Magnetorheological damping element based on winding type magnetic circuit built-in piston

Abstract

The magnetorheological damping element based on the winding type magnetic circuit built-in piston comprises a hydraulic cylinder and a magnetorheological damper, the hydraulic cylinder comprises a hydraulic cylinder end cover, a hydraulic cylinder barrel, a double-outlet-rod hydraulic piston and a shared end cover, and the magnetorheological damper comprises a damper outer cylinder barrel, the built-in piston, a wire rod and a damper end cover; the hydraulic cylinder and the magnetorheological damper are connected together through the common hydraulic piston and the common end cover; the magnetic isolation disc is installed between the front magnetic conduction block and the rear magnetic conduction block and is jointly arranged in the magnetic conduction cylinder to form a flow channel baffle, and the interior of the built-in piston forms a magnetorheological fluid flow channel through center flow holes of the front end cover and the rear end cover, gaps between the front end cover and the flow channel baffle, gaps between the rear end cover and the flow channel baffle and gaps between the magnetic conduction cylinder and the flow channel baffle. A winding type magnetic circuit is formed by arranging the magnetism isolating part. The structure effectively utilizes a magnetic field through a guide magnetic circuit, can improve the utilization rate of the magnetic field, can provide damping force matched with the hydraulic cylinder, and is compact in structure and small in size.

Description

Technical Field

[0001] The invention relates to the technical field of magnetorheological dampers, and in particular to a magnetorheological damping element based on a meandering magnetic circuit with a built-in piston. Background Art

[0002] Hydraulic legged robots will produce large impacts and vibrations when their feet interact with the ground. This is caused by the inherent underdamping characteristics of the hydraulic system, which makes the hydraulic equipment low in precision and poor in controllability. To address this phenomenon, active control and passive control are currently used to reduce vibrations in the device. Passive compliance control usually involves adding flexible elements such as flexible springs to the legs or joints. However, passive control can easily cause resonance in the system, which in turn affects the control accuracy of the next dynamic cycle. Active control can control force and displacement in real time, eliminating the complex structure of passive compliance control and achieving good vibration reduction effects. However, it has high performance requirements for the controller and actuator, and the control program is complex.

[0003] Magnetorheological fluid is a new type of intelligent material used in semi-active vibration reduction control. It is a mixture of base fluid, soft magnetic particles and additives. Under the action of an external magnetic field, it can change its own characteristics and produce a magnetorheological effect. It has the advantages of good controllability, reversibility and fast response. Magnetorheological damper is a device that can achieve vibration reduction control developed based on the characteristics of magnetorheological fluid. It adjusts the output damping force in real time according to the input current. It has the advantages of fast response speed, controllable and reversible, low energy consumption, etc. It has been widely used in vehicle suspension, house bridges and aerospace. Most common magnetorheological dampers are simple direct-acting shear valve structures. The coil is wound around the piston. The magnetic field generated by the coil is energized and passes vertically through the flow channel gap between the piston and the outer cylinder wall, thereby producing a magnetorheological effect. However, this type of magnetorheological damper has less magnetorheological fluid that can act, the magnetic field utilization rate is not high, and it cannot produce a wide dynamic adjustment range of damping force. At the same time, the overall volume of the magnetorheological damper is large and the space cannot be well utilized. Summary of the invention

