Variable displacement compressor

Claim 1

An axial piston, variable displacement, wobble plate compressor with a plurality of gas working spaces and corresponding plurality of pistons, each positioned in one of said spaces, a drive shaft having a central, cylindrical portion disposed along a longitudinal axis, at least one thrust flange member extending radially from said cylindrical portion and defining a shoulder at the junction with said cylindrical portion, a hinge ball defining a bore to receive the drive shaft and be slidable thereon, a wobble plate and hub assembly with said hinge ball mounted in said hub which hub defines a pin bore and counterbore, means operably connected between said wobble plate and pistons to impart reciprocating drive to said pistons, said compressor stroke being responsive to pressure differentials across said pistons between an inoperative mode and a range of operative modes, wherein the improvement comprises a positive stop pin mounted in said pin bore and counterbore and a piston-stroke-decreasing spring mounted on said drive shaft between said hinge ball and said shoulder at the junction of said thrust flange member and the cylindrical portion of said drive shaft, said stop pin maintaining said wobble plate and hinge ball assembly at about 0.100 inch piston stroke in an inoperative mode of said compressor, said piston-stroke-decreasing spring acting as the sole bias means on said hinge ball during the inoperative mode with the exception of said pressure differential across said pistons.