Magnetic fluid dynamic sealing performance testing device

Abstract

The invention discloses a magnetofluid dynamic sealing performance testing device which comprises a simulation shaft, a transmission shaft, a sealing shell and a vacuum cover, the transmission shaft is vertically arranged on a support and can be driven by a motor to rotate around the axis, and the upper end of the transmission shaft is sleeved with the simulation shaft; the outer peripheral wall of the simulation shaft is in an eccentric state relative to the transmission shaft, the sealing shell is fixedly connected to the support and surrounds the outer side of the simulation shaft, the space between the inner peripheral wall of the sealing shell and the outer peripheral wall of the simulation shaft is filled with magnetic fluid, and the lower end of the simulation shaft is connected with the transmission shaft through a sealing coupler capable of stretching and retracting in the axial direction. An actuator is arranged between the simulation shaft and the support to drive the simulation shaft to move up and down along the transmission shaft, and the vacuum cover is arranged on the support and covers the sealing shell to form a sealing monitoring cavity. According to the invention, the dynamic sealing performance test problem of a large-scale magnetofluid sealing device under the composite working conditions of high-speed rotation, radial deflection and axial floating can be solved.

Description

Technical Field

[0001] This invention relates to the field of dynamic sealing technology, and more specifically to a magnetic fluid dynamic sealing performance testing device. Background Technology

[0002] The magnetic liquid sealing device creates a strong magnetic field in the gap between the rotor and stator to confine the magnetic liquid, thereby hindering the flow of the sealing medium and achieving a seal. It features a simple structure and zero leakage, and is an important component for heavy-duty centrifuges to achieve low-pressure operation and reduce air friction loss.

[0003] To extend service life and reduce maintenance costs, the rotor of a heavy-duty centrifuge requires support from sliding bearings. Due to factors such as the dynamic changes in the stiffness of the sliding bearing oil film support and the unbalanced forces within the centrifuge, the large shaft of a heavy-duty centrifuge inevitably experiences radial runout and axial float during operation. At high speeds, both radial runout and axial float significantly affect the sealing performance and stability of the dynamic sealing device. Therefore, before installation and commissioning of the entire machine, it is necessary to evaluate and test the dynamic sealing performance of the large dynamic sealing device under specific radial runout and axial float conditions.

[0004] Due to the large size and heavy weight of the rotor, traditional rotor test platforms are unable to reproduce the support environment and load levels in actual application scenarios, and cannot accurately evaluate the sealing performance of large magnetohydrodynamic sealing devices. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetic fluid dynamic sealing performance testing device to solve the problem of dynamic sealing performance testing of large magnetic fluid sealing devices under combined working conditions of high-speed rotation, radial sway and axial floating.

[0006] This invention is achieved through the following technical solution: This invention provides a magnetic fluid dynamic sealing performance testing device, comprising a simulation shaft, a drive shaft, a sealing housing, and a vacuum chamber. The drive shaft is vertically mounted on a support and can rotate around its axis via a motor. The simulation shaft is fitted onto the upper end of the drive shaft, with its outer peripheral wall eccentric relative to the drive shaft. The sealing housing is fixedly connected to the support and surrounds the outside of the simulation shaft. Magnetic fluid is filled between the inner peripheral wall of the sealing housing and the outer peripheral wall of the simulation shaft. The lower end of the simulation shaft is connected to the drive shaft via an axially extendable sealing coupling. An actuator is provided between the simulation shaft and the support to drive the simulation shaft to move up and down along the drive shaft. The vacuum chamber is mounted on the support and covers the sealing housing to form a sealing monitoring chamber.

[0007] As a further embodiment of the present invention, the simulated shaft includes a sealing cylinder, a balancing cylinder, and a cylinder seat. The cylinder seat has a through hole at its center and is fitted onto the transmission shaft. The sealing cylinder and the balancing cylinder are fitted onto the cylinder seat from the outside to the inside. The sealing cylinder is eccentrically positioned relative to the cylinder seat, and the balancing cylinder is eccentrically positioned in the opposite direction relative to the cylinder seat.

