Magnetic fluid sealing device based on labyrinth tower and its sealing performance test bench

Abstract

The present invention belongs to the technical field of magnetic fluid sealing in mechanical engineering, and specifically relates to a magnetic fluid sealing device based on a labyrinth tower, which is applied to a main shaft and comprises a shell component and a magnetic fluid sealing component, wherein the shell component comprises a first sealing shell and an end cover; the magnetic fluid sealing component comprises a main shaft sleeve, a pole shoe group and a permanent magnet, and a labyrinth tower-shaped sealing structure is formed between the pole shoe group and the main shaft, which can still have a good sealing effect under the working conditions of large shaft diameter, high pressure and high speed; in addition, the present invention also provides a sealing performance test bench for a magnetic fluid sealing device based on a labyrinth tower, which uses a main shaft drive component to provide a rotation speed and torque to the main shaft, and a pressurizing component to provide a constant pressure to the sealing device, and is matched with a detection component to perform real-time testing on the sealing performance of the magnetic fluid sealing device under working conditions such as adjusting different rotation speeds and different pressures, which has important guiding significance for the design and optimization of the sealing gap structure.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic fluid sealing in mechanical engineering, and in particular relates to a magnetic fluid sealing device based on a labyrinth tower and a sealing performance test bench thereof. Background Art

[0002] Magnetic fluid seals use the magnetic field generated by permanent magnets or electromagnets to stably maintain the magnetic fluid between the rotating shaft and the housing, forming a "liquid O-ring" to form a contactless seal. Magnetic fluid seals have the characteristics of zero leakage, low friction and long life, and are widely used in vacuum, semiconductor processing, metallurgy and chemical industry and other fields.

[0003] However, with the development of sealing equipment towards intelligence, large-scale, high-speed and high-pressure, large gap, high-pressure and high-speed working conditions are often accompanied by large centrifugal force and heat accumulation, which will cause the performance of magnetic fluid sealing to decline rapidly, specifically manifested in the decline in the pressure resistance of the sealing structure, becoming the main problem restricting the further application and development of magnetic fluid sealing. Therefore, how to improve the sealing performance of magnetic fluid under large shaft diameter, high-speed and high-pressure working conditions has become one of the key points in the field of magnetic fluid sealing. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a magnetic fluid sealing device based on a labyrinth tower. The sealing gap adopts a special structure of the labyrinth tower, aiming to achieve reliable sealing of the gaseous medium under high pressure and high speed conditions for a large diameter main shaft through the coordinated sealing action of centrifugal force and magnetic fluid.

[0005] At the same time, the present invention also provides a sealing performance test bench used for a maze-tower-shaped magnetic fluid sealing device, which is used to test the sealing performance of the magnetic fluid sealing device. It plays an important role in the later optimization of the pressure resistance of the magnetic fluid sealing structure and has a far-reaching impact on the development of magnetic fluid sealing.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The magnetic fluid sealing device based on the labyrinth tower is sleeved on the outside of the main shaft, including: a housing component and a magnetic fluid sealing component, wherein:

[0008] A housing assembly, comprising a first sealed housing and an end cover, wherein the first sealed housing is sleeved on the outside of the main shaft and is cylindrical as a whole, one end of the first sealed housing is provided with a folded edge portion, and the other end is an opening, the end cover is arranged at the opening of the first sealed housing, and a mounting cavity is formed between the end cover and the folded edge portion, the end cover is connected to the end of the first sealed housing by screws, and in addition, an extension portion is arranged on the circumferential outer wall of the first sealed housing along its radial direction;

[0009] The magnetic fluid sealing assembly is arranged inside the installation cavity and includes:

[0010] A spindle sleeve is fixedly sleeved on the spindle and rotates with the spindle. Two sets of bosses are arranged on the circumferential side wall of the spindle sleeve. Each set of bosses is composed of a number of equally spaced and parallel annular bosses. The height of each annular boss is h, 0.6mm<h<1.4mm, and the width of each annular boss is b, 2.6mm<b<4.4mm.

[0011] A pole shoe assembly, comprising two annular sealing pole shoes of identical structure, the outer circumferential surface of each sealing pole shoe being in contact with the inner circumferential surface of the first sealing housing, a plurality of tower-shaped pole teeth being arranged on the inner circumferential surface of each sealing pole shoe, the tower-shaped pole teeth corresponding to the annular boss one-to-one, and a labyrinth-shaped sealing gap being formed between the tower-shaped pole teeth and the annular boss, a magnetic fluid being arranged in the sealing gap, forming a sealing structure between the main shaft and the sealing pole shoe;

[0012] The sealing gap includes: two symmetrically arranged magnetic fluid channels and a tower top cavity, each of the magnetic fluid channels includes an axial sealing gap and two radial sealing gaps; wherein the gap between the axial pole tooth side wall in the tower-shaped pole tooth and the axial side wall of the annular boss is configured as an axial sealing gap, and the specific gap distance of the axial sealing gap is c2, 0.1mm<c2<1.2mm; the gap between the radial pole tooth side wall in the tower-shaped pole tooth and the circumferential surface of the annular boss, and the gap between the radial pole tooth side wall in the tower-shaped pole tooth and the circumferential surface of the main shaft are both configured as radial sealing gaps, and the specific gap distance of the radial sealing gap is c1, 0.1mm<c1<1.2mm, the two radial sealing gaps are respectively located on both sides of the axial sealing gap, and form a magnetic fluid channel with a stepped structure with the axial sealing gap; the tower top cavity is between the two magnetic fluid channels;

[0013] The magnetic fluid sealing component also includes an annular permanent magnet, which is arranged between the two sealing pole shoes, and the outer circumferential surface of the permanent magnet is also in contact with the inner circumferential surface of the first sealing shell.

[0014] Preferably, in the housing assembly, a clearance hole for the main shaft to pass through is provided in the middle of the end cover, and the end cover is also provided with an annular abutment portion on its side end surface.

[0015] Furthermore, the magnetic fluid sealing assembly also includes:

[0016] The magnetic isolation ring is arranged on one side of the sealed pole shoe, and the magnetic isolation ring, the pole shoe assembly and the permanent magnet are tightly installed in the installation cavity under the abutment of the abutment portion of the end cover;

[0017] The fastening assembly includes a gasket sleeved on the main shaft and located at one side of the main shaft sleeve, and a nut threadedly connected to the end of the main shaft. The gasket is tightened and squeezed by rotating the nut, thereby achieving the fastening installation of the main shaft sleeve.

[0018] Furthermore, in the magnetic fluid sealing assembly, the two sealing pole shoes in the pole shoe group are provided with a first sealing ring at the position where they are in contact with the inner circumferential surface of the first sealing shell; the gasket is provided with a second sealing ring at the position where it is in contact with the end of the main shaft sleeve and a third sealing ring at the position where it is in contact with the circumferential surface of the main shaft.

