Patent ID: 7491042

Claim:
A multistage compression type rotary compressor comprising, in a sealed vessel, a driving element; and first and second rotary compression elements driven by the driving element, the second rotary compression element comprising a cylinder; a roller fitted into an eccentric portion formed on a rotary shaft of the driving element to eccentrically rotate in the cylinder; and a vane which abuts on the roller to divide the inside of the cylinder into a low pressure chamber side and a high pressure chamber side, the rotary compressor being configured to suck, in the second rotary compression element, an intermediate pressure refrigerant gas compressed by the first rotary compression element and discharged, compress and discharge the refrigerant gas into the sealed vessel and apply a high pressure as a back pressure of the vane, the rotary compressor further comprising: a communication path which connects a region having an intermediate pressure to a region having a low pressure as a suction pressure of the first rotary compression element; and a valve device which opens or closes the communication path, the valve device being configured to open the communication path in a case where a pressure difference between the intermediate pressure and the low pressure increases to a predetermined upper limit value before the intermediate pressure reaches the high pressure.