[0008] As a further embodiment of the present invention, the actuator includes a permanent magnet ring and an excitation ring. The permanent magnet ring is disposed on the analog shaft, and the excitation ring is disposed on the support. After being energized, the excitation ring can drive the analog shaft to move up and down along the axial direction.

[0009] As a further embodiment of the present invention, the bracket includes a base, a bearing seat, and an excitation base. The bearing seat is disposed on the base and a bearing is installed inside the bearing seat for axial and radial support of the transmission shaft. The excitation base is disposed on the upper end of the bearing seat for installing an excitation ring.

[0010] As a further embodiment of the present invention, the transmission shaft includes a connecting section, a bearing section, a sealing section and a sliding section arranged sequentially from bottom to top. The connecting section is used to connect to the output end of the motor, the bearing section is used to form a rotary connection with the bracket, the sealing section is used to connect to the lower end of the sealing coupling, and the sliding section is used to fit inside the simulated shaft.

[0011] As a further aspect of the present invention, a torque sensor is also included, wherein the upper end of the torque sensor is connected to the lower end of the transmission shaft via a rigid coupling, and the lower end of the torque sensor is connected to the output shaft of the motor via a flexible coupling.

[0012] As a further aspect of the present invention, a displacement sensor is also included, which is mounted on a bracket and the measuring end of the displacement sensor points to the outer circumferential surface and end face of the simulated shaft to measure the radial displacement and axial displacement of the simulated shaft.

[0013] As a further embodiment of the present invention, the vacuum shroud is provided with a mounting hole and a vacuum extraction hole, the mounting hole being connected to a vacuum gauge, and the vacuum extraction hole being used for evacuating a vacuum.

[0014] As a further embodiment of the present invention, the sealed coupling includes a bellows coupling or a tire coupling.

[0015] As a further embodiment of the present invention, the motor is fixedly mounted on the bottom of the bracket, and the output shaft of the motor is arranged coaxially with the transmission shaft.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. When the device in this invention is working, it can achieve the effect of shaft eccentricity by driving the simulated shaft to rotate through the transmission shaft, simulating the radial yaw motion of the shaft when it is subjected to unbalanced force. At the same time, the simulated shaft can move up and down relative to the transmission shaft along the axis under the action of the actuator, simulating the axial floating during the shaft movement process. This solves the problem of dynamic sealing performance testing of large magnetohydrodynamic sealing devices under the combined conditions of high-speed rotation, radial yaw and axial floating. 2. In this invention, the drive shaft and the simulated shaft are elastically connected by a sealed coupling, and the radial constraint function is achieved by the inner hole cooperating with the shaft. Torque is transmitted under the premise of achieving a sealed and floating connection, while allowing the simulated shaft to float up and down relative to the drive shaft when rotating at high speed. 3. The simulated shaft in this invention consists of a sealed cylinder and a balanced cylinder mounted on a cylinder seat. The eccentric installation of the sealed cylinder simulates the actual radial runout, while the reverse eccentric installation of the balanced cylinder achieves dynamic balance, thereby reducing the radial load caused by unbalanced forces. 4. In this invention, the radial runout and axial float of the simulated shaft can be detected in real time by the displacement sensor, which is convenient for verifying the degree of conformity between the simulated working conditions and the actual working conditions. At the same time, the torque sensor is rigidly connected to the transmission shaft, which is convenient for accurately monitoring the resistance torque of the magnetohydrodynamic seal. The torque sensor is elastically connected to the motor, which is convenient for reducing the vibration caused by assembly eccentricity. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the magnetohydrodynamic sealing performance testing device (hidden sealing housing) of the present invention; Figure 2 This is a schematic diagram of the simulated shaft structure in this invention; Figure 3 This is a schematic diagram of the support structure in this invention; Figure 4 This is a schematic diagram of the transmission shaft structure in this invention; Figure 5 This is a schematic diagram of the vacuum shroud structure in this invention; Figure 6 This is a schematic diagram of filling the space between the simulated shaft and the sealed housing with magnetofluid in this invention.

