Vacuum Pump

• US 20070274822A1
• Filed: 12/23/2004
• Published: 11/29/2007
• Est. Priority Date: 12/23/2003
• Status: Abandoned Application

• Current Assignee: Edwards Limited (Atlas Copco AB)
• Original Assignee: Edwards Limited (Atlas Copco AB)
• Inventors: Dowdeswell, Stephen, Liu, Michael, Schofield, Nigel
• Application Number:
  US10/581,934
• Publication Number:
  US 20070274822A1
• Time in Patent Office: Days
• US Class Current: 415/90
• CPC Class Codes: F04D 17/122 the individual rotor discs being, one for each stage, on a common shaft and axially spaced, e.g. conventional centrifugal multi- stage compressors
• CPC Class Codes: F04D 17/14 with means for changing the flow-path through the stages, e.g. series-parallel, e.g. side-loads, surge control F04D27/02
• CPC Class Codes: F04D 17/168 Pumps specially adapted to produce a vacuum
• CPC Class Codes: F04D 19/044 Holweck-type pumps
• CPC Class Codes: F04D 27/0207 by bleeding, bypassing or recycling fluids influencing the boundary layer by an uncontrolled bleeding of the working fluid F04D29/681
• CPC Class Codes: Y10T 137/86083 Vacuum pump

Abstract

A vacuum pumping arrangement is described for evacuating a load lock chamber. A booster pump comprises a molecular drag stage and a multi-stage centrifugal compressor mechanism. A backing pump comprises a multi-stage centrifugal compressor mechanism exhausting pumped fluid at atmospheric pressure. Such arrangements can reduce noise, size and vibration levels associated with conventional load lock pumping arrangements.

Claims

12. (canceled)

27. (canceled)

28. (canceled)

29. (canceled)

30. (canceled)

31. (canceled)

32. A vacuum pump comprising a multi-stage centrifugal compressor mechanism comprising a plurality of rotor elements mounted on a rotatably mounted drive shaft, and, upstream therefrom, a molecular drag mechanism comprising at least one rotor element mounted on the drive shaft, wherein the at least one rotor element of the molecular drag mechanism at least partially surrounds a motor for rotating the drive shaft.

33. The vacuum pump according to claim 32 wherein said at least one rotor element of the molecular drag pumping mechanism comprises a cylinder mounted for rotary movement with the rotor elements of the compressor mechanism.

34. The vacuum pump according to claim 32 comprising means for monitoring the temperature of the pump, and means for controlling the speed of rotation of the shaft in dependence on the monitored temperature.

35. (canceled)

36. (canceled)

37. A vacuum pumping arrangement comprising a vacuum pump in series with a backing pump, wherein the vacuum pump comprises a multi-stage centrifugal compressor mechanism comprising a plurality of rotor elements mounted on a rotatable mounted drive shaft, and, upstream therefrom, a molecular drag mechanism comprising at least one rotor element mounted on the drive shaft, wherein the at least one rotor element of the molecular drag mechanism at least partially surrounds a motor for rotating the drive shaft.

1. The vacuum pump arrangement according to claim 37 wherein the multi-stage centrifugal compressor mechanism comprises a housing within which the drive shaft is rotatably mounted, a plurality of fixed members disposed within the housing and defining a plurality of interconnected fluid chambers, the rotor elements of the compressor mechanism comprising a plurality of impellers mounted on the drive shaft and disposed relative to the fixed members such that each impeller delivers compressed fluid to a respective fluid chamber, the compressor mechanism further comprising a bypass channel extending between two of the fluid chambers to enable fluid to pass between those chambers without compression, and means for controlling the flow of fluid through the bypass channel.

2. The vacuum pump arrangement according to claim 1 wherein the control means is arranged to open the bypass channel under the influence of a pressure difference between said two of the fluid chambers.

3. The vacuum pump arrangement according to claim 1 wherein the control means is arranged to open the bypass channel when the pressure in an upstream one of said two of the fluid chambers is greater than the pressure in a downstream one of said two of the fluid chambers.

4. The vacuum pump arrangement according to claim 1 wherein said two of the fluid chambers are adjacent fluid chambers of the compressor mechanism.

5. The vacuum pump arrangement according to claim 4 wherein the bypass channel passes through the fixed member located between the adjacent fluid chambers.

6. The vacuum pump arrangement according to claim 1 wherein the control means comprises valve means.

7. The vacuum pump arrangement according to claim 6 wherein the valve means comprises a valve member displaceable in use between a closed position and an open position by pressurised fluid.

8. The vacuum pump arrangement according to claim 7 wherein the valve member comprises a flap valve.

9. The vacuum pump arrangement according to claim 6 wherein the valve means is located within a fluid chamber.

10. The vacuum pump arrangement according to claim 1 comprising, for each fluid chamber, a respective bypass channel extending between that fluid chamber and the adjacent downstream fluid chamber, and means for controlling the flow of fluid through each bypass channel.

11. The vacuum pump arrangement according to claim 1 further comprising surge control means for controlling surge within the multi-stage centrifugal compressor mechanism.

13. The vacuum pump arrangement according to claim 11 wherein the surge control means comprises means for conveying a stream of fluid to each fluid chamber, and means for controlling the rate of flow of the fluid stream into each fluid chamber.

14. The vacuum pump arrangement according to claim 13 wherein the conveying means is arranged to convey a stream of purge gas to each fluid chamber.

15. The vacuum pump arrangement according to claim 14 wherein the purge gas comprises air or an inert gas.

16. The vacuum pump arrangement according to claim 13 wherein the conveying means is arranged to convey a stream of compressed fluid to each fluid chamber from a downstream fluid chamber.

17. The vacuum pump arrangement according to claim 16 wherein the conveying means comprises, for each fluid chamber, a fluid passage extending between that fluid chamber and the adjacent downstream fluid chamber.

18. The vacuum pump arrangement according to claim 17 wherein the fluid passages are co-axial.

19. The vacuum pump arrangement according to claim 17 wherein each fluid passage passes through a respective fixed member.

20. The vacuum pump arrangement according to claim 16 wherein the control means comprises valve means in fluid communication with said conveying means.

21. The vacuum pump arrangement according to claim 20 wherein the valve means comprises a spool valve.

22. The vacuum pump arrangement according to claim 1 wherein each fixed member comprises a disc mounted on, or integral with, a respective part of the housing.

23. The vacuum pump arrangement according to claim 1 comprising means for cooling the fixed members.

24. The vacuum pump arrangement according to claim 23 wherein the cooling means comprises a plurality of cooling fins located on one side of each fixed member.

25. The vacuum pump arrangement according to claim 23 wherein the cooling means comprises means for supplying a flow of coolant to each fixed member.

26. The vacuum pump arrangement according to claim 1 comprising a cooling jacket extending about at least part of the multi-stage centrifugal compressor mechanism.

40. The vacuum pumping arrangement according to claim 37 comprising a bypass conduit connected between an exhaust from the booster pump and an exhaust from the backing pump, and means for controlling the flow of fluid through the bypass conduit.

41. A vacuum pump according to claim 37 wherein the molecular drag mechanism defines a plurality of flow channels that each receive fluid from a pump inlet and exhaust pumped fluid to a common exhaust port.

42. A vacuum pump according to claim 37 wherein the molecular drag mechanism is a multi-stage molecular drag mechanism.

43. A vacuum pump according to claim 42 wherein the stages of the drag mechanism are arranged in parallel.

38. (canceled)

39. (canceled)