Magnetic fluid seal structure for liquid ring vacuum pump

Abstract

The present invention provides a magnetic fluid sealing structure for a liquid ring vacuum pump, comprising: a connecting flange, a non-magnetic sealing body, a first and a second sealing member, a magnetic fluid sealing assembly and a shaft sleeve; wherein the connecting flange is fixedly mounted on the end of the liquid ring vacuum pump and the flange hole is aligned with the shaft inlet; the outer ring surface of the non-magnetic sealing body has a mounting portion, a through hole in the axial middle portion, and the inner ring surface forms a first sealing cavity and a sealing assembly mounting cavity, and the first sealing member is installed in the first sealing cavity; the magnetic fluid sealing assembly is fixedly mounted in the sealing assembly mounting cavity and has a through hole in the axial middle portion, the non-magnetic sealing body is mounted on the connecting flange through the mounting portion, and a second sealing cavity is formed between the magnetic fluid sealing assembly and the connecting flange, and a second sealing member is installed therein; the shaft sleeve is sleeved on the pump shaft and penetrates the through hole, the through hole, the flange hole and the shaft inlet to be combined with the impeller in the liquid ring vacuum pump. In this way, the operation cycle of the magnetic fluid sealing structure can be increased, making the magnetic fluid sealing structure more economical and environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic fluid sealing, and in particular relates to a magnetic fluid sealing structure for a liquid ring vacuum pump. Background Art

[0002] Liquid ring vacuum pump is the core equipment to ensure the vacuum degree of tower equipment in chemical process. In chemical production, there are many gas components in the tower equipment. During the production process, neither the outside air is allowed to enter the tower equipment nor the gas in the tower equipment is allowed to leak into the atmosphere. In the normal operation of the liquid ring vacuum pump, the pump cavity is gas-liquid two-phase, of which the outer ring in the pump cavity is the liquid ring, and the inner ring in the pump cavity is the gas component. The seal at the shaft inlet of the liquid ring vacuum pump is to prevent the gas components in the pump cavity from leaking to the outside.

[0003] At present, magnetic liquid sealing technology is widely used in the field of vacuum and gas sealing. In the production process, it can achieve zero leakage for the sealing of toxic, harmful, flammable and explosive gases. However, it is rarely used in chemical production, especially in the sealing technology of liquid ring vacuum pumps. The sealing of traditional liquid ring vacuum pumps usually adopts single or double end mechanical seals. The mechanical seals need to be equipped with sealing liquid systems and cooling circulation systems. The sealing liquid system often has leakage problems during use, which affects the quality of the product and pollutes the environment. In addition, the sealing liquid system and the cooling circulation system will also increase the operating costs during continuous operation. Therefore, in the current environment where the country is increasingly strict with the control of volatile organic compound pollution, how to ensure zero leakage of liquid ring vacuum pumps during operation has become one of the important issues that need to be solved urgently. Summary of the invention

[0004] The technical problem to be solved by this technical solution is how to provide a sealing structure of a liquid ring vacuum pump to solve the leakage problem of the mechanical sealing structure, and to increase the operating cycle of the liquid ring vacuum pump while reducing the operating cost, thereby creating better economic and environmental benefits.

[0005] In order to solve the above technical problems, the present technical scheme provides a magnetic fluid sealing structure for a liquid ring vacuum pump, which comprises: a connecting flange, a non-magnetic sealing body, a first sealing member, a magnetic fluid sealing assembly, a second sealing member and a sleeve; wherein the connecting flange is mounted and fixed to the end of the liquid ring vacuum pump, and the flange hole of the connecting flange is aligned with the shaft inlet of the liquid ring vacuum pump; the non-magnetic sealing body is an annular body and its outer ring surface protrudes outward to form an annular mounting portion, its axial middle portion has a through hole, and its inner ring surface is recessed inward to respectively form an annular first sealing cavity and a sealing assembly mounting cavity, the first sealing cavity is located on the side away from the connecting flange and its diameter is smaller than the diameter of the sealing assembly mounting cavity, and the first sealing cavity is mounted with a first sealing member; the magnetic fluid sealing assembly is annular The magnetic fluid sealing component is installed and fixed in the sealing component installation cavity, and the through hole is coaxial with the through hole; the through hole is aligned with the flange hole, and bolts are passed through the installation portion and screwed into the corresponding screw holes on the connecting flange to fix the non-magnetic sealing body on the side of the connecting flange opposite to the liquid ring vacuum pump, and an annular second sealing cavity is formed between the magnetic fluid sealing component in the sealing component installation cavity and the connecting flange, and a second sealing member is installed in the second sealing cavity; the shaft sleeve is cylindrical and sleeved and fixed on the pump shaft, and the shaft sleeve is sequentially penetrated with a through hole, a through hole, a flange hole and a shaft inlet to be combined with an impeller in the liquid ring vacuum pump, and the shaft sleeve can rotate circumferentially relative to the non-magnetic sealing body, the magnetic fluid sealing component and the connecting flange along with the driven pump shaft. Accordingly, the magnetic fluid sealing assembly can effectively improve the sealing performance of the shaft end of the liquid ring vacuum pump, and the first sealing member on one side of the magnetic fluid sealing assembly can effectively prevent the magnetic fluid in the magnetic fluid sealing assembly from leaking outward, and can also prevent the outside air from interfering with the magnetic fluid; the second sealing member on the other side of the magnetic fluid sealing assembly is an additional sealing structure added between the magnetic fluid sealing assembly and the shaft inlet, which can effectively improve the sealing performance of the entire sealing structure, and can effectively prevent the gas components leaked from the liquid ring vacuum pump from interfering with the magnetic fluid in the magnetic fluid sealing assembly, thereby increasing the operating cycle of the magnetic fluid sealing structure and making the magnetic fluid sealing structure more economical and environmentally friendly.

