Patent ID: 6446451
Filing Date: 2002-09-10
Classification: F04B

Abstract:
A two stage reciprocating compressor comprising:a block with a single cylinder and associated single compression chamber and single piston; a crankshaft having an eccentric crankpin, the eccentric crankpin operatively connected to the piston; a reversible motor operable to rotate the crankshaft in a forward direction and in a reverse direction; and an eccentric cam rotatably mounted on the eccentric crankpin, the cam held stationary at a first position with respect to the crankpin when the crankshaft is rotating in the forward direction to drive the piston at a full stroke between a bottom position and a top dead center position, the cam rotating to a second position with respect to the crankpin when the crankshaft is rotating in the reverse direction to drive the piston at a reduced stroke between an intermediate position and the top dead center position, wherein the eccentricities of the crankpin and the cam combine to move the piston through the full stroke when the motor is rotating in the forward direction and to move the piston through the reduced stroke when the motor is rotating in the reverse direction, wherein the eccentricities of the cam and the crankpin are chosen so that the capacity of the compressor is switched from full to approximately one half, upon reversing of the motor.