Double wrap dry scroll vacuum pump having a compressed gas cooling passage disposed in the scroll shaft

摘要

A double-wrap dry scroll vacuum pump for use as a vacuum pump for nuclear power equipment. The pump has a pump body including a suction port capable of being communicated with a vessel to be evacuated and a discharge port for discharging wrap compressed gas to an outside of the pump body after an operation of gas compression by the progressive volume reduction of a sealed space, formed by a revolving scroll and a pair of stationary scrolls. The pump further includes a pair of enclosing members which cover opposite end portions of a drive shaft and are mounted in a gas-tight state around the revolving scroll. The pump has compressed gas feed ports for feeding compressed gas therethrough to the enclosing members, the compressed gas having a higher pressure than the wrap compressed gas and is discharged together with the wrap compressed gas through the discharge port. To attain high performance and durability, the double-wrap dry scroll vacuum pump has a gas bearing in fluid communication with the compressed gas feed ports to rotatably support the drive shaft. A contact-less torque transmission means is implemented for transmitting torque from a driving source to the drive shaft.