Magnetic assemblies and vacuum pumps

Abstract

Preferably, the magnetic assembly for the rotor of a molecular drug vacuum pump comprises a first rotating magnet coupled to the rotor and rotating with the rotor; a stationary damper element positioned axially adjacent to the first rotating magnet and inducing eddy currents in the stationary damper element; a radially extending rotating yoke positioned axially adjacent to the first rotating magnet; a stationary coil configured to generate a magnetic field; and a stationary yoke coupled to the stationary coil and positioned immediately adjacent to the rotating yoke and inducing an axial magnetic force in the rotating yoke.

Description

Technical Field

[0001] The present invention relates to a magnetic assembly for a rotor of a vacuum pump, preferably a molecular drag pump. Further, the present invention relates to a vacuum pump provided with such a magnetic assembly. Further, the present invention relates to a method of assembling such a vacuum pump.

Background Art

[0002] A molecular drag pump such as a turbo molecular pump includes a housing having an inlet and an outlet. A pump chamber defines the housing, and a rotor assembly is rotatably supported within the pump chamber. The rotor assembly includes a rotor shaft, at least one pump element is coupled to the rotor shaft, and interacts with at least one stator element. The rotor assembly is rotated by an electric motor to carry a gaseous medium from the inlet to the outlet. In that regard, the rotor assembly can be supported by one or more radial bearings, and one or more of these radial bearings can be implemented as passive magnetic bearings with permanent magnets to support the rotor by its magnetic force.

[0003] Specifically, when using a passive magnetic bearing as a radial bearing, an axial bearing may be required to control the axial position of the rotor within the housing. This axial bearing may be implemented as an active axial magnetic bearing. In addition, a high-speed rotary vacuum pump requires a damping element to suppress unwanted vibrations or tumbling motions of the rotor. Implementing an axial bearing as well as a damper requires a large space. Further, in some embodiments, the axial bearing as well as the damper require a rotating permanent magnet. Implementing the required permanent magnets individually for each of the axial bearing and the damper increases the cost and complexity of the vacuum pump.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The objective of the present invention is to provide a compact, cost-effective magnetic assembly for a vacuum pump, particularly for the rotor of a molecular drug vacuum pump. [Means for solving the problem]

[0005] This objective is achieved by the magnetic assembly described in claim 1, the vacuum pump described in claim 9, and the method for assembling the vacuum pump described in claim 10.

[0006] According to the present invention, a magnetic assembly for a rotor, preferably a magnetic assembly for a rotor for a molecular drug vacuum pump, comprises a first rotating magnet coupled to the rotor of the vacuum pump and rotating together with the rotor. The first rotating magnet may have axial magnetization. The rotor defines an axial direction that coincides with the rotor's axis of rotation. The magnetic assembly comprises a stationary damper element positioned adjacent to the first rotating magnet in the axial direction, such that the first rotating magnet induces eddy currents in the stationary damper element. Thus, the combination of the first rotating magnet acting as a damper magnet and the stationary damper element constructs an eddy current damper (ECD) for reducing unwanted rotor movement.

[0007] Furthermore, a rotating yoke is positioned radially adjacent to the first rotating magnet in the axial direction. The magnetic assembly further comprises a stationary coil configured to generate a variable or dynamic magnetic field. The stationary coil is coupled to the stationary yoke, which is positioned immediately adjacent to the rotating yoke, and applies an axial magnetic force to the rotating yoke to control the axial position of the rotor. The variable magnetic field of the coil allows the magnetic force to be controlled to control the axial position of the rotor. In detail, the magnetic assembly, more preferably the magnetic axial bearing, comprises only a single stationary coil to reduce the complexity of the magnetic assembly, the required space, and consequently the cost of the magnetic assembly. By positioning the rotating yoke axially adjacent to the first rotating magnet, the first rotating magnet functions as a bias magnet, inducing magnetization in the rotating yoke, and the magnetic field of the stationary coil acts in cooperation with the bias magnet, i.e., the magnetic field of the first rotating magnet, via the stationary yoke. Thus, the first rotating magnet serves two purposes. Firstly, the first rotating magnet is used as a damper magnet to induce eddy currents in the stationary damper element in the ECD configuration. Secondly, the first rotating magnet functions as a bias magnet in the axial bearing of the magnetic assembly. Thus, the damper and axial bearing are integrated, and the number of permanent magnets required is reduced due to the two purposes of the first rotating magnet. Consequently, the cost of additional permanent magnets is saved, and at the same time, the required construction space is reduced due to the combination of damper and axial bearing.

