Patent ID: 7976289
Filing Date: 2011-07-12
Classification: F04C

Abstract:
1. A capacity variable type rotary compressor, comprising: a casing having a gas suction pipe configured to be connected to an evaporator and a gas discharge pipe configured to be connected to a condenser; a cylinder fixed in the casing, the cylinder having an inner space formed at a center thereof for compressing a refrigerant as a rolling piston performs an orbit motion, and having an inlet penetratingly formed at the inner space in a radial direction so as to be connected to the gas suction pipe, and having a vane slit formed in a radial direction so as to support a vane therein that divides the inner space into a compression chamber and a suction chamber by contacting the rolling piston in a radial direction; a plurality of bearing plates for covering upper and lower sides of the cylinder and thereby sealing the inner space, a first of the plurality of bearing plates having a discharge port provided with a discharge valve connected to the inner space of the cylinder for discharging a compressed refrigerant, and a second of the plurality of bearing plates having a plurality of bypass holes formed therein that connect the compression chamber and the suction chamber of the cylinder divided from each other by the vane; a capacity varying unit coupled to the second of the plurality of bearing plates for selectively connecting the plurality of bypass holes and thereby bypassing a part of a compressed refrigerant to the inlet of the compressor; a back pressure switching unit that selectively supplies a different back pressure to the capacity varying unit so that the capacity varying unit can open or close the plurality of bypass holes according to a driving mode of the compressor; and a pressure difference maintaining unit that forcibly controls a refrigerant flow so that an opened state or a closed state of the capacity varying unit can be maintained for a certain time, wherein the back pressure switching unit comprises: wherein the switching valve assembly comprises: wherein the pressure difference maintaining unit comprises: a second refrigerant flow controller installed between an inlet of the evaporator and an outlet of the condenser, the second refrigerant flow controller forming a high pressure by opening a second refrigerant pipe between the evaporator and the condenser when the compressor is operated and the plurality of bypass holes are closed, and forming a low pressure by closing the second refrigerant pipe when the plurality of bypass holes are opened, the second refrigerant flow controller comprising: