A magnetic levitation magnetohydrodynamic sealing device

Abstract

This invention discloses a magnetic levitation magnetofluid sealing device, comprising a main shaft, an insulating bushing, an outer ring of the bushing, and a magnetic levitation module. The outer ring of the bushing includes a connecting part, a flexible component, and a third permanent magnet. The magnetic levitation module includes first and second magnetic levitation units, each containing a second permanent magnet and first permanent magnets at both axial ends, with a magnetic shielding plate and pole shoes between them. The pole teeth and the third permanent magnet form a sealing gap and are filled with magnetofluid. When the main shaft vibrates, causing the outer ring of the bushing to vibrate, the flexible component first undergoes elastic deformation to absorb vibration energy, reducing the tilt amplitude of the outer ring of the bushing. When the outer ring of the bushing vibrates and causes left and right swaying, the component closer to one side will receive a repulsive force from the same pole, thus resisting the vibration and preventing the third permanent magnet from getting too close to the pole teeth, reducing the distance between the third permanent magnet and the pole teeth and pole shoes. This invention, through a dual mechanism of flexible vibration absorption and dynamic balance of magnetic repulsion, prevents magnetofluid leakage or even seal failure caused by the main shaft vibration colliding with the sealing component.

Description

Technical Field

[0001] This invention relates to the field of mechanical seal technology, and more particularly to a magnetic levitation magnetohydrodynamic sealing device. Background Technology

[0002] The turbine is the core equipment for hydroelectric energy conversion. Its main shaft, as a key component for power transmission, is subjected to enormous hydraulic impact and mechanical torque during operation. When the unit enters a non-optimal operating range, especially during low-load operation or transition processes, the strong hydraulic imbalance can induce severe radial vibration of the main shaft. Under this vibration condition, the main shaft makes direct metallic contact with the tip of the pole teeth, generating a huge instantaneous impact force. This not only leaves wear marks on the high-hardness surface of the pole teeth, but more importantly, the huge shear force directly scrapes, peels off, and throws the magnetic fluid adhering to the pole teeth out of the sealing gap. This causes the shaft center position to drift violently and irregularly within the sealing cavity, ultimately leading to seal leakage or even complete failure.

[0003] Existing sealing technologies mainly include the following categories:

[0004] The first type is traditional contact seals, such as packing seals and lip seals. Their fundamental flaw lies in their inability to adapt to dynamic gap changes. When spindle vibration causes the gap to decrease instantaneously, the seal rubs violently against the spindle, generating high temperatures and accelerating wear, potentially leading to seal burnout and spindle damage. Conversely, when the gap increases instantaneously, insufficient sealing pressure can cause significant leakage in a short period. Essentially, this type of seal relies on self-wearing to maintain a seal, a passive and sacrificial solution that cannot fundamentally address the problem of dynamic gap changes. The second type is non-contact seals, such as labyrinth seals. Their design is based on a fixed gap, and the sealing effect is inversely proportional to the gap value. Even minor vibrations causing a gap increase can lead to an exponential increase in leakage. Furthermore, labyrinth seals themselves do not provide any damping and have no effect on inhibiting spindle vibration; in fact, they may exacerbate vibration due to fluid forces. Under severe vibration, the sealing teeth may rub against the spindle, and once damaged, the sealing performance will permanently deteriorate. The third type is active / semi-active control seals, whose fundamental drawbacks lie in system complexity, poor reliability, and high cost. This solution requires sensors to detect vibration or gap changes, which are then processed by the controller and acted upon by the actuator. The response speed may not keep up with high-frequency or transient vibrations, and additional sensing, control, and power systems are required. The failure rate increases significantly in harsh environments with humidity and vibration, and the technical requirements for on-site maintenance personnel are high, resulting in maintenance costs far exceeding those of traditional seals. Furthermore, traditional structural designs generally pursue rigidity and stability, attempting to suppress vibration by increasing stiffness. However, this is often ineffective against strong external excitations such as hydraulic vibration, and it also increases equipment weight and cost. At the same time, the wear resistance, elastic recovery, and anti-aging properties of sealing materials such as rubber and polyurethane often cannot simultaneously meet all the requirements under dynamic operating conditions. The hardness and toughness of the wear-resistant coating on the spindle are difficult to balance, and peeling is prone to occur under dynamic impact and wear.

[0005] In summary, existing sealing technologies cannot effectively solve the technical problem of excessive dynamic changes in sealing gaps caused by irregular vibrations during high-speed operation of turbine main shafts, which leads to scraping and peeling of the magnetofluid, sealing leakage, or even failure. Therefore, there is an urgent need for a new type of sealing device that can adapt to dynamic gap changes, actively suppress the effects of vibration, and has a simple and reliable structure. Summary of the Invention

[0006] This invention provides a magnetic levitation magnetohydrodynamic sealing device to solve the technical problem that existing sealing devices cannot effectively solve the problem of excessive dynamic changes in the sealing gap caused by irregular vibration of the turbine main shaft during high-speed operation, which leads to sealing leakage or even failure.

[0007] In view of the above technical problems, the present invention provides a magnetic levitation magnetohydrodynamic sealing device, including a main shaft, an insulating bushing sleeved on the outer periphery of the main shaft, an outer ring of the bushing sleeve connected to the insulating bushing sleeve, and magnetic levitation modules symmetrically arranged on both sides of the outer ring of the bushing sleeve; the outer ring of the bushing sleeve includes a connecting part connected to the insulating bushing sleeve, a flexible component connected to the connecting part, and a third permanent magnet connected to the flexible component;

[0008] The magnetic levitation module includes a first magnetic levitation unit and a second magnetic levitation unit symmetrically arranged on both sides of the outer ring of the bushing. The first magnetic levitation unit and the second magnetic levitation unit each include a second permanent magnet and a first permanent magnet disposed at both ends of the axial direction of the second permanent magnet. A magnetic shielding plate and a pole shoe are also disposed sequentially between each first permanent magnet and the second permanent magnet. The upper section of the third permanent magnet is the N pole and the lower section is the S pole.

[0009] In the first magnetic levitation unit, the upper section of the second permanent magnet is the N pole and the lower section is the S pole; the left end of the first permanent magnet connected to the first end of the second permanent magnet is the S pole and the right end is the N pole; the left end of the first permanent magnet connected to the second end of the second permanent magnet is the N pole and the right end is the S pole.

[0010] In the second magnetic levitation unit, the upper section of the second permanent magnet is the N pole and the lower section is the S pole; the left end of the first permanent magnet connected to the first end of the second permanent magnet is the N pole and the right end is the S pole; the left end of the first permanent magnet connected to the second end of the second permanent magnet is the S pole and the right end is the N pole.

[0011] A pole tooth is provided on the inner side of the pole shoe near the third permanent magnet. The pole tooth forms a sealing gap with the outer peripheral surface of the third permanent magnet. The sealing gap is filled with a magnetic fluid body, and the magnetic fluid body is located in the middle section of the third permanent magnet.

[0012] When the main shaft vibrates radially, the flexible component deforms to absorb the vibration energy. At the same time, a dynamic magnetic force of like poles repulsion is generated between the end of the third permanent magnet and the first permanent magnet on the corresponding side, forming a dynamic balance to prevent the third permanent magnet from getting too close to the pole tooth.

[0013] Optionally, the sealing gap where the magnetofluid body is located is situated in the weakest region of the magnetic field in the middle section of the third permanent magnet, so as to avoid the magnetic field of the third permanent magnet interfering with the magnetic field of the second permanent magnet.

[0014] Optionally, the third permanent magnet is made of samarium cobalt permanent magnet material.

[0015] Optionally, the magnetic levitation magnetohydrodynamic sealing device further includes a bearing end cover, a ball bearing, and a sealing housing. The bearing end cover is disposed at the end of the main shaft, and the ball bearing is used to support the rotation of the main shaft. The sealing housing is fixedly connected to the bearing end cover by hexagonal head bolts.

