Ultralow-temperature self-heating type magnetofluid sealing device

Abstract

The invention relates to an ultralow-temperature self-heating type magnetofluid sealing device, and belongs to the technical field of magnetofluid sealing, the ultralow-temperature self-heating type magnetofluid sealing device comprises a mechanical seal, a magnetofluid seal and a bearing which are sequentially arranged from a medium side to an atmosphere side in the axial direction, the mechanical seal comprises a moving ring and a bearing seat, the moving ring and a shaft sleeve synchronously rotate, and the bearing seat is fixed to an equipment shell; the medium side end face of the bearing seat can be directly used as a static ring end face of mechanical sealing, so that the moving ring is connected to the medium side end face of the bearing seat in a pressing mode to form end face sealing. The magnetic fluid seal comprises a pole shoe installed in the bearing seat and a plurality of magnetic columns arranged in an outer side groove of the pole shoe, gaps used for being filled with magnetic liquid can be formed between the pole shoe and the shaft sleeve, and the magnetic liquid filled in the gaps is restrained by a magnetic field formed by the magnetic columns to form a plurality of liquid O-shaped rings.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic fluid sealing, and in particular to an ultra-low temperature self-heating magnetic fluid sealing device. Background Art

[0002] Magnetic fluid seals mainly rely on the strong magnetic field generated by permanent magnets to tightly adsorb magnetic fluid in the gap between the sealing teeth (pole shoes) to form a liquid O-ring, thereby sealing the medium. Magnetic fluid seals have the advantages of extremely low leakage rate, low mechanical energy consumption, and long service life.

[0003] like Fig.21 As shown, in order to prevent the medium in the medium chamber from leaking into the atmospheric chamber, pole shoes, permanent magnets, magnetic liquid, sealing sleeves, sealing shells, auxiliary sealing rings and other parts are arranged between the medium chamber and the atmospheric chamber, wherein the sealing sleeves and auxiliary sealing rings can rotate with the device shaft, and the remaining parts are fixed together with the device shell and relatively stationary with the sealing sleeves. Therefore, there is relative rotation between the pole shoes and the sleeves, and a gap is designed between the two parts. In order to prevent the medium from leaking into the atmospheric chamber along this gap, "magnetic liquid" (referred to as magnetic liquid) can be injected into this gap. Under the action of the magnetic field, the magnetic liquid is adsorbed in the middle of the gap between the pole shoes and the sleeves and fills the gap between the pole shoes and the sleeves, thereby forming multiple "liquid O-rings" between the pole shoes and the sleeves to achieve sealing of the medium.

[0004] CN108374895A discloses a low-temperature resistant compact magnetic fluid sealing device, which includes a boss-shaped disc and a thin disc-shaped rotating shaft. The disc and the rotating shaft are coaxially arranged and aligned at both ends. A bearing and an annular magnetic fluid sealing structure with a sealing function are arranged between the rotating shaft and the disc. The magnetic fluid sealing structure includes a magnetic fluid and a magnetic pole. A heater for heating the magnetic fluid is provided on the magnetic fluid sealing structure.

[0005] CN212080163U discloses a low temperature resistant magnetic fluid sealing device, comprising a housing, a magnetic fluid sealing mechanism and a transmission shaft, wherein a main cavity is provided in the housing, the transmission shaft is rotatably mounted in the main cavity, a magnetic fluid sealing mechanism is provided between the housing and the transmission shaft, bearings are provided on both sides of the magnetic fluid sealing mechanism, the housing is provided with a heat preservation cavity, a heater is provided on the side wall of the heat preservation cavity, and the heat preservation cavity is filled with heat transfer oil. The heater heats and heats the magnetic fluid sealing mechanism on the inner side of the housing by heating the heat transfer oil in the heat preservation cavity, thereby preventing the low temperature environment from affecting the normal operation of the magnetic fluid sealing mechanism. The heat transfer oil has a high specific heat capacity, heat transfer efficiency and thermal stability, and reduces the fluctuation of the working temperature. At the same time, the working temperature of the heat transfer oil is between -80 and 330 degrees, which can well cover the working temperature range of the magnetic fluid sealing mechanism.

[0006] When the magnetic fluid seal is assembled, the magnetic fluid is adsorbed in the gap between the pole shoe and the sleeve under the action of the magnetic field, forming a Fig. 22 Multiple liquid O-rings and chambers are shown. When the medium chamber on the left is filled with high-pressure medium, the high-pressure medium will leak to the atmosphere on the right, and due to the effect of the magnetic field, each liquid O-ring will form a certain resistance to the medium. Liquid O-ring sealing is essentially a step-by-step pressure reduction process, and the healing ability of the liquid O-ring itself is the key to whether it can achieve step-by-step pressure reduction. The fluidity of the magnetic fluid ensures that it can flow quickly with the magnetic field, so the viscosity of the magnetic fluid is an important indicator. To ensure the fluidity of the magnetic fluid, the viscosity of the magnetic fluid is recommended to be less than 2000cp.

[0007] When magnetic fluid seals are used in low-temperature environments, the viscosity of the magnetic liquid will increase rapidly at low temperatures, causing the magnetic liquid to have no fluidity and unable to be evenly dispersed in the gap between the pole shoe and the sleeve, resulting in the inability to seal. The reason for this problem is that the magnetic fluid usually contains three raw materials: magnetic nanoparticles, base liquid, and active dispersant. The base liquid and active dispersant are both liquids, generally water, engine oil, glycerin, kerosene, etc. When the temperature of these liquids is below -40°C, their viscosity will rise rapidly to more than 5000cp, or even become solid. At this time, a liquid O-ring cannot be formed between the pole shoe and the sleeve, resulting in the inability of the magnetic fluid seal to seal. Therefore, the development of a new magnetic fluid sealing device that can autonomously maintain the working temperature of the magnetic fluid and adapt to ultra-low temperature environments has become a technical bottleneck that needs to be broken through in this field.

[0008] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the invention

[0009] In view of the deficiencies of the prior art, the present invention aims to provide an ultra-low temperature self-heating magnetic fluid sealing device, which can increase the temperature of the magnetic fluid seal through the heat generated during the operation of the mechanical seal, and accelerate the heat exchange between the sealing device and the atmospheric environment through a heat exchange chamber, so that the temperature of the magnetic fluid seal is further increased, and finally the sealing device can be used in a working environment below -100°C, thereby solving the problem that the magnetic fluid seal cannot be used below -40°C due to the viscosity limitation of the magnetic liquid at low temperatures.