[0004] The object of the present invention is to provide a magnetorheological damping element based on a meandering magnetic circuit with a built-in piston. The structure can improve the utilization rate of the magnetic field and provide a damping force matching the hydraulic cylinder, and has a compact structure and a small size.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a magnetorheological damping element based on a meandering magnetic circuit with a built-in piston, comprising a hydraulic cylinder and a magnetorheological damper, wherein the hydraulic cylinder comprises a hydraulic cylinder end cover, a hydraulic cylinder barrel, a double-rod hydraulic piston and a common end cover, and the magnetorheological damper comprises a damper outer cylinder barrel, a built-in piston, a wire rod and a damper end cover; the hydraulic cylinder end cover is installed at the front end of the hydraulic cylinder barrel, the damper end cover is installed at the rear end of the damper outer cylinder barrel, and the rear end of the hydraulic cylinder barrel is connected to the damper The front ends of the damper outer cylinders are connected together through a common end cover, the built-in piston is arranged in the damper outer cylinder, the double-rod hydraulic piston is arranged in the hydraulic cylinder, and the front rod of the double-rod hydraulic piston passes forward from the through hole on the hydraulic cylinder end cover, the rear rod passes backward from the through hole on the common end cover and is connected to the front of the built-in piston, the front end of the wire rod is connected to the rear of the built-in piston and passes backward from the through hole on the damper end cover; the hydraulic cylinder is filled with hydraulic oil, and the outer cylinder of the damper is filled with magnetorheological fluid; The built-in piston includes a sleeve, an excitation coil, a magnetic block, a magnetic isolation disk, a magnetic cylinder, a magnetic isolation ring and front and rear end covers, the front and rear end covers are respectively installed at the front and rear ends of the sleeve, the magnetic isolation disk is installed without a gap between the front and rear magnetic blocks, and are jointly arranged in the magnetic cylinder to form a flow channel baffle, the magnetic cylinder is arranged in the sleeve, the excitation coil is wound on the outer circumference of the magnetic cylinder, the front and rear ends of the magnetic cylinder are respectively embedded with magnetic isolation rings and fixed between the front and rear end covers, the front and rear center flow holes are respectively opened in the middle of the front and rear end covers, the front and rear end covers have gaps respectively between them and the flow channel baffle to form front and rear disc-shaped flow channels, the magnetic cylinder and the flow channel baffle have an annular gap and are connected to the front and rear disc-shaped flow channels at the same time, the rear rod of the double-rod hydraulic piston passes through the front center flow hole and is fixedly connected to the middle of the flow channel baffle.

[0006] Furthermore, the hydraulic cylinder end cover and the common end cover are respectively provided with oil inlet and outlet ports communicating with the inner cavity of the hydraulic cylinder barrel.

[0007] Furthermore, the front and rear end covers are fixedly connected to the sleeve by bolts to form an externally closed whole of the built-in piston.

[0008] Furthermore, the cross-section of the annular portion of the magnetic conductive cylinder is "T"-shaped, and the cross-section of the magnetic isolation ring is "L"-shaped. The two magnetic isolation rings are respectively nested and installed on the front and rear ends of the magnetic conductive cylinder to jointly form a coil frame for winding the excitation coil; the inner end surfaces of the front and rear end covers are provided with stepped portions, and the magnetic conductive cylinder is sealed and fixed to the stepped portions on the inner end surfaces of the front and rear end covers through the magnetic isolation rings at the front and rear ends.

[0009] Furthermore, a plurality of first protrusions are provided on the outer circumferential wall of the magnetic separator, and a plurality of first grooves are correspondingly provided on the inner circumferential wall of the magnetic conductive cylinder, so that the magnetic separator and the magnetic conductive cylinder can be relatively fixed by the cooperation of the first protrusions and the first grooves.

[0010] Furthermore, a plurality of second protrusions are provided on the front end surface of the front magnetic conductive block, and a plurality of second grooves are correspondingly provided on the rear end surface of the front end cover, so that the front magnetic conductive block and the front end cover can be relatively fixed by the cooperation between the second protrusions and the second grooves; a plurality of third protrusions are provided on the rear end surface of the rear magnetic conductive block, and a plurality of third grooves are correspondingly provided on the front end surface of the rear end cover, so that the rear magnetic conductive block and the rear end cover can be relatively fixed by the cooperation between the third protrusions and the third grooves.

[0011] Furthermore, a threaded hole is opened in the middle of the magnetic block, and the rear rod of the double-rod hydraulic piston has an external thread that cooperates with the threaded hole. The rear rod extends into the threaded hole and cooperates with it to achieve a fixed connection between the rear rod of the double-rod hydraulic piston and the flow channel baffle.

