONS
V - Displacement
A - Area(Bore)
S - Stroke
D - Bore diameter
π - Greek letter Pi(3.14)
v o - FAD
N - Compressor Speed (rpm)
b - Number of cylinders
CR - Compression Ratio
Pad - Absolute Discharge Pressure
Pai - Absolute Inlet Pressure
Pi - bolt preload (N)
T - Bolt installation torque (Nm).
K - torque coefficient- 0.22 for zinc plated bolts.
D - bolt nominal shank diameter (m)
Page 7 of 93

1 INTRODUCTION TO BASICS OF A PISTON CYLINDER COMPRESSOR
(RACHIT LAHARIA)
Building a concept model for any project may be a challenging, yet interesting task. A
thorough understanding of the underlying scientific concepts is necessary and a mentor with
expertise in the project is invaluable. It is also best to work as part of a team to provide more
brainstorming power. In industry and engineering, it is common practice for a team of people to
work together in building a model, with the individual team members bringing different areas of
expertise to the project [1]. To start the concept modelling initial basics are required to be
understood thoroughly, before applying them to the mathematical modelling. Once the model has
been developed and applied to the problem, the resulting model solution must be analysed and
checked for accuracy. It may be required to modifying the model for obtaining reasonable
outcome. This refining process should continue until obtaining a model that agrees as closely as
possible with the real-world observation.
A reciprocating compressor consists of a crankshaft (driven either by a gas engine,
electric motor, or turbine) attached to a connecting rod, which transfers the rotary motion of the
crankshaft to the piston. The piston travels back and forth in a cylinder [1]. The piston acting
within the cylinder then compresses the air contained within that cylinder. Air enters the cylinder
through a suction valve at suction pressure and is compressed to reach the desired discharge
pressure. When the air reaches the desired pressure, it is then discharged through a discharge
valve. Desired discharge pressure can be reached through utilization of either a single or double
acting cylinder. In a double acting cylinder, compression takes place at both the head end and
crank end of the cylinder. The cylinder can be designed to accommodate any pressure or
capacity, making the reciprocating compressor the most popular in the automobile industry [2].
These compressors can be classified as: -
1.1 Positive displacement machine
1.2 Dynamic impulse machine
1.1 Positive displacement machine
A machine where a fluid (air) is physically trapped between two relatively moving
components and forced to occupy lower volume and hence increasing the pressure of the fluid,
this type of machines is called Positive displacement Machine. The function of a compressor is
to take a definite quantity of fluid and deliver it at a required pressure, and most often air. To do
this, mechanical work must be supplied to the air compressor, by an electric motor, turbine or
engine. The work done by the air compressor on the air, and this is called as the indicated work
of the compressor.
Page 8 of 93

Figure 1:1: A typical air compressor
Positive displacement air compressors are of two type: -
1.1.1 Rotary or Screw Type
1.1.2 Reciprocation Type
1.1.1 Rotary or Screw Type
Figure 1:2: Rotary type air compressor
Rotary type air compressor is a machine in which the compression is affected by a
rotating vane or impeller that imparts velocity to the flowing air to give it the desired pressure. [3]
The rotary or screw type air compressor has the below properties: -
• Mass flow-rate for these compressors are higher due to continuous operation,
• Lower efficiency and pressure
• Commonly used in smaller vehicles,
• light in weight and Small in size,
• Designing of this type of air compressor is simple,
• Commonly used in smaller vehicles,
Page 9 of 93

Rotary/Screw air compressor of positive displacement type use two meshing helical
screw, which are called rotors, to compress the fluid (air). They are commonly used in vehicles
or engines to replace the piston-cylinder type compressor or the reciprocating type compressor
where a large volume of high pressure is required and where heavyweight and the large size is
not affordable.
Rotary screw air compressors are easy to maintain and operate. Capacity control for
these compressors is accomplished by variable speed and variable compressor displacement.
For the latter control technique, a slide valve is positioned in the casing. As the compressor
capacity is reduced, the slide valve opens, bypassing a portion of the compressed air back to the
suction. Advantages of the rotary screw compressor include smooth, pulse free air output in a
compact size with high output volume over a long life [4].
The oil free rotary screw air compressor utilises specially designed air ends to compress
air without oil in the compression chamber yielding true oil free air. Oil free rotary screw air
compressors are available as air cooled and water cooled and provide the same flexibility as oil
flooded rotaries when oil free air is required. [4]
1.1.2 Reciprocation Type
A reciprocating air compressor is a machine that compresses fluid(air) by a piston
reciprocating inside a cylinder.
The reciprocating type air compressor has the below properties: -
• Due to the pulsating operation, these compressors have a low mass flow rate,
• Higher efficiency,
• Higher pressure ratio,
• Heavy in weight and big in size,
• Designing for this type of the compressors is very complex,
• Commonly this type of design is adapted for commercial vehicles,
Page 10 of 93

Figure 1:3: Reciprocating air compressor (Single acting)
A reciprocating air compressor consists of: -
• Cylinder arrangement.
• Piston Moving in a cylinder.
• Connecting rod arrangement
• Intake and exhaust valve
• crank
• Oil arrangement to reduce friction
Figure 1:4: Piston-moving inside the cylinder
Page 11 of 93

Reciprocating compressors are used in commercial automotive with air brake system.
They are in use for more than six decades. Development of a compressor requires an insight into
the design parameters and their effects on performance, cost and life of the compressor.
Reciprocating air compressors are positive displacement machines that they increase
the pressure of air by reducing its volume. This means they are taking in successive volumes of
air which is confined within a closed space and elevating this air to a higher pressure. The
reciprocating air compressor accomplishes this by a piston within a cylinder as the compressing
and displacing element. Single-stage and two-stage reciprocating compressors are commercially
available. Single-stage compressors are generally used for pressures in the range of 500 kPa to
900 kPa. Two-stage compressors are generally used for higher pressures in the range of 900
kPa to 1800 kPa. The reciprocating air compressor is single acting when the compression is
accomplished using only one side of the piston. A compressor using both sides of the piston is
considered double acting. Load reduction is achieved by unloading individual cylinders. Typically,
this is accomplished by throttling the suction pressure to the cylinder or bypassing air either within
or outside the compressor. Capacity control is achieved by varying the speed in engine-driven
units through fuel flow control. Reciprocating air compressors are available either as air-cooled
or water-cooled in lubricated and non-lubricated configurations, may be packaged, and provide
a wide range of pressure and capacity selections [1].
A reciprocating compressor consists of a crankshaft (driven by a gas engine, electric
motor, or turbine) attached to a connecting rod, which transfers the rotary motion of the crankshaft
to the piston. The piston travels back and forth in a cylinder. The piston acting within the cylinder
then compresses the air contained within that cylinder. Air enters the cylinder through a suction
valve at suction pressure and is compressed to reach the desired discharge pressure. When the
air reaches the desired pressure, it is then discharged through a discharge valve. Desired
discharge pressure can be reached through utilisation of either a single or double acting cylinder.
In a double acting cylinder, compression takes place both at the head end and crank end of the
cylinder. The cylinder can be designed to accommodate any pressure or capacity, thus making
the reciprocating compressor the most popular in the gas industry. [2]
Reciprocating compressor can be classified into two types:
1.1.2.1 Single-acting compressor
1.1.2.2 Double-acting compressor
1.1.2.1 Single-acting compressor: -
and cylinder.
Single-Acting compressor is a machine which compresses air in only one end of piston
Page 12 of 93

1.1.2.2 Double-acting compressor: -
Double-acting compressor is a machine where the air is compressed at both ends of
piston and cylinder. Both the reciprocating air compressor can be further also classified into 3
parts.
Figure 1:5: Double-acting compressor
Reciprocating air compressor types can be also defined as: -
1.1.2.3 Reciprocating air compressor without clearance volume
1.1.2.4 Reciprocating air compressor with clearance volume
1.1.2.5 Multi-stage compressor
1.1.2.6 Oil free compressor
1.1.2.3 Reciprocating air compressor without clearance volume: -
The cycle of operation of a reciprocating air compressor is shown on a p-V diagram. It is
known as an indicator diagram for the compressor [5].
The cycle comprises of three processes
1.1.2.3.1) d-a: Induction stroke
1.1.2.3.2) a-b: Compression stroke
1.1.2.3.3) b-c: Delivery stroke
d-a: Induction stroke: -
Intake valve opens, while the exhaust valve closed. Atmospheric air is drawn into the
cylinder at constant pressure, p1 and T1. Ideally, there is no heat loss to the surrounding from
the air [5].
Page 13 of 93

a-b: Compression stroke: -
Both intake and exhaust valves closed. The air is compressed according to the polytropic
law, pV n =constant. Its pressure is increased from p1 to p2. The temperature is also increased from
T1 to T2. [5]
b-c: Delivery stroke: -
Intake valve closed while the exhaust valve opens. The compressed air is pushed out of
the cylinder at constant pressure, p2 and T2. There is no heat loss from the air to the surroundings.
[5]
Figure 1:6: p-V diagram for a reciprocating compressor without clearance
Analysis of the cycle [5]
The area under the p-V diagram represents the net or indicated work done on the air per
cycle Indicated work/cycle,
= area abcd = (area abef + area bc0e) – area ad0f
Work input = p 2V b − p 1 V a
+p
n−1 2 V b − p 1 V a
Work input =
n
n−1 (p 2V b − p 1 V a )
Indicated work per cycle =
n
n−1 (p 2V b − p 1 V a )
1.1.2.4 Reciprocating air compressor with clearance volume
The compressor with spacing between the top of the piston and the valve’s heads when
the piston is at the end of the delivery stroke is reciprocating compressor with clearance volume.
The cycle for this type of comprises four processes. [5]
Page 14 of 93

Process Description
Figure 1:7: p-V diagram for a reciprocating compressor with clearance
c-d: Expansion stroke: -
Piston begins the induction stroke. The compressed air occupying the clearance volume
expands according to the polytropic law until p and T reduce to p1 & T1. Ideally, no heat transfer
from air to the surrounding.
d-a: Induction stroke: -
Inlet valve open. Fresh air is induced into the cylinder at constant p & T. The volume of
air induced is Va–Vd. No heat transfer from air to the surrounding.
a-b: Compression stroke: -
Both valves closed. Induced air is compressed according to pVn=c, until the pressure
and temperature increases to p2 and T2. No heat transfer from air to the surrounding.
b-c: Delivery stroke: -
The exhaust valve opens. The compressed air is delivered out at constant pressure p2
and T2. No heat transfer from the air to surroundings. Air Compressors with Clearance.
Note: At the end of the delivery stroke, the clearance volume is filled with compressed air at p2
and T2. The cycle is then repeated.
1.1.2.5 Multistage Compressor
The air is compressed in more than one cylinder (or stage) to the desired pressure, p2.
After the first stage of compression, the fluid is passed into a smaller cylinder in which the gas is
compressed to the required final pressure. If the machine has two stages, the gas will be
delivered at the end of this stage, but it also could be delivered to a third cylinder for higher
pressure ratio.
Page 15 of 93

Figure 1:8: Indicator diagram for a 2-stage machine
Figure 1:9: p-V diagram for effect of increase delivery pressure on the volume of fresh air
induced
Figure 1:10: p-V diagram for effect of increase delivery pressure on the volume of fresh air
induced
Page 16 of 93

