A multi-magnetic circuit magnetic fluid sealing device for high vacuum

Abstract

The application provides a multi-magnetic-circuit magnetic fluid sealing device for high vacuum. The sealing device comprises a rotating shaft, a shell, an end cover, pole shoes, sleeves and a second inner permanent magnet ring, the second inner permanent magnet ring is arranged in the middle of the rotating shaft, the sleeves are symmetrically arranged on the two sides of the second inner permanent magnet ring, the pole shoes are symmetrically arranged on the outer sides of the sleeves, the pole shoes and the rotating shaft form a meandering first channel, the pole shoes and the sleeves form a meandering second channel, the first channel and the second channel are communicated and symmetric; a magnetic isolation sleeve, a first inner permanent magnet ring and an outer permanent magnet ring are sleeved on the second inner permanent magnet ring; the first inner permanent magnet ring and the second inner permanent magnet ring have the same magnetic poles, and the first inner permanent magnet ring and the outer permanent magnet ring have opposite magnetic poles. The application solves the sealing problems of poor sealing effect, low vacuum degree and the like under the high vacuum working condition of the traditional magnetic fluid sealing device.

Description

Technical Field

[0001] This invention relates to the field of mechanical engineering sealing technology, and in particular to a multi-magnetic-circuit magnetohydrodynamic sealing device for high vacuum applications. Background Technology

[0002] Magnetofluidic sealing devices utilize the unique magnetic response characteristics of magnetofluids. By applying a high-strength magnetic field, multiple magnetofluid liquid films are formed to resist pressure from both sides. Under high vacuum conditions, conventional magnetofluidic sealing structures rarely achieve high vacuum levels and exhibit high leakage rates. Therefore, improving sealing performance under high vacuum conditions is currently a research hotspot.

[0003] Traditional magnetohydrodynamic (MHD) sealing devices often employ cylindrical shaft structures, resulting in short leakage paths and limited sealing methods. Under high vacuum conditions, conventional MHD sealing structures rarely achieve high vacuum levels and exhibit high leakage rates. Therefore, improving sealing performance under high vacuum conditions is currently a hot research topic.

[0004] Existing patents, such as CN108006233B, disclose a magnetohydrodynamic sealing structure with a trapezoidal pole shoe sleeve. This structure forms a sealing gap between the trapezoidal sleeve and the pole shoe, and multiple magnetohydrodynamic films are formed under the magnetic field of three permanent magnets within the trapezoidal sleeve, achieving a sealing effect. However, this structure suffers from significant magnetic source waste and fails to adequately address magnetic leakage, thus failing to meet the practical requirements of high-vacuum conditions.

[0005] For example, patent publication number CN 109027252B discloses a bifurcated magnetohydrodynamic (MHD) sealing structure. This structure utilizes a bifurcated sleeve and the inclined surface of the pole shoe to form a sealing gap. This inclined sealing gap effectively solves the problems of large centrifugal force and easy carryover of magnetohydrodynamic fluid inherent in straight-through sealing gaps, thus effectively improving the pressure resistance of the MHD seal. However, this structure forms a relatively small number of magnetohydrodynamic liquid films and is difficult to process.

[0006] Therefore, there is an urgent need for a magnetohydrodynamic sealing device that is adaptable to high vacuum conditions, has good sealing performance, simple structure, and is not prone to failure. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-magnetic-circuit magnetofluid sealing device for high vacuum, which solves the sealing problems of poor sealing effect and low achievable vacuum degree of traditional magnetofluid sealing devices under high vacuum conditions.

[0008] The technical solution of the present invention is as follows: A high vacuum multi-magnetic circuit magnetohydrodynamic sealing device includes a rotating shaft, a housing, an end cap, a pole shoe, a sleeve, and a second inner permanent magnet ring, which are installed inside the housing and mounted on the rotating shaft. The end cap is connected to one end of the housing. The rotating shaft passes through the housing and the end cap. The second inner permanent magnet ring is located in the middle of the rotating shaft. The sleeve is symmetrically arranged on both sides of the second inner permanent magnet ring. The pole shoe is symmetrically arranged on the outside of the sleeve. A meandering first channel is formed between the pole shoe and the rotating shaft. A meandering second channel is formed between the pole shoe and the sleeve. The first channel and the second channel are connected. The first channel and the second channel are symmetrically arranged on both sides of the second inner permanent magnet ring.

