EP3653881B1 - Twin shaft pump - Google Patents

Twin shaft pump Download PDF

Info

Publication number
EP3653881B1
EP3653881B1 EP19208771.6A EP19208771A EP3653881B1 EP 3653881 B1 EP3653881 B1 EP 3653881B1 EP 19208771 A EP19208771 A EP 19208771A EP 3653881 B1 EP3653881 B1 EP 3653881B1
Authority
EP
European Patent Office
Prior art keywords
twin shaft
pump
rotors
ceramic
rotor
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.)
Active
Application number
EP19208771.6A
Other languages
German (de)
French (fr)
Other versions
EP3653881A1 (en
Inventor
Ingo Stephen Graham
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 EP3653881A1 publication Critical patent/EP3653881A1/en
Application granted granted Critical
Publication of EP3653881B1 publication Critical patent/EP3653881B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

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
    • F04C18/08—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
    • 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
    • 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
    • F04C2230/00—Manufacture
    • F04C2230/90—Improving properties of machine parts
    • 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
    • F04C2230/00—Manufacture
    • F04C2230/90—Improving properties of machine parts
    • F04C2230/91—Coating
    • 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
    • F04C2240/00—Components
    • F04C2240/20—Rotors
    • 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
    • F05C2203/00—Non-metallic inorganic materials
    • F05C2203/08—Ceramics; Oxides

