A step-pole tooth type magnetic fluid sealing device

Abstract

The application provides a stepped pole tooth type magnetic fluid sealing device. The stepped pole tooth type magnetic fluid sealing device comprises a shell, a rotating shaft, and an end cover. The middle part of the rotating shaft comprises a first shaft part, a second shaft part, and a third shaft part and forms a stepped shaft. A first pole shoe ring is sleeved on the first shaft part. A permanent magnet ring and a second pole shoe ring are sleeved on the second shaft part. The surface of the first pole shoe ring close to the second shaft part is provided with a plurality of stepped pole teeth. The surface of the second shaft part close to the first pole shoe ring is provided with a plurality of stepped grooves. The stepped pole teeth and the stepped grooves form a first leakage path. The surface of the second pole shoe ring close to the third shaft part is provided with a plurality of stepped pole teeth. The surface of the third shaft part close to the second pole shoe ring is provided with a plurality of stepped grooves. The stepped pole teeth and the stepped grooves form a second leakage path. The application increases the axial sealing gap and improves the pressure resistance of the sealing device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic fluid sealing, in particular to a stepped pole tooth type magnetic fluid sealing device. BACKGROUND

[0002] The magnetic fluid sealing device utilizes the unique magnetic response characteristics of the magnetic fluid, and through the application of a high-strength magnetic field, the magnetic fluid forms multiple "O" type sealing rings to resist the pressure on both sides. In the case of large shaft diameter and high speed, the ordinary magnetic fluid sealing structure has only a radial sealing gap, which results in low sealing pressure resistance and is difficult to meet the requirements of large shaft diameter and high speed. Therefore, improving the sealing performance under the condition of large shaft diameter and high speed is one of the current research focuses.

[0003] For example, the existing patent publication No. CN108468811A discloses a magnetic fluid sealing structure, which forms a stepped magnetic fluid sealing through the annular step and the pole shoe, so that sealing can be performed in the radial and axial directions, and has the conditions of realizing high sealing and high pressure resistance. However, the pole shoe structure reduces the volume of the permanent magnet, making it difficult to form a wide effective magnetic field, and the sealing structure does not have the condition of opening the pole teeth on the shaft, and cannot well overcome the influence of centrifugal force on the sealing performance, and is difficult to meet the sealing requirements under high speed conditions.

[0004] For example, the existing patent publication No. CN109185464B discloses a magnetic cylinder stepped magnetic fluid sealing device, which changes the sealing gap between the pole shoe and the shaft in the traditional magnetic fluid sealing device to a sealing gap between the pole shoe and the sleeve, and installs multiple permanent magnets inside the pole shoe, so that the magnetic fluid is adsorbed below the permanent magnet to form a liquid "O" ring to resist the pressure difference on both sides. The structure utilizes multiple permanent magnets to form a strong magnetic field environment, which can effectively improve the pressure resistance performance of the magnetic fluid sealing. However, the structure does not have the condition of opening the pole teeth on the shaft, and cannot overcome the influence of centrifugal force on the sealing performance of the magnetic fluid, and the number of permanent magnets is too large, increasing the complexity of the structure and the cost of materials.

[0005] In addition, in the existing magnetic fluid sealing device, the middle part of the shaft is mostly a cylindrical shaft structure, the leakage path is short, and the sealing form is single. SUMMARY

[0006] The present application aims to provide a stepped pole tooth type magnetic fluid sealing device which is suitable for large shaft diameter and high speed working conditions, has good sealing performance, simple structure and is not easy to fail.

[0007] The technical scheme of the present application is: a stepped pole tooth type magnetic fluid sealing device, comprising a hollow shell, a rotating shaft arranged in the inner cavity of the shell, and an end cover covering the open end of the shell, the middle part of the rotating shaft comprising a first shaft part, a second shaft part and a third shaft part arranged in sequence, the diameters of the first shaft part, the second shaft part and the third shaft part gradually increase to form a stepped shaft in the middle part of the rotating shaft; a first pole shoe ring is sleeved on the first shaft part; a permanent magnet ring and a second pole shoe ring are sleeved on the second shaft part, and the permanent magnet ring is embedded between the first pole shoe ring and the second pole shoe ring;

[0008] The surface of the first pole shoe ring near the second shaft part is provided with a plurality of stepped pole teeth, the surface of the second shaft part near the first pole shoe ring is provided with a plurality of stepped grooves, the plurality of stepped pole teeth and the plurality of stepped grooves are matched one by one, and the stepped pole teeth and the stepped grooves form a first leakage path.

