Patent ID: 6425254
Filing Date: 2002-07-30
Classification: B60H,F04B

Abstract:
A displacement control device for a compressor that draws and compresses refrigerant gas and changes the displacement in accordance with the pressure in a controlled pressure chamber, comprising:a control valve for controlling the pressure in the controlled pressure chamber, the control valve having a valve body, a pressure sensing mechanism and an electromagnetic actuator, wherein the pressure sensing mechanism displaces the valve body in accordance with the pressure of refrigerant gas drawn into the compressor, and wherein the electromagnetic actuator adjusts a force applied to the valve body based on the value of a current supplied to the electromagnetic actuator, thereby changing a target suction pressure, which is a reference value for the operation of the pressure sensing mechanism; a detector for detecting the pressure of refrigerant gas that is drawn into the compressor; and a controller, wherein the controller selects a control procedure from a normal displacement control procedure and a temporary displacement control procedure based on the suction pressure detected by the detector, wherein, when the normal displacement control procedure is selected, the controller sends a current, the value of which is based on external information, to the electromagnetic actuator, and, when the temporary displacement control procedure is selected, the controller sends a current having a specific value to the actuator to maximize the target suction pressure, wherein, when switching from the temporary displacement control procedure to the normal displacement control procedure, the controller changes the value of the current supplied to the electromagnetic actuator in a predetermined pattern over a predetermined period, and determines characteristics of the pattern based on the detected pressure during or at the end of the temporary displacement control procedure.