Definitions

  • the field of the invention relates to rotors for twin shaft pumps and to twin shaft pumps.
  • the properties required for rotors of twin shaft pumps depend on the pump's field of operation but may include: hardness which is particularly important where the gas being pumped comprises particulates; chemical resistance where aggressive chemicals are to be pumped; and temperature resistance where the temperature of the pump and/or the gases being pumped is high. Furthermore, low heat transfer properties may be desirable as may a low coefficient of thermal expansion or a similar coefficient of thermal expansion to that of the surrounding materials. In this way clearances, particularly between rotors mounted on twin shafts can be maintained while the temperature of the pump changes during operation.
  • rotors have been made of metal materials as these are relatively simple to manufacture into required forms using casting and standard industrial machining techniques, for example.
  • a metal is a relatively hard material, may operate at relatively high temperatures and may be corrosion resistant or may be treated to improve corrosion resistance.
  • the treatment of such metal materials to improve corrosion resistance may include coating.
  • the coating itself may lead to problems particularly during high temperature operation and/or operation in high particulate environments where the coating may become damaged and the rotor susceptible to wear.
  • a known rotor design is described in JP2005291135A . Similar twin shaft pumps are also known from GB 2 477 777 A , JP H03 100390 A , GB 2 501 302 A , DE 31 24 247 C1 and JP 2011 231750 A .
  • a first aspect provides a twin shaft pump according to claim 1.
  • Twin shaft pumps particularly those used as dry backing pumps in semiconductor processes are required to be hard, resistant to chemicals, in particular fluorine based gases and preferably suitable for high temperature operation.
  • Ceramics are known to be particularly hard materials that can have a low thermal conductivity and are suitable for high temperature operation. However, they have not conventionally been used as rotors in twin shaft pumps as they are both difficult and expensive to manufacture and their corrosion resistance and robustness is not proven in such situations. The failure of a rotor in such a system can cause significant damage to the pump and result in costly process downtime.
  • the inventor of the present invention determined that despite these technical prejudices, modern ceramics are chemically resistant to a sufficient level for pumping chemically aggressive gases such as fluorine, and that even were such a rotor to fail then the nature of ceramics is such that the failed rotor would be contained within a metal stator. Furthermore, their thermal coefficient of expansion which is similar to that of the materials supporting the shafts makes them particularly advantageous for twin shaft operation where the clearances between the rotors should be maintained across a temperature range. Thus, they determined that despite the technical prejudices, a ceramic rotor would be suitable for a twin shaft pump and would have many advantages.
  • said twin shaft pump is configured for operation in semiconductor processing, in a high particulate and chemically aggressive environment.
  • Twin shaft pumps may be used in semiconductor processing or DSL applications, in particular as backing or booster pumps for turbo molecular pumps.
  • Semiconductor processing involves process gases flowing through the chamber which gases may be full of particulate. Semiconductor processing also involves cleaning gases flowing through the chambers to clean the chambers. These gases are chemically very aggressive. Thus, vacuum pumps used in semiconductor processing applications are required to be both resistant to particulates and to chemically aggressive substances. In order for a pump to be resistant to particulates, the constituent parts and in particular the rotors should be formed of a material that is very hard. This hard material must also be resistant to any chemicals used during the cleaning cycle. A drawback of a particularly hard rotor is that it is difficult to machine.
  • Said rotor comprises a Zirconia Toughened Alumina type ceramic (ZTA)
  • ZTA Zircona Toughened Alumina
  • said rotor comprises a rotor for a Roots-type pump.
  • a rotor for a Roots type pump is relatively easy to balance and to manufacture to have the required clearances and as such the grinding step is less onerous than some rotor designs making a Roots type pump particularly applicable for a ceramic rotor.
  • said rotor comprises a rotor for a Northey-type pump.
  • a Northey-type or hook and claw rotor may also be formed from ceramics.
  • said rotor comprises a screw rotor for a twin-shaft screw pump.
  • said ceramic rotor is configured for operation above a temperature of 150°C. In other embodiments, said ceramic rotor is configured for operation between 100°C and 300°C.
  • the nature of the ceramic material forming the rotor makes it suitable for use at high temperatures.
  • it is thermally resistant, coping with high temperatures, and its thermal coefficient of expansion is low and may be similar to the material that supports the twin shafts and thus, any thermal expansion of the rotors substantially matches that of the shaft separation allowing clearances to be maintained across a temperature range.
  • the twin shaft pump comprises a dry pump. Dry pumps are often used in semiconductor processing where it is important that the processing chambers are kept clean and free from contaminants. With a dry pump the clearances are key to providing efficient pumping thus, forming a rotor of a substance with suitable thermal expansion properties and which is sufficiently hard to tolerate pumping a dusty gas makes a particularly effective rotor for a dry pump.
  • said twin shaft pump comprises a ceramic lined stator.
  • a ceramic rotor may extend the lifetime of a pump operating in a corrosive environment.
  • the stator may also be prone to corrosion and where the rotor is a ceramic rotor the stator may then become the limiting factor for the lifetime of the pump.
  • Providing a ceramic liner to the stator of such a pump will increase its resistance to corrosive and dusty environments, while the outer metal casing provides protection were the rotor to fail.
  • said pump is configured to operate as one of a backing or booster pump in semiconductor processing.
  • the rotor is particularly applicable in semiconducting processing as a backing or booster pump.
  • Chemical wear is particularly a problem at the exhaust end of a backing pump and thus, providing a backing pump with a ceramic rotor may increase its lifetime significantly and as such provide a significant advantage that more than compensates for any increase in initial costs.
  • said twin shaft pump is configured for pumping both chemically aggressive and dusty gases.
  • said chemically aggressive gas comprises a fluorine based gas, such as F 2 , NF 3 , F or CIF 3 .
  • ceramics are both chemically resistant and hard. They have been found to be particularly resistant to fluorine based gases which gases are used commonly in the cleaning cycles of a semiconductor processing system and which causes significant wear and performance loss on the rotors of conventional twin shaft pumps. Providing such pumps with ceramic rotors may significantly increase the lifetime and performance of the pump.
  • Figure 1 shows a twin shaft pump comprising ceramic rotors according to an embodiment.
  • Tests have demonstrated a ceramic's resistance to high partial pressures of aggressive semiconductor cleaning gasses (for example 20% F 2 at 250°C for in excess of 1200Hrs).
  • aggressive semiconductor cleaning gasses for example 20% F 2 at 250°C for in excess of 1200Hrs.
  • the use of a specific, but commercially available, ceramic material as a rotor in a dry pump, and in particular, in a twin shaft dry pump has been shown to be feasible.
  • the test results reveal a material lifetime capability, commensurate with typical pump service intervals for process applications, where large quantities of hard dusty process by-product are generated and where there is a subsequent aggressive cleaning cycle; the deployment of ceramic materials in the dry pump mechanism, effectively addresses the issue of 'chemical wear', that materials (which are either hard or chemically resistant, but not both) normally used in dry pumps, are subject to.
  • the tolerances of manufacture and thermal characteristics of the ceramic rotors make them particularly suitable for twin shaft pumps where the problem of maintaining tight clearances across a temperature range are particularly challenging.
  • ZTA Zirconia Toughened Alumina
  • Figure 1 shows two ceramic rotors 10 mounted within the stator 20 of a twin shaft Roots-type pump.
  • the rotors are manufactured such that the clearances x between the rotors 10 and those y between the rotors 10 and stator 20 are low (they are magnified in the Figure). This is possible due to the high tolerances of manufacture and owing to the sympathetic thermal expansion properties of the rotors and the other components of the pump, allowing these clearances not to change substantially across a temperature operating range.
  • the stator 20 is lined with a ceramic lining 22.
  • the ceramic lining provides a protective lining to the stator which protects the stator from the aggressive environment of the pumped gases.
  • the lining is located within the predominantly metal stator 20, which stator provides a protective compartment which would contain the rotor were it to fail.

