Vertical bottom-in liquid medium magnetic liquid seal and working method

Abstract

The invention provides a vertical bottom-in liquid medium magnetic liquid seal and a working method, the vertical bottom-in liquid medium magnetic liquid seal comprises a rotating cover, the rotating cover is inversely buckled on a shaft sleeve in an inverted U shape and is fastened on the shaft sleeve through a connecting screw, a part of a sealing seat is installed in the rotating cover, and a bearing and a pole shoe assembly are installed between the shaft sleeve and the sealing seat. The pole shoe assembly is internally provided with magnetic liquid for isolating the atmospheric environment from a sealed liquid medium, the other part of the sealing seat is provided with an air inlet, an air channel is formed in the sealing seat and communicated to a gap between the top of the sealing seat and the rotating cover, and air is introduced into the air inlet to prevent the liquid medium from entering the pole shoe assembly. The axial contact position of the rotating cover and the sealing seat is provided with a reverse spiral groove for preventing crystallization working medium accumulation. The problem of vertical bottom-entering type liquid medium sealing is solved, and the application range of magnetic liquid sealing is expanded.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of magnetic liquid sealing, and particularly relates to a vertical bottom-into-liquid medium magnetic liquid sealing. BACKGROUND

[0002] The main features of the magnetic liquid sealing include no wear, high sealing plugging, no leakage, high reliability and high efficiency transmission. These features make the magnetic liquid sealing have a wide application prospect in vacuum sealing, and in the case of liquid sealing, due to the contact of the liquid medium and the interface of the magnetic liquid, the interface instability appears in the movement [2]-[3] , so the use is not optimistic under the working condition of direct contact between the magnetic liquid and the liquid medium.

[0003] Wang Hujun, He Xinzh, Zhang Yanjuan. Experimental Study on Life of Gas-separation MHD Water Seal, published in Vacuum Science and Technology Journal, No. 12, 2020. A gas-separation MHD sealing structure design is introduced, which is composed of two parts, the compressed gas part below the gas-separation device and the compressed gas-separation sealed liquid part above the gas-separation device.

[0004] The main component in the gas-separation device is the air ring, and the compressed gas in the air ring separates the magnetic fluid from the sealed liquid. The air ring is designed with a compressed gas passage connected to the air inlet.

[0005] However, the gas interface of the sealing structure gas-separation assembly is at the bottom, and the liquid interface is at the top. Due to the existence of gravity or working pressure, there are factors of unstable nitrogen pressure and vibration of the sealing structure in actual operation, which may lead to sealing failure. Although the sealing structure mentions that it has successfully operated for 120 hours in the experiment, it fails to meet the checking requirements for the sealing requirements of the magnetic fluid for several years.

[0006] Therefore, the following factors should be considered in the magnetic liquid sealing: (1) Long-period operation may cause mixing of liquid and isolation gas, resulting in reduction of isolation gas; (2) The air tightness of the entire inverted structure is affected by the air tightness of the O-ring gap in the connecting piece, and a small amount of air leakage may occur, resulting in reduction of isolation gas; (3) The volatiles of the liquid medium may cause the environment of the isolation gas to deteriorate, such as corrosive gas; (4) The phase of the liquid medium may change, such as crystallization. SUMMARY

[0007] The present application aims at solving the defects of the prior art, and provides a vertical bottom-liquid medium magnetic liquid seal which can still operate normally without external gas, because the air in the inverted cover can always reach pressure balance with the liquid medium, and finally forms a stable gas isolation space, thereby solving the problem of unstable liquid medium interface of the magnetic liquid seal.

[0008] The present application adopts the following technical scheme: The vertical bottom-liquid medium magnetic liquid seal comprises a rotating cover, the rotating cover is inverted U-shaped and inverted on a shaft sleeve, and is fastened on the shaft sleeve through connecting screws, a part of a sealing seat is installed in the rotating cover, bearings and pole shoe assemblies are installed between the shaft sleeve and the sealing seat, the pole shoe assemblies have magnetic liquid for sealing the bearings, another part of the sealing seat has an air inlet, the sealing seat has an air channel, the air channel is communicated to the gap between the top of the sealing seat and the rotating cover, the air inlet is communicated to the gas, the liquid working medium is prevented from entering the pole shoe assemblies, and the rotating cover and the sealing seat have helical grooves at the axial contact positions for preventing impurities from entering.

[0009] The sealing seat is fastened on the cover plate through screws.

