Scroll pump with overpressure exhaust

摘要

The present invention relates to a scroll pump with two scrolls that are co-operable for pumping fluid from an inlet to an outlet on relative orbiting motion of the scrolls. Each scroll comprises a scroll base from which a scroll wall extends generally axially towards the base of the opposing scroll. A gas conduit having an inlet at a first location of the pumping channel and an outlet at a second location of the pumping channel allows over-compression at the first location of the pumping channel to be exhausted to the second location of the pumping channel. A one-way valve located in the gas conduit allows the passage of gas through the conduit from the conduit inlet to the conduit outlet when a predetermined pressure differential between the first and second locations of the pumping channel is generated during roughing when the scroll inlet is at or close to atmosphere.

主权项

1. A vacuum pump comprising a scroll pumping mechanism which comprises:
two scrolls which are co-operable for pumping gas along a pumping channel from a scroll inlet to a scroll outlet of the mechanism on relative orbiting motion of the scrolls, a gas conduit having an inlet at a first location of the pumping channel and an outlet at a second location of the pumping channel for allowing over-compression of gas above atmosphere at the first location of the pumping channel to be exhausted to the second location of the pumping channel, and a one-way valve arrangement located in the gas conduit for allowing the passage of gas through the conduit from the conduit inlet to the conduit outlet only when a predetermined pressure differential between the first and second locations of the pumping channel is generated during roughing when the scroll inlet is at or close to atmosphere; wherein the scroll pumping mechanism further comprises a first section adjacent the scroll inlet and a second section adjacent the scroll outlet and the pumping capacity of the first section is larger than the pumping capacity of the second section and the first section has a deeper pumping channel than the second section, and wherein the inlet of the gas conduit is downstream of a transition between the first section and the second section.