Large-shaft-diameter magnetic fluid sealing device for sealing atomized or gaseous medium

Abstract

The invention relates to the technical field of mechanical engineering sealing, in particular to a large-shaft-diameter magnetic fluid sealing device for sealing fog-state or gas-state media, and the large-shaft-diameter magnetic fluid sealing device comprises a movable pole shoe, a static pole shoe, a permanent magnet and a heat dissipation channel; the movable pole shoe is composed of a vertical part and a horizontal part which are integrally formed, annular labyrinth sealing convex teeth are arranged at the bottom end of the vertical part, and a plurality of sealing teeth are arranged on the lower surface of the horizontal part; the static pole shoe is located below the movable pole shoe, a labyrinth sealing groove is formed in the top of the static pole shoe, a buffer groove is formed in the outer side of the labyrinth sealing groove, a magnetofluid groove is formed in the outer side of the buffer groove, magnetofluid is arranged in the magnetofluid groove, the multiple sealing teeth are all inserted into the magnetofluid, a containing groove is formed in the bottom of the static pole shoe, and a permanent magnet is arranged in the containing groove; the heat dissipation channel is formed in the static pole shoe, and cooling liquid is arranged in the heat dissipation channel; the bearing capacity of the large-shaft-diameter magnetofluid seal can be enhanced, and meanwhile the stability and reliability of the magnetofluid seal are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical engineering sealing, and in particular to a large-diameter magnetic fluid sealing device for sealing mist or gaseous media. Background Art

[0002] In the field of large shaft diameter sealing such as coal gasification process gasifier, hydropower generation, etc., the space between the frame and the rotating shaft is filled with toxic and harmful polluting gases in mist and gaseous state during the operation of the equipment. The mist or gaseous medium is easy to diffuse to the outside from the gap between the frame and the rotating shaft, so it is necessary to seal the mist or gaseous medium between the frame and the rotating shaft; the existing seals have contact structures and non-contact structures. The contact structure is easy to wear and needs to be replaced and repaired regularly, and the operation and maintenance cost is extremely high, while the non-contact structure has problems such as poor sealing and easy leakage.

[0003] Magnetic fluid seals use magnetic fluid to form a liquid sealing layer when adsorbed to the gap between the pole shoe and the rotating shaft under an external magnetic field, forming a "liquid O-ring seal" with the characteristics of "zero leakage, low friction and self-recovery", which can achieve efficient sealing of gas or mist media. Existing magnetic fluid seals usually fix the static pole shoe on the frame, and directly fill the sealing gap formed by the rotating shaft and the pole shoe with magnetic fluid. This part of the magnetic fluid is adsorbed to the sealing gap by magnetic force under the action of the external magnetic field to play a sealing role.

[0004] However, the sealing pressure resistance of the existing magnetic fluid sealing structure is low. In particular, due to the characteristics of processing, manufacturing, installation and load conditions of large shaft diameter magnetic fluid seals, there is a large axial and radial gap between the rotating shaft and the frame. The sealing pressure resistance of the existing magnetic fluid seals at large shaft diameters is sharply reduced. Once the pressure of the mist or gas medium is high, the magnetic fluid film above it will be opened, causing the sealing structure to fail. At the same time, the linear speed of the sealing part corresponding to the large shaft diameter is usually high, and the friction heat generated by the magnetic fluid seal at high speed will also seriously weaken the magnetization performance of the magnetic fluid, further leading to the problem of reduced sealing pressure resistance of the magnetic fluid, making it impossible for the magnetic fluid to seal the mist or gas medium. Summary of the invention

[0005] In response to the above problems, the present invention provides a large-diameter magnetic fluid sealing device for sealing misty or gaseous media, which can stably and reliably achieve large-diameter magnetic fluid sealing, and the large sealing gap when the shaft diameter is large has no effect on the size of the sealing pressure resistance. At the same time, it can reduce the friction heat generated by the magnetic fluid seal when running at high speed, and avoid leakage of misty or gaseous media.