[0016] The present invention has the following beneficial effects:

[0017] First, this invention significantly improves the sealing system's tolerance to radial vibration of the main shaft. The flexible component first undergoes elastic deformation during vibration, absorbing vibration energy and reducing the tilt amplitude of the outer ring of the bushing, preventing rigid collisions between the third permanent magnet and the pole teeth, thus allowing the main shaft to operate stably within a wider range of radial vibration. Second, it achieves non-contact dynamic gap self-adjustment. Utilizing the principle of like pole repulsion between the end of the third permanent magnet and the first permanent magnet, when the outer ring of the bushing tilts towards either side, the near-side air gap decreases, leading to a significant increase in repulsive force, while the far-side air gap increases, resulting in a corresponding decrease in repulsive force. Under the action of this strong-weak repulsive force difference, a net restoring force pointing to the far side is formed, allowing the outer ring of the bushing to automatically maintain a dynamic equilibrium position between magnetic force and vibration force. This mechanism requires no additional sensors, controllers, or actuators, has a fast response speed, and high reliability, fundamentally solving the technical problem that traditional sealing devices cannot adapt to dynamic gap changes. Third, this invention enables the turbine to operate at higher speeds. Traditional sealing devices limit the maximum operating speed of turbines due to vibration constraints. This invention effectively suppresses the impact of vibration on the sealing gap through a magnetic levitation dynamic balancing mechanism, eliminating the sealing bottleneck at higher speeds and enabling the equipment to operate safely and stably at higher speeds, thus improving the power generation efficiency and operational flexibility of the turbine unit. Fourth, this invention extends the service life of the sealing device and reduces maintenance costs. It avoids direct metallic contact between the shaft and the pole teeth, eliminating the root cause of wear marks on the pole tooth surface and scraping and peeling of the magnetic fluid, reducing magnetic fluid loss and the frequency of seal replacement. Simultaneously, the system has a simple structure, requiring no complex active control components, and exhibits higher reliability and a lower failure rate in the harsh operating environment of humid and vibrating turbines, significantly reducing the technical requirements and maintenance costs for on-site maintenance personnel. Fifth, it ensures the stability of the magnetic fluid sealing magnetic field by placing the magnetic fluid body in the weakest magnetic field region of the middle section of the third permanent magnet. This prevents the magnetic field of the third permanent magnet from excessively interfering with the magnetic fluid sealing magnetic field provided by the second permanent magnet, ensuring stable filling of the magnetic fluid in the sealing gap and long-term reliable sealing performance. Sixth, this invention improves the durability of materials in harsh environments. The third permanent magnet uses samarium cobalt permanent magnet material, which has high magnetism, high coercivity, excellent corrosion resistance and oxidation resistance. It can maintain its magnetism for a long time in complex environments such as high temperature and magnetic fluids, air and liquids, avoid demagnetization, and ensure the long-term effective operation of the magnetic levitation dynamic balance mechanism. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of a magnetic levitation magnetic fluid sealing device in one embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the polarity structure of the magnetic levitation module of the magnetic levitation magnetic fluid sealing device in one embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram illustrating the working principle of a magnetic levitation magnetohydrodynamic sealing device according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the working principle of the magnetic levitation magnetic fluid sealing device in another embodiment of the present invention.

[0023] The reference numerals in the accompanying drawings are as follows:

[0024] 1-Main shaft, 2-Insulating bushing, 3-Bearing end cover, 4-Ball bearing, 5-Hexagonal head bolt, 6-Sealed housing, 7-First permanent magnet, 8-Magnetic shielding plate, 9-Second permanent magnet, 10-Pole shoe, 11-Pole tooth, 12-Magnetic fluid body, 13-Flexible component, 14-Third permanent magnet, 15-Connecting part. Detailed Implementation

[0025] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] In the description of this invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] like Figures 1 to 2 As shown, an embodiment of the present invention provides a magnetic levitation magnetohydrodynamic sealing device, including a main shaft 1, an insulating bushing 2 sleeved on the outer periphery of the main shaft 1, an outer ring of the bushing connected to the insulating bushing 2, and magnetic levitation modules symmetrically arranged on both sides of the outer ring of the bushing; the outer ring of the bushing includes a connecting part 15 connected to the insulating bushing 2, a flexible component 13 connected to the connecting part 15, and a third permanent magnet 14 connected to the flexible component 13;

