Magnetic suspension bearing and magnetic suspension rotating machine

Abstract

The invention provides a magnetic suspension bearing and a magnetic suspension rotating machine, the magnetic suspension bearing comprises a first axial stator, a second axial stator and a thrust disc, in the axial direction of the magnetic suspension bearing, the thrust disc is arranged between the first axial stator and the second axial stator, and the thrust disc is arranged between the first axial stator and the second axial stator; a first thrust disc ventilation hole is formed in the thrust disc in a penetrating mode from one axial end face to the other axial end face of the thrust disc, the first axial stator comprises a first radial outer side portion and a first radial inner side portion, and one end, located on the other axial end face of the thrust disc, of the first thrust disc ventilation hole is located between the second radial inner side portion of the second axial stator and the rotor. One end, located on one axial end face of the thrust disc, of the first thrust disc ventilation hole is opposite to the position of the first coil groove in the axial direction, and the first thrust disc ventilation hole is not opposite to the magnetic pole position of the first axial stator. According to the magnetic suspension bearing, heat dissipation and cooling of the magnetic suspension bearing are improved, meanwhile, the influence on a magnetic suspension magnetic circuit can be avoided, and enough magnetic suspension supporting force is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic suspension bearings, and in particular to a magnetic suspension bearing and a magnetic suspension rotating machine. Background Art

[0002] At present, the heat dissipation of magnetic levitation blowers is mainly external cooling equipment, usually external cooling fans, water cooling systems and heat exchangers, etc., which have high equipment maintenance costs, complex structural systems, and increased safety hazards. Or in the form of negative pressure, air is sucked from the blower to guide the heat out, which cannot more effectively achieve the heat dissipation of internal components, especially the heat dissipation of axial magnetic bearings is not sufficient, affecting the stable operation of the magnetic levitation air compressor.

[0003] The axial magnetic bearing realizes the axial movement of the rotating shaft, and an axial force-bearing component is indispensable on the rotating shaft, which is the thrust plate. The axial magnetic bearing and the thrust plate are made of pure iron solid structure, which has relatively large self-loss, general thermal conductivity and small space. If it is not effectively cooled, it will generate serious heat. Usually, in order to avoid excessive temperature rise of the axial magnetic bearing, forced air cooling is often applied externally to dissipate the heat of the magnetic bearing. The cooling air is input from the outside and dissipates the heat of the axial magnetic bearing through the gap between the bearing stator and the thrust plate, but the heat dissipation efficiency is not high.

[0004] Since the magnetic suspension bearing inside the rotating machine in the prior art has technical problems such as poor cooling and heat dissipation effect, the present invention studies and designs a magnetic suspension bearing and a magnetic suspension rotating machine. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of poor cooling and heat dissipation effect of the magnetic suspension bearing inside the rotating machine in the prior art, thereby providing a magnetic suspension bearing and a magnetic suspension rotating machine.

[0006] In order to solve the above problems, the present invention provides a magnetic bearing, which includes:

[0007] Axial stator 1, axial stator 2 and thrust plate, in the axial direction of the magnetic bearing, the thrust plate is arranged between the axial stator 1 and the axial stator 2, a first thrust plate ventilation hole is arranged on the thrust plate from its axial end face 1 to the other axial end face, the axial stator 1 includes a radial outer portion 1 and a radial inner portion 1, the radial outer portion 1 and the radial inner portion 1 are arranged at intervals in the radial direction of the axial stator 1, and a coil slot 1 is formed between the two, and a coil 1 is arranged in the coil slot 1;

[0008] The axial stator 2 includes a radial outer portion 2 and a radial inner portion 2,

[0009] One end of the first thrust plate ventilation hole located on the other axial end face of the thrust plate is located between the radial inner side 2 of the axial stator 2 and the rotor, and one end of the first thrust plate ventilation hole located on the one axial end face of the thrust plate is opposite to the position of the coil slot 1 in the axial direction, and the first thrust plate ventilation hole is not opposite to the magnetic pole position of the axial stator 1.

[0010] In some embodiments,

[0011] It also includes a pressure plate 1, the pressure plate 1 is located between the axial stator 1 and the thrust plate, and an axial end surface of the pressure plate 1 is connected to the radial outer side portion 1 of the axial stator 1, and the other axial end surface of the pressure plate 1 is opposite to the thrust plate;

[0012] The magnetic pole position of the axial stator 1 includes a portion of the pressure plate 1 opposite to the thrust disk, and a portion of the radial inner portion 1 opposite to the thrust disk, a first gap is provided between the pressure plate 1 and the radial inner portion 1, the first thrust disk ventilation hole is opposite to the first gap in the axial direction, and a radial dimension of the first gap is greater than or equal to a radial dimension of an end of the first thrust disk ventilation hole opposite to the coil slot 1.

[0013] In some embodiments,

[0014] In any radial cross section of the thrust plate, the cross-sectional area of ​​the magnetic path flow position of the axial stator 1 = the radial cross-sectional area of ​​the thrust plate and the corresponding part of the axial stator 1 - the cross-sectional area of ​​the ventilation hole of the first thrust plate ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 1.

[0015] In some embodiments,

[0016] Inside the coil slot 1, a second gap is provided between the radial inner side of the coil 1 and the radial inner portion 1, forming a first gas flow path.

[0017] The axial stator 1 also includes an axial outer portion 1, which is arranged in the axial direction of the magnetic bearing relative to the coil 1 and away from the thrust plate. Inside the coil slot 1, there is also a third gap between the axial outer portion 1 and the coil 1, forming a bearing stator ventilation slot 1;

[0018] A bearing stator ventilation hole is provided on the axial outer side portion 1 of the axial stator 1. The bearing stator ventilation hole 1 penetrates from one axial end surface of the axial outer side portion 1 to the other axial end surface so as to be connected with the bearing stator ventilation groove 1, and further connected to the first thrust plate ventilation hole through the first gas flow path.