Landscapes

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

Description

    FIELD OF THE INVENTION
  • The field of the invention relates to rotors for twin shaft pumps and to twin shaft pumps.
    • BACKGROUND
  • The properties required for rotors of twin shaft pumps depend on the pump's field of operation but may include: hardness which is particularly important where the gas being pumped comprises particulates; chemical resistance where aggressive chemicals are to be pumped; and temperature resistance where the temperature of the pump and/or the gases being pumped is high. Furthermore, low heat transfer properties may be desirable as may a low coefficient of thermal expansion or a similar coefficient of thermal expansion to that of the surrounding materials. In this way clearances, particularly between rotors mounted on twin shafts can be maintained while the temperature of the pump changes during operation.
  • Generally rotors have been made of metal materials as these are relatively simple to manufacture into required forms using casting and standard industrial machining techniques, for example. A metal is a relatively hard material, may operate at relatively high temperatures and may be corrosion resistant or may be treated to improve corrosion resistance. The treatment of such metal materials to improve corrosion resistance may include coating. The coating itself may lead to problems particularly during high temperature operation and/or operation in high particulate environments where the coating may become damaged and the rotor susceptible to wear. A known rotor design is described in JP2005291135A . Similar twin shaft pumps are also known from GB 2 477 777 A , JP H03 100390 A , GB 2 501 302 A , DE 31 24 247 C1 and JP 2011 231750 A .
  • It would be desirable to provide a rotor that was suitable for twin shaft pumps and that was both hard, chemically resistant and thermally stable.
    • SUMMARY
  • A first aspect provides a twin shaft pump according to claim 1.
  • Twin shaft pumps, particularly those used as dry backing pumps in semiconductor processes are required to be hard, resistant to chemicals, in particular fluorine based gases and preferably suitable for high temperature operation.
  • Ceramics are known to be particularly hard materials that can have a low thermal conductivity and are suitable for high temperature operation. However, they have not conventionally been used as rotors in twin shaft pumps as they are both difficult and expensive to manufacture and their corrosion resistance and robustness is not proven in such situations. The failure of a rotor in such a system can cause significant damage to the pump and result in costly process downtime.
  • The inventor of the present invention determined that despite these technical prejudices, modern ceramics are chemically resistant to a sufficient level for pumping chemically aggressive gases such as fluorine, and that even were such a rotor to fail then the nature of ceramics is such that the failed rotor would be contained within a metal stator. Furthermore, their thermal coefficient of expansion which is similar to that of the materials supporting the shafts makes them particularly advantageous for twin shaft operation where the clearances between the rotors should be maintained across a temperature range. Thus, they determined that despite the technical prejudices, a ceramic rotor would be suitable for a twin shaft pump and would have many advantages.
  • In some embodiments, said twin shaft pump is configured for operation in semiconductor processing, in a high particulate and chemically aggressive environment.
  • Twin shaft pumps may be used in semiconductor processing or DSL applications, in particular as backing or booster pumps for turbo molecular pumps.
  • Semiconductor processing involves process gases flowing through the chamber which gases may be full of particulate. Semiconductor processing also involves cleaning gases flowing through the chambers to clean the chambers. These gases are chemically very aggressive. Thus, vacuum pumps used in semiconductor processing applications are required to be both resistant to particulates and to chemically aggressive substances. In order for a pump to be resistant to particulates, the constituent parts and in particular the rotors should be formed of a material that is very hard. This hard material must also be resistant to any chemicals used during the cleaning cycle. A drawback of a particularly hard rotor is that it is difficult to machine. In this regard, prior to mounting within a twin shaft pump rotors need to be balanced and ground such that the when mounted in the pump the clearances between the rotors and between the rotors and stator, which clearances dictate the efficiency of the pump and its robustness, are provided to suitably high tolerances. Grinding a particularly hard material is difficult and in the case of ceramics requires diamond tools to perform the grinding. However, the advantages of ceramic materials in the manufacture of such rotors and in particular, their hardness and their unexpected resistance to chemicals particularly to fluorine based gases means that the elevated costs associated with their manufacture are more than compensated for by a substantial increase in the lifetime of the pump at least for some applications. Thus, for applications such as semiconducting processing a twin shaft pump with ceramic rotors is particularly advantageous.
    • Said rotor comprises a Zirconia Toughened Alumina type ceramic (ZTA)
  • Zircona Toughened Alumina (ZTA) has been found to be sufficiently hard and sufficiently resistant to fluorine to make it suitable for rotors of a pump used for semiconductor processing applications while being a material that can be manufactured and ground to the required shape and tolerances.
  • In some embodiments, said rotor comprises a rotor for a Roots-type pump.
  • A rotor for a Roots type pump is relatively easy to balance and to manufacture to have the required clearances and as such the grinding step is less onerous than some rotor designs making a Roots type pump particularly applicable for a ceramic rotor.
  • In other embodiments, said rotor comprises a rotor for a Northey-type pump.
  • A Northey-type or hook and claw rotor may also be formed from ceramics.
  • In still other embodiments, said rotor comprises a screw rotor for a twin-shaft screw pump.