[0006] The technical solution of the present invention is: a large-diameter magnetic fluid sealing device for sealing a mist or gaseous medium is sleeved on the outside of a rotating shaft in a frame, and the gap between the rotating shaft and the frame is filled with a mist or gaseous medium. The large-diameter magnetic fluid sealing device comprises:

[0007] The movable pole shoe is composed of an integrally formed vertical portion and a horizontal portion, the cross section of the movable pole shoe is L-shaped as a whole, the top of the vertical portion is radially extended with an overlap portion, and the overlap portion is connected to the rotating shaft by bolts; the bottom end of the vertical portion is provided with an annular labyrinth sealing convex tooth, the outer side of the bottom end of the vertical portion is connected to the horizontal portion to form a whole, and the lower surface of the horizontal portion is provided with a plurality of annular sealing teeth, and there are gaps between the plurality of sealing teeth;

[0008] A static pole shoe is fixedly arranged on the frame, the static pole shoe is located below the dynamic pole shoe, and there is a gap between the upper surface of the static pole shoe and the lower surface of the dynamic pole shoe, a labyrinth sealing groove corresponding to the labyrinth sealing convex teeth is provided on the top of the static pole shoe, and there is a gap between the inner wall of the labyrinth sealing groove and the outer wall of the labyrinth sealing convex teeth; a buffer groove is provided on the outer side of the labyrinth sealing groove, a magnetic fluid groove is provided on the outer side of the buffer groove, a magnetic fluid is provided in the magnetic fluid groove, the magnetic fluid groove corresponds to the position of a plurality of sealing teeth, and a plurality of sealing teeth are inserted into the magnetic fluid, and there is a gap between the outer wall of the innermost sealing tooth and the outer wall of the outermost sealing tooth and the inner wall of the magnetic fluid groove; a placement groove is provided at the bottom of the static pole shoe, the placement groove corresponds to the position of the magnetic fluid groove, a permanent magnet is provided in the placement groove, and the permanent magnet is magnetized along the axial direction;

[0009] A heat dissipation channel is opened on the static pole shoe, a static pole shoe matching ring is provided above the heat dissipation channel, the static pole shoe matching ring is fixed to the static pole shoe by screws, and a rectangular heat dissipation channel circumferentially arranged on the static pole shoe is located on the outside of the magnetic fluid groove, coolant is provided in the heat dissipation channel, annular sealing grooves are provided on the inner and outer sides of the heat dissipation channel, and rubber sealing rings are provided in the two annular sealing grooves to prevent leakage of coolant.

[0010] Furthermore, a U-shaped magnetic fluid inlet channel is provided at the bottom of the magnetic fluid groove, a magnetic fluid inlet is provided through the static pole shoe matching ring, one end of the magnetic fluid inlet is connected to the magnetic fluid channel, and the other end of the magnetic fluid inlet is connected to the outside; a sealing groove is provided at the interface between the magnetic fluid inlet channel and the static pole shoe matching ring, and the sealing groove is provided on the static pole shoe, and a rubber sealing ring is provided in the sealing groove to prevent leakage of the magnetic fluid.

[0011] Furthermore, the liquid level of the magnetic fluid is 3 / 5 to 4 / 5 of the height of the inner wall of the magnetic fluid tank, the height of the inner wall of the magnetic fluid tank is lower than the height of its outer wall, and the magnetic fluid groove is connected to the external atmosphere.

[0012] Furthermore, the gap r1 between the small diameter of the innermost sealing tooth of the moving pole shoe along the radial direction and the small diameter of the magnetic fluid groove of the static pole shoe, the gap r2 between the large diameter of the outermost sealing tooth of the moving pole shoe along the radial direction and the large diameter of the magnetic fluid groove of the static pole shoe, the gap r3 between the small diameter of the labyrinth seal convex tooth on the moving pole shoe along the radial direction and the small diameter of the labyrinth seal groove on the static pole shoe, and the gap r4 between the large diameter of the labyrinth seal convex tooth on the moving pole shoe along the radial direction and the large diameter of the labyrinth seal groove on the static pole shoe, wherein r1, r2, r3 and r4 are all greater than the radial runout r1 of the rotating shaft when rotating. ; The top surface of the labyrinth seal groove on the static pole shoe and the upper plane on the outer side of the magnetic fluid groove of the static pole shoe are on the same horizontal plane, the gap h1 between the tooth top surface of the horizontal sealing tooth of the moving pole shoe and the bottom plane of the magnetic fluid groove, the gap h2 between the tooth top surface of the labyrinth seal convex tooth on the moving pole shoe and the bottom surface of the labyrinth seal groove of the static pole shoe, wherein h1 and h2 are both greater than the axial runout h of the moving pole shoe when the static pole shoe and the moving pole shoe rotate; such radial gaps r1, r2, r3, r4 and axial gaps h1, h2 ensure that there is no physical collision between the moving pole shoe and the static pole shoe during the operation of the rotating shaft.

