A magnetic bearing and pump arrangement

Abstract

The application provides a magnetic bearing and a pump device, the magnetic bearing comprising: a rotor and a stator, the stator being arranged circumferentially around the rotor; the rotor having a central axis and being a rotor permanent magnet; the stator comprising: at least two pairs of radial stator poles, the radial stator poles being uniformly distributed along the circumference of the rotor; and a stator coil corresponding to each of the at least two pairs of radial stator poles. The application provides a magnetic bearing and a pump device, so that the magnetic bearing structure is more compact and simple, the magnetic bearing can be miniaturized without reducing the performance of the magnetic bearing, and the application prospect of the magnetic bearing is increased.

Description

Technical Field

[0001] This application relates to the field of bearing technology, and in particular to a magnetic bearing and pump device. Background Technology

[0002] Magnetic bearings, also known as magnetic levitation bearings, are a new type of high-performance bearing. They utilize magnetic force to levitate the rotor in the air, eliminating any mechanical contact between the rotor and stator. Compared to traditional rolling bearings, sliding bearings, and oil film bearings, magnetic bearings offer advantages such as low noise, long lifespan, no lubrication required, and no oil contamination, making them particularly suitable for high-speed, vacuum, and ultra-clean environments.

[0003] Currently, magnetic bearings can be divided into two categories based on the source of their bias magnetic field: The first category is active magnetic bearings. These bearings require a bias current to be applied to the coil to provide the bias magnetic field. An additional control current provides controllable magnetic levitation. This type of bearing is relatively large in size, weight, and power consumption, making it unsuitable for miniaturization. The second category is permanent magnet biased magnetic bearings. In these bearings, the bias magnetic field is generated by a permanent magnet, and the electromagnet only provides a control magnetic field to balance the load or interference. This results in a significantly smaller size. Compared to active magnetic bearings, it reduces the additional power consumption caused by the bias current, and the overall size of the bearing is also reduced due to the smaller size of the electromagnet coil, making miniaturized product applications possible.

[0004] Currently, permanent magnet bias magnetic levitation bearings can be roughly divided into two types according to the integration degree of the control module: one type uses independent magnetic bearing modules in the axial and radial directions to achieve five degrees of freedom support. This design makes the overall axial dimension longer and the system more complex; the other type integrates the radial and axial magnetic bearing modules together. However, this design generally leads to a complex rotor structure design, a large stator radial dimension, low or almost no passive control stiffness in the axial and tilt directions, and high power consumption of the magnetic bearing, making it unsuitable for miniaturization.

[0005] Therefore, it is necessary to provide a new magnetic bearing structure that can miniaturize the magnetic bearing without reducing its performance, thereby increasing the application prospects of the magnetic bearing. Summary of the Invention

[0006] This application provides a magnetic bearing and pump device that can miniaturize the magnetic bearing without reducing its performance, thereby increasing the application prospects of the magnetic bearing.

[0007] One aspect of this application provides a magnetic bearing comprising: a rotor and a stator, the stator being circumferentially disposed around the rotor; the rotor having a central axis and being a rotor permanent magnet; the stator comprising: at least two pairs of radial stator poles uniformly distributed along the circumference of the rotor; and stator coils correspondingly wound around each of the at least two pairs of radial stator poles.

[0008] In some embodiments of this application, the magnetic bearing further includes: an active control system configured to provide active stability control of the radial displacement of the rotor, the active control system including: a displacement sensor for detecting the radial offset of the rotor; and a controller for receiving the detection result of the displacement sensor and configured to output a control current to the stator coil to bring the radial offset of the rotor back within the offset threshold when the radial offset detected by the displacement sensor is greater than the offset threshold.

[0009] In some embodiments of this application, the radial stator poles are not magnetically connected to each other.

[0010] In some embodiments of this application, the rotor permanent magnet is magnetized along the direction of the central axis.

[0011] In some embodiments of this application, the ratio of the outer diameter of the rotor to the axial height of the rotor is greater than or equal to 1.5.

[0012] In some embodiments of this application, the ratio of the outer diameter to the inner diameter of the rotor is greater than or equal to 1.1.

[0013] In some embodiments of this application, the absolute value of the difference between the height of the rotor permanent magnet and the height of the radial stator pole is less than or equal to 70% of the height of the radial stator pole.

[0014] In some embodiments of this application, the distance between the rotor and the stator is less than or equal to 10% of the rotor's outer diameter.