[0010] The invention discloses an ultra-low temperature self-heating magnetic fluid sealing device, which comprises: a mechanical seal, a magnetic fluid seal and a bearing which are arranged in sequence along the axial direction from the medium side to the atmosphere side, wherein the mechanical seal comprises a moving ring which rotates synchronously with a shaft sleeve and a bearing seat which is fixed to a device housing, and the medium side end face of the bearing seat can directly serve as the static ring end face of the mechanical seal, so that the moving ring is pressed against the medium side end face of the bearing seat to form an end face seal; the magnetic fluid seal comprises a pole shoe installed in the bearing seat and a plurality of magnetic columns arranged in a groove outside the pole shoe, and a gap for filling a magnetic liquid can be formed between the pole shoe and the shaft sleeve, and the magnetic liquid filled in these gaps forms a plurality of liquid O-rings after being constrained by a magnetic field formed by the magnetic columns.

[0011] According to a preferred embodiment, the dynamic ring is integrated with the head seat through a shrink sleeve, the head seat is connected to one end of the bellows, and the other end of the bellows is connected to the spring seat to assemble into a bellows assembly, wherein the medium side end face of the spring seat is in contact with the compression sleeve end face of the compression sleeve close to the atmosphere side.

[0012] According to a preferred embodiment, a plurality of cylindrical head screws are arranged circumferentially between the clamping sleeve and the sleeve, and a first gap is also provided so that when the cylindrical head screws are tightened, the sleeve end face close to the medium side and the clamping sleeve concave surface in the groove of the clamping sleeve do not contact, but the clamping sleeve end face contacts the spring seat first.

[0013] According to a preferred embodiment, a first wedge-shaped pad is provided between the sleeve, the rotating shaft and the clamping sleeve, and a second wedge-shaped pad is provided between the spring seat, the sleeve and the collecting sleeve, and contact surfaces of the first wedge-shaped pad and the second wedge-shaped pad form a first inclined surface and a second inclined surface respectively, wherein the first inclined surface contacts the sleeve, and the second inclined surface contacts the collecting sleeve.

[0014] According to a preferred embodiment, a protrusion extending axially toward the atmosphere side is provided on the collecting sleeve, and a protrusion extending axially toward the medium side is provided on the pole shoe, and the two protrusions are staggered to form a first chamber; a protrusion extending axially toward the atmosphere side is provided on the pole shoe, and a protrusion extending axially toward the medium side is provided on the sleeve, and the two protrusions are staggered to form a second chamber, wherein the first chamber and the second chamber can store magnetic liquid.

[0015] According to a preferred embodiment, the magnetic field formed by the magnetic column can form a magnetic field loop between the pole shoe and the sleeve. Under the action of the magnetic field loop, the magnetic liquid can be adsorbed in the gap between the pole shoe and the sleeve, thereby forming a liquid O-ring arranged in a full circle along the circumferential direction at each tooth tip of the pole shoe.

[0016] According to a preferred embodiment, the bearing comprises a first bearing and a second bearing installed in a bearing seat, a second spacer sleeve is arranged between the two for increasing the span between the two bearings, and a first spacer sleeve is arranged between the first bearing and the pole shoe for pressing and positioning the pole shoe.

[0017] According to a preferred embodiment, the moving ring is connected to the sleeve via a first set screw, a step is provided on the sleeve for positioning the first bearing, and the atmospheric end of the sleeve positions the second bearing via a shaft elastic retaining ring.

[0018] According to a preferred embodiment, a plurality of sleeve upper notches are arranged on the pressing sleeve for pressing the second bearing outer ring, and a first sleeve notch corresponding to the sleeve upper notch and a second sleeve notch surrounded by the first sleeve notch are arranged on the sleeve.

[0019] According to a preferred embodiment, the gas in the heat exchange chamber formed between the sleeve and the rotating shaft can be cooled down after heat exchange with the sleeve and the rotating shaft to form a second gas. When the driving ring rotates, the first gas in the outer atmospheric environment enters the heat exchange chamber through the notch on the pressing sleeve and the notch on the first sleeve after compression to exchange with the second gas, and part of the second gas is taken out from the notch on the second sleeve.

[0020] The beneficial technical effects of the present invention are:

[0021] First, the present invention reasonably combines mechanical seals with magnetic fluid seals, so that the equipment can still maintain good sealing performance in low-temperature environments. The mechanical seal can not only initially block a large amount of low-temperature media from directly contacting the magnetic fluid seal, but also use the heat generated during operation to increase the working temperature of the magnetic fluid seal, ensuring that it can work effectively in an environment below -100°C. This combined structural design cleverly solves the problem that traditional magnetic fluid seals lose fluidity and sealing ability at extremely low temperatures due to the increase in magnetic fluid viscosity.

[0022] Secondly, the present invention adopts the design of directly using the bearing seat as the static ring of the mechanical seal, which reduces the leakage points and shortens the heat transfer path, speeding up the speed of heat transfer from the mechanical seal to the magnetic fluid seal, thereby improving the temperature adaptability of the overall sealing device. At the same time, the design of the wedge-shaped sealing gasket at the inner hole of the sleeve and the spring seat position ensures effective radial and axial sealing at the same time under low temperature conditions, further enhancing the reliability and stability of the sealing system.

[0023] In addition, by designing heat exchange and insulation chambers in the shaft sleeve and the sealing chamber and connecting them to the atmosphere, the direct contact area between the sealing components and the cryogenic medium is reduced, and the heat exchange efficiency between the core part of the magnetic fluid seal and the external environment is increased. This not only helps to increase the operating temperature of the sealing part, but also reduces the impact of the cryogenic medium on the sealing system, ensuring that the sealing device can operate stably under extreme low temperature conditions.

[0024] Finally, the designed magnetic fluid collection device (i.e., the first chamber and the second chamber) can collect part of the leaked magnetic fluid when low temperature causes the viscosity of the magnetic fluid to increase and the fluidity to deteriorate, and re-absorb it back into the gap between the pole shoe and the sleeve after the temperature rises, thereby ensuring the durability and reliability of the sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the exploded structure of the sealing device provided by the present invention;

[0026] Figure 2 is a cross-sectional view of the sealing device provided by the present invention;

[0027] Figure 3 It is a schematic diagram of the mechanical seal structure in the sealing device provided by the present invention;

[0028] Figure 4 It is a structural schematic diagram of the bellows assembly provided by the present invention;

[0029] Figure 5 is a schematic diagram of a wedge-shaped pad compression implementation scheme provided by the present invention, wherein only parts related to the wedge-shaped pad are shown;

[0030] Figure 6 is a schematic diagram of the sealing direction of the second wedge-shaped pad provided by the present invention, wherein only parts related to the second wedge-shaped pad are shown;

