A magnetic liquid sealing device with wide temperature applicability

Abstract

A magnetic liquid sealing device with wide temperature applicability comprises a rotating shaft (11), a housing (12), a bearing part (13), and a magnetic liquid sealing part (14); the magnetic liquid A (1409, 1411) is a fluorocarbon-based or ester-based magnetic liquid, and the magnetic liquid B (1410) is a kerosene-based or engine oil-based magnetic liquid; the magnetic liquid A (1409) is injected into the pole teeth (1406) corresponding to the pole shoes (1403) adjacent to the sealed space, and the magnetic liquid B (1410) is injected into at least one stage of the pole teeth (1407, 1408) corresponding to the other pole shoes (1404, 1405). With this structure, the magnetic liquid sealing device has low rotation torque under low temperature conditions and low volatility under high temperature conditions. The sealing device effectively prevents the contamination of the sealed space caused by the evaporation of the magnetic liquid, and because the evaporation amount of the magnetic liquid to the outside is reduced, the evaporation loss of the magnetic liquid is reduced, and the maintenance period and service life of the magnetic liquid sealing device are indirectly extended.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical engineering sealing, and is particularly suitable for sealing at a temperature below -40°C and above 60°C in the fields of military industry, shipbuilding, navigation, aerospace, etc. Background Art

[0002] Magnetic liquid is a new type of functional material. It is a stable colloidal solution formed by uniformly dispersing nano-scale magnetic solid particles in a base carrier liquid. One of the most important applications of magnetic liquid is magnetic liquid seal. Magnetic liquid seal has a tight seal, and its leakage rate is almost difficult to measure; and because it is a non-contact seal, it has a long life, high reliability, and can withstand high speed.

[0003] In actual use, some special fields require magnetic liquids to work in a wide temperature range from below -40°C to above 60°C. Under low temperature conditions, especially below -40°C, the viscosity of the magnetic liquid increases sharply, causing the rotation torque of the rotating shaft to be too large, which cannot meet the precision control requirements of the equipment and even destroys the electric drive system. To solve this technical problem, a low-temperature large-diameter magnetic liquid sealing device disclosed in the Chinese invention patent specification CN1245583C uses a magnetic liquid with good low-temperature fluidity, such as a kerosene-based magnetic liquid, as a sealing medium. This technical solution overcomes the disadvantage of excessive rotation torque under low temperature conditions, but under high temperature conditions, especially above 60°C, since magnetic liquids with good low-temperature fluidity often have strong volatility, they cannot meet certain occasions with high requirements for volatility.

[0004] Therefore, how to make the magnetic liquid sealing device have both low rotational torque and low volatility in a wide temperature range has become an urgent problem that needs to be solved. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the prior art cannot have both low rotational torque and low volatility in a wide temperature range. Therefore, a magnetic liquid sealing device with wide temperature applicability is provided, so that the magnetic liquid sealing device has low rotational torque under low temperature conditions and low volatility under high temperature conditions.

[0006] The technical solution of the present invention is to design a magnetic liquid sealing structure according to the requirements of rotational torque and volatility under wide temperature range conditions, and select a magnetic liquid with low viscosity and high volatility and a magnetic liquid with high viscosity and low volatility for combined sealing.

[0007] A magnetic liquid sealing device with wide temperature applicability comprises: a rotating shaft, a housing, a bearing part, and a magnetic liquid sealing part. The housing is made of a non-magnetic material, and a flange assembly is provided on the housing for the installation of the sealing device and the sealing of the installation connection. An end cover is installed at the end of the housing, and the end cover is preferably connected to the housing by threads or bolts. The bearing of the bearing part is installed in the housing, and the rotating shaft cooperates with the bearing part and penetrates the housing along the axial direction of the housing. The magnetic liquid sealing part consists of a permanent magnet, a pole shoe, a pole tooth, a magnetic liquid, a sealing ring, and a magnetic isolation ring. The pole shoe, the pole tooth, and the rotating shaft are made of magnetic conductive materials. The pole tooth is a groove of a certain size, which is opened on the pole shoe or the rotating shaft, exists in the gap formed by the pole shoe and the rotating shaft, and is used to form a magnetic field gradient. The number of pole teeth at each level may be different. The permanent magnet is installed between the pole shoes at each level as a magnetic source, and the magnetic liquid is adsorbed on the pole teeth to form multiple magnetic liquid rings. The permanent magnet, pole shoe, pole teeth, rotating shaft and magnetic liquid form a closed magnetic circuit, and the magnetic liquid has pressure resistance under the action of magnetic field gradient, so that the sealing gap at the pole teeth can be reliably sealed. A groove is provided on the outer periphery of the pole shoe, and the sealing ring is embedded in the groove to seal the leakage channel between the pole shoe and the housing. The magnetic isolation ring is made of non-magnetic material and cooperates with the pole shoe to prevent magnetic leakage in the magnetic circuit.

