Patent ID: 6672844
Filing Date: 2004-01-06
Classification: F04B

Abstract:
A refrigerant circuit of an air conditioner, comprising:a compressor, wherein the compressor includes: a crank chamber having a pressure; a drive shaft; a reciprocating piston; and a tiltable drive plate, which is located in the crank chamber and converts rotation of the drive shaft to reciprocation of the piston, the drive plate changes its inclination angle in accordance with the pressure in the crank chamber, and wherein the drive plate changes the stroke of the piston according to the inclination angle of the drive plate thereby changing the displacement of the compressor; an external circuit, which is connected to the compressor, wherein the compressor compresses refrigerant sent from the external circuit and discharges the compressed refrigerant to the external circuit; a high pressure zone, which is exposed to the pressure of refrigerant that is compressed by the compressor; a pressure sensor for detecting the pressure in the high pressure zone; a control valve, which adjusts the pressure in the crank chamber; and a controller for controlling the control valve, wherein the controller sends a command value that corresponds to cooling performance required for the refrigerant circuit to the control valve, wherein the control valve operates to adjust its opening according to the sent command value, wherein, when the pressure in the high pressure zone is equal to or higher than a predetermined threshold value, the controller executes a limiting control for limiting the pressure in the high pressure zone, wherein, during the limiting control, the controller first gradually changes the command value, which is sent to the control valve, such that the displacement of the compressor is gradually decreased, and then, when the command value is equal to a predetermined reference value, the controller sends a command value that can minimize the displacement of the compressor to the control valve.