Multi-section roots vacuum pump of reverse flow cooling type.

摘要

A multi-section Roots vacuum pump of the reverse-flow cooling type having a plurality of pump sections each having rotors fixed to two common shafts. The pump includes a housing (11) in each of the pump sections having an inlet (13) and an outlet (14) for a gas to be pumped and enclosing the rotors, a peripheral gas passages (16A, 16B) arranged around the housing, and a peripheral coolant water passages (9) arranged around the peripheral gas passages. The gas flowing through the inlet into the housing and delivered through the outlet is supplied to the peripheral gas passages to be cooled there, and at least a portion of the cooled gas is returned into the housing. The remaining portions of the gas which are not returned into the housing in the pump sections except for the last pump section are supplied to the inlet of the next pump section through the peripheral gas passage.