Magnetorheological damper with self-sealing and excitation failure protection functions

Abstract

The invention discloses a magnetorheological damper with self-sealing and excitation failure protection functions. The magnetorheological damper comprises a cylinder barrel, a piston rod, a piston assembly, magnetorheological fluid and a permanent magnet sealing system. The magneto-rheological fluid sealing structure has the beneficial effects that a concentrated magnetic field is generated in the sealing gap formed by the pole teeth and the piston rod, so that the magneto-rheological fluid forms a magneto-fluid sealing layer with the self-repairing characteristic, long-acting dynamic sealing independent of external power is achieved, and the leakage problem of the magneto-rheological fluid in the reciprocating motion of the piston rod is effectively solved; the piston rod and the piston sleeve which are made of magnetic conductive materials are in magnetic conductive connection with the permanent magnet, so that the magnetic field of the permanent magnet can continuously act on the damping channel, the magnetic field of the magnet exciting coil and the magnetic field of the permanent magnet are overlapped to achieve accurate enhancement control of damping force when the magnet exciting coil works normally, and the permanent magnet independently provides a basic magnetic field when the magnet exciting coil fails. It is ensured that stable basic damping force is generated, and seamless switching from a high-performance state to a safe mode is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to a magneto-rheological damper, in particular to a magneto-rheological damper with self-sealing and excitation failure protection functions, and belongs to the technical field of damping devices. BACKGROUND

[0002] The magneto-rheological damper is widely used due to its adjustable damping force and rapid response. However, the reliability of its reciprocating dynamic seal and the single-point failure risk of the electric control system are two major technical bottlenecks. The sealing problem: during the reciprocating motion of the piston rod, the magneto-rheological fluid is easily carried out by the rod due to viscosity, resulting in continuous loss of the fluid and short service life of the seal. The traditional magnetic liquid seal is good at static or low speed, but it is difficult to cope with high-speed reciprocating conditions. The failure protection problem: the damper adjustment depends on the excitation coil. Once the coil fails due to circuit failure, power failure, or self-damage, the magnetic field disappears, the damping force is out of control, and the function is completely lost.

[0003] In the prior art, a bottom-mounted double-channel double-cylinder anti-settling magneto-rheological damper disclosed in CN109611498A adopts a double-excitation-coil design, realizes independent damping characteristics of compression and recovery strokes through independent control of the inner and outer damping channels, and utilizes the full-flow flow of the magneto-rheological fluid to produce a redispersion effect on the settled magneto-rheological fluid. Although the double-coil layout improves the controllable range of the damping force to some extent and improves the problem of magneto-rheological fluid settlement, it does not improve the dynamic sealing of the magneto-rheological fluid, nor does it consider how to maintain the basic damping function when the excitation coil fails completely. The single-point failure risk of the electric control system still exists. For example, CN107606037A discloses a magneto-rheological damper capable of improving damping force and failure safety, which adopts four excitation coils and a unique magnetic field polarization arrangement to expand the active area of the magneto-rheological fluid, thereby improving the output damping force. When a certain excitation coil is damaged, the remaining coils can still work, avoiding complete failure of the controllable output damping force. Although this design improves the reliability of the system through redundant coils, multiple coils make the structure complex and increase the cost, and the fundamental problem of leakage of the magneto-rheological fluid during the reciprocating motion of the piston rod is still not solved. On the contrary, the complex structure may introduce more potential leakage points. In summary, the existing technology either focuses on improving the sealing structure without considering electrical failure, or proposes a complex double-coil system to ensure the damping force, but ignores the failure protection of the seal, and fails to fundamentally solve the two major interrelated technical bottlenecks of dynamic sealing reliability and excitation failure safety. SUMMARY

[0004] The magnetorheological damper provided by the application has the self-sealing and magnet excitation failure protection functions, can realize long-term and reliable sealing, can provide basic damping force when the magnet coil fails, and realizes seamless switching from high performance to safety mode.

[0005] The magnetorheological damper provided by the application has the self-sealing and magnet excitation failure protection functions, can realize long-term and reliable sealing, can provide basic damping force when the magnet coil fails, and realizes seamless switching from high performance to safety mode.

[0006] As a further scheme of the application, the rod body of the piston rod is sleeved with a cover, and the cover is fixedly connected to the reinforcing cylinder and the cylinder for inserting the butt joint part of the one end of the piston rod.

