Scroll type compressor with displacement adjusting mechanism

Claim 1

In a scroll type fluid compressor including a housing having a fluid inlet port and a fluid outlet port, a fixed scroll fixedly disposed within said housing and having a circular end plate from which a first wrap extends into the interior of said housing, an orbiting scroll having a circular end plate from which a second wrap extends, said first and second wraps interfitting at angular and radial offsets to form a plurality of line contacts to define at least one pair of sealed off fluid pockets, a driving mechanism operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll by rotation of a drive shaft and rotation preventing means for preventing the rotation of said orbiting scroll during orbital motion to thereby change the volume of the fluid pockets, the improvement comprising: said end plate of said fixed scroll partitioning the interior of said housing into a first chamber in which said first wrap extends and a second chamber; a partition wall disposed within said second chamber to provide an outer peripheral chamber and a central chamber; at least one pair of holes formed through said end plate of said fixed scroll to form a fluid communication channel between the pair of fluid pockets and said outer peripheral chamber, said pair of holes being located at symmetrical locations along said first wrap so that said second wrap simultaneously crosses over both of said pair of holes, a first of said pair of holes being located within an area defined by φend>φ1>φend-2π where φ end is the final infolute angle of said first wrap and φ1 is the involute angle at which said first hole is located, the other of said holes being located at an involute angle of approximately 100 1-π; a valve member associated with each hole to selectively control the opening and closing of said pair of holes; a communicating hole formed through said end plate of said fixed scroll to form a fluid communication channel between said first chamber and said outer peripheral chamber, said communicating hole being located at the outside of a terminal end of said first wrap; and control means for selectively controlling the opening and closing of said communicating hole to permit fluid communication therethrough.