Magnetorheological damper with variable-section piston structure

Abstract

The invention relates to a magnetorheological damper with a variable-section piston structure. The magnetorheological damper comprises a shell filled with magnetorheological fluid, a piston arranged in the shell, a piston rod connected with the piston and a permanent magnet arranged outside the shell in a sleeving mode. One end of the shell is provided with a through hole, one end of the piston rod penetrates through the through hole and extends into the shell to be connected with the piston, and the piston rod drives the piston to linearly move in the shell. The piston comprises a hollow shell and a telescopic rod arranged in the hollow shell, the hollow shell comprises a plurality of telescopic sections which are sequentially connected in a sliding mode, the telescopic rod telescopically controls the telescopic sections to slide relatively, the section size of the piston is adjusted, and therefore output damping force is adjusted. According to the damper, the effect of adjusting the output range can be achieved only by changing the internal structure of the damper, and the overall size does not need to be modified and reconstructed.

Description

Technical Field

[0001] The invention relates to a magnetorheological damper with a variable-section piston structure, belonging to the field of magnetorheological vibration reduction. Background Art

[0002] Magnetorheological fluid, as a new type of intelligent material, is composed of carrier fluid, ferromagnetic particles and various additives. Under the condition of an external magnetic field, it can be converted from a Newtonian fluid to a non-Newtonian fluid within milliseconds, thereby changing the yield stress of the magnetorheological fluid. Magnetorheological damper is a shock absorber that uses the characteristics of magnetorheological fluid to change the stiffness of the damper in real time according to the input current. Due to its advantages such as simple mechanical structure, wide dynamic range, fast response speed, low power consumption and large output damping force, magnetorheological dampers have been widely studied and applied in vibration control fields such as vehicle suspension, human prosthetic knee joints, and earthquake disaster reduction.

[0003] However, traditional magnetorheological dampers usually use a single excitation coil or permanent magnet to generate a magnetic field, which results in uneven magnetic field distribution, resulting in poor damping force stability; the damping force adjustment range is limited, making it difficult to meet high dynamic response requirements; magnetorheological fluid is prone to sedimentation after long-term standing, reducing performance and increasing maintenance costs. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a magnetorheological damper capable of changing the cross-sectional size of a piston to adjust the damping force.

[0005] In order to achieve the above-mentioned purpose, the technical solution proposed in the present invention is: a magnetorheological damper with a variable-section piston structure, comprising a shell filled with magnetorheological fluid, a piston arranged in the shell, a piston rod connected to the piston and a permanent magnet sleeved outside the shell; one end of the shell is provided with a through hole, one end of the piston rod passes through the through hole and extends into the shell to be connected to the piston, and the piston rod drives the piston to move linearly in the shell; the piston comprises a hollow shell and a telescopic rod arranged in the hollow shell, the hollow shell comprises a plurality of telescopic segments slidably connected in sequence, the telescopic rod telescopes to control the relative sliding of the plurality of telescopic segments, adjusts the cross-sectional size of the piston, and thereby adjusts the output damping force.

[0006] A further design of the above technical solution is as follows: a sealing cover plate is provided at the position of the shell corresponding to the through hole, a sealing filler is provided in the sealing cover plate, and one end of the piston rod passes through the sealing cover plate and then extends into the shell from the through hole to connect with the piston.

[0007] The hollow shell also includes two fixed side walls, two sliding side walls, a fixed top plate and a fixed bottom plate. The two sliding side walls are respectively slidably connected between the two fixed side walls to form a telescopic frame of the hollow shell; the two ends of the telescopic rod are fixedly connected to the two sliding side walls; the fixed top plate and the fixed bottom plate are respectively fixedly connected between the two fixed side walls, and a number of telescopic segments are symmetrically arranged on both sides of the fixed top plate to form a telescopic top plate of the hollow shell, and a number of telescopic segments are symmetrically arranged on both sides of the fixed bottom plate to form a telescopic bottom plate of the hollow shell; the two ends of the telescopic segments are respectively slidably connected to the two fixed side walls, and the piston rod is connected to the fixed top plate.

[0008] The fixed side wall is provided with a slide groove arranged along the expansion and contraction direction of the piston, and the sliding side wall and both ends of the expansion and contraction segment are provided with sliding blocks matched with the slide groove.

[0009] The top of the telescopic segment is provided with a guide groove arranged along the telescopic direction of the piston, and the bottom is provided with a guide rod matched with the guide groove. Two adjacent telescopic segments are slidably connected through the matching of the guide rod and the guide groove.

[0010] The interior of the piston is filled with sealing filler.

[0011] The sealing filler is hydrophilic polyurethane.

[0012] A displacement sensor is provided at the end of the telescopic rod.

[0013] A plurality of excitation coils are arranged outside the shell, and the excitation coils generate a magnetic field when energized to adjust the viscosity of the magnetorheological fluid, thereby adjusting the output damping force.

[0014] The magnetorheological fluid is an oil-based ferromagnetorheological fluid, the carrier fluid is a synthetic hydrocarbon, the volume percentage of the magnetic powder is 40%, the weight percentage of the magnetic powder is 86%, and the density is 3.65g / cm 3 .

[0015] The beneficial effects of the present invention are: The damper of the present invention can adjust the cross-sectional size of the piston through the telescopic rod, thereby adjusting the damping force output by the damper. The effect of adjusting the output range can be achieved by simply changing the internal structure of the damper, without modifying and reconstructing the overall size.

[0016] The present invention sets a number of excitation coils through the response of magnetorheological fluid to the magnetic field, which can form a multi-level magnetic field adjustment scheme, which can significantly improve the utilization rate of the magnetic field and enhance the adjustment accuracy of the damping force. For specific output damping force requirements, it can be controlled by controlling the magnetic field as a means to cooperate with the variable cross-section piston damper for controllable adjustment, realize the active and controllable magnetorheological vibration reduction, and expand the adjustment range of the output damping force.

[0017] The present invention is provided with a permanent magnet, which can effectively solve the problem of performance degradation caused by sedimentation of magnetorheological fluid in a magnetorheological damper that has been left for a long time, and always maintain the damper at a high working level. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the first embodiment of the invention; Figure 2 for Figure 1 Schematic diagram of the structure of the middle piston; Figure 3 for Figure 2 Schematic diagram of connection between adjacent telescopic segments; Figure 4 This is a schematic diagram of the structure of the second embodiment of the invention; Figure 5 This is the excitation coil control circuit diagram; Figure 6 is the damping force curve corresponding to different piston cross-sectional sizes; Figure 7 is the damping force curve corresponding to different magnetic fields; 1-sealing packing, 2-piston rod, 3-sealing cover plate, 4-housing, 41-patch sensor, 5-piston, 51-fixed side plate, 52-sliding side plate, 53-fixed top plate, 54-fixed bottom plate, 55-telescopic segment, 551-guide groove, 552-guide rod, 56-telescopic rod, 57-control unit, 58-external control system, 6-permanent magnet, 7-magnetorheological fluid, 8-excitation coil. DETAILED DESCRIPTION

[0019] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Embodiment 1

[0020] like Figure 1 As shown, the magnetorheological damper of the variable cross-section piston structure of the present embodiment includes a shell 4, the interior of the shell 4 is filled with a magnetorheological fluid 7, a piston 5 is arranged in the shell, and the piston 5 is connected to the piston rod 2. The upper end of the piston rod 2 is designed with an opening to facilitate the connection of the drive device to drive the telescopic rod 2, and the lower end is designed with a threaded design. The corresponding part of the piston 5 is provided with a threaded hole connected to the lower end of the plug rod 2, which is convenient for replacement and cleaning. The outer shell is covered with a permanent magnet 6, which can generate a magnetic field without an external energy supply and is responsible for providing a stable background magnetic field. In order to avoid the influence of the external magnetic field on the piston, the piston 5 and the piston rod 2 are both made of non-magnetic rigid material.

[0021] In this embodiment, a through hole is provided at one end of the housing 4, and a sealing cover plate 3 is provided at the housing 4 corresponding to the through hole. One end of the piston rod 2 passes through the sealing cover plate 3 and then extends into the housing 4 from the through hole to connect with the piston 5. The piston rod 2 drives the piston 3 to perform linear motion in the housing 4. The piston comprises a hollow shell and a telescopic rod arranged in the hollow shell, the hollow shell comprises a plurality of telescopic segments slidably connected in sequence, the telescopic rod telescopes to control the relative sliding of the plurality of telescopic segments, adjusts the cross-sectional size of the piston, and thus adjusts the output damping force.