[0019] Preferably, based on the labyrinth tower-shaped sealing gap in the magnetic fluid sealing assembly, when the width b of the annular boss is constant, the specific gap distance c1 of the radial sealing gap is constant, and the specific gap distance c2 of the axial sealing gap is constant, and the value range of the height h of the annular boss is: 0.6mm<h<1.4mm, the pressure resistance formula y1 of the labyrinth tower-shaped magnetic fluid sealing structure at different heights h of the annular boss is:

[0020] y1=228.38048e -0.449h +48.69637 (0.6<h<1.4)

[0021] In the formula: e is a mathematical transcendental number, e = 2.7182;

[0022] When the height h of the annular boss is constant, the specific gap distance c1 of the radial sealing gap is constant, and the specific gap distance c2 of the axial sealing gap is constant, and the value range of the width b of the annular boss is: 2.6mm<b<4.4mm, the pressure resistance formula y2 of the labyrinth tower-shaped magnetic fluid sealing structure under different widths b of the annular boss is:

[0023] y2=0.00129e 2.11216b |197.11743 (2.6<b<4.4)

[0024] In the formula: e is a mathematical transcendental number, e = 2.7182;

[0025] When the height h of the annular boss is constant, the width b of the annular boss is constant, and the specific gap distance c2 of the axial sealing gap is constant, and the specific gap distance c1 of the radial sealing gap has a value range of: 0.1mm<c1<1.2mm, the pressure resistance formula y3 of the maze tower-shaped magnetic fluid sealing structure under different specific gap distances c1 of the radial sealing gap is:

[0026] y3=418.75-2089.04c1+6346.299c1 2 -8814.048c1 3+5803.038c1 4 -1495058c1 5 (0.1<c1<1.2)

[0027] When the height h of the annular boss is constant, the width b of the annular boss is constant, the specific gap distance c1 of the radial sealing gap is constant, and the specific gap distance c2 of the axial sealing gap has a value range of: 0.1mm<c2<1.2mm, the pressure resistance formula y4 of the maze tower-shaped magnetic fluid sealing structure under different specific gap distances c2 of the axial sealing gap is:

[0028] y4=279.047-1106.14c2+4954.848c2 2 -8649.368c2 3 +6876.179c2 4 -2083.12c2 5 (0.1<c2<1.2).

[0029] In addition, the present invention also provides a sealing performance test bench for a magnetic fluid sealing device based on a maze tower, which is applied to the above-mentioned magnetic fluid sealing device based on a maze tower. The sealing performance test bench includes:

[0030] Test bench;

[0031] The spindle drive assembly includes a variable frequency motor arranged above the test bench through a motor bracket, wherein the output end of the variable frequency motor is connected to one end of the spindle through a coupling;

[0032] A support assembly, comprising a seat bearing installed above the test bench, and the seat bearing is arranged on the main shaft for supporting the main shaft;

[0033] A pressurizing component, comprising a sealing bracket for supporting the magnetic fluid sealing device, and a second sealing shell partially sleeved on the outside of the first sealing shell, wherein a mounting hole is provided in the middle of the sealing bracket for inserting and installing the first sealing shell of the magnetic fluid sealing device, and one side of the sealing bracket abuts against the extension of the first sealing shell; an annular flange is radially provided along the circumferential surface of one end of the second sealing shell, the annular flange is connected to the extension by bolts, and a constant pressure chamber is formed inside the second sealing shell; in addition, the pressurizing component also includes an air pump, which is connected in series with a pressure reducing valve and a throttle valve in sequence through a pipeline, and then connected to the constant pressure chamber through a preset sealing pressurizing hole on the second sealing shell;

[0034] Detection components, including:

[0035] The torque sensor is arranged on the coupling and is used to detect the torque provided by the variable frequency motor to the main shaft;

[0036] A temperature sensor is provided inside the sealing pole shoe through a plurality of first detection holes, and is used to detect the temperature of the magnetic fluid inside the sealing gap when the main shaft rotates;

[0037] The pressure sensor is arranged on the second sealed housing through the second detection hole, and is used for detecting the pressure inside the constant pressure cavity.

[0038] Preferably, the test bench surface includes a supporting plate and a base arranged in a stepped manner from top to bottom, the supporting plate and the base are both made of steel plates, and a plurality of rib plates are provided between the supporting plate and the base. In addition, a plurality of through holes and threaded holes are preset on the supporting plate for accurately positioning and installing the spindle drive assembly, the support assembly, and the pressurizing assembly.

[0039] More preferably, in the support assembly, two bearing seats are provided, and each bearing seat is installed above the bearing plate through a support seat, and on this basis, each bearing seat is interference fit with the main shaft.

[0040] Furthermore, on the basis that the pressurizing assembly and the magnetic fluid sealing device are installed in coordination, a fourth sealing ring is provided at the joint between the extension portion and the annular flange;

[0041] In addition, the pressurizing component also includes a quick connector, which is arranged on the pipeline and is used to cooperate with the sealed pressurizing hole. In addition, the quick connector is a one-way connector that can only allow gas to be input from the air pump into the constant pressure chamber.

[0042] Furthermore, in the detection assembly, the plurality of first detection holes are deep holes and are evenly distributed on the outer wall of the sealing bracket with the center of the main axis as the center of the circle. After the bottoms of the plurality of first detection holes pass through the first sealing shell, they are located inside the sealing pole shoe near the tower-shaped pole teeth. On this basis, a temperature sensor is arranged in each of the first detection holes.

[0043] In addition, the detection component also includes a support platform for supporting the torque sensor, and the support platform is installed on a carrying plate.

[0044] The beneficial effects of the present invention are:

[0045] The present invention sleeves a magnetic fluid sealing component on the outside of a main shaft with a large diameter, sets the pole teeth of each sealing pole shoe into a tower-shaped structure, and utilizes a plurality of annular bosses on the main shaft sleeve to correspond one-to-one with the tower-shaped pole teeth to form a plurality of labyrinth-shaped sealing gaps, and then uses a magnetic fluid set in the sealing gaps to enhance the pressure resistance of the sealing structure, so that the magnetic fluid sealing device based on the labyrinth-shaped tower can still have a good sealing effect under the working conditions of large shaft diameter, high pressure and high speed.

[0046] In addition, the present invention also designs a sealing performance test bench based on the magnetic fluid sealing device. On the basis of using the main shaft drive component to provide the rotation speed and torque for the main shaft and the pressurizing component to provide constant pressure for the sealing part, the detection component is used to adjust different rotation speeds, different pressures and other working conditions to perform real-time testing on the sealing performance of the magnetic fluid sealing device, which has important guiding significance for the design and optimization of the sealing gap structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 It is a schematic diagram of the traditional magnetic fluid sealing structure;

[0049] Figure 2 It is a schematic diagram of the magnetic fluid sealing structure based on the tower-shaped pole teeth;

[0050] Figure 3 This is a schematic cross-sectional structural diagram of a maze-shaped magnetic fluid sealing device provided by the present invention;

[0051] Figure 4 for Figure 3 A schematic diagram of the enlarged structure at A in the middle;

[0052] Figure 5 Likewise Figure 3 A schematic diagram of the enlarged structure at A in the middle;

[0053] Figure 6 It is a schematic diagram of the distribution state of magnetic fluid in the sealing gap under static sealing state;

[0054] Figure 7 It is a schematic diagram of the distribution state of magnetic fluid in the sealing gap under the dynamic sealing state;

[0055] Figure 8 A schematic diagram of the leakage path of the magnetic fluid in this application;

[0056] Fig. 9 A schematic diagram of a two-dimensional plane model established for simulation in this application;

[0057] Fig.10 A schematic diagram of mesh division of the sealing structure;

[0058] Fig.11 is a magnetic field cloud diagram obtained based on the simulation results of the sealing structure;

[0059] Fig.12 is a magnetic force line distribution diagram obtained based on the simulation results of the sealing structure;

[0060] Fig.13 The magnetic flux density curve of the pyramid-shaped pole teeth after selecting a path along the sealing gap in the simulation;

[0061] Fig.14 This is a comparison chart of the pressure resistance of three sealing structures when the height of the annular boss is used as the research variable;

[0062] Fig.15 This is a comparison chart of the pressure resistance of three sealing structures when the width of the annular boss is used as the research variable;

[0063] Fig.16 This is a comparison chart of the pressure resistance of three sealing structures when the radial sealing gap is used as the research variable;

[0064] Fig.17 This is a comparison chart of the pressure resistance of three sealing structures when the axial sealing gap is used as the research variable;

[0065] Fig.18 The figure is a schematic diagram of the specific structure of the sealing performance test bench designed based on the magnetic fluid sealing device of the present invention. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance. In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the concept involved in this application, magnetic fluid sealing means: under the action of an external magnetic field, magnetic fluid is gathered around the pole teeth to form a liquid sealing ring, thereby achieving a sealing effect. Magnetic fluid can adapt well to sealing structures of different shapes and sizes due to its flexibility, and is widely used in mechanical sealing fields such as aerospace, automotive chemicals, and medical and health care due to its good tolerance. However, with the continuous increase in magnetic fluid sealing pressure and spindle speed, the sealing ability of magnetic fluid sealing devices under large shaft diameter, high pressure, and high speed conditions poses a huge challenge.