[0008] In the present invention, two magnetic liquids with different physical parameters are used for combined sealing. Magnetic liquid A is a magnetic liquid with higher viscosity under low temperature conditions and lower volatility under high temperature conditions; magnetic liquid B is a magnetic liquid with lower viscosity under low temperature conditions and higher volatility under high temperature conditions. Preferably, magnetic liquid A is a fluorocarbon-based or ester-based magnetic liquid, and magnetic liquid B is a kerosene-based or engine oil-based magnetic liquid.

[0009] The number of pole shoes is two or more, preferably two or three. Magnetic liquid A is injected into the pole teeth corresponding to the pole shoes adjacent to the sealed space, and magnetic liquid B is injected into at least one of the pole teeth corresponding to the other pole shoes. When the number of pole shoes is three or more, magnetic liquid A is preferably injected into the pole teeth corresponding to the pole shoes adjacent to the open space. The magnetic liquid A at the pole teeth corresponding to the pole shoes adjacent to the sealed space blocks the evaporation of magnetic liquid B to the sealed space, and the magnetic liquid A at the pole teeth corresponding to the pole shoes adjacent to the open space blocks the evaporation of magnetic liquid B to the open space, thereby preventing the magnetic liquid B from polluting the sealed space and the open space. In addition, since the evaporation amount of the magnetic liquid to the outside is reduced, the evaporation loss of the magnetic liquid is reduced, which indirectly prolongs the maintenance period and service life of the magnetic liquid sealing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein:

[0011] Figure 1 It is a structural cross-sectional view of a first embodiment of the present invention;

[0012] Figure 2 It is a structural cross-sectional view of a second embodiment of the present invention;

[0013] Figure 3 It is a structural cross-sectional view of a third embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to better understand the improvements made by the present invention relative to the prior art, three specific implementation modes of the present invention are described in detail below.

[0015] like Figure 1 In the first embodiment of the present invention shown, the wide temperature applicability magnetic liquid sealing device 1 includes: a rotating shaft 11, a housing 12, a bearing part 13, and a magnetic liquid sealing part 14. The housing 12 is made of a non-magnetic material, and a flange assembly 121 is provided on the housing 12. An end cover 122 is installed at the end of the housing 12, and the end cover 122 is connected to the housing 12 by threads. The bearings 131 and 132 of the bearing part 13 are installed in the housing 12, and the rotating shaft 11 cooperates with the bearing part 13 and penetrates the housing 12 axially along the housing 12. The magnetic liquid sealing part 14 is composed of a permanent magnet 1401, pole shoes 1403, 1404, pole teeth 1406, 1407, magnetic liquid A1409, magnetic liquid B1410, sealing rings 1412, 1413, and magnetic isolation rings 1415, 1416. Pole shoes 1403, 1404, pole teeth 1406, 1407, and rotating shaft 11 are made of magnetic conductive materials. Pole teeth 1406, 1407 are grooves of a certain size, which are opened on pole shoes 1403, 1404. Permanent magnet 1401 is installed between pole shoes 1403, 1404 as a magnetic source, and magnetic liquid 1409, 1410 is adsorbed on pole teeth 1406, 1407 to form multiple magnetic liquid rings. Permanent magnet 1401, pole shoes 1403, 1404, pole teeth 1406, 1407, rotating shaft 11 and magnetic liquid 1409, 1410 form a closed magnetic circuit. Grooves are opened on the outer periphery of pole shoes 1403, 1404, and sealing rings 1412, 1413 are embedded in the grooves. The magnetic isolation rings 1415 and 1416 are made of non-magnetic materials and cooperate with the pole shoes 1403 and 1404.

