Vacuum pump with a magnet device comprising a coil wound on a coil carrier

Abstract

A vacuum pump (10) comprising: a housing (26); a rotor (12) arranged in the housing (26), the rotor (12) comprising a rotor shaft (32); a stator (14) arranged in the housing (26) and cooperatively associated with the rotor (12); and a magnet device (16) acting on the rotor (12), the magnet device (16) comprising a coil wound on a coil carrier (20); wherein the coil carrier (20) is adapted to seal a vacuum area (36) of the vacuum pump (10) against an external environment (38).

Description

[0001] VACUUM PUMP WITH A MAGNET DEVICE COMPRISING A COIL WOUND ON A COIL CARRIER

[0002] The present invention relates to a vacuum pump.

[0003] Turbomolecular pumps (TMPs) require fast rotations, particularly for the generation of high and ultra-high vacuum. In view of this, specific bearings are needed for the operation, particularly a reliably operation of the TMP.

[0004] A common concept in TMPs are hybrid-bearings, allowing for a robust and reliable bearing. Hybrid-bearings often combine a ceramic ball bearing on the prevacuum side with a permanent magnetic radial bearing on the high-vacuum side. Generally, the permanent magnetic bearing provides contact-free rotor stabilization, while the ceramic ball bearing protects the rotor from external shocks.

[0005] Another concept is provided using active magnetic bearings. Active magnetic bearings offer contactless support, preventing any contact between the rotor and the static components, e. g. the housing. Utilizing magnetic forces, the rotor remains levitated. This, for example makes active magnetic bearings ideal for applications requiring low wear, clean and lubricant-free conditions, and high speeds— such as in semiconductor manufacturing, coating technologies, and research. Often, the active magnetic bearing is provided on the pre-vacuum side. For emergency situations, such as a power loss in the active magnetic bearing, a mechanical emergency bearing could be provided, particularly on the prevacuum side. In addition, it is preferred that a permanent magnetic radial bearing is arranged on the high-vacuum side.

[0006] Although TMPs with active magnetic bearings have several advantages, including frictionless operation, no wear, and the ability to precisely control the rotor position, they also come with some disadvantages. For example, complex manufacturing might be required to assemble the magnetic bearings in the TMP. Furthermore, the integration of the magnetic bearing leads to a complex and expensive production processes, for example when implementing a necessary feed-through for the power supply for the bearing. Additionally, the thermal power of the magnetic bearing, particularly the coil, leads to issues, such as difficult thermal power dissipation.

[0007] Thus, it is an object of the present invention to provide a vacuum pump having an optimized bearing concept.

[0008] The object is solved by a vacuum pump according to claim 1.

[0009] The vacuum pump according to the invention preferably is a turbomolecular pump, more preferably a vertical turbomolecular pump. The vacuum pump comprises a housing and a rotor arranged in a housing. The rotor comprises a rotor shaft. Preferably, the rotor, for example the rotor shaft, is partly or completely magnetic. For example, the rotor can comprise iron or can be made of an iron alloy such as steel. The rotor is preferably driven by an electric motor. The vacuum pump further comprises a stator arranged in the housing and cooperatively associated with the rotor. Preferably, the housing is part of the stator. Additionally, the vacuum pump comprises a magnet device acting, preferably magnetically acting, on the rotor. The magnet device comprises a coil wound on a coil carrier. The coil carrier is adapted and / or arranged to seal a vacuum area, particularly the vacuum, of the vacuum pump against an external environment, preferably an atmosphere surrounding the vacuum area. The vacuum area preferably corresponds to the area in which the vacuum produced by the vacuum pump prevails. Particularly, the vacuum area of the vacuum pump corresponds to an area in the vacuum pump which has a lower pressure than the atmosphere. The vacuum area preferably corresponds to a chamber, more preferably a vacuum chamber, particularly within the housing. The coil carrier is adapted and / or arranged to seal a vacuum of the vacuum pump against a surrounding atmosphere.

