Double-arch centrifugal pole tooth magnetic liquid sealing device

Abstract

The invention discloses a double-arch centrifugal pole tooth magnetic liquid sealing device, and belongs to the technical field of mechanical sealing. The sealing device is mainly composed of a sealing device structural part and a magnetic sealing body. A rotating shaft (12) is arranged in a cavity formed by a left end cover (1), a right end cover (10) and a sealing seat (2), the left end cover (1) and the right end cover (10) are fixedly connected with a base through bolts and nuts, a left bearing (3) and a right bearing (9) close to the left end cover and the right end cover are in interference connection with the rotating shaft (12) respectively, a magnetic sealing body structure is arranged in the sealing seat (2), and a left pole shoe (5) is fixed by a left shaft sleeve (4). A magnetic sleeve (11) is fixed to the right side of the right pole shoe (7), a permanent magnet (6) is installed between the left pole shoe and the right pole shoe and used for forming a sealed magnetic loop and causing the rheological effect of magnetic liquid, arch-shaped pole teeth (11) are machined at the top ends of the left pole shoe and the right pole shoe, and a semicircular annular protruding structure is machined on the surface of the rotating shaft (12). And a double-arch-shaped sealing gap formed by the protruding structure of the rotating shaft (12) and the arch-shaped pole teeth (12) is filled with magnetic liquid. According to the magnetic liquid sealing device, the double-arch centrifugal pole tooth design is adopted, rapidly-increased centrifugal force can be utilized at the high rotating speed, magnetic liquid is extruded towards the middle portion along the two sides of a double-arch gap to form a high-pressure area, magnetic fluid sealing and centrifugal pressure sealing are achieved at the same time, and the sealing effect is good. And the problem of sealing failure of a traditional magnetofluid seal under the high-rotating-speed working condition is solved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic liquid sealing, in particular to the principle and design method of a double-arch centrifugal pole tooth magnetic liquid sealing device, belonging to the technical field of mechanical sealing. Background Art

[0002] Magnetic fluid is a new type of intelligent fluid, mainly composed of base fluid and nano-magnetic particles suspended in the base fluid. When magnetic fluid is subjected to the working magnetic field, it will undergo rheological effects within milliseconds, reversibly transforming from liquid to quasi-solid state, with the characteristics of rapid response, long life and strong adaptability.

[0003] The magnetorheological sealing system uses magnetic liquid as the sealing medium. During the sealing process, the annular permanent magnet applies a magnetic field to the magnetic liquid placed between the rotating shaft and the top gap of the pole teeth, causing a rheological effect to form one or more "O-rings", thereby achieving the purpose of sealing. Magnetic liquid sealing technology is widely recognized as an advanced "zero leakage" dynamic sealing technology in countries around the world. Studies have shown that when the rotating shaft rotates at high speed, the centrifugal force on the magnetic liquid is greater than the magnetic field force, causing it to break away from the rotating shaft and squeeze toward the top of the pole teeth. In traditional sealing structures, the top of the pole teeth and the surface of the rotating shaft mostly use a planar structure, and the planar structure has no gathering force on the magnetic liquid. The magnetic liquid is very easy to escape from the top of the pole teeth, eventually causing the seal to fail.

[0004] At present, there are roughly three methods to improve the sealing performance of magnetic liquid: one is to use spring-loaded sealing, using spring force to maintain the contact between the seal and the sealing surface to maintain a continuous sealing effect; the second is to use multi-stage sealing, by setting multiple sealing points in the sealing system, the leakage of MR fluid can be effectively prevented; the third is to add surfactants, by adding surfactants, the aggregation between particles can be reduced, and the stability and sealing performance of MR fluid can be improved. Since the spring vibrates repeatedly during high-speed rotation and the spring has inertia and cannot stop moving immediately, the first method has low stability and short life; there are many ways to implement the second method; the third method requires high-quality surfactants, which are expensive, and due to the limited adsorption force of surfactants, it is not applicable to high-speed rotating objects (such as aircraft engines). After research and analysis, a new magnetic liquid body sealing structure is designed. Without adding additional mechanisms, the contact part of the magnetic liquid and the shaft is improved in terms of mechanism design. The double arch mechanism can reduce the pressure and axial normal stress, so that the magnetic liquid seal is firm and still has high stability under high speed conditions.

