EP3728857A1 - Magnetic shield for a vacuum pump - Google Patents
Magnetic shield for a vacuum pumpInfo
- Publication number
- EP3728857A1 EP3728857A1 EP18829445.8A EP18829445A EP3728857A1 EP 3728857 A1 EP3728857 A1 EP 3728857A1 EP 18829445 A EP18829445 A EP 18829445A EP 3728857 A1 EP3728857 A1 EP 3728857A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- vacuum pump
- magnetic shield
- pump
- envelope
- channel
- 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.)
- Pending
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 158
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 16
- 239000012809 cooling fluid Substances 0.000 claims description 16
- 239000012530 fluid Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 12
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- 238000003754 machining Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 5
- 239000011265 semifinished product Substances 0.000 claims description 4
- 238000000137 annealing Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000000047 product Substances 0.000 claims description 2
- 239000007779 soft material Substances 0.000 description 7
- 230000004907 flux Effects 0.000 description 5
- 238000013021 overheating Methods 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000004323 axial length Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 229910001105 martensitic stainless steel Inorganic materials 0.000 description 3
- 239000011800 void material Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 230000005355 Hall effect Effects 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D19/00—Axial-flow pumps
- F04D19/02—Multi-stage pumps
- F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D19/00—Axial-flow pumps
- F04D19/02—Multi-stage pumps
- F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
- F04D19/042—Turbomolecular vacuum pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/02—Selection of particular materials
- F04D29/023—Selection of particular materials especially adapted for elastic fluid pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/52—Casings; Connections of working fluid for axial pumps
- F04D29/522—Casings; Connections of working fluid for axial pumps especially adapted for elastic fluid pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/60—Mounting; Assembling; Disassembling
- F04D29/601—Mounting; Assembling; Disassembling specially adapted for elastic fluid pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2300/00—Materials; Properties thereof
- F05D2300/50—Intrinsic material properties or characteristics
- F05D2300/507—Magnetic properties
Definitions
- the present invention relates to magnetic shielding of vacuum pumps and, in particular, to the magnetic shielding of turbomolecular pumps. Background to the Invention
- Turbomolecular pumps are used to provide ultra-high vacuums in a range of applications.
- a turbomolecular pump will comprise a pump envelope in which the rotor cavity is located.
- Each rotor cavity may contain a group of one or more stators and corresponding rotors supported on an impeller shaft. At full speed the impeller will spin about its axis at about 60,000 rpm to evacuate a vacuum chamber.
- turbomolecular pumps may be located in close proximity to DC magnetic fields of sufficient strength to disrupt the normal working of the pump mechanism.
- turbomolecular pumps with martensitic stainless-steel pump envelopes have been developed for operation in radial DC magnetic fields with a peak strength of up to 35 mT.
- a martensitic stainless-steel envelope will typically ensure that the average (mean) magnetic field strength within the rotor cavity does not exceed 6 mT.
- turbomolecular pumps that can run at full rotational speed in radial DC magnetic fields with a mean strength of 100 mT: such as those found in close proximity to mass spectrometers and superconducting magnets.
- the present invention provides a magnetically shielded vacuum pump comprising a pump envelope covering the rotor cavity; at least one outer magnetic shield circumferentially encasing at least a portion of the pump envelope; and a longitudinally extending circumferential channel between the encased portion of the pump envelope and the at least one outer magnetic shield.
- the longitudinally extending circumferential channel may have a generally annular cross-section, and circumferentially surrounds the encased portion of the envelope.
- the encased portion of the pump envelope extends at least the length of the rotor cavity of the pump.
- the rotor cavity will be located fully within the encased portion of the pump envelope.
- the shielded pump when in use, will not exceed its maximum operating temperature when it is run with the centre of the pump inlet placed in a radial DC magnetic field, which is normal to the axis of rotation of the pump rotor, with a peak strength of 300 mT or greater, preferably from about 300 mT to about 500 mT.
- the average magnetic field strength in the rotor cavity does not exceed about 6 mT, preferably 5 mT, when the centre of the pump inlet of the vacuum pump is placed in a radial DC magnetic field, which is normal to the axis of rotation of the pump rotor, with a peak strength of 300 mT or greater, preferably from about 300 mT to about 500 mT, at an outside surface of the magnetic shield.
- the pump may be configured such that, in use, a shielded pump can operate, e.g.
- the centre of the pump inlet is placed in a radial DC magnetic field, that is normal to the axis of rotation of the pump rotor, with a mean radial field strength of 100 mT.
