Patent ID: 7377755

Claim:
A multi-stage rotary compressor comprising first and second compressing units mounted in a hermetic casing to compress a gas, the gas being primarily compressed in the first compressing unit and secondarily compressed in the second compressing unit, wherein the interior of the hermetic casing is divided into a plurality of spaces including first and second pressure chambers, the first pressure chamber surrounding the first compressing unit and being kept at a discharge pressure of the first compressing unit, the second pressure chamber surrounding the second compressing unit and being kept at a discharge pressure of the second compressing unit, the first compressing unit includes a first cylinder body defining a first compression chamber, a first roller that eccentrically rotates in the first compression chamber to compress the gas, and a first vane that reciprocates in a radial direction of the first compression chamber according to a rotation of the first roller to divide the interior of the first compression chamber into a suction space and a discharge space, the second compressing unit includes a second cylinder body defining a second compression chamber, a second roller that eccentrically rotates in the second compression chamber to compress the gas, and a second vane that reciprocates in a radial direction of the second compression chamber according to a rotation of the second roller to divide the interior of the second compression chamber into a suction space and a discharge space, and the compressor further comprises: a first partition interposed between the first cylinder body and the second cylinder body in order to separate the first and second compression chambers from each other and to divide the interior of the hermetic casing into the first and second pressure chambers, a second partition disposed under the first compressing unit in order to divide the interior of the hermetic casing into the first pressure chamber and an oil sump under the first pressure chamber, wherein the oil sump communicates with the second pressure chamber via a channel to keep the same pressure as that of the second pressure chamber.