Patent ID: 6149405
Filing Date: 2000-11-21
Classification: F04C

Abstract:
A double-wrap dry scroll vacuum pump having a pump body comprising:a revolving scroll including a base and a pair of revolving scroll wraps arranged on both sides of the base, a pair of stationary scrolls each having a scroll wrap engaged with each revolving scroll wrap and holding the revolving scroll on both sides, and a drive shaft penetrating a central part of each of the stationary scrolls, a central part of the revolving scroll being driven by the drive shaft;the pump body further comprising;a suction port;a discharge port for discharging compressed gas compressed by means of progressive volume reduction of sealed spaces formed by the revolving and stationary scrolls, to the outside of the pump body;a pair of enclosing members each mounted to an external surface of one of the stationary scrolls via a sealing member and each of the enclosing members covering an end portion of the drive shaft, each of the end portions of the drive shaft being in fluid communication with one of a pair of compressed gas feed ports each located in one of the enclosing members;a compressed gas axial cooling passage formed in the drive shaft and a compressed gas being introduced to each end portion of the drive shaft and into the axial cooling passage from each of the compressed gas feed ports, and the drive shaft further including at least one additional passage in fluid communication with the axial cooling passage for introducing the compressed gas to a bearing which supports the drive shaft; anda gas bearing in fluid communication with the axial cooling passage through a discharge passage in the drive shaft, the gas bearing operable to rotatable support the drive shaft by use of the compressed gas supplied from the compressed gas feed ports.