- the average magnetic field strength within the rotor cavity of the vacuum pump does not exceed an average of about 6 mT, preferably it does not exceed about 5 mT.
- the longitudinally extending circumferential channel between the encased portion of the pump and the outer magnetic shield provides a void between the shield and the envelope so that they may be totally separate, thereby reducing the magnetic flux that passes from the shield to the envelope. Accordingly, the combined shield and envelope guide the magnetic flux around the vacuum pump rotor cavity, reducing the Eddy currents induced by the rotor.
- the void typically has a substantially annular cross-section.
- a fluid such as air
- the fluid may be pumped along the channel to cool the vacuum pump.
- the fluid may be pumped across an outer surface of the encased portion of the pump, preferably substantially all of the outer surface of the encased portion of the pump, preferably across an outside surface of the pump envelope.
- the fluid for cooling the vacuum pump contacts an outer surface of the pump envelope.
- the fluid may be pumped from a first end to a second end of the channel, preferably in a direction substantially parallel to the axis of rotation of the pump rotor, preferably in a direction substantially towards the inlet end of the rotor cavity.
- the fluid may be pumped from a first end to a second end such that the fluid is travelling in a direction substantially opposing the action of gravity. Such arrangements may assist filling the channel uniformly.
- the fluid entering the channel may be at a temperature of from about 10 °C to about 40 °C, more preferably from about 20 °C to about 30 °C, for example 22 °C.
- the cooling fluid temperature and flow rate may be selected to maintain the pump at a temperature below its maximum operating temperature.
- the fluid may preferably be a gas, such as air.
- the air at room temperature (22°C).
- the pump envelope and/or magnetic shield may comprise a magnetically soft material.
- a magnetically soft material may be understood to be a ferromagnetic material with a coercivity less than 1000 A/m. Additionally, or alternatively, the magnetically soft material has a relative permeability of from about 400 and to about 4500. Preferably the magnetically soft material has a saturation flux density of at least about 1.8T.
- magnetic shields comprising such magnetically soft material may be relatively compact whilst still providing effective shielding in a high strength magnetic field.
- the envelope and/or outer magnetic shield may comprise pure iron or a mild-steel, i.e. less than 0.2% carbon, preferably from about 0.05% to about 0.2% carbon.
- Preferred steels include 070M20 and PD970-3.
- the steel is fully annealed before the shield and/or envelope are machined. However, typically, no further heat treatments are employed after machining.
- this process greatly reduces the cost of the components and whilst the process may leave a magnetically hard surface as a result of work hardening, this in turn can be addressed by increasing the specified radial thickness of the components by about 2 mm.
- the envelope and/or outer magnetic shield is electroless nickel plated.
- this reduces H2 diffusion through the envelope and allows standard sealing geometries to be employed.
- the envelope and outer magnetic shield may comprise substantially the same magnetically soft material.
- different shaped outer magnetic shields may be employed to magnetically shield the rotor cavity of a vacuum pump. In an embodiment, the whole of the vacuum pump may be encased; however, from a practical perspective this may not always be possible.
- the outer magnetic shield is a hollow open-ended generally cylindrical body with a substantially annular cross-section, e.g. a tube, that fits around the pump envelope. Whilst the pump envelope and/or magnetic shield and/or channel may have a substantially annular cross-section, it will be appreciated that other cross-sections may also be employed.
- the outer magnetic shield may be castellated to aid the flow of fluid into and/or out of the longitudinally extending channel.
- the outer magnetic shield comprises two or more longitudinally extending sections, preferably two longitudinally extending sections. Typically, each section has a mass of less than 25 Kg, preferably less than about 15 Kg.
- a segmented shield may allow the shield to be fitted around services that must penetrate the shield e.g. pipe and cable connections.
- One or more of the sections may have a semi-annular cross-section.
- the sections may be placed together to form a hollow cylindrical body.
- the mating faces of the sections are configured to fit sufficiently closely together that a magnetic circuit is substantially maintained across the joint extending therebetween.
- the two or more sections will be clamped or otherwise non- permanently adjoined to one another for use.
- the non-permanent fixation will be able to withstand sufficient force to prevent the sections separating under the action of the magnetic field.
- the non-permanent fixation may hold the two or more parts together with a force of greater than about 300 N, preferably from about 350 N to about 500 N.
- the pump envelope wall has a radial thickness of at least about 8 mm, preferably from about 10 mm to about 25 mm. 11 mm is an example. Even without an outer magnetic shield, when placed in a radial DC magnetic field with a maximum peak strength of 35 mT, a vacuum pump with an 11 mm fully annealed mild-steel pump envelope may provide a rotor cavity containing a magnetic field with a mean strength of less than 6 mT, typically a mean field strength of less than 5 mT.