[0069] The pressure resistance of magnetic fluid seal refers to the ability of the sealing structure containing magnetic fluid to withstand the sealing pressure. Therefore, the pressure resistance of the sealing structure is a direct factor in measuring the sealing effect of the magnetic fluid sealing device. The pressure resistance is reflected in the pressure difference on both sides of the sealing structure. When the main shaft is in a stationary state, the magnetic force exerted by the permanent magnet on the magnetic fluid is sufficient to resist the pressure difference on both sides of the sealing structure, and the sealing structure works normally; when the magnetic force is not enough to resist the pressure difference on both sides of the sealing structure, the sealing structure is destroyed and loses the sealing effect; when the main shaft is in motion, the magnetic force exerted by the permanent magnet on the magnetic fluid and the centrifugal force exerted on the magnetic fluid are used together to resist the pressure difference.

[0070] In a conventional magnetic fluid sealing structure, the pole tooth end on the sealing pole shoe is relatively parallel to the circumferential surface of the main shaft, that is, there is only a uniform radial sealing gap between the pole tooth and the main shaft, and magnetic fluid exists in the radial sealing gap. The specific structure is as follows Figure 1As shown, under the action of the external magnetic field, the magnetic fluid is evenly arranged in the radial sealing gap to form a sealing oil film and play a sealing role. However, the sealing oil film in the sealing structure is easily squeezed to the low-pressure side and ruptured under the action of the pressure difference, causing the seal to be damaged, making the sealing structure ineffective, reflecting the lower sealing stability; in addition, based on the sealing structure, under the working conditions of large shaft diameter, high pressure and high speed, a large centrifugal force will be generated on the magnetic fluid, and the magnetic fluid will be thrown out from the radial sealing gap, thereby weakening the sealing effect, which also reflects the lower sealing stability.

[0071] In order to solve the above problems, the prior art proposes to set a groove at the end of the pole tooth on the sealed pole shoe to form a tower structure, while the main shaft still has a smooth side wall, and there is a sealed gap between the tower-shaped pole tooth and the smooth side wall of the main shaft. There is a magnetic fluid in the sealed gap. The specific structure is as follows Figure 2 As shown, when the sealing oil film in the sealing structure moves toward the low-pressure side under the action of a large pressure difference, the magnetic fluid will be surrounded by the side walls of the tower-shaped structure, making it difficult for the magnetic fluid to squeeze out of the tower-shaped pole teeth, thereby improving the sealing stability; in addition, when the magnetic fluid under this sealing structure is subjected to the action of centrifugal force, although the interior of the tower-shaped pole teeth will contain the magnetic fluid to prevent the magnetic fluid from being thrown out of the sealing gap, the overall pressure resistance of the sealing structure is still lacking, and it is difficult to meet the requirements under higher pressure and higher speed conditions.

[0072] Therefore, how to obtain a magnetic fluid sealing device with stronger adaptability by performing low-cost and small-scale technical improvements is an urgent problem to be solved by those skilled in the art.

[0073] Therefore, based on the innovation of the sealing structure and based on the determination and comparison of the pressure resistance of the sealing structure, this application proposes a magnetic fluid sealing device based on a labyrinth tower to achieve reliable sealing of gaseous media under high pressure and high speed conditions for a large diameter main shaft.

[0074] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0075] In this technical solution, a maze-shaped magnetic fluid sealing device is sleeved on the outside of the main shaft 1 with a large diameter, such as Figure 3 As shown, the magnetic fluid sealing device comprises: a housing component 2, a magnetic fluid sealing component 3, wherein:

[0076] like Figure 3As shown, the housing assembly 2 includes a first sealed housing 201 and an end cover 202, wherein the first sealed housing 201 is sleeved on the outside of the main shaft 1 and is cylindrical as a whole, one end of the first sealed housing 201 is provided with a folded edge portion 203, and the other end is an opening, the end cover 202 is arranged at the opening of the first sealed housing 201, and a mounting cavity is formed between the end cover 202 and the folded edge portion 203, and the end cover 202 is connected to the end of the first sealed housing 201 by screws; in addition, an extension portion 204 is provided on the circumferential outer wall of the first sealed housing 201 along its radial direction, a clearance hole for the main shaft 1 to pass through is provided in the middle of the end cover 202, and the end cover 202 is also provided with an annular abutment portion 205 on its side end surface.

[0077] The magnetic fluid sealing assembly 3 is arranged inside the installation cavity, such as Figure 3-4 As shown, including:

[0078] The spindle sleeve 301 is fixedly sleeved on the spindle 1 and rotates with the spindle 1. Two groups of bosses are arranged on the circumferential side wall of the spindle sleeve 301. Each group of bosses is composed of a plurality of annular bosses 4 which are equally spaced and arranged in parallel.

[0079] The pole shoe group includes two annular sealed pole shoes 302 with completely identical structures. The outer circumference of each sealed pole shoe 302 is in contact with the inner circumference of the first sealed shell 201. A plurality of tower-shaped pole teeth 303 are arranged on the inner circumference of each sealed pole shoe 302. In this embodiment, three tower-shaped pole teeth 303 are arranged on each sealed pole shoe 302 as an example for explanation.

[0080] The magnetic fluid sealing assembly 3 further includes an annular permanent magnet 7 , which is disposed between the two sealing pole shoes 302 , and the outer circumferential surface of the permanent magnet 7 is also in contact with the inner circumferential surface of the first sealing housing 201 .

[0081] As the core of the present invention, Figure 3-4 As shown, the tower-shaped pole teeth 303 correspond to the annular bosses 4 one by one, and a labyrinth-shaped sealing gap 6 is formed between the tower-shaped pole teeth 303 and the annular bosses 4. A magnetic fluid 5 is arranged in the sealing gap 6 to form a sealing structure between the main shaft 1 and the sealing pole shoe 302. For the sake of clarity, the magnetic fluid 5 is arranged in the sealing gap 6. Figure 3-4 Not shown, see Figure 6-7 shown.

[0082] Specifically, Figure 5 As shown, the sealing gap 6 includes: two symmetrically arranged magnetic fluid channels and a tower top cavity 601 , and each magnetic fluid channel includes an axial sealing gap 602 and two radial sealing gaps 603 .

[0083] The gap between the axial pole tooth side wall 304 in the tower-shaped pole tooth 303 and the axial side wall of the annular boss 4 is configured as an axial sealing gap 602. Figure 4-5 As shown, c2 represents the specific gap distance of the axial sealing gap 602 .

[0084] The gap between the radial pole tooth side wall 305 in the tower-shaped pole tooth 303 and the circumferential surface of the annular boss 4, and the gap between the radial pole tooth side wall 305 in the tower-shaped pole tooth 303 and the circumferential surface of the main shaft 1 are both configured as radial sealing gaps 603. The two radial sealing gaps 603 are respectively located on both sides of the axial sealing gap 602, and form a stepped magnetic fluid channel with the axial sealing gap 602, such as Figure 4-5 As shown, c1 represents the specific gap distance of the radial sealing gap 603; the tower top cavity 601 is between the two magnetic fluid channels.

