Magnetic medium sealing device suitable for hollow rotating shaft

Abstract

The magnetic medium sealing device suitable for the hollow rotating shaft comprises a shell, the hollow rotating shaft and a magnetic sealing assembly, the hollow rotating shaft is arranged in the shell in a penetrating mode, a first permanent magnet surrounds the periphery of the hollow rotating shaft, and a first gap is reserved between the first permanent magnet and the hollow rotating shaft; the second permanent magnet is located on the side, facing the shell, of the hollow rotating shaft, a second gap is reserved between the second permanent magnet and the end of the hollow rotating shaft, the third permanent magnet surrounds the inner circumference of the hollow rotating shaft, a third gap is reserved between the third permanent magnet and the hollow rotating shaft, and the outer circumferential face of the hollow rotating shaft is provided with first pole teeth protruding towards the first gap. The end face of the hollow rotating shaft is provided with second pole teeth protruding towards the second gap, and the peripheral face of the third permanent magnet is provided with third pole teeth protruding towards the third gap. According to the magnetic medium sealing device suitable for the hollow rotating shaft, three-stage sealing is formed on the inner side, the outer side and the end of the hollow rotating shaft, and the requirements for sealing reliability and equipment light weight are met.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic sealing, and in particular to a magnetic medium sealing device suitable for a hollow rotating shaft. Background Art

[0002] Magnetic media sealing technology uses a gradient magnetic field to create a binding effect on magnetic media to achieve zero-leakage sealing, and has important application prospects in the aerospace field. Due to the dynamic deformation characteristics of hollow shafts during high-speed rotation—the centrifugal effect causes the hollow shaft to expand and elongate radially—traditional magnetic media sealing structures face significant technical bottlenecks in this special operating condition: the sealing gap design has an inherent contradiction. That is, while a smaller gap can ensure the pressure resistance of the magnetic media seal at low speeds, the mechanical interference between the shaft and the pole piece under high-speed conditions will cause the seal to fail. Increasing the gap can avoid the risk of interference, but it will lead to a decrease in pressure resistance. If the sealing capacity is compensated by increasing the number of pole pieces, the weight of the magnetic media seal will increase significantly. Therefore, lightweight magnetic media seals suitable for hollow shafts have become a technical problem that needs to be solved urgently. Summary of the Invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, embodiments of the present invention propose a magnetic medium sealing device suitable for a hollow rotating shaft. This magnetic medium sealing device forms a three-level seal on the inside, outside, and end of the hollow rotating shaft, significantly improving sealing effectiveness. Compared to traditional solutions that rely on increasing the number of pole pieces on the outer circumference of the rotating shaft, this device balances sealing reliability with lightweight equipment, making it particularly suitable for aerospace vehicles, where weight and volume are critical.

[0005] The magnetic medium sealing device suitable for a hollow rotating shaft of an embodiment of the present invention includes: a shell, the shell having a accommodating cavity; a hollow rotating shaft and a magnetic sealing assembly, the hollow rotating shaft is arranged in the accommodating cavity along the axial direction of the shell, the magnetic sealing assembly includes a first permanent magnet, a second permanent magnet and a third permanent magnet, the first permanent magnet surrounds the outer circumference of the hollow rotating shaft and is sealed with the inner circumferential surface of the shell, and a first gap is reserved between the inner circumferential surface of the first permanent magnet and the outer circumferential surface of the hollow rotating shaft, the second permanent magnet is located on the side of the hollow rotating shaft facing the shell in the axial direction of the hollow rotating shaft and is sealed with the shell, and the second permanent magnet is annular extending along the circumferential direction of the hollow rotating shaft, a second gap is reserved between the second permanent magnet and the end of the hollow rotating shaft, and the third A permanent magnet surrounds the inner circumference of the hollow shaft and is sealed with the shell. A third gap is reserved between the third permanent magnet and the inner circumference of the hollow shaft, and the outer circumference of the hollow shaft has a plurality of first pole teeth protruding toward the first gap and arranged at intervals along the axial direction of the hollow shaft. The end face of the hollow shaft has a plurality of second pole teeth protruding toward the second gap and arranged at intervals along the radial direction of the end face of the hollow shaft. The outer circumference of the third permanent magnet has a plurality of third pole teeth protruding toward the third gap and arranged at intervals along the axial direction of the third permanent magnet. A first-level sealing layer is formed between the first pole teeth and the first permanent magnet, a second-level sealing layer is formed between the second pole teeth and the second permanent magnet, and a third-level sealing layer is formed between the third pole teeth and the inner circumference of the hollow shaft.