[0010] It is preferred that the coil carrier is a one-piece, integral element. Alternatively, the coil carrier can, for example, comprise multiple elements to form a multi- piece coil carrier. If the coil carrier comprises multiple elements, the multiple elements are sealingly connected to each other. For example, the elements can comprise a sealing surface.

[0011] Preferably, the housing and the coil carrier form a casing enclosing the vacuum area, for example a chamber, particularly a vacuum chamber, of the vacuum pump. The chamber particularly corresponds to a chamber within the vacuum pump in which the vacuum produced by the vacuum pump prevails. Preferably, the casing seals the chamber against the external environment, more preferably the surrounding atmosphere.

[0012] Preferably, the coil carrier and / or the coil is arranged, for example concentrically, extending around, or surrounding, the rotor, particularly the rotor shaft. The carrier and / or the coil preferably surround, more preferably fully surround, the rotor, particularly the rotor shaft. Preferably windings of coil are arranged wound around rotor, particularly the rotor shaft. The coil carrier and / or the coil is arranged parallel to the rotor, particularly the rotor shaft. For example, the rotor, particularly the rotor shaft, is arranged inside the coil carrier and / or the coil. It is preferred that the rotor, particularly the rotor shaft, preferably completely, runs through the coil and / or the coil carrier.

[0013] Preferably, the coil is arranged in the atmosphere outside the vacuum area. It is preferred, that the coil is arranged outside the chamber, particularly the vacuum chamber. The coil is preferably arranged outside the casing. In view of this, it is particularly preferred that the coil is arranged completely in the external environment and / or completely outside the chamber and / or completely outside the casing.

[0014] Preferably, the coil carrier comprises, particularly consist, of one or more polymeric materials which may or may not be particulate or fibre reinforced. Preferred examples for the polymeric materials used for the coil carrier are: POM, PC, PET, PBT, PSU, PPS, PI, PEI, PAI and / or PEEK. The materials preferably balance the needed characteristics including workability, thermal resistance, sufficient strength, and stiffness, low water absorption and low gas permeability. Particularly, the material, preferably in the form of a polymer compound, may contain friction modifiers and / or temperature resistant enhancing additives.

[0015] Reinforcement, particularly of the material, may preferably be performed by glass, aramid- and / or carbon fibres. It is preferred that the coil carrier is non- electrically conductive or electrically conductive. Particularly, the coil carrier is non-magnetically conductive or magnetically conductive. The coil carrier is preferably PFAS-free, particularly does not comprise any material having PFAS. The coil carrier is preferably coated, for example with one or more of the following coatings: an electroless nickel-phosphorus coating and / or a low-outgassing polymeric coatings such as parylene.

[0016] Preferably, the magnet device comprises two or more coils, particularly in a differential coil arrangement, wound on the coil carrier. If multiple coils are wound on the coil carrier, it is preferred that the coil carrier is a multi-piece coil carrier, for example having one element per coil, whereby preferably each coil is wound on one of the elements.

[0017] Preferably, the vacuum pump comprises an active magnetic bearing supporting the rotor, wherein the coil of the magnet device corresponds to the actuator of the magnetic bearing. The actuator is preferably the active element of the magnetic bearing.

[0018] Preferably, the magnetic bearing is an axial magnetic bearing, preferably supporting the rotor axially levitating. It is preferred that the magnetic bearing is adapted to control the axial position of the rotor and / or adapted to carry an axial load of the rotor. Preferably, the rotor, particularly the rotor shaft, comprises a, preferably passive, magnetic counterpart for the coil, magnetically interacting with the coil. The counterpart is preferably a magnetic substrate for the coil. Particularly, the counterpart is magnetically influenced by the coil. Preferably the counterpart is an integral part of the rotor shaft and / or one or more elements connected to the rotor shaft. The counterpart is magnetic, preferably comprises iron.

[0019] Preferably, the counterpart protrudes radially from the rotor. For example, the counterpart can be connected radially to the rotor and / or the counterpart can be an integral radially protruding part of the rotor, such a shaft section protruding from a shaft base. If the counterpart is connected to the rotor shaft, the counterpart is preferably connected to the shaft in form-fit and / or force-fit manner, for example by means of a press fit.