[0016] Magnetic liquid A1409 is injected into the pole teeth 1406 corresponding to the pole shoes adjacent to the sealed space, and magnetic liquid B1410 is injected into the pole teeth 1407 corresponding to the pole shoes adjacent to the open space. The magnetic liquid A1409 at the pole teeth 1406 corresponding to the pole shoes adjacent to the sealed space blocks the magnetic liquid B1410 from evaporating into the sealed space, thereby preventing the magnetic liquid B1410 from contaminating the sealed space.

[0017] like Figure 2In the second embodiment of the present invention shown, the magnetic liquid sealing device 1 with wide temperature applicability includes: a rotating shaft 11, a housing 12, a bearing part 13, and a magnetic liquid sealing part 14. The housing 12 is made of a non-magnetic material, and a flange assembly 121 is provided on the housing 12. An end cover 122 is installed at the end of the housing 12, and the end cover 122 is connected to the housing 12 by threads. The bearings 131 and 132 of the bearing part 13 are installed in the housing 12, and the rotating shaft 11 cooperates with the bearing part 13 and penetrates the housing 12 axially along the housing 12. The magnetic liquid sealing part 14 is composed of a permanent magnet 1401, pole shoes 1403, 1404, pole teeth 1406, 1407, magnetic liquid A1409, magnetic liquid B1410, sealing rings 1412, 1413, and magnetic isolation rings 1415, 1416. Pole shoes 1403, 1404, pole teeth 1406, 1407, and rotating shaft 11 are made of magnetic conductive materials. Pole teeth 1406, 1407 are grooves of a certain size, which are opened on rotating shaft 11 and correspond to pole shoes 1403, 1404. Permanent magnet 1401 is installed between pole shoes 1403, 1404 as a magnetic source, and magnetic liquid 1409, 1410 is adsorbed on pole teeth 1406, 1407 to form multiple magnetic liquid rings. Permanent magnet 1401, pole shoes 1403, 1404, pole teeth 1406, 1407, rotating shaft 11 and magnetic liquid 1409, 1410 form a closed magnetic circuit. Grooves are opened on the outer periphery of pole shoes 1403, 1404, and sealing rings 1412, 1413 are embedded in the grooves. The magnetic isolation rings 1415 and 1416 are made of non-magnetic materials and cooperate with the pole shoes 1403 and 1404.

[0018] Magnetic liquid A1409 is injected into the pole teeth 1406 corresponding to the pole shoes adjacent to the sealed space, and magnetic liquid B1410 is injected into the pole teeth 1407 corresponding to the pole shoes adjacent to the open space. The magnetic liquid A1409 at the pole teeth 1406 corresponding to the pole shoes adjacent to the sealed space blocks the magnetic liquid B1410 from evaporating into the sealed space, thereby preventing the magnetic liquid B1410 from contaminating the sealed space.

[0019] like Figure 3In the third embodiment of the present invention shown, the magnetic liquid sealing device 1 with wide temperature applicability includes: a rotating shaft 11, a housing 12, a bearing part 13, and a magnetic liquid sealing part 14. The housing 12 is made of a non-magnetic material, and a flange assembly 121 is provided on the housing 12. An end cover 122 is installed at the end of the housing 12, and the end cover 122 is connected to the housing 12 by threads. The bearings 131 and 132 of the bearing part 13 are installed in the housing 12, and the rotating shaft 11 cooperates with the bearing part 13 and penetrates the housing 12 axially along the housing 12. The magnetic liquid sealing part 14 is composed of permanent magnets 1401 and 1402, pole shoes 1403 to 1405, pole teeth 1406 to 1408, magnetic liquid A 1409 and 1411, magnetic liquid B 1410, sealing rings 1412 to 1414, and magnetic isolation rings 1415 and 1416. Pole shoes 1403-1405, pole teeth 1406-1408, and rotating shaft 11 are made of magnetic conductive materials. Pole teeth 1406-1408 are grooves of a certain size, which are opened on pole shoes 1403-1405. Permanent magnets 1401 and 1402 are installed between pole shoes 1403 and 1404 and between pole shoes 1404 and 1405 as magnetic sources, and magnetic liquids 1409-1411 are adsorbed on pole teeth 1406-1408 to form multiple magnetic liquid rings. Permanent magnets 1401, 1402, pole shoes 1403-1405, pole teeth 1406-1408, rotating shaft 11 and magnetic liquids 1409-1411 form a closed magnetic circuit. Grooves are opened on the outer periphery of pole shoes 1403-1405, and sealing rings 1412-1414 are embedded in the grooves. The magnetic isolation rings 1415 and 1416 are made of non-magnetic materials and cooperate with the pole shoes 1403 and 1405.