[0019] In some embodiments,

[0020] Along the axial direction of the thrust plate, the first thrust plate ventilation hole is an inclined hole structure whose extension direction is not parallel to the axis of the thrust plate, and the rotation direction of the thrust plate is toward a first rotation direction when observing from the axial end face of the air inlet side of the thrust plate toward the axial end face of the air outlet side. The extension direction of the first thrust plate ventilation hole from the axial end face of the air inlet side of the thrust plate toward the axial end face of the air outlet side is toward a second rotation direction, and the second rotation direction is opposite to the first rotation direction.

[0021] In some embodiments,

[0022] There are multiple ventilation holes in the first thrust plate, and the multiple ventilation holes in the first thrust plate are arranged at intervals along the circumferential direction of the thrust plate. An extension direction of each ventilation hole in the first thrust plate from an axial end face on the air inlet side of the thrust plate toward an axial end face on the air outlet side is toward a second rotation direction, which is opposite to the first rotation direction of the thrust plate.

[0023] In some embodiments,

[0024] The thrust plate is provided with a second thrust plate ventilation hole extending from the other axial end surface to the one axial end surface thereof, and the second thrust plate ventilation hole is offset from the first thrust plate ventilation hole and is not connected;

[0025] The radial outer portion 2 and the radial inner portion 2 are spaced apart in the radial direction of the axial stator 2, and a coil slot 2 is formed therebetween, a coil 2 is arranged in the coil slot 2, an end of the second thrust plate ventilation hole located on the one axial end face of the thrust plate is located between the radial inner portion 1 of the axial stator 1 and the rotor, an end of the second thrust plate ventilation hole located on the other axial end face of the thrust plate is opposite to the position of the coil slot 2 in the axial direction, and the second thrust plate ventilation hole is not opposite to the magnetic pole position of the axial stator 2.

[0026] In some embodiments,

[0027] It also includes a second pressure plate, the second pressure plate is located between the second axial stator and the thrust plate, and one axial end surface of the second pressure plate is connected to the second radial outer side of the second axial stator, and the other axial end surface of the second pressure plate is opposite to the thrust plate;

[0028] The magnetic pole position of the axial stator 2 includes the portion of the pressure plate 2 opposite to the thrust plate, and the portion of the radial inner portion 2 opposite to the thrust plate, a fourth gap is provided between the pressure plate 2 and the radial inner portion 2, the second thrust plate ventilation hole is opposite to the fourth gap in the axial direction, and a radial dimension of the fourth gap is greater than or equal to a radial dimension of an end of the second thrust plate ventilation hole opposite to the coil slot 2.

[0029] In some embodiments,

[0030] In each radial cross section of the thrust plate, the cross-sectional area of ​​the magnetic path flow position of the axial stator 2 = the radial cross-sectional area of ​​the thrust plate and the corresponding part of the axial stator 2 - the cross-sectional area of ​​the ventilation hole of the second thrust plate ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 2.

[0031] In some embodiments,

[0032] Inside the coil slot 2, a fifth gap is provided between the radial inner side of the coil 2 and the radial inner portion 2 to form a second gas flow path.

[0033] The second axial stator further comprises a second axial outer portion, which is arranged in the axial direction of the magnetic bearing relative to the second coil and away from the thrust plate, and inside the second coil slot, there is also a sixth gap between the second axial outer portion and the second coil, forming a second bearing stator ventilation slot;

[0034] A bearing stator ventilation hole 2 is provided on the axial outer side 2 of the axial stator 2. The bearing stator ventilation hole 2 penetrates from one axial end surface of the axial outer side 2 to the other axial end surface to be connected with the bearing stator ventilation groove 2, and is further connected to the second thrust plate ventilation hole through the second gas flow path.

[0035] In some embodiments,

[0036] Along the axial direction of the thrust plate, the second thrust plate ventilation hole is an inclined hole structure whose extension direction is not parallel to the axis of the thrust plate, and the rotation direction of the thrust plate is toward the third rotation direction when observing from the axial end face of the air inlet side of the thrust plate toward the axial end face of the air outlet side. The extension direction of the second thrust plate ventilation hole from the axial end face of the air inlet side of the thrust plate toward the axial end face of the air outlet side is toward the fourth rotation direction, and the fourth rotation direction is opposite to the third rotation direction.

[0037] In some embodiments,

[0038] There are multiple ventilation holes of the second thrust plate, and the multiple ventilation holes of the second thrust plate are arranged at intervals along the circumferential direction of the thrust plate. An extension direction of each ventilation hole of the second thrust plate from the axial end face on the air inlet side of the thrust plate toward the axial end face on the air outlet side is toward the fourth rotation direction, which is opposite to the third rotation direction of the thrust plate.

[0039] The present invention also provides a magnetic suspension rotating machine, which includes the above-mentioned magnetic suspension bearing.

[0040] The magnetic suspension bearing and magnetic suspension rotating machine provided by the present invention have the following beneficial effects:

[0041] 1. The present invention realizes active air suction and heat exchange through high rotation speed by opening the first and / or second thrust plate ventilation holes on the thrust plate, increases the gas flow rate, accelerates the cooling of the axial magnetic bearing, actively cools the thrust plate itself and increases the cooling flow rate to accelerate the heat dissipation of the axial coil, improves the cooling and heat dissipation effect of the magnetic suspension bearing, and makes the end of the first thrust plate ventilation hole opposite to the coil slot one not opposite to the magnetic pole position of the axial stator one (one end of the second thrust plate ventilation hole is not opposite to the magnetic pole position of the axial stator two), so that the end face of the thrust plate is not punched at the position facing the magnetic pole, so that the cooling air cannot directly reach the magnetic pole gap position, which can effectively avoid the influence of the cooling gas and the opening on the magnetic furnace structure, thereby avoiding the magnetic suspension axial support. The force is insufficient, and the heat dissipation and cooling of the magnetic suspension bearing can be improved while avoiding the influence on the magnetic suspension magnetic circuit, ensuring sufficient magnetic suspension supporting force, and effectively reducing the influence of the gas force on the axial force; the present invention also preferably extends the first thrust plate ventilation hole from one end of the thrust plate located between the axial stator and the rotor to the other end of the thrust plate opposite to the coil slot one, which can cool the coil inside the stator, and the aperture size of the end opposite to the coil slot one is ≤ the radial spacing between the upper and lower magnetic poles of the axial stator, which can make the thrust plate ventilation hole further effectively avoid the magnetic pole position, further avoid the influence on the magnetic circuit, and the thrust plate ventilation hole is connected with the ventilation paths at both ends without obstruction, and the airflow resistance at both ends of the thrust plate is small and the fluidity is good.

