Scroll type fluid machine

摘要

In a low speed rotation, side surfaces of a spiral wrap (2b) of a swivel scroll (2) are brought into pressing contact with side surfaces of a spiral wrap (1b) of a stationary scroll (1) to thereby keep an air tight condition therebetween. When the orbiting swivelling speed of the swivel scroll exceeds the predetermined level, a predetermined gap is kept between the side surfaces of the spiral wrap (2b) of the swivel scroll and the side surfaces of the spiral wrap (1b) of the stationary scroll to thereby prevent the abnormal wear of the spiral wraps and to thereby suppress the increase of the consumption power. A counterweight (10) is provided to a drive bush (5) for generating a centrifugal force Fc which is greater than a centrifugal force Fs applied to the swivel scroll (2) during the orbiting swivelling motion of the swivel scroll and which is directed in an opposite direction to that of the centrifugal force Fs. A spring member (15) is provided for biasing the drive bush (5) in a direction in which the orbiting swivelling radius is increased in a slide direction theta . Thus, the swivel scroll (2) is shifted in a direction in which the orbiting swivelling radius is decreased when the orbiting swivelling speed exceeds the predetermined level.