Slant plate type compressor with variable displacement mechanism

In a slant plate type refrigerant compressor for use in a refrigeration circuit, said compressor including a compressor housing having a central portion, a front end plate at one end and a rear end plate at its other end, said housing having a cylinder block provided with a plurality of cylinders and a crank chamber adjacent said cylinder block, a piston slidably fitted within each of said cylinders, a drive mechanism coupled to said pistons to reciprocate said pistons within said cylinders, said drive mechanism including a drive shaft rotatably supported in said housing, a rotor coupled to said drive shaft and rotatable therewith, and coupling means for drivingly coupling said rotor to said pistons such that the rotary motion of said rotor is converted into reciprocating motion of said pistons, said coupling means including a member having a surface disposed at an incline angle relative to said drive shaft, said incline angle of said member being adjustable in response to changes in the crank chamber pressure to vary the stroke length of said pistons and the capacity of the compressor, said rear end plate having a suction chamber and a discharge chamber, a passageway connected between said crank chamber and said suction chamber, and a variable displacement mechanism for controlling the closing and opening of said passageway to control communication between said suction and said crank chambers to vary the capacity of said compressor by adjusting the incline angle, said variable displacement mechanism including a valve control mechanism to directly open and close said passageway, the improvement comprising:

• said valve control mechanism comprising a first valve control device, said first valve control device comprising a first valve element for controlling the opening and closing of said passageway, and an isolated pressure sensitive chamber within which said first valve element is partially disposed and which controls said first valve element;
• and
• a second valve control device to control the communication between said suction chamber and said isolated pressure sensitive chamber in accordance with changes in operating conditions of said compressor.