Hybrid magnetic bearing with magnetic fluid seal

Abstract

The application provides a magnetic fluid sealed hybrid magnetic bearing, which comprises a base, a magnetic bearing assembly, a displacement sensor and a protection bearing assembly, 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 laminated sheet and a rotor, the control coil is used for pulling the rotor back to a balance position when the rotor is not in the balance position, the end of the rotor is provided with a magnetic fluid spiral groove, a magnetic fluid is arranged between the magnetic fluid spiral groove of the rotor and the magnetic conductive ring pole shoe, the magnetic fluid spiral groove is used for realizing the rotation shaft dynamic sealing of the magnetic fluid, the permanent magnet ring is used for providing an additional constant magnetic field for the magnetic fluid and providing a permanent magnetic bias magnetic path between the active control side stator and the radial magnetic bearing rotor laminated sheet, and the magnetic conductive ring pole shoe is used for serving as a control pole shoe of the magnetic fluid and closing the permanent magnetic bias magnetic path of the hybrid magnetic bearing. The technical scheme of the application is applied to solve the technical problem of the excessive length of the axial length of the magnetic fluid sealed magnetic bearing in the prior art.

Description

Technical Field

[0001] This invention relates to the field of magnetohydrodynamic sealing technology, and more particularly to a hybrid magnetic bearing with magnetohydrodynamic sealing. Background Technology

[0002] Magnetofluid, also known as magnetic liquid or ferrofluid, possesses both the magnetism of solid magnetic materials and the fluidity of liquids. It is a solid-liquid two-phase colloidal material composed of nanoscale magnetic solid particles, a carrier liquid, and surfactants. This fluid only exhibits magnetism when an external magnetic field is applied. It has good fluidity, lubricity, and sealing properties. With the application of a suitable magnetic field, the magnetofluid can fill annular spaces, establishing a series of "O-rings" to achieve a sealing effect.

[0003] Hybrid magnetic bearings, also known as permanent magnet biased magnetic bearings, are simply called hybrid magnetic bearings. The coil windings of hybrid magnetic bearings only supply control current and do not require bias current. Therefore, compared to electromagnetic bearings, they have advantages such as lower power consumption, less heat generation, smaller size, shorter axial length, and fewer power amplifiers required. Figure 3 The permanent magnet biased radial two-degree-of-freedom magnetic bearing, represented by this type, has a relatively independent permanent magnet circuit, and the permanent magnet guide ring only serves to close the permanent magnet circuit.

[0004] Currently, magnetic bearing machinery mainly uses magnetohydrodynamic seals in a split arrangement or parallel layout, which occupies a long axial length and is not conducive to improving the rotor's limiting speed. Summary of the Invention

[0005] This invention provides a hybrid magnetic bearing with a magnetohydrodynamic seal, which can solve the technical problem of excessive axial length in existing magnetohydrodynamic seal magnetic bearings.

[0006] According to one aspect of the present invention, a hybrid magnetic bearing with magnetohydrodynamic sealing is provided. The hybrid magnetic bearing with magnetohydrodynamic sealing includes: a base; a magnetic bearing assembly, the magnetic bearing assembly including an active control side stator, a permanent magnet ring, a magnetically conductive ring pole shoe, a control coil, radial magnetic bearing rotor laminations, and a rotor. The radial magnetic bearing rotor laminations are sleeved on the rotor. The active control side stator is fixedly disposed within the base. The radial magnetic bearing rotor laminations are disposed within the active control side stator and coaxially disposed with the active control side stator. The control coil is wound around the magnetic poles of the active control side stator. The control coil is used to apply current to the rotor when it is not in an equilibrium position to generate a magnetic force to pull the rotor back to the equilibrium position. The permanent magnet ring and the magnetically conductive ring pole shoe are both disposed within 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 magnetically conductive ring pole shoe. The rotor end has a magnetohydrodynamic helical groove. A magnetofluid is disposed between the shoes. The magnetofluid helical groove is used to achieve dynamic sealing of the magnetofluid shaft. The magnetic guide ring pole shoe and the permanent magnet ring are both coaxially arranged with the rotor. The permanent magnet ring is used to provide an external constant magnetic field to the magnetofluid and to provide permanent magnet bias flux between the stator on the active control side and the radial magnetic bearing rotor lamination. The magnetic guide ring pole shoe is used to act as the control pole shoe of the magnetofluid and to close the permanent magnet bias magnetic circuit of the hybrid magnetic bearing. 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 disposed in the base and is coaxially arranged with the rotor. The displacement sensor stator and the sensor rotor lamination work together to output the radial displacement signal of the rotor. The protective bearing assembly is disposed on the base. The rotor is rotatably disposed on the protective bearing assembly. The protective bearing assembly is used to provide temporary support for the rotor when the magnetic bearing assembly starts and stops and when it fails.

