Scroll fluid apparatus with axial sealing force

Claim 1

A scroll fluid apparatus comprising: scroll means including a revolving scroll member and a stationary scroll member, each of said revolving scroll member and said stationary scroll member having an end plate and a wrap extending from said end plate and disposed in an upright position; drive shaft means mounted for rotation about its center axis which is eccentric with respect to the center of said revolving scroll member so as to cause the revolving scroll member to revolve around said drive shaft means; housing means formed therein with a housing chamber; an Oldham's ring for preventing the revolving scroll member from revolving about its center and causing the same to revolve around said drive shaft means without changing its posture; a suction port; and an outlet port; wherein the improvement comprises: a mechanical seal mounted in a portion of said housing means through which said drive shaft means extends so as to provide a seal to said housing chamber; and at least one small aperture formed in the end plate of one of said two scroll members for communicating said housing chamber with operating chambers of the scroll fluid apparatus in the process of compressing or expanding a fluid so as to keep the internal pressure of said housing chamber at a pressure level which is intermediate between the pressure at which the fluid is sucked into said operating chambers and the pressure at which the fluid is discharged therefrom, so that the fluid at the intermediate pressure level can force one scroll member tightly against the other scroll member to provide an axial seal thereto.