V-6 Variable Displacement Compressor: Description: Operation
WARNING: This page is about a different car, the 2006 Infiniti G35. However, it is still accessible from the selected car via links, so may be relevant.
- Control Valve
- By changing high-pressure valve lift amount, built-in compressor control valve executes the following:
- Controls high-pressure valve discharge amount.
- Changes crankcase pressure in compressor.
- Changes angle of wobble (swash) plate.
- Amount of high-pressure valve lift is determined by factors below.
- Low-pressure applied to diaphragm
- Spring load of set spring
- Balance of magnetic force generated by magnet coil
- Electronic control valve (ECV) magnet coil receives electric signal (duty control) from display and A/C auto amp. Then, magnetic force generated by electric current is changed to control high-pressure valve lift amount.
- By changing high-pressure valve lift amount, built-in compressor control valve executes the following:
- Maximum Cooling
High-pressure valve is closed by magnetic force generated by electric signal sent from display and A/C auto amp. At this time, cylinder moves full stroke due to pressure balance between inside crankcase (Pc) and suction line (Ps).
Under this condition, the wobble (swash) plate is set to the maximum stroke position.
- Capacity Control
When no electric signal is sent from display and A/C auto amp. (current: OFF), high-pressure valve is opened by spring force.
Since suction pressure is low, it makes the suction port close and the discharge port open. Thus, crankcase pressure becomes high as high-pressure enters the crankcase.
- The force acts around the journal pin near the wobble (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 pressure is between suction pressure Ps and discharge pressure Pd, which is close to suction pressure Ps. If crankcase pressure Pc rises due to capacity control, the force around the journal pin makes the wobble (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 wobble (swash) plate.