[0029] The magnetic levitation module includes a first magnetic levitation unit and a second magnetic levitation unit symmetrically arranged on both sides of the outer ring of the bushing. The first magnetic levitation unit and the second magnetic levitation unit each include a second permanent magnet 9 and a first permanent magnet 7 disposed at both ends of the axial direction of the second permanent magnet 9. A magnetic shielding plate 8 and a pole shoe 10 are also arranged sequentially between each first permanent magnet 7 and the second permanent magnet 9. The upper section of the third permanent magnet 14 is the N pole and the lower section is the S pole.

[0030] In the first magnetic levitation unit, the upper section of the second permanent magnet 9 is the N pole and the lower section is the S pole; the left end of the first permanent magnet 7 connected to the first end of the second permanent magnet 9 is the S pole and the right end is the N pole; the left end of the first permanent magnet 7 connected to the second end of the second permanent magnet 9 is the N pole and the right end is the S pole.

[0031] In the second magnetic levitation unit, the upper section of the second permanent magnet 9 is the N pole and the lower section is the S pole; the left end of the first permanent magnet 7 connected to the first end of the second permanent magnet 9 is the N pole and the right end is the S pole; the left end of the first permanent magnet 7 connected to the second end of the second permanent magnet 9 is the S pole and the right end is the N pole.

[0032] A pole tooth 11 is provided on the inner side of the pole shoe 10 near the third permanent magnet 14. The pole tooth 11 and the outer peripheral surface of the third permanent magnet 14 form a sealing gap. The sealing gap is filled with a magnetic fluid body 12, and the magnetic fluid body 12 is located in the middle section of the third permanent magnet 14.

[0033] When the main shaft 1 generates radial vibration, the flexible component 13 deforms to absorb the vibration energy. At the same time, the end of the third permanent magnet 14 and the first permanent magnet 7 on the corresponding side generate a dynamic magnetic force of like poles repulsion, forming a dynamic balance to prevent the third permanent magnet 14 from getting too close to the pole tooth 11.

[0034] Understandably, the magnetic levitation magnetohydrodynamic sealing device of the present invention includes a main shaft 1, an insulating bushing 2 sleeved on the outer periphery of the main shaft 1, an outer ring of the bushing connected to the insulating bushing 2, and magnetic levitation modules symmetrically arranged on both sides of the outer ring of the bushing. The outer ring of the bushing includes a connecting part 15, a flexible component 13, and a third permanent magnet 14. The connecting part 15 is connected to the outer peripheral surface of the insulating bushing 2; the flexible component 13 is connected to the outer periphery of the connecting part 15; the third permanent magnet 14 is connected to the outer periphery of the flexible component 13, and the upper section of the third permanent magnet 14 is the N pole and the lower section is the S pole.

[0035] The magnetic levitation module is composed of an outer ring bushing and first permanent magnets 7 symmetrically arranged on both sides of it. Specifically, the magnetic levitation module includes a first magnetic levitation unit and a second magnetic levitation unit symmetrically arranged on both sides of the outer ring bushing; each magnetic levitation unit includes a second permanent magnet 9 and first permanent magnets 7 disposed at both axial ends of the second permanent magnet 9. A magnetic shielding plate 8 and a pole shoe 10 are also sequentially disposed between each first permanent magnet 7 and the second permanent magnet 9. A pole tooth 11 is disposed on the inner side of the pole shoe 10 near the third permanent magnet 14. The pole tooth 11 and the outer peripheral surface of the third permanent magnet 14 form a sealing gap, which is filled with a magnetic fluid body 12, and the magnetic fluid body 12 is located in the middle section of the third permanent magnet 14.

