EP2126361A1 - Vacuum pump - Google Patents

Vacuum pump

Info

Publication number
EP2126361A1
EP2126361A1 EP08709648A EP08709648A EP2126361A1 EP 2126361 A1 EP2126361 A1 EP 2126361A1 EP 08709648 A EP08709648 A EP 08709648A EP 08709648 A EP08709648 A EP 08709648A EP 2126361 A1 EP2126361 A1 EP 2126361A1
Authority
EP
European Patent Office
Prior art keywords
pump
component
rotor
simo
ductile iron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08709648A
Other languages
German (de)
French (fr)
Inventor
Emmanuel Uzoma Okoroafor
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Edwards Ltd
Original Assignee
Edwards Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Edwards Ltd filed Critical Edwards Ltd
Publication of EP2126361A1 publication Critical patent/EP2126361A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C25/00—Adaptations of pumps for special use of pumps for elastic fluids
    • F04C25/02—Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
    • F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
    • F04C18/0215—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C18/123—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with radially or approximately radially from the rotor body extending tooth-like elements, co-operating with recesses in the other rotor, e.g. one tooth
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C18/126—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
    • F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2220/00—Application
    • F04C2220/10—Vacuum
    • F04C2220/12—Dry running
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0433—Iron group; Ferrous alloys, e.g. steel
    • F05C2201/0436—Iron
    • F05C2201/0439—Cast iron
    • F05C2201/0442—Spheroidal graphite cast iron, e.g. nodular iron, ductile iron
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/90—Alloys not otherwise provided for