[0085] Based on the above structure, when the main shaft 1 is stationary, under the action of the permanent magnet 7, the state of the magnetic fluid 5 in the sealing gap 6 is as follows: Figure 6 As shown, the cooperation between the magnetic fluid 5 and the sealing gap makes the movement of the magnetic fluid 5 toward the low-pressure side slow down or even stop due to the tortuous magnetic fluid channel when the magnetic fluid 5 is subjected to a pressure difference, thereby reflecting that the pressure resistance of the sealing structure is stronger than that of the original sealing structure in the prior art.

[0086] When the main shaft 1 rotates, centrifugal force is generated on the magnetic fluid 5. The magnetic force of the permanent magnet 7 and the centrifugal force will also cause the magnetic fluid 5 in the sealing gap 6 to move, and the tortuous magnetic fluid channel will slow down the movement of the magnetic fluid 5. In this case, the tower top cavity 601 in the tower-shaped pole tooth 303 accommodates the moving magnetic fluid 5. The specific state is as follows: Figure 7 As shown, compared with the original sealing structure in the prior art, the same content of magnetic fluid 5 fills the labyrinth tower-shaped sealing gap more fully, so that under the cooperation of the magnetic fluid 5 and the tortuous magnetic fluid channel, the dual effects of centrifugal force and magnetic force further provide an effective improvement in the pressure resistance of the sealing structure provided by the present application.

[0087] In addition, the premise of ensuring the pressure resistance of the sealing structure of the present application is the limited installation of the main shaft sleeve 301, the pole shoe assembly, and the permanent magnet 7. Specifically, Figure 3As shown, the magnetic fluid sealing component 3 also includes: a magnetic isolation ring 306 and a fastening component 307; wherein, the magnetic isolation ring 306 is arranged on one side of the sealing pole shoe 302, and the magnetic isolation ring 306, the pole shoe group and the permanent magnet 7 are tightly installed in the installation cavity under the abutment action of the abutment portion 205 of the end cover 202; the fastening component 307 includes a gasket 308 which is sleeved on the main shaft 1 and is also located on one side of the main shaft sleeve 301, and a nut 309 which is threadedly connected to the end of the main shaft 1. The gasket 308 is tightened and squeezed by rotating the nut 309, thereby realizing the fastening installation of the main shaft sleeve 301. At this time, the matching installation of the magnetic fluid sealing component 3 is achieved, that is, the clearance between the tower-shaped pole teeth 303 in the sealing pole shoe 302 and the annular boss 4 is matched.

[0088] Furthermore, if Figure 3 As shown, in the magnetic fluid sealing assembly 3, the two sealing pole shoes 302 in the pole shoe group are provided with a first sealing ring 310 at the position where they fit with the inner circumferential surface of the first sealing shell 201; the gasket 308 is provided with a second sealing ring 311 at the position where it fits with the end of the main shaft sleeve 301, and is provided with a third sealing ring 312 at the position where it fits with the circumferential surface of the main shaft 1. The arrangement of the above three sealing rings enables the magnetic fluid sealing device to prevent medium leakage when in use.

[0089] Next, the present application will use the simulation demonstration method to specifically demonstrate the influence of each sealing gap in the above-mentioned sealing structure on the pressure resistance of the sealing structure. Among them, since the sealing structure provided by the present application is more complex than the traditional sealing structure, the pressure resistance of the main shaft 1 under the rotating condition needs to consider more factors. Therefore, after it has been determined that the pressure resistance of the sealing structure can be effectively improved when the main shaft 1 is rotating, the present application does not consider the main shaft 1 in the rotating condition, that is, does not consider the dynamic pressure resistance, on the premise of demonstrating that the main shaft 1 has produced better pressure resistance effect than the traditional sealing structure when it is stationary.

[0090] Using the Bernoulli basic equation in magnetic fluid proposed by Rosensweig:

[0091]

[0092] Where: f —density of magnetic fluid; V—flow velocity of magnetic fluid when it is subjected to sealing pressure; P—sealing pressure to which magnetic fluid is subjected; g—gravitational acceleration of magnetic fluid; h—height of magnetic fluid relative to the reference point of gravity level; H—magnetic field strength at the sealing gap; M S —saturation magnetization of magnetic fluid; C—constant; μ0—vacuum magnetic permeability (4π×10 -7 H / m).

[0093] Under the premise of formula (1), according to the document "Journal of Magnetism and Magnetic Materials 582 (2023) 170978" in the prior art, under the premise that the sealing structure is a multi-stage seal, when the sealing structure is in a static sealing state, the pressure resistance of the sealing structure can be simplified as:

[0094]

[0095] Where: M S —saturation magnetization of magnetic fluid; N—number of pole teeth; B i max —The maximum magnetic flux density of the i-th pyramid pole tooth; B i min —Minimum magnetic flux density of the ith pyramid pole tooth; H i max —The maximum magnetic field intensity of the ith pyramid pole tooth; H i min —The minimum magnetic field intensity of the ith pyramid pole tooth; μ0—vacuum magnetic permeability (4π×10 -7 H / m).

[0096] Among them, multi-stage sealing means that multiple pole teeth work together; static sealing means that the main shaft 1 is in a stationary state.

[0097] Due to the pressure difference on both sides of the sealing structure, the magnetic fluid 5 will move to the low-pressure side under the action of the pressure difference until the pressure difference and the magnetic force are balanced. At this time, the path through which the magnetic fluid 5 moves in the sealing gap is defined as the leakage path. In any one of the tower-shaped pole teeth 303, due to the presence of the annular boss 4, the two symmetrical magnetic fluid channels formed are the leakage paths of the magnetic fluid 5.

[0098] In the specific tower structure sealing gap, such as Figure 8 As shown in the middle orientation, when the high pressure that generates the pressure difference is on the left side of the tower-shaped pole tooth 303, the leakage path of the magnetic fluid 5 is to the right. Since the stepped magnetic fluid channel produces different main shaft 1 diameters in the sealing gap, the leakage path from the left side of the annular boss 4 to the tower top cavity 601 is defined as a divergent leakage path; the leakage path from the tower top cavity 601 to the right side of the annular boss 4 is defined as a convergent leakage path; that is: in any tower-shaped pole tooth 303 of the present application, the two stepped magnetic fluid channels from left to right are respectively a divergent leakage path and a convergent leakage path.

[0099] Under each divergent leakage path in the several tower-shaped pole teeth 303 of the present application, the pressure resistance formula of the sealing structure is:

[0100]

[0101] Where: P r —The sum of the pressure resistance of the radial sealing gap in the current pyramid-shaped pole teeth; P a —The sum of the pressure resistance of the axial sealing gap in the current pyramid-shaped pole teeth; N—the number of pole teeth; λ is the coefficient.

[0102] At the same time, under each convergent leakage path in the several tower-shaped pole teeth 303 of the present application, the pressure resistance formula of the sealing structure is:

[0103]

[0104] Where: P r —The sum of the pressure resistance of the radial sealing gap in the current pyramid-shaped pole teeth; P a —The sum of the pressure resistance of the axial sealing gap in the current pyramid-shaped pole teeth; N—the number of pole teeth; λ is the coefficient.