[0036] Understandably, to achieve the magnetic levitation effect, the first permanent magnet 7 is not directly connected to the outer ring of the bushing, but the first permanent magnets 7 on both sides of the outer ring of the bushing must generate like magnetic fields with the third permanent magnet 14 to form a repulsive force. In the first magnetic levitation unit, the upper section of the second permanent magnet 9 is the N pole and the lower section is the S pole; the left end of the first permanent magnet 7 connected to the first end of the second permanent magnet 9 is the S pole and the right end is the N pole; the left end of the first permanent magnet 7 connected to the second end of the second permanent magnet 9 is the N pole and the right end is the S pole. In the second magnetic levitation unit, the upper section of the second permanent magnet 9 is the N pole and the lower section is the S pole; the left end of the first permanent magnet 7 connected to the first end of the second permanent magnet 9 is the N pole and the right end is the S pole; the left end of the first permanent magnet 7 connected to the second end of the second permanent magnet 9 is the S pole and the right end is the N pole. Through the above magnetic pole arrangement, the left and right sides of the upper N pole and lower S pole of the third permanent magnet 14 both have magnetic fields with the same polarity. Due to the repulsion of like poles, the magnetic levitation effect is achieved.

[0037] In one embodiment, such as Figure 1 and Figure 2As shown, the sealing gap where the magnetofluid body 12 is located is in the weakest magnetic field region in the middle section of the third permanent magnet 14, so as to avoid the magnetic field of the third permanent magnet 14 interfering with the magnetic field of the second permanent magnet 9.

[0038] In one embodiment, such as Figure 1 and Figure 2 As shown, the third permanent magnet 14 is made of samarium cobalt permanent magnet material.

[0039] In one embodiment, such as Figure 1 and Figure 2 As shown, the magnetic levitation magnetohydrodynamic sealing device also includes a bearing end cover 3, a ball bearing 4, and a sealing housing 6. The bearing end cover 3 is disposed at the end of the main shaft 1, and the ball bearing 4 is used to support the rotation of the main shaft 1. The sealing housing 6 is fixedly connected to the bearing end cover 3 by hexagonal head bolts 5.

[0040] Understandably, the present invention reduces the vibration of the magnetic levitation module caused by the high-speed rotation of the main shaft by transforming the traditional axially sealed main shaft into a radially sealed magnetic levitation module, and by making the magnetic levitation module composed of two materials with different functions (a first permanent magnet 7 and a second permanent magnet 9), thereby achieving the purpose of allowing the radial vibration of the turbine main shaft to increase and allowing the turbine to operate at a higher speed.

[0041] When the main shaft 1 vibrates due to high-speed rotation, the insulating bushing 2 and its outer ring will also vibrate. At this time, the flexible component 13 on the outer ring of the bushing will deform first, on the one hand preventing the outer ring of the bushing from breaking due to direct collision with the sealing part caused by vibration, and on the other hand absorbing vibration energy to reduce the vibration amplitude of the outer ring of the bushing. At the same time, the metal part of the outer ring of the bushing, namely the third permanent magnet 14, also vibrates. The upper section of the third permanent magnet 14 is the N pole and the lower section is the S pole. The sealing gap where the magnetofluid body 12 is located is in the middle section of the third permanent magnet 14. Since the magnetism is weakest in the middle section of a magnet, the magnetic field of the third permanent magnet 14 itself will not be too large to affect the magnetic field of the second permanent magnet 9, thereby ensuring the stability of the magnetofluid seal.

[0042] Since the third permanent magnet 14 is always in a complex magnetic field environment, there are magnetic fields of the same polarity on both its left and right sides. When the vibration causes the outer ring of the bushing to tilt and approach in a certain direction, the repulsive force between the end of the third permanent magnet 14 and the first permanent magnet 7 on the corresponding side increases as the distance decreases, while the repulsive force on the side further away decreases accordingly. Under the action of the difference between strong and weak repulsive forces, a dynamic balance is formed, preventing the third permanent magnet 14 from getting too close to the pole shoe 10 and the pole tooth 11, and preventing collision damage to the sealing equipment.

[0043] Furthermore, since the third permanent magnet 14 is exposed to a complex environment of magnetofluids, air, and liquids for extended periods, it requires strong magnetism and high coercivity to maintain its magnetism and prevent demagnetization. It also needs to possess certain corrosion resistance and oxidation resistance. Taking all factors into consideration, the third permanent magnet 14 is preferably made of samarium cobalt permanent magnet material. Samarium cobalt is a high-performance rare-earth permanent magnet material, whose outstanding characteristic is that it can maintain excellent magnetic properties even under high temperatures and harsh environments, and it does not require electroplating.

