摘要:
A movable race 25 fixed to a movable scroll 20 which revolves with respect to a fixed scroll and a fixed race 24 opposing the movable race are respectively provided with pluralities of annular ball rolling grooves 24c and 25c extending along the revolutionary locus of the movable scroll and a plurality of balls 26 are held sandwiched between the plurality of ball rolling grooves of the movable race and the plurality of ball rolling grooves of the fixed race. Further, the radius of revolution S1 to be obtained by the movable race, the plurality of balls, and the fixed race is made smaller than the radius of revolution S2 to be determined by the scroll wall of the movable race and that of the fixed race.