[0105] By combining formula (2), formula (3), and formula (4), we can obtain the total pressure resistance formula of the sealing structure composed of a plurality of tower-shaped pole teeth 303 and the magnetic fluid 5:

[0106] ΔP=ΔP1+ΔP2 Formula (5)

[0107] More specifically, under the conditions of the magnetic fluid 5 and the permanent magnet 7 used in the present application, the factors affecting the sealing gap of the labyrinth tower structure are: the height h of the annular boss 4, the width b of the annular boss 4, the specific gap distance c1 of the radial sealing gap 603, and the specific gap distance c2 of the axial sealing gap 602; the present application will use the above-mentioned influencing factors to construct a finite element simulation model, and derive the relationship between the above-mentioned factors and the magnetic flux density of the labyrinth tower sealing structure, and then obtain the relationship with the total withstand pressure.

[0108] S1. Model building

[0109] Since the magnetic fluid sealing structure provided in the present application is axially symmetrical, the same radial cross section produces the same result in the magnetic field simulation analysis. Therefore, in order to simplify the calculation, the magnetic fluid sealing structure adopts a two-dimensional model for numerical simulation, and a two-dimensional plane model is established as follows: Fig. 9 As shown, the design parameters in the model are as follows:

[0110]

[0111] S2. Grid division

[0112] The grid shape is a quadrilateral. In order to accurately study the dramatic change of the magnetic flux density in the sealing gap 6 near the sealing pole shoe 302, the grid at the sealing gap 6 is locally encrypted, such as Fig.10 shown.

[0113] S3. Conduct finite element simulation of magnetic field

[0114] The finite element software ANSYS APDL is used to carry out numerical simulation of the magnetic field distribution of the labyrinth tower seal structure. The Magnetic-Nodal module is selected to simulate the magnetic field environment. The two-dimensional mesh model is imported, and the PLANE13 unit and Axisymmetric axisymmetric option are selected.

[0115] S31, define the material properties of permanent magnet 7, sealed pole shoe 302, main shaft 1 and air: the magnetic permeability of air is 1; the material of permanent magnet 7 is Nd-Fe-B, its relative magnetic permeability is 1.05, and the coercive force is 8.9105A / m; the magnetization direction of permanent magnet 7 is along the axial direction; the material of sealed pole shoe 302 and main shaft 1 is 2Cr13 with good magnetic conductivity; because the relative magnetic permeability of magnetic fluid 5 is similar to that of air, the relative magnetic permeability of magnetic fluid 5 is set to 1. Apply the parallel boundary condition of magnetic lines of force to perform simulation calculation, and get the following Fig.11 The magnetic field cloud diagram shown, and Fig.12 The magnetic field line distribution diagram shown reflects the magnetic field distribution of each part under the sealing structure and the rationality of the magnetic circuit.

[0116] S32, select a path along the sealing gap 6, and the total length of the path is L. Take the case where the height h of the annular boss 4 is 4 mm, the width b of the annular boss 4 is 3.4 mm, c1 is 0.2 mm, and c2 is 0.2 mm as an example, extract the simulation result data in the path to obtain the following Fig.13 The magnetic flux density curve and data of the tower-shaped pole teeth 303 are shown. After substituting the data into formula (5), the total withstand voltage value of the sealing structure under the above conditions can be obtained.

[0117] ① Based on the above simulation process, when the width b of the annular boss 4 is constant, the specific gap distance c1 of the radial sealing gap 603 is constant, and the specific gap distance c2 of the axial sealing gap 602 is constant, the selection of different heights h of the annular boss 4 can obtain different groups of magnetic flux density data of each tower-shaped pole tooth 303, and then the different total withstand voltage values ​​of the sealing structure under the above conditions can be obtained. After fitting, the withstand voltage formula of the labyrinth tower-shaped magnetic fluid sealing structure under different heights h of the annular boss 4 is obtained:

[0118] y1=228.38048e -0.449h +48.69637 (0.6<h<1.4) Formula (6)

[0119] In the formula: e—is a mathematical transcendental number, e=2.7182.

[0120] ② Based on the above simulation process, when the height h of the annular boss 4 is constant, the specific gap distance c1 of the radial sealing gap 603 is constant, and the specific gap distance c2 of the axial sealing gap 602 is constant, the selection of different widths b of the annular boss 4 can also obtain different groups of magnetic flux density data of each tower-shaped pole tooth 303, and then obtain different total withstand voltage values ​​of the sealing structure under the above conditions. After fitting, the withstand voltage formula of the labyrinth tower-shaped magnetic fluid sealing structure under different widths b of the annular boss 4 is obtained:

[0121] y2=-0.00129e 2.11216b +197.11743 (2.6<b<4.4) Formula (7)

[0122] In the formula: e—is a mathematical transcendental number, e=2.7182.

[0123] ③ Based on the above simulation process, when the height h of the annular boss 4 is constant, the width b of the annular boss 4 is constant, and the specific gap distance c2 of the axial sealing gap 602 is constant, the selection of different specific gap distances c1 of the radial sealing gap 603 can also obtain different groups of magnetic flux density data of each tower-shaped pole tooth 303, and then obtain different total withstand voltage values ​​of the sealing structure under the above conditions. After fitting, the withstand voltage formula of the labyrinth tower-shaped magnetic fluid sealing structure under different specific gap distances c1 of the radial sealing gap 603 is obtained:

[0124]

[0125] ④ Based on the above simulation process, when the height h of the annular boss 4 is constant, the width b of the annular boss 4 is constant, and the specific gap distance c1 of the radial sealing gap 603 is constant, the selection of different specific gap distances c2 of the axial sealing gap 602 can also obtain different groups of magnetic flux density data of each tower-shaped pole tooth 303, and then obtain different total withstand voltage values ​​of the sealing structure under the above conditions. After fitting, the withstand voltage formula of the labyrinth tower-shaped magnetic fluid sealing structure under different specific gap distances c2 of the axial sealing gap 602 is obtained:

[0126]

[0127] It should be noted that this application will use the formula obtained from the above-mentioned influencing factors to successively compare the total pressure resistance of the sealing structure in the following three structural conditions:

[0128] Traditional structure: There is only a uniform radial sealing gap between the pole teeth and the main shaft. The specific structure is as follows Figure 1 As shown;

[0129] Tower structure: There is a sealed gap between the tower-shaped pole teeth and the smooth side wall of the main shaft. The specific structure is as follows Figure 2 As shown;

[0130] Labyrinth tower structure: The tower-shaped pole teeth and the annular boss cooperate to form a sealing gap. The specific structure is as follows: Figure 4 Shown

[0131] ① When the height h of the annular boss 4 is used as the research variable, it should be noted that: since the tower structure and the traditional structure do not have an annular boss, in the tower structure, the height h of the annular boss is as follows: Figure 2 As shown in h1; this variable control is not considered in the traditional structure, so the withstand voltage remains unchanged.

[0132] Substitute the maximum and minimum values ​​of the magnetic flux density at the pole teeth corresponding to the magnetic flux density curve extracted at the sealing gap 6 into formulas (2)-(5) to obtain the withstand voltage value, and then obtain the following: Fig.14 The linear comparison diagram is shown in the figure. As shown in the figure: with the increase of h and h1, the pressure resistance of the tower structure and the labyrinth tower structure shows a downward trend as a whole, but is much greater than the pressure resistance of the traditional structure. Among them, the downward trend of the pressure resistance of the labyrinth tower structure is greater than that of the tower structure. This is because as the height h of the annular boss 4 of the labyrinth tower structure increases, the width of the end small tooth of the tower pole tooth increases in the axial direction, and more magnetic flux lines pass through the axial end face of the small tooth, resulting in a greater decrease in the magnetic flux density of the radial end face of the small tooth. However, at this time, the sum of the pressure resistance of the radial sealing gap is still greater than the sum of the pressure resistance of the axial sealing gap. According to formula (3), at this time, the total pressure resistance of the divergent leakage path only calculates the pressure resistance of the radial sealing gap. Therefore, the downward trend of the overall pressure resistance of the labyrinth tower structure is greater than that of the tower structure.