[0013] Furthermore, the base liquid of the magnetic fluid is a fluorocarbon-based compound, and the moving pole shoe and the static pole shoe are both made of magnetic conductive materials.

[0014] Furthermore, the heat dissipation channel is connected to the outside through a coolant inlet and a coolant outlet, and the coolant inlet and the coolant outlet are both opened through the static pole shoe matching ring, and the coolant inlet and the coolant outlet are radially distributed at both ends of the diameter of the static pole shoe matching ring.

[0015] Furthermore, the cooling liquid cools the temperature of the magnetic fluid to 20°C to 80°C.

[0016] Beneficial effects of the present invention:

[0017] The magnetic fluid is gathered inside the magnetic fluid groove by its own gravity, and the sealing teeth on the moving pole shoe extend into the magnetic fluid to form a high-speed magnetic fluid sealing layer to play a sealing role. The magnetic field force of the permanent magnet is used to stably adsorb the magnetic fluid between the static pole shoe and the sealing teeth to enhance the sealing effect. The outer side of the magnetic fluid groove is connected to the external atmosphere, and the external atmosphere applies atmospheric pressure to the magnetic fluid in the magnetic fluid groove. The combined effects of magnetic force, gravity and atmospheric pressure work together to seal the mist or gaseous medium. The magnetic fluid sealing structure does not depend on the size of the radial gap and axial gap between the rotating shaft and the frame, and can achieve the pressure resistance performance of large-diameter magnetic fluid sealing, ensuring the stability and reliability of magnetic fluid sealing.

[0018] In addition, a labyrinth seal is formed by the cooperation between the labyrinth seal convex teeth on the moving pole shoe and the labyrinth seal groove on the static pole shoe, thereby increasing the flow path and resistance of the mist or gaseous medium, and utilizing the labyrinth seal to reduce the pressure of the mist or gaseous medium; the pressure of the mist or gaseous medium is reduced by the buffer groove opened on the static pole shoe, so that the pressure of the mist or gaseous medium before reaching the magnetic fluid sealing liquid surface is relatively stable, further enhancing the pressure-bearing capacity of the magnetic fluid.

[0019] When the linear speed of the pole shoe of a large diameter shaft is high, the heat of the magnetic fluid can be diffused in time through the circulation of coolant in the heat dissipation channel, thereby reducing the temperature of the magnetic fluid and ensuring the stability and reliability of the magnetic fluid seal. This avoids the heat generated by the high-speed friction between the sealing teeth and the magnetic fluid, which causes the temperature of the magnetic fluid to rise, thereby reducing the stability of the magnetic fluid or even causing it to fail. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 It is a schematic cutaway diagram of the front view of the present invention;

[0022] Figure 2 for Figure 1 A partial enlarged view of the middle A;

[0023] Figure 3 for Figure 1 A partial enlarged view of point B in the middle;

[0024] Figure 4 for Figure 1 A partial enlarged view of point C in the middle;

[0025] Figure 5 It is a schematic diagram of the existing magnetic fluid shaft sealing structure;

[0026] Figure 6 It is a schematic diagram of the existing magnetic fluid shaft end face sealing structure. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "one side", "one end", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the 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 cannot be understood as a limitation on the present invention; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Since large-diameter magnetic fluid seals have low pressure resistance, once the pressure of the mist or gas medium is high, the magnetic fluid above it will be broken, causing the seal to fail. In addition, the friction heat generated by the magnetic fluid seal under high-speed conditions will also seriously weaken the magnetization performance of the magnetic fluid. In view of this, the inventors of the present application provide a large-diameter magnetic fluid seal device for sealing mist or gaseous media, which can enhance the pressure-bearing capacity of the magnetic fluid and ensure the stability and reliability of the magnetic fluid seal under high-speed conditions.

[0030] like Figure 1-4 As shown, a large-diameter magnetic fluid sealing device for sealing mist or gaseous media is sleeved on the outside of a rotating shaft 2 in a frame 1, and a gap between the rotating shaft 2 and the frame 1 is filled with a mist or gaseous medium 6. The large-diameter magnetic fluid sealing device includes: a moving pole shoe 3, a static pole shoe 4 and a heat dissipation channel 5.