[0008] Preferably, the stationary yoke surrounds the stationary coil, defining a gap into which the rotating yoke extends. Thus, a magnetic circuit is created by the stationary yoke, the rotating yoke, and the first rotating magnet. Simultaneously, a magnetic circuit is created by the stationary coil, the stationary yoke, the rotating yoke, and the first rotating magnet. Thus, with respect to the ECD and axial bearing, the magnetic field in either the stationary damper element or the rotating yoke is optimized / enhanced.

[0009] Preferably, the stationary yoke is constructed of one or more yoke elements, which are assembled together to form the stationary yoke. Thus, the stationary yoke assembly facilitates the interlocking elements of the magnetic assembly and the subsequent assembly of the stationary yoke by one or more yoke elements.

[0010] Preferably, the rotating yoke and / or stationary yoke are made of a magnetic material such as steel to enable the creation of a magnetic circuit.

[0011] Preferably, the stationary damper element is made of a conductive material to transmit eddy currents induced by the rotating magnet. More preferably, the stationary damper element is made of copper.

[0012] Preferably, the first rotating magnet has a first axial end and a second axial end on the opposite side, the stationary damper element is positioned immediately adjacent to the first axial end in the axial direction, and the rotating yoke is coupled to the second axial end. Thus, the stationary damper element and the rotating yoke are positioned at the axial end opposite to the first rotating magnet, and of course, the rotating yoke can be directly coupled to or in direct contact with the first rotating magnet (since the rotating yoke itself also rotates), while the stationary damper element is simply positioned immediately adjacent to the first rotating magnet and does not contact the first rotating magnet (since the stationary damper element does not rotate and contact must be prevented). This arrangement allows the rotating yoke and the stationary damper element to be positioned immediately adjacent to the first rotating magnet in order to strengthen the magnetic field at the position of the rotating yoke and / or the stationary damper element.

[0013] Preferably, the magnetic assembly comprises a second rotating magnet. The second rotating magnet may have axial magnetization, which is the same as that of the first rotating magnet. The second rotating magnet enhances the magnetic field within the magnetic assembly to further enhance the damping effect of the ECD realized by the stationary damper element and the efficiency of the axial bearing. As a result, the combination of the first and second rotating magnets functions together as a damper magnet that induces eddy currents in the stationary damper element, and simultaneously functions together as a bias magnet for axial support of the rotor. In this regard, preferably, the second rotating magnet is positioned axially adjacent to the first rotating magnet, but spaced apart to create a gap between the two rotating magnets. The stationary damper element may preferably extend into the gap between the first and second rotating magnets. In this configuration, the magnetic field at the stationary damper element is enhanced, and at the same time, the stationary damper element encounters an axially oriented magnetic field.

[0014] Preferably, the damper element is L-shaped or T-shaped and comprises an axial portion extending in the axial direction and a radial portion extending in the radial direction, wherein the axial portion is radially adjacent to the first and / or second rotating magnets, and the radial portion is positioned axially adjacent to the first and / or second rotating magnets, i.e., positioned in the gap created between the first and second rotating magnets. Thus, eddy currents are induced in the radial portion by the axial magnetic field, and the conductivity of the stationary damper element is enhanced by the axial portion, which increases the conductor, i.e., the cross-sectional area of ​​the stationary damper element.

[0015] In another embodiment, the present invention relates to a vacuum pump, more particularly to a molecular drag pump, the vacuum pump comprising a rotor assembly rotatably supported by one or more radial bearings and including the aforementioned magnetic assembly for axial support of the rotor and damping of rotor motion (i.e., non-axial rotation and vibration of the rotor). In this respect, the magnetic assembly implements an active axial bearing and an ECD, sharing at least one rotating magnet, thereby reducing the required construction space and the number of necessary parts. Thus, the cost and complexity of the vacuum pump can be reduced simultaneously.

[0016] Preferably, the vacuum pump is a turbomolecular pump, Holweck pump, Siegbahn pump, Gaede pump, etc.