[0031] Figure 7 is a schematic diagram of the sealing direction of the first wedge-shaped pad provided by the present invention, wherein only parts related to the first wedge-shaped pad are shown;

[0032] Figure 8 Schematic diagram of the seal between the bearing seat and the equipment housing provided by the present invention, wherein only relevant parts are shown;

[0033] Fig. 9 It is a structural schematic diagram of the magnetic liquid collecting device on the medium side provided by the present invention;

[0034] Fig.10 It is a structural schematic diagram of the magnetic liquid collecting device on the atmosphere side provided by the present invention;

[0035] Fig.11 It is a schematic diagram of the assembly of the sealing device, the equipment housing and the rotating shaft provided by the present invention;

[0036] Fig.12 It is a schematic diagram of mechanical seal stress and leakage of the sealing device provided by the present invention;

[0037] Fig.13 It is a schematic diagram of the structure of the independent static ring provided by the present invention;

[0038] Fig.14 is a schematic diagram of a magnetic field loop provided by the present invention;

[0039] Fig.15 It is a schematic diagram of the structure of the magnetic fluid O-ring provided by the present invention;

[0040] Fig.16 It is a schematic structural diagram of a drive ring and a shaft sleeve gap in a preferred embodiment provided by the present invention;

[0041] Fig.17 is a schematic diagram of the arc notch of the drive ring provided by the present invention;

[0042] Fig.18 It is a schematic diagram of the structure of the notch on the pressing sleeve provided by the present invention, that is, Fig.16 AA section view;

[0043] Fig.19 is a schematic diagram of the sleeve notch provided by the present invention, that is, Fig.16 Only the sleeve portion is shown in the K-direction view;

[0044] Fig. 20 is a schematic diagram of gas flow in the heat exchange chamber provided by the present invention;

[0045] Fig.21 It is a schematic diagram of the core part of the magnetic fluid seal;

[0046] Fig. 22 It is a diagram of the sealing mechanism of liquid O-ring.

[0047] Reference numerals list

[0048] 11: cylindrical head screw; 115: second gap; 116: first gap; 12: compression sleeve; 121: outer radial direction; 122: upper axial direction; 123: upper oblique direction; 125: leakage direction; 126: compression sleeve concave surface; 127: compression sleeve end surface; 13: bellows assembly; 131: spring seat; 132: bellows; 133: head seat; 134: moving ring; 14: first wedge pad; 15: second wedge pad; 151: second inclined surface; 152: first inclined surface; 16: first set screw; 21: magnetic column; 211: magnetic field circuit; 22: pole shoe; 221: liquid O-ring; 222: first chamber; 223: second chamber; 224: pole shoe pole tooth; 23: first O-ring; 24 : Second O-ring; 31: Sealing pad; 32: Bearing seat; 321: Hardened layer; 322: Stationary ring; 323: Bearing seat surface; 324: Equipment housing surface; 33: First connecting screw; 34: First spacer; 35: Pressing sleeve; 351: Notch on pressing sleeve; 36: Second connecting screw; 37: Second set screw; 38: Driving ring; 381: Arc notch; 382: Third gap; 39: Retaining ring; 41: Bushing; 411: Step; 412: First bushing notch; 413: Second bushing notch; 414: Bushing end face; 415: Heat exchange chamber; 42: First bearing; 43: Second spacer; 44: Second bearing; 45: Shaft elastic retaining ring; 46: Collecting sleeve; 61: Center line. DETAILED DESCRIPTION

[0049] The following is a detailed description with reference to the accompanying drawings.

[0050] "Ultra-low temperature" refers to a working environment below -40°C or even below -100°C.

[0051] "Cryogenic medium" refers to the cryogenic substance sealed by the sealing device of the present invention. The cryogenic medium may be in liquid or gaseous state, and the temperature is between -100°C and -40°C.

[0052] "Atmospheric environment" refers to the external environment in which the sealing device works. If the sealing device is installed outdoors, the atmospheric environment refers to the outdoor air; if the sealing device is installed indoors, the atmospheric environment refers to the indoor air.

[0053] "Medium side" or "medium end" refers to the side that is relatively closer to the low-temperature medium. For example, if part A is closer to the low-temperature medium than part B, then part B is said to have part A on its medium side. For another example, if the lower end of part A is closer to the low-temperature medium than the upper end, then the lower end of part A is called the medium end.

[0054] "Atmospheric side" or "atmospheric end" refers to the side that is relatively closer to the atmospheric environment. For example, if part C is closer to the atmospheric environment than part D, then part D is said to have part C on its atmospheric side. For another example, if the lower end of part C is closer to the atmospheric environment than the upper end, then the lower end of part C is called the atmospheric end.

[0055] "Mechanical seal operating power" refers to the actual power consumed by the mechanical seal during operation. This parameter is related to the friction between the end faces of the dynamic and static rings of the mechanical seal. The greater the friction, the greater the heat generated by the end faces of the dynamic and static rings during the operation of the mechanical seal, and the greater the power consumed.

[0056] like Figure 1 As shown, the present invention discloses an ultra-low temperature self-heating magnetic fluid sealing device, which includes: a cylindrical head screw 11, a compression sleeve 12, a spring seat 131, a bellows 132, a head seat 133, a moving ring 134, a first wedge-shaped pad 14, a second wedge-shaped pad 15, a first set screw 16, a magnetic column 21, a pole shoe 22, a first O-ring 23, a second O-ring 24, a bearing seat 32, a first spacer sleeve 34, a collecting sleeve 46, a shaft sleeve 41, a first connecting screw 33, a first bearing 42, a second bearing 44, a second spacer sleeve 43, a compression sleeve 35, a driving ring 38, a clamping ring 39, an elastic retaining ring 45 for the shaft, a second set screw 37 and other components.

[0057] like Figure 2 As shown, the sealing device of the present invention is a cartridge seal, in which a mechanical seal, a magnetic fluid seal, a bearing, etc. are arranged in sequence along the axial direction from the medium side to the atmosphere side.

[0058] like Figure 3 and Figure 4 As shown, the mechanical seal may include a bellows assembly 13, a compression sleeve 12, a second wedge pad 15, and a bearing seat 32, wherein the cryogenic medium may fill the radial outer side of the bellows assembly 13 and the compression sleeve 12. The function of the mechanical seal is to prevent a large amount of cryogenic medium from directly contacting the magnetic fluid seal and causing the magnetic fluid seal to fail.

[0059] like Figure 4 As shown, one end of the bellows 132 is welded to the spring seat 131 as a whole, and the other end is welded to the head seat 133 as a whole, and the dynamic ring 134 is integrated with the head seat 133 by shrink sleeve to form a bellows assembly 13. Each welding position of the bellows assembly 13 needs to ensure sealing during welding to prevent low-temperature medium from leaking from the weld.

