Patent ID: 8475149

Claim:
A scroll fluid machine comprising: a sealed vessel; a first fixed scroll that is disposed so as to partition off an upper portion space inside said sealed vessel, and in which a first spiral tooth and a first spiral groove are formed on a lower surface of a first base plate; an orbiting scroll that is configured such that an upper spiral tooth and an upper spiral groove, and a lower spiral tooth and a lower spiral groove, are formed on two surfaces of a third base plate, and that is disposed so as to face a lower surface side of said first fixed scroll such that said upper spiral tooth intermeshes with said first spiral tooth; a second fixed scroll that is configured such that a second spiral tooth and a second spiral groove are formed on an upper surface of a second base plate, that is disposed so as to face a lower surface side of said orbiting scroll such that said second spiral tooth intermeshes with said lower spiral tooth, and that partitions off a lower portion space inside said sealed vessel; a main shaft that is disposed so as to be rotatably supported by a first shaft bearing portion of said first fixed scroll and a second shaft bearing portion of said second fixed scroll, and so as to pass through a boss portion of said orbiting scroll, and that makes said orbiting scroll perform orbital motion, wherein said orbiting scroll compresses or expands a working fluid on each of an upper surface side and a lower surface side of said orbiting scroll by performing said orbital motion relative to said first and second fixed scroll; and ports that allow said working fluid to enter or leave, disposed on said first base plate and said second base plate, said ports comprising first ports having openings in a vicinity of a winding start end portion of each of said first spiral tooth and said second spiral tooth, and second ports having openings near an inward facing surface of each of said first spiral tooth and said second spiral tooth at a position that is separated from said winding start end portion of each of said first spiral tooth and said second spiral tooth by an involute angle of approximately 90 degrees.