[0007] Furthermore, the base includes a magnetic bearing housing and a housing, the magnetic bearing housing is fixedly connected to the housing, the magnetic bearing assembly is disposed inside the magnetic bearing housing, the displacement sensor stator is fixedly connected to the magnetic bearing housing, and the protective bearing assembly is fixedly connected to the housing.

[0008] Furthermore, the protective bearing assembly includes a protective bearing and a protective bearing housing. The protective bearing housing is fixedly connected to the housing, the protective bearing is disposed within the protective bearing housing, and the rotor is rotatably disposed within 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, both the stator on the active control side and the rotor laminations of the radial magnetic bearing are made of silicon steel sheets.

[0011] Furthermore, the permanent magnet ring is made of neodymium iron boron material through sintering.

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

[0013] This invention provides a hybrid magnetic bearing with a magnetohydrodynamic (MHD) seal. The hybrid magnetic bearing uses a magnetic guide ring pole shoe as the guide ring, and the rotor end has a magnetohydrodynamic (MHD) helical groove. When the rotor rotates, it drives the magnetohydrodynamic fluid towards the vacuum direction. The helical seal used in this hybrid magnetic bearing is a non-contact dynamic seal device for the shaft, employing reverse fluid dynamic pressure transmission. When the shaft rotates, the helical groove on the rotor surface pumps the magnetohydrodynamic fluid within the narrow gap, converting the rotational kinetic energy of the helical groove into the pressure energy of the magnetohydrodynamic fluid, thereby improving the sealing vacuum and shortening the axial length of the MHD seal structure. Compared to the conventional method of using only a helical seal, which results in poor sealing at low shaft speeds, this invention combines a magnetohydrodynamic seal with a helical seal. This solves both the failure problem of the magnetohydrodynamic seal at high speeds and the leakage problem of the helical seal during shutdown and low speeds, achieving a more stable sealing effect at different speeds. Through appropriate dimensional settings, it can achieve good sealing while having almost no impact on the control of the hybrid magnetic bearing, thus solving the problem of excessive axial length in magnetohydrodynamic sealed magnetic bearings. Therefore, compared with the prior art, the hybrid magnetic bearing with magnetic fluid sealing provided by this invention cleverly uses the permanent magnet circuit poles of the hybrid magnetic bearing as magnetic fluid pole shoes. Through appropriate size settings, 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 rotor surface. The spiral groove acts as a pump for the liquid in the narrow gap formed between the shaft and the stator, converting the rotational kinetic energy of the spiral groove into the pressure energy of the liquid, thereby preventing the leakage of the sealed liquid and effectively solving the problem of excessive axial length of the magnetic bearing with magnetic fluid sealing. Attached Figure Description

[0014] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0015] Figure 1 A schematic diagram of the overall structure of a hybrid magnetic bearing with a magnetohydrodynamic seal provided according to a specific embodiment of the present invention is shown;

