Scroll type compressor with variable displacement mechanism

Claim 1

In a scroll type compressor including a housing having an inlet port and an outlet port, a fixed scroll fixedly disposed within said housing and having a circular end plate from which a first spiral element extends into the interior of said housing, an orbiting scroll having a circular end plate from which a second spiral element extends, said first and second spiral elements interfitting at an angular and radial offset to make a plurality of line contacts and define at least one pair of fluid pockets within the interior of said housing, a driving mechanism operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll, a rotation preventing mechanism for preventing the rotation of said orbiting scroll during the orbital motion, said circular end plate of said fixed scroll dividing the interior of said housing into a front chamber and a rear chamber, said front chamber communicating with said inlet port, and said rear chamber being divided into a discharge chamber which communicates between said outlet port and a central fluid pocket formed by both said scrolls and an intermediate pressure chamber, the improvement comprising: at least one pair of holes formed through said circular end plate of said fixed scroll forming a fluid channel between the fluid pockets and said intermediate pressure chamber, a communication channel formed through said circular end plate of said fixed scroll to form a fluid channel between said intermediate pressure chamber and said front chamber, control means disposed on a portion of said intermediate pressure chamber for controlling fluid communication between said intermediate pressure chamber and said front chamber, said control means comprising a valve element operated by the compressed fluid in said discharge chamber, and a cylinder, a piston slidably disposed within said cylinder, and a control valve element, a top portion of said cylinder being connected to said discharge chamber, said control valve element controlling the communication between said discharge chamber and said front chamber.