[0012] Furthermore, a dynamic seal is formed between the double-rod hydraulic piston and the hydraulic cylinder; and a dynamic seal is formed between the built-in piston and the damper outer cylinder.

[0013] Furthermore, the sleeve, the magnetic conductive block, the magnetic conductive cylinder, and the front and rear end covers are made of DT4 electrical pure iron with high magnetic permeability; the magnetic isolation disk and the magnetic isolation ring are made of 6061 aluminum alloy with low magnetic permeability.

[0014] Furthermore, the rear end cover is provided with a rear end cover through hole connecting the excitation coil and the outside of the built-in piston, the wire rod has an internal through hole, the front end of the wire rod is installed in the rear end cover through hole, and the excitation coil passes through the internal through hole of the wire rod to be connected to an external power supply; the damper end cover is provided with a magnetorheological fluid injection hole.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a magnetorheological damping element based on a meandering magnetic circuit with a built-in piston. The structure places the flow channel in the built-in piston of the magnetorheological damper, and arranges a magnetic conductive cylinder and a magnetic isolation ring to guide the magnetic circuit to pass through the flow channel multiple times, thereby greatly improving the utilization rate of the magnetic field. The overall structure is more compact. The damper is connected in series with the hydraulic cylinder to form an integrated damping element, which provides a damping force matching the hydraulic cylinder, improves the under-damped characteristics of the hydraulic valve-controlled cylinder, and is suitable for the driving joints of a hydraulic footed robot, and can effectively reduce the impact and vibration of the foot end. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of a magnetorheological vibration damping element based on a meandering magnetic circuit with a built-in piston according to an embodiment of the present invention; Figure 2 Schematic diagram of the built-in piston structure and magnetic circuit direction in an embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of the magnetic conductive cylinder in an embodiment of the present invention; Figure 4 is a schematic structural diagram of a magnetic isolation ring in an embodiment of the present invention; Figure 5 is a schematic structural diagram of a magnetic disk spacer according to an embodiment of the present invention; Figure 6 It is a schematic diagram of the structure of the magnetic conductive block in an embodiment of the present invention.

[0017] In the figure: 1-hydraulic cylinder end cover; 2-hydraulic cylinder barrel; 3-double-rod hydraulic piston; 4-common end cover; 5-damper outer cylinder barrel; 6-built-in piston; 7-conducting rod; 8-damper end cover; 9-front end cover; 10-sleeve; 11-excitation coil; 12-rear end cover; 13-magnetic block; 14-magnetic isolation disk; 15-magnetic cylinder; 16-magnetic isolation ring. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] like Figure 1-6As shown, this embodiment provides a magnetorheological damping element based on a meandering magnetic circuit built-in piston, including a hydraulic cylinder and a magnetorheological damper, wherein the hydraulic cylinder includes a hydraulic cylinder end cover 1, a hydraulic cylinder barrel 2, a double-rod hydraulic piston 3 and a common end cover 4, and the magnetorheological damper includes a damper outer cylinder barrel 5, a built-in piston 6, a wire rod 7 and a damper end cover 8. The hydraulic cylinder end cover 1 is installed at the front end of the hydraulic cylinder barrel 2, the damper end cover 8 is installed at the rear end of the damper outer cylinder barrel 5, the rear end of the hydraulic cylinder barrel 2 and the front end of the damper outer cylinder barrel 5 are connected together through the common end cover 4, the built-in piston 6 is arranged in the damper outer cylinder barrel 5, the double-rod hydraulic piston 3 is arranged in the hydraulic cylinder barrel 2, and the front side rod of the double-rod hydraulic piston 3 passes forward from the through hole on the hydraulic cylinder end cover 1, the rear side rod passes backward from the through hole on the common end cover 4 and is connected to the front of the built-in piston 6, and the front end of the wire rod 7 is connected to the rear of the built-in piston 6 and passes backward from the through hole on the damper end cover 8. The hydraulic cylinder 2 is filled with hydraulic oil to realize the reciprocating motion of the hydraulic piston. The hydraulic cylinder end cover 1 and the common end cover 4 are respectively provided with oil inlet and outlet ports connected to the left and right sides of the inner cavity of the hydraulic cylinder. The damper outer cylinder 5 is filled with magnetorheological fluid.

