Permanent magnet bearing and turbo molecular pump with permanent magnet bearing

Abstract

The utility model provides a permanent magnet bearing which comprises a plurality of inner magnetic rings, a plurality of outer magnetic rings and one or a plurality of partition plates, the inner magnetic rings and the outer magnetic rings are concentrically arranged, the partition plates are arranged between the inner magnetic rings and / or between the outer magnetic rings, and the magnetic poles of the magnetic rings on the two sides of each partition plate are the same. The utility model further provides a turbo molecular pump with the permanent magnet bearing. According to the permanent magnet bearing, the partition plate is arranged between the inner magnetic rings and / or the partition plate is arranged between the outer magnetic rings, and the magnetic poles of the magnetic rings on the two sides of the partition plate are the same. Therefore, the magnetic rings on the two sides of the partition plate do not have magnetic force or only have weak attraction force, and installation is convenient.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of permanent magnetic bearings, in particular to a kind of permanent magnetic bearings of easy assembly.

[0002] The utility model also relates to a kind of turbine molecular pump with permanent magnetic bearing. BACKGROUND

[0003] Turbine molecular pump is a kind of momentum transmission type vacuum pump, using high-speed rotating impeller to transmit momentum to gas molecules, so that gas produces directional flow and exhausts the vacuum pump, can produce clean vacuum in 10-3 To 10-10hPa range, because it is stable and reliable, and has good pumping efficiency under molecular flow state, has become the mainstream of clean high vacuum, ultra-high vacuum application field to obtain equipment, widely used in scientific instruments, industrial production equipment.

[0004] Figure 1 It is a typical cross-sectional view of conventional turbine molecular pump 10. Turbine molecular pump 10 usually includes cylindrical shell 11, base 12 connected with shell 11, rotor 21 coaxially arranged with shell 11, motor 13 coaxially arranged with rotor 21 and stator 14 extending axially inward from shell 11. Shell 11 provides a containing structure for turbine molecular pump 10, which also includes gas inlet connection port 15 penetrating the top of shell 11. Gas outlet 16 penetrates base 12 and is connected with a previous stage pump (not shown in the figure). Motor 13 drives rotor 21 to rotate around an axis. Rotor 21 can be supported in the shell by mechanical bearing 17 and by permanent magnetic bearing 20, adjusting nut 22 is used to adjust the axial position of the inner ring of permanent magnetic bearing. Mechanical bearing can also be replaced by magnetic suspension bearing. Rotor 21 includes multiple rows of rotor blades 19 extending axially outward from the central cylindrical part of the rotor at each level, and the central cylindrical part of the rotor is connected with motor 13. Stator 14 also includes multiple rows of blades 18 extending axially inward from shell 11 at each level. Multiple rows of stator blades 18 and multiple rows of rotor blades 19 are alternately arranged in axial layers. The "first stage" of the pump is defined as the first row of rotor blades 19 and the first row of stator blades 18 at the inlet end of the pump. Each row of rotor blades 18 and the corresponding row of stator blades 19 thereafter constitutes another stage, and the turbine molecular pump usually has 3 to 10 stages. In addition, 1-2 mixed stages (such as Holweck stage) can be included to achieve higher exhaust pressure and higher inlet pressure (not shown in the figure).

[0005] A great factor restricting the service life of turbine molecular pump is the bearing used, in order to improve its service life, a conventional method is to use a rolling ball bearing at one end for positioning, and a permanent magnetic bearing at the other end, such as CN220134260U. Permanent magnetic bearing has no physical contact, so it can obtain good service life.

[0006] Generally, the inner and outer rings of the permanent magnetic bearing are composed of multiple magnetic rings, and the inner and outer rings are arranged with the magnetic poles of the adjacent magnetic rings in opposite directions, such as CN220134260U. Figure 2 A schematic diagram (arrows are the directions of the magnetic poles) of the arrangement of the magnetic rings of the permanent magnetic bearing 20 in the molecular pump according to the prior art is shown. The permanent magnetic bearing 20 includes multiple outer ring magnetic rings 20a and multiple inner ring magnetic rings 20b arranged concentrically around the axis 23. The directions of the magnetic poles of the corresponding outer ring magnetic rings 20a and inner ring magnetic rings 20b are consistent. Each outer ring magnetic ring 20a is arranged with the magnetic poles of the magnetic rings of the adjacent stages in opposite directions, and needs to be pressed closely to each other to obtain better performance. Similarly, each inner ring magnetic ring 20b is arranged with the magnetic poles of the magnetic rings of the adjacent stages in opposite directions, and needs to be pressed closely to each other to obtain better performance.