[0006] The embodiment of the present invention is a magnetic medium sealing device suitable for a hollow rotating shaft. The outer periphery of the hollow rotating shaft is provided with an annular first permanent magnet, the inner periphery is provided with an annular third permanent magnet, and the end is provided with an annular second permanent magnet. The outer peripheral surface of the hollow rotating shaft has a first pole tooth protruding toward the first permanent magnet to form a first-level seal, the end of the hollow rotating shaft has a second pole tooth protruding toward the second permanent magnet to form a second-level seal, and the outer peripheral surface of the third permanent magnet has a third pole tooth protruding toward the hollow rotating shaft to form a third-level seal. The sealing device of the present application forms a three-level seal on the inner side, outer side and end of the hollow rotating shaft, which greatly improves the sealing effect. Compared with the traditional technical solution that relies on increasing the number of pole shoes on the outer periphery of the rotating shaft, the present application takes into account the requirements of sealing reliability and lightweight equipment, and is particularly suitable for aerospace vehicles that are sensitive to weight and volume.

[0007] In some embodiments, the shell further includes an inner cylinder, which is connected to the bottom wall of the shell and protrudes toward the interior of the hollow rotating shaft, and the third permanent magnet surrounds the outer circumference of the inner cylinder and is sealed with the outer circumferential surface of the inner cylinder.

[0008] In some embodiments, a first retaining spring and a first magnetic isolation ring are provided on the outer peripheral surface of the inner cylinder and are arranged around its circumference. The first magnetic isolation ring is located on the side of the third permanent magnet facing the bottom wall and is clamped between the third permanent magnet and the bottom wall. The first retaining spring is clamped on the side of the third permanent magnet facing away from the first magnetic isolation ring.

[0009] In some embodiments, a second retaining spring and a second magnetic isolation ring are provided on the inner circumferential surface of the shell and are arranged around the shell in a circumferential direction. The second magnetic isolation ring is located on the side of the first permanent magnet facing the bottom wall and is clamped between the first permanent magnet and the bottom wall. The second retaining spring is clamped on the side of the first permanent magnet facing away from the second magnetic isolation ring.

[0010] In some embodiments, an assembly groove is provided on the bottom wall, and the second permanent magnet is clamped in the assembly groove.

[0011] In some embodiments, a first sealing ring is provided between the first permanent magnet and the inner circumference of the shell; and / or, a second sealing ring is provided between the second permanent magnet and the bottom wall; and / or, a third sealing ring is provided between the third permanent magnet and the outer circumference of the inner cylinder.

[0012] In some embodiments, the outer circumference and inner circumference of the hollow rotating shaft are respectively covered with an outer magnetic sleeve and an inner magnetic sleeve, the outer circumference of the outer magnetic sleeve is provided with the first pole teeth, the ends of the outer magnetic sleeve and the inner magnetic sleeve facing the bottom wall are both provided with the second pole teeth, and a fourth sealing ring is provided between the outer magnetic sleeve and the hollow rotating shaft, and a fifth sealing ring is provided between the inner magnetic sleeve and the hollow rotating shaft.

[0013] In some embodiments, the outer circumferential surface of the hollow shaft is further provided with a third clamping spring arranged along its circumference, and the third clamping spring is clamped on a side of the outer magnetic conductive sleeve away from the second permanent magnet;

[0014] And / or, the inner circumferential surface of the hollow rotating shaft is further provided with a fourth clamping spring arranged along the circumference thereof, and the fourth clamping spring is clamped on the side of the inner magnetic conductive sleeve away from the second permanent magnet.

[0015] In some embodiments, the value of the first gap is determined based on the radial elongation caused by the centrifugal force caused by the rated speed of the hollow shaft, the value of the second gap is determined based on processing and assembly errors, and the value of the third gap is determined based on the optimal gap value of traditional magnetic medium sealing.