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

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

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

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

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

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

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0025] like Figures 1 to 5As shown, a specific embodiment of the present invention provides a hybrid magnetic bearing with a magnetohydrodynamic seal. This hybrid magnetic bearing includes a base 10, a magnetic bearing assembly 20, a displacement sensor 30, and a protective bearing assembly 40. The magnetic bearing assembly 20 includes an active control side stator 21, a permanent magnet ring 22, a magnetic guide ring pole shoe 23, a control coil 24, radial magnetic bearing rotor laminations 25, and a rotor 26. The radial magnetic bearing rotor laminations 25 are sleeved on the rotor 26. The active control side stator 21 is fixedly disposed within the base 10. The radial magnetic bearing rotor... Laminated laminations 25 are disposed within and coaxially with the active control side stator 21. Control coils 24 are wound around the magnetic poles of the active control side stator 21. The control coils 24 are used to apply current to the rotor 26 when it is not in a balanced position, generating magnetic force to pull the rotor back to the balanced position. Permanent magnet rings 22 and magnetically conductive pole shoes 23 are both disposed within 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 is in contact with the magnetically conductive pole shoe 23. The ends of the rotor 26 have magnetohydrodynamic spiral grooves. 26a, a magnetic fluid is provided between the magnetic fluid helical groove 26a and the magnetic ring pole shoe 23 of the rotor. The magnetic fluid helical groove 26a is used to achieve a dynamic seal of the magnetic fluid shaft. 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 to provide permanent magnet bias flux between the stator 21 on the active control side and the radial magnetic bearing rotor lamination 25. The magnetic ring pole shoe 23 is used to act as the control pole shoe of the magnetic fluid and to close the permanent magnet bias magnetic circuit of the hybrid magnetic bearing; displacement sensor 30 The system 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 disposed within the base 10 and coaxially arranged with the rotor 26. The displacement sensor stator 31 and the sensor rotor lamination 32 work together to output a radial displacement signal of the rotor. A protective bearing assembly 40 is disposed on the base 10. The rotor 26 is rotatably disposed on the protective bearing assembly 40. The protective bearing assembly 40 is used to provide temporary support for the rotor 26 during the start-up and shutdown of the magnetic bearing assembly 20 and in the event of failure.

[0026] This configuration provides a hybrid magnetic bearing with a magnetohydrodynamic (MHD) seal. The hybrid magnetic bearing uses a magnetic guide ring pole shoe as the guide ring, and the rotor end has a magnetohydrodynamic (MHD) helical groove. When the rotor rotates, it drives the magnetohydrodynamic fluid towards the vacuum direction. The helical seal used in this hybrid magnetic bearing is a non-contact dynamic seal device for the shaft, employing reverse hydrodynamic pressure transmission. When the shaft rotates, the helical groove on the rotor surface pumps the magnetohydrodynamic fluid within the narrow gap, converting the rotational kinetic energy of the helical groove into the pressure energy of the magnetohydrodynamic fluid, thereby improving the sealing vacuum and shortening the axial length of the MHD seal structure. Compared to the conventional method of using only a helical seal, which has poor sealing performance at low shaft speeds, this invention combines a magnetohydrodynamic seal with a helical seal. This solves both the failure problem of the magnetohydrodynamic seal at high speeds and the leakage problem of the helical seal during shutdown and low speeds, achieving a more stable sealing effect at different speeds. Through appropriate dimensional settings, it can achieve good sealing performance with minimal impact on the hybrid magnetic bearing control, thus solving the problem of excessive axial length in magnetohydrodynamic (MHD) sealed magnetic bearings. Therefore, compared with the prior art, the hybrid magnetic bearing with magnetic fluid sealing provided by this invention cleverly uses the permanent magnet circuit poles of the hybrid magnetic bearing as magnetic fluid pole shoes. Through appropriate size settings, 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 rotor surface. The spiral groove acts as a pump for the liquid in the narrow gap formed between the shaft and the stator, converting the rotational kinetic energy of the spiral groove into the pressure energy of the liquid, thereby preventing the leakage of the sealed liquid and effectively solving the problem of excessive axial length of the magnetic bearing with magnetic fluid sealing.