The condition for minimum work is that the compression process should be isothermal.
The temperature after compression is:
T 2 = T 1 (p 2 /p 1 ) n-1/n
Delivery temperature increases with the pressure ratio.
η v = 1 − V c
V c
{( p 2
p 1
) 1/n − 1}
It can be seen that as the pressure ratio increases the volumetric efficiency decreases.
The reciprocating compressor is probably the best known and most widely used of all
compressors. It consists of a mechanical arrangement in which reciprocating motion is
transmitted to a piston, which is free to move in a cylinder. The displacing action of the piston,
together with the inlet valve or valves, causes a quantity of gas to enter the cylinder where it is in
turn compressed and discharged; Action of the discharge valve or valves prevents the backflow
of gas into the compressor from the discharge line during the next intake cycle. When the
compression takes place on one side of the piston only, the compressor is said to be a single
acting. The compressor is double acting when compression takes place on each side of the
piston. Configurations consist of a single cylinder or multiple cylinders on a frame. When a single
cylinder is used or when multiple cylinders on a common frame are connected in parallel, the
arrangement is referred to as a single-stage compressor. When multiple cylinders on a common
frame are connected in series, usually through a cooler, the arrangement is referred to as a
multistage compressor. Reciprocating compressor is classified into many categories with respect
to cylinder arrangement and drive methods. [5]
1.1.2.6 Oil free reciprocating compressor [5]
Oil free reciprocating compressors are broadly classified into two types. One is a trunk
piston type (Engine or Automotive piston type) and another is cross head type. The cross sections
of both compressors are shown below. The cross-head type compressor details are collected
from Bloch & Hoofer (1996). Fig. 1.10 Trunk piston compressor Fig. 1.11 Crosshead type piston
compressor.
Oil-free piston compressors have piston rings of PTFE or carbon; alternatively, the piston
and cylinder wall can be toothed as on labyrinth compressors. Larger machines are equipped
with a crosshead and seals on the gudgeon pins, ventilated intermediate piece to prevent oil from
being transferred from the crankcase and into the compression chamber. Lubricants less designs
have piston arrangements similar to lubricant-free versions, but do not have lubricant in the
crankcase. Generally, these machines have a grease pre-packed crankshaft and connecting rod
bearings.
Page 17 of 93

Figure 1:11: Trunk piston compressor
Figure 1:12: Crosshead type piston compressor
Single-Frame straight-line reciprocating compressors are horizontal or vertical doubleacting
compressors with one or more cylinders in line in a single frame having one crank throw,
one connecting rod and crosshead. They may be belted or direct-connected motor-driven.
V or Y-type reciprocating compressors are two-cylinder, vertical double-acting machines
in which the compressor cylinders are arranged at some angle, using 45° from the vertical, and
are driven from a single crank.
Semi-Radial reciprocating compressors are similar to the V- or Y-type except that, in
addition to the double-acting compressor cylinders arranged at an angle from the vertical,
Page 18 of 93

horizontal double-acting cylinders are also arranged on each side, all operated from a single
crankpin.
There are many applications of industrial compressors in which the oil in the gas stream
cannot be tolerated. The oil-free compressed air is essential in industries such as the food
industry, the brewing industry and the packaging (Pharmaceuticals) industry as well as in some
industrial air control systems.
But even in general industry or manufacturing, there may be reasons to consider reducing
the amount of lubricating oil used in the compressor cylinders. The excess oil can build up in the
discharge valve port 10 areas, and even the best premium grades of compressor oil will oxidize
when subjected to high temperatures. These oils may eventually form gummy or sludge-like
deposits, which reduce the performance of a compressor and in some cases lead to fires in the
air system if they are allowed to build up. For these and other reasons, non-lubricated operation
has become increasingly popular.
The oil free piston compressors subjected to a greater number of premature bearing
failures in the transmission system. In this design, it is not possible to have sliding bearings due
to the absence of oil for lubrication. Unlike in oil flooded machines, cylindrical roller bearings are
not possible to implement due to the space constraint and difficulty in self lubrication.
Meece et al., (1974) described the designing of oil-less reciprocating, rotary vane,
diaphragm compressors and pumps. Since the widespread use of oil-less air is relatively new;
particular emphasis will be stressed on the design features and considerations, which distinguish
the oil less unit from a lubricated unit. The media being pumped is not exposed to an oil lubricant.
The piston pin needle bearings are contained in the connecting rod and are sized to a slip fit over
the piston pin. Since the needle bearings have very limited grease storage capacity, the
connecting rods are usually designed with an integral grease reservoir between the bearings.
Other than these compressors there is dynamic impulse type compressor, that is nonpositive
displacement compressor. And are not used for commercial vehicle purpose.
They can be one of below: -
i) Centrifugal
ii) Centrifugal mixed-flow
iii) Centrifugal axial flow
The centrifugal air compressor is a dynamic compressor which depends on transfer of
energy from a rotating impeller to the air. Centrifugal compressors produce high-pressure
discharge by converting angular momentum imparted by the rotating impeller (dynamic
displacement). In order to do this efficiently, centrifugal compressors rotate at higher speeds than
Page 19 of 93

the other types of compressors. These types of compressors are also designed for higher
capacity because flow through the compressor is continuous. Adjusting the inlet guide vanes is
the most common method to control the capacity of a centrifugal compressor. By closing the
guide vanes, volumetric flows and capacity are reduced. The centrifugal air compressor is an oil
free compressor by design. The oil lubricated running gear is separated from the air by shaft
seals and atmospheric vents.
Page 20 of 93

2 LITERATURE SURVEY ON EXISTING DESIGNS OF COMPRESSORS
FOR COMMERCIAL VEHICLES
2.1 Introduction
During our thesis and internship, we focused on the aim to develop an air compressor for
a commercial vehicle. So, this thesis will be focusing more about the study and designing of
reciprocating compressors, which is majorly used by all the commercial vehicle for the air braking
system.
Figure 2:1: Commercial Vehicle
The designs are based on the compressed air requirement by vehicle for its functionality.
More consumption means a bigger compressor. For the beginning let’s try to understand the
basic components and functionality of compressor installed in a commercial vehicle. The
compressor is a very important and integral part in the vehicle, as compressed gas is used for
the air braking system, to inflate tyres of the vehicle, also in-service stations to operate pneumatic
tools. Considering especially commercial vehicles, compressed air is a constant requirement to
operate important vehicle control systems such as air Braking system, and a few others like
suspension, trailer control systems etc. The braking system is a very crucial and important system
for a vehicle and here comes the requirement to mount a compressor on the vehicle itself to
generate enough compressed air at any given instance. And mounting it on the vehicle means
we cannot use regular compressors used in industry.
In this part, we will discuss different aspects of design and environmental parameters,
the existing design used by most of the OEMs like Fuso, Hino, Daimler, Volvo. Using this as the
study we did the mathematical modelling and 3D- modelling and perform analysis on important
aspects to design and develop a concept of more efficient and a powerful compressor with some
unique selling propositions USP’S.
Page 21 of 93

