Hybrid magnetic bearing sealed by magnetic fluid

Abstract

The invention provides a magnetic fluid sealed hybrid magnetic bearing, which comprises a base, a magnetic bearing assembly, a displacement sensor and a protective bearing assembly, and is characterized in that the magnetic bearing assembly comprises an active control side stator, a permanent magnet ring, a magnetic conductive ring pole shoe, a control coil, a radial magnetic bearing rotor lamination and a rotor; the control coil is used for pulling the rotor back to the balance position when the rotor is not located at the balance position, a magnetofluid spiral groove is formed in the end of the rotor, magnetofluid is arranged between the magnetofluid spiral groove of the rotor and the magnetic conductive ring pole shoe, and the magnetofluid spiral groove is used for achieving rotating shaft dynamic sealing of the magnetofluid. The permanent magnet ring is used for providing an external constant magnetic field for the magnetic fluid and providing permanent magnet bias magnetic flux between the active control side stator and the radial magnetic bearing rotor lamination; and the magnetic conductive ring pole shoes are used as control pole shoes of the magnetic fluid and a permanent magnet bias magnetic circuit of the closed hybrid magnetic bearing. By means of the technical scheme, the technical problem that in the prior art, the axial length of a magnetofluid sealing magnetic bearing is too long is solved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic fluid sealing, and in particular to a hybrid magnetic bearing sealed with magnetic fluid. Background Art

[0002] Magnetic fluid, also known as magnetic liquid or ferromagnetic fluid, has both the magnetism of solid magnetic materials and the fluidity of liquids. It is a solid-liquid two-phase colloidal material made of nano-scale magnetic solid particles, base carrier liquid and surfactant. The fluid will only show magnetism when an external magnetic field is applied. It has good fluidity, lubricity and sealing properties. Through the action of appropriate magnetic fields, the magnetic fluid can fill the annular space and establish a series of "O-rings" to achieve a sealing effect.

[0003] Hybrid magnetic bearings are also called permanent magnet biased magnetic bearings, or hybrid magnetic bearings for short. The coil windings of hybrid magnetic bearings only supply control current and do not need to provide bias current. Therefore, compared with electromagnetic bearings, they have the advantages of low power consumption, low heat generation, small size, short axial length, and fewer power amplifiers required. Figure 3 The permanent magnetic circuit of the permanent magnetic biased radial two-degree-of-freedom magnetic bearing represented by is relatively independent, and the permanent magnetic conductive ring only plays the role of closing the permanent magnetic circuit.

[0004] At present, magnetic bearing machinery uses magnetic fluid seals mainly in a split arrangement and parallel arrangement, which occupies a long axial length and is not conducive to improving the rotor's maximum speed. Summary of the invention

[0005] The invention provides a magnetic fluid sealed hybrid magnetic bearing, which can solve the technical problem of excessively long axial length of the magnetic fluid sealed magnetic bearing in the prior art.