Definitions

  • This invention relates to a dry vacuum pump.
  • Dry vacuum pumps are widely used in industrial processes to provide a clean and/or low -pressure environment for the manufacture of products. Applications include the pharmaceutical, semiconductor and flat panel manufacturing industries. Such pumps include an essentially dry (or oil free) pumping mechanism, but generally also include some components, such as bearings and transmission gears, for driving the pumping mechanism that require lubrication in order to be effective. Examples of dry pumps include Roots, Northey (or "claw"), screw and scroll pumps. Dry pumps incorporating Roots and/or Northey rotor components are commonly multi-stage positive displacement pumps comprising a stator component defining a plurality of pumping chambers each housing a respective pair of intermeshing rotor components. The rotor components are located on contra-rotating shafts, and may have the same type of profile in each chamber or the profile may change from chamber to chamber.
  • Iron castings have for a long time been used in the manufacture of stator and rotor components for dry vacuum pumps.
  • relatively corrosive gases such as chlorine, boron trichloride, hydrogen bromide, fluorine and chlorine trifluoride
  • Such corrosion can lead to equipment failure, leakage of process gases and possible process contamination, in addition to the costs associated with the replacement of the pump or the corroded parts and consequential process downtime.
  • the present invention provides at least one dry vacuum pump stator component, wherein the stator component is formed from silicon-molybdenum (SiMo) ductile iron alloy.
  • the present invention also provides at least one dry vacuum pump rotor component, wherein the rotor component is formed from silicon-molybdenum (SiMo) ductile iron alloy.
  • the present invention also provides a dry vacuum pump comprising a stator component and at least one rotor component, wherein the stator component and/or said at least one rotor component are formed from silicon-molybdenum (SiMo) ductile iron alloy.
  • SiMo silicon-molybdenum
  • the alloy may contain silicon in an amount from about 3.5 to about 5 wt %.
  • the alloy may contain molybdenum in an amount from about 0.4 to about 1 wt %.
  • the stator component may house first and second intermeshing rotor components adapted for counter-rotation within the stator component.
  • the rotor components have a Roots profile, although they could have a Northey or screw profile as required.
  • the pump may be in the form of a multi-stage pump in which the stator component defines a plurality of interconnected pumping chambers arranged in series and each housing respective rotor components formed from SiMo ductile iron alloy.
  • the intermeshing rotor components may be located on respective shafts, with the pump comprising a gear assembly for transmitting torque from one shaft to another, with at least one gear of the gear assembly preferably being formed from SiMo ductile iron alloy.
  • the pump may be in the form of a scroll pump in which the stator component comprises a fixed scroll member having an end plate with a first spiral wrap extending therefrom, and said at least one rotor component comprises an orbital scroll member having an end plate with a second spiral wrap extending therefrom to intermesh with the first spiral wrap.
  • the scroll members is preferably formed from SiMo iron alloy.
  • Figure 1 is a cross-section through a multi-stage dry vacuum pump
  • Figure 2 is a view along line A-A in Figure 1.
  • a multi-stage dry vacuum pump 10 comprises a stator component 12, preferably formed from silicon-molybdenum (SiMo) ductile iron alloy, having a series of walls that define a plurality of pumping chambers 14, 16, 18, 20, 22.
  • An inlet conduit 24 for conveying gas to be pumped to the inlet pumping chamber 14, and an exhaust conduit 26 for exhausting pumped gas from the exhaust pumping chamber 22, are also formed in the stator 12.
  • Passages 28, 30, 32 and 34 formed in the stator 12 connect the pumping chambers 14, 16, 18, 20, 22 in series.
  • the stator 12 houses a first shaft 36 and, spaced therefrom and parallel thereto, a second shaft 38. Bearings 40 for supporting the shafts 36, 38 are provided in the end plates 42, 44 of the stator 12.
  • One of the shafts 36 is connected to a drive motor 46, the shafts being coupled together by means of timing gears 47 so that in use the shafts 36,38 rotate at the same speed but in opposite directions, as indicated by arrows 48 and 50 in Figure 2.
  • a gear box 52 attached to the side of the pump 10 contains oil 54 for lubricating the timing gears 47.
  • the timing gears 47 may be formed from SiMo ductile iron alloy.
  • the shafts 36, 38 support respective rotor components 56, 58, which may also be formed from SiMo ductile iron alloy.
  • the rotors 56, 58 have a Roots-type profile within each pumping chamber, although a mixture of Roots and Northey-type profiles may be provided within the pump 10.
  • the rotors 56, 58 are located in each pumping chamber relative to an internal surface of the stator 12 such that the rotors 56, 58 can act in an intermeshing manner known per se.
  • gas is urged into the pump 10 through the inlet conduit 24 and passes into the inlet pumping chamber 14.
  • the gas is compressed by the rotors 56, 58 located within the inlet pumping chamber 14, and is fed by passage 28 into the next pumping chamber 16.
  • the gas fed in the pumping chamber 16 is similarly compressed by the rotors 56, 58 therein, and fed by the passage 30 to the next pumping chamber 18. Similar gas compressions take place in the pumping chambers 18, 20 and 22, with the pumped gas finally being exhaust from the pump 10 through exhaust conduit 26.
  • the SiMo ductile iron alloy preferably contains silicon from about 3.5 to about 5 wt %, and/or molybdenum in an amount from about 0.4 to about 1 wt %.
  • SiMo ductile iron alloy to manufacture the stator component 12 and/or the rotor components 56, 58 of the pump 10 makes the pump 10 particularly suitable for pumping corrosive gases such as chlorine, boron trichloride, hydrogen bromide, fluorine and chlorine trifluoride.
  • SiMo ductile iron alloy has superior hardness, specific strength ratio and F 2 corrosion susceptibility. This can enable the stator and rotor components, and the timing gears, to have relatively high wear and corrosion resistance with reduced component weight and costs for equivalent or improved performances.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Abstract

A dry vacuum pump comprises a stator component and at least one rotor component. To improve the tolerance of the pump to corrosive gases passing through the pump, the stator component and/or said at least one rotor component are formed from silicon-molybdenum (SiMo) ductile iron.