Figure 2:2: Typical commercial vehicle compressor fluid flow
Figure 2:3: Air braking system in a commercial vehicle
First step to study the existing design available in the market is to know the input and
output of the product and the reason for it, compressor requires fluid flow of atmospheric air to
compress the small amount of air at a high pressure and fluid flow of oil to achieve frictionless
movement of internal parts (Fig. 2.2) showing the fluid flow for the functionality of the compressor.
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Secondly, the study of mounting of the compressor on the vehicle is also a parallel informant, it
aware us about the design parameters such as vibration acting on compressor due to engine
reciprocation or chassis mounting. (Fig. 2.3) shows the compressor position on a truck.
For our study, we used 6 Asian market compressor and 6 European market compressors
2.2 Components of a commercial vehicle compressor
Figure 2:4: Components of a Commercial Vehicle reciprocating compressor of single stage
Components of a Commercial Vehicle reciprocating compressor are sub categorised in
below levels. [5]
2.2.1 Cylinder Head Assembly
2.2.2 Cylinder Assembly
2.2.4 Connecting Rod Assembly
2.2.5 Crankcase Assembly
2.2.3 Piston Assembly
2.2.1 Cylinder Head Assembly
Cylinder head assembly provides the inlet and outlet of the air for the compression. It
also provides room for air cooling. Cylinder head assembly intakes a very low-pressure air say
(1 bar) and then pass this air to the cylinder block through the inlet reed valve. The inlet reeds
are designed to ensure one-way flow for the incoming air and restrict the loss of pressure during
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delivery stroke. To deliver the compressed air the cylinder head assembly is also installed with
the delivery reed valve this valve is specially designed to ensure the deliver air reaches the
delivery port only in when the required outlet pressure is reached say (8bar).
Cylinder head assembly are categories in 2 types: -
2.2.1.1 Air Cooled Cylinder Head Assembly: -
Air cooled cylinder head cool’s the delivery air by heat transfer process using fins and
without any coolant circuit.
2.2.1.2 Water Cooled Cylinder Head Assembly: -
circuit.
Water cooled cylinder head cools the delivery air by heat transfer process using coolant
2.2.2 Cylinder Assembly
Cylinder assembly provides the path for the piston movement, it is used as a space for
the compression of the air and also includes the clearance space so the piston does not strike
damage the reed valves. The volume inside the cylinder to compress the air is a major factor for
effecting the air flow of the compressor.
2.2.3 Piston Assembly
A piston assembly is a subassembly part of a cylinder-piston compressor, which motion
is constrained by the cylinder, its purpose is to transfer force from the crankshaft to expanding
gas in the cylinder and compress it to high pressure. Piston usually consists of piston rings, piston
pin and retaining rings. Piston rings are of two types of compression ring and oil control ring.
2.2.4 Connecting Rod Assembly
Conrod or a connecting rod is a link between piston and crankshaft in a reciprocating
compressor. The connecting rod linking the piston and the crankshaft converts linear motion into
rotary motion and also rotary motion to linear motion. we will target in this study to redesign a
connecting rod with lightweight, better manufacturing feasibility, better performance parameter
and cost-efficient design.
2.2.5 Crankcase Assembly
Crankcase assembly includes the cylinder, crankshaft, piston, connecting rod and case
to bind them together for the proper functioning of the component. Crankcase assembly also
provides the bearing support for the shaft to transmit the torque from one end to the required
ends. The crankcase has the oil circuit that is used to supply oil to the shaft, connecting rod and
piston for the smoother movement.
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The crankshaft is used to drive torque from either belt or gear attached to it and the
engine of the vehicle. It is also used to transmit this torque to the fuel pump of steering pump to
drive it. Crankcase provides bearing for the free movement of the crankshaft.
All these sub-assembly parts work together to serve as a compressor unit of a
commercial vehicle.
2.3 Basic piston cylinder compressor terminology.
2.3.1 Intake Valve & Delivery Valve [5]
A compressor valve is a device that controls the inward flow of lower pressure gas at
atmospheric conditions and the outward flow of higher-pressure gas from a reciprocating
compressor cylinder. Normally these valves open and close automatically, solely governed by
the pressure differential in the cylinder and the intake or exhaust line pressure. There is at least
one suction valve and one discharge valve for every compression chamber. Each valve opens
and closes in every cycle. A valve used in a compressor operating at 1200 rpm for 12 hours a
day and 280 days a year, opens and closes 72,000 times per hour or 864,000 times per 12 hours
in a day or 241,920,000 times per year.
There are essentially two requirements to be met by a valve, (a) the valve must be
efficient, and (b) the valve must be durable and quiet in service. The above criteria can be refined
and can include both the aerodynamic flow efficiency and the volumetric efficiency. Under
durability, the maintenance free operation for over several thousand hours plus relative ease in
servicing and repair can also be included.
There are different kinds of compressor valves: plate or disc valves, ring valves, channel
valves, feather valves, poppet valves, ball valves, reed and concentric valves, to name just a few.
Each design has a specific criterion with regard to the sealing element and all the other
components are designed accordingly. Most of the air compressors used in automotive braking
system use reed, disc or ring valves.
In disc valves the plate is operated by a compression ring. The ring valve is an annular
disc valve operated by a spring. Fig. 2.5 shows the opening of disc valve used on suction and
delivery sides.
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Figure 2:5: Inlet and Delivery disc valve openings
When the valve is closed, part of the valve plate or valve ring is firmly set against the seat
lands. The sealing element initially lifts off the seat land slowly but accelerates rapidly towards
the guard once spring forces are overcome.
The factors that account for the initial pressure differential between cylinder and line
pressure at valve opening that is seen on all PV-diagrams are (i) the cylinder pressure exposed
to the entire surface area of the sealing element (ii) the sticking effect of lubrication or condensate
and (iii) the spring load force.
To lift the sealing element off the seat land, a pressure differential is required across the
sealing element. The difference in area of a sealing element is normally 15% to sometimes as
high as 30% between exposure underneath (seat side) and exposure on top (guard side). Since
there is always some leakage through the closed valve plate along the seat lands, there is a
certain amount of pressure build-up in this area. Therefore, the actual pressure differential
needed to induce or cause the valve open is only 5% to 15% over the line pressure. As the sealing
element lifts off the seat lands, it accelerates rapidly against the spring load towards the guard.
The sealing element impacts against the guard causing the opening impact, at this stage the
valve is considered fully open.
Piston velocity at top or bottom dead centre is zero and increases gradually to a
maximum at the middle of its stroke. Valve velocity follows a slower path than the piston. The
flow of the gas out through the seat keeps the sealing element open. As the flow diminishes due
to the decreasing piston speed, the springs or other cushioning elements force the sealing
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element to Valve lift Inlet valve Cylinder bore Delivery valve stopper Delivery valve Cylinder bore
Valve lift return to the seat lands and close the valve on time. Preferably, the valve is completely
closed when the piston is at or near dead centre.
A reed valve is a flow actuated one-way valve. A port in the line is covered by the free
end of a thin and flexible blade whose other end is fastened so that the port is normally closed.
Pressure in the port or vacuum on the far side, will lift the blade, permitting the flow. If the pressure
reverses, it closes the blade, stopping the flow. Usually the reed valves use a single blade, but
modern versions combine four, six or eight blades, or petals, into tent-like arrays, fastened to a
multi-ported reed cage. Reed valve involves the loss of pressure, as some pressure difference is
required to open the valve. Even with this limitation, they have excellent versatility. Figure 3.3
shows the inlet and delivery valves employed in a 160-cc air cooled compressor.
Figure 2:6: Inlet and Delivery disc valve openings
Modern compressors employ reed valves because of the following features:
• Number of components required is less. So almost no wear takes place.
• The number of holes in the valve plate can be increased which will increase the
flow area. This will reduce the pressure required to open the valves, and hence
lesser pressure drop across the valves.
• Lesser assembly difficulties.
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2.3.2 Bore & Stroke [5]
Bore: - The inner diameter of the cylinder of the compressor is called bore, it is the space
inside the cylinder where the piston moves.
Stroke: - The difference(height) between top dead centre and the bottom dead centre
travelled by the piston is known as the stroke.
TDC (Top Dead centre): - The maximum top height attend by a piston during a work cycle
is known as the Top dead centre.
BDC (Bottom Dead centre): - The minimum bottom height attend by a piston during a
work cycle is known as the Bottom dead centre.
2.3.3 Clearance volume and swept volume [5]
Clearance volume (Vc): It is the volume that is available after the piston reaches the TDC.
This volume is provided in the compressor for ensuring free movement of compressor valves.
The presence of clearance volume reduces the volumetric efficiency. Stroke volume (Vs) or swept
volume is the volume corresponding to stroke.
Swept Volume: It is the amount of air displaced during a compression cycle. It is directly
proportional to the area of the bore and the stroke of the piston it can be calculated by multiplying
the area and stroke.
V = A × S
A = π 4 × d2
Figure 2:7: Terminology Diagram 1
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Clearance Volume: It is a spacing between the top of the piston and the valve’s heads
when the piston is at the end of the delivery stroke. Good quality machines have a clearance
volume of about 6%. But compressors with a clearance of 30-35% are also common. clearance
volume directly affects the efficiency of the compressor. lower the clearance volume higher the
efficiency. Clearance volume is required to meet the below-mentioned points.
• For the mechanical freedom of the moving parts.
• It reduces the noise and vibration
• It also prevents the damage to the moving parts.
Figure 2:8: Terminology Diagram 2
2.3.4 Discharge Pressure, Suction pressure and Compression Ratio
• Discharge Pressure: This is the absolute pressure of the air at an outlet (delivery)
of a compressor.
• Suction Pressure: This is the absolute pressure of the air at an inlet (Suction) to
a compressor.
• Compression Ratio: - This is the ratio of the absolute discharge pressure to the
absolute inlet pressure.
Pad = Absolute Discharge Pressure
Pai = Absolute Inlet Pressure
CR = p ad
P ai
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2.3.5 Free Air Delivery (FAD)
Free air delivery is the volume of air delivered under the conditions of temperature and
pressure existing at the compressor intake
v o (m 3 /min)
This generally taken 1.0332 kg/cm² abs & 15-degree centigrade, if an air conditioner is
not given.
If the FAD is measured at ambient conditions, i.e. p=po and T=To with compressor speed,
N (rpm), compressor type, b and number of cylinders, e, the actual volume delivered per cycle is:
-
Note:
-if single-acting, b=1
-if double-acting, b=1
v o = FAD
N = Compressor Speed (rpm)
v o =
e = Actual volume delivered per cycle
b = Number of cylinders
ύ o
N × b × e
2.3.6 Indicated power (IP)
Work energy imparted to the air per unit time is called indicated power. This power can
be obtained from the p-V diagram.
2.3.7 Power consumption
The power available at the compressor shaft to run the compressor at the desired
discharge pressure and speed is termed as the power consumption. The power imparted to the
air in the cylinder is Indicated power (IP). All the power available at the compressor shaft will not
be imparted to the air in the cylinder. The friction between the moving parts absorbs some power
and it is called friction power (FP). The FP varies with compressor speed. The load (discharge
pressure) on the compressor has a negligible effect on FP. As the speed increases FP increases.
For power absorbing machines, like compressor,
Mechanical efficiency, η = IP
BP
If the compressor gets power from I.C engines, it is convenient to take the power required
to run the compressor equal to the brake power (BP) of the compressor. The mechanical
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efficiency (Km) of any reciprocating machine will be around 0.75 to 0.8 at rated speed. For the
same speed, the 43KW power required to run the compressor decreases with decrease in mass
of air handled.
2.3.8 Indicated torque
Torque (or often called a moment) can be thought of as a “rotational force” or “angular
force” which causes a change in rotational motion. This force is defined by linear force multiplied
by a radius.
If a force is allowed to act through a distance, it does mechanical work. Similarly, if
moment is allowed to act through a rotational distance, it does work. Power is the work per unit
time. However, the time and rotational distance are related by the angular speed where each
revolution results in the circumference of the circle being travelled by the force that is generating
the torque. This means that, torque causes the angular speed to increase in doing work and the
generated power may be calculated as
P = Torque x Angular Velocity
From the torque calculation at different crank angles, it is possible to find the maximum
torque and maximum indicated power which the compressor absorbs in a cycle.
2.3.9 Volumetric efficiency
Analysis of volumetric efficiency is essential to estimate the suitability of a compressor
for a particular application. The factors affecting volumetric efficiency are
• Clearance volume (Increase in clearance volume decreases Kv)
• Discharge pressure (Increase in discharge pressure decreases Kv)
• Temperature of cylinder (Heating of the cylinder decreases Kv)
• Compressor speed (Increase in speed decreases the increase in Kv)
• Leakage (Leakage past the piston, decreases Kv, but this effect can be
neglected)
2.4 Performance parameters of compressor
The performance of the compressor can be studied by individual parameters, such as
pump up time, delivery air temperature, speed and power. [5]
2.4.1 Pump up time
Pump up time is the time required to develop a delivery pressure in a reservoir of given
volume connected to the compressor air outlet. Pump up time is important as it indicates the
volume flow rate of air inside the compressor under given operating conditions. Mainly the
clearance volume affects pump time performance in addition to the flow area available in the
cylinder head. The flow area available should not be less than the adapter inside flow area.
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2.4.2 Delivery air temperature
It is the temperature of air after compression measured at the delivery port of the cylinder
head. Delivery air temperature has two issues: 39 (i) the degree of heat generated by the
compression process and (ii) the degree of cooling of the compressor after the compression
process.
The air from the compressor is led into the air drier (Air processing unit) which purges
the air from most of the moisture. The temperature of the air that enters the air processing unit is
limited to about 70°C. This necessitates the use of long metallic finned pipelines (nearly 6 m long)
in order to allow sufficient time for cooling of air. A long pipeline complicates assembly issues on
the vehicle. Thus, a reduced delivery air temperature would reduce the need for long pipelines
and thereby simplify the problems. A high delivery air temperature increases oil carryover and
thereby further increase in the delivery air temperature due to the formation of carbon deposits
on the piston and the cylinder head. Carbon deposits on the cylinder head reduce the heat
dissipation capacity of the fins on the inner cavity of the cylinder head. Cylinder head design has
a vital influence on the delivery air temperature.
2.4.3 Power
Power is measured under three conditions:
• Loaded power: Loaded power is the power consumed by the compressor while
pumping against a pressure gradient.
• Unloaded power: Unloaded power is the power consumed while pumping to
atmosphere (with ideally no pressure gradient) through the unloaded valve. The
unloaded valve regulates the pressure against which the compressor is pumping.
Unloaded power reflects the power losses at the unloaded valve due to flow
resistance.
• No load power: No load power is the power consumed while the compressor’s
delivery is open to atmosphere. No load 40 power is indicative of the power
losses due to the flow resistance in the cylinder head of the compressor.
2.4.4 Valve Lift
It is the vertical distance travelled by the suction or discharge valve at any crank angle.
Valve lift is governed by the goal to design valves with acceptable life and uninterrupted service.
Since the plate or sealing element opens and closes with every revolution of the crankshaft,
factors such as rotating speed, operating pressure and molecular weight of the gas determine
the limits of allowable valve lift. The impact resilience of various materials used for valve plates
(steel, polymers, etc.) also has an influence on maximum acceptable valve lift. Different valve
manufacturers use more or less conservative guidelines for allowable lift for a given set of
operating conditions. Excessive valve lift can have detrimental effects on valve life, due to high-
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velocity impact forces, valve flutter, late closing, and other life deteriorating developments. Once
an acceptable valve lift is defined, the rest of the valve geometry can be selected to balance the
ratios of seat and guard area to free lift area. The diverse applications result in a variety of valve
concepts. For example, slow-speed applications favour wide-ported seats and guards and high
valve lifts, while high-speed applications require narrow ports and lower lifts would be applied.
2.4.5 Back flow during discharge and suction
Whenever the valve closes, there will be a flow of some discharged air into the cylinder.
This phenomenon is called “Back flow during discharge’ and this reduces the mass of air
discharged. Similarly, whenever the valve closes, there will be a flow of some drawn air from the
cylinder to the atmosphere. This phenomenon is called “Back flow during suction’ and this
reduces the mass of air drawn in.
2.4.6 Head Volume
The volume just above the valve plate is called ‘head volume’. It is also called plenum
chamber volume. There are two compartments in the head, suction and discharge plenum
chambers.
Discharge Head: The air is discharged into the receiver through the head volume. The
pressure in the head will not be constant, because, the mass going out of head per degree of
crank rotation is not equal to the mass coming into the head from the cylinder. There will be a
pressure fluctuation in the head and this will affect the discharge of air from the cylinder. Driving
force for flow of air from the cylinder is proportional to (p – pd) in theoretical case and is
proportional to (p – ph) in actual case, where, p is the cylinder pressure, pd is the discharge
pressure and ph is the head pressure.
Suction Head: The air enters the cylinder during suction through the suction head. Driving
force for flow of air from the cylinder is proportional to (pa – p) in theoretical case and is
proportional to (ph – p) in actual case, where, p is the cylinder pressure, pa is the ambient air
pressure and ph is the head pressure.
Flow of air through the valve resists velocity changes because of its mass. The flow in
compressor manifold is intermittent. When a discharge valve opens, the gas flowing from the
cylinder has to push the gas already present in the manifold. This is a problem which increases
with the compressor speed. At 3600 rpm, the time available is only 1/60 s per revolution and only
a small fraction of this is available for the gas mass in the cylinder to be emptied into the manifold,
accelerating in turn the air already present in the manifold. The result is the development of a
back-pressure against which the compressor has to work and the losses can be significant. In
reality, pressure surge will be occurring in the manifold.
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Carl et al (1974) stated that the volume directly behind the discharge valve should be as
large as possible, as a minimum it should be equal to the cylinder volume for high speed
compressors, but preferably three times as large. The same is true for suction valves, since the
sudden filling of the cylinder depletes the supply of gas in the suction manifold and an under
pressure is created against which the valve has to work. The volume acts like a collection tank
or accumulator of gas, so that an over or under supply of gas can be stored temporarily.
2.5 Technical comparison (for the purpose of benchmarking and getting technical
know-how.)
Benchmarking and getting technical know-how is the tool to gather the input for designing
a product together with customer input capturing. Benchmarking is an important tool as it focuses
on the competitor USPs and attributes that act as a problem-solving tool and gives those
attributes for technical comparison of the product.
The process of Benchmarking depends for products to products and depends on the
product attributes. An engineer can define what can be extracted from the benchmarking of the
product. Although there is a standard process it cannot satisfy for every mechanical device, so
an engineer intervention is required to judge whether these parameters to be included or not for
the benchmarking.
For us, we defined the below process to benchmark competitor product. To achieve the
required input from the existing design and Technology. (See Appendix A)
2.5.1 Benchmarking process definition: -
2.5.1.1 Benchmarking Of
●
●
●
●
Make Name,
Product Name,
Part Number,
Mention Distinguished Feature,
2.5.1.2 Background
●
It defines the period of work or time taken to carry out this process. (this time is further
added to the development time of the product.),
Start Date
DD-MM-YYYY
End Date
DD-MM-YYYY
●
Mention why the project was taken up and what are the expected deliverables with
reference (e-mail or letter of reference or any specific customer request or
department request),
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2.5.1.3 Photograph of product
Description of product with important features of it.
Mostly this photograph should be of all the views top, bottom, sides and special fitments,
name plate and stickers.
2.5.1.4 Contents of Report
Mention in brief about what this report covers this may vary sometimes but it must contain
the following things: -
● Mounting details and sectional
drawing,
● Product application details,
● Performance parameters for
measurement,
● Performance test under
different condition,
● Product function and working
cycles,
● Cross-sectional details of the
product,
● Bill of Materials,
● Design calculation,
● Functional analysis,
● Diagnosis of design;
● Good features,
● Potential trouble,
● Possible improvements,
● Features, which can be
adapted from this design,
● Conclusion and Further
course of action,
2.5.1.5 Mounting details and sectional drawing
This may be available in catalogues or search on websites. Provide maximum technical
details available about the product including port details.
Following information to be covered
● Name plate details,
● Mounting port details with
thread size and depth,
● Mounting flange details- Hole
size/pitch/Contact area,
●
●
Weight,
Overall envelope dimensions
(Length X breadth X height)
2.5.1.6 Product function details: -
The function of the product in the brake system to be covered. This should also include
the technical parameter of the product before and after in the circuit. And how this function can
affect the other circuit parts.
2.5.1.7 Performance parameters: -
Performance parameters Specified in Product GA drawing to be covered.
Or can be taken from test results.
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2.5.1.8 Performance Test Details
Performance test details should include the below parameters: -
●
Test circuit
●
Evaluation Criteria
●
Testing conditions
●
Performance test graphs.
●
Test sample details
●
Test Result and conclusion
2.5.1.9 Product Function
Product Function includes the common function of the product and the additional feature
of the product. It should also include the detail of the vehicle output and product input, this helps
us to obtain the use of energy and system diagram.
2.5.1.10 Working Cycle
Working cycle includes the basic primary function circuit and a secondary circuit.
2.5.1.11 Bill of material
Bill of material is an important tool to determine the functionality of each part and its use
in the product.
a standard bill of material includes the below points.
●
Serial Number,
●
Quantity,
●
Part Name,
●
Material,
●
Part Number,
●
Surface Treatment,
●
Part Photograph,
●
Weight,
If there are more the one maker or more variants then detail of each is to be compared.
2.5.1.12 Design Calculation
Design calculation includes the below points.
● Product specific calculation,
● Design of springs,
● Equivalent flow area
calculation,
●
●
Performance prediction,
Standard feature,
2.5.1.13 Technical Comparison sheet
Functional Analysis includes below points: -
● Serial Number, ● Part Number and Name,
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●
Displacement,
●
Mounting,
●
Cooling (Air/Water),
●
Drive (Gear/Belt),
●
Operating Pressure,
●
Aftermarket/OEM,
●
Bore Diameter,
●
Special Feature or USP like.
●
Stroke,
ESS,
●
Max. Speed (R.P.M),
●
Through drive feature (yes/no)
●
Weight,
2.5.1.14 Diagnosis of design
design.
The diagnosis of the design gives the possible improvement to be taken from the existing
2.5.1.15 Features which can be adapted from the existing design.
It provides an idea for implementing some important parameters in existing models.
If there is some failure already in the benchmarking design, we consider those faults as
experiment result and come up with a new idea.
2.5.1.16 Conclusion
Conclusion for this benchmarking technique gives the relevant results for the designing
of this product.
See Appendix B for child part wise study.
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Below are the know-hows found from the study of 6 European and 6 Asian compressors: -
Table 2.1: Conclusion derived from technical comparison
S No.
Conclusions
1 All Compressors are lubricated through engine oil. This engine oil is provided from the tank
that provides engine oil to the engine. Except for LP1158 in, this compressor the oil is filled
in the crankcase with small time duration.
2 All these commercial vehicle compressors are single cylinder.
3 All these commercial vehicle compressors are single acting.
4 All these commercial vehicle compressors are single stage.
5 Some Compressors having flange mounting also has same base as the crankcase are
similar. So, it can be assembled on same fixtures of the assembly line.
6 Port orientation and port details are identical in casting parts, different machining or
converters/ adapters are used for the changing the port size.
7 Compressors having flange mounting with the engine are gear driven. Others which have
both oil inlet and outlet port are belt driven and can be base or chassis mounted.
8 Compressor which is involved in this study and is coolant cooled, receives coolant from the
same coolant tank, which that supply coolant to the engine.
9 Compressors having through drive feature drives addition pump by transferring the torque of
the crankshaft getting driven by the gear assembly or belt assembly.
10 Efficiency of these compressors are from the range of 45% to 55%.
Page 38 of 93

