# US 2014/0154123 A1 · Scroll Pump > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154123 A1 - Document ID: US20140154123A1 - Status: Published application - Kind: A1 - Application number: 14/233,026 - Filed: 2012-08-09 - Published: 2014-06-05 - Earliest claimed: 2011-08-11 - Assignees: Edwards Limited - Inventors: Ian David Stones; Miles Geoffery Hockliffe; Alan Ernest Kinnaird Holbrook - Web page: https://patentgrep.com/patent/US20140154123A1 ## CPC - F04C 28/24: characterised by using valves controlling pressure or flow rate, e.g. discharge valves {or unloading valves}(F04C28/10 takes precedence) - F01C 1/0215: {where only one member is moving} - F04C 18/0215: {where only one member is moving} - F04C 18/0246: {Details concerning the involute wraps or their base, e.g. geometry} - F04C 18/0253: {Details concerning the base} - F04C 25/02: for producing high vacuum (sealing arrangements F04C27/00; silencing F04C29/06) - F04C 28/26: using bypass channels - F04C 29/126: {of the non-return type} - F04C 23/008: {Hermetic pumps} - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS - F01C: ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES (internal-combustion aspects F02B53/00, F02B55/00) ## 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 3) The vacuum pump as claimed in claim 3, wherein the 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. ### Claim 5 (depends on 1) The vacuum pump as claimed in claim 1, wherein the scroll pumping mechanism 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 wherein the first location of the pumping channel is downstream of a transition between the first section and the second section. ### Claim 6 (depends on 5) The vacuum pump as claimed in claim 5, wherein the first location of the pumping channel is located less than one wrap of the pumping mechanism downstream of the transition. ### Claim 7 (depends on 5) The vacuum pump as claimed in claim 5, wherein the first section has a deeper pumping channel than the second section. ### Claim 8 (depends on 5) The vacuum pump as claimed in claim 5, wherein the first section comprises a plurality of said pumping channels extending in parallel from the scroll inlet, the pumping channels converging at the transition between the first and second sections to form a single pumping channel extending from the transition to the scroll outlet. ### Claim 9 (depends on 1) 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. ### Claim 10 (depends on 1) 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. ### Claim 11 (depends on 1) 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. ### Claim 12 (depends on 1) 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. ### Claim 13 (depends on 12) The vacuum pump as claimed in claim 12, wherein each of said gas conduits comprises one or more of said one-way valve arrangements. ### Claim 14 (depends on 1) 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. ### Claim 15 (depends on 1) The vacuum pump as claimed in claim 1, wherein during roughing the scroll inlet is at a pressure between 100 mbar and atmosphere.