Scroll fluid machine with oil injection part and oil relieving passage

Claim 1

A scroll fluid machine having a stationary scroll member and an orbiting scroll member each having an end plate and a substantially spiral wrap extending from a plane of said end plate, said end plate of said stationary scroll member having a suction port and a discharge port respectively formed in a peripheral and a central portion thereof, said stationary and orbiting scroll members being assembled together with their wraps meshing with each other so as to form enclosed spaces between said wraps, means for enabling said orbiting scroll member to effect an orbital movement with respect to said stationary scroll member without rotating about its own axis whereby the volumes of said enclosed spaces are progressively decreased and a gas is drawn in from said suction port and progressively compressed in said enclosed spaces until the gas is discharged through said discharge port, wherein the improvement comprises: at least one oil injection port formed in said stationary scroll member, and at least one oil relieving passage defined between both scroll members, said oil injection port opening into at least one of said enclosed spaces, a wrap space defined between both scroll members and in a course of forming said one of said enclosed spaces serving for said oil relieving passage for providing an intermittent communication between a suction chamber and said oil injection port, and wherein said oil injection port is positioned in accordance with the following relationship: λe-2π<λoin<λe-2π+π/4, wherein: λoin: position of oil injection port in terms of scroll wrap angle (rad) λe: position of wrapping terminal end of scroll wrap angle (rad) π: circumference of circle to diameter ratio.