[0016] In some embodiments, a first groove is provided on the outer circumference of the hollow shaft, the first pole tooth is arranged on the bottom wall of the first groove, a second groove is provided at the end of the hollow shaft, and the second pole tooth is arranged on the bottom wall of the second groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 3 is a schematic structural diagram of a magnetic medium sealing device suitable for a hollow shaft according to an embodiment of the present invention.

[0018] Figure 2 yes Figure 1 A magnified view of the local structure.

[0019] Figure 3 This is a structural diagram of a magnetic medium sealing device suitable for a hollow shaft according to another embodiment of the present invention.

[0020] Figure 4 yes Figure 3 A magnified view of the local structure.

[0021] Reference numerals:

[0022] Hollow shaft 1, sixth sealing ring 2, second retaining spring 3, first sealing ring 4, first permanent magnet 5, shell 6, second magnetic isolation ring 7, second permanent magnet 8, second sealing ring 9, first magnetic isolation ring 10, third permanent magnet 11, first retaining spring 12, third sealing ring 13, third retaining spring 14, outer magnetic conductive sleeve 15, fourth sealing ring 16, fourth retaining spring 17, inner magnetic conductive sleeve 18, fifth sealing ring 19, bottom wall 20, inner cylinder 21. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0024] like Figure 1-Figure 4 As shown, the magnetic medium sealing device applicable to the hollow rotating shaft according to the embodiment of the present invention includes a housing 6, a hollow rotating shaft 1 and a magnetic sealing assembly.

[0025] Specifically, if Figure 1 and Figure 2As shown, the shell 6 has a accommodating cavity, and the hollow shaft 1 is arranged in the accommodating cavity along the axial direction of the shell 6. The magnetic sealing assembly includes a first permanent magnet 5, a second permanent magnet 8 and a third permanent magnet 11. The first permanent magnet 5 surrounds the outer circumference of the hollow shaft 1 and is sealed with the inner circumference of the shell 6, and a first gap is reserved between the inner circumference of the first permanent magnet 5 and the outer circumference of the hollow shaft 1. The second permanent magnet 8 is located on the side of the hollow shaft 1 facing the shell 6 in the axial direction of the hollow shaft 1 and is sealed with the shell 6. The second permanent magnet 8 is annular and extends along the circumference of the hollow shaft 1. A second gap is reserved between the second permanent magnet 8 and the end of the hollow shaft 1. The third permanent magnet 11 surrounds the inner circumference of the hollow shaft 1 and is sealed with the shell 6. The third permanent magnet A third gap is reserved between 11 and the inner circumference of the hollow shaft 1, and the outer circumference of the hollow shaft 1 has a plurality of first pole teeth protruding toward the first gap and arranged at intervals along the axial direction of the hollow shaft 1, the end face of the hollow shaft 1 has a plurality of second pole teeth protruding toward the second gap and arranged at intervals along the radial direction of the end face of the hollow shaft 1, the outer circumference of the third permanent magnet 11 has a plurality of third pole teeth protruding toward the third gap and arranged at intervals along the axial direction of the third permanent magnet 11, a sufficient amount of magnetic medium is injected between the first pole tooth and the first permanent magnet 5 to form a first-level sealing layer, a sufficient amount of magnetic medium is injected between the second pole tooth and the second permanent magnet 8 to form a second-level sealing layer, and a sufficient amount of magnetic medium is injected between the third pole tooth and the inner circumference of the hollow shaft 1 to form a third-level sealing layer.

[0026] like Figure 1 As shown, the magnetic pole direction of the first permanent magnet 5 is the N pole on the inner circumference and the S pole on the outer circumference, the magnetic pole direction of the second permanent magnet 8 is the S pole on the end face close to the hollow shaft 1 and the N pole on the end face close to the shell 6, and the magnetic pole direction of the third permanent magnet 11 is the S pole on the inner circumference and the N pole on the outer circumference.

[0027] Alternatively, the magnetic pole direction of the first permanent magnet 5 is the S pole on the inner circumference and the N pole on the outer circumference, the magnetic pole direction of the second permanent magnet 8 is the N pole on the end face close to the hollow shaft 1 and the S pole on the end face close to the outer shell 6, and the magnetic pole direction of the third permanent magnet 11 is the N pole on the inner circumference and the S pole on the outer circumference.

