Scroll type compressor with spiral oil feeding grooves in thrust bearing

A scroll type compressor which comprises in combination:

• (a) a stationary scroll and an orbiting scroll, each of which is constructed with a base plate and a wrap plate in a spiral form projectively provided on the surface of said base plate, both said scrolls defining a compression chamber by being mutually combined in an offset relationship;
• (b) a main shaft which holds a shaft for said orbiting scroll provided at a side opposite to the wrap plate of said orbiting scroll by offsetting said shaft for said orbiting scroll for a predetermined quantity to cause said orbiting scroll to perform the orbiting motion, said main shaft being rotatably received in a main bearing;
• (c) a thrust bearing which holds the surface of said base plate of said orbiting scroll at the side opposite to the surface where said wrap plate is provided, said thrust bearing having a center point O and a center opening for receipt of said shaft for said orbiting scroll;
• (d) a bearing support means in which said main bearing and said thrust bearing are provided;
• (e) a rotation-preventing mechanism which:
• (i) prevents said orbiting scroll from rotating on and around its axis and
• (ii) causes the same to revolve around said main bearing;
• (f) an oil path which:
• (i) is bored in and through said main shaft to define an oil-feeding port;
• (ii) is open to an oil sump where the bottom end of said main shaft is immersed;
• and
• (iii) feeds lubricating oil to said main bearing and said thrust bearing;
• and
• (g) a plurality of oil feeding grooves formed in the surface part of said thrust bearing in point symmetry with respect to the center point O of said thrust bearing, said oil feeding grooves being in the form of involute curves projecting from the center point O of said thrust bearing.