  • In some embodiments, said ceramic rotor is configured for operation above a temperature of 150°C. In other embodiments, said ceramic rotor is configured for operation between 100°C and 300°C.
  • The nature of the ceramic material forming the rotor makes it suitable for use at high temperatures. In particular it is thermally resistant, coping with high temperatures, and its thermal coefficient of expansion is low and may be similar to the material that supports the twin shafts and thus, any thermal expansion of the rotors substantially matches that of the shaft separation allowing clearances to be maintained across a temperature range.
  • The twin shaft pump comprises a dry pump. Dry pumps are often used in semiconductor processing where it is important that the processing chambers are kept clean and free from contaminants. With a dry pump the clearances are key to providing efficient pumping thus, forming a rotor of a substance with suitable thermal expansion properties and which is sufficiently hard to tolerate pumping a dusty gas makes a particularly effective rotor for a dry pump.
  • In some embodiments said twin shaft pump comprises a ceramic lined stator.
  • The use of a ceramic rotor may extend the lifetime of a pump operating in a corrosive environment. However, in such an environment the stator may also be prone to corrosion and where the rotor is a ceramic rotor the stator may then become the limiting factor for the lifetime of the pump. Providing a ceramic liner to the stator of such a pump will increase its resistance to corrosive and dusty environments, while the outer metal casing provides protection were the rotor to fail.
  • In some embodiments, said pump is configured to operate as one of a backing or booster pump in semiconductor processing.
  • As noted previously, the rotor is particularly applicable in semiconducting processing as a backing or booster pump. Chemical wear is particularly a problem at the exhaust end of a backing pump and thus, providing a backing pump with a ceramic rotor may increase its lifetime significantly and as such provide a significant advantage that more than compensates for any increase in initial costs.
  • In some embodiments, said twin shaft pump is configured for pumping both chemically aggressive and dusty gases.
  • In some embodiments, said chemically aggressive gas comprises a fluorine based gas, such as F2, NF3, F or CIF3.
  • As mentioned previously ceramics are both chemically resistant and hard. They have been found to be particularly resistant to fluorine based gases which gases are used commonly in the cleaning cycles of a semiconductor processing system and which causes significant wear and performance loss on the rotors of conventional twin shaft pumps. Providing such pumps with ceramic rotors may significantly increase the lifetime and performance of the pump.
  • Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.
  • Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which:
    Figure 1 shows a twin shaft pump comprising ceramic rotors according to an embodiment.
    • DESCRIPTION OF THE EMBODIMENTS
  • Before discussing the embodiments in any more detail, first an overview will be provided.
  • Tests have demonstrated a ceramic's resistance to high partial pressures of aggressive semiconductor cleaning gasses (for example 20% F2 at 250°C for in excess of 1200Hrs). The use of a specific, but commercially available, ceramic material as a rotor in a dry pump, and in particular, in a twin shaft dry pump has been shown to be feasible. The test results reveal a material lifetime capability, commensurate with typical pump service intervals for process applications, where large quantities of hard dusty process by-product are generated and where there is a subsequent aggressive cleaning cycle; the deployment of ceramic materials in the dry pump mechanism, effectively addresses the issue of 'chemical wear', that materials (which are either hard or chemically resistant, but not both) normally used in dry pumps, are subject to.
  • There are certain Semicon and DSL applications where aspects of the process cycle require materials with extreme hardness, in order to cope with abrasive by-product and chemical resistance, in order to cope with aggressive cleans. Whilst there are materials which have one or other of these properties, there are few that have both. In particular, whilst the hardness of ceramic materials is known and whilst there was speculation that certain ceramic materials had a reasonable degree of Fluorine resistance, the extent of that chemical robustness (in terms of lifetime at partial pressure and temperature) was not established.
  • However, specific tests undertaken to ascertain the limits have shown that it would be worthwhile making rotors from these materials for these applications.
  • Furthermore, the tolerances of manufacture and thermal characteristics of the ceramic rotors make them particularly suitable for twin shaft pumps where the problem of maintaining tight clearances across a temperature range are particularly challenging.
  • One example of a ceramic material used in the production of these rotors is Zirconia Toughened Alumina (ZTA) type CeramTec DC 25. This material combines the pre-requisite hardness and chemical resistance, with thermal compatibility with other materials of construction within the pump.
  • Figure 1 shows two ceramic rotors 10 mounted within the stator 20 of a twin shaft Roots-type pump. The rotors are manufactured such that the clearances x between the rotors 10 and those y between the rotors 10 and stator 20 are low (they are magnified in the Figure). This is possible due to the high tolerances of manufacture and owing to the sympathetic thermal expansion properties of the rotors and the other components of the pump, allowing these clearances not to change substantially across a temperature operating range.
  • In this embodiment, the stator 20 is lined with a ceramic lining 22. The ceramic lining provides a protective lining to the stator which protects the stator from the aggressive environment of the pumped gases. The lining is located within the predominantly metal stator 20, which stator provides a protective compartment which would contain the rotor were it to fail.
  • Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.
    • REFERENCE SIGNS
    • 10
    ceramic rotors
    20
    stator
    22
    stator lining
    X
    clearances between rotors
    Y
    clearances between rotor and stator