[0022] Combination Figure 2 As shown, the piston 2 includes a hollow shell and a telescopic rod 56 arranged in the hollow shell, the hollow shell includes two fixed side walls 51, two sliding side walls 52, a fixed top plate 53, a fixed bottom plate 54 and a plurality of telescopic segments 55, the two sliding side walls 52 are respectively slidably connected between the two fixed side walls 51 to form a telescopic quadrilateral frame of the hollow shell; the two ends of the telescopic rod 56 are fixedly connected to the two sliding side walls 52; the fixed top plate 53 and the fixed bottom plate 54 are respectively fixedly connected between the two fixed side walls 51, and the fixed top plate 53 is symmetrically provided with a plurality of slidably connected segments 55 in sequence. The telescopic segments 55 of the part, the two ends of the overall structure formed by the several telescopic segments of the part are respectively connected to the corresponding sides of the fixed top plate 53 and the corresponding sliding side walls 52, forming a telescopic top plate of the hollow shell; similarly, the fixed bottom plate 54 is symmetrically provided with a plurality of telescopic segments 55 that are slidably connected in sequence on both sides, and the two ends of the overall structure formed by the several telescopic segments of the part are respectively connected to the corresponding sides of the fixed bottom plate 54 and the corresponding sliding side walls 52 to form a telescopic bottom plate of the hollow shell; the two ends of the telescopic segments are respectively slidably connected to the two fixed side walls, and the piston rod 2 is connected to the fixed top plate. In this embodiment, a slide groove is provided on the fixed side wall 51 along the direction of piston expansion and contraction, and sliders that cooperate with the slide groove are provided at both ends of the sliding side wall 52 and the telescopic segments 55, so as to facilitate the sliding of the sliding side wall 52 and the telescopic segments 55 relative to the fixed side wall 51, thereby realizing the variable cross-section of the piston. In this embodiment, since the sliding side wall 52 and the telescopic segment 55 are arranged in an axially overlapping manner, the fixed side wall 51 is provided with a sliding groove corresponding to the sliding side wall 52 and each telescopic segment 55 in the axial direction to limit the telescopic range of each telescopic segment 55. Figure 3 As shown, the top of the telescopic segment 55 is provided with a guide groove 551 arranged along the expansion and contraction direction of the piston, and the bottom is provided with a guide rod 552 matched with the guide groove. Two adjacent telescopic segments are stacked up and down, and are slidably connected by the cooperation of the guide rod and the guide groove to achieve relative sliding of adjacent telescopic segments 55. In this embodiment, the sliding side wall 52 and the telescopic segment 55 are both rectangular or arc-shaped sheet structures, and can be stacked on each other during the sliding process.

[0023] The telescopic rod 56 is an electric telescopic rod, and a control unit 57 is provided inside the telescopic rod for controlling the extension and retraction of the telescopic rod 56. An external control system 58 is provided outside the magnetorheological damper and is communicated with the control unit for sending control instructions to the control unit. The control unit controls the extension and retraction of the telescopic rod, pushes / pull the telescopic segment and the sliding side wall to move, and realizes the cross-sectional adjustment of the piston.

[0024] Displacement sensors are also provided at both ends of the telescopic rod to monitor the dimensional changes of the piston cross section.

[0025] The piston 5 is filled with sealing filler inside, adopting a sealing structure; or is not filled with sealing filler, adopting a non-sealing structure. Embodiment 2

[0026] The further design of this embodiment is that the interior of the piston 5 and the interior of the sealing cover plate 3 are filled with sealing fillers. The sealing filler 1 is a hydrophilic polyurethane. While achieving sealing, it can be deformed as the inner cavity shrinks / expands during the piston adjustment process to always fill the interior of the piston, achieving relative sealing. Even if a small amount of magnetorheological fluid enters the piston, it does not affect the performance, or the magnetorheological fluid can be replenished by replenishing the fluid. The threaded hole of the piston 5 is set on the fixed top plate 53 and is connected to the hollow structure inside the piston for adding sealing fillers.

[0027] In this embodiment, the magnetorheological fluid 7 is an oil-based ferromagnetorheological fluid, the carrier fluid is a synthetic hydrocarbon, the volume percentage of the magnetic powder is 40%, the weight percentage of the magnetic powder is 86%, and the density is 3.65 g / cm 3 .