[0028] It should be noted that, in the above embodiment, the hollow shaft 1 and the housing 6 are made of materials with good magnetic conductivity, and the permanent magnet is made of permanent magnetic material with good magnetic properties. Figure 1 As shown, the magnetic lines of force starting from the N pole of the first permanent magnet 5 reach the S pole of the second permanent magnet 8 via the hollow shaft 1, and the magnetic lines of force starting from the N pole of the second permanent magnet 8 return to the S pole of the permanent magnet I via the shell 6, so as to form a first closed magnetic circuit; a first gap is formed between the first permanent magnet 5 and the hollow shaft 1, that is, the first-level sealing layer; a second gap is formed between the hollow shaft 1 and the second permanent magnet 8, that is, the second-level sealing layer.

[0029] Pole teeth are provided on the outer peripheral surface of the third permanent magnet 11. The magnetic lines of force starting from the N pole of the third permanent magnet 11 reach the S pole of the second permanent magnet 8 via the hollow shaft 1. The magnetic lines of force starting from the N pole of the second permanent magnet 8 return to the third permanent magnet 11 via the shell 6 to form a second closed magnetic circuit; a third gap is formed between the hollow shaft 1 and the third permanent magnet 11, i.e., a third-level sealing layer.

[0030] Thus, a first-level seal can be formed between the hollow shaft 1 and the first permanent magnet 5 on the outside of the shaft, a second-level seal can be formed between the hollow shaft 1 and the second permanent magnet 8 at the end of the shaft, and a third-level seal can be formed between the hollow shaft 1 and the third permanent magnet 11 on the inner periphery of the shaft. When gas leaks, it must pass through the first, second and third-level seals in sequence, which greatly improves the reliability of the seal. In addition, the present application replaces the traditional technical solution of relying on adding pole shoes to the outer periphery of the shaft by designing multi-stage seals at three different positions, taking into account the requirements of sealing reliability and lightweight equipment.

[0031] The embodiment of the present invention is a magnetic medium sealing device suitable for a hollow rotating shaft. The outer periphery of the hollow rotating shaft 1 is provided with an annular first permanent magnet 5, the inner periphery is provided with an annular third permanent magnet 11, and the end is provided with an annular second permanent magnet 8. The outer peripheral surface of the hollow rotating shaft 1 has a first pole tooth protruding toward the first permanent magnet 5 to form a first-level sealing layer, the end of the hollow rotating shaft 1 has a second pole tooth protruding toward the second permanent magnet 8 to form a second-level sealing layer, and the inner peripheral surface of the third permanent magnet 11 has a third pole tooth protruding toward the hollow rotating shaft 1 to form a third-level sealing layer. The sealing device of the present application forms a three-level seal on the inner side, outer side and end of the hollow rotating shaft 1, which greatly improves the sealing effect. Compared with the traditional technical solution that relies on increasing the number of pole shoes on the outer periphery of the rotating shaft, the present application takes into account the requirements of sealing reliability and lightweight equipment, and is particularly suitable for aerospace vehicles that are sensitive to weight and volume.

[0032] It should be noted that the magnetic sealing medium of the present application includes but is not limited to magnetic media such as magnetic particles, magnetic liquid, magnetorheological fluid, and magnetic grease.

[0033] In addition, if Figure 1 and Figure 2 As shown, the lightweight magnetic medium sealing design of the present invention no longer has a magnetic pole shoe structure, but directly opens pole teeth on the permanent magnet, which can significantly reduce the size and weight of the sealing structure, and is particularly suitable for aerospace vehicles that are sensitive to weight and volume.

[0034] Furthermore, the first pole teeth of the present application are arranged on the outer peripheral surface of the hollow rotating shaft 1, and the first permanent magnet 5 is not provided with pole teeth to keep the inner peripheral surface flat, so as to avoid the magnetic sealing medium being thrown out between the teeth under high rotation, thereby further ensuring the sealing reliability.

