Patent ID: 7014428

Claim:
A variable displacement compressor, comprising: a compressor housing having a crankcase chamber with a crankcase pressure, a suction chamber with a suction pressure, and a discharge chamber with a discharge pressure, an oil separator in a discharge line of the compressor, the compressor also having a driveshaft, a swashplate connected to and driveable by the driveshaft, a plurality of pistons connected to the swashplate and reciprocating in a plurality of cylinders, wherein a displacement of the compressor is varied by the angle of the swashplate with the drive shaft; and a three-way control valve having a valve body, a valve stem, at least one spring opposing motion of the valve stem, and three chambers in series for receiving three pressures from the variable displacement compressor, one chamber receiving a discharge pressure, one chamber receiving a crankcase pressure, and one chamber receiving an auxiliary pressure from the oil separator, wherein the control valve is operative to change the crankcase pressure and thereby change the displacement of the compressor.