3 POSSIBLE APPLICATION OF COMPRESSOR IN VEHICLE
3.1 Introduction
Identifying the usage area of compressed air in a commercial vehicle:
●
●
●
●
Used to control vehicle using pneumatic braking system (Air Braking system),
Used in trailer controlling equipment (Trailer Control valves),
Suspension system,
Also used in alert system to inform driver about various systems on the truck,
As the designing of this compressor is for commercial vehicles introduction to the
commercial vehicle components where this compressed air from the compressor is required and
going to be used should be defined.
This study also provides us with the design inputs for this air compressor. As commercial
vehicles are large in size and heavy in weight, hence there is requirement of pneumatically
controlled devices to control the system of a commercial vehicle. System other than the
pneumatic controlled are not much capable to control such heavy load and size. There are some
alternates of the pneumatic controlled systems on a commercial vehicle but they will add a huge
cost to the overall price of the truck/bus. And also, can’t fully satisfy the requirement of the vehicle.
This type of system is not used in small vehicles as to manufacture pneumatic controlled system
for small vehicle is not cost effective and also it is huge in size for a small vehicle, it will add a lot
of weight.
3.2 Air Braking System
In the (Fig. 2.3) we can see the overall circuit of an air braking system. Each component
of an air braking system is dependent on the compressed air and hence dependent on the
compressor. All the problems with compressors can affect on the breaking failure of the vehicle
that is a huge safety factor. So, compressor is always ensured to build continuous pressure for
the air braking circuit. Below are some of the important components of an air braking system. [6]
3.2.1 Air Dryer
Air dryer is usually the first component after the compressor in the air braking circuit
system.
The basic function of air dryer:
●
●
●
To remove humidity from air, purify the air coming from the compressor, i.e
drying air.
To control air pressure in the tanks.
To provide signal to the compressor for start and stop of work.
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Air from the compressor is introduced into the air dryer inlet port and cooled through the
body wall surface to accumulate water and oil contents at the bottom of the body. The air further
passes through the filter with an oil mist separator equipped to remove micro oil droplets and dust
and then is introduced into the drying barrel, where water content remaining in the air is removed
with desiccant having strong affinity for water. As the air moves from the bottom to the top of the
drying barrel, it comes into contact with more dried desiccant, thus further reducing the water
content to turn the air into dry air at the top end of the drying barrel. The dry air is introduced into
the governor chamber and the main reservoir via the check valve and the purge chamber located
at the top of the drying barrel through the check valve mounted to the outlet port section.
Port definition of an Air dryer with respect to compressor.
Port 1- Inlet Port: - Inlet port (Fig. 3.1:1) of the air dryer is directly or in series connected
to the compressor the air dryer gets the air from this port further it filters the air and send further
for the air braking application.
Port 21- Delivery Port:- Delivery port (Fig. 3.1:21), After the filtration process the air is
then further sent for application purpose, this air from deliver port is collected in 3-4 tanks, this
delivery port is specially assembled with a single check valve (Fig. 3.1:c) the purpose of which is
to ensure that the pressure going in the forward direction should not return to the circuit and no
back pressure is created. Back pressure (if created) will harm the compressor function.
Port 22- Purge Port: - Purge Port (Fig. 3.1:22), is also connected with the compressed
air, purge port provides the back pressure to the desiccant (Fig. 3.1: a) to break the bed of dust
and dirt, collected over the desiccant on the desiccant case. If this purge pressure will not be
provided to the air dryer and the bed of dust and dirt will get collected on the desiccant, this will
block the compressed air to enter the air dryer and the flow rate of the air will be reduced hence
the performance of the air compressor will be affected.
Port 3- Exhaust Port: - Exhaust port (Fig. 3.1:3) is used to exhaust the excess air from
the compressor to the environment. To prevent excess pressure in tank and prevent bursting of
the tank. Exhaust port is also called as safety valve that is used to protect the Air braking system.
Usually, this valve opens at 14 to 15 bar of pressure.
Port 4- Control Port: - Control Port (Fig. 3.1:4), Is used to send signal to air compressor
for start and stop working. This feature is not available in all the air dryers as well as all air
compressor but the new generation air compressors are designed with this feature.
This control feature in the compressor provides signal based on this signal the
compressor outlet valve gets by-passed and the compressed air get directly into the air dryer
where it gets exhausted from the exhaust valve.
This reduces the load on the engine to drive the shaft of compressor. As the load on the
engine is reduced so it increases the fuel economy of the commercial vehicle. [6]
Page 40 of 93

Figure 3:1: Air Dryer (component of air braking system)
3.2.2 Multi Circuit Protection valve
Multi Circuit Protection Valve is the second in basic circuit of an air braking system. Basic
function of a multi circuit protection valve is to protect the compressed air from the compressor
to surge and to restrict pressure to bleed out from each of the outlet ports to backflow. Multi circuit
protection valve also restricts backflow.
Below is the port description for multi circuit protection valve.
Port 21- Primary outlet Port, this port is connected to the inlet of the primary air tank, and
this port transports the compressor air from the air compressor to it via filtration process from the
air dryer.
Port 22- secondary outlet Port, this port is connected to the inlet of the secondary air
tank, and this port transports the compressor air from the air compressor to it via filtration process
from the air dryer.
Port 23- Tertiary outlet Port, this port is connected to the inlet of the tertiary air tank, and
this port transports the compressor air from the air compressor to it via filtration process from the
air dryer.
Port 24- Quaternary outlet Port, this port is connected to the inlet of the Hand control
valve, and this port transports the compressor air from the air compressor to it via filtration
process from the air dryer.
Page 41 of 93

Figure 3:2: Multi Circuit Protection Valve (component of air braking system)
These ports allow only one-way flow. hence it protects from backflow and leakage of
pressure. It avoids pressure drop in the air brakes circuit. [6]
3.2.3 Air Tank (Reservoir)
A reservoir or an air tank is a cylinder where all the air produced by the compressor is
stored, to supply the air braking system with a continuous air and to maintain uniform flow rate
the pressure storage in the tank is required.
There are 3 to 4 tanks installed in a commercial vehicle for the purpose of regular supply
of compressed air and safety.
Figure 3:3: Air Tank (component of air braking system)
Usually, tanks have 3 to 4 ports. Details of the function is given below.
Port 1- Inlet Port: - Inlet port allows the air inside the tank.
Page 42 of 93

Port 21- First Delivery Port: - This port provides the compressed air which is stored in the
compressor to the dual brake valve upper portion for rear brakes.
Port 22- Second Delivery Port: - This port provides the compressed air which is stored in
the compressor to the dual brake valve lower portion for front brakes.
Port 23- Third Delivery Port: - This port is connected to the exhaust check valve, the
purpose of this valve is to remove the air from the tank for service purpose or cleaning purpose.
[6]
3.2.4 Dual Brake Valve
Figure 3:4: Dual Brake Valve (component of air braking system)
Dual Brake valve is also called as foot valve it is the valve which is pressed by the driver
of the vehicle to prove signal in case of braking this signal is generated with the compressed air
achieved from the compressor. Pressure is always maintained in this circuit, when the brake
pedal is pressed then there occurs pressure increase which opens the valve inside the foot brake
valve and the delivery port is then connect with the tank supplied the pressure, Dual brake valve
is an advanced technology from single brake valve, single brake valve was initially used in
braking system, the problem with the single brake valve was that, if it fails the whole system
baking system is failed. Later this problem was solved by introduction of one more valve level in
the dual brake valve, New generation dual brake valve has 2 supply and 2 delivery, from the 1st
supply and 1st delivery the rear brakes are governed, and from the 2nd supply and the 2 nd
delivery, the front brakes are governed. The 2 circuits have a time difference which provides more
stability to the vehicle. Port Definition for the dual brake valve.
Page 43 of 93