[0133] ② When the width b of the annular boss 4 is used as the research variable, it should be noted that: since the tower structure and the traditional structure do not have an annular boss, in the tower structure, the width b of the annular boss is as follows: Figure 2 In the conventional structure, the width b of the annular boss is the width b2 of the pole tooth body, as shown in FIG. Figure 1 shown.

[0134] Substitute the maximum and minimum values ​​of the magnetic flux density at the pole teeth corresponding to the magnetic flux density curve extracted at the sealing gap 6 into formulas (2)-(5) to obtain the withstand voltage value, and then obtain the following: Fig.15As shown in the linear comparison diagram, as shown in the figure: the pressure resistance of the labyrinth tower structure is greater than that of the tower structure, and is much greater than that of the traditional structure; in terms of trend, the pressure resistance of the labyrinth tower structure is on a downward trend. This is because as the width b of the annular boss 4 increases, the radial width of the small teeth at the end of the tower pole teeth becomes smaller, the amount of magnetic flux lines passing through becomes smaller, the magnetic flux density becomes smaller, and the pressure resistance decreases; the pressure resistance of the tower structure first increases and then decreases. This is because as the radial width of the small teeth at the end of the tower pole teeth becomes smaller, the tip magnetic field effect is also increased to a certain extent. However, as the radial width of the small teeth further decreases, the influence of the magnetic field effect on the tower sealing structure is less than the influence of the reduction of magnetic flux lines. Therefore, the pressure resistance of the tower structure first increases and then begins to decrease.

[0135] ③ When the specific gap distance c1 of the radial sealing gap 603 is used as the research variable, it should also be noted that: in the tower structure, the specific gap distance of the radial sealing gap is as follows: Figure 2 As shown in c3; in the conventional structure, the specific gap distance of the radial sealing gap is as follows Figure 1 Shown as c4.

[0136] Substitute the maximum and minimum values ​​of the magnetic flux density at the pole teeth corresponding to the magnetic flux density curve extracted at the sealing gap 6 into formulas (2)-(5) to obtain the withstand voltage value, and then obtain the following: Fig.16 As shown in the linear comparison diagram, as shown in the figure: the pressure resistance of the labyrinth tower structure is always greater than the pressure resistance of the tower structure and the traditional structure; in terms of trend, the pressure resistance of the labyrinth tower structure first decreases, then increases, and then decreases with the increase of the radial sealing gap c1. When the radial sealing gap begins to increase, the magnetic resistance at the radial sealing gap becomes larger, the magnetic flux density decreases, and the pressure resistance decreases; as the radial sealing gap further increases, since the axial sealing gap c2 remains unchanged, most of the magnetic flux lines are affected by the increase in the magnetic resistance of the radial sealing gap and gather toward the axial sealing gap, which increases the pressure resistance of the axial sealing gap of the small teeth at the end of the tower-shaped pole teeth, thereby increasing the pressure resistance of the overall structure; and as the radial sealing gap continues to increase, the small teeth at the end of the tower-shaped pole teeth are staggered with the annular boss, and the axial sealing gap cannot be formed, and the pressure resistance of the axial sealing gap cannot be formed, resulting in a downward trend in the pressure resistance of the overall structure.

[0137] ④ When the specific gap distance c2 of the axial sealing gap 602 is taken as the research variable, it should also be noted that: since there is no axial sealing gap in the tower structure and the traditional structure, the pressure resistance remains unchanged.

[0138] Substitute the maximum and minimum values ​​of the magnetic flux density at the pole teeth corresponding to the magnetic flux density curve extracted at the sealing gap 6 into formulas (2)-(5) to obtain the withstand voltage value, and then obtain the following: Fig.17As shown in the linear comparison diagram, as shown in the figure: the pressure resistance of the labyrinth tower structure is always greater than the pressure resistance of the tower structure and the traditional structure; in terms of trend, the pressure resistance of the labyrinth tower structure first decreases, then increases, and then decreases with the increase of the axial sealing gap c2. When the axial sealing gap begins to increase, the magnetic resistance at the axial sealing gap becomes larger, the magnetic flux density decreases, and the pressure resistance decreases; as the axial sealing gap further increases, since the radial sealing gap c1 remains unchanged, most of the magnetic flux lines are affected by the increase in the magnetic resistance of the axial sealing gap and gather toward the radial sealing gap, so that the radial sealing gap pressure resistance of the small teeth at the end of the tower-shaped pole teeth increases, thereby increasing the pressure resistance of the overall structure; and as the axial sealing gap continues to increase, the small teeth at the end of some tower-shaped pole teeth are staggered with the annular boss, and this part of the radial sealing gap cannot be formed, and thus the pressure resistance of the radial sealing gap cannot be formed, resulting in a downward trend in the pressure resistance of the overall structure.

[0139] To sum up, the pressure resistance of the labyrinth tower sealing structure is greater than that of the tower structure without annular boss and much greater than that of the traditional structure. Therefore, the present invention realizes magnetic fluid sealing under higher pressure environment, and solves the problem that the traditional magnetic fluid sealing structure cannot meet the sealing requirements under large shaft diameter, high pressure and high speed conditions.

[0140] In addition, the present invention also provides a sealing performance test bench used for the above-mentioned magnetic fluid sealing device, which is used to test the sealing performance of the magnetic fluid sealing device. It plays an important role in the later optimization of the pressure resistance of the magnetic fluid sealing device and has a far-reaching impact on the development of magnetic fluid sealing.

[0141] Specifically, in this technical solution, if Fig.18 As shown, the sealing performance test bench includes: a test bench surface 8, a spindle drive assembly 9, a support assembly 10, a pressurizing assembly 11, and a detection assembly 12.

[0142] The test table 8 includes a load plate 801 and a base 802 arranged in a stepped manner from top to bottom. Both the load plate 801 and the base 802 are made of steel plates, and a plurality of rib plates 803 are provided between the load plate 801 and the base 802. In addition, a plurality of through holes and threaded holes are preset on the load plate 801 for accurately positioning and installing the spindle drive assembly 9, the support assembly 10, and the pressurizing assembly 11.

[0143] Based on the above embodiments, the sealing performance test bench provided in the present application has a test bench surface 8 that firmly supports the entire device. The load-bearing plate 801 and the base 802 are both made of welded steel plates, which meet the strength and rigidity requirements and provide a structural basis for stable experiments on the test bench.

[0144] In this technical solution, if Fig.18As shown, the spindle drive assembly 9 includes a variable frequency motor 902 disposed above the test bench 8 via a motor bracket 901. The output end of the variable frequency motor 902 is connected to one end of the spindle 1 via a coupling 903. Through the cooperation between the coupling 903 and the variable frequency motor 902, the spindle 1 obtains rotational power and torque.

[0145] The support assembly 10 includes two bearing seats 1002 mounted on the carrier plate 801 through support seats 1001 , and each bearing seat 1002 is disposed on the main shaft 1 and has an interference fit with the main shaft 1 for supporting the main shaft 1 .

[0146] It should be noted here that, since the magnetic fluid sealing device provided by the above technical solution mainly illustrates the core technical features of the labyrinth tower-shaped sealing gap 6, the housing assembly 2 in the present application can be adaptively adjusted and set according to actual conditions on the basis of ensuring that the spindle sleeve 301, the pole shoe assembly, and the permanent magnet 7 are limitedly installed to finally form the labyrinth tower-shaped sealing gap 6. Therefore, as another core of the present invention, the present application proposes a sealing performance test bench based on the core features of the magnetic fluid sealing device, and uses a pressurizing assembly 11 to cooperate with the magnetic fluid sealing device for installation to simulate the use conditions of the magnetic fluid sealing structure.