[0009] The surface of the second pole shoe ring near the third shaft part is provided with a plurality of stepped pole teeth, the surface of the third shaft part near the second pole shoe ring is provided with a plurality of stepped grooves, the plurality of stepped pole teeth and the plurality of stepped grooves are matched one by one, and the stepped pole teeth and the stepped grooves form a second leakage path.

[0010] In the above scheme, the end face of the pole shoe is provided with stepped pole teeth, the shaft end surface is provided with stepped grooves, the stepped pole teeth and the stepped grooves are arranged oppositely, the end face of the stepped pole teeth and the corresponding end face of the stepped groove form a sealing gap, and the whole forms a stepped sealing structure, so that the magnetic fluid sealing device has stable sealing performance.

[0011] Preferably, a first ring tooth protruding towards the first shaft part is arranged on the inner hole wall of the first pole shoe ring, and a plurality of first ring teeth are arranged in the axial direction of the first pole shoe ring.

[0012] Preferably, the end of the first ring tooth and the first shaft part form a gap, and magnetic fluid is injected into the gap.

[0013] Preferably, a second ring tooth protruding towards the second shaft part is arranged on the inner hole wall of the second pole shoe ring, and a plurality of second ring teeth are arranged in the axial direction of the second pole shoe ring.

[0014] Preferably, the end of the second ring tooth and the second shaft part form a gap, and magnetic fluid is injected into the gap.

[0015] Preferably, a first magnetic separation ring is further sleeved on the first shaft part beside the first pole shoe ring, the outer surface of the first magnetic separation ring is in contact with the inner hole wall of the shell, a gap is arranged between the first magnetic separation ring and the first shaft part, and magnetic fluid is injected into the gap.

[0016] Preferably, a second magnetic isolation ring is fitted on the third shaft portion, located next to the second pole shoe ring. The outer surface of the second magnetic isolation ring contacts the inner wall of the housing. A gap is provided between the second magnetic isolation ring and the third shaft portion, and magnetic fluid is injected into the gap.

[0017] Preferably, the rotating shaft and the housing are connected by bearing assembly. The bearings are respectively located on the sides of the first shaft and the third shaft. One end of the second magnetic isolation ring is clearance-fitted with the third shaft, and the other end is embedded in the outer surface of the bearing.

[0018] Preferably, a second sealing ring is provided between the first pole shoe ring, the second pole shoe ring and the inner wall of the corresponding position of the housing.

[0019] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0020] 1. The stepped pole tooth type magnetohydrodynamic sealing device replaces the cylindrical shaft in the middle of the rotating shaft of the traditional sealing structure with a stepped shaft, which increases the axial sealing gap, improves the pressure resistance of the sealing device, and allows for the opening of pole teeth on the shaft.

[0021] Second, a stepped pole tooth is designed between the pole shoe and the shaft end face so that the entire axial clearance can become a leakage path. The increased leakage path space allows for more positions to be placed for liquid O-rings, thereby increasing the number of liquid O-rings and enabling the magnetohydrodynamic seal decoupling strand to have stable sealing performance. Attached Figure Description

[0022] Figure 1 A schematic diagram of the internal cross-sectional structure of the stepped pole tooth type magnetohydrodynamic sealing device provided by the present invention.

[0023] Figure 2 for Figure 1 Enlarged diagram of point A in the diagram;

[0024] Figure 3 for Figure 1 Enlarged diagram of point B in the image.

[0025] In the attached diagram: 1. First sealing ring; 2. Housing; 3. Rotating shaft; 31. First shaft portion; 32. Second shaft portion; 33. Third shaft portion; 4. Bearing; 5. First magnetic shielding ring; 6. Second sealing ring; 7. First pole shoe ring; 71. First ring tooth; 8. First leakage path; 9. Permanent magnet ring; 10. Second pole shoe ring; 101. Second ring tooth; 11. Second magnetic shielding ring; 12. End cap; 13. Second leakage path. 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 As shown, this embodiment provides a stepped pole tooth type magnetohydrodynamic sealing device including a hollow housing 2, a rotating shaft 3 disposed in the inner cavity of the housing 2, and an end cap 12 covering the open end of the housing 2. Both ends of the rotating shaft 3 are rotatably mounted to the housing 2 via bearings 4. The inner hole of the housing 2 is a two-stage stepped hole, with a bearing 4 and a first magnetic shielding ring 5 disposed in the smaller hole. A first pole shoe ring 7, a second pole shoe ring 10, and a second magnetic shielding ring 11 are sequentially disposed in the larger hole.