[0042] 2. The present invention further sets the relationship in any radial cross section of the thrust disk: the cross-sectional area of ​​the magnetic path flow position of the axial stator 1 = the radial cross-sectional area of ​​the thrust disk and the corresponding part of the axial stator 1 - the cross-sectional area of ​​the ventilation hole of the first thrust disk ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 1, so that the other magnetic path parts on the thrust disk that are different from the magnetic pole position will not appear magnetic field saturation before the magnetic pole position, thereby ensuring the formation of a normal magnetic flux circuit and ensuring the continuous and effective provision of the magnetic suspension support force; the present invention further sets the ventilation hole of the thrust disk to extend from one axial end face to the other axial end face in the direction toward The second rotation direction is opposite to the first rotation direction (the rotation direction of the thrust plate). When the rotor drives the thrust plate to rotate at a high speed, negative pressure is generated to suck out the hot air at one end and discharge it to the outside, thereby increasing the gas flow rate, realizing active ventilation and heat exchange of the thrust plate itself, accelerating the gas flow, saving energy consumption, improving the heat dissipation performance and improving the energy efficiency; at the same time, in conjunction with the bearing stator ventilation holes and ventilation grooves (multiple gas flow paths) in the axial stator coil slots, the gas flow in the axial stator coil slot cavity can be further accelerated, thereby realizing effective autonomous heat dissipation of the axial coil and the thrust plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a longitudinal sectional view of embodiment 1 of the magnetic bearing of the present invention;

[0044] Figure 2 yes Figure 1 The plan view of the thrust plate structure in FIG. 1 (thrust plate ventilation hole with left-handed inclined hole);

[0045] Figure 3 is a longitudinal sectional view of a second embodiment of the magnetic bearing of the present invention;

[0046] Figure 4 yes Figure 3 The planar structural diagram of the thrust plate structure in FIG. 1 (thrust plate ventilation hole with right-handed inclined hole);

[0047] Figure 5 It is a three-dimensional structural diagram of the axial stator 1 of the present invention.

[0048] The reference numerals are:

[0049] 1. Axial stator 1; 11. Radial outer part 1; 12. Radial inner part 1; 13. Coil slot 1; 14. Axial outer part 1; 2. Axial stator 2; 21. Radial outer part 2; 22. Radial inner part 2; 23. Coil slot 2; 24. Axial outer part 2; 3. Thrust plate; 4. Pressure plate 1; 4', Pressure plate 2; 5. Coil 1; 5', Coil 2; 6. Rotor;

[0050] 01. First thrust plate ventilation hole; 02. Second thrust plate ventilation hole; 03. Bearing stator ventilation hole one; 03', bearing stator ventilation hole two; 04. Bearing stator ventilation slot one; 04', bearing stator ventilation slot two; 05. First gap; 06. First gas flow path; 07. Fourth gap; 08. Second gas flow path. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0053] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0054] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0055] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0056] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0057] like Figure 1-5 As shown, the present invention provides a magnetic bearing, which includes:

[0058] An axial stator 1, an axial stator 2 and a thrust plate 3. In the axial direction of the magnetic bearing, the thrust plate 3 is arranged between the axial stator 1 and the axial stator 2. A first thrust plate ventilation hole 01 is provided on the thrust plate 3 from one axial end face to the other axial end face. The axial stator 1 includes a radial outer portion 11 and a radial inner portion 12. The radial outer portion 11 and the radial inner portion 12 are spaced apart in the radial direction of the axial stator 1, and a coil slot 13 is formed therebetween. A coil 5 is arranged in the coil slot 13. The axial stator 2 includes a radial outer portion 21 and a radial inner portion 22.

[0059] One end of the first thrust plate ventilation hole 01 located on the other axial end face of the thrust plate 3 is located between the radial inner portion 22 of the axial stator 2 and the rotor 6, and one end of the first thrust plate ventilation hole 01 located on the one axial end face of the thrust plate 3 is opposite to the position of the coil slot 13 in the axial direction, and the first thrust plate ventilation hole 01 is not opposite to the magnetic pole position of the axial stator 1.

[0060] The present invention realizes its own active air suction heat exchange through high rotation speed through the first thrust plate ventilation hole opened on the thrust plate, increases the gas flow rate introduced, and accelerates the cooling of the axial magnetic bearing. It can actively cool the thrust plate itself and increase the cooling flow rate to accelerate the heat dissipation of the axial coil, thereby improving the cooling and heat dissipation effect of the magnetic suspension bearing. In addition, the end of the first thrust plate ventilation hole opposite to the coil slot one is not opposite to the magnetic pole position of the axial stator one, so that the thrust plate end face is not punched at the position facing the magnetic pole, so that the cooling air cannot directly reach the magnetic pole gap position, and the cooling gas and the opening can be effectively prevented from affecting the magnetic furnace structure, thereby avoiding insufficient axial supporting force of the magnetic suspension, achieving improved heat dissipation cooling of the magnetic suspension bearing while avoiding affecting the magnetic suspension magnetic circuit, ensuring sufficient magnetic suspension supporting force, and effectively reducing the influence of the gas force on the axial force.