[0020] Magnetic liquid A1409 is injected into the pole tooth 1406 corresponding to the pole shoe adjacent to the sealed space, magnetic liquid A1411 is injected into the pole tooth 1408 corresponding to the pole shoe adjacent to the open space, and magnetic liquid B1410 is injected into the middle pole tooth 1407. The magnetic liquid A1409 at the pole tooth 1406 corresponding to the pole shoe adjacent to the sealed space blocks the magnetic liquid B1410 from evaporating into the sealed space, and the magnetic liquid A1411 at the pole tooth 1408 corresponding to the pole shoe adjacent to the open space blocks the magnetic liquid B1410 from evaporating into the open space, thereby preventing the magnetic liquid B1410 from contaminating the sealed space and the open space.

Claims

1. A magnetic liquid sealing device with wide temperature applicability, comprising: - a rotating shaft (11), a housing (12), a bearing portion (13), and a magnetic liquid sealing portion (14); - the housing (12) is made of a non-magnetic material, a flange assembly (121) is provided on the housing (12), and an end cover (122) is installed at the end of the housing (12); - the bearings (131, 132) of the bearing portion (13) are installed in the housing (12), and the rotating shaft (11) cooperates with the bearing portion (13) and penetrates the housing (12) axially along the housing (12); - The magnetic liquid sealing part (14) is composed of permanent magnets (1401, 1402), pole shoes (1403-1405), pole teeth (1406-1408), magnetic liquid A (1409, 1411), magnetic liquid B (1410), sealing rings (1412-1414), and magnetic isolation rings (1415, 1416); - the pole shoes (1403-1405), the pole teeth (1406-1408) and the rotating shaft (11) are made of magnetic conductive materials; - the pole teeth (1406-1408) are grooves of a certain size, which are provided on the pole shoes (1403-1405) or the rotating shaft (11), and exist in the gap formed by the pole shoes (1403-1405) and the rotating shaft (11); - Permanent magnets (1401, 1402) are installed between the pole shoes (1403-1405) as magnetic sources, and magnetic liquids (1409-1411) are adsorbed on the pole teeth (1406-1408) to form multiple magnetic liquid rings; - The permanent magnets (1401, 1402), the pole shoes (1403-1405), the pole teeth (1406-1408), the rotating shaft (11) and the magnetic liquid (1409-1411) form a closed magnetic circuit; - the pole shoes (1403-1405) have a level of two or more, a groove is provided on the outer circumference of the pole shoes (1403-1405), and the sealing rings (1412-1414) are embedded in the groove; - the magnetic isolation rings (1415, 1416) are made of non-magnetic materials and matched with the pole shoes (1403-1405); Features: - the magnetic liquid A (1409, 1411) is a fluorocarbon-based or ester-based magnetic liquid, and the magnetic liquid B (1410) is a kerosene-based or motor oil-based magnetic liquid; - A magnetic liquid A (1409) is injected into the pole teeth (1406) corresponding to the pole shoes (1403) adjacent to the sealed space, and a magnetic liquid B (1410) is injected into at least one stage of the pole teeth (1407, 1408) corresponding to the remaining pole shoes (1404, 1405).

2. The magnetic liquid sealing device with wide temperature applicability according to claim 1, characterized in that: The pole shoes (1403, 1404) have two stages.

3. The magnetic liquid sealing device with wide temperature applicability according to claim 1, characterized in that: The pole shoes (1403-1405) have three stages, and magnetic liquid A (1411) is injected into the pole teeth (1408) corresponding to the pole shoes (1405) adjacent to the open space.

4. The magnetic liquid sealing device with wide temperature applicability according to any one of claims 1 to 3, characterized in that: The number of teeth of each level of teeth (1406-1408) is different.

5. The magnetic liquid sealing device with wide temperature applicability according to claim 4, characterized in that: The end cover (122) is connected to the housing (12) via threads or bolts.

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