[0060] like Figure 2 and Figure 3 As shown, a plurality of first set screws 16 arranged along the circumferential direction connect the spring seat 131 and the shaft sleeve 41 .

[0061] like Figure 5As shown, a step 411 is provided on the shaft sleeve 41, and on the medium side direction of the step 411, a collecting sleeve 46, a second wedge-shaped pad 15, a spring seat 131, and a pressing sleeve 12 are arranged in sequence, wherein a plurality of cylindrical head screws 11 are arranged circumferentially between the pressing sleeve 12 and the shaft sleeve 41. In order to ensure that the pressing sleeve 12 can press the spring seat 131, the second wedge-shaped pad 15, and the collecting sleeve 46 onto the step 411 in sequence, a first gap 116 is provided between the pressing sleeve 12 and the shaft sleeve 41. The first gap 116 can ensure that when the cylindrical head screw 11 is tightened, the shaft sleeve end face 414 and the concave surface 126 of the compression sleeve do not contact, but the compression sleeve end face 127 contacts the spring seat 131 first, and when the cylindrical head screw 11 is further tightened, the compression sleeve 12 presses the spring seat 131, the second wedge pad 15, and the collecting sleeve 46 onto the shaft sleeve 41, so that the collecting sleeve 46, the second wedge pad 15, the spring seat 131, the moving ring 134, and the compression sleeve 12 can rotate around the center line 61 with the shaft sleeve 41. After the moving ring 134 of the mechanical seal is driven to rotate, the moving ring 134 can wear relative to the bearing seat 32 to generate heat, thereby affecting the temperature at the magnetic fluid seal.

[0062] like Figure 7 As shown, the first wedge-shaped pad 14 is provided to prevent the cryogenic medium from leaking along the gap between the shaft sleeve 41 and the rotating shaft. Preferably, the first gap 116 provided between the pressing sleeve 12 and the shaft sleeve 41 can also ensure that when the cylindrical head screw 11 is tightened, the pressing sleeve 12 first contacts the first wedge-shaped pad 14, and presses the first wedge-shaped pad 14 while continuing to tighten the cylindrical head screw 11, thereby ensuring that the pressing sleeve 12 can press the first wedge-shaped pad 14 onto the shaft sleeve 41.

[0063] like Figure 2 As shown, the moving ring 134 is directly pressed against the medium side end face of the bearing seat 32, and the end face of the bearing seat 32 close to the medium side is used as the static ring end face of the mechanical seal. With the help of the fitting of the moving ring 134 and the end face of the bearing seat 32, a large amount of low-temperature medium can be blocked from entering the magnetic fluid seal on the atmosphere side. At the same time, since the bearing seat 32 is in direct contact with the pole shoe 22, the number and distance of parts in the heat transfer process are reduced, the heat loss is reduced, and the heat generated by the wear of the mechanical seal end face can be quickly transferred to the pole shoe 22, so that the use temperature of the magnetic fluid can be quickly reached.

[0064] like Figure 8As shown, several first connecting screws 33 distributed circumferentially fix the bearing seat 32 on the equipment housing, wherein a sealing gasket 31 may be installed to prevent the low-temperature medium from leaking from between the bearing seat 32 and the equipment cavity. The sealing gasket 31 is sealed by compression, and in order to ensure that the sealing gasket 31 is compressed by the bearing seat 32, a second gap 115 is provided between the bearing seat 32 and the equipment housing. The second gap 115 can ensure that when the first connecting screw 33 is tightened, the bearing seat surface 323 and the equipment housing surface 324 do not contact, but the medium side end face of the bearing seat 32 first contacts the sealing gasket 31, and the sealing gasket 31 is compressed when the connecting screw 33 is further tightened. The inner diameter of the sealing gasket 31 should be as small as possible, so that the contact area between the low-temperature medium and the bearing seat 32 can be reduced, the heat exchange between the bearing seat 32 and the low-temperature medium can be reduced, and finally the temperature reduction value of the pole shoe 22 can be reduced.

[0065] like Figure 2 As shown, the pole shoe 22 is installed in the bearing seat 32, and the first O-ring 23 and the second O-ring 24 can prevent the cryogenic medium from leaking from the gap between the bearing seat 32 and the pole shoe 22. A plurality of magnetic columns 21 evenly distributed along the circumferential direction are arranged in the outer groove of the pole shoe 22, and the magnetic field formed by the magnetic columns 21 wraps around the pole shoe 22 and the shaft sleeve 41.

[0066] like Fig. 9 As shown, there is a small gap between the pole shoe 22 and the sleeve 41, wherein the magnetic liquid filled in these gaps can form a plurality of liquid O-rings 221 after being constrained by the magnetic field, thereby playing a sealing role. A protrusion extending axially toward the atmosphere side is provided on the collecting sleeve 46, and a protrusion extending axially toward the medium side is provided on the pole shoe 22. The two protrusions are interlaced with each other, thereby forming a first chamber 222. In a static state, the mechanical seal cannot generate heat. At this time, the magnetic liquid has a high viscosity and poor fluidity due to the low temperature, and cannot be smoothly adsorbed in the gap between the pole shoe 22 and the sleeve 41. At this time, the magnetic liquid can be stored in the first chamber 222. When the equipment is running, the heat generated by the mechanical seal increases the temperature of the magnetic liquid, and the viscosity returns to normal. Under the action of the magnetic field, it can be re-adsorbed on the pole shoe 22.

[0067] like Fig.10 As shown, a protrusion extending axially toward the atmosphere is provided on the pole shoe 22, and a protrusion extending axially toward the medium is provided on the shaft sleeve 41, and the two protrusions are interlaced to form a second chamber 223. In a stationary state, the mechanical seal cannot generate heat. At this time, the magnetic liquid has a high viscosity and poor fluidity due to the low temperature, and cannot be smoothly adsorbed in the gap between the pole shoe 22 and the shaft sleeve 41. At this time, the magnetic liquid can be stored in the second chamber 223. When the equipment is running, the heat generated by the mechanical seal increases the temperature of the magnetic liquid, and the viscosity returns to normal. Under the action of the magnetic field, it can be re-adsorbed on the pole shoe 22.

[0068] like Figure 2 As shown, the first bearing 42 and the second bearing 44 are installed in the bearing seat 32. A first spacer 34 can be arranged between the first bearing 42 and the pole shoe 22. The function of the first spacer 34 is to press and position the pole shoe 22 and reduce the magnetic leakage of the pole shoe 22. A second spacer 43 can be arranged between the first bearing 42 and the second bearing 44. The function of the second spacer 43 is to increase the span between the two bearings, improve the bearing positioning accuracy, and improve the overall sealing accuracy. The outer ring of the second bearing 44 is pressed by a press sleeve 35, and the press sleeve 35 is fixed to the bearing seat 32 by a number of second connecting screws 36 arranged in the circumferential direction.