[0006] According to one aspect of the present invention, a hybrid magnetic bearing sealed by a magnetic fluid is provided, and the hybrid magnetic bearing sealed by a magnetic fluid comprises: a base; a magnetic bearing assembly, and the magnetic bearing assembly comprises an active control side stator, a permanent magnet ring, a magnetic conductive ring pole shoe, a control coil, a radial magnetic bearing rotor lamination and a rotor, wherein the radial magnetic bearing rotor lamination is sleeved on the rotor, the active control side stator is fixedly arranged in the base, the radial magnetic bearing rotor lamination is arranged in the active control side stator and is coaxially arranged with the active control side stator, the control coil is wound on the magnetic pole of the active control side stator, and the control coil is used to pass current to generate magnetic force to pull the rotor back to the equilibrium position when the rotor is not in a balanced position, the permanent magnet ring and the magnetic conductive ring pole shoe are both arranged in the base, one side of the permanent magnet ring is in contact with the active control side stator, and the other side of the permanent magnet ring is in contact with the magnetic conductive ring pole shoe, and the end of the rotor has a magnetic fluid spiral groove, and the magnetic fluid spiral groove of the rotor and the magnetic conductive ring pole shoe are in contact with each other. A magnetic fluid is arranged between the shoes, and the magnetic fluid spiral groove is used to realize the dynamic sealing of the rotating shaft of the magnetic fluid. The magnetic ring pole shoe and the permanent magnet ring are both arranged coaxially with the rotor. The permanent magnet ring is used to provide an external constant magnetic field to the magnetic fluid and provide a permanent magnetic bias flux between the active control side stator and the radial magnetic bearing rotor laminations. The magnetic ring pole shoe is used to act as a control pole shoe of the magnetic fluid and a permanent magnetic bias magnetic circuit of the closed hybrid magnetic bearing; the displacement sensor, the displacement sensor includes a displacement sensor stator and a sensor rotor lamination, the sensor rotor lamination is sleeved on the rotor, the displacement sensor stator is arranged in the base and is coaxial with the rotor, the displacement sensor stator and the sensor rotor lamination work together to output a rotor radial displacement signal; the protective bearing assembly, the protective bearing assembly is arranged on the base, the rotor is rotatably arranged on the protective bearing assembly, and the protective bearing assembly is used to provide temporary support to the rotor at the start and stop moments of the magnetic bearing assembly and when it fails.

[0007] Furthermore, the base includes a magnetic bearing seat and a casing, the magnetic bearing seat is fixedly connected to the casing, the magnetic bearing assembly is arranged in the magnetic bearing seat, the displacement sensor stator is fixedly connected to the magnetic bearing seat, and the protective bearing assembly is fixedly connected to the casing.

[0008] Furthermore, the protective bearing assembly includes a protective bearing and a protective bearing seat, the protective bearing seat is fixedly connected to the casing, the protective bearing is arranged in the protective bearing seat, and the rotor is rotatably arranged in the protective bearing.

[0009] Furthermore, the active control-side stator includes an 8-pole structure, a 3-pole structure, a 4-pole structure, a 6-pole structure or a 12-pole structure.

[0010] Furthermore, the active control side stator and radial magnetic bearing rotor laminations are both made of laminated silicon steel sheets.

[0011] Furthermore, the permanent magnet ring is sintered from neodymium iron boron material.

[0012] Furthermore, the material of the magnetic ring pole shoe includes electrical pure iron.

[0013] The technical scheme of the present invention is applied to provide a hybrid magnetic bearing sealed by magnetic fluid. The hybrid magnetic bearing adopts a magnetic ring pole shoe as a hybrid magnetic bearing magnetic ring. The end of the rotor has a magnetic fluid spiral groove, which can drive the magnetic fluid to be transported in the vacuum direction when the rotor rotates. The spiral seal used in the hybrid magnetic bearing is a non-contact shaft dynamic sealing device, which adopts fluid dynamic pressure reverse transmission. When the shaft rotates, the spiral groove on the surface of the rotor plays a pumping role on the magnetic fluid in the narrow gap, converting the rotational kinetic energy of the spiral groove into the pressure energy of the magnetic fluid, thereby improving the sealing vacuum degree and shortening the axial occupied length of the magnetic fluid sealing structure. Compared with the conventional situation of only using spirals for sealing in the prior art, the sealing effect is not good when the shaft speed is low. The present invention combines magnetic fluid seals and spiral seals for sealing, which can solve the failure problem of magnetic fluid seals at higher speeds and the leakage problem of spiral seals when parking and slow speeds, and achieve a more stable sealing effect at different speeds. Through appropriate size setting, it can meet the requirements of almost not affecting the control of the hybrid magnetic bearing, and at the same time play a good sealing effect, solving the problem of excessive axial length of magnetic fluid sealed magnetic bearings. Therefore, compared with the prior art, the hybrid magnetic bearing with magnetic fluid seal provided by the present invention cleverly uses the magnetic poles of the permanent magnetic circuit of the hybrid magnetic bearing as magnetic fluid pole shoes. Through appropriate size setting, it can meet the requirement of almost not affecting the control of the hybrid magnetic bearing, while achieving a good sealing effect; at the same time, a spiral groove is opened on the surface of the rotor, and the spiral groove has a pumping effect on the liquid in the narrow gap formed between the rotating shaft and the stator, converting the rotational kinetic energy of the spiral groove into the pressure energy of the liquid, thereby preventing the sealed liquid from leaking, and effectively solving the problem of the excessive axial length of the magnetic fluid sealed magnetic bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 The overall structural schematic diagram of a hybrid magnetic bearing sealed by magnetic fluid provided according to a specific embodiment of the present invention is shown;

