UWE Bristol Engineering showcase 2015

Sebastian Gibbs
BEng Motorsport Engineering
Supervisor: Changho Yang
Investigation of Cam lobe design and their effect on performance
Mathematical Function analysis
The first step of the investigation was
understanding the use of mathematical functions
that can be used to create the parabolic like
profiles that are the geometry of the cam. Multiple
functions were investigated and the resulting
appropriate function were both polynomial, the
first being a 6 th order polynomial and another
being a 7 th order polynomial.
Displacement/ mm
14
12
10
8
6
4
2
0
Lift profile for intake valve of high cam using 6th and 7th order
polynomial
0 50 100 150 200 250 300
Crank Angle (θ)/deg
7th order
6th order
original
Simulation and analysis
As discussed in the summary, the use of 1-d
simulation, and preprogrammed cam profiles to
improve, were utilized in the study. To investigate
the flow properties of valve motion, and thus the
cam lobe profile, the simulation was run with
having various profiles contracted by the
polynomial curves. Using the outputs of the
simulation such as, mass flow rate at valves and
effective area, analysis's were made to link the
flow parameters with geometrical properties of
the cam lobe and by doing so find where the areas
for improvement are and how that can be
improved
Design changes outcome
From the preprogramed lift profiles and timing
an original cam profile was created along with a
timing diagram (left), from the information
gained form the experiment and its results a
new geometry for a cam lobe along with new
timing diagram was generated (right). A total of
16% increase in power was generated by the
new profile.
ss = h 64
ss = h 35
Mass Flow/ Kg/Hr
θθ ββ
θθ ββ
3
− 192
4
430
330
230
130
30
-70
− 84
θθ ββ
θθ ββ
4
5
+ 192 θθ ββ
+ 70 θθ ββ
Mass Flow Rate intake Valve
6
5
+ 64 θθ ββ
− 20
-180 -80 20 120 220 320 420 520
Crank Angle (θ)/deg
θθ ββ
7
6
Original
Lift
Duration
Advance
Project summary
The aim of the project was to investigate the effects
of cam lobe design on an engines performance. By
means of mathematical derivations for lobe profile
functions and 1-d simulation, valve displacement
profiles generated and introduced into the simulation
and the resulting performance figures analysed
Project Objectives
1. Investigate how power production can be
increased due to geometrical modification of the
camshaft.
2. Investigate the use of mathematical formulae used
in cam design.
3. Using a simulation software, with base engine, run
test and analyse data for development.
4. Generate model of new cam lobe design for
improved power performance.
Project Conclusion
How an engine breathes is directly linked to the power it
can produce, so by analyzing the flow through the engine
improvements can be made to the flow via cam lobe
design. Generating cam profiles is a important area of
investigation when undergoing cam design, as the
functions themselves will produce vastly different dynamic
characteristics. Once appropriate functions have been
created simulation is needed to understand how these
function effect the flow of gases through the valves. By
finding imperfections or undesirable elements of the flow
process gives indictors for how the flow can be improved,
linking these elements to geometrical features of the cam
lobe design is key to generating a better cam for power
production in an engine.
Initial
Final Cam
INDIC.POWER[hp]= 30.19 INDIC.POWER[hp] = 35.05