Patent ID: 6862974

Claim:
A rotary fluid machine including a casing ( 7 ) having a rotor chamber, a rotor ( 31 ) rotatably accommodated in said rotor chamber ( 14 ), cylinders ( 39 ) mounted radially in said rotor ( 31 ), pistons ( 41 ) for sliding in said cylinders ( 39 ), rollers ( 59 ) for moving in operative association with said pistons ( 41 ), and non-circular annular grooves ( 60 ) provided in said casing ( 7 ) to guide said rollers ( 59 ), so that a pressure energy of a working fluid flowing into and out of said cylinders ( 39 ) and a mechanical energy for rotating said rotor ( 31 ) can be converted from one into another by converting the reciprocal movement of said pistons ( 41 ) and the rotational movement of said rotor ( 31 ) from one into another by the engagement of said rollers ( 59 ) and said annular grooves ( 60 ) with each other, wherein a value in a positive peak region of a pressure load of the pistons ( 41 ) received by said rollers ( 59 ) and a value of a positive peak region of a centrifugal force load received by said rollers ( 59 ) are set, so that said values are substantially equal to each other, and phases of said two peak regions are deviated from each other, whereby a peak value of a resultant force of the pressure load and the centrifugal force load of the pistons ( 41 ) received by said rollers ( 59 ) and an amount of variation in each of the loads are suppressed to a small level.