[0010] The shaft sleeve is provided with a shaft elastic retainer ring for positioning the lower part of the bearing, the upper parts of the bearings are fixed by the protrusions of the shaft sleeve and the sealing seat, the lower part of the pole shoe assembly is positioned by the protrusions of the shaft sleeve and the sealing seat, and the upper part of the pole shoe assembly is provided with an isolation seal, and the sealing seat at the upper part of the isolation seal is provided with a hole elastic retainer ring for positioning the upper part of the pole shoe assembly.

[0011] O-shaped sealing rings are arranged on the rotating cover and the shaft sleeve in the axial direction for axial sealing.

[0012] The shaft sleeve is fixed on the vertical shaft through the driving sleeve at the bottom.

[0013] A check valve is arranged on the air channel to prevent backflow of the gas The pole shoe assembly comprises a spacer, a permanent magnet, a magnetic pole shoe and an O-shaped sealing ring, the magnetic pole shoe is divided into three parts, the side of the magnetic pole shoe facing the shaft sleeve is rectangular tooth-shaped, and the side of the magnetic pole shoe facing the sealing seat is provided with grooves for mounting the O-shaped sealing ring, and the spacer and the permanent magnet are arranged between the upper magnetic pole shoe and the middle magnetic pole shoe and between the middle magnetic pole shoe and the lower magnetic pole shoe.

[0014] The present application also provides a working method of the vertical bottom-liquid medium magnetic liquid seal, comprising: After the components are positioned on the vertical shaft, N2 is introduced into the air channel through the air inlet of the sealing seat, and the equipment is started to rotate the vertical shaft, because of the existence of the gas pressure, the liquid working medium cannot enter the pole shoe assembly through the gap between the rotating cover and the sealing seat.

[0015] Since the invention is installed at the bottom of the equipment (reaction kettle), the flange part of the sealing seat is immersed in the liquid medium, and the sealing seat for accommodating the bearing and pole shoe assembly will not have liquid medium entering due to the N2 inlet.

[0016] For the intermittent N2 inlet mode (i.e. once N2 is inhaled, N2 will be inhaled during maintenance), the liquid medium liquid level is at the bottom of the rotating cover, and the N2 in the gap between the rotating cover and the sealing seat during installation will be compressed by the rotating cover gravity to reach a balanced state. The compressed gas is discharged into the equipment (reaction kettle) through the spiral groove of the rotating cover.

[0017] For the continuous N2 inlet mode, the outside and top of the rotating cover are in contact with the liquid medium, and the N2 in the gap between the rotating cover and the sealing seat during installation will reach a new balanced state due to the rotating cover gravity and the liquid medium.

[0018] The beneficial effects of the present invention are: 1. Optimize the sealing environment: The disadvantage of sealing liquid with magnetic liquid for only a few days is converted into the advantage of sealing gas for several years. Since the magnetic liquid directly contacts the sealing liquid medium, it is not only limited to the interface between the two liquids, which leads to a decrease in sealing capacity, but also inevitably leads to contamination of the sealed liquid medium and corrosion of the magnetic liquid. Instead of considering not mixing the magnetic liquid with the liquid medium, the present invention changes the structure from an engineering perspective to provide a good sealing environment for the magnetic liquid.

[0019] 2. High reliability of structure: The present sealing has good self-adaptability under basic working conditions without the need for external energy input. Within the sealing pressure capacity, the gas in the rotating cover at the bottom of the sealed liquid medium will be compressed by the liquid medium self-weight and the rotating cover gravity, and finally reach a balance with the liquid medium self-weight. The macroscopic phenomenon is that the liquid level no longer rises in the rotating cover and cannot enter the pole shoe assembly to contact the magnetic liquid.

[0020] 3. Simple structure: The rotating cover used in this invention occupies a small space and has a simple structure, which is easy to standardize. The rotating cover uses the weight of the liquid medium and the self-weight or the rotating cover self-weight to compress the internal gas to achieve isolation, so there is no need for too strict processing requirements.

