Control valve for variable displacement compressor

Abstract: To provide a control valve for variable displacement compressor employing ON/OFF control, which is capable of taking measures for occurrence of an abnormally high pressure. When a solenoid is OFF, a spring causes a movable core to move a stopper in a direction away from a stationary core and to thereby separate a shaft fixed to the stopper from a valve seat, resulting in opening the control valve. When the solenoid is ON, the movable core is attracted by the stationary core by a stroke longer than that of the shaft, and a spring causes the shaft to seat on the valve seat, resulting in closing the control valve. If a discharge pressure Pd increases to an abnormally high pressure, a differential pressure between the discharge pressure Pd and a pressure Pc in a crankcase pushes the shaft while compressing the spring, so that the discharge pressure Pd flows out to the crankcase. Therefore, the pressure Pc in the crankcase increases and the variable displacement compressor shifts to operate at a minimum discharge capacity, resulting in decreasing the abnormally high pressure. (end of abstract)