[0028] The middle part of the rotating shaft 3 includes a first shaft part 31, a second shaft part 32 and a third shaft part 33 arranged in sequence, and the diameters of the first shaft part 31, the second shaft part 32 and the third shaft part 33 increase sequentially, so that the middle part of the rotating shaft 3 forms a stepped shaft.

[0029] A first magnetic shielding ring 5 and a first pole shoe ring 7 are fitted onto the first shaft portion 31. The first magnetic shielding ring 5 abuts between the bearing 4 and the first pole shoe ring 7. The outer surface of the first magnetic shielding ring 5 contacts the inner wall of the housing 2. A gap is provided between the first magnetic shielding ring 5 and the first shaft portion 31, and magnetic fluid is injected into the gap.

[0030] like Figure 1 , Figure 2 As shown, the first pole shoe ring 7 is disposed with the second shaft portion 32, and the surface of the first pole shoe ring 7 near the second shaft portion 32 is provided with a plurality of stepped pole teeth, and the surface of the second shaft portion 32 near the first pole shoe ring 7 is provided with a plurality of stepped grooves. The plurality of stepped pole teeth and the plurality of stepped grooves cooperate one by one, and a first leakage path 8 is formed between the stepped pole teeth and the stepped grooves.

[0031] The inner wall of the first pole shoe ring 7 is provided with first ring teeth 71 protruding towards the first shaft portion 31, and multiple first ring teeth 71 are arranged in the axial direction of the first pole shoe ring 7. The end of the first ring teeth 71 forms a gap with the first shaft portion 31, and magnetic fluid is injected into the gap.

[0032] like Figure 1 , Figure 3As shown, a permanent magnet ring 9 and a second pole shoe ring 10 are fitted onto the second shaft portion 32, with the permanent magnet ring 9 embedded between the first pole shoe ring 7 and the second pole shoe ring 10. The second pole shoe ring 10 has multiple stepped pole teeth on its surface near the third shaft portion 33, and multiple stepped grooves on its surface near the second pole shoe ring 10. The multiple stepped pole teeth and the multiple stepped grooves engage one-to-one, forming a second leakage path 13 between the stepped pole teeth and the stepped grooves. Figure 2 As shown, the stepped electrode teeth in this embodiment have three rings, and the stepped electrode teeth in each ring are progressively protruding step-like structures, and the step-like structures are symmetrical vertically. The stepped grooves are adapted to the stepped electrode teeth, thereby forming a bent structure in the leakage path 8. Multiple bends can correspond to the placement of multiple liquid "O" rings, thereby increasing the number of liquid "O" rings and improving the sealing performance.

[0033] The inner wall of the second pole shoe ring 10 is provided with second ring teeth 101 protruding toward the second shaft portion 32, and multiple second ring teeth 101 are arranged in the axial direction of the second pole shoe ring 10. The end of the second ring teeth 101 forms a gap with the second shaft portion 32, and magnetic fluid is injected into the gap.

[0034] A second magnetic shielding ring 11 is fitted onto the third shaft portion 33, located beside the second pole shoe ring 10. The outer surface of the second magnetic shielding ring 11 contacts the inner wall of the housing 2. A gap is provided between the second magnetic shielding ring 11 and the third shaft portion 33, and magnetic fluid is injected into the gap. One end of the second magnetic shielding ring 11 has a gap with the third shaft portion 33, and the other end is embedded in the outer surface of the bearing 4.

[0035] Magnetizing fluid is injected into the axial gap between the first magnetic shielding ring 5, the first pole shoe ring 7 and the first shaft portion 31, the radial gap between the first pole shoe ring 7 and the second shaft portion 32, the permanent magnet ring 9, the axial gap between the second pole shoe ring 10 and the second shaft portion 32, the radial gap between the second pole shoe ring 10 and the third shaft portion 33, and the axial gap between the second magnetic shielding ring 11 and the third shaft portion 33.

[0036] A first sealing ring 1 is provided on the surface of the closed end of the housing 2. A second sealing ring 6 is provided between the first magnetic shielding ring 5, the first pole shoe ring 5, the second pole shoe ring 10, and the second magnetic shielding ring 11 and the inner wall of the corresponding position of the housing 2. Both the first sealing ring 1 and the second sealing ring 6 are O-rings. The bearing 4 is a deep groove ball bearing.

[0037] The stepped pole tooth type magnetohydrodynamic (MHD) sealing device provided by this invention can solve the problems of poor sealing effect and severe detachment of magnetohydrodynamic (MHD) fluid from the sealing gap under large shaft diameter conditions in existing MHD sealing devices. By designing the middle part of the rotating shaft as a stepped shaft, the axial sealing gap is increased, improving the pressure resistance of the sealing device. By setting a stepped pole tooth engagement method between the pole shoe and the shaft end, the entire axial gap becomes a leakage path, significantly increasing the number of liquid O-rings; thus, the MHD sealing structure has stable sealing performance.

