Scroll type compressor with variable displacement mechanism

Abstract

A variable displacement type compressor is disclosed. The compressor includes a housing having fluid inlet and fluid outlet ports. A fixed scroll is disposed within the housing and has a circular end plate from which a first spiral element extends. The end plate of the fixed scroll partitions the inner chamber of the compressor housing into a front chamber connected to the fluid inlet port and a rear chamber. The rear chamber is divided into a discharge chamber connected to the fluid outlet port and an intermediate pressure chamber. The end plate of the fixed scroll has at least two holes which connect the fluid pockets to the intermediate pressure chamber. The end plate also has a communicating channel which connects the front chamber to the intermediate chamber. A control device controls the communication between the front chamber and intermediate pressure chamber. The control device is disposed on the intermediate pressure chamber and comprises first and second valve elements. The first valve element of the control device is operated by pressure from the discharge chamber. Pressure from the discharge chamber is controlled by the second valve element. The first valve element includes a cylinder and a piston slidably disposed within the cylinder. The cylinder has first and second openings. The first opening is formed at the intermediate pressure chamber side. The second opening is formed at the communicating channel side. A bottom end of the piston closes the second opening, when a top end of the piston receives discharge gas pressure.