Description

VACUUM PUMP
This invention relates to a dry vacuum pump.
Dry vacuum pumps are widely used in industrial processes to provide a clean and/or low -pressure environment for the manufacture of products. Applications include the pharmaceutical, semiconductor and flat panel manufacturing industries. Such pumps include an essentially dry (or oil free) pumping mechanism, but generally also include some components, such as bearings and transmission gears, for driving the pumping mechanism that require lubrication in order to be effective. Examples of dry pumps include Roots, Northey (or "claw"), screw and scroll pumps. Dry pumps incorporating Roots and/or Northey rotor components are commonly multi-stage positive displacement pumps comprising a stator component defining a plurality of pumping chambers each housing a respective pair of intermeshing rotor components. The rotor components are located on contra-rotating shafts, and may have the same type of profile in each chamber or the profile may change from chamber to chamber.
Iron castings have for a long time been used in the manufacture of stator and rotor components for dry vacuum pumps. However, in the semiconductor industries the increasing use of high flow rates of relatively corrosive gases such as chlorine, boron trichloride, hydrogen bromide, fluorine and chlorine trifluoride has lead to severe corrosion, and therefore relatively short lifetime, of, cast iron stator and rotor components. Such corrosion can lead to equipment failure, leakage of process gases and possible process contamination, in addition to the costs associated with the replacement of the pump or the corroded parts and consequential process downtime.
In view of this, it is known to passively protect these components by the formation of a resin or polymeric coating of a fluoropolymer or polyimide material on the component surfaces which are exposed to the corrosive gases. Such coatings have a tendency to degrade with time, with the resultant peeling or flaking of the coating exposing the underlying cast iron to the corrosive gases. Another alternative is to form these components from a nickel-rich cast iron, for example ductile Ni-resist, or a stainless steel having superior corrosion resistance. However, Ni-resist cast iron and stainless steel are relatively expensive and difficult to machine, and so do not provide cost-effective options for use in the manufacture of the rotor and stator components.
The present invention provides at least one dry vacuum pump stator component, wherein the stator component is formed from silicon-molybdenum (SiMo) ductile iron alloy.
The present invention also provides at least one dry vacuum pump rotor component, wherein the rotor component is formed from silicon-molybdenum (SiMo) ductile iron alloy.
The present invention also provides a dry vacuum pump comprising a stator component and at least one rotor component, wherein the stator component and/or said at least one rotor component are formed from silicon-molybdenum (SiMo) ductile iron alloy.
The alloy may contain silicon in an amount from about 3.5 to about 5 wt %. The alloy may contain molybdenum in an amount from about 0.4 to about 1 wt %.
The stator component may house first and second intermeshing rotor components adapted for counter-rotation within the stator component. In the preferred embodiment, the rotor components have a Roots profile, although they could have a Northey or screw profile as required.
The pump may be in the form of a multi-stage pump in which the stator component defines a plurality of interconnected pumping chambers arranged in series and each housing respective rotor components formed from SiMo ductile iron alloy. The intermeshing rotor components may be located on respective shafts, with the pump comprising a gear assembly for transmitting torque from one shaft to another, with at least one gear of the gear assembly preferably being formed from SiMo ductile iron alloy.
Alternatively, the pump may be in the form of a scroll pump in which the stator component comprises a fixed scroll member having an end plate with a first spiral wrap extending therefrom, and said at least one rotor component comprises an orbital scroll member having an end plate with a second spiral wrap extending therefrom to intermesh with the first spiral wrap. Each of the scroll members is preferably formed from SiMo iron alloy.
Preferred features of the present invention will now be described, by way of example only, with reference to the following drawings, in which:
Figure 1 is a cross-section through a multi-stage dry vacuum pump; and
Figure 2 is a view along line A-A in Figure 1.
With reference to Figures 1 and 2, a multi-stage dry vacuum pump 10 comprises a stator component 12, preferably formed from silicon-molybdenum (SiMo) ductile iron alloy, having a series of walls that define a plurality of pumping chambers 14, 16, 18, 20, 22. An inlet conduit 24 for conveying gas to be pumped to the inlet pumping chamber 14, and an exhaust conduit 26 for exhausting pumped gas from the exhaust pumping chamber 22, are also formed in the stator 12. Passages 28, 30, 32 and 34 formed in the stator 12 connect the pumping chambers 14, 16, 18, 20, 22 in series.
The stator 12 houses a first shaft 36 and, spaced therefrom and parallel thereto, a second shaft 38. Bearings 40 for supporting the shafts 36, 38 are provided in the end plates 42, 44 of the stator 12. One of the shafts 36 is connected to a drive motor 46, the shafts being coupled together by means of timing gears 47 so that in use the shafts 36,38 rotate at the same speed but in opposite directions, as indicated by arrows 48 and 50 in Figure 2. A gear box 52 attached to the side of the pump 10 contains oil 54 for lubricating the timing gears 47. The timing gears 47 may be formed from SiMo ductile iron alloy.
Within each pumping chamber, the shafts 36, 38 support respective rotor components 56, 58, which may also be formed from SiMo ductile iron alloy. In this embodiment, the rotors 56, 58 have a Roots-type profile within each pumping chamber, although a mixture of Roots and Northey-type profiles may be provided within the pump 10. The rotors 56, 58 are located in each pumping chamber relative to an internal surface of the stator 12 such that the rotors 56, 58 can act in an intermeshing manner known per se.
In use, gas is urged into the pump 10 through the inlet conduit 24 and passes into the inlet pumping chamber 14. The gas is compressed by the rotors 56, 58 located within the inlet pumping chamber 14, and is fed by passage 28 into the next pumping chamber 16. The gas fed in the pumping chamber 16 is similarly compressed by the rotors 56, 58 therein, and fed by the passage 30 to the next pumping chamber 18. Similar gas compressions take place in the pumping chambers 18, 20 and 22, with the pumped gas finally being exhaust from the pump 10 through exhaust conduit 26.
The SiMo ductile iron alloy preferably contains silicon from about 3.5 to about 5 wt %, and/or molybdenum in an amount from about 0.4 to about 1 wt %.
The use of SiMo ductile iron alloy to manufacture the stator component 12 and/or the rotor components 56, 58 of the pump 10 makes the pump 10 particularly suitable for pumping corrosive gases such as chlorine, boron trichloride, hydrogen bromide, fluorine and chlorine trifluoride. In comparison to the more expensive Ni- resist material, which are currently around four to five times more expensive than SiMo ductile iron alloy, SiMo ductile iron alloy has superior hardness, specific strength ratio and F2 corrosion susceptibility. This can enable the stator and rotor components, and the timing gears, to have relatively high wear and corrosion resistance with reduced component weight and costs for equivalent or improved performances.