[0022] The built-in piston 6 includes a sleeve 10, an excitation coil 11, a magnetic block 13, a magnetic isolation disk 14, a magnetic cylinder 15, a magnetic isolation ring 16, a front end cover 9, and a rear end cover 12. The front end cover 9 and the rear end cover 12 are respectively installed at the front and rear ends of the sleeve 10. The magnetic isolation disk 14 is installed without a gap between the front and rear magnetic blocks 13, and is jointly arranged in the magnetic cylinder 15 to form a flow channel baffle. The magnetic cylinder 15 is arranged in the sleeve 10, and the excitation coil 11 is wound on the outer circumference of the magnetic cylinder 15. The front and rear ends of the magnetic cylinder 15 are respectively embedded with magnetic isolation rings 16 and fixed between the front end cover 9 and the rear end cover 12. Front and rear center flow holes are respectively opened in the middle of the front end cover 9 and the rear end cover 12. There are gaps between the front end cover 9, the rear end cover 12 and the flow channel baffle to form front and rear disc-shaped flow channels. There is an annular gap between the magnetic cylinder 15 and the flow channel baffle to form a circular flow channel and simultaneously connect the front and rear disc-shaped flow channels. When the built-in piston 6 moves forward, the magnetorheological fluid flows into the front disc-shaped flow channel from the central flow hole in the middle of the front cover 9 under the pressure of the built-in piston, flows into the rear disc-shaped flow channel through the annular flow channel, and finally flows out from the central flow hole in the middle of the rear cover 12. When the built-in piston 6 moves in the reverse direction, the flow order of the magnetorheological fluid is reversed. The rear side rod of the double-rod hydraulic piston 3 passes through the front central flow hole and is fixedly connected to the middle of the flow channel baffle.

[0023] The rear end cover 12 is provided with a rear end cover through hole connecting the excitation coil 11 and the outside of the built-in piston 6, the conductor rod 7 has an internal through hole, the front end of the conductor rod 7 is installed in the rear end cover through hole, and the excitation coil 11 passes through the internal through hole of the conductor rod 7 to connect with the external power supply. The damper end cover 8 is provided with a magnetorheological fluid injection hole.

[0024] In this embodiment, the front end cover 9 and the rear end cover 12 are fixedly connected to the sleeve 10 by bolts to form an externally closed whole of the built-in piston.

[0025] like Figure 3 As shown, the cross section of the annular portion of the magnetic tube 15 is in a "T" shape. Figure 4 As shown, the cross section of the magnetic isolation ring 16 is "L" shaped. The two magnetic isolation rings 16 are respectively nested and installed at the front and rear ends of the magnetic conductive cylinder 15, and together form a coil frame, and the excitation coil 11 is wound on the outer peripheral side of the coil frame. When the excitation coil 11 is energized, a magnetic field is generated. Due to the arrangement of the magnetic isolation disk, the magnetic isolation ring and the magnetic conductive cylinder, the magnetic circuit is guided to pass through the magnetorheological fluid channel many times, which greatly improves the utilization rate of the magnetic field and the power density ratio. The inner end faces of the front cover 9 and the rear cover 12 are both provided with stepped portions, and the magnetic conductive cylinder 15 is sealed and fixed to the stepped portions on the inner end faces of the front and rear covers through the magnetic isolation rings 16 at the front and rear ends.