[0028] When assembling the magnetorheological damper of this embodiment, first, tighten the piston rod 2 and the piston 5 through the thread to ensure that they are tightly combined into a whole so that they can be stably displaced during use. When assembling the sealing cover plate, evenly fill the appropriate amount of sealing filler between the cover plates to ensure that the filler completely fills the internal cavity of the sealing cover plate to provide a good sealing effect and prevent liquid leakage or air from entering. The sealing cover plate 3 and the upper cover plate of the shell 4 are firmly bonded together to ensure that the sealing cover plate can form a stable closed structure with the upper cover plate of the shell to avoid loosening due to vibration or external force. The assembled piston rod 2 is passed through the reserved openings of the sealing cover plate 3 and the upper cover plate of the shell 4 to connect these components into a whole to ensure that all components can work smoothly together. Inject magnetorheological fluid into the shell, and the liquid level should reach 60% of the height of the shell. Then, slowly immerse the piston 5 in the magnetorheological fluid in the shell until the piston is completely immersed in the liquid. Use a syringe to inject magnetorheological fluid again at the upper end of the shell until the remaining space in the shell is filled to ensure that there is no gap in the liquid. The upper cover of the housing 4 is firmly bonded to the rest of the housing to ensure the sealing and stability between the upper cover and the housing. The assembled device is left to stand for a period of time until the bonding is firm to avoid loosening or leakage during use. Finally, a ring-shaped permanent magnet is placed at the lower edge of the housing to generate a constant magnetic field to provide a suitable magnetic field environment for the magnetorheological fluid.

[0029] The initial state of piston 5 is in the maximum expansion state (maximum cross section), and all segments are in the outward position. At this time, the effective force area of ​​the piston is the largest, and the damping effect on the fluid is the strongest. It is suitable for low-speed and high-damping conditions (such as buffer braking and low-speed stability control). According to the actual situation, the external control system sends instructions for remote control. After receiving the instructions, the telescopic rod gradually shrinks some segments to reduce the effective force area of ​​the piston. Due to the movement of the segments, the size of the fluid channel changes, affecting the fluid flow resistance and realizing dynamic damping adjustment. When all variable segments are fully retracted, the piston cross section is reduced, the piston is in the minimum cross-section state, and the damping effect is reduced. At this time, it is suitable for high-speed and low-damping conditions (such as high-frequency vibration absorption and rapid response adjustment). Embodiment 3

[0030] This embodiment is further designed on the basis of the first embodiment, specifically, a plurality of excitation coils 8 are provided outside the housing 4, such as Figure 4As shown, the excitation coil 8 is energized to generate a magnetic field, which adjusts the viscosity of the magnetorheological fluid, thereby adjusting the output damping force. The damping forces are divided into two groups, and the excitation coils of each group are distributed along the axial direction of the damper. In this embodiment, four excitation coils are provided, which are marked as L1, L2, L3, and L4 respectively. Each coil can independently control the current size and direction, thereby adjusting the local magnetic field strength. The permanent magnet marked as M can provide a uniform and stable magnetic field, and is arranged alternately with the excitation coil to form a composite magnetic field source. The permanent magnet provides a stable background magnetic field, which can always keep the magnetorheological fluid in the damper in an activated state to prevent sedimentation from affecting the performance of the magnetorheological fluid.

[0031] like Figure 5 As shown, the damper of this embodiment implements multi-level magnetic field regulation specifically as follows: the system is connected to a 24V power supply. When the circuit control main switch F1 is disconnected, the excitation coils L1, L2, L3, and L4 have no magnetic field generated, and the overall magnetic field of the device is emitted by the permanent magnet M. At this time, the magnetic field generated by the permanent magnet M can be used under low magnetic field conditions, and can also maintain the magnetorheological fluid in an activated state to prevent the magnetorheological fluid from being deposited for a long time and affecting the performance of the damper. When the damping force demand increases, turn on the control switches F1 and S2, so that the excitation coils L3 and L4 are energized and generate an induced magnetic field, increase the magnetic field strength around the damper, and increase the output damping force. When the damping force demand further increases, turn off the control switch S2 and turn on the control switch S1. Because the excitation coils L3 and L4 are far away from the magnetorheological fluid, and the excitation coils L1 and L2 are close to the magnetorheological fluid, L1 and L2 can provide a greater magnetic field strength, which can provide a greater damping force than turning on L3 and L4. When the damping force demand is greater, the control switches F1, S1, and S2 are turned on at the same time, so that the excitation coils L1, L2, L3, and L4 are all in working state. At this time, the maximum induced magnetic field can be provided for the damper as a whole, thereby maximizing the output damping force.