[0005] Through patent search, the following known technical solutions exist: application number is CN202111153987.7, application date: 2021.09.29, authorization announcement date: 2022.04.26. This patent relates to an embedded sleeve-type magnetic liquid sealing device, which forms a structure similar to a labyrinth seal by embedding a sleeve with pole teeth between the pole shoes. At the same time, a non-magnetic conductive shaft is used to enhance the magnetic field of the sealing gap, which can have better sealing pressure resistance under the condition of eccentric shaft and high speed.

[0006] The device takes into account the problem of shaft eccentricity caused by assembly errors, vibrations, and other factors, and reduces the impact of eccentricity through a labyrinth seal design with staggered pole teeth; however, its outer end bevel design can only reduce the loss of magnetic fluid at high speeds, and cannot fully solve the problem of seal failure caused by high-speed centrifugal force.

[0007] Through patent search, there are the following known technical solutions: Application number: CN117386818A, application date: 2023.11.13, authorization announcement date: 2024.01.12. The present invention relates to a step tower type pole tooth magnetic liquid sealing device. It mainly solves the technical problem of poor stability of magnetic liquid sealing in high-pressure and high-speed occasions in existing magnetic liquid seals. The technical solution adopted by the present invention is: a step tower type pole tooth magnetic liquid sealing device, which includes a rotating shaft, an end cover, a left pole shoe, a permanent magnet, a right pole shoe, a shell and a magnetic liquid, the left pole shoe, the permanent magnet and the right pole shoe are sequentially installed side by side in the axial direction in the chamber of the shell; a plurality of step tower type pole teeth are provided on the inner circumference of the left pole shoe and the right pole shoe, the rotating shaft passes through the pole tooth holes of the left pole shoe and the right pole shoe and can rotate, and the gap formed by the step tower type pole tooth and the rotating shaft is filled with magnetic liquid to play a sealing role. The present invention can protect the magnetic liquid sealing film from being easily squeezed and damaged by the stepped tower-shaped pole teeth, thereby improving the stability of the magnetic liquid seal and extending the sealing life.

[0008] The device does not fully consider the high-speed centrifugal effect and adopts a vertical step structure. The magnetic liquid is easily separated from the rotating shaft due to the centrifugal force, and the sealing performance is limited under the condition of high-speed operation of the rotating shaft.

[0009] Through the above search, it is found that the above technical solutions do not affect the novelty of the present invention; and the mutual combination of the above patent documents does not destroy the creativity of the present invention. Summary of the invention

[0010] In view of the above problems, the present invention discloses a double-arch centrifugal pole gear magnetic liquid sealing device, which aims to solve the problem of centrifugal loss and sealing failure of magnetic liquid when the rotating shaft rotates at high speed. The actuator has the following advantages: (1) small structure size; (2) having both magnetic fluid sealing and centrifugal sealing characteristics; (3) extremely fast response speed, almost zero; (4) mature manufacturing process and simple and easy working principle; (5) reliable operation and strong applicability.

[0011] The objective of the present invention is achieved through the following technical solutions:

[0012] The invention discloses a double-arch centrifugal pole tooth magnetic liquid sealing device, which mainly consists of a sealing device structural part and a magnetic sealing body. The sealing device structural part comprises a right end cover (10), a left end cover (1), a nut, a sealing seat (2), a left bearing (3), a right bearing (9), and a rotating shaft (12). The rotating shaft (12) is placed in a cavity formed by the left end cover (1), the right end cover (10) and the sealing seat (2); the magnetic sealing body part comprises a left pole shoe (5), a right pole shoe (7), a left shaft sleeve (4), a permanent magnet (6), a magnetic sleeve (8) and an arch pole tooth (11). The surface of the rotating shaft (12) is processed with a semicircular annular protrusion structure, and magnetic liquid is filled in the double-arch gap formed by the arch pole tooth (11) and the rotating shaft protrusion structure (12). A permanent magnet (6) is placed between the left pole shoe (5) and the right pole shoe (7).

