About Compressors :
1)Rotary vane compressors consist of a rotor with three or four
vanes and a carefully shaped
rotor housing. As the compressor shaft rotates, the vanes and
housing form chambers.
The R134a is drawn through the suction port into these chambers,
which become smaller as
the rotor turns. The discharge port is located at the point where
the gas is fully compressed.
The vanes are sealed against the rotor housing by centrifugal force
and lubricating oil. The
oil sump and oil pump are located on the discharge side, so that
the high pressure forces oil
through the oil pump and then onto the base of the vanes keeping
them sealed against the
rotor housing.
During idle an occasional vane noise from the compressor may be
heard. This is due to the
time taken for lubricating oil to circulate through the A/C system.
2)Scroll type - Sanden
This compressor uses a unique design with two scrolls, one fixed
and one is movable, both are inter-leaved.
The movable spiral is able to ORBIT or oscillate without actually
fully rotating. The movable scroll is connected
to the input shaft via a concentric bearing.
As the movable spiral oscillates within the fixed spiral, a number
of pockets are formed between the spiral. As
these pockets decrease in size the refrigerant is squeezed, the
pressure increases and is discharged
through a reed valve at the discharge port in the rear section of
the compressor.
3)Variable stroke - Harrison V5
The Delphi (Harrison) V5 compressor is a non-cycling variable
displacement compressor.
The compressor varies displacement to control capacity to meet A/C
system demand at all operating conditions. The compressor features
a variable angle wobble plate in five (V5) cylinder axial piston
design.
Displacement is controlled by a bellows actuated control valve
located in the rear cylinder head. This control valve senses and
responds to the system suction pressure or A/C system demand.
Through regulation of compressor crankcase pressure, the wobble
plate angle, and therefore compressor displacement is variable.
In general, the compressor discharge pressure is much greater than
the compressor crankcase. Which is greater than or equal to the
compressor suction pressure.
At maximum displacement, compressor crankcase pressure is equal to
the compressor suction pressure.
At reduced or minimum displacement, the compressor crankcase
pressure is greater than the suction pressure