[0017] Preferably, at least one of the one or more radial bearings is constructed as a passive magnetic bearing, and the other radial bearings can be constructed as roller bearings or passive magnetic bearings.

[0018] Preferably, the first rotating magnet and the rotating yoke, and more specifically the second rotating magnet, are also located within the common recess of the rotor. Thus, the first rotating magnet and / or the second rotating magnet, as well as the rotating yoke, can be mounted on the rotor so as to be located within the common recess.

[0019] Preferably, the first rotating magnet and / or the second rotating magnet, and the rotating yoke are fixed to the rotor by fastening elements such as nuts fixed to the rotor ends.

[0020] Preferably, the vacuum pump includes an axial position sensor for detecting the axial position of the rotor. More specifically, the surface of the fastening element is used as a detection surface by the axial position sensor, and the magnetic field generated by the stationary coil can be controlled by the axial position sensor to maintain the axial position of the rotor.

[0021] In another aspect of the present invention, a method for assembling a vacuum pump is provided. In this respect, the method is Steps to prepare housing elements, The steps include preparing the rotor and inserting the rotor at least partially into the housing element, Next, the process involves attaching a first rotating magnet to the rotor, attaching a stationary damper element to the housing element, attaching a rotating yoke to the rotor, attaching a stationary yoke to the housing element, and attaching a stationary coil to the housing element to create the aforementioned magnetic assembly. Includes.

[0022] Therefore, the interlocking elements of the magnetic assembly can be easily assembled within the vacuum pump during the subsequent assembly of the individual components of the magnetic assembly. It is not necessary to prepare a fully assembled rotor assembly to be inserted into the housing or housing element. Instead, a partially assembled rotor assembly is inserted into the housing element, and then the magnetic assembly is assembled within the housing element after the rotor insertion. In this regard, the housing element can be the housing of the vacuum pump, or just a part of the housing of the vacuum pump. In this regard, the housing element can contain one or more components of the vacuum pump, such as an electric motor. Alternatively, the housing element can contain only the magnetic assembly and be coupled to other housing elements that support the electric motor or stator of the vacuum pump.

[0023] Preferably, the first part of the stationary yoke, the rotating yoke, the first rotating magnet, the damper element, and the second rotating magnet are assembled in this order. This makes it possible to realize interlocking elements such as the damper element and the first rotating magnet, and the second rotating magnet. Subsequently, the second part of the stationary yoke can be assembled to create the stationary yoke surrounding the actuator coil. In this respect, the actuator coil can be implemented between each of the above steps and can be assembled independently of, for example, the rotating yoke, the first rotating magnet, the damper element, and / or the second rotating magnet.

[0024] Preferably, assemble the first part of the stationary yoke, the first rotating magnet, the damper element, the second rotating magnet, and the rotating yoke in this order.

[0025] Preferably, assemble the first part of the stationary yoke, the damper element, the first rotating magnet, and the rotating yoke in this order.

[0026] Preferably, assemble the first part of the stationary yoke, the rotating yoke, the first rotating magnet, and the damper element in this order.

[0027] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0028] [Figure 1] This is a vacuum pump according to the present invention. [Figure 2] This is a detailed view of the vacuum pump of FIG. 1. [Figure 3] This is another embodiment of the present invention. [Figure 4] This is another embodiment of the present invention. [Figure 5] This is another embodiment of the present invention.

Mode for Carrying Out the Invention

[0029] Figure 1 shows a vacuum pump, which is a turbomolecular pump, in this embodiment. The vacuum pump comprises a housing 10 having an inlet 12 and an outlet 14. The rotor 26 is supported by a first radial bearing 18, which is located within the housing 10 and constructed as a permanent magnet bearing, and a second radial bearing 16, which is similarly constructed as a permanent magnet bearing. The first radial bearing 18 comprises a plurality of magnet rings 22, 23 provided by permanent magnets. In this respect, the stationary magnet ring 23 of the first radial bearing 18 is attached to a trunnion 24 that extends into a recess in the rotor 26. The rotating magnet ring 22 is located on the inner surface of the recess, radially adjacent to the stationary magnet ring 23. With respect to the second radial bearing 16, the rotating magnet ring 21 is attached to the recess in the rotor 26, radially adjacent to the stationary magnet ring 20 coupled to the housing. In this respect, the stationary magnet ring 23 of the first radial bearing 18 repels each of the rotating magnet rings 22 of the first radial bearing 18, and similarly, the stationary magnet ring 20 of the second radial bearing 16 repels each of the rotating magnet rings 21 of the second radial bearing 16, thereby providing radial support for the rotor 26 within the housing 10.