[0015] In some embodiments of this application, the radial stator poles are in the shape of a concave "U", with the concave portion of the "U" facing the rotor and forming a mounting groove. The stator coils are wound in the mounting groove, and the upper and lower axial sides of the mounting groove are defined as upper teeth and lower teeth, respectively.

[0016] In some embodiments of this application, the ratio of the absolute value of the difference between the upper and lower tooth heights of the radial stator poles to the lower tooth height is less than or equal to 80%.

[0017] In some embodiments of this application, the ratio of the diameter of the circle formed by the upper teeth of the at least two pairs of radial stators to the diameter of the circle formed by the lower teeth of the at least two pairs of radial stators is less than or equal to 20%.

[0018] In some embodiments of this application, the rotor is an integral ring and is made of only one type of permanent magnet material.

[0019] In some embodiments of this application, the material of the rotor permanent magnet is neodymium iron boron, and / or the material of the radial stator poles is a magnetically conductive ferromagnetic material.

[0020] Another aspect of this application provides a pump device, comprising: a pump head housing; an impeller disposed inside the pump head housing; and a rotor of a magnetic bearing as described above, the rotor disposed inside the pump head housing, the magnetic bearing being configured to drive the impeller to rotate about the central axis.

[0021] In some embodiments of this application, the pump device includes: a stator of a magnetic bearing as described above; a pump housing; a drive device disposed within the pump housing for providing rotational force to the magnetic bearing; the stator of the magnetic bearing is disposed within the pump housing, and the pump head housing is detachably connected to the pump housing.

[0022] In some embodiments of this application, the rotor of the magnetic bearing is disposed within an annular groove defined by the pump head housing, and the drive device is close to one end of the rotor, extends into the space defined by the annular groove of the pump head housing for accommodating the rotor, and is surrounded by the rotor.

[0023] In some embodiments of this application, the stator is arranged around an annular groove of the pump head housing for receiving the rotor, and a pump head seat is provided inside the pump housing for receiving at least a portion of the pump head housing, wherein at least a portion of the pump head seat has a shape complementary to at least a portion of the pump head housing.

[0024] This application provides a magnetic bearing and pump device, which makes the magnetic bearing structure more compact and simple, and can miniaturize the magnetic bearing without reducing its performance, thereby increasing the application prospects of the magnetic bearing. Attached Figure Description

[0025] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are for illustrative purposes and should not be construed as necessarily drawn to scale. Wherein:

[0026] Figure 1 This is a top view of the magnetic bearing described in an embodiment of this application;

[0027] Figure 2 The magnetic bearing described in the embodiments of this application is along Figure 1 Schematic diagram of the longitudinal cross-sectional structure of line AA;

[0028] Figure 3 This is a schematic diagram of the bias magnetic field principle based on the longitudinal section of the magnetic bearing in an embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the axial passive control magnetic circuit based on the longitudinal section of the magnetic bearing in an embodiment of this application.

[0030] Figure 5 This is a schematic diagram of the passive tilt control magnetic circuit based on the longitudinal section of the magnetic bearing in this embodiment of the application.

[0031] Figure 6 This is a schematic diagram of the radial active control magnetic circuit based on the longitudinal section of the magnetic bearing, according to an embodiment of this application.

[0032] Figure 7 This is a schematic diagram of the pump device according to an embodiment of this application. Detailed Implementation

[0033] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to create and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the illustrated embodiments, but rather to the widest scope of the technical solutions protected by the claims.

[0034] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0035] Figure 1 This is a top view of the magnetic bearing described in an embodiment of this application. Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of the magnetic bearing described in an embodiment of this application. Specifically, Figure 2 For along Figure 1 The longitudinal cross-sectional view at the dashed line AA. The magnetic bearing described in the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0036] Embodiments of this application provide a magnetic bearing 100, see reference. Figure 1 and Figure 2 As shown, it includes a rotor 10 and a stator 20, the stator 20 being arranged circumferentially around the rotor 10, the stator 20 being configured to provide passive stability control of axial and tilt displacements of the rotor 10 and active stability control of radial displacement.

