Patent ID: 7455508

Claim:
A scroll type fluid machine including a casing, a fixed scroll provided on said casing and having an end plate and a spiral wrap portion extending from said end plate, and an orbiting scroll opposed to said fixed scroll within said casing and having an end plate and a spiral wrap portion extending from said end plate, said wrap portion of said orbiting scroll overlapping said wrap portion of said fixed scroll, said scroll type fluid machine comprising; a rotary shaft which has one end attachable to an output shaft of a rotating drive source and a sub weight which is protruded radially from said one end of said rotary shaft; a main bearing adapted to rotatably support said rotary shaft and having an outer periphery which is attached to said casing and an inner periphery into which the other end of said rotary shaft is inserted from a rotating drive source side of said main bearing; a driving bush which is non-rotatably attached to said other end of said rotary shaft from an orbiting scroll side of said main bearing and to which said orbiting scroll is attached via an orbit bearing at a position eccentric radially from an axis of said rotary shaft; and a counter weight provided on said driving bush; wherin said sub weight is protruded from said rotary shaft in the same direction as an eccentric direction of said orbiting scroll, a dimension of a portion of said sub weight protruded from said rotary shaft is larger than an inner diameter of said main bearing, and said sub weight has a center of gravity located at a position eccentric radially from an axis of said rotary shaft in the protruded direction of said sub weight; and wherin said counter weight has a center of gravity located at a position eccentric radially from said axis of said rotary shaft in a direction opposite to the eccentric direction of said orbiting scroll.