[0030] Furthermore, the first radial bearing 18 and the second radial bearing 16 are equipped with emergency operation bearings 30 constructed as ball bearings. The rotor shaft 26 is driven by an electric motor 32. The rotor shaft 16 is fitted with a plurality of pump elements 34 constructed as vanes that interact with a stator element 36 coupled to the housing 10 of the vacuum pump, the stator element 36 being arranged alternately with the pump elements 34. In addition, the vacuum pump of Figure 1 is equipped with a Holweck stage 38 having a rotating cylinder 40 that interacts with a threaded stator 42 fixed to the housing. The rotation of the rotor shaft 26 carries the gaseous medium from the inlet 12 to the outlet 14 of the vacuum pump.

[0031] Referring to the lower part of the rotor 26 shown in Figure 1, Figure 2 shows the magnetic assembly 50 in more detail.

[0032] In this and the following description, “axial direction” coincides with the axis of rotation of the vacuum pump, and “radial direction” is perpendicular to the axial direction. Furthermore, identical or similar components are indicated by the same reference numerals.

[0033] The magnetic assembly 50 comprises a rotating yoke 52 coupled to the rotor shaft 26, and a first rotating magnet 54 and a second rotating magnet 56, both coupled to the rotor shaft 26. The first rotating magnet 54 and the second rotating magnet 56 may have axial magnetization, and preferably, the magnetizations of the first rotating magnet 54 and the second rotating magnet 56 are identical, i.e., they extend in the same direction. A gap 58 is created between the first rotating magnet 54 and the second rotating magnet 56, and a stationary damper element 60 is positioned within this gap 58. In this respect, the stationary damper element 60 in the embodiment of Figure 2 has a T-shaped structure comprising a radially extending portion 62 extending into the gap 58 and an axially extending portion 64 extending axially and positioned radially relative to the first rotating magnet 54 and the second rotating magnet 56. The stationary damper element 60 is constructed of a conductive material such as copper. The first rotating magnet 54 and the second rotating magnet 56 jointly function as damper magnets, providing a stationary damper element 60, an eddy current damper (ECD), in which eddy currents are induced in the stationary damper element 60 by the first rotating magnet 54 and the second rotating magnet 56, which counteract unwanted movements of the rotor shaft 26 to suppress precession, tumbling, and / or vibration of the rotor shaft 26. In this regard, the first rotating magnet 54 and the second rotating magnet 56 are constructed as annular permanent magnets surrounding the rotor shaft 26.

[0034] Furthermore, an active axial bearing is realized by the magnetic assembly 50. The rotating yoke 52 extends radially into the gap 66 created by the first stationary yoke element 68 and the second stationary yoke element 70. The first stationary yoke element 68 and the second stationary yoke element 70 create a stationary yoke surrounding the stationary coil 72. The stationary coil 72 creates a magnetic field which is applied to the rotating yoke 52 via the first stationary yoke element 68 and the second stationary yoke element 70. In this respect, the rotating yoke 52 is positioned immediately adjacent to the first rotating magnet 54 on the side facing the stationary damper element 60. Thus, magnetization is induced in the rotating yoke 52, which is made of magnetic material, by the first rotating magnet 54 and the second rotating magnet 56. Thus, the first rotating magnet 54 and the second rotating magnet jointly function as bias magnets for the axial bearing. The magnetization induced in the rotating yoke 52 interacts with the magnetic field created by the stationary coil 72. Therefore, the combination of the first rotating magnet 54 as a bias magnet and the stationary coil 72 makes it possible to control the axial position of the rotor shaft 26.

[0035] The stationary yokes 68 and 70, the stationary coil 72, and the rotating yoke 52, the first rotating magnet 54, and the second rotating magnet 56 generate the magnetic circuits 74 and 76 shown in Figure 2.

