Scroll type compressor with displacement adjusting mechanism

Claim 1

In a scroll type compressor including a pair of scrolls each having an end plate and a wrap extending from one side surface of said end plate, said wraps interfitting at an angular and radial offset to make a plurality of line contacts between said wraps to define at least one pair of sealed off fluid pockets, and a driving mechanism operatively connected to one of said scrolls for orbiting said one scroll relative to the other one of said scrolls while preventing rotation of said one scroll to thereby change the volume of the fluid pockets, the improvement comprising: one end plate having at least two pairs of holes in fluid communication with a suction chamber, said holes of each pair of holes being located at symmetrical locations along the wrap which extends from said one end plate so that said other wrap simultaneously crosses over both of said holes in each pair of holes, the most inwardly placed hole of said pairs of holes being located within an area defined by φend-2(n-1)π>φ1>φend-2nπ, where φend is the final involute angle of said wrap which extends from said one end plate, φ1 is the involute angle at which said most inwardly placed hole is located and n is the number of pairs of holes, the most outwardly placed hole of said pairs of holes being located within an area defined by φ(n-1)+2π>φn>φend-2π, and the intermediate holes of said pairs of holes being located within an area defined by φ(k-1)+2π>φk>φ(k+1)- 2π, where φk is the involute angle at which the kth hole from the most inwardly placed hole is located; and control means for selectively opening and closed said pairs of holes to permit fluid communication therethrough to said suction chamber to thereby selectively control the displacement volume of said compressor.