[0035] Similarly, the second pole teeth are positioned on the end face of hollow shaft 1, with the inner surface of second permanent magnet 8 remaining flat. The third pole teeth are positioned on the outer circumference of third permanent magnet 11, with the inner circumference of hollow shaft 1 remaining flat. The resulting effect is similar to that of the first pole teeth, and will not be further elaborated here. Specifically, the positioning of pole teeth on the outer circumference of hollow shaft 1 and the outer circumference of third permanent magnet 11 effectively suppresses centrifugal force interference with the spatial distribution of the magnetic medium, ensuring stable retention of the magnetic medium within the pole tooth region even under high-speed operating conditions.

[0036] Further, if Figure 1 As shown, the housing 6 further includes an inner cylinder, which is connected to the bottom wall 20 of the housing 6 and protrudes toward the interior of the hollow shaft 1. The third permanent magnet 11 surrounds the outer circumference of the inner cylinder and is sealed to the outer circumferential surface of the inner cylinder. In other words, the inner cylinder can serve as a support member, providing an assembly support platform for the third permanent magnet 11.

[0037] Further, if Figure 1 As shown, the outer circumference of the inner cylinder is provided with a first retaining spring 12 and a first magnetic isolation ring 10, which are arranged along its circumference. The first magnetic isolation ring 10 is located on the side of the third permanent magnet 11 facing the bottom wall 20 and is sandwiched between the third permanent magnet 11 and the bottom wall 20. The first retaining spring 12 is retained on the side of the third permanent magnet 11 facing away from the first magnetic isolation ring 10. Thus, the first magnetic isolation ring 10 and the first retaining spring 12 achieve axial positioning of the third permanent magnet 11 during assembly. Specifically, the first magnetic isolation ring 10 is transitionally fitted with the inner cylinder, and the outer circumference of the inner cylinder is provided with a groove to accommodate the first retaining spring 12.

[0038] Further, if Figure 1 As shown, the inner circumferential surface of the housing 6 is provided with a second retaining spring 3 and a second magnetic isolation ring 7 arranged along its circumference. The second magnetic isolation ring 7 is located on the side of the first permanent magnet 5 facing the bottom wall 20 and is clamped between the first permanent magnet 5 and the bottom wall 20. The second retaining spring 3 is clamped on the side of the first permanent magnet 5 facing away from the second magnetic isolation ring 7. Thus, the second magnetic isolation ring 7 and the second retaining spring 3 can achieve the assembly and positioning of the first permanent magnet 5. Specifically, the second magnetic isolation ring 7 is transitionally fitted with the housing 6, and a retaining groove for accommodating the second retaining spring 3 is provided on the inner circumferential surface of the housing 6.

[0039] Further, if Figure 1 As shown, the bottom wall 20 is provided with an assembly groove, and the second permanent magnet 8 is clamped in the assembly groove. Therefore, the second permanent magnet 8 can be directly positioned by using the assembly groove to optimize the device structure.

[0040] Further, if Figure 1As shown, a first sealing ring 4 is provided between the first permanent magnet 5 and the inner circumference of the housing 6; and / or a second sealing ring 9 is provided between the second permanent magnet 8 and the bottom wall 20; and / or a third sealing ring 13 is provided between the third permanent magnet 11 and the outer circumference of the inner cylinder. Specifically, a groove for accommodating the first sealing ring 4 is provided on the outer circumference of the first permanent magnet 5. During assembly, the first sealing ring 4 can be assembled with the first permanent magnet 5 first and then assembled with the housing 6 as a whole. A groove for accommodating the third sealing ring 13 is provided on the inner circumference of the third permanent magnet 11. During assembly, the third sealing ring 13 is first assembled with the third permanent magnet 11 and then assembled with the inner cylinder as a whole. A groove for accommodating the second sealing ring 9 is provided on the outer side of the second permanent magnet 8. During assembly, the second sealing ring 9 is first assembled with the second permanent magnet 8 and then assembled with the housing 6 as a whole.