[0036] In this respect, by implementing the first rotating magnet 54 as a bias magnet, only a single stationary coil is required, thereby reducing the required construction space and system complexity. In addition, the first rotating magnet 54 functions as a bias magnet for the axial bearing and simultaneously as a magnet for the ECD created together with the stationary damper element 60. Therefore, by combining the damper and axial bearing, one permanent magnet can be omitted, avoiding associated costs. At the same time, the required construction space can be reduced.

[0037] As shown in Figure 2, the magnetic assembly comprises a stationary yoke constructed from a first stationary yoke element 68 and a second stationary yoke element 70, as well as interlocking elements such as a rotating yoke 52, a first rotating magnet 54, a second rotating magnet 56, and a radial portion 62 of a stationary damper element 60. To assemble such interlocking elements, each part of the magnetic assembly can be subsequently attached. Thus, the rotor shaft 26 has recesses 78 for accommodating the rotating yoke 52, the first rotating magnet 54, and the second rotating magnet 56. Thus, the rotating yoke 52, the first rotating magnet 54, and the second rotating magnet 56 can be sleeved onto the ends of the rotor shaft 26 and positioned in the recesses 68 of the rotor shaft 26. These parts can be constructed as nuts or screws and can be secured in place by fastening elements 80 that are fastened to the axial ends of the rotor shaft 26. Thus, the assembly of the embodiment in Figure 2 can be performed, for example, by first inserting the first stationary yoke element 68 together with the stationary coil 72. Subsequently, the rotating yoke 52 is placed on the shaft end of the rotor shaft 26 and positioned in the common recess 78 of the rotor shaft 26. Then, the first rotating magnet 54 is placed in the recess 78, followed by the stationary damper element 60 and the second rotating magnet 56. Next, all elements positioned in the recess 78 of the rotor shaft 26 are secured in place by fastening elements 80. In the final stage, the second stationary yoke element 70 can be assembled. Of course, the present invention is not limited to a specific assembly sequence, and further parts can be assembled in a different order. For example, the second stationary yoke element 70 can be assembled together with the stationary damper 60. Also, the stationary coil 72 can be assembled after the assembly of the rotating yoke 52 and / or the first rotating magnet 54.

[0038] The magnetic assembly further includes an axial position sensor 82, which detects the axial position of the rotor shaft 26. In this regard, the axial position sensor 82 can use the axial end face of the fastening element 80 as a reference plane to detect the axial position of the rotor shaft 26.

[0039] Figure 3 shows another embodiment of the magnetic assembly 50. In this aspect, the axial positions of the first rotating magnet 54 and the second rotating magnet 56 are swapped compared to the embodiment in Figure 2. As a result, the rotating yoke 52 is positioned at the axial end of the rotor shaft 26. Similarly, the assembly order is changed, with the first stationary yoke element 68 being assembled first, followed by the second rotating magnet 56 and the stationary damper element 60. Then, the first rotating magnet 54 and the rotating yoke 52 are assembled and secured with the fastening element 80. Finally, the second stationary yoke element 70 is assembled together with the stationary coil 72.

[0040] Figure 4 shows a magnetic assembly 50 comprising only the first rotating magnet 54. In this case, the stationary damper element 60 is L-shaped. Regarding assembly, first the first stationary yoke 68 is assembled. Then the rotating yoke 52, followed by the first rotating magnet 54, is assembled to the rotor shaft 26. After that, the stationary damper element 60 and the second stationary yoke element 70 are assembled.

[0041] Figure 5 shows the reversed configuration of the magnetic assembly 50 compared to the embodiment in Figure 4. Regarding assembly, first the first stationary yoke element 68 is assembled together with the stationary damper element 60. Then the first rotating magnet 54 and rotating yoke 52 can be assembled to the rotor shaft 26 and fixed in place with the fastening element 80. After that, the second stationary yoke element 70 is assembled together with the stationary coil 72.