[0013] In the double-arch centrifugal pole tooth magnetic liquid sealing device described in the present invention, the magnetic field generated by the permanent magnet causes the magnetic liquid therein to have a rheological effect. Under the high-speed centrifugal action of the rotating shaft, the magnetic liquid gradually flows from the rotating shaft to the arched pole teeth. Since the arched pole teeth have a gathering effect on the arc structure of the magnetic liquid, the magnetic liquid is squeezed from both sides of the double-arch gap to the middle to form a high-pressure area, thereby improving the pressure resistance of the seal.

[0014] Beneficial Effects

[0015] 1. The present invention is based on a magnetic liquid sealing system with a double-arch structure. When there is a pressure difference at both ends of the magnetic liquid and the shaft is in a high-speed rotation process, due to the centrifugal effect, the magnetic liquid flows toward the arched pole teeth and is squeezed toward the middle along both sides of the double-arch gap to form a high-pressure area, thereby improving the pressure resistance of the magnetic liquid seal.

[0016] 2. The present invention discloses a magnetic liquid sealing system with a double-arch structure. The higher the working speed of the rotating shaft, the stronger the aggregation effect of the magnetic liquid in the double-arch gap, the greater the centrifugal pressure in the middle of the sealing gap, and the stronger the sealing ability.

[0017] 3. The present invention is based on a magnetic liquid sealing system with a double-arch structure. At low speeds, the centrifugal force is small and traditional magnetic liquid seals are used to achieve zero leakage. At high speeds, the centrifugal force increases sharply and the double-arch sealing gap is used to form a centrifugal pressure seal, thereby compensating for the sealing failure problem of traditional magnetic fluid seals under high speed conditions.

[0018] 4. Magnetic liquid produces rheological effect under the action of magnetic field. Since this invention directly improves the axial mechanism and eliminates the response process, the response speed is fast, which is in milliseconds.

[0019] 5. Compared with the traditional fluid sealing invention, the present invention has a small volume, a simple and compact structure, low processing difficulty, and is suitable for miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the overall structure of a double-arch centrifugal pole tooth magnetic liquid sealing device.

[0021] Among them: 1-left end cover, 2-sealing seat, 3-left bearing, 4-left shaft sleeve, 5-left pole shoe, 6-permanent magnet, 7-right pole shoe, 8-magnetic sleeve, 9-right bearing, 10-right end cover, 11-pole tooth, 12-rotating shaft.

[0022] Figure 2 The present invention is a structural diagram of the pole teeth and rotating shaft of a double-arch centrifugal pole tooth magnetic liquid sealing device.

[0023] Wherein: 11-pole teeth, 12-rotating shaft, 13-magnetic liquid. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0025] Embodiment 1:

[0026] This embodiment is a double arch centrifugal pole gear magnetic liquid sealing device. Figure 1 As shown. It mainly consists of two parts: magnetic liquid rotating parts and permanent magnets.

[0027] The left end cover (1) and the right end cover (10) are connected and fixed to the base by bolts and nuts. Near the left and right end covers, there are left bearings (3) and right bearings (9) respectively connected to the rotating shaft (12) by interference fit. The sealing seat (2) is equipped with a magnetic sealing body structure, wherein the left pole shoe (5) is fixed by the left shaft sleeve (4), and the right side of the right pole shoe (7) is fixed with a magnetic sleeve (11). The tops of the left and right pole shoes are both processed with arched pole teeth (11), and the surface of the rotating shaft (12) is processed with a semicircular annular protrusion structure. The double arched sealing gap formed by the protrusion structure of the rotating shaft (12) and the arched pole teeth (12) is filled with magnetic liquid. A permanent magnet (6) is installed between the left and right pole shoes to form a sealed magnetic circuit, causing the magnetic liquid to have a rheological effect.