- the outer magnetic shield has a radial thickness of at least about 15 mm, preferably from about 20 mm to about 40 mm. 20 mm being an example.
- the longitudinally extending circumferential channel has a radial thickness of at least about 3 mm, preferably from about 5 mm to about 40 mm. 5mm is an example. The greater the thickness of the longitudinally extending circumferential channel, the better the magnetic shielding provided to the rotor cavity because the magnetic flux will tend to move around the outer magnetic shield rather than across the void provided by the channel.
- the radial thicknesses of the outer magnetic shield, channel and/or envelope may each be optimised depending upon the specific vacuum pump, its geometries, and its intended application. Typically, the radial thicknesses will be optimised to ensure the average magnetic field within the rotor cavity of the vacuum pump does not exceed a mean field strength of 6 mT, preferably 5 mT, when the centre of the pump inlet is placed in a specific peak radial DC magnetic field that is normal to the axis of rotation of the pump.
- the vacuum pump may comprise more than one outer magnetic shield, for instance 2, 3, 4, 5 or more substantially concentrically aligned outer magnetic shields, each of incrementally increasing diameter.
- outer magnetic shields for instance 2, 3, 4, 5 or more substantially concentrically aligned outer magnetic shields, each of incrementally increasing diameter.
- longitudinally extending circumferential channels are provided between each outer magnetic shield layer and those adjacent.
- a fluid such as a gas e.g. air, may be pumped along each of said longitudinally extending circumferential channels.
- a fluid such as a gas e.g. air
- outer magnetic shield is to be understood as a magnetic shield that circumferentially encases at least a portion of the pump envelope. The skilled person will understand that this does not necessarily mean it is the outermost magnetic shield, however this may be the case in embodiments. For example, in configurations in which the vacuum pump comprises multiple outer magnetic shields, only the furthest from the vacuum pump envelope may be the outermost, but the skilled person will understand that“outer magnetic shield” can refer to any of the shields surrounding the vacuum pump envelope. Equally, in embodiments comprising a single outer magnetic shield, said shield will be the outermost magnetic shield.
- the magnetic field within the pump envelope, and in particular the rotor cavity does not exceed an average (mean) of about 6 mT, preferably it does not exceed about 5 mT.
- the present invention provides a magnetic shielding assembly for increasing the magnetic shielding of a vacuum pump already configured to operate in DC magnetic fields with a peak radial field strength of up to 35 mT.
- a vacuum pump with a ferromagnetic pump envelope for instance a martensitic stainless steel or electroless nickel plated mild-steel pump envelope.
- the assembly may comprise an outer magnetic shield for circumferentially enclosing a portion of the vacuum pump, said outer magnetic shield having an inner wall which, in use, defines an outer surface of a longitudinally extending substantially annular channel.
- the outer magnetic shield comprises a magnetically soft material, with a coercivity less than 1000 A/m. Additionally, or alternatively, a relative permeability of between 400 and 4500. Preferably a saturation flux density of at least about 1.8 T.
- the assembly may be configured such that, in use, a shielded pump can operate when the centre of the pump inlet is placed in a radial DC magnetic field, that is normal to the axis of rotation of the pump rotor, with a mean radial field strength of 100 mT.
- the average magnetic field strength within the rotor cavity of the vacuum pump does not exceed an average of about 6 mT, preferably it does not exceed about 5 mT.
- the assembly may be configured such that, in use, the shielded pump can operate in DC magnetic fields with a peak radial field strength of up to about 500 mT, preferably from about 300 mT to about 400 mT, directly adjacent the outer surface of the magnetic shield.
- the average magnetic field strength within the rotor cavity of the vacuum pump does not exceed an average of about 6 mT, preferably it does not exceed about 5 mT.
- the outer magnetic shield will typically be a hollow substantially cylindrical body.
- the outer magnetic shield will typically have an inner diameter greater than the outer diameter of the vacuum pump’s envelope. Additionally, or alternatively, the difference in diameters between the pump envelope and outer magnetic shield provide the circumferential channel between the two.
- the outer magnetic shield will have an axial length the same or greater than the rotor cavity of the vacuum pump.
- the outer magnetic shield may comprise two or more sections, for instance 2, 3, 4 or 5, or more sections. Typically, the sections extend the full axial length of the shield but only partially circumferentially. In a preferred embodiment, the shield comprises at least one semi-annular section. Typically, no individual section has a mass of more than 25 Kg, preferably no more than 15 Kg.