[0032] The multi-stage magnetic field regulating device composed of multiple excitation coils and permanent magnets in this embodiment can realize the gradient distribution of the magnetic field, and can mainly perform 5-stage step adjustment. The first-stage control switch F1 is closed and the permanent magnet is removed. At this time, the entire device is in a non-magnetic field state, and the magnetorheological fluid is not affected by the magnetic field and maintains liquid properties; the second-stage control switch F1 is closed and the permanent magnet M is added. At this time, only the permanent magnet outputs the magnetic field in the device, and the magnetorheological fluid also changes from a liquid state to a quasi-solid state with the emission of the magnetic field, and has a certain damping effect. At this time, the uniform and stable magnetic field emitted by the permanent magnet can also maintain the state of the magnetorheological fluid, so that it is in an activated state for a long time, preventing the magnetorheological fluid from settling for a long time and affecting the damper performance; the third-stage control switches F1 and S2 are opened, and the control The control switch S1 is closed. At this time, the two excitation coils L3 and L4 far from the magnetorheological fluid start to work under the influence of the input current to provide a magnetic field, strengthen the magnetic field strength in the second step, and improve the performance of the damper; the fourth-level control switches F1 and S1 are opened, and the control switch S2 is closed. At this time, the two excitation coils L1 and L2 close to the magnetorheological fluid start to work under the influence of the input current to provide a magnetic field. Because the closer the magnetorheological fluid is, the more magnetic flux lines can pass through the magnetorheological fluid, and the induced magnetic field output by the overall device is larger than that of the third-level device; the fifth-level control switches F1, S1, and S2 are all turned on. At this time, the permanent magnet M, the excitation coils L1, L2, L3, and L4 start to work at the same time, and the magnetic field value generated by the device is the largest. Through multi-level magnetic field regulation, the utilization rate of the magnetic field can be significantly improved, the adjustment accuracy of the damping force can be enhanced, and the adjustment range of the damping force can be further expanded.

[0033] In this embodiment, a patch sensing device is provided on the inner side of the shell 4, which is composed of a patch sensor 41 and a pressure display module. The two are connected via Bluetooth. The patch sensor 41 adopts a thin film pressure sensor, and the pressure display module is equipped with a high-definition display screen, which can display the measured pressure value in real time and intuitively, facilitating user monitoring.

[0034] Magnetorheological dampers with different cross-sectional piston sizes are tested to collect damping force, cross-sectional dimensions and magnetic field data. The output damping force of each structure under different magnetic field strengths is determined, and the mathematical relationship function of damping force-piston structure-magnetic field is fitted, and rapid query and calculation are achieved through the processing terminal. When it is necessary to maintain the damper output at a specific damping force, the required damping force can be input into the processing terminal. The terminal matches the required magnetic field strength according to the setting, and sends instructions to the electromagnet device so that the system dynamically adjusts the magnetic field strength to maintain a constant output damping force. When in a specific magnetic field strength, the required constant magnetic field value can be input into the processing terminal. The terminal analyzes and displays the damping force that can be output by each piston cross section under the magnetic field based on the data in the collection library, and the user can select according to needs.

[0035] Comparative Example The comparative sample adopts the spacing between the two sliding side walls of the pistonD Five variable cross-section pistons of 8 mm, 12 mm, 16 mm, 20 mm and 24 mm, each with a piston length of 10 mm, were obtained using the preparation process of Example 1. The compression rate was 5 mm / min, and the stretching rate was 5 mm / min. The comparative effect was: 1. Variable cross-section size D piston Compression under an external magnetic field can reflect the output damping force of the magnetorheological damper. The present invention compares five types of piston magnetorheological dampers with variable cross-sectional sizes under an applied magnetic field. After multiple tests with the magnetic field size controlled at 0.5T, the following results are obtained: Figure 6 As shown in the figure, the output damping capacity is from large to small piston diameter D=24 mm, D=20 mm, D=16 mm, D=12 mm, and D=8 mm, that is, the larger the piston cross-sectional size D, the greater the output damping force. The variable cross-sectional piston design proposed in this embodiment can effectively control the cross-sectional change of the piston and adjust the output force of the system within a certain range.