[0041] In addition, when the hollow shaft 1 is not suitable for setting pole teeth or the shaft is not magnetically conductive, a magnetic conductive sleeve can be added to the hollow shaft 1. Specifically, Figure 3 and Figure 4 As shown, the outer and inner circumferences of the hollow shaft 1 are respectively covered with an outer magnetic sleeve 15 and an inner magnetic sleeve 18. The outer circumference of the outer magnetic sleeve 15 is provided with a first pole tooth, and the ends of the outer magnetic sleeve 15 and the inner magnetic sleeve 18 facing the bottom wall 20 are both provided with a second pole tooth. A fourth sealing ring 16 is provided between the outer magnetic sleeve 15 and the hollow shaft 1, and a fifth sealing ring 19 is provided between the inner magnetic sleeve 18 and the hollow shaft 1. Specifically, a groove is provided on the outer circumference of the inner magnetic sleeve 18 to accommodate the fifth sealing ring 19. During assembly, the fifth sealing ring 19 is first assembled with the inner magnetic sleeve 18 and then assembled as a whole into the hollow shaft 1. The inner circumference of the outer magnetic sleeve 15 is provided with a groove to accommodate the fourth sealing ring 16. During assembly, the fourth sealing ring 16 is first assembled with the outer magnetic sleeve 15 and then assembled as a whole onto the outer side of the hollow shaft 1.

[0042] Furthermore, the outer circumferential surface of the hollow rotating shaft 1 is further provided with a third retaining spring 14 disposed along its circumference, and the third retaining spring 14 is retained on the side of the outer magnetic conductive sleeve 15 facing away from the second permanent magnet 8; and / or the inner circumferential surface of the hollow rotating shaft 1 is further provided with a fourth retaining spring 17 disposed along its circumference, and the fourth retaining spring 17 is retained on the side of the inner magnetic conductive sleeve 18 facing away from the second permanent magnet 8. In other words, the third retaining spring 14 and the fourth retaining spring 17 can respectively limit the assembly of the outer magnetic conductive sleeve 15 and the inner magnetic conductive sleeve 18.

[0043] It should be noted that, in the above embodiment, the retaining spring, the sealing ring and the magnetic isolation ring are all made of non-magnetic materials.

[0044] Furthermore, the value of the first gap is determined based on the radial elongation caused by the centrifugal force at the rated speed of hollow shaft 1. The value of the second gap is determined based on machining and assembly errors. The value of the third gap is determined based on the optimal gap value of traditional magnetic medium seals. As a result, under static and low-speed operating conditions, the larger first gap retains a preset safety distance to avoid the risk of interference caused by centrifugal elongation of the shaft. The third sealing layer maintains the minimum effective sealing gap value and cooperates with the second sealing layer to provide sufficient pressure resistance. When the speed increases, causing the shaft to elongate radially, the first gap dynamically contracts to form the main sealing interface, which cooperates with the second sealing layer to provide sufficient pressure resistance, achieving autonomous adaptation of sealing reliability across the entire operating range from static to high-speed conditions.

[0045] Specifically, the first sealing gap is c1, which satisfies 0.05 mm ≤ c1 - Gc ≤ 0.15 mm, where Gc is the centrifugal elongation.

[0046] The second sealing gap is c2, which satisfies 0.05mm≤c2≤0.15mm.

[0047] The third sealing gap is c3, which satisfies 0.05mm≤c3≤0.1mm.

[0048] In some embodiments, as Figure 3 As shown, a first groove is provided on the outer circumference of the hollow shaft 1, and the first pole teeth are arranged on the bottom wall of the first groove. A second groove is provided at the end of the hollow shaft 1, and the second pole teeth are arranged on the bottom wall of the second groove. As a result, the first pole teeth do not occupy additional radial space, and the second pole teeth do not occupy additional axial space, which facilitates the compactness of the device structure.

[0049] Furthermore, the housing 6 has a connection surface, on which a sixth sealing ring 2 is provided for sealing connection with an external device.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0052] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0053] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0054] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0055] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A magnetic medium sealing device suitable for a hollow shaft, characterized in that: include: a housing, wherein the housing has a receiving cavity; The cam is secured to the outer surface of the housing and is secured to a location adjacent to the housing when the cam is in the process of being moved. A third gap is reserved between the body and the inner circumference of the hollow shaft, and the outer circumference of the hollow shaft has a plurality of first pole teeth protruding toward the first gap and arranged at intervals along the axial direction of the hollow shaft, the end face of the hollow shaft has a plurality of second pole teeth protruding toward the second gap and arranged at intervals along the radial direction of the end face of the hollow shaft, the outer circumference of the third permanent magnet has a plurality of third pole teeth protruding toward the third gap and arranged at intervals along the axial direction of the third permanent magnet, a sufficient amount of magnetic medium is injected between the first pole teeth and the first permanent magnet to form a first-level sealing layer, a sufficient amount of magnetic medium is injected between the second pole teeth and the second permanent magnet to form a second-level sealing layer, and a sufficient amount of magnetic medium is injected between the third pole teeth and the inner circumference of the hollow shaft to form a third-level sealing layer.

