Vacuum pump system including scroll pump and secondary pumping mechanism

A vacuum pumping system comprising the combination of a scroll pump 100 and a secondary pumping mechanism 200. The stationary portion 110 of the scroll pump includes the stationary scroll plate 160 and defines and additional gas passageway 190. The vacuum pump has a check valve 140 disposed in its exhaust opening. The secondary pumping mechanism is operatively associated with the additional passageway to draw residual gas in the compression stage upstream of the check valve into the passageway to evacuate residual gas from the compression stage. The secondary pumping mechanism may comprise a piston 210 disposed in the additional passageway, which may be thermally or magnetically actuated 220. The secondary pump may provide a hermetic seal in the additional passageway between the compression stage and the atmosphere outside the pump. In another embodiment the secondary pumping mechanism is reciprocating such that the gas drawn into the additional passage way on the intake stroke can be forced ...