[0020] Preferably, the vacuum pump comprises at least one sealing element arranged, preferably directly or indirectly, between the housing and the coil carrier and / or between a cover of the vacuum pump and the coil carrier. It is preferred that the at least one sealing element is connected directly or indirectly to each of the coil carrier, the housing, and the cover. Preferably the sealing element is an 0- ring. The at least one sealing element is preferably a radial and / or axial sealing element. Particularly, the housing, the coil carrier and the cover form a casing enclosing and preferably sealing the vacuum area, particularly a chamber, for example a vacuum chamber, of the vacuum pump. It is preferred that the cover connects the coil carrier to the housing in a form-fit and / or force-fit manner. Particularly, the cover is adapted and / or arranged to tension the sealing element, preferably tension a sealing element between the housing and the coil carrier and / or between the cover and the coil carrier.

[0021] Preferably, the coil carrier comprises at least one O-ring groove, particularly comprising an O-ring, to provide a sealing between the housing and the coil carrier and / or between the housing and the cover. It is preferred that the coil carrier comprise at least two O-ring grooves, particularly each comprising an Coring .

[0022] Preferably, the vacuum pump comprises a passive emergency bearing that axially supports the rotor. The passive emergency bearing is at least one of the following: a sliding contact bearing, a rolling-element bearing, a passive bearing, and a mechanical bearing. The passive emergency bearing is preferably adapted to support the rotor, particularly axially support the rotor in case of a malfunction, e. g. a power loss of the magnetic bearing.

[0023] Preferably, the coil carrier is arranged on a pre-vacuum side of the vacuum pump. Particularly, the magnetic bearing comprising the coil carrier is arranged on the pre-vacuum side of the vacuum pump. It is preferred that the coil carrier, more preferably the magnetic bearing, is arranged on one end of the rotor, particularly cooperatively interacting with said end of the rotor. Said end of the rotor is preferably an end of the rotor arranged on the pre-vacuum side of the vacuum pump and / or said end is preferably an end of the rotor arranged on a bottom side of the vacuum pump, particularly if the vacuum pump is a vertical vacuum pump. It is preferred that the coil carrier, more preferably the magnetic bearing, is arranged on one end of the vacuum pump, particularly on a bottom end of the vacuum pump if the vacuum pump is a vertical vacuum pump. Preferably, the passive emergency bearing is arranged on the pre-vacuum side of the vacuum pump and / or on said one end of the rotor and / or said one end of the vacuum pump.

[0024] Preferably, the vacuum pump comprises a radial bearing for the rotor, preferably a passive magnetic bearing. Particularly, the radial bearing is arranged on a high-vacuum side of the vacuum pump. It is preferred that the radial bearing is arranged on a second end, preferably opposite to said first, one end on which the magnetic bearing and / or the passive emergency bearing is arranged. In the following the present invention is described in more detail with reference to the accompanying drawings.

[0025] The figures show:

[0026] Figure 1 a schematic, sectional view of an embodiment of a vacuum pump according to the invention,

[0027] Figure 2 a detail view according to II. in Fig. 1,

[0028] Figure 3 a partial, schematic view showing of another embodiment of a vacuum pump according to the invention, and

[0029] Figure 4 a schematic, sectional view of another embodiment of a vacuum pump according to the invention.

[0030] Figure 1 shows an embodiment of a vacuum pump 10 according to the invention. The vacuum pump 10 is preferably a turbomolecular pump (TMP), more preferably a vertical TMP. Figure 2 shows a detail view according to II.

[0031] The vacuum pump 10 comprises a housing 26 and a rotor 12 arranged in the housing 26. The rotor 12 comprises a rotor shaft 32. The rotor shaft 32 supports a plurality of rotor blades 30 arranged around the rotor shaft 32.