2. The magnetic medium sealing device suitable for a hollow shaft according to claim 1, characterized in that: The shell further includes an inner cylinder connected to the bottom wall of the shell and protruding toward the interior of the hollow shaft. The third permanent magnet surrounds the outer circumference of the inner cylinder and is sealed with the outer circumferential surface of the inner cylinder.

3. The magnetic medium sealing device suitable for a hollow shaft according to claim 2, characterized in that: A first retaining spring and a first magnetic isolation ring are provided on the outer peripheral surface of the inner cylinder body and are arranged around the inner cylinder body in a circumferential direction. The first magnetic isolation ring is located on the side of the third permanent magnet facing the bottom wall and is clamped between the third permanent magnet and the bottom wall. The first retaining spring is clamped on the side of the third permanent magnet facing away from the first magnetic isolation ring.

4. The magnetic medium sealing device suitable for a hollow shaft according to claim 3, characterized in that: A second retaining spring and a second magnetic isolation ring are provided on the inner circumferential surface of the shell and are arranged around the shell in a circumferential direction. The second magnetic isolation ring is located on the side of the first permanent magnet facing the bottom wall and is clamped between the first permanent magnet and the bottom wall. The second retaining spring is clamped on the side of the first permanent magnet facing away from the second magnetic isolation ring.

5. The magnetic medium sealing device suitable for a hollow shaft according to claim 4, characterized in that: The bottom wall is provided with an assembly groove, and the second permanent magnet is clamped in the assembly groove.

6. The magnetic medium sealing device suitable for a hollow shaft according to claim 2, characterized in that: A first sealing ring is provided between the first permanent magnet and the inner circumference of the shell; and / or a second sealing ring is provided between the second permanent magnet and the bottom wall; and / or a third sealing ring is provided between the third permanent magnet and the outer circumference of the inner cylinder.

7. The magnetic medium sealing device suitable for a hollow shaft according to claim 4, characterized in that: The outer circumference and inner circumference of the hollow rotating shaft are respectively covered with an outer magnetic conductive sleeve and an inner magnetic conductive sleeve, the outer circumference of the outer magnetic conductive sleeve is provided with the first pole teeth, the ends of the outer magnetic conductive sleeve and the inner magnetic conductive sleeve facing the bottom wall are both provided with the second pole teeth, and a fourth sealing ring is provided between the outer magnetic conductive sleeve and the hollow rotating shaft, and a fifth sealing ring is provided between the inner magnetic conductive sleeve and the hollow rotating shaft.

8. The magnetic medium sealing device suitable for a hollow shaft according to claim 7, characterized in that: The outer circumferential surface of the hollow rotating shaft is further provided with a third retaining spring arranged along its circumference, and the third retaining spring is clamped on the side of the outer magnetic sleeve facing away from the second permanent magnet; and / or, the inner circumferential surface of the hollow rotating shaft is further provided with a fourth retaining spring arranged along its circumference, and the fourth retaining spring is clamped on the side of the inner magnetic sleeve facing away from the second permanent magnet.

9. According to any one of claims 1 to 8, a magnetic medium sealing device suitable for a hollow shaft, the value of the first gap is determined based on the radial elongation caused by the centrifugal force caused by the rated speed of the hollow shaft, the value of the second gap is determined based on processing and assembly errors, and the value of the third gap is determined based on the optimal gap value of a traditional magnetic medium seal.

10. The magnetic medium sealing device suitable for a hollow shaft according to claim 1, characterized in that: A first groove is provided on the outer circumference of the hollow shaft, and the first pole tooth is arranged on the bottom wall of the first groove. A second groove is provided at the end of the hollow shaft, and the second pole tooth is arranged on the bottom wall of the second groove.

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