[0006] As another implementation of the technical solution, the magnetic fluid sealing assembly is mainly composed of three annular pole shoes arranged side by side, and two annular permanent magnets; the two permanent magnets are respectively arranged between the three pole shoes; the pole shoe has several annular grooves opened along the circumferential direction on its inner ring surface, and the annular grooves are filled with magnetic fluid so that the permanent magnets, pole shoes and sleeves form a magnetic circuit.

[0007] As another implementation of the present technical solution, the outer annular surfaces of the three pole shoes are all provided with a liquid replenishment ring groove along the circumferential direction, and concave annular grooves are respectively provided on both sides of the liquid replenishment ring groove along the circumferential direction, and a number of liquid replenishment flow channels in the pole shoes are evenly provided in the liquid replenishment ring groove, which pass through the annular groove corresponding to the position of the liquid replenishment ring groove, and the direction of the liquid replenishment flow channel in the pole shoe is the same as the radial direction of the pole shoe, and an O-ring is arranged in the concave annular groove; a liquid replenishment flow channel communicating with the liquid replenishment ring groove of each pole shoe is arranged in the upper part of the non-magnetic sealing body, and a magnetic fluid injection port communicating with the liquid replenishment flow channel is arranged on the outer annular surface of the upper part of the non-magnetic sealing body; a leakage detection flow channel communicating with the side of the sealing component mounting cavity away from the connecting flange is arranged in the lower part of the non-magnetic sealing body, and a leakage detection port communicating with the leakage detection flow channel is arranged on the outer annular surface of the lower part of the non-magnetic sealing body. Accordingly, it can be known whether magnetic fluid needs to be added to the non-magnetic sealing body by detecting the leak detection port, and the magnetic fluid can be added to the non-magnetic sealing body in time through the magnetic fluid injection port; and the added magnetic fluid can be injected into the liquid replenishment ring grooves on the outer ring surface of each pole shoe through the liquid replenishment flow channel, and injected into the ring groove along the liquid replenishment ring groove and the liquid replenishment flow channel in the pole shoe, and injected into other ring grooves through the gap between the groove teeth between each ring groove and the outer side surface of the shaft sleeve; and the O-ring set in the concave ring groove on the outer ring surface of each pole shoe can effectively prevent crosstalk between the magnetic fluids injected into each liquid replenishment ring groove.

[0008] As another implementation of the technical solution, an annular cooling water chamber is arranged around the outside of the sealing assembly installation cavity inside the non-magnetic sealing body, and a cooling water inlet communicating with the annular cooling water chamber is opened on the outer ring surface of the upper part of the non-magnetic sealing body, and a cooling water outlet communicating with the annular cooling water chamber is opened on the outer ring surface of the lower part of the non-magnetic sealing body. In this way, the heat generated by the non-magnetic sealing body during the operation of the liquid ring vacuum pump can be effectively removed to improve the stability of the magnetic fluid sealing structure and increase the operation cycle of the magnetic fluid sealing structure.

[0009] As another implementation of the technical solution, the first seal is a medium separation annular force seal, and the two sealing lips of the first seal are respectively facing in opposite directions and attached to the outer side of the sleeve. In this way, the magnetic fluid inside the non-magnetic sealing body can be effectively prevented from leaking to the outside, and the interference of the outside air on the magnetic fluid can be prevented.

[0010] As another implementation of the technical solution, the magnetic fluid sealing structure for the liquid ring vacuum pump also includes: a positioning screw sleeve; the positioning screw sleeve is annular and has an external thread on its outer ring surface, and an internal thread is provided on the wall surface of the chamber of the sealing component installation cavity close to the connecting flange corresponding to the external thread, and the positioning screw sleeve is arranged on the side of the sealing component installation cavity close to the connecting flange through the screw engagement of the external thread and the internal thread, and the magnetic fluid sealing component is fixed between the first sealing cavity and the positioning screw sleeve; a second sealing cavity is formed between the positioning screw sleeve and the connecting flange. In this way, the installation and fixation of the magnetic fluid sealing component can be facilitated.