[0027] Furthermore, in this invention, in order to facilitate the installation of the magnetic bearing assembly, the displacement sensor, and the protective bearing assembly, as well as 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 disposed inside 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] Furthermore, in this invention, in order to provide temporary support for the rotor 26 during the start-up and shutdown of the hybrid magnetic bearing and in the event of failure, the protective bearing assembly 40 can be configured to include a protective bearing 41 and a protective bearing housing 42. The protective bearing housing 42 is fixedly connected to the housing 12, the protective bearing 41 is disposed in the protective bearing housing 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] Furthermore, in this invention, to reduce eddy current losses, both the active control side stator 21 and the radial magnetic bearing rotor laminations 25 are made of laminated silicon steel sheets. Silicon steel sheets have extremely low carbon content and a silicon content as high as 0.5%-4.5%. Silicon gives them excellent electromagnetic properties, specifically low core loss, high permeability, low coercivity, and low magnetic aging. They also have good machinability, with a high stacking coefficient and good stamping properties. As a specific embodiment of this invention, both the active control side stator 21 and the radial magnetic bearing rotor laminations 25 use 0.35mm silicon steel sheets. Their magnetic induction intensity is linear below 1.4T, and the saturation magnetic induction intensity is 1.7T. This is only a preferred embodiment; other ferromagnetic materials can also be used for the active control side stator 21 and the radial magnetic bearing rotor laminations 25 depending on the actual application. As another embodiment of this invention, if the load is relatively constant and the control current hardly changes during actual use, the active control side stator 21 can also be made of a single piece of high-permeability material, and the radial magnetic bearing rotor laminations can be omitted.

[0031] Furthermore, in this invention, the permanent magnet ring 22 is sintered from neodymium iron boron permanent magnet material (an existing material). It is a tetragonal crystal formed from neodymium, iron, and boron, possessing a high magnetic energy product and excellent magnetic properties, and is widely used in electrical machinery, electronics, and other fields. This structure uses N35EH permanent magnet material, with a maximum magnetic energy product of 287 kJ / m². 3 The maximum operating temperature is 200℃. If the annular area is large and the magnetization is uneven, it can also be assembled from small pieces of permanent magnets. This is only a preferred embodiment; the permanent magnet ring 22 can also be made of other permanent magnet materials depending on the actual application.

[0032] Furthermore, in this invention, to ensure the magnetic permeability of the magnetic ring pole shoe 23, the material of the magnetic ring pole shoe 23 includes electrical pure iron. 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. It has good electromagnetic properties, specifically high saturation magnetic induction, low coercivity, high permeability, stable magnetism without magnetic aging, and is inexpensive with good hot and cold working properties, making it widely used in related components with electromagnet structures. As a specific embodiment of this invention, this structure uses electrical pure iron of type DT4C, whose linear region is below 1.5T, and whose saturation magnetic induction is 1.8T. This is only a preferred embodiment; other ferromagnetic materials can also be used for the magnetic ring pole shoe 23 depending on the actual application.

[0033] To gain a further understanding of the present invention, the following description is provided in conjunction with... Figures 1 to 5 The present invention provides a detailed description of the hybrid magnetic bearing with a magnetohydrodynamic seal.

[0034] like Figures 1 to 5As shown, a specific embodiment of the present invention provides a hybrid magnetic bearing with a magnetohydrodynamic seal. This hybrid magnetic bearing includes a base 10, a magnetic bearing assembly 20, a displacement sensor 30, and a protective bearing assembly 40. The magnetic bearing assembly 20 includes an active control side stator 21, a permanent magnet ring 22, a magnetic guide ring pole shoe 23, a control coil 24, radial magnetic bearing rotor laminations 25, and a rotor 26. The radial magnetic bearing rotor laminations 25 are sleeved on the rotor 26. The active control side stator 21 is fixedly disposed within the base 10. The radial magnetic bearing rotor... Laminated laminations 25 are disposed within and coaxially with the active control side stator 21. Control coils 24 are wound around the magnetic poles of the active control side stator 21. The control coils 24 are used to apply current to the rotor 26 when it is not in a balanced position, generating magnetic force to pull the rotor back to the balanced position. Permanent magnet rings 22 and magnetically conductive pole shoes 23 are both disposed within 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 is in contact with the magnetically conductive pole shoe 23. The ends of the rotor 26 have magnetohydrodynamic spiral grooves. 26a, a magnetic fluid is provided between the magnetic fluid helical groove 26a and the magnetic ring pole shoe 23 of the rotor. The magnetic fluid helical groove 26a is used to achieve a dynamic seal of the magnetic fluid shaft. 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 to provide permanent magnet bias flux between the stator 21 on the active control side and the radial magnetic bearing rotor lamination 25. The magnetic ring pole shoe 23 is used to act as the control pole shoe of the magnetic fluid and to close the permanent magnet bias magnetic circuit of the hybrid magnetic bearing; displacement sensor 30 The system 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 disposed within the base 10 and coaxially arranged with the rotor 26. The displacement sensor stator 31 and the sensor rotor lamination 32 work together to output a radial displacement signal of the rotor. A protective bearing assembly 40 is disposed on the base 10, and the rotor 26 is rotatably disposed on the protective bearing assembly 40. The protective bearing assembly 40 is used to provide temporary support for the rotor 26 during the start-up and shutdown of the magnetic bearing assembly 20 and in case of failure. The base 10 includes a magnetic bearing housing 11 and a housing 12. The magnetic bearing housing 11 is fixedly connected to the housing 12. The magnetic bearing assembly 20 is disposed within the magnetic bearing housing 11. The displacement sensor stator 31 is fixedly connected to the magnetic bearing housing 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 housing 42. The protective bearing housing 42 is fixedly connected to the housing 12. The protective bearing 41 is disposed inside the protective bearing housing 42. The rotor 26 is rotatably disposed inside the protective bearing 41.