[0036] 2. Output damping force under multi-level magnetic field regulation Different magnetic field intensities are set by multi-stage magnetic field adjustment. The first stage magnetic field intensity is 0 T, the second stage magnetic field intensity is 0.5 T, the third stage magnetic field intensity is 0.6 T, the fourth stage magnetic field intensity is 0.7 T, and the fifth stage magnetic field intensity is 0.8 T. Taking the variable cross-section piston magnetorheological damper with ds=24, D=24, and h of 10 and 12 mm as an example, the output damping force of the sample under multi-stage magnetic field adjustment changes with the step as shown in the figure. Figure 7 As shown, as the number of multi-stage magnetic field adjustment levels increases, the output damping force also increases. It can be seen from this that the multi-stage magnetic field adjustment device provided by the present invention can indeed achieve an increase in the output damping force by adjusting the number of levels.

[0037] The technical solutions of the present invention are not limited to the above-mentioned embodiments, and any technical solutions obtained by equivalent replacement methods fall within the scope of protection required by the present invention.

Claims

1. A magnetorheological damper with a variable cross-section piston structure, characterized in that: It comprises a shell filled with magnetorheological fluid, a piston arranged in the shell, a piston rod connected to the piston and a permanent magnet sleeved outside the shell; A through hole is provided at one end of the shell, and one end of the piston rod extends through the through hole into the shell to connect with the piston, and the piston rod drives the piston to perform linear motion in the shell; The piston comprises a hollow shell and a telescopic rod arranged in the hollow shell, the hollow shell comprises a plurality of telescopic segments slidably connected in sequence, the telescopic rod telescopes to control the relative sliding of the plurality of telescopic segments, adjusts the cross-sectional size of the piston, and thus adjusts the output damping force.

2. The magnetorheological damper with a variable cross-section piston structure according to claim 1, characterized in that: The shell is provided with a sealing cover plate corresponding to the through hole, and a sealing filler is arranged in the sealing cover plate. One end of the piston rod passes through the sealing cover plate and then extends into the shell from the through hole to be connected with the piston.

3. The magnetorheological damper with a variable cross-section piston structure according to claim 2, characterized in that: The hollow shell further comprises two fixed side walls, two sliding side walls, a fixed top plate and a fixed bottom plate, the two sliding side walls are respectively slidably connected between the two fixed side walls to form a telescopic frame of the hollow shell; the two ends of the telescopic rod are fixedly connected to the two sliding side walls; The fixed top plate and the fixed bottom plate are respectively fixedly connected between the two fixed side walls, and a plurality of telescopic segments are symmetrically arranged on both sides of the fixed top plate to form a telescopic top plate of the hollow shell, and a plurality of telescopic segments are symmetrically arranged on both sides of the fixed bottom plate to form a telescopic bottom plate of the hollow shell; the two ends of the telescopic segments are respectively slidably connected to the two fixed side walls, and the piston rod is connected to the fixed top plate.

4. The magnetorheological damper with a variable cross-section piston structure according to claim 3, characterized in that: The fixed side wall is provided with a slide groove arranged along the expansion and contraction direction of the piston, and the sliding side wall and both ends of the expansion and contraction segment are provided with sliding blocks matched with the slide groove.

5. The magnetorheological damper with a variable cross-section piston structure according to claim 4, characterized in that: The top of the telescopic segment is provided with a guide groove arranged along the telescopic direction of the piston, and the bottom is provided with a guide rod matched with the guide groove. Two adjacent telescopic segments are slidably connected through the cooperation of the guide rod and the guide groove.

6. The magnetorheological damper with a variable cross-section piston structure according to any one of claims 1 to 5, characterized in that: The interior of the piston is filled with sealing filler.

7. The magnetorheological damper with a variable cross-section piston structure according to claim 6, characterized in that: The sealing filler is hydrophilic polyurethane.

8. The magnetorheological damper with a variable cross-section piston structure according to claim 7, characterized in that: A displacement sensor is provided at the end of the telescopic rod.

9. The magnetorheological damper with a variable cross-section piston structure according to claim 8, characterized in that: A plurality of excitation coils are arranged outside the shell. The excitation coils generate a magnetic field when energized to adjust the viscosity of the magnetorheological fluid, thereby adjusting the output damping force.

10. The magnetorheological damper with a variable cross-section piston structure according to claim 9, characterized in that: The magnetorheological fluid is an oil-based ferromagnetorheological fluid, the carrier fluid is a synthetic hydrocarbon, the volume percentage of the magnetic powder is 40%, the weight percentage of the magnetic powder is 86%, and the density is 3.65g / cm 3 .

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