Patent ID: 7614251

Claim:
A reciprocating compressor comprising: a casing; a frame elastically supported in an inner space of the casing; a reciprocating motor including an inner stator and an outer stator fixed on the frame, and a linearly-movable mover inserted between the inner stator and the outer stator; a two-stage cylinder, mounted at the frame, having first and second cylinder bores of different diameters with a stepped surface therebetween; a two-stage piston, having a first piston portion and a second piston portion having diameters corresponding to the diameters of the first and second cylinder bores, the first and second piston portions linearly-reciprocating in the same direction in the two-stage cylinder by the driving force of the reciprocating motor so as to simultaneously suck, compress and discharge refrigerant; a resonant spring that causes the two-stage piston to move in a resonant motion; a first suction valve and a first discharge valve, respectively disposed at an inlet and an outlet of a first compression space formed by the first piston portion and the first cylinder bore; a second suction valve and a second discharge value, respectively disposed at an inlet and an outlet of a second compression space formed by the second piston portion and the second cylinder bore; a first suction pipe that is connected at an inlet side of the first compression space and extends through the casing; a second suction pipe that is connected at an inlet side of the second compression space and extends through the casing; and a discharge pipe that is connected at an outlet side of the second compression space and extends through the casing, wherein refrigerant is directly introduced into the first compression space through the first suction pipe, the refrigerant is compressed in the first compression space and discharged into the inner space of the casing, the compressed refrigerant is introduced into the second compressed space and mixed with other refrigerant which is directly introduced into the casing through the second suction pipe, and the mixed refrigerant in the second compression space is discharged outside of the casing through the discharge pipe.