[0069] like Figure 2 and Figure 5 As shown, the inner holes of the first bearing 42 and the second bearing 44 cooperate with the sleeve 41, and the inner ring of the first bearing 42 can be axially positioned by the step 411 of the sleeve 41 to prevent the sleeve 41 from moving axially toward the medium side relative to the first bearing 42 and the second bearing 44; the inner ring of the second bearing 44 can be axially positioned by the shaft elastic retaining ring 45 to prevent the sleeve 41 from moving axially toward the atmosphere side relative to the first bearing 42 and the second bearing 44.

[0070] like Figure 2 As shown, the drive ring 38 is provided with threaded holes arranged along the circumferential direction, and the second set screw 37 is tightened on the rotating shaft through the threaded holes and the through holes on the sleeve 41, so that the sleeve 41 rotates around the center line 61 together with the rotating shaft.

[0071] like Figure 2 and Figure 4 As shown, when assembling the sealing device, the first O-ring 23, the second O-ring 24, the pole shoe 22, and the magnetic column 21 can be assembled into one, and then installed on the bearing seat 32; the first bearing 42, the second bearing 44, the second spacer 43, the shaft sleeve 41, and the shaft elastic retaining ring 45 are assembled into one to form a shaft sleeve assembly; after the first spacer 34 is assembled to the bearing seat 32, the shaft sleeve assembly is pressed into the bearing seat 32, and then the pressing sleeve 35 and the second connecting screw 36 are assembled; finally, the second wedge pad 15 and the bellows assembly 13 are installed on the shaft sleeve 41, and they are positioned with the first set screw 16, and then the first wedge pad 14 and the compression sleeve 12 are installed, and the compression sleeve 12 is fixed to the shaft sleeve 41 with the cylindrical head screw 11 to complete the assembly of the sealing device.

[0072] like Fig.11As shown, the sealing device is composed of a magnetic fluid seal and a mechanical seal, wherein the mechanical seal is located on the medium side and the magnetic fluid seal is located on the atmosphere side. Further, the function of the mechanical seal is to prevent the low-temperature medium from contacting the magnetic fluid seal in large quantities, and the function of the magnetic fluid seal is to prevent the low-temperature medium leaking from the mechanical seal from further leaking into the atmosphere.

[0073] like Fig.11 As shown, the pole shoe 22 is pressed against the bearing seat 32 in the axial direction by the first spacer 34, the first bearing 42, the second spacer 43, the second bearing 44, and the pressing sleeve 35 in sequence through the second connecting screw 36, and the pole shoe 22 is relatively stationary with the equipment housing. The shaft sleeve 41 is tightened on the rotating shaft by the second fixing screw 37, and rotates around the axial center line 61 with the rotating shaft. Therefore, there is relative rotation between the pole shoe 22 and the shaft sleeve 41. In order to ensure that the two parts are not worn, there is a gap between the pole shoe 22 and the shaft sleeve 41. When there is a slight leakage of low-temperature medium between the moving ring 134 and the end face of the bearing seat 32, in order to ensure that the low-temperature medium does not leak into the atmosphere along the gap between the pole shoe 22 and the shaft sleeve 41, these gaps are filled with magnetic liquid. As shown Fig.14 As shown, since the magnetic column 21 is provided, and the pole shoe 22 and the shaft sleeve 41 are both made of magnetic conductive materials, a magnetic field loop 211 can be formed between the pole shoe 22 and the shaft sleeve 41. Fig.15 As shown, under the action of the magnetic field circuit 211, the magnetic liquid can be tightly adsorbed in the gap between the pole shoe 22 and the sleeve 41, and a liquid O-ring 221 arranged in a full circle along the circumferential direction is formed on each tooth tip of the pole shoe 22, thereby sealing the low-temperature medium.

[0074] In order to ensure that the liquid O-ring 221 can be evenly distributed in the circumferential direction, the gap between the pole shoe pole teeth 224 and the sleeve 41 should be in the range of 0.05 to 0.3 mm, and the magnetic liquid needs to have good fluidity. Furthermore, the magnetic liquid contains three raw materials: magnetic nanoparticles, base liquid, and active dispersant. The base liquid and active dispersant are both liquids, generally water, engine oil, glycerin, kerosene, etc. In an environment below -40°C, the viscosity of these liquids will rise rapidly, reaching more than 4000cp, and even become solid. At this time, the liquid O-ring 221 cannot be formed between the pole shoe 22 and the sleeve 41, and thus sealing cannot be achieved. Therefore, it is necessary to control the temperature of the magnetic liquid part to ensure that it is above -40°C. The present invention achieves this by reducing the heat transfer between the low-temperature medium and the seal as a whole, increasing the heat transfer between the mechanical seal and the magnetic liquid, and accelerating the heat transfer between the atmospheric environment and the seal as a whole.

[0075] Preferably, the sealing points in direct contact with the low-temperature medium include: the first wedge pad 14 between the sleeve 41, the rotating shaft and the clamping sleeve 12; the sealing gasket 31 between the bearing seat 32 and the sealing cavity; the second wedge pad 15 between the spring seat 131, the sleeve 41 and the collecting sleeve 46; and the sealing structure between the moving ring 134 and the end face of the bearing seat 32 close to the medium side.

[0076] like Figure 7 As shown, the sleeve 41 and the first wedge-shaped pad 14 fit together at the first inclined surface 152. When the compression sleeve 12 compresses the first wedge-shaped pad 14, the first inclined surface 152 between the sleeve 41 and the first wedge-shaped pad 14 is tightly compressed, and at the same time, the inner hole of the first wedge-shaped pad 14 is deformed and tightly hugged on the outer circle of the rotating shaft, so that the first wedge-shaped pad 14 can prevent the low-temperature medium from leaking along the upper axial direction 122 and the upper oblique direction 123, wherein the upper axial direction 122 is the direction of the center line 61 pointing to the atmosphere side, and the upper oblique direction 123 is the direction along the first oblique surface 152 pointing to the atmosphere side. In order to ensure the sealing and low-temperature adaptability of the first wedge-shaped pad 14, the material of the first wedge-shaped pad 14 can be selected from a metal ring with lower hardness, preferably copper or aluminum.