[0061] In some embodiments,

[0062] It also includes a pressure plate 4, the pressure plate 4 is located between the axial stator 1 and the thrust plate 3, and an axial end surface of the pressure plate 4 is connected to the radial outer side 11 of the axial stator 1, and the other axial end surface of the pressure plate 4 is opposite to the thrust plate 3;

[0063] The magnetic pole position of the axial stator 1 includes the portion of the pressure plate 4 opposite to the thrust disk 3, and the portion of the radial inner portion 12 opposite to the thrust disk 3, a first gap 05 is provided between the pressure plate 4 and the radial inner portion 12, the first thrust disk ventilation hole 01 is opposite to the first gap 05 in the axial direction, and a radial dimension of the first gap 05 is greater than or equal to a radial dimension of an end of the first thrust disk ventilation hole 01 opposite to the coil slot 13.

[0064] The first thrust plate ventilation hole of the present invention extends from one end of the thrust plate located between the axial stator and the rotor to the other end of the thrust plate opposite to the coil slot one, which can cool and dissipate heat of the coil inside the stator, and the end of the first thrust plate ventilation hole opposite to the coil slot one is preferably arranged between the axial upper and lower magnetic poles directly opposite to the coil, and the aperture size is ≤ the radial spacing between the axial upper and lower magnetic poles of the stator, which can enable the first thrust plate ventilation hole to further effectively avoid the magnetic pole position and further avoid affecting the magnetic circuit, and the first thrust plate ventilation hole is connected to the ventilation paths at both ends without obstruction, and can also make the airflow resistance at both ends of the thrust plate small and the fluidity good.

[0065] In some embodiments,

[0066] In any radial cross section of the thrust plate 3, the cross-sectional area of ​​the magnetic path flow position of the axial stator 1 = the radial cross-sectional area of ​​the thrust plate and the corresponding part of the axial stator 1 - the cross-sectional area of ​​the first thrust plate ventilation hole 01 ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 1.

[0067] The present invention further sets the relationship in any radial cross-section of the thrust plate: the cross-sectional area of ​​the magnetic circuit flow position of the axial stator 1 = the radial cross-sectional area of ​​the thrust plate and the relative parts of the axial stator 1 - the cross-sectional area of ​​the ventilation hole of the first thrust plate ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 1, so that other magnetic circuit parts on the thrust plate that are different from the magnetic pole position will not experience magnetic field saturation before the magnetic pole position, thereby ensuring the formation of a normal magnetic flux circuit and ensuring the continuous and effective provision of magnetic suspension supporting force.

[0068] In some embodiments,

[0069] Inside the coil slot 13, there is a second gap between the radial inner side of the coil 5 and the radial inner portion 12, forming a first gas flow path 06.

[0070] The axial stator 1 also includes an axial outer portion 14, which is arranged in the axial direction of the magnetic bearing relative to the coil 5 and away from the thrust plate 3. Inside the coil slot 13, there is also a third gap between the axial outer portion 14 and the coil 5, forming a bearing stator ventilation slot 04;

[0071] A bearing stator ventilation hole 03 is provided on the axial outer portion 14 of the axial stator 1. The bearing stator ventilation hole 03 penetrates from one axial end surface of the axial outer portion 14 to the other axial end surface to be connected with the bearing stator ventilation groove 04, and further connected to the first thrust plate ventilation hole 01 through the first gas flow path 06.

[0072] The present invention can further accelerate the gas flow in the axial stator coil slot cavity by setting bearing stator ventilation holes and ventilation slots (multiple gas flow paths) in the axial stator coil slot, thereby achieving effective autonomous heat dissipation of the axial coil and the thrust plate.

[0073] In some embodiments,

[0074] Along the axial direction of the thrust plate 3, the first thrust plate ventilation hole 01 is an inclined hole structure whose extension direction is not parallel to the axis of the thrust plate 3, and when observing from the axial end face of the air inlet side of the thrust plate 3 toward the axial end face of the air outlet side, the rotation direction of the thrust plate 3 is toward the first rotation direction, and the extension direction of the first thrust plate ventilation hole 01 from the axial end face of the air inlet side of the thrust plate toward the axial end face of the air outlet side is toward the second rotation direction, and the second rotation direction is opposite to the first rotation direction.

[0075] The present invention also arranges the ventilation hole of the first thrust plate to extend from the axial end face on the air inlet side toward the axial end face on the air outlet side in a second rotation direction, and the second rotation direction is opposite to the first rotation direction (the rotation direction of the thrust plate). When the rotor drives the thrust plate to rotate at a high speed, negative pressure is generated to suck out hot air at one end and discharge it to the outside, thereby increasing the gas flow rate, realizing active ventilation and heat exchange of the thrust plate itself, accelerating gas flow, saving energy consumption, improving heat dissipation performance and improving energy efficiency.

[0076] In some embodiments,

[0077] There are multiple first thrust plate ventilation holes 01, and the multiple first thrust plate ventilation holes 01 are arranged at intervals along the circumferential direction of the thrust plate 3, and the extension direction of each first thrust plate ventilation hole 01 from the axial end face on the air intake side to the axial end face on the air outlet side is toward the second rotation direction, which is opposite to the first rotation direction of the thrust plate 3.

[0078] The present invention proposes a magnetic levitation rotating machine (preferably a blower) with active and efficient heat dissipation. The first thrust plate ventilation hole adopts an inclined hole scheme to realize its own active air suction heat exchange through high speed, increase the gas flow rate introduced, accelerate the cooling of the axial magnetic bearing, and cooperate with the overall active pure air cooling of the blower to dissipate heat. The coaxial impeller cooling at the other end of the main impeller or the rotor rotation negative pressure cooling or the main impeller leakage cooling is used to change the previous external passive heat dissipation into internal active heat dissipation, improve the heat dissipation efficiency and reduce the heat dissipation cost. This blower cooling scheme can effectively ventilate and dissipate heat for motor stators, motor rotors, magnetic bearings, etc., and can also better dissipate heat for axial magnetic bearings, thereby improving the stability of the magnetic levitation system.