[0009] The outer ring of the second inner permanent magnet ring is fitted with a magnetic shielding cylinder and a first inner permanent magnet ring from the inside out. The outer ring of the first inner permanent magnet ring is fitted with an outer permanent magnet ring at intervals. The interval between the first inner permanent magnet ring and the outer permanent magnet ring forms the second channel. The first inner permanent magnet ring and the second inner permanent magnet ring have the same magnetic poles, while the first inner permanent magnet ring and the outer permanent magnet ring have opposite magnetic poles.

[0010] Preferably, the first channel and the second channel form a "Z" shape.

[0011] Preferably, the second channel includes a horizontal segment parallel to the first channel and an inclined segment obliquely connected between the first channel and the horizontal segment;

[0012] The pole shoe has multiple first pole teeth on the side facing the sleeve, and the multiple first pole teeth are located in the inclined section; the sleeve has multiple third pole teeth on the side facing the pole shoe, and the multiple third pole teeth are provided in both the inclined section and the horizontal section. The first pole teeth and the third pole teeth are spaced apart to form a second channel, and the third pole teeth are spaced apart from the inner wall of the pole shoe to form the second channel.

[0013] Preferably, among the plurality of first pole teeth and third pole teeth, the first pole teeth and third pole teeth located in odd-numbered positions are staggered, and the first pole teeth and third pole teeth located in even-numbered positions are aligned.

[0014] Preferably, the pole shoe has a plurality of second pole teeth on the side facing the rotating shaft, and the second pole teeth are spaced apart from the rotating shaft to form the first channel.

[0015] Preferably, the sleeve and the second inner permanent magnet ring are threadedly connected to the rotating shaft.

[0016] Preferably, a sealing ring is provided between the pole shoe and the inner wall of the housing.

[0017] Preferably, the rotating shaft is mounted inside the housing via a deep groove ball bearing, and the deep groove ball bearing is located at both ends of the pole shoe.

[0018] Preferably, a magnetic shielding ring is provided between the deep groove ball bearing and the pole shoe.

[0019] Preferably, the end cap is threadedly connected to the housing.

[0020] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0021] I. This invention divides the magnetic circuit into two parts by adding a magnetic shielding cylinder in the middle of the rotating shaft and aligning the magnetic poles: a permanent magnet ring, left and right pole shoes, left and right sleeves, a first inner permanent magnet ring, and a second inner permanent magnet ring, which is the rotating shaft. This effectively solves the problems of severe magnetic leakage and weak magnetic induction intensity in a single magnetic circuit and enhances the pressure resistance of the sealing device.

[0022] Second, the third pole tooth on the sleeve and the first pole tooth on the pole shoe form an alternating staggered tooth structure. This structure enables the magnetic field lines passing through the two pole teeth to pass through a more concentrated diagonal, which greatly improves the critical pressure resistance of the magnetohydrodynamic film.

[0023] Third, the second channel forms a "Z"-shaped labyrinth seal, in which the third tooth of the sleeve and the first tooth of the pole shoe form a centered labyrinth loop inlet. Compared with the bottom-mounted labyrinth loop inlet, it can effectively reduce the influence of the "breathing effect" and enhance the function of the labyrinth seal. Attached Figure Description

[0024] Figure 1 A schematic diagram of the internal structure of the high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device provided by the present invention;

[0025] Figure 2 for Figure 1 Enlarged diagram of point A in the diagram. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0027] like Figure 1 , Figure 2 As shown, the high vacuum multi-magnetic circuit magnetohydrodynamic sealing device provided in this embodiment includes a rotating shaft 1, a housing 2, a deep groove ball bearing 3, a magnetic shielding ring 4, a pole shoe 5, a sleeve 6, an outer permanent magnet ring 7, a second inner permanent magnet ring 8, a first inner permanent magnet ring 9, a first channel 10, a magnetic shielding cylinder 11, a second channel 12, a first pole tooth 13, a second pole tooth 14, a third pole tooth 15, and an end cap 16.

[0028] The end cap 16 is threaded to one end of the housing 2, and the rotating shaft 1 passes through the housing 2 and the end cap 16. A pole shoe 5, a sleeve 6, and a second inner permanent magnet ring 8 are fitted into the middle of the rotating shaft 1. The second inner permanent magnet ring 8 is positioned in the middle of the rotating shaft 1, and a sleeve 6 is provided on each side of the second inner permanent magnet ring 8, with the two sleeves 6 arranged symmetrically. Each sleeve 6 has an inclined surface and a flat surface; one end of the inclined surface is close to the rotating shaft, and the other end slopes outward and connects to the flat surface. The flat surface is parallel to the centerline of the rotating shaft 1.