[0018] The attached diagram shows the markings and corresponding component names: Simulation shaft 1, sealing cylinder 1-1, balancing cylinder 1-2, cylinder seat 1-3, actuator 2, permanent magnet ring 2-1, excitation ring 2-2, sealing coupling 3, bracket 4, base 4-1, bearing seat 4-2, excitation base 4-3, transmission shaft 5, connecting section 5-1, bearing section 5-2, sealing section 5-3, sliding section 5-4, rigid coupling 6, torque sensor 7, flexible coupling 8, motor 9, displacement sensor 10, vacuum hood 11, mounting hole 11a, evacuation hole 11b, vacuum gauge 12, sealing housing 13, magnetofluid 14. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0024] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0025] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0026] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0027] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0028] Please refer to Figures 1 to 6This application provides a magnetic fluid dynamic sealing performance testing device, including a simulation shaft 1, a transmission shaft 5, a sealing housing 13, and a vacuum chamber 11. The transmission shaft 5 is vertically mounted on a support 4 and can be driven by a motor 9 to rotate around its axis. The simulation shaft 1 is fitted onto the upper end of the transmission shaft 5, and the outer peripheral wall of the simulation shaft 1 is eccentric relative to the transmission shaft 5. The sealing housing 13 is fixedly connected to the support 4 and surrounds the outside of the simulation shaft 1. The space between the inner peripheral wall of the sealing housing 13 and the outer peripheral wall of the simulation shaft 1 is filled with magnetic fluid 14. The lower end of the simulation shaft 1 is connected to the transmission shaft 5 through an axially extendable sealing coupling 3. An actuator 2 is provided between the simulation shaft 1 and the support 4 to drive the simulation shaft 1 to move up and down along the transmission shaft 5. The vacuum chamber 11 is mounted on the support 4 and covers the sealing housing 13 to form a sealing monitoring chamber.

[0029] The aforementioned drive shaft 5 is rotatably mounted on the bracket 4. The simulated shaft 1 is slidably fitted onto the upper end of the drive shaft 5. The sealing housing 13 surrounds the outside of the simulated shaft 1, and the inner peripheral wall of the sealing housing 13 and the outer peripheral wall of the simulated shaft 1 are filled with magnetic fluid 14, so that a sealing interface is formed between the two. Since the outer peripheral wall of the simulated shaft 1 is eccentric relative to the drive shaft 5, the shaft eccentricity effect can be achieved when the drive shaft 5 drives the simulated shaft 1 to rotate through the sealing coupling 3, thereby simulating the radial yaw motion of the shaft when it is subjected to unbalanced force. At the same time, the simulated shaft 1 can also move up and down relative to the drive shaft 5 along the axis under the action of the actuator 2, thereby simulating the axial floating during the shaft movement. By monitoring the change in vacuum degree in the internal cavity of the vacuum chamber 11, the problem of dynamic sealing performance testing of large magnetic fluid sealing devices under combined conditions of high-speed rotation, radial yaw and axial floating is solved.

[0030] Since the simulation shaft 1 has axial sliding relative to the transmission shaft 5, there is a certain gap between the mating surfaces of the two. Therefore, the transmission shaft 5 and the simulation shaft 1 in this application are elastically connected by an axially expandable sealed coupling 3, and the radial constraint function is achieved by the inner hole cooperating with the shaft. This allows torque to be transmitted under the premise of achieving a sealed and floating connection, while also allowing the simulation shaft 1 to float up and down relative to the transmission shaft 5 when rotating at high speed.

[0031] It should be noted that in order to fill the space between the inner peripheral wall of the sealing housing 13 and the outer peripheral wall of the simulated shaft 1 to form a magnetic liquid sealing interface, a strong magnetic field needs to be created in the gap between the rotor and the stator to constrain the magnetic liquid, thereby hindering the flow of the sealing medium to achieve sealing. The relevant magnets are not shown in the figures in this application without affecting the description.

