Slant plate type compressor with variable displacement mechanism

Claim 1

A slant plate type refrigerant compressor for use in a refrigerant circuit comprising: 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, said rear end plate having a suction chamber and a discharge chamber; 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 to vary the stroke length of said pistons and the capacity of said compressor; and a control device to vary the capacity of said compressor by adjusting the incline angle, said control device including at least one passageway communicating between said crank chamber and said suction chamber and two control means for controlling the pressure in said crank chamber by opening and closing said at least one passageway, said first control means controlling the pressure in said crank chamber responsive to the pressure in said suction chamber, and said second control means controlling the pressure in said crank chamber responsive to the temperature of refrigerant in said suction chamber, wherein said second control means comprises a mechanism that operates directly in response to the temperature of refrigerant in said suction chamber absent external inputs.