Scroll-type fluid machine

Abstract

A scroll-type fluid machine includes a mechanism for driving a movable scroll relative to a fixed scroll. The mechanism includes a drive shaft rotatable on a first axis, an eccentric pin and a bearing. The eccentric pin revolves around the first axis with the rotation of the drive shaft and has an outer peripheral surface centered on a second axis that is parallel to and eccentric to the first axis. The bearing is mounted to the movable scroll and has an inner peripheral surface centered on a third axis that is parallel to and eccentric to the first and second axes. The inner peripheral surface is in contact with the outer peripheral surface of the eccentric pin. Pressing force is applied to the bearing from the eccentric pin due to the arrangement of the first, second and third axes so as to press the movable scroll to the fixed scroll.

1 . A scroll-type fluid machine, comprising:
 a fixed scroll and a movable scroll engaged with each other;   an anti-rotation mechanism for preventing the rotation of the movable scroll on its own axis; and   a drive mechanism for driving the movable scroll in orbital motion relative to the fixed scroll, the drive mechanism including:
 a drive shaft rotatable on a first axis; 
 an eccentric pin revolving around the first axis with the rotation of the drive shaft, the eccentric pin having an outer peripheral surface centered on a second axis that is parallel to and eccentric to the first axis; and 
 a bearing mounted to the movable scroll, the bearing having an inner peripheral surface centered on a third axis that is parallel to and eccentric to the first and second axes, the inner peripheral surface being in contact with the outer peripheral surface of the eccentric pin, 
 wherein pressing force is applied to the bearing from the eccentric pin due to the arrangement of the first, second and third axes so as to press the movable scroll to the fixed scroll. 
   
     
     
         2 . The scroll-type fluid machine according to  claim 1 , further comprising a counterweight having center of gravity on an extension of a straight line extending from the third axis to the first axis, the counterweight being formed integrally with the drive shaft and the eccentric pin. 
     
     
         3 . The scroll-type fluid machine according to  claim 1 , further comprising a counterweight having center of gravity on an extension of a straight line extending from the third axis to the first axis, wherein the eccentric pin and the counterweight are integrally mounted on the drive shaft. 
     
     
         4 . The scroll-type fluid machine according to  claim 2 , wherein the movable scroll is formed with a cylindrical boss centered on the third axis, and the bearing is provided by a roller bearing mounted in the boss. 
     
     
         5 . The scroll-type fluid machine according to  claim 1 , wherein rotational force for rotating the movable scroll and driving force directed in a direction from the third axis to the second axis are generated by the rotation of the drive shaft, and the pressing force is the vector difference between the rotational force and the driving force. 
     
     
         6 . The scroll-type fluid machine according to  claim 5 , wherein the scroll-type fluid machine is a compressor, and the rotational force serves to compress refrigerant gas. 
     
     
         7 . The scroll-type fluid machine according to  claim 1 , wherein the bearing includes an inner ring having an inner diameter that is larger than the outer diameter of the eccentric pin, the inner ring being in line contact with the outer peripheral surface of the eccentric pin.