[0147] Specifically, Figure 3 , Fig.18 As shown, the pressurizing assembly 11 includes a sealing bracket 1101 for supporting the magnetic fluid sealing device, and a second sealing shell 1102 partially sleeved outside the first sealing shell 201 .

[0148] Among them, a mounting hole is provided in the middle of the sealing bracket 1101 for inserting and installing the first sealing shell 201 of the magnetic fluid sealing device, and one side of the sealing bracket 1101 is abutted against the extension part 204 of the first sealing shell 201; one end of the second sealing shell 1102 is radially provided with an annular flange 1104 along its circumferential surface, and the annular flange 1104 is connected to the extension part 204 by bolts, and a constant pressure chamber 1106 is formed inside the second sealing shell 1102.

[0149] In addition, the pressurizing component 11 also includes an air pump 1107. The air pump 1107 is connected in series with a pressure reducing valve 1108 and a throttle valve 1109 through pipelines, and then connected to the constant pressure chamber 1106 through a sealed pressurizing hole 1110 preset on the second sealed shell 1102. Specifically, a quick connector 1111 is provided at the end of the pipeline for connecting with the sealed pressurizing hole 1110, and the quick connector 1111 is a one-way connector that can only supply gas from the air pump 1107 to the constant pressure chamber 1106.

[0150] Based on the above embodiment, the air pump 1107 in the pressurizing component 11 is used in conjunction with the pressure reducing valve 1108, the throttle valve 1109, and the quick connector 1111 to provide constant pressure for the constant pressure chamber 1106, and then the constant pressure chamber 1106 is used to simulate the specific operating conditions of the magnetic fluid sealing device to provide a pressure environment for it. Among them, the air pump 1107, the pressure reducing valve 1108, the throttle valve 1109, and the quick connector 1111 are commonly used equipment for providing constant pressure in the mechanical field, and their usage is also well known to those skilled in the art, so the process of providing constant pressure is not elaborated in detail here; and in order to ensure the accuracy of the experimental results, in this technical solution, on the basis of the pressurizing component 11 and the magnetic fluid sealing device being installed in conjunction, the extension portion 204 is provided with a fourth sealing ring 206 at the fitting position with the annular flange 1104 to prevent constant pressure leakage.

[0151] Therefore, the test bench provided in the present application can simulate high-pressure and high-speed working conditions for the main shaft 1 and the magnetic fluid sealing device based on the above-mentioned structure. As for the sealing effect of the magnetic fluid sealing device, such as the maximum sealing pressure that the sealing device can withstand, the maximum speed of the main shaft 1 and other parameters, the detection component 12 is required to carry out the detection.

[0152] In this technical solution, the detection component 12 includes: a torque sensor 1201 , a temperature sensor 1202 , and a pressure sensor 1203 .

[0153] like Fig.18 As shown, the torque sensor 1201 is mounted on the supporting plate 801 via a supporting platform 1204 .

[0154] like Figure 3 As shown, there are several temperature sensors 1202, and they are arranged inside the sealing pole shoe 302 through several first detection holes 1205, wherein the several first detection holes 1205 are all deep holes, and are evenly distributed on the outer wall of the sealing bracket 1101 with the center of the main shaft 1 as the center of the circle, and the bottoms of the several first detection holes 1205 pass through the first sealing shell 201 and are located inside the sealing pole shoe 302 near the tower-shaped pole teeth 303; on this basis, a temperature sensor 1202 is arranged in each first detection hole 1205.

[0155] Based on the above embodiment, each first detection hole 1205 extends to a position inside the sealing pole shoe 302 close to the tower-shaped pole tooth 303. By detecting the temperature of the tower-shaped pole tooth 303, the temperature of the magnetic fluid 5 inside the sealing gap 6 when the magnetic fluid sealing structure is working can be approximately considered.

[0156] like Figure 3 As shown, the pressure sensor 1203 is disposed on the second sealed housing 1102 through the second detection hole 1206 to detect the pressure inside the constant pressure chamber 1106 .

[0157] At this point, the above test bench can carry out specific testing on the sealing effect of the magnetic fluid sealing device.

[0158] Specifically, when the sealing performance of the magnetic fluid sealing device is tested using the above test bench:

[0159] First, the spindle drive assembly 9, the support assembly 10, the magnetic fluid sealing device and the pressurizing assembly 11 are arranged in sequence on the test bench 8, wherein the installation of the magnetic fluid sealing device is the core, and the spindle drive assembly 9, the support assembly 10 and the pressurizing assembly 11 are all arranged in conjunction with the magnetic fluid sealing device.

[0160] Then the detection component 12 needs to be integrated into the spindle drive component 9, the magnetic fluid sealing device and the pressurizing component 11, and each sensor is installed to the corresponding installation test point for the final device calibration.

[0161] Static pressure test: Open the air pump 1107 to start supplying air, then open the pressure reducing valve 1108 to set the air pressure reference, and then open the throttle valve 1109 to allow gas to fill into the constant pressure chamber 1106 to provide a constant pressure environment for the magnetic fluid sealing device; then gradually increase the pressure to start testing the sealing performance of the magnetic fluid sealing device.

[0162] Dynamic pressure test: Based on the static pressure test, the constant pressure chamber 1106 provides constant pressure, and then the variable frequency motor 202 is started to make the main shaft 1 test the sealing performance of the magnetic fluid sealing device in the test sequence of low speed, medium speed and high speed.

[0163] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetic fluid sealing device based on a labyrinth tower is sleeved on the outside of a main shaft with a large diameter, characterized in that: It includes: a shell assembly and a magnetic fluid sealing assembly, wherein: A housing assembly, comprising a first sealed housing and an end cover, wherein the first sealed housing is sleeved on the outside of the main shaft and is cylindrical as a whole, one end of the first sealed housing is provided with a folded edge portion, and the other end is an opening, the end cover is arranged at the opening of the first sealed housing, and a mounting cavity is formed between the end cover and the folded edge portion, the end cover is connected to the end of the first sealed housing by screws, and in addition, an extension portion is arranged on the circumferential outer wall of the first sealed housing along its radial direction; The magnetic fluid sealing assembly is arranged inside the installation cavity and includes: A spindle sleeve is fixedly sleeved on the spindle and rotates with the spindle. Two sets of bosses are arranged on the circumferential side wall of the spindle sleeve. Each set of bosses is composed of a number of equally spaced and parallel annular bosses. The height of each annular boss is h, 0.6mm<h<1.4mm, and the width of each annular boss is b, 2.6mm<b<4.4mm. A pole shoe assembly, comprising two annular sealing pole shoes of identical structure, the outer circumferential surface of each sealing pole shoe being in contact with the inner circumferential surface of the first sealing housing, a plurality of tower-shaped pole teeth being arranged on the inner circumferential surface of each sealing pole shoe, the tower-shaped pole teeth corresponding to the annular boss one-to-one, and a labyrinth-shaped sealing gap being formed between the tower-shaped pole teeth and the annular boss, a magnetic fluid being arranged in the sealing gap, forming a sealing structure between the main shaft and the sealing pole shoe; The sealing gap includes: two symmetrically arranged magnetic fluid channels and a tower top cavity, each of the magnetic fluid channels includes an axial sealing gap and two radial sealing gaps; wherein the gap between the axial pole tooth side wall in the tower-shaped pole tooth and the axial side wall of the annular boss is configured as an axial sealing gap, and the specific gap distance of the axial sealing gap is c2, 0.1mm<c2<1.2mm; the gap between the radial pole tooth side wall in the tower-shaped pole tooth and the circumferential surface of the annular boss, and the gap between the radial pole tooth side wall in the tower-shaped pole tooth and the circumferential surface of the main shaft are both configured as radial sealing gaps, and the specific gap distance of the radial sealing gap is c1, 0.1mm<c1<1.2mm, the two radial sealing gaps are respectively located on both sides of the axial sealing gap, and form a magnetic fluid channel with a stepped structure with the axial sealing gap; the tower top cavity is between the two magnetic fluid channels; The magnetic fluid sealing component also includes an annular permanent magnet, which is arranged between the two sealing pole shoes, and the outer circumferential surface of the permanent magnet is also in contact with the inner circumferential surface of the first sealing shell.