[0032] According to some embodiments of this application, the simulated shaft 1 includes a sealing cylinder 1-1, a balancing cylinder 1-2, and a cylinder seat 1-3. The cylinder seat 1-3 has a through hole in the center and is fitted onto the transmission shaft 5. The sealing cylinder 1-1 and the balancing cylinder 1-2 are fitted onto the cylinder seat 1-3 from the outside to the inside. The sealing cylinder 1-1 is eccentrically arranged relative to the cylinder seat 1-3, and the balancing cylinder 1-2 is eccentrically arranged in the opposite direction relative to the cylinder seat 1-3.

[0033] The aforementioned cylinder seat 1-3 has an axially oriented through hole at its center, which is used to form a sliding fit with the upper outer circle of the drive shaft 5. The sealing cylinder 1-1 is fitted onto the cylinder seat 1-3. The outer peripheral wall of the sealing cylinder 1-1 is opposite to the inner peripheral wall of the sealing shell 13 and has a certain gap to fill the magnetofluid 14. In this application, the eccentric installation of the sealing cylinder 1-1 simulates actual radial runout, while the reverse eccentric installation of the balancing cylinder 1-2 achieves dynamic balance, thereby reducing the radial load caused by unbalanced forces.

[0034] According to some embodiments of this application, the actuator 2 includes a permanent magnet ring 2-1 and an excitation ring 2-2. The permanent magnet ring 2-1 is disposed on the analog shaft 1, and the excitation ring 2-2 is disposed on the bracket 4. When energized, the excitation ring 2-2 can drive the analog shaft 1 to move up and down along the axial direction.

[0035] Specifically, the permanent magnet ring 2-1 is disposed on the outer peripheral wall of the disk at the lower end of the cylinder seat 1-3, and the excitation ring 2-2 is disposed on the support 4. By passing current through the excitation ring 2-2 and changing the magnitude and direction of the current, a changing electromagnetic force can be applied to the permanent magnet ring 2-1, driving the simulated shaft 1 to move up and down along the axial direction, thereby simulating the actual axial floating of the rotating shaft.

[0036] According to some embodiments of this application, the bracket 4 includes a base 4-1, a bearing seat 4-2, and an excitation base 4-3. The bearing seat 4-2 is disposed on the base 4-1, and a bearing is installed inside the bearing seat 4-2 for axial and radial support of the transmission shaft 5. The excitation base 4-3 is disposed on the upper end of the bearing seat 4-2 for installing the excitation ring 2-2.

[0037] Specifically, the aforementioned base 4-1 has a certain vertical height, the bearing seat 4-2 is fixedly installed on the top of the base 4-1, and the axial and radial support of the transmission shaft 5 is achieved through the bearing installed inside the bearing seat 4-2. The excitation base 4-3 is fixedly installed on the upper end of the bearing seat 4-2 and has an annular inner cavity, and the excitation ring 2-2 is installed on the inner peripheral wall of the excitation base 4-3.

[0038] According to some embodiments of this application, the transmission shaft 5 includes a connecting section 5-1, a bearing section 5-2, a sealing section 5-3, and a sliding section 5-4 arranged sequentially from bottom to top. The connecting section 5-1 is used to connect to the output end of the motor 9, the bearing section 5-2 is used to form a rotary connection with the bracket 4, the sealing section 5-3 is used to connect to the lower end of the sealing coupling 3, and the sliding section 5-4 is used to fit inside the simulated shaft 1.

[0039] Specifically, bearing section 5-2 forms a rotary support connection with bearing housing 4-2 through bearing, and connecting section 5-1 extends from the lower end of bearing housing 4-2 to connect with the output end of motor 9. The end face of sealing section 5-3 is connected to the lower end of sealing coupling 3, the upper end of sealing coupling 3 is connected to the lower end of cylinder seat 1-3, and simulated shaft 1 is fitted on sliding section 5-4.

[0040] According to some embodiments of this application, a torque sensor 7 is also included. The upper end of the torque sensor 7 is connected to the lower end of the transmission shaft 5 via a rigid coupling 6, and the lower end of the torque sensor 7 is connected to the output shaft of the motor 9 via a flexible coupling 8. Specifically, the rigid coupling 6 connects the upper end of the torque sensor 7 to the lower end of the connecting section 5-1 of the transmission shaft 5, and the flexible coupling 8 connects the lower end of the torque sensor 7 to the output shaft of the motor 9. This torque sensor 7 has torque measurement and rotation transmission functions. The rigid connection between the torque sensor 7 and the transmission shaft 5 facilitates accurate monitoring of the resistance torque of the magnetohydrodynamic 14 seal, while the flexible connection between the torque sensor 7 and the motor 9 helps reduce vibration caused by assembly eccentricity.