[0007] In such a permanent magnetic bearing 20, there is a large repulsive force between the magnetic rings when installed in the same stage, and a large force needs to be applied to press them closely. However, the materials of the magnetic rings, including but not limited to neodymium iron boron and samarium cobalt, are relatively brittle, and applying a large force is easy to break them, making the installation more difficult. Practical new type content

[0008] Therefore, in view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a permanent magnetic bearing and a turbine molecular pump with the same, which can effectively solve the problem of difficult installation of the permanent magnetic bearing.

[0009] An aspect of the present application provides a permanent magnetic bearing, which includes multiple inner ring magnetic rings, multiple outer ring magnetic rings, and one or more partitions, the inner ring magnetic rings and the outer ring magnetic rings are arranged concentrically, wherein the partitions are arranged between the inner ring magnetic rings and / or the partitions are arranged between the outer ring magnetic rings, and the magnetic poles of the magnetic rings on both sides of each partition are the same.

[0010] Preferably, in the permanent magnetic bearing as described above, the inner ring magnetic rings and the partitions are arranged alternately, wherein the partitions have the same axial thickness as the inner ring magnetic rings; or the outer ring magnetic rings and the partitions are arranged alternately, wherein the partitions have the same axial thickness as the outer ring magnetic rings.

[0011] Preferably, in the permanent magnetic bearing as described above, the inner ring magnetic rings and the partitions are arranged alternately, wherein the axial thickness of the partitions is an odd multiple of the axial thickness of the inner ring magnetic rings; or the outer ring magnetic rings and the partitions are arranged alternately, wherein the axial thickness of the partitions is an odd multiple of the axial thickness of the outer ring magnetic rings.

[0012] Preferably, in the permanent magnetic bearing as described above, the inner ring magnetic rings and the partitions are arranged alternately; and the outer ring magnetic rings and the partitions are arranged alternately, wherein the axial thickness of the partitions between the inner ring magnetic rings is equal to the axial thickness of the partitions between the corresponding outer ring magnetic rings.

[0013] Preferably, in the permanent magnetic bearing as described above, the radial dimension of the partition plate is the same as the radial dimension of the inner magnetic ring and / or the outer magnetic ring.

[0014] Preferably, in the permanent magnetic bearing as described above, the difference between the radial dimension of the partition plate and the radial dimension of the inner magnetic ring and / or the outer magnetic ring is not more than 0.5 mm.

[0015] Preferably, in the permanent magnetic bearing as described above, the partition plate is a non-magnetic partition plate.

[0016] Preferably, in the permanent magnetic bearing as described above, the inner magnetic ring and / or the outer magnetic ring comprises a zinc plating coating or a nickel plating coating or an epoxy black coating.

[0017] An aspect of the present utility model provides a turbo molecular pump, which comprises the permanent magnetic bearing as described above.

[0018] According to the permanent magnetic bearing of the present utility model, the partition plate is arranged between the inner magnetic rings and / or the partition plate is arranged between the outer magnetic rings, and the magnetic poles of the magnetic rings on both sides of the partition plate are the same. Therefore, the magnetic rings on both sides of the partition plate have no magnetic force or only weak attractive force, which facilitates installation. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a simplified schematic view of the cross section of the prior art turbo molecular pump.

[0020] Figure 2 It is a schematic view of the magnetic ring arrangement of the prior art permanent magnetic bearing.

[0021] Figure 3 It is a schematic view of the first embodiment of the magnetic ring arrangement of the permanent magnetic bearing according to the present utility model.

[0022] Figure 4 It is a schematic view of the second embodiment of the magnetic ring arrangement of the permanent magnetic bearing according to the present utility model.

[0023] Figure 5 It is a schematic view of the third embodiment of the magnetic ring arrangement of the permanent magnetic bearing according to the present utility model.

[0024] Figure 6 It is a schematic view of the fourth embodiment of the magnetic ring arrangement of the permanent magnetic bearing according to the present utility model.

[0025] Figure 7 It is a schematic view of the fifth embodiment of the magnetic ring arrangement of the permanent magnetic bearing according to the present utility model. DETAILED DESCRIPTION

[0026] Figure 3This is a schematic diagram of a first embodiment of the magnetic ring arrangement of a permanent magnet bearing according to the present invention. The magnetic ring arrangement includes multiple outer magnetic rings 20a and multiple inner magnetic rings 20b concentrically arranged around an axis 23. The arrows in the diagram indicate the magnetic pole directions of each magnetic ring. Figure 2 Compared with the prior art shown, the present invention... Figure 3 In the illustrated embodiment, multiple outer magnetic rings 20a are replaced by outer partitions 20c. Thus, the outer magnetic rings 20a and outer partitions 20c are arranged alternately. The axial thickness of the outer partition 20c is the same as the axial thickness of the outer magnetic rings 20a. The magnetic poles of the outer magnetic rings 20a on both sides of each outer partition 20c are identical.

