Patent ID: 7950911
Filing Date: 2011-05-31
Classification: F01C,F04C

Abstract:
1. A single stage root type-vacuum pump configured to perform normal rotation and reverse rotation, comprising: a casing having a suction port and a discharge port spaced apart from the suction port; a pair of three-lobe rotors located inside the casing and each having three lobes, the casing and the three-lobe rotors being configured to suck a fluid from the suction port and to discharge the fluid from the discharge port by a rotation of the pair of three-lobe rotors while avoiding communication between the suction port and the discharge port, wherein: a check valve having an outside air introduction pipe connected to an outside air communication hole provided on a casing lid on the discharge port side of the casing, the check valve being configured to prevent fluid from flowing out of the casing during reverse rotation of the rotors.