[0026] In this embodiment, four small arc-shaped protrusions are provided on the outer circumferential wall of the magnetic separator 14, and four small arc-shaped grooves are correspondingly provided on the inner circumferential wall of the magnetic tube 15, so that the magnetic separator and the magnetic tube can be relatively fixed by the cooperation of the small arc-shaped protrusions and the small arc-shaped grooves. Three small circular protrusions are provided on the front end surface of the front magnetic conductive block 13, and three small circular grooves are correspondingly provided on the rear end surface of the front cover 9, so that the front magnetic conductive block and the front cover can be relatively fixed by the cooperation of the small circular protrusions and the small circular grooves. Three small circular protrusions are provided on the rear end surface of the rear magnetic conductive block 13, and three small circular grooves are correspondingly provided on the front end surface of the rear cover 12, so that the rear magnetic conductive block and the rear cover can be relatively fixed by the cooperation of the small circular protrusions and the small circular grooves.

[0027] In this embodiment, a threaded hole is opened in the middle of the magnetic block 13, and the rear rod of the double-rod hydraulic piston 3 has an external thread that cooperates with the threaded hole. The rear rod extends into the threaded hole and cooperates with it to achieve a fixed connection between the rear rod of the double-rod hydraulic piston and the flow channel baffle.

[0028] In this embodiment, the sleeve 10, the magnetic block 13, the magnetic tube 15, the front cover 9 and the rear cover 12 are made of DT4 electrical pure iron with high magnetic permeability; the magnetic isolation disk 14 and the magnetic isolation ring 16 are made of 6061 aluminum alloy with low magnetic permeability.

[0029] In this embodiment, a dynamic seal is provided between the double-rod hydraulic piston 3 and the hydraulic cylinder 2, and two O-rings are provided; a dynamic seal is provided between the built-in piston 6 and the damper outer cylinder 5, and two O-rings are provided; a sealing ring is provided between the wire rod 7 and the damper end cover 8; a sealing ring is provided between the front and rear side rods of the double-rod hydraulic piston 3 and the corresponding end covers; a sealing ring is provided between the hydraulic cylinder 2 and the corresponding end cover; and a sealing ring is provided between the damper outer cylinder 5 and the corresponding end cover.

[0030] In summary, the present invention proposes a magnetorheological damping element based on a serpentine magnetic circuit with a built-in piston, which can be applied to semi-active damping control, especially in the leg joints or leg sections of hydraulic machinery, to effectively suppress vibration and impact, and to compensate well for the under-damping characteristics of the hydraulic system. The present invention sets the positions of the magnetic isolation disk, the magnetic isolation ring, and the magnetic conductive cylinder to guide the direction of the magnetic circuit and thus utilize the magnetic field more effectively. The overall volume is reduced while maintaining the damping force matching the hydraulic actuator, and the adaptability is stronger.

[0031] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A magnetorheological damping element based on a meandering magnetic circuit with a built-in piston, characterized in that: It comprises a hydraulic cylinder and a magnetorheological damper, wherein the hydraulic cylinder comprises a hydraulic cylinder end cover, a hydraulic cylinder barrel, a double-rod hydraulic piston and a common end cover, and the magnetorheological damper comprises a damper outer cylinder barrel, a built-in piston, a wire rod and a damper end cover; the hydraulic cylinder end cover is installed at the front end of the hydraulic cylinder barrel, the damper end cover is installed at the rear end of the damper outer cylinder barrel, the rear end of the hydraulic cylinder barrel and the front end of the damper outer cylinder barrel are connected together through the common end cover, the built-in piston is arranged in the damper outer cylinder barrel, the double-rod hydraulic piston is arranged in the hydraulic cylinder barrel, and the front side rod of the double-rod hydraulic piston passes forward from the through hole on the hydraulic cylinder end cover, the rear side rod passes backward from the through hole on the common end cover and is connected to the front part of the built-in piston, the front end of the wire rod is connected to the rear of the built-in piston and passes backward from the through hole on the damper end cover; the hydraulic cylinder barrel is filled with hydraulic oil, and the damper outer cylinder barrel is filled with magnetorheological fluid; The built-in piston includes a sleeve, an excitation coil, a magnetic block, a magnetic isolation disk, a magnetic cylinder, a magnetic isolation ring and front and rear end covers, the front and rear end covers are respectively installed at the front and rear ends of the sleeve, the magnetic isolation disk is installed without a gap between the front and rear magnetic blocks, and are jointly arranged in the magnetic cylinder to form a flow channel baffle, the magnetic cylinder is arranged in the sleeve, the excitation coil is wound on the outer circumference of the magnetic cylinder, the front and rear ends of the magnetic cylinder are respectively embedded with magnetic isolation rings and fixed between the front and rear end covers, the front and rear center flow holes are respectively opened in the middle of the front and rear end covers, the front and rear end covers have gaps respectively between them and the flow channel baffle to form front and rear disc-shaped flow channels, the magnetic cylinder and the flow channel baffle have an annular gap and are connected to the front and rear disc-shaped flow channels at the same time, the rear rod of the double-rod hydraulic piston passes through the front center flow hole and is fixedly connected to the middle of the flow channel baffle.