[0027] The outer partition 20c is made of a non-magnetic material, such as stainless steel, aluminum alloy, or rubber. The inner diameter of the outer partition 20c is 0–0.5 mm larger than the inner diameter of the outer magnetic ring 20a, and the outer diameter of the outer partition 20c is 0–0.5 mm smaller than the outer diameter of the magnetic ring. Optimal performance is achieved when the radial dimensions of the outer partition 20c and the outer magnetic ring 20a are the same. Considering the influence of machining accuracy, a difference of less than or equal to 0.5 mm is acceptable and will not affect assembly or the overall performance of the product.

[0028] exist Figure 3 In the embodiment shown, since the outer ring magnetic rings 20a on both sides of each outer partition 20c have the same magnetic poles and there is no magnetic force or only a weak attraction between them, it is easy to install.

[0029] In addition, considering that the magnetic ring itself has poor surface roughness due to processing issues, a coating (such as zinc plating, nickel plating, or epoxy black coating) can be added to the surface of the magnetic ring. This can prevent the magnetic ring from being corroded and also serve as a lubricant, facilitating its assembly.

[0030] Figure 4 This is a schematic diagram of a second embodiment of the magnetic ring arrangement of the permanent magnet bearing according to this utility model. Similar to... Figure 3 In the illustrated embodiment, multiple outer magnetic rings 20a are replaced by outer partitions 20c. The difference lies in that three consecutive outer magnetic rings 20a are replaced by outer partitions 20c. In other words, the outer magnetic rings 20a and outer partitions 20c are arranged alternately, and the axial thickness of the outer partition 20c is three times the axial thickness of the outer magnetic rings 20a. Similarly, the outer magnetic rings 20a on both sides of the outer partition 20c have the same magnetic poles and exert no magnetic force or only a weak attraction between them, thus facilitating installation.

[0031] Figure 4The illustrated embodiment is merely an example of this utility model. When the number of outer magnetic rings 20a is greater, the axial thickness of the outer partition plate 20c can be 5 times the axial thickness of the outer magnetic rings 20a, or other odd multiples, as long as the magnetic poles of the outer magnetic rings 20a on both sides of the outer partition plate 20c are the same. The characteristics of the outer partition plate 20c and the outer magnetic rings 20a in this embodiment can be the same as those in the first embodiment, and will not be repeated here.

[0032] Figure 5 This is a schematic diagram of a third embodiment of the magnetic ring arrangement of the permanent magnet bearing according to the present invention. Figure 5 The implementation shown is similar to Figure 3 The implementation shown differs in that Figure 5 In this embodiment, some of the inner magnetic rings 20b are replaced by inner partitions 20d, instead of the outer magnetic rings 20a. The inner magnetic rings 20b and inner partitions 20d are arranged alternately. The axial thickness of the inner partitions 20d is the same as the axial thickness of the inner magnetic rings 20b. The magnetic poles of the inner magnetic rings 20b on both sides of each inner partition 20d are identical, and there is no magnetic force or only a weak attraction between them, thus facilitating installation. The characteristics of the inner partitions 20d and inner magnetic rings 20b in this embodiment can be the same as those of the outer partitions 20c and outer magnetic rings 20a in the above embodiments, and will not be repeated here.

[0033] Figure 6 This is a schematic diagram of a fourth embodiment of the magnetic ring arrangement of the permanent magnet bearing according to the present invention. Figure 6 The implementation shown is similar to Figure 4 The implementation shown differs in that Figure 6 In this embodiment, a portion of the inner magnetic ring 20b is replaced by an inner partition 20d, instead of the outer magnetic ring 20a. The inner magnetic ring 20b and the inner partition 20d are arranged alternately. The axial thickness of the inner partition 20d is three times the axial thickness of the inner magnetic ring 20b. The inner magnetic rings 20b on both sides of each inner partition 20d have the same magnetic poles and exert no magnetic force or only a weak attraction on each other, thus facilitating installation. The characteristics of the inner partition 20d and inner magnetic ring 20b in this embodiment can be the same as those of the outer partition 20c and outer magnetic ring 20a in the embodiments described above, and will not be repeated here.

[0034] Figure 7 This is a schematic diagram of a fifth embodiment of the magnetic ring arrangement of the permanent magnet bearing according to the present invention. In this embodiment, part of the outer magnetic ring 20a and part of the inner magnetic ring 20b are simultaneously replaced by an outer partition plate 20c and an inner partition plate 20d. The axial thickness of the outer partition plate 20c and the inner partition plate 20d can be any size, but it is necessary to ensure that the thickness of the outer partition plate 20c and the inner partition plate 20d is the same. Figure 7As shown, the axial thickness of the outer spacer 20c and the axial thickness of the inner spacer 20d are the same and equal to the axial thickness of the outer ring magnetic ring 20a and the inner ring magnetic ring 20b. Similarly to Figure 4 and Figure 6 As shown in the embodiment, the axial thickness of the outer spacer 20c and the axial thickness of the inner spacer 20d can be 3 times the axial thickness of the outer ring magnetic ring 20a and the inner ring magnetic ring 20b. The axial thickness of the outer spacer 20c and the axial thickness of the inner spacer 20d can also be any multiple of the axial thickness of the outer ring magnetic ring 20a and the inner ring magnetic ring 20b. The characteristics of the outer spacer 20c, the inner spacer 20d, the outer ring magnetic ring 20a and the inner ring magnetic ring 20b in the present embodiment can be the same as those of the other embodiments as described above, and will not be repeated here.

