VACUUM PUMPING SYSTEM AND METHOD OF OPERATING VACUUM PUMPING SYSTEM

摘要

Pairs of rotors (R₁, R₂, R₃, R₄, R₅ and R₆) driven rotationally by a motor ( 22 ) are disposed in the body ( 21 ) of a main pump ( 20 ) comprising a multistage Roots dry vacuum pump. A suction opening ( 23 ) communicating with the rotor chamber of the rotor R₁ is provided in the upper wall portion at the left end of the body ( 21 ). A delivery section ( 24 ) communicating with the delivery side of the rotor chamber of rotor R₆ on the final stage is coupled to an exhaust pipe ( 25 ) and is provided with a silencer ( 26 ) and further coupled to a check valve ( 28 ) through a pipe ( 27 ). The check valve ( 28 ) has its forward direction toward the atmospheric side. The delivery section ( 24 ), or a delivery section ( 24 ') at the side intermediate stage, is coupled to an auxiliary pump ( 30 ) having an exhaust capacity smaller than that of the main pump ( 20 ). When the motor ( 22 ) is driven, gas exhausted through rotation of the rotors (R₁-R₆) is carried sequentially to the downstream side from the rotor chambers and a vacuum processing chamber coupled to the suction opening ( 23 ) is exhausted. The delivery section ( 24 ) on the final stage is exhausted by driving the auxiliary pump ( 30 ), and the pressure is reduced. Consequently, the burden of the exhaust action on the rotor (R₆) on the final stage or the rotor (R₅) on the intermediate stage is lessened, and the power consumption of the motor ( 22 ) can be reduced significantly as compared with the prior art.