[0037] In some embodiments of this application, the distance between the rotor 10 and the stator 20 is less than or equal to 10% of the rotor's outer diameter. Typically, those skilled in the art, in order to achieve miniaturized magnetic bearings, modify the material or composition of the rotor or stator, without studying the dimensional relationships between the various components of the magnetic bearing to achieve miniaturization while maintaining its performance. The inventors of this application creatively adopted a completely different research path, and surprisingly discovered during the research and development process that the relationship between the distance between the rotor and stator and the rotor diameter directly affects the performance of the magnetic bearing. In particular, by setting the distance between the rotor 10 and the stator 20 to be less than or equal to 10% of the rotor's outer diameter, a miniaturized magnetic bearing can be achieved without reducing or improving its performance, and the overall design of the magnetic bearing is made more compact.

[0038] Continue to refer to Figure 1 and Figure 2 As shown, the rotor 10 is generally annular, for example, circular, and has a central axis Z. The rotor 10 is configured to rotate about the central axis Z. In specific applications, a rotation actuation device (not shown in the figure) can be set in the annular area of ​​the rotor 10, such as various types of motors that can be used by those skilled in the art based on the general principles disclosed in this application.

[0039] Continue to refer to Figure 2 As shown, the rotor 10 is a rotor permanent magnet 12. In this embodiment, the rotor permanent magnet 12 is annular.

[0040] In some embodiments of this application, the rotor permanent magnet 12 is magnetized along the direction of the central axis.

[0041] In some embodiments of this application, the rotor 10 (rotor permanent magnet 12) is an integral ring and made of only one type of permanent magnet material. Using a rotor 10 with this structure can significantly simplify the overall structure of the magnetic bearing, facilitating further miniaturization of the magnetic bearing.

[0042] In some embodiments of this application, the material of the rotor permanent magnet 12 includes rubidium iron boron.

[0043] In some embodiments of this application, the ratio of the outer diameter of the rotor 10 (i.e., the outer diameter of the rotor permanent magnet 12) to the axial height H1 of the rotor 10 (i.e., the height of the rotor permanent magnet 12) is greater than or equal to 1.5.

[0044] In some embodiments of this application, the ratio of the outer diameter to the inner diameter of the rotor 10 (i.e., the outer diameter to the inner diameter of the rotor permanent magnet 12) is greater than or equal to 1.1.

[0045] Continue to refer to Figure 1 and Figure 2 As shown, the stator 20 includes: at least two pairs of radial stator poles 21, which are uniformly distributed along the circumference of the rotor 10; and stator coils 22, which are wound around each of the at least two pairs of radial stator poles 21.

[0046] In some embodiments of this application, the radial stator poles 21 are not magnetically connected to each other. That is, each radial stator pole 21 is independent in the magnetic circuit. In other words, there are no magnetically conductive parts connecting the at least two pairs of radial stator poles 21, which is beneficial for creating a magnetic levitation bearing with a simple structure and smaller size.

[0047] In some embodiments of this application, the material of the radial stator poles 21 includes a magnetically permeable ferromagnetic material. A pair of radial stator poles 21 refers to two radial stator poles 21 that are symmetrical about the central axis Z.

[0048] In some embodiments of this application, the number of radial stator poles 21 can be more than three, preferably an even number greater than or equal to four, and they are evenly distributed around the rotor 10.

[0049] In some embodiments of this application, the absolute value of the difference between the height H1 of the rotor permanent magnet 12 and the height H2 of the radial stator pole 21 is less than or equal to 70% of the height H2 of the radial stator pole 21. That is, |H2-H1| / H2≤0.3.

[0050] In some embodiments of this application, reference is made to Figure 2 As shown, the radial stator pole 21 is in the shape of a "U". The concave part of the "U" faces the rotor 10 and forms a mounting groove. The stator coil 22 is wound in the mounting groove. The upper and lower axial sides of the mounting groove are defined as upper teeth and lower teeth, respectively.

[0051] In some embodiments of this application, the absolute value of the difference between the upper tooth height h1 and the lower tooth height h2 of the radial stator pole 21 is less than or equal to 80% of the lower tooth height h2. That is, |h1-h2| / h2≤0.8.

[0052] In some embodiments of this application, the ratio of the diameter D1 of the circle formed by the upper teeth of the at least two pairs of radial stator poles 21 to the diameter D2 of the circle formed by the lower teeth of the at least two pairs of radial stator poles 21 is less than or equal to 20%. That is, |D1-D2| / D2≤0.2.

[0053] In some other embodiments of this application, the radial stator pole 21 may also be in the shape of an "I", with the recesses on both sides of the "I" being mounting grooves.