[0011] As another implementation of the present technical solution, the second sealing cavity is an annular cavity formed by the corresponding positions of the positioning screw sleeve and the connecting flange being recessed in opposite directions and enclosing the outer side surface of the sleeve; the second sealing member is composed of a medium-separated annular force seal arranged in the recessed space of the connecting flange and a standard annular force seal arranged in the recessed space of the positioning screw sleeve, and the sealing lips of the standard annular force seal and one of the sealing lips of the medium-separated annular force seal are arranged facing each other and are both in contact with the outer side surface of the sleeve to enclose an annular isolation air cavity; an air inlet duct communicating with the isolation air cavity is provided in the upper part of the non-magnetic sealing body, and an air inlet port communicating with the air inlet duct is opened on the outer ring surface of the upper part of the non-magnetic sealing body; an exhaust duct communicating with the isolation air cavity is provided in the lower part of the non-magnetic sealing body, and an exhaust port communicating with the exhaust duct is opened on the outer ring surface of the lower part of the non-magnetic sealing body. Accordingly, inert gas can be circulated into the isolation air cavity to achieve effective isolation of the magnetic fluid and the sealed medium. Even if some gas components leak out from the shaft end of the liquid ring vacuum pump, they will be blocked by a sealing lip of the medium separation annular force seal. Even if a small amount of gas components enter the isolation air cavity, they will be diluted by the inert gas and discharged by the isolation gas circulation system, thereby effectively preventing the magnetic fluid from being contaminated and emulsified and failing.

[0012] As another implementation of the technical solution, the magnetic fluid sealing structure for the liquid ring vacuum pump also includes: a positioning ring; there is a spacing between the inner ring surface of the end side of the non-magnetic sealing body away from the connecting flange and the outer side surface of the sleeve, and the spacing is reduced along the direction from the end side to the first sealing cavity to form a conical ring cavity; the positioning ring has a mounting section and a positioning section that are annular and connected to each other, and the mounting section is fixed to the end side by bolts, so that the positioning section is inserted and fixed in the conical ring cavity, and the inner ring surface of the positioning section fits the outer side surface of the sleeve, so that the outer ring surface of the positioning section is inclined and connected to the inner ring surface of the end side corresponding to the reduced spacing. In this way, the radial positioning of the non-magnetic sealing body relative to the sleeve can be assisted to improve the operating stability of the magnetic fluid sealing structure for the liquid ring vacuum pump.

[0013] As another implementation of the present technical solution, the magnetic fluid sealing structure for the liquid ring vacuum pump also includes: an expansion sleeve assembly installed on the shaft sleeve; the sleeve wall thickness of the installation portion of the expansion sleeve assembly on the shaft sleeve is smaller than the sleeve wall thickness of other portions of the shaft sleeve, and a number of expansion grooves penetrating the sleeve wall are evenly opened along the circumferential direction at the installation portion, and the direction of the expansion grooves is the same as the axial direction of the shaft sleeve; the expansion sleeve assembly is composed of an annular expansion sleeve upper hoop and an expansion sleeve lower hoop, and an expansion bolt; wherein the expansion sleeve lower hoop has an annular fitting end and an expansion end connected to each other, the fitting end is sleeved on one side of the installation portion adjacent to the non-magnetic sealing body, and the inner ring of the expansion end There is a spacing between the surface and the outer side surface of the installation part, and the spacing gradually increases along the direction opposite to the non-magnetic sealing body to form a tightening ring cavity; the upper hoop of the expansion sleeve has a mounting end and an insertion end which are annular and connected to each other, and the mounting end is installed on the fitting end through a tightening bolt, so that the insertion end is inserted into the expansion ring cavity, and the inner ring surface of the insertion end is fitted to the outer side surface of the installation part, so that the outer ring surface of the insertion end is inclined corresponding to the gradually increasing spacing and is engaged with the inner ring surface of the expansion end; by screwing the tightening bolt, the insertion end of the upper hoop of the expansion sleeve is pressed into the expansion ring cavity of the lower hoop of the expansion sleeve and the mounting part is pressed to deform the expansion groove, so that the shaft sleeve is aligned and fastened to the pump shaft.

[0014] As another implementation of the technical solution, an annular step groove is provided between the joint surface of the connecting flange and the non-magnetic sealing body, and an O-type sealing ring is arranged in the annular step groove, thereby ensuring the sealing performance between the joint surface of the connecting flange and the non-magnetic sealing body. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a specific embodiment of a magnetic fluid sealing structure for a liquid ring vacuum pump of the present invention.