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

[0036] In this embodiment, the active control side stator 21 has an 8-pole structure, with each pole wound with a coil of a designed number of turns. The coils in the same direction are connected in series with the magnetic bearing controller, for example... Figure 4a The four magnetic poles marked with their polarities 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 magnetic poles have opposite polarities. Figure 4a The four magnetic poles, whose polarity is not explicitly 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. The silicon steel sheets have extremely low carbon content and high silicon content (0.5%-4.5%). Silicon gives them excellent electromagnetic properties, specifically low core loss, high permeability, low coercivity, and low magnetic aging. They also have good machinability, with a high stacking factor and good stamping properties. This structure uses 0.35mm silicon steel sheets, with a linear magnetic flux density below 1.4T and a saturation magnetic flux density of 1.7T.

[0037] The permanent magnet ring is axially magnetized and sintered from neodymium iron boron (NdFeB) material. NdFeB is a tetragonal crystal composed of neodymium, iron, and boron, possessing high magnetic energy product and excellent magnetic properties, and is widely used in electrical machinery, electronics, and other fields. This structure uses N35EH permanent magnet material, with a maximum magnetic energy product of 287 kJ / m². 3 The maximum operating temperature is 200℃. If the annular area is large and the magnetization is uneven, it can also be assembled from small pieces of permanent magnets.

[0038] The magnetic ring pole shoe 23 serves to close the permanent magnet circuit in the magnetic bearing assembly and acts as a magnetic shoe in the magnetohydrodynamic sealing structure. It is made of electrical pure iron with good magnetic permeability. 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. It has good electromagnetic properties, specifically high saturation magnetic induction, low coercivity, high permeability, magnetic stability without magnetic aging, and low price. It also has good cold and hot working properties and is widely used in related components with electromagnet structures. This structure uses electrical pure iron of type DT4C, whose linear region is below 1.5T and whose saturation magnetic induction is 1.8T.

[0039] In this embodiment, the active control side stator 21 has 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, or 12-pole structure, with a similar principle. The material is not limited to silicon steel sheets. If the load is relatively constant and the control current hardly changes in actual use, a large block of high-permeability material can be selected.

[0040] Hybrid magnetic bearing magnetic circuit, such as Figure 2 and Figure 3As shown, the solid line represents the permanent magnet bias flux generated by the permanent magnet, and the dotted line represents the control flux generated by the control coil. Its working principle is as follows: At the equilibrium position, the bias flux generated by the permanent magnet is the same in all air gaps, the control flux is 0, and the net force on the rotor is 0. When the rotor undergoes radial displacement (taking the y+ direction as an example), the upper air gap decreases, the lower air gap increases, and the control coil applies current. This weakens the superposition of the permanent magnet flux and control flux in the upper air gap, while strengthening the superposition of the permanent magnet flux and control flux in the lower air gap, generating a downward net force on the rotor that pulls it back to the equilibrium position.

[0041] Magnetohydrodynamic seals, such as Figure 5 As shown, the pole shoe is a hybrid magnetic bearing guide ring, and the rotor uses a screw structure, which can drive the magnetofluid to be transported towards the vacuum direction when the rotor rotates. The spiral seal used in this structure is a non-contact rotating shaft dynamic seal device, which adopts reverse transmission of fluid dynamic pressure. When the shaft rotates, the spiral grooves on the rotor surface pump the magnetofluid in the narrow gap, converting the rotational kinetic energy of the spiral grooves into the pressure energy of the magnetofluid, thereby improving the sealing vacuum degree and shortening the axial length occupied by the magnetofluid seal structure.