[0054] In some embodiments of this application, the side of the radial stator pole 21 facing the rotor 10 may also be sequentially provided with a stator permanent magnet and a stator soft iron. In some embodiments of this application, the material of the stator permanent magnet includes neodymium iron boron. In some embodiments of this application, the material of the stator soft iron includes pure iron or silicon steel. The stator permanent magnet is magnetized radially along the rotor.

[0055] In some embodiments of this application, the stator coils 22 on the two radial stator poles of each pair of radial stator poles 21 are wound in opposite directions and connected in series. In other embodiments of this application, the stator coils 22 on the two radial stator poles of each pair of radial stator poles 21 are not necessarily connected in series; they can be connected to opposite currents, as long as the two radial stator poles of each pair of radial stator poles 21 can generate magnetic fields in opposite directions when current is connected.

[0056] In some embodiments of this application, the magnetic bearing 100 further includes: an active control system (not shown in the figures), configured to provide active stability control of the radial displacement of the rotor 10. The active control system includes: a displacement sensor for detecting the radial offset of the rotor 10; and a controller that receives the detection result of the displacement sensor and is configured to output a control current to the stator coil 24 to return the radial offset of the rotor 10 to within the offset threshold when the radial offset detected by the displacement sensor is greater than the offset threshold. As those skilled in the art will understand from this disclosure, the main control system can be applied to the magnetic bearing control in this application, and will not be described in detail here.

[0057] Figure 3 This is a schematic diagram illustrating the bias magnetic field principle based on the longitudinal section of the magnetic bearing in an embodiment of this application. It should be noted that, for the sake of simplicity, and to avoid the magnetic path overlapping with the label lines and affecting the visual appeal, Figure 3The designation of the magnetic bearing has been omitted; please refer to [reference needed]. Figure 2 .

[0058] refer to Figure 3 As shown, Figure 3 The magnetic path 30 shown is generated by the rotor permanent magnet 12 and the radial stator pole 21. It is mainly used to establish a static bias magnetic field. Since the rotor permanent magnet 12 is magnetized along the axial direction, the magnetic path between it and the radial stator pole 21 is short and the magnetic reluctance is low, so a high-intensity bias magnetic field can be established.

[0059] Figure 4 This is a schematic diagram of the axial passive control magnetic circuit based on the longitudinal section of the magnetic bearing described in this application embodiment.

[0060] refer to Figure 3 and Figure 4 As shown, the axial stiffness of rotor 10 is the passive axial stiffness provided by the bias magnetic field. When rotor 10 is in the axial equilibrium position ( Figure 3 As shown), due to the axial structural symmetry, rotor 10 is not subjected to axial force. When rotor 10 is subjected to a downward disturbance force ( Figure 4 As shown, rotor 10 is displaced downwards. At this time, the permanent magnetic force generated by the bias magnetic field will pull rotor 10 back to the equilibrium position.

[0061] Figure 5 This is a schematic diagram of the passive tilt control magnetic circuit based on the longitudinal section of the magnetic bearing in an embodiment of this application.

[0062] refer to Figure 3 and Figure 5 As shown, the roll stiffness of rotor 10 is the passive roll stiffness provided by the bias magnetic field. When rotor 10 is in the equilibrium position ( Figure 3 As shown), due to structural symmetry, the rotor shaft is not subjected to torque. When rotor 10 is disturbed, a deflection occurs along the central axis Z (along...). Figure 5 (Clockwise direction). At this time, the corresponding rotor permanent magnet and radial stator poles are misaligned, and the permanent magnetic force generated by the bias magnetic field produces a counterclockwise restoring torque, pulling the rotor 10 back to the equilibrium position.

[0063] Figure 6 This is a schematic diagram of the radial active control magnetic circuit of the magnetic bearing described in the embodiments of this application.

