Capacity control arrangement for a variable capacity wobble plate type compressor

A capacity control arrangement for a variable capacity wobble plate type compressor used for air-conditioning an engine driven car and provided with a drive shaft connectable to the car engine, a crankcase having a chamber for receiving an assembly of rotatable drive and non-rotatable wobble plates mounted on the drive shaft to cause a reciprocation of compressing pistons in response to the rotation of the drive shaft, a cylinder block having cylinder bores therein for the compressing pistons, a suction chamber for a refrigerant gas before compression, a discharge chamber for the compressed refrigerant gas, and a solenoid-operated valve for controlling a fluid communication between the crankcase and discharge chambers to thereby control a pressure level in the crankcase chamber in such a manner that an inclination of the wobble plate is changed to vary the capacity of the compressor, comprising, in combination:

• a first detecting means for detecting a pressure of the compressed gas discharged from said variable capacity wobble plate type compressor;
• a second detecting means for detecting a load on said car engine;
• a first control means connected to said first and second detecting means for controlling the operation of said solenoid-operated valve in such a manner that said solenoid-operated valve takes a fully open position to establish a complete fluid communication between said crankcase chamber and said discharge chamber to thereby bring the inclination of said wobble plate to a position for a lowest capacity of said compressor by the introduction of the compressed gas of a high pressure from said discharge chamber to said crankcase chamber when the load on said car engine detected by said second detecting means exceeds a predetermined level;
• a time setting means for setting a time for which said solenoid-operated valve is maintained at the fully open position in relation to the pressure of the compressed gas detected by said first detecting means;
• and
• a second control means also connected to said first and second detecting means for controlling the operation of said solenoid-operated valve in such a manner that said solenoid-operated valve is moved from the fully open position to a given reduced opening position suitable for maintaining the pressure in said crankcase chamber at a level capable of maintaining the lowest capacity of said compressor for a time from the elapse of the time set by said time setting means to a detection of a reduction in the engine load below the predetermined level by said second detecting means.