[0077] like Figure 7 As shown, since the first wedge-shaped pad 14 is located at the medium end of the sleeve 41, the contact area between the low-temperature medium and the sleeve 41 can be minimized, and this contact area is the heat exchange area between the low-temperature medium and the sleeve 41. The reduction of the heat exchange area can reduce the heat transfer of the low-temperature medium to the sleeve 41, ensuring that the temperature of the sleeve 41 is as high as possible. Fig.11 As shown, taking a shaft diameter of 40 mm as an example, after actual measurement, assuming that the temperature of the low-temperature medium is -100°C and the atmospheric environment temperature is 25°C, under this heat exchange area, the temperature of the shaft sleeve 41 corresponding to the inner hole of the pole shoe 22 is -47°C.

[0078] like Figure 6 As shown, the second wedge pad 15 and the collecting sleeve 46 fit together at the second inclined surface 151. When the spring seat 131 presses the second wedge pad 15, the spring seat 131 and the end surface of the second wedge pad 15 fit together and seal, and at the same time, the inner hole of the second wedge pad 15 is deformed and tightly hugs the outer circle of the sleeve 41, so that the second wedge pad 15 can prevent the low-temperature medium from leaking along the upper axial direction 122 and the outer radial direction 121, wherein the outer radial direction 121 is a direction along the diameter pointing away from the center line 61. In order to ensure the sealing and low-temperature adaptability of the second wedge pad 15, the material of the second wedge pad 15 can be selected from a metal ring with lower hardness, preferably copper or aluminum.

[0079] like Figure 8As shown, when the first connecting screw 33 is tightened, the sealing gasket 31 can be pressed against the device housing by the bearing seat 32, thereby achieving sealing. In order to ensure the sealing and low temperature adaptability of the sealing gasket 31, the material of the sealing gasket 31 can be a metal ring with lower hardness, preferably copper or aluminum.

[0080] like Figure 8 As shown, since the sealing gasket 31 is located at the medium end of the bearing seat 32, the contact area between the low-temperature medium and the bearing seat 32 can be minimized, and this contact area is the heat exchange area between the low-temperature medium and the bearing seat 32. The reduction of the heat exchange area can ensure that the temperature of the bearing seat 32 is as high as possible. Fig.11 As shown, taking a shaft diameter of 40 mm as an example, after actual measurement, assuming that the temperature of the low-temperature medium is -100°C and the atmospheric environment temperature is 25°C, under this heat exchange area, the temperature at the inner hole of the pole shoe 22 is -52°C.

[0081] like Fig.11 As shown, based on the influence of the spring force and the medium force, the end face of the moving ring 134 can fit tightly with the lower end face of the bearing seat 32. When the shaft is running, the relative rotation between the moving ring 134 and the bearing seat 32 can cause wear. The bearing seat 32 can be used as a static ring of a bellows mechanical seal. In order to ensure that the end face of the bearing seat 32 is not damaged by wear and tear during the relative rotation with the moving ring 134, resulting in failure, some parameters can be specified. For example, the material of the moving ring 134 is preferably a graphite material with good self-lubricating properties, as a matching soft ring; the material of the bearing seat 32 needs to select a suitable stainless steel according to the low-temperature medium. This is because from the perspective of material properties, the higher the hardness of the material, the more wear-resistant it is. Therefore, the hard ring material of the mechanical seal is generally silicon carbide or tungsten carbide with very high hardness. However, in this seal, since the bearing seat 32 is used as a mechanical seal moving ring, it also needs to assume the functions of positioning the bearing, connecting the seal and the equipment housing, etc. If the bearing seat 32 is made of brittle materials such as silicon carbide or tungsten carbide, it is easy to crush the bearing seat 32 when the first connecting screw 33 is tightened. like Fig.12 As shown, the hardness of stainless steel is generally less than 40HRC. Under this hardness, the end face of the bearing seat 32 will quickly wear the driven ring 134 destructively, resulting in a large amount of leakage of the low-temperature medium between the driven ring 134 and the end face of the bearing seat 32 along the leakage direction 125. Therefore, a metal surface treatment process can be used to form a hardened layer 321 on the lower end face of the bearing seat 32, wherein the metal surface treatment process can be spraying hard alloy, surfacing hard alloy, etc. Further, after the metal surface treatment process, the end face hardness of the bearing seat 32 is required to be ≥55HRC.

[0082] like Fig.13 As shown, if the static ring 322 is designed alone, the axial distance between the end face of the dynamic ring 134 and the pole shoe 22 is b; Fig.12As shown, if the bearing seat 32 is directly used as a stationary ring, the axial distance between the end face of the moving ring 134 and the pole shoe 22 is a. The dimension a is the axial thickness of the bearing seat 32, and the dimension b includes the axial thickness of the bearing seat 32 and the axial thickness of the stationary ring 322, so b>a. From the perspective of heat transfer, the shorter the distance, the lower the heat loss during the heat transfer process. Therefore, when the bearing seat 32 is directly used as a stationary ring, the heat generated by the friction between the moving ring 134 and the bearing seat 32 can be quickly transferred to the pole shoe 22, reducing the heat transfer loss and effectively increasing the working temperature of the core position of the magnetic fluid seal.

[0083] Take a 40mm shaft diameter mechanical seal as an example: Assume the inner diameter of the end face is D 1 (mm), the end face outer diameter is D 2 (mm), balanced diameter is D i (mm), spring force is F n (N), the friction coefficient of the end faces of the dynamic and static rings is f, the speed is n (rpm), the liquid film stiffness is λ, and the medium pressure is P (Pa), then the mechanical seal operating power N can be calculated from the mechanical seal related formula A (kW):

[0084]

[0085] Among them, A is the end surface area of ​​the mechanical seal dynamic ring, and its calculation formula is:

[0086]

[0087] k is the ratio between the effective action area of ​​the low temperature medium on the dynamic ring and the end surface area, and its calculation formula is:

[0088]

[0089] The operating power of a mechanical seal represents the power consumed by the equipment motor in order to overcome the relative friction between the dynamic and static rings of the mechanical seal during its operation. The greater the power consumed, the greater the relative friction between the dynamic and static rings of the mechanical seal, which further indicates that the greater the heat generated by the mechanical seal during operation, which is the process of converting kinetic energy into thermal energy. Different mechanical seal design parameters can result in different mechanical seal operating powers.

[0090] When the operating power of the mechanical seal is known, the heat generated by the mechanical seal within 1 hour can be inferred by the following formula: Q = N A *3600 (Kj), and then set the heat transfer efficiency constant a to a range of 0.4 to 0.8, from which the temperature rise at the pole shoe 22 can be inferred. The following table shows the theoretical and actual temperature rises at the tooth tip position of the inner hole of the pole shoe 22 at the same speed and pressure for three mechanical seals with different design parameters.