2. A magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: The hydraulic cylinder end cover and the common end cover are respectively provided with oil inlet and outlet ports which are communicated with the inner cavity of the hydraulic cylinder barrel.

3. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: The front and rear end covers are fixedly connected to the sleeve by bolts to form a closed whole outside the built-in piston.

4. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: The cross-section of the annular portion of the magnetic conductive cylinder is in a "T" shape, and the cross-section of the magnetic isolation ring is in an "L" shape. The two magnetic isolation rings are respectively nested and installed at the front and rear ends of the magnetic conductive cylinder to form a coil frame for winding the excitation coil. The inner end surfaces of the front and rear end covers are provided with stepped portions, and the magnetic conductive cylinder is sealed and fixed to the stepped portions on the inner end surfaces of the front and rear end covers through the magnetic isolation rings at the front and rear ends.

5. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: The outer peripheral wall of the magnetic separator is provided with a plurality of first protrusions, and the inner peripheral wall of the magnetic conductive cylinder is correspondingly provided with a plurality of first grooves, so that the magnetic separator and the magnetic conductive cylinder can be relatively fixed by the cooperation of the first protrusions and the first grooves.

6. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: A plurality of second protrusions are arranged on the front end surface of the front magnetic conductive block, and a plurality of second grooves are correspondingly opened on the rear end surface of the front end cover, so that the front magnetic conductive block and the front end cover can be relatively fixed by the cooperation between the second protrusions and the second grooves; a plurality of third protrusions are arranged on the rear end surface of the rear magnetic conductive block, and a plurality of third grooves are correspondingly opened on the front end surface of the rear end cover, so that the rear magnetic conductive block and the rear end cover can be relatively fixed by the cooperation between the third protrusions and the third grooves.

7. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: A threaded hole is opened in the middle of the magnetic block, and the rear rod of the double-rod hydraulic piston has an external thread that matches the threaded hole. The rear rod extends into the threaded hole and matches with it to achieve a fixed connection between the rear rod of the double-rod hydraulic piston and the flow channel baffle.

8. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: There is a dynamic seal between the double-rod hydraulic piston and the hydraulic cylinder; there is a dynamic seal between the built-in piston and the damper outer cylinder.

9. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: The sleeve, magnetic conductive block, magnetic conductive cylinder and front and rear end covers are made of DT4 electrical pure iron with high magnetic permeability; the magnetic isolation disk and magnetic isolation ring are made of 6061 aluminum alloy with low magnetic permeability.

10. The magnetorheological damping element based on a meandering magnetic circuit with a built-in piston according to claim 1, characterized in that: The rear end cover is provided with a rear end cover through hole connecting the excitation coil and the outside of the built-in piston, the wire rod has an internal through hole, the front end of the wire rod is installed in the rear end cover through hole, the excitation coil passes through the internal through hole of the wire rod and is connected to an external power supply; the damper end cover is provided with a magnetorheological fluid injection hole.

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