Scroll-type compressor having injection passage part to establish communication between an external injection pipe and compression chamber, and relief mechanism to establish communication between compression chamber and back pressure chamber

Abstract

A scroll-type compressor includes a compression-chamber-forming member, a housing, an injection passage part, and a relief mechanism. The compression-chamber-forming member forms a compression chamber and has a movable scroll and a fixed scroll. The housing forms a back pressure chamber. Refrigerant to apply back pressure to the compression-chamber-forming member is accumulated in the back pressure chamber. The injection passage part is linked to the compression chamber. The relief mechanism is configured to establish a communication between the compression chamber and the back pressure chamber communicating when injection pressure of the refrigerant flowing from the injection passage part into the compression chamber is higher than the pressure in the back pressure chamber.