Port 11- Primary inlet Port: - Primary inlet port is the port from which the dual brake valve
receives the inlet of compressed air from the compressor, and use this air for the application of
the primary brake circuit.
Port 12- Secondary inlet Port: - Secondary inlet port is the port from which the dual brake
valve receives the inlet of compressed air from the compressor, and use this air for the application
of the secondary brake circuit.
Port 21- Primary delivery Port: - Primary delivery port is the port from which the dual
brake valve transfers the inlet of compressed air from the compressor, to primary brake circuit.
This port is in series connected to relay valve.
Port 22- Secondary delivery Port: - Secondary delivery port is the port from which the
dual brake valve transfers the inlet of compressed air from the compressor, to secondary brake
circuit. This port is in series connected to relay valve.
Port 3- Exhaust Port: - Exhaust port in the dual brake valve is used to exhaust the excess
air after the use in the circuit is over. [6]
3.2.5 Brake chamber and Spring Brake Actuator.
Figure 3:5: Brake chamber (component of air braking system)
All trucks, tractors, and buses using air pressure to apply the service brakes must be
equipped with emergency brakes and parking brakes. The parking brake must be held on by
mechanical force (because air pressure can eventually leak away). Spring brakes are usually
used to meet the emergency and parking brake requirements. When driving, powerful springs
are held back by air pressure. If the air pressure is removed, the springs put on the brakes. A
parking brake control in the cab allows the driver to let the air out of the spring brakes. This lets
the springs put on the brakes. A leak in the air brake system will generally cause the springs to
put on the brakes. Tractor and straight truck spring brakes will come fully on when air pressure
Page 44 of 93

drops to a range of 20 to 45 psi or 140 to 310 kPa (typically 20 to 30 psi or 140 to 210 kPa ). Do
not wait for the brakes to come on automatically. When the low air pressure warning light and
buzzer first come on, bring the vehicle to a safe stop right away while you can still control the
brakes. The braking power of spring brakes depends on the brakes being in adjustment. If the
brakes are not adjusted, neither the regular brakes nor the emergency/parking brakes will work
correctly. [6]
Figure 3:6: Spring Brake Actuator (component of air braking system)
3.3 Trailer control system
Trailer control system basically consists of the 4 components. This system uses the
compressed air from the compressor to perform its function.
3.3.1 Trailer air supply control
3.3.2 Trailer air tanks
3.3.3 Trailer control valve
3.3.1 Trailer air supply control
The trailer air supply control on newer vehicles is a red 8-sided knob which controls the
tractor protection valve. Pushing it in supplies the trailer with air, and pulling it out shuts the air
off and puts on the trailer emergency brakes. The valve will pop out and close the tractor
protection
Page 45 of 93

Valve when the air pressure drops into the range 20 to 45 psi. Emergency valves on older
vehicles may not operate automatically. There may be a lever rather than a knob. The normal
position is used for pulling a trailer. The emergency position is used to shut the air off and put on
the trailer emergency brakes. [6]
3.3.2 Trailer air tanks
Every combination vehicle has two air lines—the service line and the emergency line.
They run between each vehicle (tractor to trailer, trailer to trolley, trolley to second trailer, etc.).
Trailer air tanks:
Each trailer and converter dolly has one or more air tanks. They are filled by the
emergency supply line from the tractor and they provide the air pressure used to operate trailer
brakes. Air pressure is sent from the air tanks to the brakes by relay valves. The pressure in the
service line tells how much pressure the relay valves should send to the trailer brakes. The
pressure in the service line is controlled by the brake pedal and the trailer hand brake. It is
important that water and oil are not allowed to build up in the air tanks. If they do, the brakes may
not work. Each tank has a drain valve on it and must be drained every day. If the tanks have
automatic drains, they will keep most moisture out. However, the drains should still be opened
manually to check for moisture.
3.3.3 Trailer control valve
Trailer control valve is a device that is used in commercial vehicle for the control of load
and the unloading of the trailer that is attached to the tractor. Basically, the Trailer control valve
has
Port 1 : Inlet connect to the supply from the compressor,
Port 2 : Outlet port connected to the actuator of the trailer.
Port 3 : Exhaust port to exhaust the excess air out of the trailer control valve.
Port 41,42,43: Control port for controlling the features of the trailer.
Page 46 of 93

Figure 3:7: Trailer control valve
3.4 Suspension system
Figure 3:8: Suspension system
Suspension system of the commercial vehicle braking system also includes the
intervention of the compressed air and hence the compressor. The compressed air is supplied to
the suspension chamber from the auxiliary port of the protection valve to provide a flow of single
direction and when there is any leak observed from the suspension system protection valve stops
the supply of the compressed air to the suspension system. But as compared to air braking
system these auxiliary feature use less compressed air.
Page 47 of 93

3.5 Emergency alert system
Figure 3:9: Pressure Gauge
An Emergency feature was an early addition to Westinghouse's technology. This added
a second reservoir and made the control valve more complicated, but it also allowed for a harder
application of the brakes. And, with a propagation feature called "Quick Action", it made them
apply very quickly too. ‘Emergency’ adds a fourth mode to the brake system.
A rapid decrease in brake pressure signals the valve to immediately start stopping the
train. Including the full contents of a second, larger reservoir, called the ‘Emergency’ reservoir.
(The original reservoir is now called the ‘Auxiliary’ reservoir. Most freight cars use a duplex
reservoir, which are two cast halves separated by a steel plate. The steel plate is shaped like a
dome inside, which makes the emergency half of the reservoir larger. A tab sticks out of this steel
plate, one side labelled "aux" and the other "emergency" so the sides can be identified.
In normal operation, the emergency-equipped control valve operates just like the original
triple valve, except, of course, that it also charges the emergency reservoir. But part of the valve
is designed to detect a rapid drop in pressure, which trips the emergency mode. The valve will
then dump the entire contents of both reservoirs into the cylinder, and when pressure equalizes,
there will be nearly full system pressure in the cylinder, 63 pounds or so on a 70-pound brake
pipe pressure. This is as hard as the brakes will go, and will often lock up the axles at low speeds,
skidding flats in the wheels. The force of an emergency application can also damage lading or
even derail the train! An emergency stop is now the default action almost anytime there's a brake
failure. Any rupture in the brake pipe will cause an emergency application, as will a defective
brake valve pejoratively called a ‘kicker’ or ‘dynamiter’ (which puts the whole train in an
emergency.) [6]
Page 48 of 93

Figure 3:10: Hand controlled Brake valve
3.6 Tyre Inflator
As the commercial vehicle is very heavy in size and usually travel to the roads less taken,
there are chances of failure of the truck tyres, in this situation the truck will be stuck if there will
be no shop to repair the tyres nearby, to cure this situation the commercial vehicle is fixed with
an additional and optional valve known as Tyre Inflator valve this device use the pressure from
the compressor and refill the pressure in the tyre.
Additionally, now in many trucks and other vehicles, there is a feature of automatic tyre
pressure maintenance, this feature also maintains proper tyre pressure using the air pressure
from the compressor.
In the figure 3K, we can see the feature of tyre inflator is assembled to the valve. some
Tyre inflators are also manual. [6]
Page 49 of 93

Figure 3:11: Tyre Inflator
3.7 Through Drive
Through Drive is a feature to transfer the torque of engine to drive other components
installed on the commercial vehicle. Through Drive feature is machined on the shaft to supply a
through connection from compressor. One of the through drive use is fuel pump. The fuel pumps
were initially driven by separate motor or drive, but the help of this feature through the compressor
it was made possible to save cost, space, weight, and also efficiency of the vehicle.
A fuel pump which is not delivering the proper amount of fuel will limit performance and
result in a lean fuel mixture. This will cause the engine to run hotter than normal and, as
consequence, lead to burned valves. If the pump is delivering too much fuel, both performance
and fuel mileage will be compromised. Fortunately, fuel pump problems are easily fixed. [6]
Figure 3:12: Shaft with Through Drive Feature
Page 50 of 93

4 SELECTION OF THE RELEVANT COMPRESSOR APPLICATION AND
DEVELOPMENT OF STRATEGY OF PROBLEM SOLVING.
As in the previous chapter we have seen the tools and techniques for the design input
capturing and the possible application of the compressor in the commercial vehicle. Selection of
relevant compressor application was obtained by evaluating the conclusion of the comparison
study and the customer input capturing. We concluded to design the compressor for main
application of air braking system and the through drive feature. Selection included the major
popular features in demand.
4.1 Application of compressor for air braking system
Designing the compressor applicable for the air braking system we need knowledge of
air braking components, circuit of the braking system, input and requirements of the air braking
system. The study of air braking system circuit and components is covered in the 2 nd chapter.
Now, we need the input attributes for the air braking system, this input should be output of our
compressor for the proper functioning of the air braking system.
4.1.1 Design Input capturing of Air Braking System
To check the input for the air braking system we know from chapter 2 that the air dryer is
the first component after air compressor to receive the compressed air, hence the requirement of
the air dryer should be the output of the compressor together with the attributes required by the
other components in the series. After summing up below is the requirement for the air braking
system.
• Generation of air with a flow of approx. 200 to 220 Litre/min. If possible, even
higher,
• Compressor should be capable to generate air pressure of up to 8 to 10 bar,
• Output temperature should not exceed 200°C to 220°C,
• Oil Carryover from the piston and the cylinder should not be more,
• Efficiency of the compressor should not be less than 60%.
• lifetime should not be less the life of Air braking system. (i.e. 1 million cycles)
4.2 Application of compressor for Through drive Input capturing
As the compressor is connected with the engine of the commercial vehicle and get the
drive force for its crankshaft either through a gear connection between the engine and the
compressor or by the help of a belt driving the shaft of engine connect to any motor or engine.
This torque can be transmitted to drive other devices that can come into function using this
mechanical power from the compressor shaft. To achieve this there are certain requirements and
design modification that acts as constrain. We can capture this input for the through drive.
Page 51 of 93

4.2.1 Design Input capturing of Through Drive System
Basically, this input is given by the customer as this feature is customer specific and in
general not many customers use this feature, but for the designing of our compressor, this feature
is required by the market. Below is the general requirement related to the through drive feature.
• The minimum torque requirement from the compressor to drive the feature of
through drive is approx. 30 Nm. (in case the customer is using this through drive
feature for driving a fuel pump.
• Secondly, the fitment details of the fuel pump are required.
4.3 Problem Solving Strategy
4.3.1 Problem and failures description
To solve the problems for the commercial vehicle compressors we need to capture the
major failures and problems that can occur and should also study the effect of the problem that
are observed. From benchmarking tool and field visit, we have captured the below problem that
are generally observed in the commercial vehicle compressors.
Field issues observed
4.3.1.1 Air pressure not getting developed.
Air pressure not developed is the major and basic functional failure observed in this
product. The risk rate for this failure is very high. Due to his failure the complete braking system
will fail. Hence to solving this problem will lead to the betterment of the product function. For
safety reasons to counter cure this problem function of emergency valve is designed in a counter
way than other braking system components. If the compressor does not build pressure and also
the pressure stored in the tanks get used in that case the emergency valves get activated. The
emergency valve activation will stop the vehicle by applying the emergency brakes. this is done
to avoid accidents.
Suspected reasons for this problem are: -
• No Driver
• Leak in delivery
• Gasket Fail
• Blockage in inlet
• No proper rpm
4.3.1.2 Pump Time Increased
Time required to fill the tank for the use of the air braking system gets increased.
Suspected reasons for this problem are: -
• Blockage in inlet
• Leak in delivery
• Reed Valve Failure
Page 52 of 93

