Slant plate type compressor with variable displacement mechanism

Claim 1

A slant plate type compressor for use in a refrigeraton circuit, the compressor including a compressor housing (2) having a front end plate (3) at one end of the housing and at the other end of the housing a rear end plate (4) in the form of a cylinder head defining a suction chamber (40) and a discharge chamber (41), the housing having a cylinder block (21) provided with a plurality of cylinders (24) and a crank chamber (22) adjacent to the cylinder block; a plurality of pistons (14) slidably fitted within respective ones of the cylinders; a drive mechanism coupled to the pistons to reciprocate the pistons within the cylinders, the drive mechanism including a drive shaft (6) rotatably mounted in the housing, a rotor (10) coupled to the drive shaft and rotatable therewith, and coupling means (11,12,15) for coupling the rotor to the pistons such that the rotary motion of the rotor is converted into reciprocating motion of the pistons, the coupling means including a member (11) having a surface disposed at an inclination relatively to the drive shaft, and the angle of inclination of the member being adjustable to vary the stroke length of the pistons and the capacity of the compressor; a first bypass passage (25,26,52) connected between the crank chamber (22) and the suction chamber (40); and first valve means (171,172) for controlling the closing and opening of the first bypass passage in response to changes in refrigerant pressure in the compressor to vary the capacity of the compressor by adjusting the angle of inclination; characterised by a second bypass passage (27,53) connected between the crank chamber and the suction chamber; and second valve means (18) for controlling the closing and opening of the second bypass passage in response to an external signal to vary the capacity of the compressor by adjusting the angle of inclination.