2. The magnetic fluid sealing device based on the labyrinth tower according to claim 1 is characterized in that: In the housing assembly, a clearance hole for the main shaft to pass through is provided in the middle of the end cover, and an annular abutment portion is provided on the side end surface of the end cover.

3. The magnetic fluid sealing device based on the labyrinth tower according to claim 2 is characterized in that: The magnetic fluid sealing assembly also includes: The magnetic isolation ring is arranged on one side of the sealed pole shoe, and the magnetic isolation ring, the pole shoe assembly and the permanent magnet are tightly installed in the installation cavity under the abutment of the abutment portion of the end cover; The fastening assembly includes a gasket sleeved on the main shaft and located at one side of the main shaft sleeve, and a nut threadedly connected to the end of the main shaft. The gasket is tightened and squeezed by rotating the nut, thereby achieving the fastening installation of the main shaft sleeve.

4. The magnetic fluid sealing device based on the labyrinth tower according to claim 3 is characterized in that: In the magnetic fluid sealing assembly, the two sealing pole shoes in the pole shoe group are provided with a first sealing ring at the position where they fit with the inner circumferential surface of the first sealing shell; the gasket is provided with a second sealing ring at the position where it fits with the end of the main shaft sleeve and a third sealing ring at the position where it fits with the circumferential surface of the main shaft.

5. The magnetic fluid sealing device based on the labyrinth tower according to claim 4 is characterized in that: Based on the labyrinth tower-shaped sealing gap in the magnetic fluid sealing assembly, when the width b of the annular boss is constant, the specific gap distance c1 of the radial sealing gap is constant, and the specific gap distance c2 of the axial sealing gap is constant, and the value range of the height h of the annular boss is: 0.6mm<h<1.4mm, the pressure resistance formula y1 of the labyrinth tower-shaped magnetic fluid sealing structure at different heights h of the annular boss is: y1=228.38048e -0.449h +48.69637 (0.6<h<1.4) In the formula: e is a mathematical transcendental number, e = 2.7182; When the height h of the annular boss is constant, the specific gap distance c1 of the radial sealing gap is constant, and the specific gap distance c2 of the axial sealing gap is constant, and the value range of the width b of the annular boss is: 2.6mm<b<4.4mm, the pressure resistance formula y2 of the labyrinth tower-shaped magnetic fluid sealing structure under different widths b of the annular boss is obtained: y2=-0.00129e 2.11216b +197.11743 (2.6<b<4.4) In the formula: e is a mathematical transcendental number, e = 2.7182; When the height h of the annular boss is constant, the width b of the annular boss is constant, and the specific gap distance c2 of the axial sealing gap is constant, and the specific gap distance c1 of the radial sealing gap has a value range of: 0.1mm<c1<1.2mm, the pressure resistance formula y3 of the maze tower-shaped magnetic fluid sealing structure under different specific gap distances c1 of the radial sealing gap is obtained: When the height h of the annular boss is constant, the width b of the annular boss is constant, the specific gap distance c1 of the radial sealing gap is constant, and the specific gap distance c2 of the axial sealing gap is in the range of 0.1 mm < c2 < 1.2 mm, the pressure resistance formula y4 of the maze tower-shaped magnetic fluid sealing structure under different specific gap distances c2 of the axial sealing gap is obtained:

6. A sealing performance test bench for a magnetic fluid sealing device based on a labyrinth tower, characterized in that: The invention comprises a magnetic fluid sealing device based on a labyrinth tower as claimed in any one of claims 1 to 5, and further comprises: Test bench; The spindle drive assembly includes a variable frequency motor arranged above the test bench through a motor bracket, wherein the output end of the variable frequency motor is connected to one end of the spindle through a coupling; A support assembly, comprising a seat bearing installed above the test bench, and the seat bearing is arranged on the main shaft for supporting the main shaft; A pressurizing component, comprising a sealing bracket for supporting the magnetic fluid sealing device, and a second sealing shell partially sleeved on the outside of the first sealing shell, wherein a mounting hole is provided in the middle of the sealing bracket for inserting and installing the first sealing shell of the magnetic fluid sealing device, and one side of the sealing bracket abuts against the extension of the first sealing shell; an annular flange is radially provided along the circumferential surface of one end of the second sealing shell, the annular flange is connected to the extension by bolts, and a constant pressure chamber is formed inside the second sealing shell; in addition, the pressurizing component also includes an air pump, which is connected in series with a pressure reducing valve and a throttle valve in sequence through a pipeline, and then connected to the constant pressure chamber through a preset sealing pressurizing hole on the second sealing shell; Detection components, including: The torque sensor is arranged on the coupling and is used to detect the torque provided by the variable frequency motor to the main shaft; A temperature sensor is provided inside the sealing pole shoe through a plurality of first detection holes, and is used to detect the temperature of the magnetic fluid inside the sealing gap when the main shaft rotates; The pressure sensor is arranged on the second sealed housing through the second detection hole, and is used for detecting the pressure inside the constant pressure cavity.

7. The sealing performance test bench for a magnetic fluid sealing device based on a labyrinth tower according to claim 6 is characterized in that: The test bench surface includes a load-bearing plate and a base arranged in a stepped manner from top to bottom. Both the load-bearing plate and the base are made of steel plates, and a number of rib plates are provided between the load-bearing plate and the base. In addition, a number of through holes and threaded holes are preset on the load-bearing plate for accurately positioning and installing the spindle drive assembly, the support assembly, and the pressurizing assembly.

8. The sealing performance test bench for a magnetic fluid sealing device based on a labyrinth tower according to claim 7 is characterized in that: In the support assembly, two bearing seats are provided, and each bearing seat is installed above the bearing plate through a support seat. On this basis, each bearing seat is interference fit with the main shaft.

9. The sealing performance test bench for a magnetic fluid sealing device based on a labyrinth tower according to claim 8 is characterized in that: On the basis that the pressurizing assembly and the magnetic fluid sealing device are installed in coordination, a fourth sealing ring is provided at the joint between the extension portion and the annular flange; In addition, the pressurizing component also includes a quick connector, which is arranged on the pipeline and is used to cooperate with the sealed pressurizing hole. In addition, the quick connector is a one-way connector that can only allow gas to be input from the air pump into the constant pressure chamber.

10. The sealing performance test bench for a magnetic fluid sealing device based on a labyrinth tower according to claim 9, characterized in that: In the detection assembly, the plurality of first detection holes are deep holes and are evenly distributed on the outer wall of the sealing bracket with the center of the main axis as the center of the circle. After the bottoms of the plurality of first detection holes pass through the first sealing shell, they are located inside the sealing pole shoe near the tower-shaped pole teeth. On this basis, a temperature sensor is arranged in each of the first detection holes. In addition, the detection component also includes a support platform for supporting the torque sensor, and the support platform is installed on a carrying plate.

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