General
The variable compressor is basically a swash plate type that changes piston stroke in response to the required cooling capacity.
The tilt of the wobble (swash) plate allows the piston's stroke to change so that refrigerant discharge can be continuously changed from 14.5 to 184 cm 3 (0.885 to 11.228 cu in).
Scheme 161
Scheme 162
Scheme 163
- Operation 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 loft is determined by factors below. Low pressure applied to diaphragm Spring load of set spring Balance of magnetic force generated in magnet coil Electronic control valve (ECV) magnet coil receives electric signal (duty control) from auto amplifier. Then, magnetic force generated by electric current is changed to control high-pressure valve lift amount.
- Maximum Cooling High-pressure valve is closed by magnetic force generated by electric signal sent from automatic amplifier. 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 automatic amplifier (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 near 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.
