Scroll compressor having optimized oil passages

Abstract

A scroll compressor comprises a generally cylindrical casing and stationary and orbiting scrolls both accommodated in the casing. The stationary and orbiting scrolls engage with each other to define a plurality of compression chambers therebetween. The orbiting scroll is driven by a drive shaft which is in turn supported by a frame having a thrust bearing formed thereon. One of an orbiting end plate of the orbiting scroll and the thrust bearing has an annular groove defined therein in which an annular seal member is received. The orbiting scroll is disposed between the stationary scroll and the frame with an axial gap defined therebetween. First, second, and third back chambers are formed on the opposite side of the compression chambers with respect to the orbiting end plate. The first and second back chambers are partitioned by the annular seal member. The second back chamber is provided radially outwardly of the first back chamber and between the orbiting end plate and the thrust bearing, while the third back chamber is provided radially outwardly of the second back chamber. Oil passages are provided to introduce lubricating oil accommodated in the casing into the first chamber in which a discharge pressure acts. The oil passages act to supply part of the lubricating oil to the second chamber and then to the third chamber while reducing the pressure of the lubricating oil until the lubricating oil is eventually introduced into the suction chamber.