[0031] Among them, the moving pole shoe 3 is composed of an integrally formed vertical portion 31 and a horizontal portion 32. The cross-section of the moving pole shoe 3 is L-shaped as a whole. A lap portion 33 radially extends from the top of the vertical portion 31, and the lap portion 33 is connected to the rotating shaft 2 by bolts; an annular labyrinth sealing convex tooth 34 is provided at the bottom end of the vertical portion 31, and the outer side of the bottom end of the vertical portion 31 is connected to the horizontal portion 32 to form a whole, and a plurality of annular sealing teeth 35 are provided on the lower surface of the horizontal portion 32.

[0032] Based on the above embodiment, the overlapping portion 33 of the moving pole shoe 3 is connected to the rotating shaft 2 by bolts, and when the rotating shaft 2 rotates, the moving pole shoe 3 is driven to rotate.

[0033] In this embodiment, if Figure 1-3As shown, the static pole shoe 4 is fixedly arranged on the frame 1, the static pole shoe 4 is located below the dynamic pole shoe 3, and there is a gap between the upper surface of the static pole shoe 4 and the lower surface of the dynamic pole shoe 3, the top of the static pole shoe 4 is provided with a labyrinth seal groove 41 corresponding to the labyrinth seal convex teeth 34, and there are gaps r3 and r4 between the inner wall of the labyrinth seal groove 41 and the outer wall of the labyrinth seal convex teeth 34; a buffer groove 42 is provided on the outer side of the labyrinth seal groove 41, and a magnetic fluid groove 43 is provided on the outer side of the buffer groove 42, and the magnetic fluid groove 4 3 is provided with a magnetic fluid 7, the magnetic fluid groove 43 corresponds to the position of the plurality of sealing teeth 35, and the plurality of sealing teeth 35 are all inserted into the magnetic fluid 7, there is a gap r1 between the outer wall of the innermost sealing tooth 35 and the inner wall of the magnetic fluid groove 43, and there is a gap r2 between the outermost sealing tooth 35 and the inner wall of the magnetic fluid groove 43; a placement groove is provided at the bottom of the static pole shoe 4, the placement groove corresponds to the position of the magnetic fluid groove 43, a permanent magnet 8 is arranged in the placement groove, and the permanent magnet 8 is magnetized along the axial direction.

[0034] Based on the above embodiment, the labyrinth seal convex teeth 34 penetrate into the interior of the labyrinth seal groove 41, and when the rotating shaft 2 drives the moving pole shoe 3 to rotate, the labyrinth seal convex teeth 34 rotate in the labyrinth seal groove 41; there are gaps between the multiple sealing teeth 35, and the magnetic fluid groove 43 and the multiple sealing teeth 35 are all arranged in an annular shape; when the moving pole shoe 3 rotates, it can drive the multiple sealing teeth 35 at its bottom to rotate smoothly in the magnetic fluid groove 43 without causing splashing of the magnetic fluid 7; a buffer groove 42 is opened on the static pole shoe 4 to reduce the pressure of the mist or gaseous medium, so that the pressure of the mist or gaseous medium 6 before reaching the liquid surface of the magnetic fluid 7 is relatively stable; the sealing teeth 35 on the moving pole shoe 3 extend into the magnetic fluid 7 to form a dynamic strong magnetic fluid sealing layer, the number of sealing teeth 35 is determined according to the actual working conditions, and the tooth width and length of the sealing teeth 35 are determined according to specific usage requirements.

[0035] In this embodiment, if Figure 1 , Figure 4 As shown, the heat dissipation channel 5 is opened on the static pole shoe 4, and a static pole shoe matching ring 9 is arranged above the heat dissipation channel 5. The static pole shoe matching ring 9 is fixed to the static pole shoe 4 by screws, and the rectangular heat dissipation channel 5 circumferentially arranged on the static pole shoe 4 is located on the outside of the magnetic fluid groove 43, and coolant is arranged in the heat dissipation channel 5. Annular sealing grooves 45 are opened on the inner and outer sides of the heat dissipation channel 5, and rubber sealing rings 10 are arranged in the two annular sealing grooves 45 to prevent leakage of coolant.

