Scroll compressor having changeable axis in eccentric drive

Claim 1

A scroll compressor comprising: a stationary scroll member including a stationary end plate and a stationary spiral wrap extending from the stationary end plate; an orbiting scroll member including an orbiting end plate and an orbiting spiral wrap extending from the orbiting end plate and which orbits around the axis of the stationary scroll member and has an orbiting bearing, the wraps of the stationary scroll member and the orbiting scroll member engaging with each other to form a fluid compressing chamber; an anti-rotating device for preventing the orbiting scroll member from rotating on its own axis and for permitting the orbiting scroll member to orbit around the axis of the stationary scroll member; a main shaft rotatable on its own axis and including a pivot pin having an axis spaced from the axis of the main shaft; an eccentric drive shaft having an axis spaced from the axis of the main shaft and orbital around the axis of the main shaft, said eccentric drive shaft being rotationally engageable with the orbiting bearing so as to enable the eccentric drive shaft to drive the orbiting scroll member around he axis of the stationary scroll member, said eccentric drive shaft including a pivot bearing having an axis spaced from the axis of the eccentric drive shaft and rotationally engageable with the pivot pin so that the eccentric drive shaft orbits around the axis of the pivot pin, a distance between the axis of the eccentric drive shaft and the axis of the main shaft is adapted to be changed, and the main shaft drives the eccentric drive shaft to orbit around the axis of the main shaft; a balance weight connected to the eccentric drive shaft, wherein a center of gravity of the balance weight is spaced from the axis of the main shaft, a direction of rotational moment generated on the axis of the pivot pin by a compressed gas force transmitted from the compressing chamber to the eccentric drive shaft is opposite to a direction of rotational moment generated by the centrifugal force of the balance weight on the axis of the pivot pin, the rotational moment generated by the compressed gas pushes the eccentric drive shaft away from the main shaft and pushes the eccentric drive shaft away from the pivot pin in a direction perpendicular to a direction of force applied to the axis of the eccentric derived shaft by the compressed gas, the rotational moment generated by the centrifugal force of the balance weight draws the eccentric drive shaft toward the main shaft; and limiting means for limiting a range of orbital motion of the eccentric drive shaft around the axis of the pivot pin, a distance between the limiting means and the axis of the main shaft is larger in a direction of a line extending betweent the axis of the main shaft and the axis of the eccentric drive shaft than a distance between the axis of the main shaft and the axis of the pivot pin.