Scroll type compressor with displacement adjusting mechanism

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 end 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 an angular and radial offset to form a plurality of line contacts which 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, rotation preventing means for preventing the rotation of said orbiting scroll during orbital motion to thereby change the volume of the fluid pockets and a discharge chamber associated with said fluid outlet port and located adjacent one of said circular end plates on a side opposite its respective wrap to receive compressed fluid from a central fluid pocket formed by said scrolls during orbital motion, the improvement comprising:

• at least one pair of holes formed through said circular end plate of one of said scrolls to form a fluid channel between the pair of sealed off fluid pockets and an intermediate pressure chamber located on the opposite side of said circular end plate of said one scroll from its respective wrap and separated from said discharge chamber, said pair of holes being located at symmetrical locations along said respective wrap so the wrap of the other of said scrolls simultaneously crosses over both of said pair of holes during orbital motion of said orbiting scroll, a communication channel formed through said circular end plate of said one scroll and opening onto a suction passageway which forms a fluid channel between said intermediate pressure chamber and a suction chamber located on the same side of said circular end plate of said one scroll as its respective wrap, said suction passageway also formed between said inlet port and said suction chamber, first control means for selectively controlling the opening and closing of said communication channel between said intermediate pressure chamber and said suction chamber, and second control means operating in conjunction with the operation of said first control means for increasing the resistance of said scroll type fluid compressor to suction during the initial opening of said communication channel by said first control means to thereby adjust the compression ratio of said scroll type fluid compressor.