[0016] Figure 2 A schematic diagram of a magnetic circuit provided according to a specific embodiment of the present invention is shown;

[0017] Figure 3A schematic structural diagram of a magnetic bearing assembly provided according to a specific embodiment of the present invention is shown;

[0018] Figure 4a and Figure 4b A three-dimensional schematic diagram of a magnetic circuit of a magnetic bearing assembly provided according to a specific embodiment of the present invention is shown;

[0019] Figure 5 A schematic diagram of the cooperation between a magnetic fluid sealing pole shoe and a magnetic fluid spiral groove provided according to a specific embodiment of the present invention is shown.

[0020] The above drawings include the following reference numerals:

[0021] 10. Base; 11. Magnetic bearing seat; 12. Casing; 20. Magnetic bearing assembly; 21. Active control side stator; 22. Permanent magnet ring; 23. Magnetic ring pole shoe; 24. Control coil; 25. Radial magnetic bearing rotor lamination; 26. Rotor; 26a. Magnetic fluid spiral groove; 30. Displacement sensor; 31. Displacement sensor stator; 32. Sensor rotor lamination; 40. Protective bearing assembly; 41. Protective bearing; 42. Protective bearing seat. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of 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 in 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.

[0023] 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.

[0024] 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.

[0025] like Figures 1 to 5As shown, according to a specific embodiment of the present invention, a hybrid magnetic bearing sealed by a magnetic fluid is provided, and the hybrid magnetic bearing sealed by a magnetic fluid includes a base 10, a magnetic bearing assembly 20, a displacement sensor 30 and a protective bearing assembly 40, and the magnetic bearing assembly 20 includes an active control side stator 21, a permanent magnet ring 22, a magnetic ring pole shoe 23, a control coil 24, a radial magnetic bearing rotor lamination 25 and a rotor 26, the radial magnetic bearing rotor lamination 25 is sleeved on the rotor 26, the active control side stator 21 is fixedly arranged in the base 10, and the radial magnetic bearing rotor The lamination 25 is arranged in the active control side stator 21 and is coaxially arranged with the active control side stator 21. The control coil 24 is wound on the magnetic pole of the active control side stator 21. The control coil 24 is used to pass current to generate magnetic force to pull the rotor back to the equilibrium position when the rotor 26 is not in the equilibrium position. The permanent magnet ring 22 and the magnetic ring pole shoe 23 are both arranged in the base 10. One side of the permanent magnet ring 22 is in contact with the active control side stator 21, and the other side of the permanent magnet ring 22 is in contact with the magnetic ring pole shoe 23. The end of the rotor 26 has a magnetic fluid spiral groove. 26a, a magnetic fluid is arranged between the magnetic fluid spiral groove 26a of the rotor and the magnetic ring pole shoe 23, the magnetic fluid spiral groove 26a is used to realize the dynamic sealing of the rotating shaft of the magnetic fluid, the magnetic ring pole shoe 23 and the permanent magnet ring 22 are coaxially arranged with the rotor 26, the permanent magnet ring 22 is used to provide an external constant magnetic field to the magnetic fluid and provide a permanent magnetic bias flux between the active control side stator 21 and the radial magnetic bearing rotor lamination 25, the magnetic ring pole shoe 23 is used to serve as the control pole shoe of the magnetic fluid and close the permanent magnetic bias magnetic circuit of the hybrid magnetic bearing; displacement sensor 30 It includes a displacement sensor stator 31 and a sensor rotor lamination 32. The sensor rotor lamination 32 is sleeved on the rotor 26. The displacement sensor stator 31 is arranged in the base 10 and is coaxially arranged with the rotor 26. The displacement sensor stator 31 and the sensor rotor lamination 32 work together to output a rotor radial displacement signal; the protective bearing assembly 40 is arranged on the base 10, and the rotor 26 is rotatably arranged on the protective bearing assembly 40. The protective bearing assembly 40 is used to provide temporary support for the rotor 26 when the magnetic bearing assembly 20 starts and stops and when it fails.