Claims (7)

  1. A twin shaft pump comprising a pair of ceramic rotors (10), said twin shaft pump comprising a dry pump and being characterised in that said rotors (10) comprising a Zirconia Toughened Alumina type ceramic.
  2. A twin shaft pump according to claim 1, wherein said pump is configured to operate as one of a backing or booster pump in semiconductor processing.
  3. A twin shaft pump according to claim 1 or 2, wherein said twin shaft pump is configured for pumping both chemically aggressive and dusty gases.
  4. A twin shaft pump according to claim 3, wherein said chemically aggressive gas comprises a fluorine based gas, such as F2, NF3, F, CIF3.
  5. A twin shaft pump according to any preceding claim, said twin shaft pump comprising a stator (20) comprising a ceramic lining (22).
  6. A twin shaft pump according to any preceding claim, said ceramic rotors (10) being configured for operation above a temperature of 150°C.
  7. A twin shaft pump according to any of claims 1 to 5, said ceramic rotors (10) being configured for operation between 100°C and 300°C.
EP19208771.6A 2018-11-14 2019-11-13 Twin shaft pump Active EP3653881B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1818571.0A GB2578923B (en) 2018-11-14 2018-11-14 A rotor for a twin shaft pump and a twin shaft pump

Publications (2)

Publication Number Publication Date
EP3653881A1 EP3653881A1 (en) 2020-05-20
EP3653881B1 true EP3653881B1 (en) 2023-02-15

Family

ID=64739428

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19208771.6A Active EP3653881B1 (en) 2018-11-14 2019-11-13 Twin shaft pump

Country Status (2)

Country Link
EP (1) EP3653881B1 (en)
GB (1) GB2578923B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114658654B (en) * 2022-03-04 2023-08-15 中科仪(南通)半导体设备有限责任公司 Roots rotor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6354824B1 (en) * 2000-03-09 2002-03-12 Kudu Industries, Inc. Ceramic hardfacing for progressing cavity pump rotors

