3. Capacity Control
=NBHA0087S0203
I
Refrigerant pressure on suction side is low during high speed driving or when ambient or interior tempera-
ture is low.
I
The bellows expands when refrigerant pressure on the suction pressure side drops below approximately
177 kPa (1.8 kg/cm
2
, 26 psi).
Since suction pressure is low, it makes the suction port close and the discharge port open. Thus, crank-
case pressure becomes high as high pressure enters the crankcase.
I
The force acts around the journal pin near the swash plate, and is generated by the pressure difference
before and behind the piston.
The drive lug and journal pin are located where the piston generates the highest pressure. Piston pres-
sure is between suction pressure Ps and discharge pressure Pd, which is near suction pressure Ps. If
crankcase pressure Pc rises due to capacity control, the force around the journal pin makes the swash
plate angle decrease and also the piston stroke decrease. In other words, crankcase pressure increase
triggers pressure difference between the piston and the crankcase. The pressure difference changes the
angle of the swash plate.
RHA474C
DESCRIPTION
V-6 Variable Displacement Compressor (Cont’d)
HA-18