[0026] By using this configuration, a hybrid magnetic bearing sealed with magnetic fluid is provided. The hybrid magnetic bearing adopts a magnetic ring pole shoe as a hybrid magnetic bearing magnetic ring. The end of the rotor has a magnetic fluid spiral groove, which can drive the magnetic fluid to be transported in the vacuum direction when the rotor rotates. The spiral seal used in the hybrid magnetic bearing is a non-contact shaft dynamic sealing device, which adopts fluid dynamic pressure reverse transmission. When the shaft rotates, the spiral groove on the surface of the rotor plays a pumping role on the magnetic fluid in the narrow gap, converting the rotational kinetic energy of the spiral groove into the pressure energy of the magnetic fluid, thereby improving the sealing vacuum degree and shortening the axial occupied length of the magnetic fluid sealing structure. Compared with the conventional situation in the prior art where only the spiral is used for sealing, the sealing effect is not good when the shaft speed is low. The present invention combines the magnetic fluid seal and the spiral seal for sealing, which can solve the failure problem of the magnetic fluid seal at a higher speed and the leakage problem of the spiral seal at parking and low speed, and achieve a more stable sealing effect at different speeds. Through appropriate size setting, it can meet the requirement of almost not affecting the control of the hybrid magnetic bearing, and at the same time play a good sealing effect, solving the problem of the excessive axial length of the magnetic fluid sealed magnetic bearing. Therefore, compared with the prior art, the hybrid magnetic bearing with magnetic fluid seal provided by the present invention cleverly uses the magnetic poles of the permanent magnetic circuit of the hybrid magnetic bearing as magnetic fluid pole shoes. Through appropriate size setting, it can meet the requirement of almost not affecting the control of the hybrid magnetic bearing, while achieving a good sealing effect; at the same time, a spiral groove is opened on the surface of the rotor, and the spiral groove has a pumping effect on the liquid in the narrow gap formed between the rotating shaft and the stator, converting the rotational kinetic energy of the spiral groove into the pressure energy of the liquid, thereby preventing the sealed liquid from leaking, and effectively solving the problem of the excessive axial length of the magnetic fluid sealed magnetic bearing.

[0027] Furthermore, in the present invention, in order to facilitate the installation of the magnetic bearing assembly, the displacement sensor and the protective bearing assembly and the radial sealing protection, the base 10 can be configured to include a magnetic bearing seat 11 and a housing 12, the magnetic bearing seat 11 is fixedly connected to the housing 12, the magnetic bearing assembly 20 is arranged in the magnetic bearing seat 11, the displacement sensor stator 31 is fixedly connected to the magnetic bearing seat 11, and the protective bearing assembly 40 is fixedly connected to the housing 12.

[0028] In addition, in the present invention, in order to provide temporary support for the rotor 26 at the start-up and shutdown moments and when the hybrid magnetic bearing fails, the protective bearing assembly 40 can be configured to include a protective bearing 41 and a protective bearing seat 42, the protective bearing seat 42 is fixedly connected to the casing 12, the protective bearing 41 is disposed in the protective bearing seat 42, and the rotor 26 is rotatably disposed in the protective bearing 41.

[0029] As a specific embodiment of the present invention, the active control-side stator 21 includes an 8-pole structure, a 3-pole structure, a 4-pole structure, a 6-pole structure or a 12-pole structure.