[0036] Based on the above embodiment, the magnetic fluid 7 is cooled by the heat dissipation channel 5 arranged in an annular manner on the outer side of the magnetic fluid groove 43, so as to avoid the temperature of the magnetic fluid 7 being increased due to the heat generated by the high-speed friction between the sealing teeth 35 and the magnetic fluid 7, which may cause the stability of the magnetic fluid 7 to decrease or even fail. According to the actual working conditions and specific use requirements, the cooling power is changed by changing the depth and width of the heat dissipation channel 5, the circulation speed of the coolant and the coolant medium, so as to make the magnetic fluid seal more efficient and reliable.

[0037] In this embodiment, a U-shaped magnetic fluid inlet channel 47 is provided at the bottom of the magnetic fluid groove 43, a magnetic fluid inlet 44 is provided through the static pole shoe matching ring 9, and one end of the magnetic fluid inlet 44 is connected to the magnetic fluid channel 47, and the other end of the magnetic fluid inlet 44 is connected to the outside; a sealing groove is provided at the interface between the magnetic fluid inlet channel 47 and the static pole shoe matching ring 9, that is, a sealing groove 46 is provided at one end of the magnetic fluid inlet channel 47 connected to the magnetic fluid inlet 44, and the sealing groove 46 is provided on the static pole shoe 4, and a rubber sealing ring 11 is provided in the sealing groove 46 to prevent leakage of the magnetic fluid, and the magnetic fluid 7 is replenished or reduced into the magnetic fluid groove 43 through the magnetic fluid inlet 44.

[0038] In this embodiment, if Figure 1 , Figure 3 As shown, the liquid level of the magnetic fluid 7 is 3 / 5 to 4 / 5 of the height of the inner wall of the magnetic fluid groove 43, the height of the inner wall of the magnetic fluid groove 43 is lower than the height of its outer wall, and the magnetic fluid groove 43 is connected to the external atmosphere.

[0039] Based on the above embodiments, in the rotating mechanical seal, the liquid level of the magnetic fluid 7 needs to ensure that the magnetic fluid 7 is evenly distributed in the magnetic field to achieve the expected sealing, shock absorption or heat dissipation effect, but it should not be too high to avoid unnecessary waste. At the same time, a too high liquid level of the magnetic fluid 7 may cause unstable flow, and a too low liquid level of the magnetic fluid 7 may not achieve the expected effect. Generally, the liquid level range of the magnetic fluid 7 will be designed to be between 60% and 80% of the depth of the magnetic fluid groove 43, but the specific value needs to be adjusted according to the specific application. Since the height of the outer wall of the magnetic fluid groove 43 is higher than its inner wall, the magnetic fluid 7 in the magnetic fluid groove 43 is prevented from flowing out of the static pole shoe 4. At the same time, since the magnetic fluid groove 43 is connected to the external atmosphere, the magnetic fluid 7 is gathered in the magnetic fluid groove 43 under the action of atmospheric pressure, gravity and magnetic field force.

[0040] In this embodiment, the base liquid of the magnetic fluid 7 is a fluorocarbon-based compound, and the moving pole piece 3 and the static pole piece 4 are both made of magnetic conductive materials.

[0041] Based on the above embodiments, the fluorocarbon-based compound is used as the base liquid of the magnetic fluid 7, so that the magnetic fluid 7 has the characteristics of being non-flammable, having a wide temperature range, and being insoluble in other liquids, thereby making the magnetic fluid 7 suitable for use in active environments.

[0042] In this embodiment, if Figure 1 , Figure 4 As shown, the heat dissipation channel 5 is connected to the outside through the coolant inlet 51 and the coolant outlet 52. The coolant inlet 51 and the coolant outlet 52 are both opened through the upper part of the static pole shoe matching ring 9, and the coolant inlet 51 and the coolant outlet 52 are radially distributed at both ends of the diameter of the static pole shoe matching ring 9.

[0043] Based on the above embodiment, coolant is input into the heat dissipation channel 5 through the coolant inlet 51, the coolant in the heat dissipation channel 5 flows to the other end of its diameter, and the coolant after heat exchange is discharged through the coolant outlet 52. At this time, the coolant ring is arranged on the outside of the magnetic fluid groove 43; the coolant inlet 51 and the coolant outlet 52 are distributed along the two ends of the diameter of the rotating shaft 2 to ensure the cooling effect of the coolant on the magnetic fluid 7.

[0044] In this embodiment, the cooling liquid cools the temperature of the magnetic fluid 7 to 20°C to 80°C.