4.3.1.3 Oil Carry Over
Oil Carryover is the second major problem observed in a compressor; the oil carried with
the flowing air developed by the compressor harms the other components of air braking system
present in the circuit.
Suspected reasons for this problem are: -
●
Back Pressure in Crankcase
●
Blockage in inlet
●
Cylinder bore or Piston Ring
damage
4.3.1.4 Noise
Suspected reasons for this problem are: -
● Size of compressor ● Weight of the compressor
As we captured the problem observed from the field report, it was analysed for the root
cause analysis, parameters and attributes involved in the problem was then examined for the
relevant solution. After evaluating the parameters and attributes many design features was
established to obtain the required result of the compressor. Implementing proper design feature
considering mathematical modelling and validation strategy of the product and DFMEA helped in
selecting of proper problem-solving strategy making.
Table 4.1: Design Features used for problem-solving
S No. Design Features Design Features used to solve the field issues
1 Light Weight 1) Using Iron Liner(Fe)
2) Using glide bearing and not ball bearing
Approx. 25% less weight then competitor.
2 High Efficiency 1) Smaller clearance between piston and head
2) Better Heat Transfer
3) Lower power consumption
4) Higher air flow/ higher delivery rate
3 Low oil carry over 1) Smaller con. rod angle design
2) Using Aluminium Crankcase(AL) with Iron Liner(Fe)
3) Better Heat Transfer
4 Better Heat Transfer 1) Bigger cooling room
2) Better cooling setups
5 Energy saving system 1) Less Power consumption
2) Better fuel economy
Page 53 of 93

5 DEVELOPMENT OF THE ALGORITHM FOR CALCULATION OF A
COMPRESSOR
5.1 Mathematical modelling of compressor
Mathematical modelling is the process of designing a model of a real system and
conducting experiments with it for the purpose of understanding the behaviour of the system.
Mathematical simulation is widely used for investigating and designing the compressors.
Investigation of the processes of reciprocating compressors using mathematical models is an
effective tool by high development of computing technique, which enables complicated problems
to be solved with a minimal number of simplifying assumptions. A considerable number of
previous works has been done on the mathematical modelling and simulation. This thesis
presents a simplified and effective mathematical model for the estimation of reciprocating
compressor performance using personal computers that can be easily handled.
The developed model has been validated using the experimental results from the
compressor with reed valve in the delivery side and ring valve in the suction side. The compressor
is tested for different delivery pressures and different shaft speeds. The effect of parameters
speed, discharge pressure on thermodynamic behaviour of compressor in working condition has
been analysed. The model can predict cylinder pressure, cylinder volume, cylinder temperature,
valve lift and resultant torque at different crank angles and free air delivered and indicated power
of the compressor. The predicted results using the developed mathematical model are very much
comparable with the experimental results. [1]
Table 5.1 Bore and stroke comparison for relevant selection
Stroke in mm
Stroke volume in cm3
38 40 44 46 50 54 56
65 126 133 146 153 166 179 186
70 146 154 169 177 192 208 215
75 168 177 194 203 221 238 247
Bore Dia.
mm
78 181 191 210 220 239 258 267
80 191 201 221 231 251 271 281
86 221 232 255 267 290 314 325
90 242 254 280 292 318 343 356
92 252 266 292 306 332 359 372
100 298 314 345 361 393 424 440
Page 54 of 93

As our target was to design compressor that can replace competitor 230cc compressor
with certain USP. We did certain trials to select relevant bore and stroke for modelling our design.
Calculation of the compressor standard parameter was done for most of the values for the bore
and stroke given in Table 5.1. finally, the relevant bore value and stroke value was selected. Bore
and stroke values are required for overall packaging study of the compressor, it affects the length,
width and height of the product this dimension are important for the fitment details of the designed
compressor in the truck/bus at customer end.
5.1.1 Bore (d):- It is the inner diameter of the cylinder where the piston moves.
Bore provides the outer diameter of piston and inner diameter of the cylinder. Bore is
usually considered as a standard dimension. Based on this standard dimension of bore (d) and
stroke(S) the displacement is decided. Tolerances are provided to cylinder inner diameter and
piston outer dimension for free movement of piston inside the cylinder.
For our case, we are considering bore of Ø80mm. And provided the tolerance of
clearance fit for free running.
• Cylinder Inner Diameter Ø80 H9 +0.07
-0.10 to -0.17
• Piston Outer Diameter Ø80 d9
Figure 5:1: Bore
5.1.2 Stroke (S):-
It is the distance between the top dead centre (TDC) and bottom dead centre (BDC).
It provides the height required for piston movement.
S =
V × 4
Π × d 2 × N × λ (mm)
S =
471 × 4 × 1000000
3.14 × 80 2 = 46 mm
× 3000 × 0.68
Page 55 of 93

Figure 5:2: Stroke
5.1.3 Displacement (D):-
D = Π × S × d2
4
D = Π × 46 × 80x80 = 231 cc
4
Figure 5:3: Displacement (Sweep Volume)
5.1.4 Air Flow (V): -
V = V R × P 2 × 60
t p
V =
50 × 8 × 60
51
= 471 lpm
5.1.5 Volumetric Efficiency (λ):-
λ =
V × 4
Π × d 2 × N × S
Page 56 of 93

λ =
471 × 4 × 1000000
3.14 × 80 2 × 100 = 67.88 %
× 3000 × 46
5.1.6 Clearance Volume (V c): -
volume
Clearance volume is generally considered to be less than 5% for better efficiency.
V c = D × 3%
V c = 231 × 0.03 = 6.93 cc
By calculating the height of the cylinder for this volume we get the size of the clearance
h cv =
V c = Π × r × r × h
6.93
= 1.3 mm
3.14 × 40 × 40
this dimension is added to the height of the cylinder.
Figure 5:4: Clearance Volume
5.1.7 Stroke to bore ratio: -
The stroke ratio bore is considered good in the range 0.6:1
S: d = Stroke
Bore : Bore
Bore = 0.58: 1
5.1.8 Air intake per min(V 1):-
V 1 = D × N
V 1 = (231 / 1000000) × 3000
Page 57 of 93

V 1 = 0.69 m 3
5.1.9 Mass flow rate (m): -
m = P 1 × V 1
R 1 × T 1
conversions: -
0.97 bar intake pressure to 97200 Pascal
35°C Room temperature to 308.15 Kelvin
m =
97200 × 0.69
287 × 308.15
m = 0.761 kg/min or 0.012 kg/ sec
5.1.10 Crank Radius (r): -
r =
Stroke (S)
2
r = 46
2
r = 23 mm
Page 58 of 93

Figure 5:5: Stroke and crank radius
5.1.11 Outlet Temperature (T 2): -
T 2 = T 1 (p 2 /p 1 ) n-1/n
T 2 = 308.15(8/0.97) 1.35-1/1.35
T 2 = 532.22 K
5.1.12 Indicated power (Pi): -
Pi =
Pi =
n
n − 1 × m × R 1 × ( T 2 − T 1 )
1000
1.35 0.01269 × 287 × ( 532.22 − 308.15 )
×
1.35 − 1 1000
Pi = 3.15 Kw
5.1.13 Belly inner dia. (Ø bi ): -
Ø bi = 2 × ( r + connecting rod thickness + clearance for Heat Transfer )
Ø bi = 2 × (23 + 3 + 5)
Ø bi = 62mm
Page 59 of 93

5.1.14 Belly outer dia. (Ø bo ): -
Ø bo = Ø bi + minimum thickness
Ø bo = 62 + 5 = 67mm
5.1.15 Connecting rod length (l): - the connecting rod angle of less the 16° is considered good.
l = r / (TAN Ө)
l = 23/ (TAN 16°)
l = 80mm
Figure 5:6: Crank angle and length
5.1.16 Connecting rod angle (Ө):-
For reverse calculation or for benchmarking of other samples we need the below formula
to know the competitors connecting rod angle.
Ө = 180
3.14 × (TAN −1 ( r l ))
Page 60 of 93

Ө = 180
3.14 × (TAN −1 ( 23
80 ))
Ө = 16°
5.2 Stack-up calculation
Table 5.2: Stack up calculation for crankcase centre to cylinder
Description
Dimension
mm
Positive
Tolerance
As per ISO 2768 mk
Negative
Tolerance Maximum Minimum
Crankcase centre to cylinder top
face A
Hb 130 0,5 0,5 130,5 129,5
Crank Radius r 23 0,05 0,05 23,05 22,95
Piston Crown Height Hpc 25 0,05 0,05 25,05 24,95
Connecting B Rod Length l 80 0,05 0,05 80,05 79,95
Total Dimension B Hb' 128 128,15 127,85
Height C (Clearance Volume)
hvc
Dim. A-
Dim. B 2,35 1,65
Mean of Height (clearance
Volume) ≈ (2,35+1,65)/2 = 2
Page 61 of 93

Figure 5:7:Stack-up diagram
5.3 CAD/CAM & Material selection: -
Based on these formulas (mathematical modelling) below parts were designed in
SolidWorks and then later relevant parts were imported to Ansys for the FEA/CAE analysis.
Based on the type of material we divided the parts into two commodities.
Page 62 of 93

Figure 5:8: Exploded view
Page 63 of 93

5.3.1 Designing and material selection of aluminium parts (commodity 1)
We are taking here an example of connecting rod used in compressor to explain the
designing and material selection process, based on this method all the parts belonging to this
commodity was designed.
Solidworks mechanical design automation software is a feature-based, parametric solid
modelling design tool which advantage of the easy to learn windows graphical user interface. We
can create fully associative 3D solid models with or without while utilizing automatic or relations
to capture design intent. Parameters refer to constraints whose values determine the shape or
geometry of the model or assembly. Parameters can be either numeric parameters, such as line
lengths or circle diameters, or geometric parameters, such as tangent, parallel, concentric,
horizontal or vertical, etc. Numeric parameters can be associated with each other through the
use of relations, which allow them to capture design intent. A Solidworks model consists of parts,
assemblies, and drawings. Typically, we begin with a sketch, create a base feature, and then add
more features to the model. (One can also begin with an imported surface or solid geometry). We
are free to refine our design by adding, changing, or reordering features. [8]
5.3.1.1 Designing the Connecting Rod (Using Solidworks) [8]
Table 5.3: Step in Solidworks for designing of connecting rod: -
Example
Steps
Connecting rod 2D
sketch and extrude
Material removal by
extruding extra
material maintaining
minimum thickness
Page 64 of 93

Example
Steps
Extrude for making
holes
Sketch extrude to
maintain the dia.
same as crankshaft
Material removal for
restricting Poka-yoke
Providing Radius
and chamfers for
surface smoothening
and removing sharp
edge
Page 65 of 93

After completing the modelling below steps are needed to perform an analysis depend
on the study and function of the product: -
• Create a study defining its analysis type and options,
• Define parameters of your study. (model dimension, material property, force
value, or any other input.),
• Define material properties.,
• Specify restraints and loads.,
• Define the meshing, in some cases the program automatically creates a mixed
mesh when different geometries (solid, shell, structural members etc.) exist in
the model. Mesh the model to divide the model into many small pieces called
elements. Fatigue and optimization studies use the meshes in referenced
studies,
• Define component contact and contact sets,
• Run the study,
• Evaluate the results,
5.3.1.2 Analysing the connecting rod (using Ansys 14.5 workbench software (student version))
We compared the result of 2 to 3 types of materials for each designed part for suitable
materials. Table 5.3 shows the material used in analysis of connecting rod.
Table 5.4: Suitable materials for connecting rod
Material
Density
Young's
Modulus
Poisson ratio
Shear Modulus
Kg/m3 pa pa
Aluminium alloy 2770 7.00E+10 0.33 2.66E+10
Titanium alloy 4620 9.60E+10 0.36 3.53E+10
42CrMo4 7830 2.10E+11 0.3 8.07E+10
Page 66 of 93

Table 5.5 : Ansys simulation for connecting rod
Analysing the connecting rod
Connecting rod model IGES file imported to Ansys
Load and fixed support
Meshing
Mesh Type:
Tetrahedral
No. of nodes: 16190
No. of elements:
8821
Page 67 of 93

Analysing the connecting rod
Structural Analysis: Material 1; Aluminium Alloy
Maximum stress
Total Deformation
Maximum Strain
Page 68 of 93

Analysing the connecting rod
Structural Analysis: Material 2; Titanium Alloy
Maximum stress
Total Deformation
Maximum Strain
Page 69 of 93