[0042] In summary, this invention provides a hybrid magnetic bearing with a magnetohydrodynamic seal. Compared with existing technologies, this hybrid magnetic bearing cleverly uses the permanent magnet circuit poles of the hybrid magnetic bearing as magnetohydrodynamic pole shoes. Through appropriate dimensional settings, it can achieve good sealing effect while having almost no impact on the control of the hybrid magnetic bearing. At the same time, a helical groove is opened on the rotor surface. The helical groove acts as a pump for the liquid in the narrow gap formed between the shaft and the stator, converting the rotational kinetic energy of the helical groove into the pressure energy of the liquid, thereby preventing leakage of the sealed liquid and effectively solving the problem of excessive axial length of the magnetohydrodynamic seal magnetic bearing.

[0043] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0044] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0045] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hybrid magnetic bearing with a magnetohydrodynamic seal, characterized in that, The magnetohydrodynamic sealed hybrid magnetic bearing includes: Base (10); A 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 disposed within the base (10). The radial magnetic bearing rotor lamination (25) is disposed within the active control side stator (21) and coaxially disposed with the active control side stator (21). The control coil (24) is wound around the magnetic poles of the active control side stator (21). The control coil (24) is used to apply current to the rotor (26) when it is not in a balanced position to generate magnetic force to pull the rotor back to the balanced position. The permanent magnet ring (22) and the magnetic ring pole shoe (23) are both disposed within the base (10). Inside 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 guide ring pole shoe (23). The end of the rotor (26) has a magnetic fluid spiral groove (26a). A magnetic fluid is provided between the magnetic fluid spiral groove (26a) of the rotor and the magnetic guide ring pole shoe (23). The magnetic fluid spiral groove (26a) is used to realize the dynamic sealing of the magnetic fluid shaft. The magnetic guide 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 to provide permanent magnet bias flux between the active control side stator (21) and the radial magnetic bearing rotor lamination (25). The magnetic guide ring pole shoe (23) is used to act as the control pole shoe of the magnetic fluid and to close the permanent magnet bias magnetic circuit of the hybrid magnetic bearing. The displacement sensor (30) 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 disposed in the base (10) and coaxially disposed with the rotor (26). The displacement sensor stator (31) and the sensor rotor lamination (32) work together to output a rotor radial displacement signal. A protective bearing assembly (40) is disposed on the base (10), and the rotor (26) is rotatably disposed on the protective bearing assembly (40). The protective bearing assembly (40) is used to provide temporary support for the rotor (26) during the start-up and shutdown of the magnetic bearing assembly (20) and in case of failure. The active control side stator (21) and the radial magnetic bearing rotor laminations (25) are both made of silicon steel sheets, and the silicon content of the silicon steel sheets is 0.5%-4.5%.

2. The hybrid magnetic bearing with a magnetohydrodynamic seal according to claim 1, characterized in that, The base (10) includes 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 disposed in the magnetic bearing seat (11). The displacement sensor stator (31) is fixedly connected to the magnetic bearing seat (11). The protective bearing assembly (40) is fixedly connected to the housing (12).

3. The hybrid magnetic bearing with a magnetohydrodynamic seal according to claim 2, characterized in that, The protective bearing assembly (40) includes a protective bearing (41) and a protective bearing housing (42). The protective bearing housing (42) is fixedly connected to the housing (12). The protective bearing (41) is disposed in the protective bearing housing (42). The rotor (26) is rotatably disposed in the protective bearing (41).

4. The hybrid magnetic bearing with a magnetohydrodynamic seal according to any one of claims 1 to 3, characterized in that, 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.

5. The hybrid magnetic bearing with a magnetohydrodynamic seal according to claim 1, characterized in that, The permanent magnet ring (22) is sintered from neodymium iron boron material.

6. The hybrid magnetic bearing with a magnetohydrodynamic seal according to claim 5, characterized in that, The material of the magnetic ring pole shoe (23) includes electrical pure iron.

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