[0091] parameter Theoretical temperature rise (℃) Measured temperature rise (℃) Parameter 1 18.3 16.2 Parameter 2 27.5 26.8 Parameter three 41.2 43.2

[0092] According to the previous measured results, in a -100°C low-temperature medium environment, the temperatures of the sleeve 41 and the pole shoe pole tooth 224 are -47°C and -55°C respectively. When reasonable parameters are selected for the mechanical seal, the temperature rise of the mechanical seal can offset the heat transfer effect of the low-temperature medium on the mechanical seal, so that the seal can meet the -100°C operating temperature.

[0093] Optionally, if the atmospheric environment temperature is greater than -40°C, the structures of the sleeve 41 and the drive ring 38 can be changed to improve the heat exchange efficiency between the sleeve 41 and the atmospheric environment, so as to increase the temperature of the position of the pole shoe 22 on the sleeve 41 to meet the operating temperature of the magnetic liquid.

[0094] like Fig.16 As shown, a heat exchange chamber 415 can be formed between the shaft sleeve 41 and the rotating shaft, and the gas in the heat exchange chamber 415 is converted into low-temperature gas after heat exchange with the shaft sleeve 41 and the rotating shaft. Fig.17 As shown, the driving ring 38 is provided with an arc notch 381, and the number of the arc notches 381 of the driving ring 38 is preferably 2 to 30. The arc notches 381 generally extend outward from the inner diameter of the driving ring 38 in the radial direction, and the circumferential cross-sectional area of ​​the arc notches 381 gradually increases as it extends outward. Fig.17 When the driving ring 38 rotates in the direction shown, due to the change in the cross-sectional area of ​​the arc notch 381, the gas on the radial outer side of the driving ring 38 can be compressed to the radial inner side, such as Fig.17 In order to ensure the compression effect, some parameters can be specified. For example, the ratio of the outer axial cross-sectional width c of the arc notch 381 to the inner axial cross-sectional width d of the arc notch 381 is in the range of 2 to 10. The depth e of the arc notch 381 can be a fixed value in the range of 1 to 10 mm. The depth of the arc notch 381 can also gradually increase as it extends outward, in the range of 1 to 10 mm. Fig.16 As shown, in order to ensure the compression effect, the third gap 382 between the drive ring 38 and the pressing sleeve 35 has a value ranging from 0.5 to 5 mm.

[0095] Fig.18 for Fig.16 For the convenience of explanation, only the cross section of the pressing sleeve 35 is shown. Fig.18 As shown, the pressing sleeve 35 is provided with a pressing sleeve upper notch 351 , wherein when the driving ring 38 rotates, the outer gas can enter the heat exchange chamber 415 through the pressing sleeve upper notch 351 after being compressed.

[0096] Fig.19 for Fig.16For the convenience of explanation, only the shaft sleeve 41 is shown in the K-direction view. Fig.19 As shown, the shaft sleeve 41 is provided with a first shaft sleeve notch 412 and a second shaft sleeve notch 413 , wherein during assembly, the notch 351 on the pressing sleeve and the first shaft sleeve notch 412 of the shaft sleeve 41 may correspond one to one.

[0097] Fig. 20 Schematic diagram of gas flow, the solid arrows in the figure are the gas in the outer atmosphere, the temperature of this gas is higher than the temperature of the gas in the heat exchange chamber 415, that is, the higher temperature gas (also called the first gas); the dotted arrows are the gas in the heat exchange chamber 415, this gas has undergone heat exchange with the low-temperature shaft and the sleeve 41, the temperature is lower than the temperature of the gas in the atmosphere, and is the lower temperature gas (also called the second gas). Fig. 20 As shown, when the driving ring 38 rotates, the outside higher temperature gas is compressed and enters the heat exchange chamber 415 through the notch 351 on the press sleeve and the notch 412 on the first sleeve. After the outside higher temperature gas enters the heat exchange chamber 415, it exchanges with the lower temperature gas in the heat exchange chamber 415, and can bring part of the lower temperature gas in the heat exchange chamber 415 out from the notch 413 on the second sleeve. In order to ensure that the higher temperature gas in the atmosphere is fully exchanged with the gas in the heat exchange chamber 415, the notch 351 on the press sleeve and the notch 412 on the first sleeve correspond to each other when assembled, and from the AA cross-sectional view (as shown in FIG. Fig.18 ) or K-direction view (as shown Fig.19 As shown in FIG. 1 , the cross-sectional area of ​​the notch 351 on the press sleeve and the notch 412 on the first sleeve are the same, and the cross-sectional area should be greater than or equal to 150 mm 2 ; The area ratio of the second sleeve notch 413 to the first sleeve notch 412 is in the range of 0.5 to 0.8.

[0098] Take 40mm shaft diameter seal as an example. Fig.16 As shown, the notch 351 on the pressing sleeve, the notch 412 on the first sleeve and the notch 413 on the second sleeve take the same design value. When the shaft speed is 3000 rpm, the atmospheric environment temperature is 25°C, and the low-temperature medium temperature is -100°C, the gas temperature in the heat exchange chamber 415 with the above-mentioned reasonably designed notches increases by 5°C compared to the case without these notches.

[0099] After the sealing device is installed on the equipment, a low-temperature medium is introduced into the equipment, such as Fig.12 As shown, under the action of spring force and medium pressure, the movable ring 134 can be pushed toward the bearing seat 32, and the end face of the movable ring 134 fits with the medium side end face of the bearing seat 32 to prevent the low-temperature medium from leaking from the outer diameter to the inner diameter along the end face of the movable ring 134. Fig.11As shown, due to the initial blocking between the end face of the moving ring 134 and the end face of the bearing seat 32, the low-temperature medium will not directly transfer heat with the magnetic liquid, and can only exchange heat with the pole shoe 22 through the shaft sleeve 41 and the bearing seat 32 under the influence of the temperature difference (two substances with different temperatures in contact will spontaneously exchange heat). Compared with the pole shoe 22 directly exchanging heat with the low-temperature medium, the indirect heat exchange through the shaft sleeve 41 and the bearing seat 32 increases the difficulty of heat exchange, so that the temperature of the pole shoe 22 will not be too low. Under certain design conditions, when the temperature of the low-temperature medium is -100°C, the temperature of the pole shoe 22 is close to -52°C. In addition, when the mechanical seal is running, due to the mutual friction between the end face of the moving ring 134 and the end face of the bearing seat 32, the heat will also be transferred to the pole shoe 22, increasing the temperature of the pole shoe 22. Under certain design conditions, the temperature rise of the pole shoe 22 can reach 43.2°C. Therefore, under this design condition, the temperature at the pole shoe 22 is -8.8°C, which meets the use requirement of the magnetic liquid at -40°C. At this temperature, the viscosity of some magnetic liquids can be less than 500cp, and the magnetic liquid has good fluidity. Since the sealing device is designed with a permanent magnet inside, and the sleeve 41 and the pole shoe 22 are both made of magnetic conductive materials, a magnetic field (such as Fig.14 As shown in the figure, under the action of the magnetic field, the magnetic liquid with good magnetic fluidity can be adsorbed between the tooth tip of the pole shoe 22 and the shaft sleeve 41 to form a plurality of liquid O-rings 221. Each liquid O-ring 221 can seal a certain pressure. Under the action of a plurality of liquid O-rings 221, a small amount of low-temperature medium with a certain pressure leaking from the mechanical seal can be completely sealed.