[0016] Figure 2 It is a side partial cross-sectional view of the non-magnetic conductive seal body in the present invention.

[0017] Figure 3 It is a side partial cross-sectional view of the magnetic fluid sealing assembly in the present invention.

[0018] Explanation of symbols in the accompanying drawings:

[0019] 1 Magnetic fluid sealing structure for liquid ring vacuum pump; 2 connecting flange; 21 flange hole; 3 non-magnetic sealing body; 31 installation part; 32 through hole; 33 first sealing chamber; 34 sealing assembly installation chamber; 35 second sealing chamber; 36 annular step groove; 371 liquid replenishing channel; 372 magnetic fluid injection port; 373 leak detection channel; 374 leak detection port; 381 air inlet; 382 air inlet; 383 exhaust channel; 384 exhaust port; 39 positioning screw sleeve; 4 first sealing element; 5 magnetic fluid sealing assembly; 51 through hole; 52 pole shoe; 53 permanent magnet; 54 ring groove; 55 liquid replenishing ring groove; 56 inner concave ring groove; 57 liquid replenishing channel in pole shoe; 58 groove tooth; 6 second sealing element; 61 isolation air chamber; 7 sleeve; 71 expansion groove; 72 expansion sleeve upper hoop; 721 Installation end; 722 Insertion end; 73 Lower hoop of expansion sleeve; 731 Fitting end; 732 Expansion end; 74 Expansion bolt; 8 Positioning ring; 81 Installation section; 82 Positioning section; 9 Annular cooling water chamber; 91 Cooling water inlet; 92 Cooling water outlet. DETAILED DESCRIPTION

[0020] The detailed description and technical contents of the present invention are described as follows with reference to the accompanying drawings. However, the accompanying drawings are only provided for reference and description and are not intended to limit the present invention.

[0021] like Figure 1 As shown, a specific embodiment of the magnetic fluid sealing structure for a liquid ring vacuum pump of the present invention. The magnetic fluid sealing structure 1 for a liquid ring vacuum pump comprises: a connecting flange 2, a non-magnetic sealing body 3, a first sealing member 4, a magnetic fluid sealing assembly 5, a second sealing member 6 and a sleeve 7. Among them, the connecting flange 2 is mounted and fixed to the end of the liquid ring vacuum pump (not shown in the figure), and the flange hole 21 of the connecting flange 2 is aligned with the shaft inlet of the liquid ring vacuum pump. The non-magnetic sealing body 3 is an annular body component made of non-magnetic material, and its outer ring surface protrudes outward to form an annular mounting portion 31, and a plurality of through holes (not shown in the figure) are opened on the mounting portion 31 for installation and fixation with the connecting flange 2. The non-magnetic sealing body 3 has a through hole 32 in the axial middle part. Combined with Figure 2As shown, the inner ring surface of the non-magnetic sealing body 3 is recessed inward to form an annular first sealing cavity 33 and a sealing assembly installation cavity 34. The first sealing cavity 33 is located on the side away from the connecting flange 2 and its diameter is smaller than the diameter of the sealing assembly installation cavity 34. The first sealing component 4 is installed in the first sealing cavity 33. The magnetic fluid sealing component 5 is an annular body and has a through hole 51 in the axial middle part. The magnetic fluid sealing component 5 is installed and fixed in the sealing component installation cavity 34 and the through hole 51 is coaxial with the through hole 32. The through hole 32 is aligned with the flange hole 21, and the bolts are passed through the through holes on the installation part 31 and screwed into the corresponding screw holes on the connecting flange 2 to fix the non-magnetic sealing body 3 on the side of the connecting flange 2 opposite to the liquid ring vacuum pump, and an annular second sealing cavity 35 is formed between the magnetic fluid sealing component 5 in the sealing component installation cavity 34 and the connecting flange 2, and the second sealing component 6 is installed in the second sealing cavity 35. An annular step groove 36 may be provided between the joint surfaces of the connecting flange 2 and the non-magnetic sealing body 3, and an O-ring is provided in the annular step groove 36, so as to ensure the sealing performance between the joint surfaces of the connecting flange 2 and the non-magnetic sealing body 3. The shaft sleeve 7 is cylindrical and is sleeved and fixed on the pump shaft (not shown in the figure). The shaft sleeve 7 is sequentially penetrated with a through hole 32, a through hole 51, a flange hole 21 and a shaft inlet to be combined with an impeller (not shown in the figure) in the liquid ring vacuum pump, and the shaft sleeve 7 can rotate circumferentially relative to the non-magnetic sealing body 3, the magnetic fluid sealing assembly 5 and the connecting flange 2 along with the driven pump shaft.