[0032] Further, the vacuum pump 10 comprises a stator 14 arranged in the housing 26. The stator 14 comprises a plurality of stator blades 28. The rotor blades 30 are positioned between stator blades 28. As such, the stator 14, particularly the plurality of stator blades 28 is cooperatively associated with the rotor 12, particularly the plurality of rotor blades 30. Fluid, particularly gas, inflows at a first end 52, for example a top end, of the vacuum pump, particularly in an area of the high-vacuum side 50 of the vacuum pump 10.

[0033] Particularly, on a pre-vacuum side 54 of the vacuum pump 10 and / or a bottom end 56 of the vacuum pump 10 a magnet device 16 is arranged. The magnet device 16 comprises a coil 18 wound on a coil carrier 20. The coil carrier 20 and the coil 18 is arranged concentrically surrounding the rotor shaft 32.

[0034] The coil 18 of the magnetic device 16 magnetically influences the rotor 12, for example the magnetically conductive rotor shaft 32.

[0035] The magnetic device 16 in combination with the magnetic conductivity of the rotor 12, particularly the rotor shaft 32, for example in combination with a magnetic part of the rotor 12, provides an active magnetic bearing 19 supporting the rotor 12. Preferably, the magnetic bearing 19 is an axial magnetic bearing, particularly supporting the rotor 12 through axial levitation. The magnetic conductivity of the rotor 12, for example the rotor shaft 32, provides the magnetic counterpart for the coil 18 acting as the actuator of the magnetic bearing 19.

[0036] The coil carrier 20 is arranged between the housing 26 and a cover 24 closing off the vacuum pump 10 at the bottom end 56. An O-ring 22 in an O-ring groove 23 of the coil carrier 20 provides a sealing between the coil carrier 20 and the housing 26 and another O-ring 22 in an O-ring groove 23 of the coil carrier 20 provides a sealing between the coil carrier 20 and the cover 24 (cf. Fig. 2). Preferably, the coil carrier 20 is arranged in a press-fit between the housing 26 and the cover 24, for example tensioned by the cover 24. This press-fit particularly provides a contact pressure (indicated by arrows 34, cf. Fig. 2) for the O- rings 22. As such, the coil carrier 20 is adapted to seal a vacuum area 36 of the vacuum pump 10 against a surrounding environment 38, for example the ambient atmosphere. Preferably, a vacuum is present in the vacuum area 36. For example, the vacuum area 36 corresponds to a chamber, particularly a vacuum chamber, of the vacuum pump 10.

[0037] The housing 26 and the coil carrier 20 and preferably the cover 24 form a casing enclosing the vacuum area 36, for example the chamber, particularly the vacuum chamber, of the vacuum pump 10. This casing preferably seals the vacuum area 36, particularly the chamber against the surrounding environment 38, more preferably the ambient atmosphere.

[0038] The coil 18 of the magnetic device 16 is arranged outside the vacuum area 36, particularly the chamber.

[0039] This arrangement of the coil 18 results in the advantage that thermal power of the coil 18 can be easily dissipated and / or that it is not necessary to implement a feed-through in the vacuum pump 10, particularly the housing 26.

[0040] Figure 3 shows another embodiment of a vacuum pump 10 according to the invention, whereby the embodiment is based on the embodiment shown in Figure 2 and preferably can be implemented correspondingly in accordance with the embodiment of Figure 1.

[0041] The magnetic device 16 of Figure 3 corresponds to the magnetic device 16 of Figure 2. In contrast to Figure 2, the cover 24 of Figure 3 comprises a step 25, preferably integrally formed with the cover 24, adapted to provide a form-fitting fixation of the coil carrier 20.

[0042] In contrast to the embodiment of Figure 1, a magnetic element 33 radially connected, for example by a form-fit and / or a press-fit to the rotor shaft 32 functions as the counterpart for the coil 18 to implement the magnetic bearing 19, in Figure 3. Particularly the coil 18 magnetically influences the magnetic element 33 to implement an axial magnetic bearing, preferably supporting the rotor 12 axially levitating.

[0043] As indicated by an axis of symmetry (line 21), the embodiment of Figure 3, particularly the magnetic device 16 and / or the rotor shaft 32 comprising the magnetic element 33, is symmetrical, preferably axial symmetrical.