[0041] According to some embodiments of this application, a displacement sensor 10 is also included. The displacement sensor 10 is mounted on the bracket 4, and the measuring end of the displacement sensor 10 points to the outer circumferential surface and end face of the simulated shaft 1 to measure the radial and axial displacements of the simulated shaft 1. By setting the displacement sensor 10, the radial runout and axial float of the simulated shaft 1 can be detected in real time, which facilitates the verification of the degree of conformity between the simulated working conditions and the actual working conditions.

[0042] It should be noted that when arranging the displacement sensor 10, the measuring end needs to be pointed towards the outer circumferential surface and end face of the simulated shaft 1 in order to measure the radial yaw displacement and axial floating displacement of the simulated shaft 1. The mounting structure of the displacement sensor 10 is not shown in this application; those skilled in the art can design and arrange it according to the actual space.

[0043] According to some embodiments of this application, the vacuum shroud 11 is provided with a mounting hole 11a and a suction hole 11b. The mounting hole 11a is connected to a vacuum gauge 12, and the suction hole 11b is used for evacuation. The vacuum shroud 11 is a cylindrical structure with a closed upper end and an open lower end. The lower end of the vacuum shroud 11 is fixed to the upper end of the excitation base 4-3 near the outer edge, and the sealing shell 13 is fixed to the upper end of the excitation base 4-3 near the inner edge. The vacuum shroud 11 covers the sealing shell 13 and the simulation shaft 1, forming a sealed monitoring chamber inside the vacuum shroud 11.

[0044] The aforementioned mounting hole 11a and evacuation hole 11b are both located on the upper end of the vacuum chamber 11. The mounting hole 11a is used to mount the vacuum gauge 12, and the evacuation hole 11b is used to connect vacuum equipment to evacuate the inside of the vacuum chamber 11. Since the sealed monitoring chamber formed inside the vacuum chamber 11 is actually a sealed cavity, when the magnetohydrodynamic sealing performance is good, the vacuum level inside the vacuum chamber 11 will remain constant. If leakage occurs in the magnetohydrodynamic seal during the rotation of the drive shaft 5, the vacuum level inside the vacuum chamber 11 will change. Therefore, by monitoring the changes in the vacuum gauge 12, the quality of the magnetohydrodynamic dynamic sealing performance can be determined.

[0045] According to some embodiments of this application, the sealing coupling 3 includes a bellows coupling or a tire coupling. The upper end of the sealing coupling 3 is connected to the lower end of the cylindrical seat 1-3 of the simulated shaft 1, and the lower end of the sealing coupling 3 is connected to the end face of the sealing section 5-3 of the transmission shaft 5, thereby sealing the sliding gap between the simulated shaft 1 and the transmission shaft 5. The sealing coupling 3 is axially shortenable and elongable, achieving elastic connection, torque transmission, and sealing between the transmission shaft 5 and the simulated shaft 1.

[0046] According to some embodiments of this application, the motor 9 is fixedly mounted on the bottom of the bracket 4, and the output shaft of the motor 9 is coaxially arranged with the transmission shaft 5. Specifically, the motor 9 is mounted on the bottom of the base 4-1 to drive the transmission shaft 5 to rotate.

[0047] During testing, the sealing housing 13 is mounted on the bracket 4, and the magnetofluid 14 fills the gap between the sealing housing 13 and the sealing cylinder 1-1. The sealing cylinder 1-1 is adjusted to be eccentrically mounted relative to the cylinder seat 1-3, and the balancing cylinder 1-2 is adjusted to be eccentrically mounted relative to the cylinder seat 1-3 and the sealing cylinder 1-1 in the opposite direction, achieving a dynamic balance effect. When the drive shaft 5 drives the simulated shaft 1 to rotate, an eccentric shaft effect can be achieved, simulating the radial yaw motion of the shaft under unbalanced force. By powering the actuator 2 and passing current through the excitation ring 2-2 and changing the magnitude and direction of the current, a changing electromagnetic force can be applied to the permanent magnet ring 2-1, driving the simulated shaft 1 to move up and down along the axial direction of the drive shaft 5, simulating the axial floating during the shaft's movement.

