Scroll type refrigerant compressor

A scroll type refrigerant compressor adapted for use in a refrigerating system of an automobile in which the compressor comprises:

• an axial housing means forming an outer casing of the compressor and defining a refrigerant suction passage means, including a suction chamber, a discharge chamber, a low pressure chamber provided around said discharge chamber, and a passage for a fluid communication between the low pressure chamber and the suction chamber, the housing means having a longitudinal axis extending at substantially the center portion thereof;
• a drive shaft held within the axial housing means for rotation about the longitudinal axis;
• a stationary scroll means fixedly encased in the housing means and having a stationary spiral member and a stationary end plate member attached to an end of said spiral member;
• a movable scroll means engaging the stationary scroll means and moving along a predetermined orbiting path respective to the stationary scroll means according to the rotation of the drive shaft, the stationary and movable scroll means defining compression chambers therebetween, the compression chambers shifting from the periphery to the center of the scroll means by the orbiting motion of the movable scroll means, the stationary end plate member including at least a relief port for fluid communication between the compression chambers and the low pressure chamber;
• a valve plate member in the form of a ring which includes at least a valve port and is rotatable about the axis of the housing means between an open position where the valve port is aligned with the relief port to provide fluid communication between the compression chambers and the low pressure chamber and a closed position where the valve port separates the compression chamber from the low pressure chamber;
• a means for generating a refrigeration demand signal to operate the compressor;
• an actuator means for rotating the valve plate member between the open position and the closed position in response to the refrigeration demand signal, the actuator means comprising a cylinder attached to the housing means and having a distal end chamber and a proximal end chamber therein, a piston slidably provided in the cylinder and outwardly extending from the distal end of the cylinder and a spring in the proximal end chamber for biasing the piston toward the distal end of said cylinder;
• a control valve having a first pressure port fluidly connected to the discharge chamber, a second pressure port fluidly connected to the low pressure chamber, and a control port fluidly connected to the proximal end chamber of said cylinder;
• and
• a means for controlling the control valve in a first position to supply refrigerant gas from the discharge chamber to the proximal end chamber of said cylinder in response to the refrigeration demand signal, and in a second position to supply refrigerant gas from the low pressure chamber to the proximal end chamber.