[0044] like Figure 3 As shown, when the main shaft 1 vibrates radially due to hydraulic imbalance and moves towards... Figure 3 When the spindle 1 tilts in direction B, the insulating bushing 2 and the outer ring of the bushing (including the connecting part 15, the flexible component 13, and the third permanent magnet 14) tilt synchronously. At this time, the outer ring of the bushing moves closer to the second magnetic levitation unit on side B and away from the first magnetic levitation unit on side A. If the amplitude exceeds the allowable range, the third permanent magnet 14 will directly collide with the pole shoe 10 and pole teeth 11 on side B, causing the sealing gap to be destroyed, the magnetofluid body 12 to be squeezed and peeled off, and ultimately causing the seal to fail. In this case, the present invention prevents the above-mentioned collision from occurring through the following dual mechanism:

[0045] First, the vibration absorption deformation mechanism of the flexible component 13. When the outer ring of the bushing tilts, the flexible component 13 first undergoes elastic deformation, absorbing part of the vibration energy, reducing the tilt amplitude of the outer ring of the bushing, and preventing the third permanent magnet 14 from rigidly colliding with the pole shoe 10 and the pole tooth 11.

[0046] Second, the magnetic levitation dynamic balance mechanism. When the outer ring of the bushing moves closer to side B, the air gap between the third permanent magnet 14 and the first permanent magnet 7 of the second magnetic levitation unit on side B decreases. According to the principle of like poles repulsion, the magnetic repulsion between them increases significantly as the distance decreases. At the same time, the air gap between the third permanent magnet 14 and the first permanent magnet 7 of the first magnetic levitation unit on side A increases, and the corresponding repulsion weakens. Under the combined effect of the increased repulsion on side B and the decreased repulsion on side A, a net restoring force pointing towards side A is generated, causing the outer ring of the bushing to be subjected to a reverse thrust, thereby preventing it from continuing to approach the pole shoe 10 and pole tooth 11 on side B, forming a dynamic balance. Through the dual effects of the above-mentioned flexible vibration absorption and the dynamic balance of magnetic repulsion, the outer ring of the bushing always maintains a relative balance position between the magnetic force and the vibration force, effectively reducing the impact of vibration on the sealing device, ensuring the stable filling of the magnetofluid body 12 in the sealing gap, and preventing seal failure.

[0047] like Figure 4 As shown, when the main shaft 1 vibrates radially due to hydraulic imbalance and moves towards... Figure 4When the spindle 1 tilts in direction A, the insulating bushing 2 and the outer ring of the bushing (including the connecting part 15, the flexible component 13, and the third permanent magnet 14) tilt synchronously. At this time, the outer ring of the bushing moves closer to the first magnetic levitation unit on side A and away from the second magnetic levitation unit on side B. If the amplitude exceeds the allowable range, the third permanent magnet 14 will directly collide with the pole shoe 10 and pole teeth 11 on side A, causing the sealing gap to be destroyed, the magnetofluid body 12 to be squeezed and peeled off, and ultimately causing the seal to fail. In this case, the present invention prevents the above-mentioned collision from occurring through the following dual mechanism:

[0048] First, the vibration absorption deformation mechanism of the flexible component 13. When the outer ring of the bushing tilts, the flexible component 13 first undergoes elastic deformation, absorbing part of the vibration energy, reducing the tilt amplitude of the outer ring of the bushing, and preventing the third permanent magnet 14 from rigidly colliding with the pole shoe 10 and the pole tooth 11.