[0079] In some embodiments,

[0080] The thrust plate 3 is provided with a second thrust plate ventilation hole 02 extending from the other axial end surface to the one axial end surface thereof, and the second thrust plate ventilation hole 02 is misaligned with the first thrust plate ventilation hole 01 and is not connected;

[0081] The radial outer portion 21 and the radial inner portion 22 are spaced apart in the radial direction of the axial stator 2, and a coil slot 23 is formed therebetween, a coil 5' is arranged in the coil slot 23, one end of the second thrust plate ventilation hole 02 located on the one axial end face of the thrust plate 3 is located between the radial inner portion 12 of the axial stator 1 and the rotor 6, one end of the second thrust plate ventilation hole 02 located on the other axial end face of the thrust plate 3 is opposite to the position of the coil slot 23 in the axial direction, and the second thrust plate ventilation hole 02 is not opposite to the magnetic pole position of the axial stator 2.

[0082] The present invention further ensures that the end of the second thrust plate ventilation hole opposite to the coil slot 2 is not opposite to the magnetic pole position of the axial stator 2, so that the thrust plate end face is not punched at the magnetic pole position opposite to the axial stator 2, so that cooling air cannot directly reach the magnetic pole gap position of the axial stator 2, which can further effectively avoid the cooling gas and the opening from affecting the magnetic furnace structure, further avoid insufficient axial supporting force of the magnetic suspension, further achieve improved heat dissipation cooling of the magnetic suspension bearing, avoid affecting the magnetic suspension magnetic circuit, further improve the magnetic suspension supporting force, and effectively reduce the influence of the gas force on the axial force.

[0083] In some embodiments,

[0084] It also includes a second pressure plate 4', the second pressure plate 4' is located between the second axial stator 2 and the thrust plate 3, and one axial end surface of the second pressure plate 4' is connected to the second radial outer portion 21 of the second axial stator 2, and the other axial end surface of the second pressure plate 4' is opposite to the thrust plate 3;

[0085] The magnetic pole position of the axial stator 2 includes the portion of the pressure plate 2 4' opposite to the thrust plate 3, and the portion of the radial inner portion 22 opposite to the thrust plate 3, a fourth gap 07 is provided between the pressure plate 2 4' and the radial inner portion 22, the second thrust plate ventilation hole 02 is opposite to the fourth gap 07 in the axial direction, and a radial dimension of the fourth gap 07 is greater than or equal to a radial dimension of the second thrust plate ventilation hole 02 and one end of the coil slot 23.

[0086] The second thrust plate ventilation hole of the present invention extends from one end of the thrust plate located between the axial stator and the rotor to the other end of the thrust plate opposite to the coil slot one, which can cool and dissipate heat of the coil inside the stator, and the end of the second thrust plate ventilation hole opposite to the coil slot two is preferably arranged between the axial upper and lower magnetic poles directly opposite to the coil, and the aperture size is ≤ the radial spacing between the axial upper and lower magnetic poles of the stator, which can enable the second thrust plate ventilation hole to further effectively avoid the magnetic pole position and further avoid affecting the magnetic circuit, and the second thrust plate ventilation hole is connected to the ventilation paths at both ends without obstruction, and can also make the airflow resistance at both ends of the thrust plate small and the fluidity good.

[0087] In some embodiments,

[0088] In each radial cross section of the thrust plate 3, the cross-sectional area of ​​the magnetic path flow position of the axial stator 2 2 = the radial cross-sectional area of ​​the thrust plate and the corresponding part of the axial stator 2 2 - the cross-sectional area of ​​the second thrust plate ventilation hole 02 ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 2 2.

[0089] The present invention further provides that the end of the second thrust plate ventilation hole opposite to the coil slot 2 is arranged between the upper and lower magnetic poles of the axial stator 2 and directly opposite to the coil, and further makes the aperture size of this end of the second thrust plate ventilation hole ≤ the radial spacing between the upper and lower magnetic poles of the axial stator 2, so that the second thrust plate ventilation hole can further effectively avoid the magnetic pole position of the axial stator 2, further avoid affecting the magnetic circuit, and the second thrust plate ventilation hole is connected with the ventilation paths at both ends without obstruction, and can also make the airflow resistance at both ends of the thrust plate small and the fluidity good.

[0090] In some embodiments,

[0091] Inside the coil slot 23, there is a fifth gap between the radial inner side of the coil 2 5' and the radial inner portion 22, forming a second gas flow path 08.

[0092] The second axial stator 2 further includes a second axial outer portion 24, which is arranged in the axial direction of the magnetic bearing relative to the second coil 5' and away from the thrust plate 3. Inside the second coil slot 23, there is also a sixth gap between the second axial outer portion 24 and the second coil 5', forming a bearing stator ventilation slot 204';

[0093] A bearing stator ventilation hole 203' is provided on the axial outer portion 24 of the axial stator 2. The bearing stator ventilation hole 203' passes through one axial end surface of the axial outer portion 24 to the other axial end surface to be connected with the bearing stator ventilation groove 204', and further connected to the second thrust plate ventilation hole 02 through the second gas flow path 08.

[0094] The present invention can further accelerate the gas flow in the coil slot cavity of the axial stator 2 by setting bearing stator ventilation holes and ventilation slots (multiple gas flow paths) in the coil slot of the axial stator 2, thereby achieving effective autonomous heat dissipation of the axial coil and the thrust plate.