[0022] More specifically, combined with Figure 3 As shown, the magnetic fluid sealing assembly 5 is mainly composed of three pole shoes 52 that are annular and arranged side by side, and two permanent magnets 53 that are annular; wherein the two permanent magnets 53 are respectively arranged between the three pole shoes 52; the pole shoe 52 is provided with several annular grooves 54 along the circumferential direction on its inner annular surface, and the annular grooves 54 are filled with magnetic fluid so that the permanent magnets 53, the pole shoes 52 and the shaft sleeve 7 form a magnetic circuit. The outer annular surfaces of the three pole shoes 52 are provided with a liquid replenishing annular groove 55 along the circumferential direction, and concave annular grooves 56 are provided along the circumferential direction on both sides of the liquid replenishing annular groove 55. The liquid replenishing annular groove 55 is evenly provided with several pole shoe in-liquid replenishing flow channels 57 that penetrate to the annular groove 54 corresponding to the position of the liquid replenishing annular groove 55, and the direction of the pole shoe in-liquid replenishing flow channel 57 is the same as the radial direction of the pole shoe 52, and an O-ring is provided in the concave annular groove 56. Figure 2As shown, a liquid replenishment channel 371 communicating with the liquid replenishment ring groove 55 of each pole shoe 52 is provided in the upper part of the non-magnetic sealing body 3, and a magnetic fluid injection port 372 communicating with the liquid replenishment channel 371 is provided on the outer ring surface of the upper part of the non-magnetic sealing body 3. A leakage detection channel 373 communicating with the side of the sealing component installation cavity 34 away from the connecting flange 2 is provided in the lower part of the non-magnetic sealing body 3, and a leakage detection port 374 communicating with the leakage detection channel 373 is provided on the outer ring surface of the lower part of the non-magnetic sealing body 3. The leakage detection port 374 can be externally connected to a gas alarm (not shown) or other detection equipment. Accordingly, the gas alarm can detect the leak detection port 374 to know whether the non-magnetic seal 3 needs to be filled with magnetic fluid, and the magnetic fluid can be timely filled into the non-magnetic seal 3 through the magnetic fluid injection port 372, without stopping the operation of the magnetic fluid sealing structure and disassembling the non-magnetic seal 3 and the magnetic fluid sealing assembly 5, and the filled magnetic fluid can be respectively injected into the replenishment ring groove 55 on the outer ring surface of each pole shoe 52 through the replenishment flow channel 371, and injected into the ring groove 54 along the replenishment ring groove 55 and the replenishment flow channel 57 in the pole shoe, and injected into other ring grooves 54 through the gap between the groove teeth 58 between each ring groove 54 and the outer side surface of the shaft sleeve 7. The O-ring provided in the concave ring groove 56 on the outer ring surface of each pole shoe 52 is in contact with the wall surface of the sealing assembly installation cavity 34 and deformed, so as to effectively prevent the crosstalk between the magnetic fluids injected into each replenishment ring groove 55.

[0023] like Figure 1As shown, in this embodiment, the first seal 4 is a medium separation type annular force seal, and its two sealing lips are respectively facing opposite directions and attached to the outer side of the sleeve 7, so as to effectively prevent the magnetic fluid inside the non-magnetic sealing body 3 from leaking to the outside, and prevent the interference of the outside air on the magnetic fluid. The magnetic fluid sealing structure 1 for the liquid ring vacuum pump can also include: a positioning screw sleeve 39, which is annular and has an external thread on its outer ring surface, and the sealing component installation cavity 34 is provided with an internal thread on the wall surface of the chamber corresponding to the external thread near the connecting flange 2, and the positioning screw sleeve 39 is installed on the side of the sealing component installation cavity 34 near the connecting flange 2 through the screwing of the external thread and the internal thread, and the magnetic fluid sealing component 5 is fixed between the first sealing cavity 33 and the positioning screw sleeve 39, and the second sealing cavity 35 is formed between the positioning screw sleeve 39 and the connecting flange 2, so as to facilitate the installation and fixation of the magnetic fluid sealing component 5. In more detail, the second sealing cavity 35 is an annular cavity formed by the corresponding positions of the positioning screw sleeve 39 and the connecting flange 2 being recessed in opposite directions and enclosed with the outer side surface of the shaft sleeve 7. The second sealing member 6 is composed of a medium separation type annular force seal arranged in the recessed space of the connecting flange 2 and a standard type annular force seal arranged in the recessed space of the positioning screw sleeve 39, and the sealing lips of the standard type annular force seal and one of the sealing lips of the medium separation type annular force seal are mutually The non-magnetic sealing body 3 is arranged opposite to each other and is in contact with the outer side surface of the shaft sleeve 7 to enclose an annular isolation air cavity 61; an air inlet 381 communicating with the isolation air cavity 61 is provided in the upper part of the non-magnetic sealing body 3, and an air inlet port 382 communicating with the air inlet 381 is opened on the outer ring surface of the upper part of the non-magnetic sealing body 3; an exhaust duct 383 communicating with the isolation air cavity 61 is provided in the lower part of the non-magnetic sealing body 3, and an exhaust port 384 communicating with the exhaust duct 383 is opened on the outer ring surface of the lower part of the non-magnetic sealing body 3, as shown in FIG. Figure 1As shown, the air inlet 382 and the exhaust port 384 can also be opened on the mounting portion 31. Accordingly, an inert gas with a pressure less than 0.1 Mpa can be circulated into the isolation air chamber 61 to effectively isolate the magnetic fluid from the sealed medium. Even if some gas components leak from the shaft end of the liquid ring vacuum pump, they will be blocked by a sealing lip of the medium-separating ring-shaped universal force seal. Even if a small amount of gas components enter the isolation air chamber, they will be diluted by the inert gas and excluded by the isolation air circulation system, thereby effectively preventing the magnetic fluid from being contaminated and emulsified and failing. The isolation air circulation system can introduce nitrogen with a pressure of P1 into the air inlet, and P1 < P - 5 Kpa, where P is the pressure of the exhaust port. The inert gas forms an air seal ring after entering the isolation air chamber, thereby ensuring that the magnetic fluid does not contact the sealed medium. Under the pressure difference of the above-mentioned inert gas, the external inert gas does not interfere with the original working condition, and the trace medium gas will be diluted after entering the isolation air chamber and enter the recovery system through the exhaust port without polluting the environment. In the present invention, both the standard ring-shaped universal force seal and the medium-separating ring-shaped universal force seal applied can be selected as Tecan universal force seals, which can achieve a circumferential linear velocity of 90 m / s and can withstand a pressure of 0.5 Mpa at the same time; however, products of other brands can also be selected.