[0028] The left pole shoe (5) and the right pole shoe (7) adopt a structure of multiple parallel arched pole teeth (11) and a multi-layer design to achieve a better sealing effect. Under the high-speed centrifugal action of the rotating shaft, the magnetic liquid gradually flows from the rotating shaft to the arched pole teeth. Since the arched pole teeth have a gathering effect on the arc structure of the magnetic liquid, the magnetic liquid is squeezed from both sides of the double arched gap to the middle, forming a high-pressure area and a centrifugal pressure sealing effect, thereby improving the sealing pressure resistance of the system.

[0029] Finally, it should be noted that the specific description described above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail, with the aim of helping to further understand the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A double-arch centrifugal pole gear magnetic liquid sealing device, characterized in that: The magnetic liquid sealing system comprises: a sealing device structural component and a magnetic sealing body; the sealing device structural component comprises a left end cover (1), a right end cover (10), bolts, nuts, a sealing seat (2), a left bearing (3), a right bearing (9), and a rotating shaft (12); the inner sides of the left end cover (1) and the right end cover (10) respectively have a left bearing (3) and a right bearing (9) which are interference-connected with the rotating shaft (12); the rotating shaft (12) is disposed in a cavity formed by the left end cover (1), the right end cover (10) and the sealing seat (2); the magnetic sealing body comprises a left pole shoe (5), a right pole shoe ( 7), a left shaft sleeve (4), a permanent magnet (6), a magnetic sleeve (8) and an arched pole tooth (11), a permanent magnet (6) is installed between the left and right pole shoes to form a sealed magnetic circuit, the left pole shoe (5) is fixed by the left shaft sleeve (4), the magnetic sleeve (8) is fixed to the right end of the right bearing (9), the top ends of the left pole shoe (5) and the right pole shoe (6) are both processed with an arched pole tooth (11), the surface of the rotating shaft (12) is processed with a semicircular annular protrusion structure, and a magnetic liquid is filled in the double arched sealing gap formed by the protrusion structure of the rotating shaft (12) and the arched pole tooth (12).

2. A double-arch centrifugal pole tooth magnetic liquid sealing device according to claim 1, characterized in that: The pole teeth on the pole shoe adopt an arched structure, and a semicircular annular protrusion structure is processed on the rotating shaft. The processing position is the annular area covered by the cross section of the pole teeth projected onto the rotating shaft. The two arched structures are coaxial and face the same side, forming a double-arched sealing gap.

3. A double-arch centrifugal pole tooth magnetic liquid sealing device according to claim 1, characterized in that: Under the high-speed centrifugal action of the rotating shaft, the magnetic liquid flows from the rotating shaft to the arched pole teeth. Since the arched pole teeth have a gathering effect on the arc structure of the magnetic liquid, the magnetic liquid is squeezed from both sides of the double-arched gap to the middle to form a high-pressure area, achieving a centrifugal pressure sealing effect, thereby improving the pressure resistance of the seal; the higher the working speed of the rotating shaft, the stronger the gathering effect of the magnetic liquid in the double-arched gap, the greater the centrifugal pressure in the middle of the sealing gap, and the stronger the sealing ability.

4. A double-arch centrifugal pole tooth magnetic liquid sealing device according to claim 1, characterized in that: At low speeds, the centrifugal force of the rotating shaft is small, and the sealing system uses traditional magnetic liquid sealing to achieve zero leakage. At high speeds, the centrifugal force of the rotating shaft increases sharply, and the double-arch centrifugal pole tooth magnetic liquid sealing device uses a double-arch sealing gap to form a centrifugal pressure seal, thereby compensating for the sealing failure problem of traditional magnetic fluid seals under high speed conditions.

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