Analysing the connecting rod
Structural Analysis: Material 3; 42CrMo4
Maximum stress
Total Deformation
Maximum Strain
Page 70 of 93

Analysing the connecting rod
Modal Analysis result: - Material 1; Aluminium Alloy
Mode 1
Mode 2
Mode 3
Page 71 of 93

Analysing the connecting rod
Modal Analysis result: - Material 2; Titanium Alloy
Mode 1
Mode 2
Mode 3
Page 72 of 93

Analysing the connecting rod
Modal Analysis result:- Material 3; 42crMo4
Mode 1
Mode 2
Mode 3
Page 73 of 93

Table 5.6: Result: Structural Analysis
Material
Von mises Stress Total Deformation Max. Strain
(N/mm2)
mm
Aluminium alloy 2770 7.00E+10 0.33
Titanium alloy 4620 9.60E+10 0.36
42CrMo4 7830 2.10E+11 0.30
Table 5.7: Result: Model Analysis
Model 1 Model 2 Model 3
Material
Deformation Frequency Deformation Frequency Deformation Frequency
(mm) (Hz) (mm) (Hz) (mm) (Hz)
Aluminium
alloy 226.8 437.06 233.17 1560.7 236.88 2369.2
Titanium
alloy
42CrMo4
175.71 394.4 180.44 1404.1 183.57 2137.6
134.83 446.17 138.77 15597.8 140.79 2419
Conclusion
For comparisons of the results obtained from the static analysis result tables it is
concluded that 42CrMo4 show least stress and least deformation & strain value on same static
load condition. From the Modal analysis result tables, it is concluded that 42CrMo4 shows less
deformation results for given frequency. Hence for both Structural and Modal Analysis 42CrMo4
(Special Alloy Steel) it is best suitable material for connecting rod. [8]
Page 74 of 93

5.3.2 Designing and material selection for sealants (commodity 2)
There are more than 5 gaskets types available in a compressor, these are directly related
to the function of the compressor. Below is the list of some of the compressor gaskets and overall
function of these gaskets.
5.3.2.1 Function of sealants- It is defined as per their type of sealants
Types of Gaskets: -
●
Inlet Gasket,
●
End cover Gasket,
●
Delivery gasket,
●
Gasket for bottom plate,
●
Gasket between Cylinder head and
●
O-Ring,
Valve plate,
Functions of these gaskets: -
●
Provides sealing of air pressure,
●
Mounting of inlet and outlet reed
●
Controlling of clearance volume,
valve,
●
Control movement of inlet valve
●
Integrated with inlet reed Valve,
(valve lift),
●
Controlling axial play,
●
Control movement of outlet reed
valve,
5.3.2.2 Input Parameters
Profile of mating part.
Figure 5:9:input for gasket
Page 75 of 93

Possible applications or other features required with gasket.
●
●
●
●
Controlling of clearance volume.
Control movement of inlet valve (valve lift)
Mounting of inlet reed valve
Integration of inlet valve
Operating temperature range and working pressure
Environmental condition.
Applicable fluid- (Oil, Water, Air)
5.3.2.3 Output Parameter
Gasket shape & dimension.
Figure 5:10: Gasket shape
Thickness of gasket and coating.
Material of gasket and coating.
Table 5.8: Material selection for gaskets
Material
(coating)
Temperature
Range
Suitable with
Application
Asbestos Fibre
(No)
-40°C
+400°C
to
Oil, Air and Water
High Strength
Treated Paper
(No)
-40°C
+350°C
to
Oil, Air and Water
Low Strength,
High Compressibility
Aluminium Gasket
(silicon coated)
-40°C
+400°C
to
Oil, Air and Water
High Strength
Rubber NBR
(No)
-40°C to +80°C Oil Low Strength,
High Compressibility
Page 76 of 93

5.3.2.4 Rules for designing
Recommended specific sealing pressure for pressure tightness: 14 N/mm 2 .
Specific sealing pressure can be estimated by following methods:
Analytical method:
This gives approximate sealing pressure based on the assumption that the mating
components are infinitely rigid.
Stress analysis:
This gives the accurate sealing pressure distribution on the surface considering the
stiffness of mating parts.
Example for specific sealing load calculation -
Analytical method
Clamping load calculation / bolt
Pi = T/(K D)
Sealing will be effective in the shortest distance between two fastening points. Hence
gasket-sealing area should not be far away from the line connecting two adjacent
fastening points.
Figure 5:11: Torque line for gaskets
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Low volume of silicone results in less torque relaxation of clamping bolts.
Figure 5:12: Silicone on gaskets
Minimum / maximum width of gasket
●
●
Minimum width of sealant application : 3mm
Maximum width of sealant application : 5mm
Figure 5:13: Thickness for gaskets
5.4 losses in a commercial vehicle compressor
In reciprocating piston engines irreversible counterbalancing and friction processes are
superimposed on the desired reversible state changes, which in work machines leads to an
increased workload, in the case of combustion engines to a reduced work output, d. H. in any
case lead to losses. According to their cause, the losses are divided into leakage losses, throttle
losses and wall losses.
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Leakage losses occur as a result of leakage due to unavoidable leaks in the working
area. External leaks are easier to notice and limit than internal leaks. Increased internal leaks
can be recognized by their detrimental influence on machine performance. The degree of
machine sealing depends on the design and the operating conditions. Smaller degrees of
tightness are to be expected above all when using dry-running piston rings for high pressure
differences. A pre-calculation of the leakage losses is associated with great uncertainties, since
the gap surfaces occurring in the operating state are often dependent on wear and can only be
estimated with difficulty.
The total loss of pressure occurring in the control elements during the charge change
due to flow deflection also negatively influences the intake and output and is referred to as throttle
loss. The total pressure difference across the control members is approximately proportional to
the square of the piston speed. The throttling losses have a particularly strong effect on highspeed
machines with a low-pressure ratio. Their prediction is approximately possible.
Temperature differences between the working substance and the cylinder wall occur
during the work cycle, leading to a heat transfer with changing direction. They also have a
detrimental effect on the machine performance and lead to the so-called wall losses. Aiming at
reducing wall losses through relatively small working space surfaces and high speeds is only
sensible if an adiabatic state progression in the machine is desired.
Page 79 of 93

6 ANALYSIS OF THE RESULTS AND VERIFICATION
6.1 Introduction
To Analysis and verify the designed compressor we defined three steps. Including the
standard norms for testing commercial vehicle components.
●
●
●
Checking of fitment parts for no interference, (Before Prototype)
Checking of minimum thickness of material, (Before Prototype)
Perform validation tests to ensure the functionality, (After Prototype)
If was often observed during our designing that piston either strikes the crankcase,
Cylinder head, or most often the shaft. This can be ensured by calculating the stock of material,
and removing the extra material that can cause the stuck closing of the parts and constrain its
rotation. While performing this step we also need to ensure that removal of material should not
result in scarcity of material, If the minimum material available at a face is very less then it will
affect in braking due to application of pressure on the walls of compressor. We used solid work
tool to ensure the minimum thickness and stack up calculation (chapter 5.2) for ensuring that the
designed parts should not strike but also minimum gap to be maintained for the movement of
parts.
Verification of the design after the development of prototype model is also most
important, this can be done by comparing the required results of the model by the commercial
vehicle standard results. There are certain tests that are performed to ensure the proper
functioning of the model. So, we have described some of the test which can be performed to
ensure the functionality and validate the design.
6.2 Design Validation
6.2.1 Functional test or performance test-
This test is performed with the compressor to check general functionality of compressor.
By performing this test we can ensure the below points:-
• Movement of piston in the cylinder,
• Movement of the connecting rod without striking in the crankcase,
• Movement of the piston without string the reed valve or reed valve plate,
• Movement of the piston without striking the crankshaft,
• Building high pressure with a better flow rate,
• Flow of oil from the oil path provided in the compressor circuit,
• Functioning of the bearing provided for the rotational movements,
• Heat produced from the compressor,
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To ensure this test a circuit for the test need to be prepared, in which the shaft of the
compressor need to be connect for providing torque to it similar to the torque provided by the
engine of the vehicle and then below conditions need to be satisfied for conducting the test.
• Pressure of oil inside the compressor to be ensured: for approx. 2 to 4 bar,
• As the coolant in the compressor comes from the same source i.e. engine, and
due to the high temperature near the engine the coolant in the radiator of the
vehicle also gets a little hot, hence to ensure the environmental condition for the
testing, the temperature of the coolant is kept to be 100 °C,
• Similar to the coolant the temperature to the oil that enters the compressor is
also ensure to have a temperature of about 100° C,
• As discussed in (Chapter 4) the pressure requirement for the functionality of the
air braking system is about 6 to 10 bar so based on the model of air braking
system we can assume the required outlet pressure from 6 to 10 bar,
• Pressure of coolant inside the cooling circuit should move slowly for the proper
heat flow from inside to outside the compressor. So, the flow pressure of the
coolant is kept very low say 1 bar,
• To rotate the shaft, we need an external motor, in vehicle condition the torque
for the rotation of shaft is provided by the engine or an electric motor. the rotation
speed of the external motor to test the compressor should be ensured with the
speed of 2000 to 3000 rotation per minute
By applying these conditions below parameter can be observed for the performance
measurement of the compressor: -
1. Volume oil flow: [l/min]
2. Temperature air outlet: [°C]
3. Pressure air inlet: [bar]
4. Temperature air inlet: [°C]
5. Pressure ambient: [bar]
6. Temperature ambient: [°C]
7. Volume air flow: [l/min]
8. Drive torque: [Nm]
9. Volume coolant flow: [l/min]
10. Temperature coolant outlet: [°C]
These output parameters are then compared with the standard values for verification.
6.2.2 Pressure leak test
The pressure leak affects the performance of the compressor, the compressor may be
performing the required work but the outcome airflow may not be as per required, air leakage can
be one of the reasons for this kind of problem.
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Root cause of the air leakage from compressor.
• Crack in the external packing parts such as crankcase, cylinder and cylinder
head. This is usually observed because of the non-maintenance of the minimum
thickness on body of these parts.
• Blow holes in the casting of parts are also reason for the leak from the body of
parts. This kind of leak can be ensured by completely filling the inside on the
body with air pressure of 10 bar and closing all the outlets and then dipping this
assembly in water to observe the air coming out of it.
• Pressure leak due to leak in the fitted pipes connecting compressor with other
parts.
• Pressure leak due to improper sealing provided or improper torque provided to
the mating parts of the compressor.
Compressor is tested under these conditions for ensuring no leak and no performance
drop. If these leaks are observed there is a requirement of re-design or correction.
Figure 6:1
Figure 6:2: Test Circuit for leak and performance testing
6.2.3 Endurance Test
This test aims with the product durability and reliability under given controlled condition.
This test also show result which are observed after certain hours of continuous running of the
product. Endurance test or durability test is done to achieve the below mentioned points.
• Check the performance degradation after a span of time,
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• Leak from the components after continuous performing for a span of time,
• Wearing out of parts after a span of time,
• Oil carry over from the crankcase after a span of time,
• Increase in power consumption after a span of time.
• Failure of a child part of the compressor.
• Complete failure of the compressor.
• This test also provides the data for preparation of repair kit,
• Life time of the compressor,
Performing this test gives a lot of strength in form of failures to verify and correct the
component, the acceptance criteria for this test is- no major failure of parts and change in
performance also less or within the defined specification
6.3 Tightening torque verification
To ensure the correct tightening torque for a component, we can assemble the mating
parts where external torque is proved to the bolts and nut to ensure the holding of the parts
together, with sealing parts overlapped with Fujifilm (sealing side) as per the specified torque,
and observe the impression on Fuji film to ensure proper sealing.
Figure 6:3: Fujifilm impression
**Acceptance Criteria- No week impression.
Page 83 of 93