[0095] In some embodiments,

[0096] Along the axial direction of the thrust plate 3, the second thrust plate ventilation hole 02 is an inclined hole structure whose extension direction is not parallel to the axis of the thrust plate 3, and when observing from the axial end face of the air inlet side of the thrust plate 3 toward the axial end face of the air outlet side, the rotation direction of the thrust plate 3 is toward the third rotation direction, and the extension direction of the second thrust plate ventilation hole 02 from the axial end face of the air inlet side of the thrust plate 3 toward the axial end face of the air outlet side is toward the fourth rotation direction, and the fourth rotation direction is opposite to the third rotation direction.

[0097] The present invention also arranges the ventilation hole of the first thrust plate to extend from the axial end face on the air inlet side toward the axial end face on the air outlet side in a third rotation direction (which may be the same as or opposite to the first rotation direction), and the fourth rotation direction is opposite to the third rotation direction (the rotation direction of the thrust plate). When the rotor drives the thrust plate to rotate at a high speed, negative pressure is generated to suck out hot air at one end and discharge it to the outside, thereby increasing the gas flow rate, realizing active ventilation and heat exchange of the thrust plate itself, accelerating gas flow, saving energy consumption, improving heat dissipation performance and improving energy efficiency.

[0098] In some embodiments,

[0099] There are multiple second thrust plate ventilation holes 02, and the multiple second thrust plate ventilation holes 02 are arranged at intervals along the circumferential direction of the thrust plate 3, and the extension direction of each second thrust plate ventilation hole 02 from the axial end face on the air inlet side of the thrust plate to the axial end face on the air outlet side is toward the fourth rotation direction, which is opposite to the third rotation direction of the thrust plate 3.

[0100] The present invention proposes a magnetic levitation rotating machine (preferably a blower) with active and efficient heat dissipation. The second thrust plate ventilation hole adopts an inclined hole scheme to realize its own active air suction heat exchange through high speed, increase the gas flow rate introduced, accelerate the cooling of the axial magnetic bearing, and cooperate with the overall active pure air cooling of the blower. The coaxial impeller cooling at the other end of the main impeller or the rotor rotation negative pressure cooling or the main impeller leakage cooling is used to change the previous external passive heat dissipation into internal active heat dissipation, improve the heat dissipation efficiency and reduce the heat dissipation cost. This blower cooling scheme can effectively ventilate and dissipate heat for motor stators, motor rotors, magnetic bearings, etc., and can also better dissipate heat for axial magnetic bearings, thereby improving the stability of the magnetic levitation system.

[0101] The axial magnetic bearing of the present invention adopts active ventilation cooling. The thrust plate is installed on the rotor and has an inclined hole between the two magnetic poles of the thrust plate. The thrust plate is provided with several staggered X-shaped inclined holes from the inside to the outside and from the outside to the inside in the axial and radial spaces (in order to cooperate with the whole machine solution to cool the thrust plate, only one air intake inclined hole can be provided for axial cooling). The air intake direction is opposite to the rotation direction of the rotor. When the thrust plate is driven by the rotor to rotate at a high speed, negative pressure is generated to suck out the hot air at one end and discharge it to the outside, thereby increasing the gas flow rate introduced, realizing active ventilation and heat exchange of the thrust plate itself, accelerating the gas flow, and at the same time cooperating with the ventilation holes and ventilation grooves in the axial stator coil slots to accelerate the gas flow in the axial stator coil slot cavity, thereby realizing effective autonomous heat dissipation of the axial coil and the thrust plate.

[0102] According to the principle of axial magnetic bearing, the relative position of the thrust plate and the axial magnetic pole is the output position, that is, the thrust plate end face facing the magnetic pole position cannot be punched to avoid insufficient axial force. At the same time, the cooling air cannot directly reach the magnetic pole gap position, which can reduce the effect of gas force on the axial force. According to the requirements of axial magnetic circuit flow, in order to ensure that the magnetic field saturation does not occur at other positions before the magnetic pole position, in the radial circumferential direction, the cross-sectional area of ​​the magnetic circuit flow position ≥ the cross-sectional area of ​​the magnetic pole position. The opening position of the thrust plate with inclined hole is opened within the magnetic circuit. In each radial circumferential direction, the cross-sectional area of ​​the magnetic circuit flow position = the radial circumferential cross-sectional area of ​​the thrust plate - the cross-sectional area in the same direction of the hole position ≥ the cross-sectional area of ​​the magnetic pole position. The air inlet at the upper end of the inclined hole is located between the axial upper and lower magnetic poles and directly opposite to the coil, and the aperture size is ≤ the radial spacing between the upper and lower magnetic poles of the axial stator; the air inlet at the lower end of the inclined hole is located at the aperture of the non-magnetic conductive part of the inner ring of the axial lower magnetic pole, and the aperture size is < the radial spacing between the lower magnetic pole of the axial stator and the rotor. Both ends of the aperture are connected with the axial stator ventilation path. The airflow resistance at both ends of the thrust plate is small, the fluidity is good, and the axial output is not affected.

[0103] The entire system uses an active pure air-cooled cooling system. The cold air is driven by the coaxial impeller at the other end of the main impeller or the rotor rotates to centrifugally inlet or the main impeller leaks inlet. No additional cooling drive motor is required. The cooling cold air flow is adjusted by the motor speed and no additional controller is required. The overall internal flow channel layout guides the cold air to each component for targeted heat dissipation. The entire cooling system has a simple structure and the heat dissipation process is efficient and reliable.

[0104] The beneficial effects of the present invention are as follows:

[0105] 1. The present invention sets an oblique hole on the thrust plate for high-heat generating components and cooperates with the axial coil ventilation groove, and uses negative pressure to absorb heat through the oblique hole flow channel, which can actively cool the thrust plate itself and increase the cooling flow to accelerate the heat dissipation of the axial coil. The active pure air cooling heat dissipation system reduces the heat dissipation cost, and targeted ventilation of heat generating components can effectively accelerate cooling and improve reliability;

[0106] 2. The present invention also cooperates with the flow channel structure layout of the whole machine, and carries out targeted ventilation and heat dissipation on the heat-generating components, so as to realize effective ventilation and cooling of the overall heat-generating components of the blower and improve the stability of the magnetic levitation system; it realizes an integrated high-efficiency pure air-cooled heat dissipation system, which can ensure that the blower has sufficient heat dissipation air volume under various working conditions. The cold air is directly driven by the motor rotor, the control logic is simple, and the heat dissipation system has high reliability.

