Scroll compressor having improved orbital drive mechanism

Abstract

A scroll compressor includes an orbital drive mechanism for causing orbiting of an orbiting scroll relative to a stationary scroll. The orbiting scroll is formed with a generally cylindrical boss extending in a direction away from the stationary scroll. The orbital drive mechanism includes a main shaft rotatably supported by a compressor housing, an eccentric shaft extending from one end face of the main shaft and having a longitudinal axis parallel to, but offset laterally from a longitudinal axis of the main shaft, and an eccentric bush having a socket inserted rotatably into the cylindrical boss. The eccentric shaft, engaged in the socket, is of a non-circular cross-section having short and long axes perpendicular to each other. The eccentric shaft has rounded opposite apexes lying on the long axis thereof to define first and second rounded side faces, while the socket has a first inner wall portion of a smaller curvature confronting the first rounded side face of the eccentric shaft and a second inner wall portion of a greater curvature confronting the second rounded side face of the eccentric shaft. The eccentric shaft is spaced a predetermined distance from inner wall portions of the socket in the direction in which the short axis of the eccentric shaft extends so that the eccentric bush can swing relative to the eccentric shaft about a center of curvature of the first rounded side face of the eccentric shaft, thus varying the orbiting radius.