[0021] 4. Strong compatibility: The gas isolation mentioned in this invention uses a non-contact method, which is compatible with the long-term sealing of the magnetic liquid, maintenance-free, low friction, and other characteristics, and can well adapt to the magnetic liquid sealing. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The structure of the present invention is shown in the figure; Figure 2 The structure of the driving sleeve is shown in the figure; Figure 3 This is a schematic diagram of the structure of the elastic retaining ring for holes; Figure 4 This is a schematic diagram of the structure of the elastic retaining ring for the shaft; Figure 5 Schematic diagram of the cover structure; Figure 6 Schematic diagram of the bearing retaining ring structure; (a) is a schematic diagram of the outer structure of the bearing retaining ring, and (b) is a schematic diagram of the inner structure of the bearing retaining ring; Figure 7 Schematic diagram of the sealing seat structure; Figure 8 Schematic diagram of the rotating cover structure; Figure 9 Schematic diagram of the shaft sleeve structure; Figure 10 Schematic diagram of the isolation and sealing structure; Figure 11 Schematic diagram of the pole shoe assembly structure.

[0023] In the figure: 1-drive sleeve, 2-shaft sleeve, 3-cover plate, 4-shaft elastic ring, 5-O-ring, 6-bearing, 7-bearing retaining ring outer, 8-bearing retaining ring inner, 9-seal seat, 10-pole shoe assembly, 11-rotating cover, 12-isolation seal, 13-hole elastic ring, 14-connecting screw; 100-spacer, 101-permanent magnet, 102-magnetic pole shoe, 5-O-ring.

[0024] Interface instability: The rotation of the magnetic liquid and the stationary liquid medium cause mixing at the liquid interface, which may lead to changes in the properties of the magnetic liquid or loss of the magnetic liquid. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, the vertical bottom-entry liquid medium magnetic liquid seal of the present invention includes a drive sleeve 1, a shaft sleeve 2, a cover plate 3, an elastic circlip 4 for the shaft, an O-ring 5, a bearing 6, an outer bearing circlip 7, an inner bearing circlip 8, a sealing seat 9, a pole shoe assembly 10, a rotating cover 11, an isolation seal 12, an elastic circlip 13 for the hole and a connecting screw 14.

[0027] The shaft sleeve 2 is installed on the vertical shaft, and the bottom of the shaft sleeve 2 is provided with a driving sleeve 1. The driving sleeve 1 is fixed to the vertical shaft through internal screws, so that the shaft sleeve 2 rotates synchronously with the vertical shaft.

[0028] As shown in Figure 2 , the driving sleeve 1 is a wedge-shaped fastening device. With the screwing of the screw, the shaft sleeve 2 is firmly fixed on the vertical shaft, and is widely used in the mechanical industry, and is also known as an expansion sleeve. The shaft sleeve 2 is fastened on the vertical shaft through the driving sleeve 1 and rotates synchronously with the vertical shaft. The shaft sleeve 2 is sealed with the O-shaped sealing ring 5, and the dynamic sealing between the shaft sleeve 2 and the bearing 6 is borne by the magnetic liquid, as shown in Figure 9 .

[0029] The upper side of the driving sleeve 1 is provided with a cover plate 3, and the cover plate 3 is connected with the sealing seat 9 through screws, which is used for installing the bearing 6, as shown in Figure 5 . The shaft sleeve 2 parallel to the cover plate 3 is provided with an elastic shaft retainer 4, which is used for positioning the bearing 6, as shown in Figure 4 . The sealing seat 9 is installed on the cover plate 3, and the sealing seat 9 is provided with the bearing 6, the pole shoe assembly 10 and the isolation seal 12 from bottom to top in the isolation cavity of the shaft sleeve 2. The bearing 6 and the pole shoe assembly 10 are fixed and positioned through the shaft sleeve and the protrusion of the sealing seat 9. The isolation seal 12 is an auxiliary sealing structure similar to a skeleton oil seal, which is used for reducing the influence of the isolation gas on the pole shoe assembly 10 when entering the isolation cavity. As shown in Figure 10 , the sealing seat 9 on the upper side of the isolation seal 12 is provided with a hole elastic retainer 13, which is used for limiting the axial position of the pole shoe assembly 10, as shown in Figure 3 . The shaft sleeve 2 and the sealing seat 9 are provided with a rotating cover 11 which is installed on the shaft sleeve 2 through connecting screws 14. The rotating cover 11 is provided with an O-shaped sealing ring 5 on the axial end surface in contact with the shaft sleeve 2. With respect to the background art, the O-shaped sealing ring 5 is used as a dynamic seal. However, the dynamic seal will cause sealing failure and short sealing time (usually several months), which is not suitable for the design requirement of the magnetic liquid sealing (usually several years). In the present application, the O-shaped sealing ring 5 is designed to be relatively static, and the O-shaped sealing ring 5 is a static seal, which can meet the design requirements of the magnetic liquid sealing.