[0107] The present invention also provides a magnetic suspension rotating machine (preferably a rotating machine such as a motor, a blower, a ventilator or a compressor), which includes the aforementioned magnetic suspension bearing.

[0108] Figure 1 , Figure 3 The figure shows the internal axial bearing cooling path of the magnetic levitation machinery (preferably a blower) of the present invention. The axial stator one / two is provided with bearing stator ventilation holes, and the coil slot is provided with a bearing stator ventilation slot, which is preferably radial, annular or spiral. The thrust plate 3 is provided with several staggered X-shaped inclined holes from the inside to the outside and from the outside to the inside in the axial and radial space (the holes from the inside to the outside or the holes from the outside to the inside can exist alone, or they can exist at the same time). One of the openings of the inclined hole is directly opposite to the coil between the axial inner and outer magnetic poles, corresponding to the wire slot ventilation. There is no requirement for the hole type. For the convenience of machining and process, circular holes, rectangular circular holes or elliptical holes are preferred. There are two cooling paths. The first cooling path is from the ventilation holes on the axial stator, through the ventilation slots, the inner ring of the axial coil, and between the axial inner and outer magnetic poles, and then discharged through the oblique holes of the thrust plate; the second cooling path is from the oblique holes of the thrust plate, through the axial inner and outer magnetic poles of the axial stator, the inner ring of the axial coil, the ventilation slots of the axial stator, and then discharged through the ventilation holes of the axial stator (if there is only one hole from the inside to the outside or from the outside to the inside, there is only one path). During operation, the air intake direction of the oblique holes of the thrust plate is opposite to the rotation direction of the rotor. The thrust plate uses negative pressure to suck out the heat dissipation gas, increase the gas flow, accelerate the heat exchange between the thrust plate and the axial coil, and cooperate with the cooling path of the overall solution to achieve effective heat dissipation. In order to make the thrust plate intake negative pressure air, the intake direction must always be opposite to the rotor rotation direction. Therefore, the rotation direction of the thrust plate oblique hole is related to the thrust plate intake direction and the rotor rotation direction. If the rotation direction of the intake rotor at the left end of the thrust plate is clockwise when viewed from the right end, the thrust plate is a right-handed oblique hole. If the rotation direction of the intake rotor at the left end of the thrust plate is counterclockwise when viewed from the right end, the thrust plate is a left-handed oblique hole. Similarly, if the directions do not match, the heat dissipation effect will be weakened and the heat dissipation efficiency will be reduced.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A magnetic bearing, characterized in that: include: An axial stator (1), an axial stator (2) and a thrust plate (3), wherein the thrust plate (3) is arranged between the axial stator (1) and the axial stator (2) in the axial direction of the magnetic bearing, and a first thrust plate ventilation hole (01) is provided on the thrust plate (3) from one axial end face to the other axial end face thereof, the axial stator (1) comprises a radial outer portion (11) and a radial inner portion (12), the radial outer portion (11) and the radial inner portion (12) are arranged at intervals in the radial direction of the axial stator (1), and a coil slot (13) is formed between the two, and a coil (5) is provided in the coil slot (13), The axial stator 2 (2) comprises a radial outer portion 2 (21) and a radial inner portion 2 (22), One end of the first thrust plate ventilation hole (01) located on the other axial end face of the thrust plate (3) is located between the radial inner side 2 (22) of the axial stator 2 (2) and the rotor (6), and one end of the first thrust plate ventilation hole (01) located on the one axial end face of the thrust plate (3) is opposite to the position of the coil slot 1 (13) in the axial direction, and the first thrust plate ventilation hole (01) is not opposite to the magnetic pole position of the axial stator 1 (1).

2. The magnetic bearing according to claim 1, characterized in that: It also includes a pressure plate (4), the pressure plate (4) being located between the axial stator (1) and the thrust plate (3), and an axial end surface of the pressure plate (4) being connected to the radial outer side portion (11) of the axial stator (1), and the other axial end surface of the pressure plate (4) being opposite to the thrust plate (3); The magnetic pole position of the axial stator (1) includes a portion of the pressure plate (4) opposite to the thrust disk (3) and a portion of the radial inner portion (12) opposite to the thrust disk (3); a first gap (05) is provided between the pressure plate (4) and the radial inner portion (12); the first thrust disk ventilation hole (01) and the first gap (05) are opposite to each other in the axial direction, and a radial dimension of the first gap (05) is greater than or equal to a radial dimension of an end of the first thrust disk ventilation hole (01) opposite to the coil slot (13).

3. The magnetic bearing according to claim 2, characterized in that: In any radial cross section of the thrust disk (3), the cross-sectional area of ​​the magnetic path flow position of the axial stator one (1) = the radial cross-sectional area of ​​the thrust disk and the corresponding part of the axial stator one (1) - the cross-sectional area of ​​the first thrust disk ventilation hole (01) ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator one (1).

4. The magnetic bearing according to any one of claims 1 to 3, characterized in that: Inside the coil slot 1 (13), a second gap is provided between the radial inner side of the coil 1 (5) and the radial inner side portion 1 (12), forming a first gas flow path (06). The axial stator (1) further comprises an axial outer portion (14), which is arranged in the axial direction of the magnetic bearing relative to the coil (5) and away from the thrust plate (3), and inside the coil slot (13), there is also a third gap between the axial outer portion (14) and the coil (5), forming a bearing stator ventilation slot (04); A bearing stator ventilation hole (03) is provided on the axial outer side portion (14) of the axial stator (1). The bearing stator ventilation hole (03) extends from one axial end surface of the axial outer side portion (14) to the other axial end surface to communicate with the bearing stator ventilation groove (04), and further communicates with the first thrust plate ventilation hole (01) through the first gas flow path (06).

