Patent ID: 7563078

Claim:
A reciprocating compressor, comprising: a low-pressure stage compression part for compressing low-pressure working gas supplied from a supply source; two high-pressure stage compression parts for compressing the working gas compressed by the low-pressure stage compression part at two stages; and a crank mechanism for driving the low-pressure stage compression part and the high-pressure stage compression parts, wherein the two high-pressure stage compression parts each have a plunger and a cylinder and are arranged on both sides of the crank mechanism in such a way as to extend coaxially opposite to each other, wherein the low-pressure stage compression part has a piston and a cylinder and is arranged in the middle of the two high-pressure stage compression parts in such a way as to extend, wherein the crank mechanism includes: an eccentric shaft part that is provided eccentrically in a main shaft part of the crankshaft; a low-pressure stage cross head that is coupled to the piston via a piston rod; a low-pressure stage connecting rod has one end of which is coupled to the eccentric shaft part and the other end of which is coupled to the low-pressure stage cross head; a high-pressure stage cross head that is coupled to the two plungers via respective plunger rods; a high-pressure stage connecting rod has one end of which is coupled to the eccentric shaft part and the other end of which is coupled to the high-pressure stage cross head, is arranged in such a way as to move in a horizontal direction and has an opening formed through its top frame part in a vertical direction; the high-pressure stage cross head is formed in a shape of one nearly rectangular frame, the eccentric shaft part, the low-pressure stage connecting rod, and the high-pressure stage connecting rod are arranged in the frame of the high-pressure stage cross head, the high-pressure stage cross head has an opening formed through its top frame part in a vertical direction, the low-pressure stage connecting rod is passed through the opening and is coupled to the eccentric shaft part and the low-pressure stage cross head, and the crank mechanism, the low-pressure stage compression part, and the two high-pressure stage compression parts are arranged in such a way that they are substantially located in a same plane.