[0045] Based on the above embodiments, under normal circumstances, the temperature range of the magnetic fluid 7 is between -20°C and 105°C. Too high or too low temperatures will cause the magnetic properties of the magnetic fluid to decrease significantly; the optimal sealing temperature of the magnetic fluid 7 depends on the specific application and material properties; usually the operating temperature range of the magnetic fluid 7 is between 0°C and 100°C. Higher temperatures may cause the magnetic fluid 7 to evaporate or the viscosity to change, and lower temperatures may affect the fluidity and stability of the magnetic fluid 7.

[0046] In this embodiment, the gap r1 between the small diameter of the radially innermost sealing tooth 35 of the moving pole shoe 3 and the small diameter of the magnetic fluid groove 43 of the static pole shoe, the gap r2 between the large diameter of the radially outermost sealing tooth 35 of the moving pole shoe 3 and the large diameter of the magnetic fluid groove 43 of the static pole shoe, the gap r3 between the radial small diameter of the labyrinth seal convex tooth 34 on the moving pole shoe 2 and the small diameter of the labyrinth seal groove 41 on the static pole shoe 4, and the gap r4 between the radial large diameter of the labyrinth seal convex tooth 34 on the moving pole shoe 3 and the large diameter of the labyrinth seal groove 41 on the static pole shoe 4; wherein r1, r2, r3 and r4 are all greater than the radial runout r of the rotating shaft 2 when rotating; Figure 5As shown, in the existing magnetic fluid shaft sealing structure, the radial sealing gap must be greater than or equal to r, that is, the sealing gap mr=r+Δr, because the larger the radial sealing gap increment Δr, the smaller the sealing pressure resistance, therefore, Δr is required to be as small as possible. However, the sealing structure in the present invention does not rely on the sealing gap mr=r+Δr between the rotating shaft 2 and the static pole shoe 4, wherein Δr can be much larger than the radial runout r. As long as the sealing gap mr meets the structural strength and rigidity requirements, the sealing gap has no effect on the sealing pressure resistance. Therefore, the pressure resistance of the sealing structure of the present invention has nothing to do with the sealing gap. The top surface of the labyrinth sealing groove 41 on the static pole shoe 4 and the outer upper plane of the magnetic fluid groove 43 on the static pole shoe 4 are on the same horizontal plane, and the gap h1 between the tooth top surface of the horizontal sealing tooth 35 of the moving pole shoe and the plane of the magnetic fluid groove 43, and the gap h2 between the tooth top surface of the labyrinth sealing convex tooth 34 on the moving pole shoe 3 and the bottom surface of the labyrinth sealing groove 41 on the static pole shoe 4, wherein h1, h2 and h3 are all larger than the axial runout h of the moving pole shoe 2 when the static pole shoe 4 and the moving pole shoe 3 rotate relative to each other. Figure 6 As shown, in the existing magnetic fluid shaft end face sealing structure, the axial clearance needs to be greater than or equal to h, that is, the axial clearance mh=h+Δh, because the larger the axial clearance increment Δh is, the smaller the sealing pressure resistance is. Therefore, Δh is required to be as small as possible. However, the sealing structure in the present invention does not rely on the axial clearance mh=h+Δh between the moving pole shoe 3 and the static pole shoe 4, wherein Δh can be much larger than the axial runout h, at least 2 to 3 times of the axial runout h. As long as the axial clearance mh meets the structural strength and stiffness requirements, the axial clearance has no effect on the sealing pressure resistance. Therefore, the pressure resistance of the sealing structure of the present invention is independent of the axial clearance. Such radial and axial clearances ensure that the shaft 2 will not collide with the static pole shoe during operation, and at the same time, when the shaft 2 drives the moving pole shoe 3 to rotate, physical collision between the moving pole shoe 3 and the static pole shoe 4 is avoided.

[0047] The sealing pressure resistance of the magnetic fluid sealing structure does not depend on the size of the radial gap between the rotating shaft 2 and the static pole shoe 4 , and also does not depend on the size of the axial gap between the moving pole shoe 3 and the static pole shoe 4 .

[0048] Based on the above embodiment, the labyrinth seal groove 41 and the labyrinth seal protruding teeth 34 form a labyrinth seal. The structure of the labyrinth seal is determined according to the actual working conditions and specific use requirements. Specifically, a straight-through type, a staggered type or a stepped type can be selected.

