A gas pressure increasing system having at least a scroll compressor, an exhaust conduit, a condenser, a pressure reducing means, an evaporator and a suction conduit, said scroll compressor comprising:
- a fixed scroll member including an end plate, a wrap attached to one surface of said end plate in an upstanding position and primarily formed in an involute curve, an exhaust port formed in said end plate in a position close to a commencing end of said wrap, and a suction port formed in said end plate in a position close to a terminating end of said wrap;
- an orbiting scroll member including an end plate, and a wrap attached to one surface of said end plate in an upstanding position and primarily formed in an involute curve, said orbiting scroll member and said fixed scroll member being arranged in juxtaposed relation with the wraps thereof being fitted closely together;
- means for inhibiting the rotation of said orbiting scroll member on its own axis;
- a housing means attached to said surface of said end plate of said fixed scroll member which has said wrap and including a housing chamber for containing therein said orbiting scroll member, said housing means being formed with at least two communicating ducts;
- at least one bearing secured to said housing means;
- a drive shaft supported by said bearing;
- a balancing weight;
- a pin attached to said drive shaft in a position remote from the center axis of said drive shaft for transmitting the rotation of said drive shaft from said positon to said orbiting scroll member as an orbiting motion;
- and
- a motor connected to said drive shaft;
- wherein the improvement comprises:
- a branch conduit branching, at one end thereof, off a refrigerant path from a point therein immediately posterior to the condenser and mounting a pressure reducing means midway thereof for reducing the pressure of a refrigerant to an intermediate pressure level and expanding the same so as to cause the refrigerant in the form of a gas of an intermediate pressure level to act on a surface opposite to the surface provided with said wrap of said end plate of said orbiting scroll member of said scroll compressor;
- and
- means for returning the refrigerant in the form of a gas acting on said opposite surface of said orbiting scroll member of said scroll compressor to sealed spaces of an intermediate pressure level defined between said fixed scroll member and said orbiting scroll member.