[0029] The pole shoes 5 are fitted on the outer sides of both sleeves 6. The side of the pole shoe 5 closest to the sleeve 6 is also provided with an inclined surface and a flat surface. The inclined surface of the pole shoe 5 corresponds to and is parallel to the inclined surface on the sleeve 6, and the flat surface of the pole shoe 5 corresponds to and is parallel to the flat surface on the sleeve 6.

[0030] A meandering first channel 10 is formed between the pole shoe 5 and the rotating shaft 1, and a meandering second channel 12 is formed between the pole shoe 5 and the sleeve 6. The first channel 10 and the second channel 12 are connected, and the first channel 10 and the second channel 12 are symmetrically arranged on both sides of the second inner permanent magnet ring 8. The structure of the inclined surface and the plane makes the first channel 10 and the second channel 12 on one side form a "Z" shape. That is, the second channel 12 includes a horizontal section parallel to the first channel 10 and an inclined section that is inclinedly connected between the first channel 10 and the horizontal section.

[0031] The pole shoe 5 has multiple first pole teeth 13 on the side facing the sleeve 6, and these first pole teeth 13 are located on the inclined section (i.e., on the inclined surface of the pole shoe 5). The sleeve 6 has multiple third pole teeth 15 on the side facing the pole shoe 5, and these third pole teeth 15 are provided on both the inclined section and the horizontal section (i.e., on both the inclined surface and the horizontal surface of the sleeve 6). The first pole teeth 13 and the third pole teeth 15 are spaced apart to form a second channel 12, and the third pole teeth 15 are spaced apart from the inner wall of the pole shoe 5 to form the second channel 12. The first pole teeth 13 and the third pole teeth 15 make the second channel 12 form a meandering structure.

[0032] In this embodiment, among the multiple first pole teeth 13 and third pole teeth 15 on the inclined section of the second channel 12, the section closest to the horizontal section is designated as starting 1. Therefore, the first pole teeth 13 and third pole teeth 15 located in odd-numbered positions are staggered, while those located in even-numbered positions are aligned. This alternating staggered tooth structure allows the magnetic field lines passing through the two pole teeth to pass through a more concentrated diagonal path, significantly improving the critical pressure resistance of the magnetohydrodynamic film.

[0033] The pole shoe 5 has multiple second pole teeth 14 on the side facing the rotating shaft 1, and the first channel 12 is formed between the second pole teeth 14 and the rotating shaft 1 at intervals. The first channel 12 forms a meandering structure through the multiple second pole teeth 14.

[0034] The outer ring of the second inner permanent magnet ring 8 is fitted with a magnetic shielding cylinder 11 and a first inner permanent magnet ring 9 sequentially from the inside out. An outer permanent magnet ring 7 is fitted around the outer ring of the first inner permanent magnet ring 9 at a distance. The gap between the first inner permanent magnet ring 9 and the outer permanent magnet ring 7 forms the second channel 12. The first inner permanent magnet ring 9 and the second inner permanent magnet ring 8 have the same magnetic poles, while the first inner permanent magnet ring 9 and the outer permanent magnet ring 7 have opposite magnetic poles.

[0035] By adding a magnetic shielding cylinder 11 in the middle of the rotating shaft 1 and using opposing magnetic poles (opposite stimulation), the magnetic circuit is divided into two parts: a permanent magnet ring—left and right pole shoes—left and right sleeves—first inner permanent magnet ring; and a second inner permanent magnet ring—rotating shaft. This effectively solves the problems of severe magnetic leakage and weak magnetic induction intensity in a single magnetic circuit, and enhances the pressure resistance of the sealing device.

[0036] The rotating shaft 1 is mounted inside the housing 2 via deep groove ball bearings 3, with the deep groove ball bearings 3 located at both ends of the pole shoes 5. The deep groove ball bearings 3 are mounted on the rotating shaft 1 with an interference fit. A magnetic isolation ring 4 is provided between the deep groove ball bearings 3 and the pole shoes 5. The sleeve 6 and the rotating shaft 1, as well as the second inner permanent magnet ring 8 and the rotating shaft 1, are all threadedly connected. A sealing ring 15 is provided between the pole shoes 5 and the inner wall of the housing 2. The end cap 14 is threadedly connected to the housing 2.