[0064] refer to Figure 3 and Figure 6 As shown, when rotor 10 is in the radial equilibrium position, due to the symmetry of the structure, the magnetic induction intensity generated by the bias magnetic field in the radial magnetic gap is equal in magnitude, and the resulting permanent magnet force is equal in the radial direction, so rotor 10 is in the equilibrium position (e.g. Figure 3(As shown). If rotor 10 is subjected to a rightward disturbance force, rotor 10 will deviate from its equilibrium position and shift to the right (e.g., Figure 6 As shown in the figure, the magnetic gap on the left is larger than that on the right. The magnetic induction intensity on the left decreases, while the magnetic induction intensity on the right increases. When the magnetic pole area is constant, the magnetic force is proportional to the square of the magnetic induction intensity. Therefore, the permanent magnet force generated by the bias magnetic field is greater on the right than on the left, and the rotor 10 cannot return to the equilibrium position on its own. At this time, a non-contact displacement sensor (not shown in the figure) arranged in the radial direction of the rotor 10 detects the offset of the rotor 10 relative to the radial equilibrium position and sends it to the controller. The controller converts the displacement signal into a control signal, which is then converted into a control current by a power amplifier and fed into the stator coils of the left and right radial stator poles, thereby generating the magnetic force as shown in the figure. Figure 6 The control magnetic field 40 is shown. The magnetic induction intensity generated by the control magnetic field is superimposed and enhanced in the radial magnetic gap on the left, and superimposed and weakened in the radial magnetic gap on the right. At this time, the magnetic force in the left magnetic gap will be greater than the magnetic force in the right magnetic gap, pulling the rotor 10 back as shown. Figure 3 The radial equilibrium position is shown.

[0065] The technical solution of this application utilizes an axially magnetized rotor permanent magnet 12 to provide a static bias magnetic field. The simple magnetic circuit of the rotor 10 and stator 20 results in low magnetic reluctance and higher radial active control efficiency compared to traditional magnetic levitation bearings, which greatly reduces the control current for radial active control and significantly reduces the overall system power consumption. Furthermore, the simple magnetic circuit, while ensuring sufficient passive control stiffness in the axial and tilt directions, results in a very simple system structure, significantly fewer components compared to traditional magnetic levitation bearings, greatly reducing system complexity and facilitating miniaturization.

[0066] The technical solution of this application only requires a single annular rotor permanent magnet 12 and a radial stator pole 21 made of magnetically conductive material to achieve efficient active and passive control. Compared with any current magnetic levitation bearing design, it greatly reduces the system complexity and makes the system extremely simple.

[0067] This application provides a magnetic bearing that makes the magnetic bearing structure more compact and simple, and can miniaturize the magnetic bearing without reducing its performance, thereby increasing the application prospects of the magnetic bearing.

[0068] Figure 7 This is a schematic diagram of the pump device according to an embodiment of this application.

[0069] Embodiments of this application also provide a pump device 200, see reference. Figure 7 As shown, it includes: a pump head housing 210; an impeller 220, the impeller being disposed inside the pump head housing 210 for pumping fluids, such as blood; and at least a portion of the magnetic bearing 100 as described above being disposed inside the pump head housing 210. Figure 7 As shown, the rotor 10 of the magnetic bearing 100 is disposed within the annular groove 211 defined by the pump head housing 210. As those skilled in the art will understand from this disclosure, the magnetic bearing 100 is configured to drive the impeller 220 to rotate about the central axis Z.

[0070] The pump device 200 described in this application embodiment is, for example, a centrifugal blood pump.

[0071] The structure of the magnetic bearing 100 has been described in detail previously and will not be repeated here.

[0072] Continue to refer to Figure 7 The pump device 200 further includes a drive device, such as a drive motor 230, for providing rotational force to the magnetic bearing 100, and at least a portion of the drive motor 230, for example, near one end of the rotor 10, extends into and is surrounded by the rotor 10, outside the annular groove 211 defined by the pump head housing 210 for receiving the rotor 10.

[0073] Continue to refer to Figure 7 The pump assembly 200 further includes a pump housing 240 for accommodating at least a portion of the drive motor 230 and the magnetic bearing 100, such as... Figure 7 As shown, the pump housing 240 houses the stator 20 such that the stator 20 surrounds the pump head housing 210 with an annular groove 211 for accommodating the rotor 10. The pump head housing 210 is detachably connected to the pump housing 240. The pump housing 240 contains a pump head seat 241 for accommodating at least a portion of the pump head housing 210, and at least a portion of the pump head seat 241 has a shape complementary to at least a portion of the pump head housing 210.

[0074] In the technical solution of this application, after simplifying the magnetic bearing structure, the magnetic bearing structure is more compact and concise, which makes the magnetic bearing smaller and can also improve the service life of the pump device.

[0075] This application provides a magnetic bearing and a pump device. The magnetic bearing has a more compact and simple structure, and the magnetic bearing can be miniaturized without reducing its performance, thereby increasing the application prospects of the magnetic bearing. For example, it can be applied to the field of artificial hearts where rotation and size requirements are extremely high, such as the centrifugal blood pump mentioned above.

[0076] In summary, after reading this application, those skilled in the art will understand that the foregoing application content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.