[0030] In addition, in the present invention, in order to reduce eddy current loss, the active control side stator 21 and the radial magnetic bearing rotor lamination 25 are both made of silicon steel sheets. The silicon steel sheet has an extremely low carbon content and a silicon content of up to 0.5%-4.5%. The silicon element makes it have good electromagnetic properties, which are specifically manifested in its low core loss, high magnetic permeability, low coercive force and low magnetic aging. At the same time, it has good processing performance, high stacking coefficient and good punching performance. As a specific embodiment of the present invention, the active control side stator 21 and the radial magnetic bearing rotor lamination 25 provided by the present invention both use 0.35mm silicon steel sheets, and their magnetic induction intensity is below 1.4T in the linear region, and the saturation magnetic induction intensity is 1.7T. This is only a preferred embodiment. The active control side stator 21 and the radial magnetic bearing rotor lamination 25 can also use other ferromagnetic materials according to actual use. As other embodiments of the present invention, if the load is relatively constant and the control current is almost unchanged during actual use, the active control side stator 21 can also use a whole block of high magnetic permeability material, and the radial magnetic bearing rotor lamination can also be omitted.

[0031] Furthermore, in the present invention, the permanent magnet ring 22 is sintered with NdFeB permanent magnet material (existing material), which is a tetragonal crystal formed by neodymium, iron and boron, has a high magnetic energy product and excellent magnetic properties, and is widely used in the fields of electric machinery, electronics, etc. This structure uses a permanent magnet material of model N35EH, with a maximum magnetic energy product of 287kJ / m 3 , the maximum operating temperature is 200°C. If the annular area is large and the magnetization is uneven, it can also be made of small permanent magnets. This is only a preferred embodiment, and the permanent magnet ring 22 can also use other permanent magnet materials according to actual use.

[0032] In addition, in the present invention, in order to ensure the magnetic conductivity of the magnetic ring pole shoe, the material of the magnetic ring pole shoe 23 includes electrical pure iron. Electrical pure iron is also called industrial pure iron, which is a high-quality steel with an iron content greater than 99.5%, low carbon, low sulfur, and low phosphorus iron. It has good electromagnetic properties, which are specifically manifested in high saturation magnetic induction intensity, low coercive force, high magnetic permeability, stable magnetism and no magnetic aging, and low price and good hot and cold processing performance. It is widely used in related parts with electromagnet structure. As a specific embodiment of the present invention, this structure uses electrical pure iron of model DT4C, whose magnetic induction intensity is below 1.5T in its linear region, and the saturation magnetic induction intensity is 1.8T. This is only a preferred embodiment, and the magnetic ring pole shoe 23 can also use other ferromagnetic materials according to actual use.

[0033] In order to further understand the present invention, the following Figures 1 to 5 The hybrid magnetic bearing with magnetic fluid seal provided by the present invention is described in detail.