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3124247C1 (en) * 1981-06-19 1983-06-01 Boge Kompressoren Otto Boge Gmbh & Co Kg, 4800 Bielefeld Screw compressor
JPS59160084A (en) * 1983-03-02 1984-09-10 Nippon Denso Co Ltd Rotary fluid pressurizing and sending device
JPS62203990A (en) * 1986-03-03 1987-09-08 Ebara Res Co Ltd Roots-type pump
JPH03100390A (en) * 1989-09-12 1991-04-25 Hitachi Ltd Ceramic screw rotor and manufacture thereof
US5393209A (en) * 1993-03-29 1995-02-28 The United States Of America As Represented By The United States Department Of Energy Double-ended ceramic helical-rotor expander
JP2005291135A (en) * 2004-04-01 2005-10-20 Kyocera Corp Multistage positive-displacement vacuum pump and its manufacturing method
GB2426036A (en) * 2005-05-10 2006-11-15 Bernard Whicher Vertical Northey compressor
US8075293B2 (en) * 2007-05-23 2011-12-13 Eaton Corporation Rotary blower with corrosion-resistant abradable coating
GB2477777B (en) * 2010-02-12 2012-05-23 Univ City Lubrication of screw expanders
JP2011231750A (en) * 2010-04-30 2011-11-17 Miura Co Ltd Rotary pump for steam compression
CN102269168A (en) * 2011-08-25 2011-12-07 山东理工大学 Rotor pump zirconia ceramic cam wheel and preparation method thereof
GB2501302B (en) * 2012-04-19 2016-08-31 The City Univ Reduced noise screw machines
CN105782046A (en) * 2016-05-09 2016-07-20 北京中兴实强陶瓷轴承有限公司 Magnetic drive ceramic cam rotor pump

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6354824B1 (en) * 2000-03-09 2002-03-12 Kudu Industries, Inc. Ceramic hardfacing for progressing cavity pump rotors

Also Published As

Publication number Publication date
GB2578923A (en) 2020-06-03
EP3653881A1 (en) 2020-05-20
GB2578923B (en) 2021-05-26
GB201818571D0 (en) 2018-12-26

Similar Documents

Publication Publication Date Title
NL1021656C2 (en) Compressor unit with common housing for electric motor and compressor, method for manufacturing a partition for a compressor unit and use of a compressor unit.
TWI479078B (en) Multistage dry pump
US7819646B2 (en) Rotary piston vacuum pump with washing installation
WO1999057441A1 (en) Turbo-molecular pump with metal matrix composite rotor and stator
EP3653881B1 (en) Twin shaft pump
JP4637092B2 (en) Improved seal assembly
EP2499374B1 (en) Corrosion resistant shaft sealing for a vacuum pump
JP6390478B2 (en) Vacuum pump
KR20050050133A (en) Screw pump
US20160376905A1 (en) Sealing system for a steam turbine, and steam turbine
CN113383165A (en) Multistage turbomolecular pump
JP2005171766A (en) Dry pump and operating method of dry pump
US11143191B2 (en) Drag pump and a set of vacuum pumps including a drag pump
KR20120007014A (en) Vacuum pump
JP2006183465A (en) Centrifugal compressor
JPH11106343A (en) Displacement type pump
JP4661378B2 (en) Turbo molecular pump
Troup et al. Eli “il E-JéiollklP—I it Al _| TH E n—
JP2020070749A (en) Vacuum pump and vacuum pump component
JP2017031892A (en) Vacuum evacuation device and its operation method
JP2010098092A (en) Operation method of vacuum pump and method of manufacturing semiconductor device

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN PUBLISHED

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20201120

RBV Designated contracting states (corrected)

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20220908

RBV Designated contracting states (corrected)

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602019025242

Country of ref document: DE

REG Reference to a national code

Ref country code: AT

Ref legal event code: REF

Ref document number: 1548362

Country of ref document: AT

Kind code of ref document: T

Effective date: 20230315

Ref country code: IE

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG9D

P01 Opt-out of the competence of the unified patent court (upc) registered

Effective date: 20230505

REG Reference to a national code

Ref country code: NL

Ref legal event code: MP

Effective date: 20230215

REG Reference to a national code

Ref country code: AT

Ref legal event code: MK05

Ref document number: 1548362

Country of ref document: AT

Kind code of ref document: T

Effective date: 20230215

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230615

Ref country code: NO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230515

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: AT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: PL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230615

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230516

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SM

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 602019025242

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20231116

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20230215

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20231122

Year of fee payment: 5

Ref country code: IE

Payment date: 20231127

Year of fee payment: 5

Ref country code: FR

Payment date: 20231127

Year of fee payment: 5

Ref country code: DE

Payment date: 20231129

Year of fee payment: 5