Claims

1. A dry vacuum pump stator component, wherein the stator component is formed from silicon-molybdenum (SiMo) ductile iron alloy.
2. A dry vacuum pump rotor component, wherein the rotor component is formed from silicon-molybdenum (SiMo) ductile iron alloy.
3. A dry vacuum pump comprising a stator component and at least one rotor component, wherein the stator component and/or said at least one rotor component are formed from silicon-molybdenum (SiMo) ductile iron alloy according to Claim 1 and/or Claim 2.
4. A pump according to Claim 3, wherein the alloy contains silicon in an amount from about 3.5 to about 5 wt %.
5. A pump according to Claim 3 and Claim 4, wherein the alloy contains molybdenum in an amount from about 0.4 to about 1 wt %.
6. A pump according to Claim 3 and Claim 4, wherein said at least one rotor component has one of a screw, Roots or Northey profile.
7. A pump according to Claim 6, comprising first and second intermeshing rotor components adapted for counter-rotation within the stator component.
8. A pump according to Claim 7, wherein intermeshing rotor components are located on respective shafts, the pump comprising a gear assembly for transmitting torque from one shaft to another, at least one gear of the gear assembly being formed from SiMo ductile iron alloy.
9. A pump according to claims 3 to 8, in the form of a multi-stage dry vacuum pump in which the stator component defines a plurality of interconnected pumping chambers each housing a respective pair of rotor components each formed from SiMo ductile iron alloy.
10. A pump according to any of Claims 3 to 5, in the form of a scroll pump in which the stator component comprises a fixed scroll member having an end plate with a first spiral wrap extending therefrom, and said at least one rotor component comprises an orbital scroll member having an end plate with a second spiral wrap extending therefrom to intermesh with the first spiral wrap.
EP08709648A 2007-03-28 2008-02-26 Vacuum pump Withdrawn EP2126361A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0705971.0A GB0705971D0 (en) 2007-03-28 2007-03-28 Vacuum pump
PCT/GB2008/050128 WO2008117082A1 (en) 2007-03-28 2008-02-26 Vacuum pump

Publications (1)

Publication Number Publication Date
EP2126361A1 true EP2126361A1 (en) 2009-12-02

Family

ID=38050354

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08709648A Withdrawn EP2126361A1 (en) 2007-03-28 2008-02-26 Vacuum pump

Country Status (6)

Country Link
US (1) US20100178187A1 (en)
EP (1) EP2126361A1 (en)
JP (1) JP2010522843A (en)
KR (1) KR20100014610A (en)
GB (1) GB0705971D0 (en)
WO (1) WO2008117082A1 (en)

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JP2010522843A (en) 2010-07-08
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