[0030] The sealing seat 9 has an air channel, which is connected with an air inlet at the end, and the other end of the air channel is communicated to the top of the sealing seat 9, so that the gas is introduced into the gap between the rotating cover 11 and the sealing seat 9 when they are installed. N2 is introduced into the air inlet intermittently / continuously, and the pressure is greater than normal pressure. The axial end of the rotating cover 11 in contact with the sealing seat 9 has a spiral groove to prevent external impurities from entering.

[0031] The sealing seat 9 is used for accommodating the bearing 6, the pole shoe assembly 10 and other components, and is a sealed main body supporting structure. Figure 7

[0032] The rotating cover 11 is connected with the shaft sleeve 2 to form a reverse "U" type closed gas space, and the magnetic liquid is isolated from the liquid medium in the non-active state, so that the bottom entry magnetic liquid sealing problem is solved. Figure 8

[0033] Further, the bearing 6 is provided with the inner bearing spacer 8 and the outer bearing spacer 7, and the bearing spacer is used for supporting the bearing 6. Figure 6

[0034] Further, the pole shoe assembly 10 comprises the spacer 100, the permanent magnet 101, the magnetic pole shoe 102 and the O-shaped sealing ring 5, the magnetic pole shoe 102 is divided into three parts, the side of the magnetic pole shoe 102 facing the shaft sleeve 2 is rectangular toothed, and the side of the magnetic pole shoe 102 facing the sealing seat 9 is provided with a groove for mounting the O-shaped sealing ring 5, and the spacers 100 and the permanent magnets 101 are mounted between the upper magnetic pole shoe and the middle magnetic pole shoe and between the middle magnetic pole shoe and the lower magnetic pole shoe. Figure 11

[0035] The pole shoe assembly 10 is a magnetic liquid sealing main body, and the magnetic liquid is sealed by constructing a permanent magnet circuit to block the sealing gap.

[0036] Further, the sealing seat 9 is provided with the O-shaped sealing ring 5 at the connection between the sealing seat 9 and the kettle body.

[0037] Further, the check valve is mounted on the gas channel to prevent backflow of the gas.

[0038] The working method of the vertical bottom entry liquid medium magnetic liquid sealing comprises the following steps: installing and positioning the shaft sleeve 2, the driving sleeve 1, the bearing 6, the pole shoe assembly 10 and other components on the vertical shaft.

[0039] Since the sealing seat 9 is installed at the bottom of the device (the reaction kettle), the flange part of the sealing seat 9 is immersed in the liquid medium, and the sealing seat 9 used for accommodating the bearing 6 and the pole shoe assembly is not entered by the liquid medium due to the N2.

[0040] ​​​​For the intermittent N2 mode (that is, after the N2 is introduced, the N2 is introduced during the maintenance), the liquid medium liquid level is at the bottom of the rotating cover 11, and the N2 in the gap between the rotating cover 11 and the sealing seat 9 during installation will be compressed by the gravity of the rotating cover 11 to reach a balanced state. The compressed gas is discharged into the equipment (reaction kettle) by the rotating cover 11 through the spiral groove.

[0041] For the continuous N2 mode, the rotating cover 11 outside and top are in contact with the liquid medium, and the N2 in the gap between the rotating cover 11 and the sealing seat 9 during installation will reach a new balanced state due to the gravity of the rotating cover and the liquid medium.

[0042] Start the device to rotate the vertical shaft. Due to the existence of gas pressure, the liquid working medium cannot enter the pole piece assembly 10 through the gap between the rotating cover 11 and the sealing seat 9, which ensures the continuous and reliable operation of the device. The rotating cover 11 and the shaft sleeve 2 are fixed and kept synchronous rotation by connecting screws, and are axially sealed by O-shaped sealing ring 5. The O-shaped sealing ring 5 also rotates and keeps relatively static. The service life of the static seal is longer, and even under the conditions of pressure in the crystallization kettle and gravity of the liquid working medium, the liquid working medium cannot pass through the O-shaped sealing ring 5.

[0043] Embodiment Bottom stirring reaction kettle crystallizer.

[0044] On-site test in a company in Shandong: Liquid medium: sodium nitrate mother liquor, temperature: 50-80℃. Pressure: slightly negative pressure, magnetic fluid seal has been running since March 11, 2025. All is normal, which ensures the long-term stable operation of the device.