- the channel may be used to direct a cooling fluid, preferably gas, e.g. air, between the outer magnetic shield and the vacuum pump. Preferably, the cooling fluid may be pumped across the outer surface of the pump envelope. The channel also increases the shielding provided by the outer magnetic shield compared to if the outer magnetic shield and pump envelope were in direct contact.
- the combination of the channel and the cooling fluid may provide increased magnetic shielding without overheating.
- the outer magnetic shield may comprise a mild steel, preferably a fully annealed mild steel.
- the surfaces of the outer magnetic shield may be work hardened during machining; however, typically, no further heat treatment is performed following machining.
- the outer magnetic shield has a radial thickness of at least about 15 mm; and/or the longitudinally extending circumferential channel has a radial thickness of at least 3 mm.
- the present invention provides a magnetic shield for a vacuum pump, the shield comprising a main body configured to enclose a portion of the vacuum pump and a channel configured to receive a fluid for cooling the vacuum pump.
- the channel directs the cooling fluid across an outer surface of the pump, preferably between the shield and the vacuum pump.
- the channel circumferentially encloses the portion of the vacuum pump enclosed by the shield.
- an inner surface of the outer magnetic shield provides an outer surface of the cooling channel and/or an outer surface of the pump provides an inner surface of the cooling channel.
- the fluid is a gas such as air, preferably at room temperature.
- the vacuum pump is a turbomolecular pump.
- the cooling fluid temperature and flow rate is selected to maintain the pump at a preferred operating temperature.
- the main body has a radial thickness of at least about 15 mm; and/or the cooling channel has a radial thickness of at least about 3 mm.
- the present invention provides a method for manufacturing a magnetic shield for a vacuum pump.
- the method comprises the steps of providing a mild-steel semi-finished product; fully annealing said semi-finished product; and machining a magnetic shield, or segment thereof, from said fully annealed product; wherein following the machining step no further heat treatments are performed before the magnetic shield, or segment thereof, is attached to the vacuum pump.
- the process may be used to manufacture the envelope of a turbomolecular pump and/or an outer magnetic shield for surrounding the envelope of a turbomolecular pump as described elsewhere in this application.
- Fully annealing the steel may include heating the steel to a temperature where all the ferrite contained therein transforms to austenite. The material is then allowed to cool very slowly to room temperature (e.g. 22 °C) so as to ensure that the equilibrium microstructure is obtained and all austenite is transformed to pearlite and ferrite with a coarse grain structure.
- the magnetic shield is an envelope of a turbomolecular pump
- the envelope may subsequently be electroless nickel plated.
- the invention also provides a vacuum pump comprising a magnetic shield manufactured according to said process.
- Fig. 1 shows a section through a turbomolecular pump according to the invention.
- Fig. 2 shows a turbomolecular pump with the outer magnetic shield removed.
- the present invention provides vacuum pumps comprising magnetic shields.
- a turbomolecular pump (1 ) comprises an outer magnetic shield (2), a pump envelope (3) and a longitudinally extending circumferential channel (4).
- the pump envelope (3), outer magnetic shield (2), and channel (4) are substantially concentrically aligned about a longitudinal axis (A) of the turbomolecular pump.
- “axial”,“axially” and“axial direction” refer to a direction parallel to the axis“A” of the turbomolecular pump.
- the direction will typically be normal to the radial thickness of pump envelope (3), channel (4), and/or outer magnetic shield (2), and generally parallel to the outer surface of the pump envelope and inner surface of the shield.
- the outer magnetic shield (2) may have a radial thickness (a) that is greater than the radial thickness (b) of the pump envelope (3) and the radial thickness (c) of the channel (4).
- the outer magnetic shield (2) has a radial thickness (a) of at least 15 mm, preferably at least 20 mm.
- the exemplified outer magnetic shield (2) has an axial length (x) that is greater than the axial length (y) of the rotor cavity (5).
- this ensures that substantially all of the rotor cavity (5) will be shielded from a surrounding magnetic field.
- the average magnetic field strength inside the shielded rotor cavity (5) does not exceed 6 mT, preferably 5 mT.
- the outer magnetic shield (2) also encloses the lower pump body (6) comprising the roller bearing (7). The outer magnetic shield (2) is held in place by the clamping action of the jubilee clip (15) and a plate (16) attached to the base of the body (6).
- the channel (4) is used to direct room temperature air (c. 22 °C) across the outer surface of the pump envelope (3).