[0049] The working principle of the present invention is as follows: the static pole shoe 4 is fixedly mounted on the frame 1, the overlapping portion 33 of the dynamic pole shoe 3 is fixed to the rotating shaft 2 by a number of evenly distributed bolts, the rotating shaft 2 is started, and the dynamic pole shoe 3 rotates together with the rotating shaft 2; the labyrinth seal convex teeth 34 on the dynamic pole shoe 3 cooperate with the labyrinth seal groove 41 on the static pole shoe 4 to form a labyrinth seal, and the mist or gaseous medium 6 enters the labyrinth seal through the sealing gap to increase the flow path and resistance of the mist or gaseous medium 6, and the labyrinth seal is used to reduce the pressure of the mist or gaseous medium 6; a buffer groove 42 is provided on the static pole shoe 4 to reduce the pressure of the mist or gaseous medium 6, so that the pressure of the mist or gaseous medium 6 before reaching the sealing liquid surface of the magnetic fluid 7 is relatively stable; the sealing teeth 35 on the dynamic pole shoe 3 extend into the magnetic fluid 7 to form a high-speed magnetic fluid sealing layer, and the magnetic fluid 7 relies on its own gravity to gather inside the magnetic fluid groove 43. In addition, the permanent magnet 8 is installed in the placement groove at the bottom of the static pole shoe 4, and the permanent magnet 8 is magnetized along the axial direction. The magnetic force of the permanent magnet 8 produces an adsorption effect on the magnetic fluid 7 between the sealing tooth and the bottom surface of the magnetic fluid groove, thereby enhancing the sealing ability. The outer side of the magnetic fluid groove 43 is connected to the external atmosphere, and the external atmosphere applies atmospheric pressure to the magnetic fluid 7 in the magnetic fluid groove 43. The magnetic fluid 4 has a sealing effect on the mist or gaseous medium 6 under the combined action of magnetic force, gravity and atmospheric pressure.

[0050] A heat dissipation channel 5 is provided on the static pole shoe 4, and the heat dissipation channel ring 5 is provided on the outside of the magnetic fluid 7. A static pole shoe matching ring 9 is provided on the heat dissipation channel 5, and a coolant inlet 51 and a coolant outlet 52 are provided on the static pole shoe matching ring 9. When the rotating shaft 2 rotates and thus drives the moving pole shoe 3 to rotate at a high speed, the heat is diffused in time through the circulation of the coolant in the heat dissipation channel 5, thereby reducing the temperature of the magnetic fluid 7 and ensuring the stability and reliability of the magnetic fluid seal, thereby avoiding the heat generated by the high-speed friction between the sealing teeth 35 and the magnetic fluid 7 causing the temperature of the magnetic fluid 7 to rise, thereby causing the stability of the magnetic fluid 7 to decrease or even fail.

[0051] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-diameter magnetic fluid sealing device for sealing mist or gaseous medium, which is sleeved on the outside of the rotating shaft in the frame, and the gap between the rotating shaft and the frame is filled with mist or gaseous medium, characterized in that: The large shaft diameter magnetic fluid sealing device includes: The movable pole shoe is composed of an integrally formed vertical portion and a horizontal portion, the cross section of the movable pole shoe is L-shaped as a whole, the top of the vertical portion is radially extended with an overlap portion, and the overlap portion is fixedly connected to the rotating shaft; the bottom end of the vertical portion is provided with an annular labyrinth sealing convex tooth, the outer side of the bottom end of the vertical portion is connected to the horizontal portion to form a whole, and the lower surface of the horizontal portion is provided with a plurality of annular sealing teeth, and there are gaps between the plurality of sealing teeth; A static pole shoe is fixedly arranged on the frame, the static pole shoe is located below the dynamic pole shoe, and there is a gap between the upper surface of the static pole shoe and the lower surface of the dynamic pole shoe, a labyrinth sealing groove corresponding to the labyrinth sealing convex teeth is provided on the top of the static pole shoe, and there is a gap between the inner wall of the labyrinth sealing groove and the outer wall of the labyrinth sealing convex teeth; a buffer groove is provided on the outer side of the labyrinth sealing groove, a magnetic fluid groove is provided on the outer side of the buffer groove, a magnetic fluid is provided in the magnetic fluid groove, the magnetic fluid groove corresponds to the position of a plurality of sealing teeth, and a plurality of sealing teeth are inserted into the magnetic fluid, and there is a gap between the outer wall of the innermost sealing tooth and the outer wall of the outermost sealing tooth and the inner wall of the magnetic fluid groove; a placement groove is provided at the bottom of the static pole shoe, the placement groove corresponds to the position of the magnetic fluid groove, a permanent magnet is provided in the placement groove, and the permanent magnet is magnetized along the axial direction; A heat dissipation channel is opened on the static pole shoe, a static pole shoe matching ring is provided above the heat dissipation channel, the static pole shoe matching ring is fixed on the static pole shoe, and the rectangular heat dissipation channel circumferentially arranged on the static pole shoe is located on the outside of the magnetic fluid groove, and coolant is arranged in the heat dissipation channel, annular sealing grooves are opened on the inner and outer sides of the heat dissipation channel, and rubber sealing rings are provided in the two annular sealing grooves to prevent leakage of coolant.