[0100] It should be noted that the above-mentioned specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the present invention specification and its drawings are illustrative and do not constitute a limitation of the claims. The scope of protection of the present invention is defined by the claims and their equivalents. The present invention specification contains multiple inventive concepts, such as "preferably" or "according to a preferred embodiment", which means that the corresponding paragraph discloses an independent concept, and the applicant reserves the right to file a divisional application based on each inventive concept. Throughout the text, the features guided by "preferably" are only an optional method and should not be understood as a must-have setting. Therefore, the applicant reserves the right to abandon or delete the relevant preferred features at any time.

Claims

1. An ultra-low temperature self-heating magnetic fluid sealing device, characterized in that: It includes: Mechanical seals, magnetic fluid seals and bearings are arranged in sequence from the medium side to the atmosphere side along the axial direction, wherein: The mechanical seal comprises a moving ring (134) that rotates synchronously with the shaft sleeve (41) and a bearing seat (32) fixed to the equipment housing, wherein the medium-side end face of the bearing seat (32) can directly serve as the static ring end face of the mechanical seal, so that the moving ring (134) is pressed against the medium-side end face of the bearing seat (32) to form an end face seal; The magnetic fluid seal comprises a pole shoe (22) installed in the bearing seat (32) and a plurality of magnetic columns (21) arranged in a groove outside the pole shoe (22); a gap for filling with magnetic liquid can be formed between the pole shoe (22) and the shaft sleeve (41); the magnetic liquid filled in the gap is constrained by the magnetic field formed by the magnetic columns (21) to form a plurality of liquid O-rings (221).

2. The sealing device according to claim 1, characterized in that: The movable ring (134) is integrated with the head seat (133) by means of a shrink fit, the head seat (133) is connected to one end of the bellows (132), and the other end of the bellows (132) is connected to the spring seat (131) to assemble and form a bellows assembly (13), wherein the medium side end surface of the spring seat (131) is in contact with the compression sleeve end surface (127) of the compression sleeve (12) close to the atmosphere.

3. The sealing device according to claim 1 or 2, characterized in that: A plurality of cylindrical head screws (11) are arranged circumferentially between the clamping sleeve (12) and the shaft sleeve (41), and a first gap (116) is also provided, so that when the cylindrical head screws (11) are tightened, the shaft sleeve end face (414) of the shaft sleeve (41) close to the medium side and the clamping sleeve concave surface (126) in the groove of the clamping sleeve (12) do not contact, but the clamping sleeve end face (127) contacts the spring seat (131) first.

4. The sealing device according to any one of claims 1 to 3, characterized in that: A first wedge-shaped pad (14) is provided between the shaft sleeve (41), the rotating shaft and the pressing sleeve (12); a second wedge-shaped pad (15) is provided between the spring seat (131), the shaft sleeve (41) and the collecting sleeve (46); contact surfaces of the first wedge-shaped pad (14) and the second wedge-shaped pad (15) respectively form a first inclined surface (152) and a second inclined surface (151); wherein the first inclined surface (152) contacts the shaft sleeve (41), and the second inclined surface (151) contacts the collecting sleeve (46).

5. The sealing device according to any one of claims 1 to 4, characterized in that: A protrusion extending axially toward the atmosphere is provided on the collecting sleeve (46), and a protrusion extending axially toward the medium is provided on the pole shoe (22), and the two protrusions are staggered to form a first chamber (222); a protrusion extending axially toward the atmosphere is provided on the pole shoe (22), and a protrusion extending axially toward the medium is provided on the shaft sleeve (41), and the two protrusions are staggered to form a second chamber (223), wherein the first chamber (222) and the second chamber (223) are capable of storing magnetic liquid.

6. The sealing device according to any one of claims 1 to 5, characterized in that: The magnetic field formed by the magnetic column (21) can form a magnetic field loop (211) between the pole shoe (22) and the shaft sleeve (41); under the action of the magnetic field loop (211), the magnetic liquid can be adsorbed in the gap between the pole shoe (22) and the shaft sleeve (41), thereby forming a liquid O-ring (221) arranged in a full circle along the circumferential direction at each tooth tip of the pole shoe (22).

7. The sealing device according to any one of claims 1 to 6, characterized in that: The bearing comprises a first bearing (42) and a second bearing (44) installed in a bearing seat (32), a second spacer sleeve (43) for increasing the span between the two bearings is arranged between the first bearing (42) and the pole shoe (22), and a first spacer sleeve (34) for pressing and positioning the pole shoe (22) is arranged between the first bearing (42) and the pole shoe (22).

8. The sealing device according to any one of claims 1 to 7, characterized in that: The moving ring (134) is connected to the shaft sleeve (41) via a first set screw (16); a step (411) is provided on the shaft sleeve (41) for positioning the first bearing (42); and the atmospheric end of the shaft sleeve (41) positions the second bearing (44) via a shaft elastic retaining ring (45).

9. The sealing device according to any one of claims 1 to 8, characterized in that: A plurality of pressing sleeve upper notches (351) are arranged on a pressing sleeve (35) for pressing the outer ring of a second bearing (44), and a first sleeve notch (412) corresponding to the pressing sleeve upper notch (351) and a second sleeve notch (413) surrounded by the first sleeve notch (412) are arranged on the sleeve (41).

10. The sealing device according to any one of claims 1 to 9, characterized in that: The gas in the heat exchange chamber (415) formed between the shaft sleeve (41) and the rotating shaft can be cooled down after heat exchange with the shaft sleeve (41) and the rotating shaft to form a second gas. When the drive ring (38) rotates, the first gas in the outer atmospheric environment enters the heat exchange chamber (415) through the notch (351) on the compression sleeve and the notch (412) of the first shaft sleeve after compression, and exchanges with the second gas, and a part of the second gas is taken out from the notch (413) of the second shaft sleeve.

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