- the cooling air is pumped into the channel (4) through an inlet (11 ) at the base of the pump and exits through an outlet at the opposite end of the pump, e.g. the gaps (9) between the castellations (10) in the upper surface of the outer magnetic shield (2) which castellations, in use, engage a radially extending flange (8) of the pump envelope (3).
- This allows the temperature within the rotor cavity (5) to be maintained within a preferred range, and compensates for relatively the poor heat transfer properties of the pump envelope (3) and outer magnetic shield (2).
- the exemplified longitudinally extending circumferential channel (4) has a radial thickness (c) of at least 3 mm along its entire length.
- the tube-like outer magnetic shield (2) comprises two longitudinally extending sections (12, 13): to aid assembly more sections may be employed depending on the geometry of the specific vacuum pump. The sections are held in place by restraining means, which in this instance includes a jubilee clip (15) wrapped around a circumference of the outer magnetic shield (2) and a plate (16) attached to the lower pump body (6). The jubilee clip (15) is rated to a force of at least 350 N.
- the pump (1 ) and/or magnetic shield (2) may be fixed to a substantially immovable surface or object so that they will not move under the effect of the magnetic field when in use.
- the exemplified pump envelope (3) and outer magnetic shield (2) both comprise machined fully annealed mild-steel (e.g. 070M20, PD970-3). No further heat treatments were performed after machining, although the both were electroless nickel plated.
- the envelope (3) may be electroless nickel plated to prevent hydrogen permeation.
- the outer magnetic shield (2) benefits from the thin, robust and magnetic nature of the electroless nickel plate so that the shield segments (12, 13) can be mounted in close proximity to reduce the reluctance of their joints.
- the exemplified pump envelope (3) has a radial thickness (b) of at least 11 mm along its length.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Non-Positive Displacement Air Blowers (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1721771.2A GB2569648A (en) | 2017-12-22 | 2017-12-22 | Magnetic shield for a vacuum pump |
PCT/GB2018/053685 WO2019122869A1 (en) | 2017-12-22 | 2018-12-19 | Magnetic shield for a vacuum pump |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3728857A1 true EP3728857A1 (en) | 2020-10-28 |
Family
ID=61131662
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18829445.8A Pending EP3728857A1 (en) | 2017-12-22 | 2018-12-19 | Magnetic shield for a vacuum pump |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP3728857A1 (en) |
JP (1) | JP7305646B2 (en) |
GB (1) | GB2569648A (en) |
WO (1) | WO2019122869A1 (en) |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01190991A (en) * | 1988-01-26 | 1989-08-01 | Osaka Shinku Kiki Seisakusho:Kk | Vacuum pump |
JPH01216097A (en) * | 1988-02-22 | 1989-08-30 | Toshiba Corp | Magnetic shield type turbo molecular pump |
JP2897424B2 (en) * | 1990-11-30 | 1999-05-31 | ダイキン工業株式会社 | Vacuum pump |
DE10048695A1 (en) | 2000-09-30 | 2002-04-11 | Leybold Vakuum Gmbh | Side channel pump for conveying fluid gas mixtures has pump channel running in a spiral coil round rotor |
US6952268B2 (en) * | 2002-08-21 | 2005-10-04 | Honeywell International Inc. | Magnetic shield for a fiber optic gyroscope |
DE102013203421A1 (en) | 2013-02-28 | 2014-08-28 | Pfeiffer Vacuum Gmbh | vacuum pump |
DE102013203577A1 (en) | 2013-03-01 | 2014-09-04 | Pfeiffer Vacuum Gmbh | vacuum pump |
EP3034881B1 (en) * | 2014-12-18 | 2018-10-31 | Pfeiffer Vacuum GmbH | Vacuum pump |
CN205883692U (en) * | 2016-07-29 | 2017-01-11 | 中国原子能科学研究院 | Superconducting cyclotron vacuum apparatus |
-
2017
- 2017-12-22 GB GB1721771.2A patent/GB2569648A/en not_active Withdrawn
-
2018
- 2018-12-19 WO PCT/GB2018/053685 patent/WO2019122869A1/en unknown
- 2018-12-19 JP JP2020534181A patent/JP7305646B2/en active Active
- 2018-12-19 EP EP18829445.8A patent/EP3728857A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
GB201721771D0 (en) | 2018-02-07 |
GB2569648A (en) | 2019-06-26 |
WO2019122869A1 (en) | 2019-06-27 |
JP2021507174A (en) | 2021-02-22 |
JP7305646B2 (en) | 2023-07-10 |
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