2. The large-diameter magnetic fluid sealing device for sealing mist or gaseous media according to claim 1, characterized in that: A U-shaped magnetic fluid inlet channel is provided at the bottom of the magnetic fluid groove, a magnetic fluid inlet is provided through the static pole shoe matching ring, one end of the magnetic fluid inlet is connected with the magnetic fluid channel, and the other end of the magnetic fluid inlet is connected with the outside; a sealing groove is provided at the interface between the magnetic fluid inlet channel and the static pole shoe matching ring, and the sealing groove is provided on the static pole shoe, and a rubber sealing ring is provided in the sealing groove to prevent leakage of the magnetic fluid.

3. The large-diameter magnetic fluid sealing device for sealing mist or gaseous media according to claim 2, characterized in that: The liquid level of the magnetic fluid is 3 / 5 to 4 / 5 of the height of the inner wall of the magnetic fluid tank. The height of the inner wall of the magnetic fluid tank is lower than the height of its outer wall. The magnetic fluid groove is connected to the external atmosphere.

4. The large-diameter magnetic fluid sealing device for sealing mist or gaseous media according to any one of claims 1 to 3, characterized in that: The gap r1 between the small diameter of the innermost sealing tooth of the moving pole shoe along the radial direction and the small diameter of the magnetic fluid groove of the static pole shoe, the gap r2 between the large diameter of the outermost sealing tooth of the moving pole shoe along the radial direction and the large diameter of the magnetic fluid groove of the static pole shoe, the gap r3 between the small diameter of the labyrinth seal convex tooth on the moving pole shoe along the radial direction and the small diameter of the labyrinth seal groove on the static pole shoe, and the gap r4 between the large diameter of the labyrinth seal convex tooth on the moving pole shoe along the radial direction and the large diameter of the labyrinth seal groove on the static pole shoe, wherein r1, r2, r3 and r4 are all greater than the radial runout r of the rotating shaft when rotating. ; The top surface of the labyrinth seal groove on the static pole shoe and the upper plane on the outer side of the magnetic fluid groove of the static pole shoe are on the same horizontal plane, the gap h1 between the tooth top surface of the horizontal sealing tooth of the moving pole shoe and the bottom plane of the magnetic fluid groove, the gap h2 between the tooth top surface of the labyrinth seal convex tooth on the moving pole shoe and the bottom surface of the labyrinth seal groove of the static pole shoe, wherein h1 and h2 are both greater than the axial runout h of the moving pole shoe when the static pole shoe and the moving pole shoe rotate; such radial gaps r1, r2, r3, r4 and axial gaps h1, h2 avoid physical collision between the moving pole shoe and the static pole shoe during the operation of the rotating shaft.

5. The large-diameter magnetic fluid sealing device for sealing mist or gaseous media according to claim 3, characterized in that: The base liquid of the magnetic fluid is a fluorocarbon-based compound, and the moving pole shoe and the static pole shoe are both made of magnetic conductive materials.

6. The large-diameter magnetic fluid sealing device for sealing mist or gaseous media according to claim 5, characterized in that: The heat dissipation channel is connected to the outside through a coolant inlet and a coolant outlet. The coolant inlet and the coolant outlet are both opened through the static pole shoe matching ring, and the coolant inlet and the coolant outlet are radially distributed at both ends of the diameter of the static pole shoe matching ring.

7. The large-diameter magnetic fluid sealing device for sealing mist or gaseous media according to claim 6, characterized in that: The cooling liquid cools the temperature of the magnetic fluid to 20°C to 80°C.

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