Edwards Limited

Philip John Stephens

Ian David Stones

Malcolm William Gray

Paul David Neller

Michael Geoffrey Thompson

A method and apparatus for reducing undesirable noise generated by a vacuum pumping system. The vacuum system operates to reduce the pressure in a chamber to a first pressure value. The system then detects that the pressure at the vacuum pump system's inlet is about to change to a second higher pressure and, in response, the speed of a booster pump in the vacuum pump system is reduced below the rated speed for the pump. When the pressure at the vacuum pump's inlet is above the second pressure, the speed of the booster pump is increased to the rated speed. Thus, the booster pump is slowed down prior the pump system becoming exposed to a rapid increase in inlet pressure.

Evacuating a chamber

A pump includes a plurality of pumping stages comprising a respective plurality of pumping mechanisms driven by one or more drive shafts for pumping fluid through the pumping stages from a pump inlet at a high vacuum stage to a pump outlet at a low vacuum stage; a lubrication chamber housing a bearing assembly for supporting the drive shaft for rotational movement, the drive shaft extending from the high vacuum stage to the lubrication chamber through an opening of a head plate of the lubrication chamber; an inter-stage purge port through which gas can enter the pump at an inter-stage location downstream of the high vacuum; a lubrication chamber purge port located in the lubrication chamber through which purge gas can flow from a source of purge gas; wherein the inter-stage port is connected to the lubrication chamber for controlling the pressure of purge gas in the lubrication chamber.

Pump

Vacuum pump for pumping gas from a process chamber, the pump comprising: a rotor supported for rotation in a pumping chamber by a drive shaft, the shaft extending through a shaft bore in a wall of the pumping chamber extending transversely to the drive shaft, and a seal arrangement provided between the shaft and the transverse wall for resisting the passage of gas through the shaft bore, wherein on rotation of the rotor gas is pumped from a low pressure region at an inlet of the pumping chamber to a high pressure region at an outlet of the pumping chamber, and wherein the rotor and the transverse wall are spaced apart by an axial clearance along which back leakage of gas can flow from the high pressure region to the low pressure region, and an additional leakage path for back leakage is formed spaced away from the seal arrangement along which gas can flow without contact with the seal arrangement so that the amount of gas which contacts the seal arrangement during use of the pump is reduced.

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Worthing, United Kingdom

Philip John Stephens