[0034] like Figures 1 to 5As shown, according to a specific embodiment of the present invention, a hybrid magnetic bearing sealed by a magnetic fluid is provided, and the hybrid magnetic bearing sealed by a magnetic fluid includes a base 10, a magnetic bearing assembly 20, a displacement sensor 30 and a protective bearing assembly 40, and the magnetic bearing assembly 20 includes an active control side stator 21, a permanent magnet ring 22, a magnetic ring pole shoe 23, a control coil 24, a radial magnetic bearing rotor lamination 25 and a rotor 26, the radial magnetic bearing rotor lamination 25 is sleeved on the rotor 26, the active control side stator 21 is fixedly arranged in the base 10, and the radial magnetic bearing rotor The lamination 25 is arranged in the active control side stator 21 and is coaxially arranged with the active control side stator 21. The control coil 24 is wound on the magnetic pole of the active control side stator 21. The control coil 24 is used to pass current to generate magnetic force to pull the rotor back to the equilibrium position when the rotor 26 is not in the equilibrium position. The permanent magnet ring 22 and the magnetic ring pole shoe 23 are both arranged in the base 10. One side of the permanent magnet ring 22 is in contact with the active control side stator 21, and the other side of the permanent magnet ring 22 is in contact with the magnetic ring pole shoe 23. The end of the rotor 26 has a magnetic fluid spiral groove. 26a, a magnetic fluid is arranged between the magnetic fluid spiral groove 26a of the rotor and the magnetic ring pole shoe 23, the magnetic fluid spiral groove 26a is used to realize the dynamic sealing of the rotating shaft of the magnetic fluid, the magnetic ring pole shoe 23 and the permanent magnet ring 22 are coaxially arranged with the rotor 26, the permanent magnet ring 22 is used to provide an external constant magnetic field to the magnetic fluid and provide a permanent magnetic bias flux between the active control side stator 21 and the radial magnetic bearing rotor lamination 25, the magnetic ring pole shoe 23 is used to serve as the control pole shoe of the magnetic fluid and close the permanent magnetic bias magnetic circuit of the hybrid magnetic bearing; displacement sensor 30 The sensor rotor lamination 32 includes a displacement sensor stator 31 and a sensor rotor lamination 32, wherein the sensor rotor lamination 32 is sleeved on the rotor 26, the displacement sensor stator 31 is arranged in the base 10 and is arranged coaxially with the rotor 26, and the displacement sensor stator 31 and the sensor rotor lamination 32 work together to output a rotor radial displacement signal; the protective bearing assembly 40 is arranged on the base 10, and the rotor 26 is rotatably arranged on the protective bearing assembly 40, and the protective bearing assembly 40 is used to provide temporary support for the rotor 26 at the start and stop moments of the magnetic bearing assembly 20 and when it fails. The base 10 includes a magnetic bearing seat 11 and a housing 12, wherein the magnetic bearing seat 11 is fixedly connected to the housing 12, the magnetic bearing assembly 20 is arranged in the magnetic bearing seat 11, the displacement sensor stator 31 is fixedly connected to the magnetic bearing seat 11, and the protective bearing assembly 40 is fixedly connected to the housing 12. The protective bearing assembly 40 includes a protective bearing 41 and a protective bearing seat 42 . The protective bearing seat 42 is fixedly connected to the housing 12 . The protective bearing 41 is disposed in the protective bearing seat 42 . The rotor 26 is rotatably disposed in the protective bearing 41 .

[0035] The magnetic bearing assembly 20 controls radial two-degree-of-freedom suspension, the displacement sensor 30 outputs a radial displacement signal of the rotor, and the protective bearing assembly 40 provides temporary support for the rotor after the magnetic suspension bearing fails, protecting the shaft system from damage.

[0036] In this embodiment, the active control side stator 21 is an 8-pole structure, each pole is wound with a coil of a designed number of turns, and the coils in the same direction are connected in series to the magnetic bearing controller, for example Figure 4a The four magnetic poles with marked polarity are used to control the Y direction. The two upper magnetic poles have the same polarity, the two lower magnetic poles have the same polarity, and the upper and lower polarities are opposite. Figure 4a The four magnetic poles whose polarity is not marked are used to control the X direction. The active control side stator 21 and the radial magnetic bearing rotor laminations 25 are made of laminated silicon steel sheets to reduce eddy current losses. Silicon steel sheets have extremely low carbon content and silicon content of up to 0.5%-4.5%. The silicon element gives them good electromagnetic properties, which are specifically manifested in their low core loss, high magnetic permeability, low coercive force and low magnetic aging. At the same time, they have good processing performance, high stacking coefficient and good punching properties. This structure uses 0.35mm silicon steel sheets, whose magnetic induction intensity is below 1.4T in the linear region, and the saturation magnetic induction intensity is 1.7T.

[0037] The permanent magnet ring 22 is axially magnetized and sintered with neodymium iron boron material, which is a tetragonal crystal formed by neodymium, iron and boron, with high magnetic energy product and excellent magnetic properties, and is widely used in the fields of power machinery, electronics, etc. This structure uses permanent magnet material model N35EH, with a maximum magnetic energy product of 287kJ / m 3 , the maximum operating temperature is 200 ° C. If the annular area is large and the magnetization is uneven, it can also be made of small permanent magnets.