[0024] As Figure 1 shown, in this embodiment, the magnetic fluid seal structure 1 for the liquid ring vacuum pump may further include: a positioning ring 8. There is a gap between the inner ring surface of the non-magnetic sealing body 3 on the end side far from the connecting flange 2 and the outer side surface of the shaft sleeve 7, and this gap decreases along the direction from this end side to the first sealing cavity 33 to form a tapered ring cavity. The positioning ring 8 has an installation section 81 and a positioning section 82 that are annular and connected to each other. The installation section 81 is fixedly installed on this end side by bolts, so that the positioning section 82 is inserted and fixed in the tapered ring cavity, and the inner ring surface of the positioning section 82 fits the outer side surface of the shaft sleeve 7, and the outer ring surface of the positioning section 82 is inclined corresponding to the decreasing gap and engages with the inner ring surface of this end side, thereby assisting in the radial positioning of the non-magnetic sealing body 3 relative to the shaft sleeve 7 to improve the operating stability of the magnetic fluid seal structure 1 for the liquid ring vacuum pump.

[0025] In another embodiment of the present invention, an annular cooling water chamber 9 can be disposed around the outside of the non-magnetic sealing body 3 inside the sealing component installation cavity 34. A cooling water inlet 91 communicating with the annular cooling water chamber 9 is opened on the outer ring surface of the upper part of the non-magnetic sealing body 3, and a cooling water outlet 92 communicating with the annular cooling water chamber 9 is opened on the outer ring surface of the lower part of the non-magnetic sealing body 3, thereby effectively removing the heat generated by the non-magnetic sealing body 3 during the operation of the liquid ring vacuum pump, improving the stability of the magnetic fluid seal structure, and increasing the operating cycle of the magnetic fluid seal structure.

[0026] In another embodiment of the present invention, the magnetic fluid sealing structure 1 for the liquid ring vacuum pump may further include: a clamping sleeve assembly installed on the shaft sleeve 7, and the sleeve wall thickness of the installation portion of the clamping sleeve assembly on the shaft sleeve 7 is less than the sleeve wall thickness of other portions of the shaft sleeve, and a plurality of clamping grooves 71 penetrating the sleeve wall of the shaft sleeve 7 are uniformly opened along the circumferential direction at the installation portion, and the direction of the clamping grooves 71 is the same as the axial direction of the shaft sleeve 7; the clamping sleeve assembly is composed of an annular clamping sleeve upper hoop 72 and a clamping sleeve lower hoop 73, and a clamping bolt 74; wherein the clamping sleeve lower hoop 73 has an annular fitting end 731 and a clamping end 732 connected to each other, the fitting end 731 is sleeved on one side of the installation portion adjacent to the non-magnetic sealing body 3, and the inner ring surface of the clamping end 732 is aligned with the installation portion. There is a spacing between the outer sides, and the spacing gradually increases in the direction opposite to the non-magnetic sealing body 3 to form a tightening ring cavity; the upper hoop 72 of the expansion sleeve has a mounting end 721 and an insertion end 722 that are annular and connected to each other, and the mounting end 721 is installed on the fitting end 731 through a tightening bolt 74, so that the insertion end 722 is inserted into the expansion ring cavity, and the inner ring surface of the insertion end 722 is fitted to the outer side surface of the mounting position, so that the outer ring surface of the insertion end 722 is inclined corresponding to the gradually increasing spacing and is engaged with the inner ring surface of the expansion end 732; by screwing the tightening bolt 74, the insertion end 722 of the upper hoop 72 of the expansion sleeve is pressed into the expansion ring cavity of the lower hoop 73 of the expansion sleeve and the mounting position is pressed to deform the expansion groove 71, so that the shaft sleeve 7 is aligned and fastened to the pump shaft.

