Patent ID: 8328545

Claim:
A scroll fluid machine comprising: a fixed-side member comprising a cylindrical casing and a fixed scroll fixed to the casing and having a spiral wrap portion erected on an end plate thereof; an orbiting scroll provided in the casing for orbit so as to face the fixed scroll of the fixed-side member and having a spiral wrap portion erected on an end plate thereof; a plurality of fluid chambers defined between the orbiting scroll and the fixed scroll to compress or expand a fluid between said wrap portions when the orbiting scroll orbits; and a plurality of ball coupling devices provided between said fixed-side member and said orbiting scroll to prevent self-rotation of the orbiting scroll on its axis and receive a thrust load between the fixed-side member and the orbiting scroll, wherein each of the ball coupling devices comprises: a first ball coupling mechanism for supporting the thrust load generated between the fixed-side member and the orbiting scroll by using a load supporting ball; and a second ball coupling mechanism disposed with a space from the first ball coupling mechanism to prevent the self-rotation of the orbiting scroll by using a self-rotation preventing ball, said second ball coupling mechanism comprising an elastic member for elastically supporting the self-rotation preventing ball in a radial direction of the orbiting scroll so as to suppress the effect of the backlash to the self-rotation direction that can affect said first ball coupling mechanism.