[0045] Reference: [1]. Wang Hujun, He Xinzh, Zhang Yanjuan. Experimental study on the life of gas-proof magnetic fluid water seal [J]. Vacuum science and technology, 2020, 40 (12): 1197-1201. DOI: 10.13922 / j.cnki.cjovst.2020.12.14. [2] Qian Jiguo. Research on the stability of dynamic interface in magnetic fluid sealing liquid [D]. China University of Mining, 2009. [3] Wang Yuan, Fan Yuguang. Influence of relative velocity on interface stability in magnetic fluid liquid dynamic seal [J]. Fluid machinery, 2007, (01): 18-20. It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. Vertical bottom-entry liquid medium magnetic liquid seal, characterized by: It includes a rotating cover, which is in an inverted U shape and is buckled on the sleeve and fastened to the sleeve by connecting screws. A part of the sealing seat is installed in the rotating cover, and a bearing and a pole shoe assembly are installed between the sleeve and the sealing seat. The pole shoe assembly contains magnetic liquid for sealing the bearing. The other part of the sealing seat has an air inlet, and the sealing seat has an air channel. The air channel is connected to the gap between the top of the sealing seat and the rotating cover. Gas is introduced into the air inlet to prevent the liquid working medium from entering the pole shoe assembly. The axial contact position between the rotating cover and the sealing seat is provided with a spiral groove to prevent impurities from entering.

2. The vertical bottom-entry liquid medium magnetic liquid seal according to claim 1 is characterized in that the sealing seat is fastened to the cover plate by screws.

3. The vertical bottom-entry liquid medium magnetic liquid seal according to claim 1, characterized in that: An elastic circlip for the shaft is installed on the shaft sleeve for positioning the lower part of the bearing. The upper part of the bearing is positioned and fixed by the protrusion of the shaft sleeve and the sealing seat. The lower part of the pole shoe assembly is positioned by the protrusion of the shaft sleeve and the sealing seat. An isolation seal is installed on the upper part of the pole shoe assembly. An elastic circlip is installed on the hole of the sealing seat on the upper part of the isolation seal for positioning the upper part of the pole shoe assembly.

4. The vertical bottom-entry liquid medium magnetic liquid seal according to claim 1, characterized in that: O-rings are installed axially between the rotating cover and the shaft sleeve for axial sealing.

5. The vertical bottom-entry liquid medium magnetic liquid seal according to claim 1, characterized in that: The shaft sleeve is fixed to the vertical shaft through the driving sleeve at the bottom.

6. The vertical bottom-entry liquid medium magnetic liquid seal according to claim 1, characterized in that: The pole shoe assembly includes a spacer, a permanent magnet, a magnetic pole shoe and an O-ring. The magnetic pole shoe is divided into three parts: upper, middle and lower. The magnetic pole shoe has a rectangular tooth shape on the side facing the sleeve, and has a groove on the side facing the sealing seat for installing the O-ring. Spacers and permanent magnets are installed between the upper magnetic pole shoe and the middle magnetic pole shoe, and between the middle magnetic pole shoe and the lower magnetic pole shoe.

7. The vertical bottom-entry liquid medium magnetic liquid seal according to claim 1, characterized in that: A check valve is installed on the airway to prevent gas from flowing back.

8. The working method of vertical bottom-entry liquid medium magnetic liquid seal is characterized in that: It includes installing and positioning the components on the vertical shaft, introducing N2 into the air duct through the air inlet of the sealing seat, starting the equipment to rotate the vertical shaft, and preventing the liquid working fluid from entering the pole shoe assembly through the gap between the rotating cover and the sealing seat due to the existence of gas pressure.

9. The method according to claim 8, characterized in that When N2 is introduced intermittently, the liquid medium level is at the bottom of the rotating cover. Due to the gravity of the rotating cover, the N2 introduced into the sealing seat and in the gap between the rotating cover and the sealing seat when installed will be compressed to reach a balanced state. The compressed gas is discharged from the rotating cover through the spiral groove into the equipment.

10. The method according to claim 8, characterized in that When N2 is continuously introduced, the outside and top of the rotating cover are in contact with the liquid medium. Due to the gravity of the rotating cover and the liquid medium, the N2 introduced into the gap between the rotating cover and the sealing seat when installed will reach a new equilibrium state.

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