7 CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE
APPLICATIONS
7.1 Conclusion
Target for us was to develop a concept of compressor for commercial vehicle, which
included certain guidelines from the market and customer input. We selected a defined path to
develop this concept based on the scope of work. Each level of this path was conclusive and is
described below.
• Brief study about the available theoretical knowledge and experiments already
conducted by professionals was performed during this project.
• Brief study about commercial vehicle compressor and it’s working, functionality
and performance was done in this project. Also comparison of 6 European and
6 Asian compressor on the basis of various parameters such as difference
between child parts performance, input and output attributes was done. Doing
this we performed the literature survey on existing design.
• Brief study of the possible application such as air braking system, trailer control
system, tyre inflator, through drive system etc. was performed in depth to
understand which compressor parameter can affect the functionality and
performance of the other related component.
• Performing the application study and comparing it to the market requirement
leaded us to the selection of the relevant compressor application and strategy of
problem solving including less oil carry over, high air flow and delivery pressure,
better heat transfer, less power consumption, lightweight and a better life time.
• Mathematical Modelling and calculation of performance parameter based 3D
modelling on solidworks 2016 was done, considering the stock of material
calculation and material selection. Later this 3D was imported to Ansys in IGES
format to perform FEA, CFD calculation, heat transfer & fluid flow. This level lead
us for development of the concept of compressor for commercial vehicles.
• Study of the validation testing including vibration testing, noise testing,
performance testing, leak testing & durability testing was done to ensure the
proper functionality to ensure the error free concept.
7.2 Recommendation for future
Literature survey on compressors lead us to the first man made compressor back in 1500
BC shown below. Since then to the present date the continuous modernization and technical
advancement have taken over and resulted in the compressors, we see today around us.
Use of Air braking system using compressed air dates back to 1850’s and first
commercial use started from screw compressors in 1872 in commercial railways.
Page 84 of 93

Table 7.1: History for application of compressors in vehicle
RAILWAYS - 1872 TINCHER CAR - 1903 WWII TRUCKS - 1949 HCV - 2019
Over 150 years the technology developed and applications increased to Heavy
commercial road vehicle for many applications and current technology uses reciprocating
compressors.
The properties and attributes of this concept of compressor ensures the
recommendations to be used in heavy commercial vehicle which has the below requirements
from the compressor: -
• Higher performance and air flow value,
• Light in weight to reduce the overall weight of the vehicle,
• Less power consumption,
• Use of advanced material to reduce heat generated during reciprocation in the
cylinder and piston unit.
• Less oil carry over to ensure good air quality, it reduces the serviceability of the
compressor and the other components of the commercial vehicle air braking
system.
• To ensure the higher braking power due to increasing demand of the braking
power for heavy load vehicle.
• This study can be continued for the development of advanced oil free
compressor.
Page 85 of 93

8 SUMMARY
This thesis focuses on reciprocating air compressor for commercial vehicle and we
described existing design (Includes basic thermodynamics) in the first chapter.
Our study of existing design was conducted technically referring to benchmarking of total
12 compressors (6 European air compressor and 6 Asian air compressors).
As we move forward in our study, we understood detailed knowledge for reciprocating air
compressor in commercial vehicle, exploring the area of applications gives us more
understanding related to complexity of the system, once we know the areas of application, we
did a market study with help of Nabtesco ITG Germany and Minda Nabtesco automotive Pvt. Ltd.
And collected the data related to fields issue and problem faced during assembly, repair and
maintenance of reciprocating air compressor. As a result of this study we were able to identify
following problems:
1. Oil carry over,
2. Heavy carbon deposit in supply tubes,
3. Melt down of moisture absorbing desiccant,
4. Noise,
The above-mentioned problems resulted in heavy damage to vehicle and loss due to
immobility of vehicle in commercial transportation sector, a rough anticipation was made on
considerable factors and amount of loss to owner was ~10,000 Euros/ year.
Hence, we continued our study related to compressor designing including reverse
engineering of above mentioned 12 reciprocating air compressor and after learning some basic
calculations and other trial and development data from Nabtesco ITG, we finally developed a
mathematical model for a compressor which will overcome problems and resulted in:
1. High efficiency,
2. Low oil carry over,
As we move to next step for material selection and heat transfer, we made a drastic
change in material. Existing designs use crankcase and cylinder made up of cast iron (especially
Asian models) but we decided to move forward with integrated aluminium crankcase and cylinder
with iron liner and also implemented energy saving system with the cylinder head (improvised
design for maximum air flow) and the result of above changes were very good and positive such
as:
1. Light weight (25-30% reduced than existing design),
2. Better Fuel economy,
3. Lower discharge air temperature due to better heat exchange,
Page 86 of 93

Also changing the material of sealing elements and gaskets for more effective options
resulted to improve losses section.
All the above-mentioned changes and mathematical model was the recommendations
which will be tried in near future.
With this we developed a concept for a technically advanced reciprocating air compressor
and its physical functionality can be checked by the tests mentioned in chapter number 6 in
details.
Page 87 of 93

BIBLIOGRAPHY
[1] N. G. S. R. a. K. S. Venkatesan J, “Mathematical Modeling of Water Cooled
Automotive Air Compressor,” International Journal of Engineering and Technology,
vol. 1, no. 1793-8236 , pp. 50-56, 2009.
[2] V. J. S. R. V. a. M. R. Nagarajan GOVINDAN, “MATHEMATICAL
MODELING AND SIMULATION OF A REED VALVE RECIPROCATING AIR
COMPRESSOR,” THERMAL SCIENCE, vol. 13, no. 2009, pp. 47-58, 2009.
[3] Prasanna, “Engineering Hub,” 13 10 2009. [Online]. Available:
https://www.engihub.com/compressor-terminology/.
[4] T. E. T. Box, “Type of Air compressor,” 2003. [Online]. Available:
https://www.engineeringtoolbox.com/air-compressor-types-d_441.html.
[5] P. D.-I. H.-J. K. &. P. D.-I. H. G. Will, Grundlagen der Kolbenmaschinen,
Technical University of Dresden.
[6] WABCO, “Inform.wabco-auto.com,” WABCO, [Online]. Available:
http://inform.wabco-auto.com/intl/pdf/815/00/03/8150100033t1.pdf.
[7] European Braking System, “European Braking System,” [Online]. Available:
https://www.europeanbrakingsystems.co.uk/history.
[8] G. R. &. B. N. VADITHE, “Design and analysis of Connecting rod,”
International Journal of research, vol. 6, no. 1 May 2017, pp. 240-251, 2017.
Page 88 of 93

List of images
Figure 1: A typical air compressor ................................................................................................ 9
Figure 2: Rotary type air compressor ........................................................................................... 9
Figure 3: Reciprocating air compressor (Single acting) ............................................................. 11
Figure 4: Piston-moving inside the cylinder ............................................................................... 11
Figure 5: Double-acting compressor .......................................................................................... 13
Figure 6: p-V diagram for a reciprocating compressor without clearance ................................. 14
Figure 7: p-V diagram for a reciprocating compressor with clearance ...................................... 15
Figure 8: Indicator diagram for a 2-stage machine .................................................................... 16
Figure 9: p-V diagram for effect of increase delivery pressure on the volume of fresh air induced
.................................................................................................................................................... 16
Figure 10: p-V diagram for effect of increase delivery pressure on the volume of fresh air induced
.................................................................................................................................................... 16
Figure 11: Trunk piston compressor .......................................................................................... 18
Figure 12: Crosshead type piston compressor .......................................................................... 18
Figure 13: Commercial Vehicle .................................................................................................. 21
Figure 14: Typical commercial vehicle compressor fluid flow .................................................... 22
Figure 15: Air braking system in a commercial vehicle .............................................................. 22
Figure 16: Components of a Commercial Vehicle reciprocating compressor of single stage ... 23
Figure 17: Inlet and Delivery disc valve openings ...................................................................... 26
Figure 18: Inlet and Delivery disc valve openings ...................................................................... 27
Figure 19: Terminology Diagram 1 ............................................................................................. 28
Figure 20: Terminology Diagram 2 ............................................................................................. 29
Figure 21: Air Dryer (component of air braking system) ............................................................ 41
Figure 22: Multi Circuit Protection Valve (component of air braking system) ............................ 42
Figure 23: Air Tank (component of air braking system) ............................................................. 42
Figure 24: Dual Brake Valve (component of air braking system) .............................................. 43
Figure 25: Brake chamber (component of air braking system) .................................................. 44
Figure 26: Spring Brake Actuator (component of air braking system) ....................................... 45
Figure 27: Trailer control valve ................................................................................................... 47
Figure 28: Suspension system ................................................................................................... 47
Figure 29: Pressure Gauge ........................................................................................................ 48
Figure 30: Hand controlled Brake valve ..................................................................................... 49
Figure 31: Tyre Inflator ............................................................................................................... 50
Figure 32: Shaft With Through Drive Feature ............................................................................ 50
Figure 33: Bore ........................................................................................................................... 55
Figure 34: Stroke ....................................................................................................................... 56
Figure 35: Displacement (Sweep Volume) ................................................................................ 56
Figure 36: Clearance Volume .................................................................................................... 57
Figure 37: Stroke and crank radius ............................................................................................ 59
Page 89 of 93

Figure 38: Crank angle and length ............................................................................................. 60
Figure 39:Stack-up diagram ....................................................................................................... 62
Figure 40: Exploded view .......................................................................................................... 63
Figure 41:input for gasket .......................................................................................................... 75
Figure 42: Gasket shape ............................................................................................................ 76
Figure 43: Torque line for gaskets ............................................................................................. 77
Figure 44: Silicone on gaskets ................................................................................................... 78
Figure 45: Thickness for gaskets ............................................................................................... 78
Figure 46: Test Circuit for leak and performance testing ........................................................... 82
Figure 47: Fujifilm impression .................................................................................................... 83
Page 90 of 93

List of Table
Table 2.1: Conclusion derived from technical comparison ......................................................... 38
Table 4.1: Design Features used for problem-solving ................................................................ 53
Table 5.1 Bore and stroke comparison for relevant selection ..................................................... 54
Table 5.2: Stack up calculation for crankcase centre to cylinder ................................................ 61
Table 5.3: Step in Solidworks for designing of connecting rod: -................................................ 64
Table 5.4: Suitable materials for connecting rod ......................................................................... 66
Table 5.5 : Ansys simulation for connecting rod ......................................................................... 67
Table 5.6: Result :Structural Analysis ......................................................................................... 74
Table 5.7: Result :Model Analysis ............................................................................................... 74
Table 5.8: Material selection for gaskets..................................................................................... 76
Table 7.1: History for application of compressors in vehicle ....................................................... 85
Page 91 of 93

APPENDICES A
Compressor-Technical Comparison Sheet
S no. Parameters A B C
1
Type No./ Special
No.
M101670 M101480 M100750
2 Displacement (cm³) 160 160 160
3 Cooling (Air/Water) Air Air Air
4
Operating Pressure
(bar)
8 8 8.25
5 Bore (Ø) 66.7 66.7 80
6 Stroke (mm) 46 46 32
7 Max. Speed (R.P.M) 3000 3000 1800
8 Weight (Kg) 6.79 6 9
9 Mounting
Base Mounting
2 X M10x1.5 ↧ 13
Torque 42±5 Nm
Flange Mounting
Flange Mounting
10 Drive (Gear/Belt) Belt Belt Gear
11 Aftermarket/ OEM AM AM AM
12 ESS/ Clutch No No No
13 Through Drive No No No
17
Oil Inlet Port(s)
Port No.- 8.1
M10x1.5
Depth (↧) 15mm
Torque 16±2Nm
M10x1.5
Depth (↧) 15mm
Torque 16±2Nm
M10x1.5
Depth (↧) 13mm
Torque 16±2Nm
18
Oil Delivery Port(s)
Port No.- 8.2
M22x1.5
Depth (↧) 14mm
Torque 48±5Nm
Through Flange
Through Flange
19
Air Inlet Port(s)
Port No.- 0
M26x1.5
Depth (↧) 12min.
Torque 60±7Nm)
M22x1.5
Depth (↧) 15mm
Torque 50.5±2.5Nm
M22x1.5
Thread Length 15 mm
Torque 48±5Nm
20
Air Delivery Port(s)
Port No.- 2
M22x1.5
Thread Length 15 mm
Torque 48±5Nm
M22x1.5
Depth (↧) 15mm
Torque 50.5±2.5Nm
M22x1.5
Thread Length 15 mm
Torque 48±5Nm
21
Water Port(s)
Port No.- 9.1<In>
Port No.- 9.2<Out>
No Water Port(s) No Water Port(s) No Water Port(s)
22
Control Port(s)
Port No.- 4
M12x1.5
Depth (↧) mm
Torque 19±2Nm
No control port
No control port
Page 92 of 93

APPENDICES B
Page 93 of 93
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