RevisionC-Developmentofconceptofcompressorforcommercialvehicle

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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