[0077] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element.

[0078] As used in this embodiment, the terms "permanent magnet" or "magnet" refer to a component made of a ferromagnetic material with high remanence and coercivity, and magnetized to serve as a source of a magnetic field, such as NeFeB, as is known to those skilled in the art. As used herein, "soft iron" refers to a component made of laminated or non-laminated ferromagnetic material with low remanence and coercivity, and used to guide magnetic flux, such as pure iron, silicon steel, or Hiperco alloys, as is known to those skilled in the art.

[0079] It should also be understood that the terms “comprising,” “containing,” “including,” or “comprise”, when used in this application, indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof.

[0080] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.

[0081] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Therefore, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. Thus, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

Claims

1. A magnetic bearing, characterized in that, include: A rotor and a stator, the stator being arranged circumferentially around the rotor, the stator being configured to provide passive stability control with respect to the axial and tilt displacements of the rotor and active stability control with respect to the radial displacement; The rotor has a central axis and is a rotor permanent magnet; The stator includes: at least two pairs of radial stator poles, which are uniformly distributed along the circumference of the rotor and are not magnetically connected to each other; and stator coils, which are wound around each of the at least two pairs of radial stator poles. The ratio of the outer diameter of the rotor to the axial height of the rotor is greater than or equal to 1.5; the ratio of the outer diameter to the inner diameter of the rotor is greater than or equal to 1.1; the absolute value of the difference between the height of the rotor permanent magnet and the height of the radial stator pole is less than or equal to 70% of the height of the radial stator pole; the distance between the rotor and the stator is less than or equal to 10% of the outer diameter of the rotor; the rotor is an integral ring and is made of only one type of permanent magnet material.

2. The magnetic bearing as described in claim 1, characterized in that, Also includes: An active control system, configured to provide active stability control with respect to the radial displacement of the rotor, the active control system comprising: A displacement sensor is used to detect the radial offset of the rotor; The controller receives the detection result of the displacement sensor and is configured to output a control current to the stator coil when the radial offset detected by the displacement sensor is greater than the offset threshold, so that the radial offset of the rotor returns to within the offset threshold.

3. The magnetic bearing as described in claim 1, characterized in that, The rotor permanent magnet is magnetized along the direction of the central axis.

4. The magnetic bearing as described in claim 1, characterized in that, The radial stator poles are in the shape of a concave "U". The concave part of the "U" faces the rotor and forms a mounting groove. The stator coils are wound in the mounting groove. The upper and lower axial sides of the mounting groove are defined as upper teeth and lower teeth, respectively.

5. The magnetic bearing as described in claim 4, characterized in that, The ratio of the absolute value of the difference between the upper and lower tooth heights of the radial stator pole to the lower tooth height is less than or equal to 80%.

6. The magnetic bearing as described in claim 4, characterized in that, The ratio of the diameter of the circle formed by the upper teeth of the at least two pairs of radial stators to the diameter of the circle formed by the lower teeth of the at least two pairs of radial stators is less than or equal to 20%.

7. The magnetic bearing as claimed in claim 1, characterized in that, The rotor permanent magnet is made of neodymium iron boron, and / or the radial stator poles are made of a magnetically conductive ferromagnetic material.

8. A pump device, characterized in that, include: Pump head housing; An impeller is disposed inside the pump head housing; The magnetic bearing as described in any one of claims 1 to 7, wherein the rotor of the magnetic bearing is disposed inside the pump head housing, and the magnetic bearing is configured to drive the impeller to rotate about the central axis.

9. The pump device as claimed in claim 8, characterized in that, The pump device includes: Pump casing; A drive unit, disposed inside the pump housing, is used to provide rotational force to the magnetic bearing; The stator of the magnetic bearing is disposed inside the pump housing, and the pump head housing is detachably connected to the pump housing.

10. The pump device as claimed in claim 9, characterized in that, The rotor of the magnetic bearing is disposed within the annular groove defined by the pump head housing. The drive device is close to one end of the rotor, extends into the space defined by the annular groove of the pump head housing for accommodating the rotor, and is surrounded by the rotor.

11. The pump device as claimed in claim 10, characterized in that, The stator is arranged around the annular groove of the pump head housing for accommodating the rotor, and the pump housing is provided with a pump head seat for accommodating at least a portion of the pump head housing, wherein at least a portion of the pump head seat has a complementary shape to at least a portion of the pump head housing.

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