[0044] Figure 4 shows another embodiment of a vacuum pump 10 according to the invention. The embodiment of Figure 4 mostly corresponds to the embodiment of Figure 1 having the magnetic bearing 19 as well as the implementation of the cover 24 of Figure 3.

[0045] Further, the vacuum pump 10 of Figure 4 comprises a passive emergency bearing 48, preferably axially supporting the rotor 12, arranged between the rotor shaft 32 and the housing 26. In the shown embodiment the passive emergency bearing 48 corresponds to a rolling-element bearing. The passive emergency bearing 48 is preferably adapted to support the rotor 12 in case of a malfunction, e. g. a power loss of the magnetic bearing 19.

[0046] In addition, the vacuum pump 10 of Figure 4 comprises a radial bearing 40 for the rotor 12. The radial bearing 40 shown in the embodiment of Figure 4 is a passive magnetic bearing having a magnetic element 42, for example a permanent magnet, connected via a supporting structure 27 to the housing 26 and opposite, cooperatively associated a magnetic element 44, for example a permanent magnet, connected radially to the rotor shaft 32.

Claims

CLAIMS1. A vacuum pump (10), particularly a turbomolecular pump, comprising: a housing (26); a rotor (12) arranged in the housing (26), the rotor (12) comprising a rotor shaft (32); a stator (14) arranged in the housing (26) and cooperatively associated with the rotor (12); and a magnet device (16) acting on the rotor (12), the magnet device (16) comprising a coil wound on a coil carrier (20); wherein the coil carrier (20) is adapted to seal a vacuum area (36) of the vacuum pump (10) against an external environment (38).

2. The vacuum pump (10) according to claim 1, wherein the housing (26) and the coil carrier (20) form a casing enclosing a chamber, particularly a vacuum chamber, of the vacuum pump (10).

3. The vacuum pump (10) according to claim 1 or 2, wherein the coil carrier and / or the coil (18) is arranged surrounding, preferably concentrically surrounding, the rotor shaft (32).

4. The vacuum pump (10) according to any one of claims 1-3, wherein the coil (18) is arranged in the external environment (38), preferably the atmosphere, outside the vacuum area (36).

5. The vacuum pump (10) according to any one of claims 1-4, wherein the coil carrier (20) comprises, particularly consist of, of one or more of the following materials POM, PC, PET, PBT, PSU, PPS, PI, PEI, PAI and PEEK.

6. The vacuum pump (10) according to any one of claims 1-5, wherein the magnet device (16) comprises at least two coils (18), preferably in a differential coil arrangement, wound on the coil carrier (20).

7. The vacuum pump (10) according to any one of claims 1-6, wherein the vacuum pump (10) comprises an active magnetic bearing (19) supporting the rotor (12), wherein the coil (18) of the magnet device corresponds to the actuator of the magnetic bearing (19).

8. The vacuum pump (10) according to claim 7, wherein the magnetic bearing (19) is an axial magnetic bearing (19).

9. The vacuum pump (10) according to any one of claims 1 to 8, wherein the rotor (12) comprises a, preferably passive, magnetic counterpart for the coil (18), magnetically interacting with the coil (18).

10. The vacuum pump (10) according to claim 9, wherein the counterpart protrudes radially from the rotor (12).

11. The vacuum pump (10) according to any one of claims 1 to 10, wherein the vacuum pump (10) comprises at least one sealing element, particularly an O- ring, arranged between the housing (26) and the coil carrier and / or between a cover (24) of the vacuum pump (10) and the coil carrier (20).

12. The vacuum pump (10) according to any one of claims 1 to 11, wherein the vacuum pump (10) comprises a passive emergency bearing that axially supports the rotor (12).

13. The vacuum pump (10) according to any one of claims 1 to 12, wherein the coil carrier (20) is arranged on a pre-vacuum side (54) of the vacuum pump14. The vacuum pump (10) according to any one of claims 1 to 13, wherein the vacuum pump (10) comprises a radial bearing (40) for the rotor (12), preferably a passive magnetic bearing.

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