[0035] In the embodiment shown in Figures 3-7 , the number of the outer ring magnetic ring 20a and the inner ring magnetic ring 20b is shown as 5. The present application is not limited to this, and the number of the outer ring magnetic ring 20a and the inner ring magnetic ring 20b is not limited, and it can be any number of three or more. When the number of the outer ring magnetic ring 20a and the inner ring magnetic ring 20b is three or more, the outer ring magnetic ring 20a and the inner ring magnetic ring 20b can be replaced by the outer spacer 20c and the inner spacer 20d according to the embodiment shown in Figures 3-7 , so that the magnetism of the outer ring magnetic ring 20a and / or the inner ring magnetic ring 20b on both sides of the outer spacer 20c and / or the inner spacer 20d is the same, that is, the purpose of the present application can be achieved.

[0036] In the embodiment shown in Figures 3-7 , part of the magnetic rings in the outer ring magnetic ring 20a and / or the inner ring magnetic ring 20b are replaced by the outer spacer 20c and the inner spacer 20d. In order to further improve the performance of the product, the outer ring magnetic ring 20a and / or the inner ring magnetic ring 20b with stronger magnetism can be used to reduce the impact of the decrease in the radial stiffness of the magnetic bearing caused by the addition of the outer spacer 20c and the inner spacer 20d. The magnetism of the outer ring magnetic ring 20a and / or the inner ring magnetic ring 20b can be selected according to actual needs, for example, the strength of the magnetic ring can be determined according to the simulation analysis result.

[0037] The present application also relates to a turbo molecular pump. Except that the permanent magnetic bearing adopts the magnetic ring arrangement according to the present application, other structures of the turbo molecular pump can adopt the structures in the prior art, for example, the structure shown in Figure 1 .

[0038] In the present specification, the specific features, mechanisms, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, a person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0039] The above merely illustrates the embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which is made according to the content of the present application and the drawings, is also included in the patent protection scope of the present application.

Claims

1. A permanent magnetic bearing, characterized by The permanent magnetic bearing comprises a plurality of inner magnetic rings, a plurality of outer magnetic rings and one or more spacers, the inner magnetic rings and the outer magnetic rings are arranged concentrically, wherein, the spacers are arranged between the inner magnetic rings, and / or the spacers are arranged between the outer magnetic rings, the magnetic poles of the magnetic rings on both sides of each spacer are the same.

2. The permanent magnetic bearing of claim 1, wherein, The inner magnetic rings and the spacers are arranged alternately, wherein the axial thickness of the spacers is the same as that of the inner magnetic rings; or The outer magnetic rings and the spacers are arranged alternately, wherein the axial thickness of the spacers is the same as that of the outer magnetic rings.

3. The permanent magnetic bearing of claim 1, wherein, The inner magnetic rings and the spacers are arranged alternately, wherein the axial thickness of the spacers is an odd multiple of the axial thickness of the inner magnetic rings; or The outer magnetic rings and the spacers are arranged alternately, wherein the axial thickness of the spacers is an odd multiple of the axial thickness of the outer magnetic rings.

4. The permanent magnetic bearing of claim 1, wherein, The inner magnetic rings and the spacers are arranged alternately; and the outer magnetic rings and the spacers are arranged alternately, wherein the axial thickness of the spacers between the inner magnetic rings is equal to the axial thickness of the spacers between the corresponding outer magnetic rings.

5. A magnetic bearing according to any one of claims 1-4, characterized in that The radial dimension of the spacers is the same as the radial dimension of the inner magnetic rings and / or the outer magnetic rings.

6. A magnetic bearing according to any one of claims 1-4, wherein The difference between the radial dimension of the spacers and the radial dimension of the inner magnetic rings and / or the outer magnetic rings is not more than 0.5 mm.

7. A magnetic bearing according to any one of claims 1 to 4, wherein The spacers are non-magnetic spacers.

8. The permanent magnetic bearing of any one of claims 1-4, wherein, The inner magnetic rings and / or the outer magnetic rings comprise a zinc-plated coating or a nickel-plated coating or an epoxy black coating.

9. A turbomolecular pump with permanent magnetic bearings, characterized in that The permanent magnetic bearing is the permanent magnetic bearing according to any one of claims 1-8.

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