[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 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 step-pole tooth type magnetic fluid sealing device, comprising a hollow housing (2), a rotating shaft (3) arranged in the inner cavity of the housing (2), and an end cover (12) covering the open end of the housing (2), characterized in that, The middle part of the rotating shaft (3) comprises a first shaft part (31), a second shaft part (32) and a third shaft part (33) arranged in sequence, the diameters of the first shaft part (31), the second shaft part (32) and the third shaft part (33) are sequentially increased, so that the middle part of the rotating shaft (3) forms an asymmetric stepped shaft; the first pole shoe ring (7) is sleeved on the first shaft part (31); the permanent magnet ring (9) and the second pole shoe ring (10) are sleeved on the second shaft part (32), and the permanent magnet ring (9) is embedded between the first pole shoe ring (7) and the second pole shoe ring (10); The surface of the second shaft part (32) close to the first pole shoe ring (7) is provided with a plurality of stepped teeth, the surface of the first pole shoe ring (7) close to the second shaft part (32) is provided with a plurality of stepped grooves, the plurality of stepped teeth and the plurality of stepped grooves are one-to-one matched, and the first leakage path (8) is formed between the stepped teeth and the stepped grooves; The surface of the third shaft part (33) close to the second pole shoe ring (10) is provided with a plurality of stepped teeth, the surface of the second pole shoe ring (10) close to the third shaft part (33) is provided with a plurality of stepped grooves, the plurality of stepped teeth and the plurality of stepped grooves are one-to-one matched, and the second leakage path (13) is formed between the stepped teeth and the stepped grooves; The stepped teeth are provided with three circles, the stepped teeth in each circle are in a stepped structure which is protruded step by step and symmetrical in up and down directions, the stepped grooves are matched with the stepped teeth, the first leakage path (8) and the second leakage path (13) form a bent structure, and a plurality of bends can correspond to a plurality of liquid "O" rings.

2. The stepped pole tooth magnetic fluid seal of claim 1, wherein, The inner hole wall of the first pole shoe ring (7) is provided with a first ring tooth (71) protruding towards the first shaft part (31), and a plurality of first ring teeth (71) are arranged in the axial direction of the first pole shoe ring (7).

3. The stepped pole tooth magnetic fluid seal of claim 2, wherein, The end of the first ring tooth (71) and the first shaft part (31) form a gap, and the gap is filled with magnetic fluid.

4. The stepped pole tooth magnetic fluid seal of claim 1, wherein, The inner hole wall of the second pole shoe ring (10) is provided with a second ring tooth (101) protruding towards the second shaft part (32), and a plurality of second ring teeth (101) are arranged in the axial direction of the second pole shoe ring (10).

5. The stepped pole tooth magnetic fluid seal of claim 4, wherein, The end of the second ring tooth (101) and the second shaft part (32) form a gap, and the gap is filled with magnetic fluid.

6. The stepped pole tooth magnetic fluid seal of claim 1, wherein, The first magnetic shielding ring (5) is sleeved on the first shaft part (31) beside the first pole shoe ring (7), the outer surface of the first magnetic shielding ring (5) is in contact with the inner hole wall of the shell (2), a gap is formed between the first magnetic shielding ring (5) and the first shaft part (31), and the gap is filled with magnetic fluid.

7. The stepped pole tooth magnetic fluid seal of claim 1, wherein, The second magnetic shielding ring (11) is sleeved on the third shaft part (33) beside the second pole shoe ring (10), the outer surface of the second magnetic shielding ring (11) is in contact with the inner hole wall of the shell (2), a gap is formed between the second magnetic shielding ring (11) and the third shaft part (33), and the gap is filled with magnetic fluid.

8. The stepped pole tooth magnetic fluid seal of claim 7, wherein, The rotating shaft (3) is assembled and connected with the shell (2) through a bearing (4), the bearing (4) is arranged on the side of the first shaft part (31) and the third shaft part (33), one end of the second magnetic isolation ring (11) is in gap cooperation with the third shaft part (33), and the other end is embedded with the outer surface of the bearing (4).

9. The stepped pole tooth magnetic fluid seal of claim 1, wherein, The first pole shoe ring (7) and the second pole shoe ring (10) are provided with the second sealing ring (6) between the inner hole walls of the corresponding positions of the shell (2).

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