[0038] The magnetic ring pole shoe 23 plays the role of closing the permanent magnetic circuit in the magnetic bearing assembly, and is a magnetic shoe in the magnetic fluid sealing structure. Electrical pure iron with good magnetic conductivity is used. Electrical pure iron, also known as industrial pure iron, is a high-quality steel with an iron content greater than 99.5%, low carbon, low sulfur, and low phosphorus iron. It has good electromagnetic properties, specifically high saturation magnetic induction intensity, low coercive force, high magnetic permeability, stable magnetism and no magnetic aging, and low price, good cold and hot processing performance, and is widely used in related parts with electromagnet structure. This structure uses electrical pure iron of model DT4C, whose magnetic induction intensity is below 1.5T in its linear region, and the saturation magnetic induction intensity is 1.8T.

[0039] In this embodiment, the active control side stator 21 is an 8-pole structure. As other embodiments of the present invention, the active control side stator 21 can also be transformed into a 3-pole, 4-pole, 6-pole, 12-pole structure, etc., with similar principles. The material is not limited to silicon steel sheets. If the load is relatively constant and the control current is almost unchanged in actual use, a large block material with high magnetic conductivity can be selected.

[0040] Hybrid magnetic bearing magnetic circuit Figure 2 and Figure 3As shown, the solid line is the permanent magnetic bias flux generated by the permanent magnet, and the dotted line is the control flux generated by the control coil. Its working principle is: at the equilibrium position, the bias flux generated by the permanent magnet is the same in each air gap, the control flux is 0, and the resultant force on the rotor is 0; when the rotor undergoes radial displacement (taking the y+ direction as an example), the upper air gap decreases and the lower air gap increases. The control coil applies current to weaken the superposition of the permanent magnetic flux and the control flux in the upper air gap, and strengthen the superposition of the permanent magnetic flux and the control flux in the lower air gap, generating a downward resultant force on the rotor, pulling the rotor back to the equilibrium position.

[0041] Magnetic fluid seals Figure 5 As shown, the pole shoe is a hybrid magnetic bearing magnetic ring, and a screw structure is used on the rotor, which can drive the magnetic fluid to the vacuum direction when the rotor rotates. The spiral seal used in this structure is a non-contact shaft dynamic seal device that uses fluid dynamic pressure reverse transmission. When the shaft rotates, the spiral groove on the surface of the rotor pumps the magnetic fluid in the narrow gap, converting the rotational kinetic energy of the spiral groove into the pressure energy of the magnetic fluid, thereby improving the sealing vacuum and shortening the axial length occupied by the magnetic fluid sealing structure.