[0049] Second, the magnetic levitation dynamic balance mechanism. When the outer ring of the bushing moves closer to side A, the air gap between the third permanent magnet 14 and the first permanent magnet 7 of the first magnetic levitation unit on side A decreases. According to the principle of like poles repulsion, the magnetic repulsion between them increases significantly as the distance decreases. At the same time, the air gap between the third permanent magnet 14 and the first permanent magnet 7 of the second magnetic levitation unit on side B increases, and the corresponding repulsion weakens. Under the combined effect of the increased repulsion on side A and the decreased repulsion on side B, a net restoring force pointing towards side B is generated, causing the outer ring of the bushing to be subjected to a reverse thrust, thereby preventing it from continuing to approach the pole shoe 10 and pole tooth 11 on side A, forming a dynamic balance. Through the dual effects of the above-mentioned flexible vibration absorption and the dynamic balance of magnetic repulsion, the outer ring of the bushing always maintains a relative balance position between the magnetic force and the vibration force, effectively reducing the impact of vibration on the sealing device, ensuring the stable filling of the magnetofluid body 12 in the sealing gap, and preventing seal failure.

[0050] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A magnetic levitation magnetohydrodynamic sealing device, characterized in that, It includes a main shaft (1), an insulating bushing (2) sleeved on the outer periphery of the main shaft (1), an outer ring of the bushing connected to the insulating bushing (2), and magnetic levitation modules symmetrically arranged on both sides of the outer ring of the bushing; the outer ring of the bushing includes a connecting part (15) connected to the insulating bushing (2), a flexible component (13) connected to the connecting part (15), and a third permanent magnet (14) connected to the flexible component (13); The magnetic levitation module includes a first magnetic levitation unit and a second magnetic levitation unit symmetrically arranged on both sides of the outer ring of the bushing. The first magnetic levitation unit and the second magnetic levitation unit each include a second permanent magnet (9) and a first permanent magnet (7) disposed at both ends of the axial direction of the second permanent magnet (9). A magnetic shielding plate (8) and a pole shoe (10) are also arranged sequentially between each first permanent magnet (7) and the second permanent magnet (9). The upper section of the third permanent magnet (14) is the N pole and the lower section is the S pole. In the first magnetic levitation unit, the upper section of the second permanent magnet (9) is the N pole and the lower section is the S pole; the left end of the first permanent magnet (7) connected to the first end of the second permanent magnet (9) is the S pole and the right end is the N pole; the left end of the first permanent magnet (7) connected to the second end of the second permanent magnet (9) is the N pole and the right end is the S pole. The upper section of the second permanent magnet (9) in the second magnetic levitation unit is the N pole and the lower section is the S pole; the left end of the first permanent magnet (7) connected to the first end of the second permanent magnet (9) is the N pole and the right end is the S pole; the left end of the first permanent magnet (7) connected to the second end of the second permanent magnet (9) is the S pole and the right end is the N pole. A pole tooth (11) is provided on the inner side of the pole shoe (10) near the third permanent magnet (14). The pole tooth (11) and the outer peripheral surface of the third permanent magnet (14) form a sealing gap. The sealing gap is filled with a magnetic fluid body (12), and the magnetic fluid body (12) is located in the middle section of the third permanent magnet (14). When the main shaft (1) generates radial vibration, the flexible component (13) deforms to absorb vibration energy. At the same time, the end of the third permanent magnet (14) and the first permanent magnet (7) on the corresponding side generate a dynamic magnetic force of like repulsion, forming a dynamic balance to prevent the third permanent magnet (14) from getting too close to the pole tooth (11).

2. The magnetic levitation magnetohydrodynamic sealing device according to claim 1, characterized in that, The sealing gap where the magnetic fluid body (12) is located is in the weakest magnetic field region in the middle section of the third permanent magnet (14) to avoid the magnetic field of the third permanent magnet (14) interfering with the magnetic field of the second permanent magnet (9).

3. The magnetic levitation magnetohydrodynamic sealing device according to claim 2, characterized in that, The third permanent magnet (14) is made of samarium cobalt permanent magnet material.

4. The magnetic levitation magnetohydrodynamic sealing device according to claim 3, characterized in that, It also includes a bearing end cap (3), a ball bearing (4) and a sealing shell (6). The bearing end cap (3) is located at the end of the main shaft (1), and the ball bearing (4) is used to support the rotation of the main shaft (1). The sealing shell (6) is fixedly connected to the bearing end cap (3) by a hexagonal head bolt (5).

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