[0048] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of 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 within the scope of protection of the present invention.

Claims

1. A magnetohydrodynamic sealing performance testing device, characterized in that, The device includes a simulation shaft, a drive shaft, a sealed housing, and a vacuum chamber. The drive shaft is vertically mounted on a support and can rotate around its axis via a motor. The simulation shaft is fitted onto the upper end of the drive shaft, and its outer peripheral wall is eccentric relative to the drive shaft. The sealed housing is fixedly connected to the support and surrounds the outside of the simulation shaft. The space between the inner peripheral wall of the sealed housing and the outer peripheral wall of the simulation shaft is filled with a magnetohydrodynamic fluid. The lower end of the simulation shaft is connected to the drive shaft via an axially extendable sealed coupling. An actuator is installed between the simulation shaft and the support to drive the simulation shaft to move up and down along the drive shaft. The vacuum chamber is mounted on the support and covers the sealed housing to form a sealed monitoring chamber.

2. The magnetic fluid dynamic sealing performance testing device according to claim 1, characterized in that, The simulated shaft includes a sealing cylinder, a balancing cylinder, and a cylinder seat. The cylinder seat has a through hole in the center and is fitted onto the drive shaft. The sealing cylinder and the balancing cylinder are fitted onto the cylinder seat from the outside to the inside. The sealing cylinder is eccentrically positioned relative to the cylinder seat, and the balancing cylinder is eccentrically positioned in the opposite direction relative to the cylinder seat.

3. The magnetic fluid dynamic sealing performance testing device according to claim 1, characterized in that, The actuator includes a permanent magnet ring and an excitation ring. The permanent magnet ring is mounted on the analog shaft, and the excitation ring is mounted on a support. When energized, the excitation ring can drive the analog shaft to move up and down along the axial direction.

4. The magnetic fluid dynamic sealing performance testing device according to claim 3, characterized in that, The bracket includes a base, a bearing housing, and an excitation base. The bearing housing is disposed on the base and a bearing is installed inside the bearing housing for axial and radial support of the transmission shaft. The excitation base is disposed on the upper end of the bearing housing for installing an excitation ring.

5. The magnetic fluid dynamic sealing performance testing device according to claim 1, characterized in that, The drive shaft includes a connecting section, a bearing section, a sealing section, and a sliding section arranged sequentially from bottom to top. The connecting section is used to connect to the output end of the motor, the bearing section is used to form a rotary connection with the bracket, the sealing section is used to connect to the lower end of the sealing coupling, and the sliding section is used to fit inside the simulated shaft.

6. The magnetic fluid dynamic sealing performance testing device according to claim 1, characterized in that, It also includes a torque sensor, the upper end of which is connected to the lower end of the drive shaft via a rigid coupling, and the lower end of which is connected to the output shaft of the motor via a flexible coupling.

7. The magnetic fluid dynamic sealing performance testing device according to claim 1, characterized in that, It also includes a displacement sensor, which is mounted on a bracket and the measuring end of the displacement sensor points to the outer circumferential surface and end face of the simulated shaft to measure the radial and axial displacement of the simulated shaft.

8. The magnetic fluid dynamic sealing performance testing device according to claim 1, characterized in that, The vacuum hood is provided with a mounting hole and an air extraction hole. The mounting hole is connected to a vacuum gauge, and the air extraction hole is used for evacuating a vacuum.

9. The magnetohydrodynamic sealing performance testing device according to claim 1, characterized in that, The sealed coupling includes a bellows coupling or a tire coupling.

10. The magnetohydrodynamic sealing performance testing device according to claim 1, characterized in that, The motor is fixedly mounted on the bottom of the bracket, and the output shaft of the motor is arranged coaxially with the transmission shaft.

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