[0042] In summary, the present invention provides a hybrid magnetic bearing sealed with magnetic fluid. Compared with the prior art, the hybrid magnetic bearing cleverly uses the magnetic poles of the permanent magnetic circuit of the hybrid magnetic bearing as magnetic fluid pole shoes. Through appropriate size setting, it can meet the requirement of almost not affecting the control of the hybrid magnetic bearing, while achieving a good sealing effect; at the same time, a spiral groove is opened on the surface of the rotor, and the spiral groove has a pumping effect on the liquid in the narrow gap formed between the rotating shaft and the stator, and the rotational kinetic energy of the spiral groove is converted into the pressure energy of the liquid, thereby preventing the sealed liquid from leaking, and effectively solving the problem of the excessive axial length of the magnetic fluid sealed magnetic bearing.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hybrid magnetic bearing sealed by magnetic fluid, characterized in that: The hybrid magnetic bearing of the magnetic fluid seal comprises: Base (10); A magnetic bearing assembly (20), the magnetic bearing assembly (20) comprising an active control side stator (21), a permanent magnet ring (22), a magnetic ring pole shoe (23), a control coil (24), a radial magnetic bearing rotor lamination (25) and a rotor (26), the radial magnetic bearing rotor lamination (25) being sleeved on the rotor (26), the active control side stator (21) being fixedly arranged in the base (10), the radial magnetic bearing rotor lamination (25) being arranged in the active control side stator (21) and being coaxially arranged with the active control side stator (21), the control coil (24) being wound around the magnetic pole of the active control side stator (21), the control coil (24) being used for passing current to generate magnetic force to pull the rotor back to the equilibrium position when the rotor (26) is not in an equilibrium position, the permanent magnet ring (22) and the magnetic ring pole shoe (23) being arranged in the base (10), and the radial magnetic bearing rotor lamination (25) being sleeved on the rotor (26), the active control side stator (21) being fixedly arranged in the base (10), the radial magnetic bearing rotor lamination (25) being arranged in the active control side stator (21) and being coaxially arranged with the active control side stator (21), the control coil (24) being wound around the magnetic pole of the active control side stator (21), the control coil (24) being used for passing current to generate magnetic force to pull the rotor back to the equilibrium position when the rotor (26) is not in an equilibrium position, and the permanent magnet ring (22) and the magnetic ring pole shoe (23) are both arranged in the base (10). In the seat (10), one side of the permanent magnet ring (22) is in contact with the active control side stator (21), and the other side of the permanent magnet ring (22) is in contact with the magnetic ring pole shoe (23). The end of the rotor (26) has a magnetic fluid spiral groove (26a), and magnetic fluid is arranged between the magnetic fluid spiral groove (26a) of the rotor and the magnetic ring pole shoe (23). The magnetic fluid spiral groove (26a) is used to realize the dynamic sealing of the rotating shaft of the magnetic fluid. The magnetic ring pole shoe (23) and the permanent magnet ring (22) are both coaxially arranged with the rotor (26). The permanent magnet ring (22) is used to provide an external constant magnetic field to the magnetic fluid and provide a permanent magnetic bias flux between the active control side stator (21) and the radial magnetic bearing rotor lamination (25). The magnetic ring pole shoe (23) is used to serve as a control pole shoe of the magnetic fluid and close the permanent magnetic bias magnetic circuit of the hybrid magnetic bearing. A displacement sensor (30), the displacement sensor (30) comprising a displacement sensor stator (31) and a sensor rotor lamination (32), the sensor rotor lamination (32) being sleeved on the rotor (26), the displacement sensor stator (31) being arranged in the base (10) and coaxially arranged with the rotor (26), the displacement sensor stator (31) and the sensor rotor lamination (32) acting together to output a rotor radial displacement signal; A protective bearing assembly (40), wherein the protective bearing assembly (40) is arranged on the base (10), and the rotor (26) is rotatably arranged on the protective bearing assembly (40), and the protective bearing assembly (40) is used to provide temporary support for the rotor (26) at the start and stop moments of the magnetic bearing assembly (20) and when it fails.

2. The magnetic fluid sealed hybrid magnetic bearing according to claim 1, characterized in that: The base (10) comprises a magnetic bearing seat (11) and a casing (12); the magnetic bearing seat (11) is fixedly connected to the casing (12); the magnetic bearing assembly (20) is arranged in the magnetic bearing seat (11); the displacement sensor stator (31) is fixedly connected to the magnetic bearing seat (11); and the protective bearing assembly (40) is fixedly connected to the casing (12).

3. The magnetic fluid sealed hybrid magnetic bearing according to claim 2, characterized in that: The protective bearing assembly (40) comprises a protective bearing (41) and a protective bearing seat (42); the protective bearing seat (42) is fixedly connected to the housing (12); the protective bearing (41) is arranged in the protective bearing seat (42); and the rotor (26) is rotatably arranged in the protective bearing (41).

4. The magnetic fluid sealed hybrid magnetic bearing according to any one of claims 1 to 3, characterized in that: The active control side stator (21) comprises an 8-pole structure, a 3-pole structure, a 4-pole structure, a 6-pole structure or a 12-pole structure.

5. The magnetic fluid sealed hybrid magnetic bearing according to claim 4, characterized in that: The active control side stator (21) and the radial magnetic bearing rotor laminations (25) are both made of laminated silicon steel sheets.

6. The magnetic fluid sealed hybrid magnetic bearing according to claim 5, characterized in that: The permanent magnet ring (22) is sintered from neodymium iron boron material.

7. The magnetic fluid sealed hybrid magnetic bearing according to claim 6, characterized in that: The material of the magnetic conductive ring pole shoe (23) includes electrical pure iron.

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