[0037] This invention presents a novel labyrinthine magnetohydrodynamic (MHD) sealing structure that meets the sealing requirements of vacuum conditions and exhibits excellent performance. By adding a non-magnetic shielding cylinder 11 and an inner and outer permanent magnet ring with opposing magnetic poles, the original overall magnetic circuit is divided into two parts, effectively preventing magnetic leakage and increasing magnetic induction intensity. The oblique third pole tooth 15 on the sleeve 6 and the oblique first pole tooth 13 on the pole shoe 5 form an alternating staggered tooth structure, concentrating magnetic lines of force at the diagonal, significantly improving the critical pressure resistance of the MHD film. The first channel 10 and the second channel 12 form a "Z"-shaped labyrinthine seal, where the oblique third pole tooth 15 on the sleeve 6 and the oblique first pole tooth 13 on the pole shoe 5 form a centered labyrinthine circuit inlet. Compared to a ground-mounted labyrinthine circuit inlet, this effectively reduces the impact of "air permeability" and enhances the effect of the labyrinthine seal.

[0038] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device, comprising a rotating shaft (1), a housing (2), and an end cap (16), wherein the end cap (16) is connected to one end of the housing (2), and the rotating shaft (1) passes through the housing (2) and the end cap (16), characterized in that, It also includes a pole shoe (5), a sleeve (6), and a second inner permanent magnet ring (8) inside the housing (2) and fitted on the rotating shaft (1). The second inner permanent magnet ring (8) is located in the middle of the rotating shaft (1). The sleeve (6) is symmetrically arranged on both sides of the second inner permanent magnet ring (8). The pole shoe (5) is symmetrically arranged on the outside of the sleeve (6). A meandering first channel (10) is formed between the pole shoe (5) and the rotating shaft (1). A meandering second channel (12) is formed between the pole shoe (5) and the sleeve (6). The first channel (10) and the second channel (12) are connected. The first channel (10) and the second channel (12) are symmetrically arranged on both sides of the second inner permanent magnet ring (8). The outer ring of the second inner permanent magnet ring (8) is fitted with a magnetic shielding cylinder (11) and a first inner permanent magnet ring (9) from the inside out. The outer ring of the first inner permanent magnet ring (9) is fitted with an outer permanent magnet ring (7) at intervals. The interval between the first inner permanent magnet ring (9) and the outer permanent magnet ring (7) forms the second channel (12). The first inner permanent magnet ring (9) and the second inner permanent magnet ring (8) have the same magnetic poles, and the first inner permanent magnet ring (9) and the outer permanent magnet ring (7) have opposite magnetic poles.

2. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, The first channel (10) and the second channel (12) form a "Z" shape.

3. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, The second channel (12) includes a horizontal segment parallel to the first channel (10) and an inclined segment obliquely connected between the first channel (10) and the horizontal segment; The pole shoe (5) has a plurality of first pole teeth (13) on the side facing the sleeve (6), and the plurality of first pole teeth (13) are located in the inclined section; the sleeve (6) has a plurality of third pole teeth (15) on the side facing the pole shoe (5), and the plurality of third pole teeth (15) are provided in both the inclined section and the horizontal section. The first pole teeth (13) and the third pole teeth (15) are spaced apart to form the second channel (12), and the third pole teeth (15) are spaced apart from the inner wall of the pole shoe (5) to form the second channel (12).

4. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 3, characterized in that, Among the multiple first pole teeth (13) and third pole teeth (15), the first pole teeth (13) and third pole teeth (15) located in odd-numbered positions are staggered, while the first pole teeth (13) and third pole teeth (15) located in even-numbered positions are aligned.

5. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, The pole shoe (5) has a plurality of second pole teeth (14) on the side facing the rotating shaft (1), and the second pole teeth (14) and the rotating shaft (1) are spaced apart to form the first channel (10).

6. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, The sleeve (6) and the second inner permanent magnet ring (8) are threadedly connected to the rotating shaft (1).

7. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, A sealing ring is provided between the pole shoe (5) and the inner wall of the housing (2).

8. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, The rotating shaft (1) is installed inside the housing (2) via a deep groove ball bearing (3), and the deep groove ball bearing (3) is located at both ends of the pole shoe (5).

9. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 8, characterized in that, A magnetic isolation ring (4) is provided between the deep groove ball bearing (3) and the pole shoe (5).

10. The high-vacuum multi-magnetic-circuit magnetohydrodynamic sealing device according to claim 1, characterized in that, The end cap (16) is threadedly connected to the housing (2).

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