Scroll pump with overpressure exhaust

Patent metadata

Field	Value
Publication number	US-9297384-B2
Application number	US-201214233026-A
Country	US
Kind code	B2
Filing date	Aug 9, 2012
Priority date	Aug 11, 2011
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

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.

First claim

The invention claimed is:

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.

2. The vacuum pump as claimed in claim 1 , wherein in a first condition of the pump during roughing when the scroll inlet is at or close to atmosphere the valve arrangement is closed, in a second condition when a predetermined pressure differential between the first and second locations of the pumping channel is generated during roughing the valve arrangement is open, and in a third condition when pressure at the scroll inlet is reduced below atmosphere and the pressure differential between the first and second locations of the pumping channel is less than the predetermined pressure the valve arrangement is closed.

3. The vacuum pump as claimed in claim 1 , wherein the one-way valve arrangement comprises two one-way valves located in the gas conduit for resisting the passage of gas through the conduit from the conduit inlet to the conduit outlet when closed and allowing the passage of gas through the conduit when open.

4. The vacuum pump as claimed in claim 3 , wherein the the one-way valve arrangement is arranged to prevent the passage of gas from the conduit outlet to the conduit inlet when the pressure at the conduit outlet is at least two orders of magnitude greater than the pressure at the conduit inlet.

5. The vacuum pump as claimed in claim 1 , wherein the inlet of the gas conduit is located less than one wrap of the pumping mechanism downstream of the transition.

6. The vacuum pump as claimed in claim 1 , wherein the first location of the pumping channel is between the scroll inlet and the scroll outlet and the second location of the pumping channel is at the scroll outlet.

7. The vacuum pump as claimed in claim 1 , wherein the first location of the pumping channel is between the scroll inlet and the scroll outlet and the second location of the pumping channel is at the scroll inlet.

8. The vacuum pump as claimed in claim 1 , wherein the first location of the pumping channel is between the scroll inlet and the scroll outlet and the second location of the pumping channel is between the scroll inlet and the scroll outlet.

9. The vacuum pump as claimed in claim 1 , comprising a plurality of said gas conduits connecting respective first conduit inlets with respective second conduit outlets.

10. The vacuum pump as claimed in claim 9 , wherein each of said gas conduits comprises one or more of said one-way valve arrangements.

11. The vacuum pump as claimed in claim 1 , wherein the two scrolls comprise a fixed scroll and an orbiting scroll and the or each gas conduit is formed in the fixed scroll.

12. The vacuum pump as claimed in claim 1 , wherein during roughing the scroll inlet is at a pressure between 100 mbar and atmosphere.

Assignees

• Stones Ian David
• Hockliffe Miles Geoffery
• Holbrook Alan Ernest Kinnaird
• Edwards Ltd

Inventors

• Stones Ian David
• Hockliffe Miles Geoffery
• Holbrook Alan Ernest Kinnaird

Classifications

• F04C28/26

  using bypass channels · CPC title

• F01C1/0215

  where only one member is moving · CPC title

• F04C29/126

  of the non-return type · CPC title

• F04C18/0215 Primary

  where only one member is moving · CPC title

• F04C23/008

  Hermetic pumps · CPC title