[0042] Accordingly, the present invention provides a combination of an active axial bearing and an eddy current damper. This reduces the number of magnets required, resulting in a reduction in the required construction space and cost. In this regard, at least one permanent magnet of the magnet assembly according to the present invention simultaneously functions as a bias magnet for the active magnetic axial bearing and a damper magnet for the eddy current damper. [Explanation of Symbols]

[0043] 10 Housing 12 Entrance 14 Exit 16. Second radial bearing 18. First radial bearing 20 Stationary Magnet Rings 21 Rotating Magnetic Rings 22 Stationary Magnet Ring 23 Rotating Magnetic Rings 24 trunnions 26 rotor, rotor shaft 30 Emergency bearings 32 Electric motors 34 Pump elements 36 stater elements 38 Holweck section 40 cylinders 42 stata 50 Magnetic Assembly 5-rotation yoke 54 First Rotating Magnet 56. Second Rotating Magnet 58 gaps 60 Static damper elements 62 Radial section 64 Axial section 66 gaps 68 First stationary yoke element 70 Second stationary yoke element 7. Static coil 74 Magnetic Circuits 76 Magnetic Circuits 78 recesses 80 Fastening elements 82 Directional position sensor

Claims

1. Preferably a magnetic assembly for the rotor of a molecular drug vacuum pump, A first rotating magnet coupled to the rotor and rotating together with the rotor, A stationary damper element is positioned axially adjacent to the first rotating magnet, wherein the first rotating magnet functions as a damper magnet and induces eddy currents in the stationary damper element. A rotating yoke extending radially is positioned adjacent to the first rotating magnet in the axial direction, A stationary coil configured to generate a magnetic field, A stationary yoke coupled to the stationary coil and positioned immediately adjacent to the rotating yoke, which induces an axial magnetic force in the rotating yoke, Equipped with, The first rotating magnet is configured to function simultaneously as a bias magnet in a magnetic assembly.

2. The magnetic assembly according to claim 1, wherein the stationary yoke surrounds the stationary coil and has a gap, and the rotating yoke extends into the gap.

3. The magnetic assembly according to claim 1 or 2, wherein the rotating yoke and / or the stationary yoke are made of a magnetic material.

4. The magnetic assembly according to any one of claims 1 to 3, wherein the stationary damper element is made of a conductive material.

5. The magnetic assembly according to any one of claims 1 to 4, wherein the first rotating magnet comprises a first axial end and a second axial end on the opposite side, the stationary damper element is positioned immediately adjacent to the first axial end in the axial direction, and the rotating yoke is coupled to the second axial end.

6. The magnetic assembly according to any one of claims 1 to 5, comprising a second rotating magnet.

7. The magnetic assembly according to claim 6, wherein the second rotating magnet is positioned adjacent to the first rotating magnet in the axial direction at a distance that creates a gap between the first and second rotating magnets, and preferably the stationary damper element extends into the gap between the first and second rotating magnets.

8. The magnetic assembly according to any one of claims 1 to 7, wherein the damper element is L-shaped or T-shaped, comprising an axial portion extending in the axial direction and a radial portion extending in the radial direction, the axial portion being radially adjacent to the first rotating magnet and / or the second rotating magnet, and the radial portion being axially adjacent to the first rotating magnet and / or the second rotating magnet.

9. A vacuum pump, more specifically a molecular drug pump, comprising a rotor assembly rotatably supported by one or more radial bearings and comprising a magnetic assembly according to any one of claims 1 to 8 for axial support and damping.

10. A method for assembling a vacuum pump, Steps to prepare housing elements, The steps include preparing the rotor and inserting the rotor at least partially into the housing element, Next, the steps of attaching a first rotating magnet to the rotor, attaching a stationary damper element to the housing element, attaching a rotating yoke to the rotor, attaching a stationary yoke to the housing element, and attaching a stationary coil to the housing element to produce the magnetic assembly described in any one of claims 1 to 8, A method that includes this.

11. The method according to claim 10, wherein the first portion of the stationary yoke, the rotating yoke, the first rotating magnet, the damper element, and the second rotating magnet are assembled in this order.

12. The method according to claim 10, wherein the first portion of the stationary yoke, the first rotating magnet, the damper element, the second rotating magnet, and the rotating yoke are assembled in this order.

13. The method according to claim 10, wherein the first portion of the stationary yoke, the damper element, the first rotating magnet, and the rotating yoke are assembled in this order.

14. The method according to claim 10, wherein the first portion of the stationary yoke, the rotating yoke, the first rotating magnet, and the damper element are assembled in this order.

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