5. The magnetic bearing according to any one of claims 1 to 4, characterized in that: Along the axial direction of the thrust plate (3), the first thrust plate ventilation hole (01) is an inclined hole structure whose extension direction is not parallel to the axis of the thrust plate (3); when observing from the axial end face of the air inlet side of the thrust plate (3) toward the axial end face of the air outlet side, the rotation direction of the thrust plate (3) is toward a first rotation direction; the extension direction of the first thrust plate ventilation hole (01) from the axial end face of the air inlet side of the thrust plate (3) toward the axial end face of the air outlet side is toward a second rotation direction, and the second rotation direction is opposite to the first rotation direction.

6. The magnetic bearing according to claim 5, characterized in that: There are a plurality of first thrust plate ventilation holes (01), which are arranged at intervals along the circumferential direction of the thrust plate (3), and each of the first thrust plate ventilation holes (01) extends from the axial end face on the air inlet side of the thrust plate toward the axial end face on the air outlet side toward a second rotation direction, which is opposite to the first rotation direction of the thrust plate (3).

7. The magnetic bearing according to claim 1, characterized in that: The thrust disc (3) is provided with a second thrust disc ventilation hole (02) extending from the other axial end surface to the one axial end surface thereof, and the second thrust disc ventilation hole (02) is offset from the first thrust disc ventilation hole (01) and is not connected; The radial outer portion 2 (21) and the radial inner portion 2 (22) are spaced apart in the radial direction of the axial stator 2 (2), and a coil slot 2 (23) is formed therebetween. A coil 2 (5') is arranged in the coil slot 2 (23). One end of the second thrust plate ventilation hole (02) located on the axial one end face of the thrust plate (3) is located between the radial inner portion 1 (12) of the axial stator 1 (1) and the rotor (6). One end of the second thrust plate ventilation hole (02) located on the other axial end face of the thrust plate (3) is opposite to the position of the coil slot 2 (23) in the axial direction, and the second thrust plate ventilation hole (02) is not opposite to the magnetic pole position of the axial stator 2 (2).

8. The magnetic bearing according to claim 7, characterized in that: It also includes a second pressure plate (4'), the second pressure plate (4') is located between the second axial stator (2) and the thrust plate (3), and one axial end surface of the second pressure plate (4') is connected to the second radial outer portion (21) of the second axial stator (2), and the other axial end surface of the second pressure plate (4') is opposite to the thrust plate (3); The magnetic pole position of the axial stator 2 (2) includes a portion of the pressure plate 2 (4') opposite to the thrust plate (3), and a portion of the radial inner portion 2 (22) opposite to the thrust plate (3); a fourth gap (07) is provided between the pressure plate 2 (4') and the radial inner portion 2 (22); the second thrust plate ventilation hole (02) and the fourth gap (07) are opposite to each other in the axial direction, and a radial dimension of the fourth gap (07) is greater than or equal to a radial dimension of an end of the second thrust plate ventilation hole (02) opposite to the coil slot 2 (23).

9. The magnetic bearing according to claim 8, characterized in that: In each radial cross section of the thrust disk (3), the cross-sectional area of ​​the magnetic path flow position of the axial stator 2 (2) = the radial cross-sectional area of ​​the thrust disk and the corresponding part of the axial stator 2 (2) - the cross-sectional area of ​​the second thrust disk ventilation hole (02) ≥ the cross-sectional area of ​​the magnetic pole position of the axial stator 2 (2).

10. The magnetic bearing according to claim 7, characterized in that: Inside the coil slot 2 (23), a fifth gap is provided between the radial inner side of the coil 2 (5') and the radial inner portion 2 (22), forming a second gas flow path (08). The axial stator 2 (2) further comprises an axial outer portion 2 (24), the axial outer portion 2 (24) being arranged in the axial direction of the magnetic bearing relative to the coil 2 (5') and away from the thrust plate (3), and inside the coil slot 2 (23), there is also a sixth gap between the axial outer portion 2 (24) and the coil 2 (5'), forming a bearing stator ventilation slot 2 (04'); A bearing stator ventilation hole 2 (03') is provided on the axial outer side 2 (24) of the axial stator 2 (2). The bearing stator ventilation hole 2 (03') extends from one axial end surface of the axial outer side 2 (24) to the other axial end surface to communicate with the bearing stator ventilation groove 2 (04'), and is further connected to the second thrust plate ventilation hole (02) through the second gas flow path (08).

11. The magnetic bearing according to claim 7, characterized in that: Along the axial direction of the thrust plate (3), the second thrust plate ventilation hole (02) is an inclined hole structure whose extension direction is not parallel to the axis of the thrust plate (3); when observing from the axial end face of the air inlet side of the thrust plate (3) toward the axial end face of the air outlet side, the rotation direction of the thrust plate (3) is toward a third rotation direction; the extension direction of the second thrust plate ventilation hole (02) from the axial end face of the air inlet side of the thrust plate (3) toward the axial end face of the air outlet side is toward a fourth rotation direction, and the fourth rotation direction is opposite to the third rotation direction.

12. The magnetic bearing according to claim 11, characterized in that: There are a plurality of second thrust plate ventilation holes (02), which are arranged at intervals along the circumferential direction of the thrust plate (3), and each of the second thrust plate ventilation holes (02) extends from the axial end face on the air inlet side of the thrust plate toward the axial end face on the air outlet side toward a fourth rotation direction, which is opposite to the third rotation direction of the thrust plate (3).

13. A magnetically suspended rotating machine, characterized in that: The invention comprises the magnetic bearing according to any one of claims 1 to 12.

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