Patent ID: 7585162

Claim:
A compression system comprising: a multicylinder rotary compressor in which a sealed container stores a driving element and first and second rotary compression elements driven by a rotation shaft of the driving element, the first and second rotary compression elements comprising: first and second cylinders; first and second rollers which are fitted into eccentric portions formed in the rotation shaft and which eccentrically rotate in the respective cylinders; and first and second vanes which abut on the first and second rollers to partition the inside of each cylinder into low and high-pressure chamber sides, only the first vane being urged toward the first roller by a spring member, the compressor having a first operation mode in which both the rotary compression elements perform a compression work and a second operation mode in which only the first rotary compression element substantially performs the compression work, the system further comprising: a valve device for controlling circulation of a refrigerant into the second cylinder, wherein in the first operation mode an intermediate pressure, which is between suction-side pressure and discharge-side pressure of both the rotary compression elements, is applied as a back pressure of the second vane; wherein in the second operation mode the suction-side pressure is applied as the back pressure of the second vane; and wherein when switching from the first operation mode to the second operation mode the valve device interrupts flowing of the refrigerant into the second cylinder, and thereafter the suction-side pressures of both the rotary compression elements are applied as the back pressure of the second vane.