[0027] In summary, the magnetic fluid sealing assembly in the present invention can effectively improve the sealing performance of the shaft end of the liquid ring vacuum pump, and the first sealing member on one side of the magnetic fluid sealing assembly can effectively prevent the magnetic fluid in the magnetic fluid sealing assembly from leaking outward, and can also prevent the interference of the outside air on the magnetic fluid. The second sealing member on the other side of the magnetic fluid sealing assembly is an additional sealing structure added between the magnetic fluid sealing assembly and the shaft end of the liquid ring vacuum pump, which can effectively improve the sealing performance of the entire sealing structure, and can effectively prevent the gas components leaked from the liquid ring vacuum pump from interfering with the magnetic fluid in the magnetic fluid sealing assembly, thereby increasing the operating cycle of the magnetic fluid sealing structure, making the magnetic fluid sealing structure more economical and environmentally friendly.

[0028] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Other equivalent changes made using the patent concept of the present invention should all fall within the patent protection scope of the present invention.

Claims

1. A magnetic fluid sealing structure for a liquid ring vacuum pump, characterized in that: include: A connecting flange, a non-magnetic sealing body, a first sealing component, a magnetic fluid sealing assembly, a second sealing component and a sleeve; the connecting flange is mounted and fixed to the end of the liquid ring vacuum pump, and the flange hole of the connecting flange is aligned with the shaft inlet of the liquid ring vacuum pump; the non-magnetic sealing body is an annular body and its outer ring surface protrudes outward to form an annular mounting portion, its axial middle part has a through hole, and its inner ring surface is recessed inward to form an annular first sealing cavity and a sealing assembly mounting cavity, respectively, the first sealing cavity is located on the side away from the connecting flange and its diameter is smaller than the diameter of the sealing assembly mounting cavity, and the first sealing component is mounted in the first sealing cavity; the magnetic fluid sealing The sealing assembly is an annular body and has a through hole in its axial middle part. The magnetic fluid sealing assembly is installed and fixed in the sealing assembly installation cavity and the through hole is coaxial with the through hole; the through hole is aligned with the flange hole, and the bolts are passed through the installation part and screwed into the corresponding screw holes on the connecting flange to fix the non-magnetic sealing body on the side of the connecting flange opposite to the liquid ring vacuum pump, and an annular second sealing cavity is formed between the magnetic fluid sealing assembly in the sealing assembly installation cavity and the connecting flange, and the second sealing member is installed in the second sealing cavity; the sleeve is cylindrical and is sleeved and fixed on the pump shaft, and the sleeve is passed through the The through hole, through hole, flange hole and shaft inlet are combined with the impeller in the liquid ring vacuum pump, and the sleeve can rotate circumferentially relative to the non-magnetic sealing body, the magnetic fluid sealing assembly and the connecting flange along with the driven pump shaft; the magnetic fluid sealing assembly is mainly composed of three pole shoes in annular shape and arranged side by side, and two permanent magnets in annular shape; the two permanent magnets are respectively arranged between the three pole shoes; the pole shoes are provided with several annular grooves along the circumferential direction on the inner annular surface, and the annular grooves are filled with magnetic fluid so that the permanent magnets, pole shoes and sleeves form a magnetic circuit; the outer annular surfaces of the three pole shoes are provided with liquid replenishment ring grooves along the circumferential direction, and the liquid replenishment ring grooves are provided in the replenishment ring grooves. Concave ring grooves are respectively provided on both sides of the liquid ring groove, and several pole shoe in-liquid replenishment channels that penetrate into the ring groove corresponding to the position of the liquid replenishment ring groove are evenly provided in the liquid replenishment ring groove, and an O-ring is arranged in the concave ring groove; a liquid replenishment channel communicating with the liquid replenishment ring groove of each pole shoe is provided in the upper part of the non-magnetic sealing body, and a magnetic fluid injection port communicating with the liquid replenishment channel is provided on the outer ring surface of the upper part of the non-magnetic sealing body; a leakage detection channel communicating with the side of the sealing component installation cavity away from the connecting flange is provided in the lower part of the non-magnetic sealing body, and a leakage detection port communicating with the leakage detection channel is provided on the outer ring surface of the lower part of the non-magnetic sealing body.

2. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 1, characterized in that: An annular cooling water chamber is arranged inside the non-magnetic seal body around the outside of the sealing component installation cavity, and a cooling water inlet connected to the annular cooling water chamber is opened on the outer ring surface of the upper part of the non-magnetic seal body, and a cooling water outlet connected to the annular cooling water chamber is opened on the outer ring surface of the lower part of the non-magnetic seal body.

3. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 1, characterized in that: The first seal is a medium separation annular force seal, and two sealing lips of the first seal are respectively arranged in opposite directions and attached to the outer side surface of the sleeve.

4. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 1, characterized in that: Also includes: Positioning screw sleeve; the positioning screw sleeve is annular and has an external thread on its outer ring surface, and an internal thread is provided on the part of the chamber wall of the sealing component installation cavity close to the connecting flange corresponding to the external thread, and the positioning screw sleeve is arranged on the side of the sealing component installation cavity close to the connecting flange through the screwing of the external thread and the internal thread, and the magnetic fluid sealing component is pressed and fixed between the first sealing cavity and the positioning screw sleeve; the second sealing cavity is formed between the positioning screw sleeve and the connecting flange.

5. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 4, characterized in that: The second sealing cavity is an annular cavity formed by the corresponding positions of the positioning screw sleeve and the connecting flange being recessed in opposite directions and enclosing the outer side surface of the sleeve; the second sealing member is composed of a medium-separated annular force seal arranged in the recessed space of the connecting flange and a standard annular force seal arranged in the recessed space of the positioning screw sleeve, and the sealing lips of the standard annular force seal and one of the sealing lips of the medium-separated annular force seal are arranged facing each other and are both in contact with the outer side surface of the sleeve to enclose an annular isolation air cavity; an air inlet duct communicating with the isolation air cavity is provided in the upper part of the non-magnetic sealing body, and an air inlet port communicating with the air inlet duct is opened on the outer ring surface of the upper part of the non-magnetic sealing body; an exhaust duct communicating with the isolation air cavity is provided in the lower part of the non-magnetic sealing body, and an exhaust port communicating with the exhaust duct is opened on the outer ring surface of the lower part of the non-magnetic sealing body.

6. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 1, characterized in that: Also includes: Positioning ring; There is a spacing between the inner annular surface of the end side of the non-magnetic sealing body away from the connecting flange and the outer surface of the sleeve, and the spacing decreases along the direction from the end side to the first sealing cavity to form a conical annular cavity; the positioning ring has an annular mounting section and a positioning section that are connected to each other, and the mounting section is fixed to the end side by bolts, so that the positioning section is inserted and fixed in the conical annular cavity, and the inner annular surface of the positioning section is in contact with the outer surface of the sleeve, so that the outer annular surface of the positioning section is inclined corresponding to the reduced spacing and is engaged with the inner annular surface of the end side.

7. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 1, characterized in that: Also includes: A clamping sleeve assembly mounted on the shaft sleeve; the sleeve wall thickness of the mounting portion of the sleeve where the clamping sleeve assembly is mounted is smaller than the sleeve wall thickness of other portions of the sleeve, and a plurality of clamping grooves penetrating the sleeve wall are uniformly opened along the circumferential direction at the mounting portion, and the direction of the clamping grooves is the same as the axial direction of the sleeve; the clamping sleeve assembly is composed of an annular clamping sleeve upper hoop and an annular clamping sleeve lower hoop, and a clamping bolt; the clamping sleeve lower hoop has an annular fitting end and an expansion end connected to each other, the fitting end is sleeved on one side of the mounting portion adjacent to the non-magnetic sealing body, and there is a spacing between the inner annular surface of the expansion end and the outer side surface of the mounting portion, and the spacing is along The direction opposite to the non-magnetic sealing body gradually increases to form a tightening ring cavity; the upper hoop of the expansion sleeve has a mounting end and an insertion end that are annular and connected to each other, and the mounting end is installed on the fitting end through the expansion bolt, so that the insertion end is inserted into the expansion ring cavity, and the inner ring surface of the insertion end is fitted to the outer side surface of the mounting part, so that the outer ring surface of the insertion end is inclined corresponding to the gradually increasing distance and is engaged with the inner ring surface of the expansion end; by screwing the expansion bolt, the insertion end of the upper hoop of the expansion sleeve is pressed into the expansion ring cavity of the lower hoop of the expansion sleeve and the mounting part is pressed to deform the expansion groove, so that the sleeve is aligned and fastened to the pump shaft.

8. The magnetic fluid sealing structure for a liquid ring vacuum pump according to claim 1, characterized in that: An annular step groove is provided between the joint surface of the connecting flange and the non-magnetic conductive sealing body, and an O-type sealing ring is arranged in the annular step groove.

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