US Patent 7223082 Rotary compressor

A so-called internal intermediate pressure multistage compression type rotary compressor makes it possible to prevent the pressure inside a roller from inconveniently increasing and also to permit smooth and reliable supply of oil into a cylinder of a second rotary compressing element by a relatively simple construction. A lubrication groove for providing communication between an oil bore and a low-pressure chamber in the cylinder is formed in a surface of an intermediate partitioner that is adjacent to the cylinder of the second rotary compressing element. Furthermore, a through bore for providing communication between a hermetically sealed vessel and the inside of the roller is formed in the intermediate partitioner.