[0007] As a further scheme of the application, the cylinder is provided with an end cover, the rod body of the piston rod penetrates the end cover, and the first pole shoe, the permanent magnet and the second pole shoe of the permanent magnet sealing system are all sleeved in the end cover.

[0008] As a further scheme of the application, a steel wire retainer ring and a sealing ring are further sleeved between the end cover and the cylinder, and a dustproof ring is sleeved between the end cover and the rod body of the piston rod.

[0009] As a further scheme of the application, the piston assembly comprises a piston, a piston sleeve and a piston side plate, the piston is fixedly connected to the one end of the piston rod, the piston sleeve is sleeved on the outside of the piston, and the two ends of the piston sleeve are fixedly connected with the piston side plate.

[0010] As a further scheme of the application, the rod body of the piston rod near the piston is sleeved with a buffer pad, the rod body of the piston is wound with a magnet coil, a guide ring is sleeved between the piston sleeve and the cylinder, and the magnetic field generated by the magnet coil in normal working state is superposed with the magnetic field of the permanent magnet at the damping channel of the magnetorheological fluid.

[0011] As a further scheme of the application, the cylinder body is sleeved with a lower flange plate and a lower nut, and the lower flange plate is fixedly connected with the other end of the reinforcing cylinder through the lower nut.

[0012] As a further scheme of the present application: the piston rod is fixedly connected with a stud at one end outside the cylinder barrel, the stud is sleeved with an upper nut and an upper flange plate, and the upper flange plate is fixedly connected with the stud through the upper nut, and a four-in-one shock pad and a buffer pad are further fixedly sleeved on the piston rod outside the cylinder barrel, and the buffer pad is located between the four-in-one shock pad and the upper nut.

[0013] As a further scheme of the present application: the piston rod and the piston sleeve of the piston assembly are both made of magnetic conductive material, and the piston sleeve is magnetically conductive connected with the permanent magnet of the permanent magnet sealing system through the piston rod.

[0014] As a further scheme of the present application: when the excitation coil works normally, the magnetic field of the excitation coil and the magnetic field of the permanent magnet are superposed at the damping channel.

[0015] The beneficial effects of the present application are: 1) The present application generates a concentrated magnetic field at the sealing gap formed by the pole teeth and the piston rod through the permanent magnet sealing system composed of the first pole shoe, the permanent magnet and the second pole shoe, so that the MR fluid forms a magnetic fluid sealing layer with self-repairing characteristics, realizes long-acting dynamic sealing independent of external power, and effectively solves the leakage problem of the MR fluid during the reciprocating motion of the piston rod. 2) The piston rod and the piston sleeve made of magnetic conductive material are magnetically conductive connected with the permanent magnet, and a complete magnetic circuit from the permanent magnet to the damping channel is constructed, so that the magnetic field of the permanent magnet can continuously act on the damping channel, the magnetic field of the excitation coil is superposed with the magnetic field of the permanent magnet when the excitation coil works normally to realize precise enhancement control of the damping force, and the permanent magnet independently provides a basic magnetic field when the excitation coil fails to ensure the generation of stable basic damping force, realizing seamless switching from high-performance state to safety mode; the two technical bottlenecks of low dynamic sealing reliability and poor excitation failure safety are solved at the same time through a set of magnetic circuit structure, the failure protection is realized without adding complex structures such as redundant coils, the overall structure is compact and reliable, the service life is long, and it is especially suitable for applications in safety-critical fields. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present application; Figure 2 It is a schematic diagram of the overall structure of the present application; Figure 1 It is a partial enlarged view of the permanent magnet sealing system in the present application; Figure 3 It is a partial enlarged view of the permanent magnet sealing system in the present application; Figure 1 It is a partial enlarged view of the piston assembly in the present application; Figure 4 It is a schematic diagram of the magnetic field when the coil of the MR damper fails.

[0017] In the diagram: 1. Cylinder; 2. Lower nut; 3. Lower flange; 4. Four-piece shock absorber; 5. Buffer pad; 6. Upper nut; 7. Upper flange; 8. Stud; 9. Cover; 10. Wire retaining ring; 11. First pole shoe; 12. Permanent magnet; 13. Sealing ring; 14. Second pole shoe; 15. End cap; 16. Reinforcing cylinder; 17. Dustproof ring; 18. Piston rod; 19. Buffer pad; 20. Excitation coil; 21. Guide ring; 22. Piston; 23. Piston sleeve; 24. Piston side plate. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1, as Figures 1 to 4 As shown, a magnetorheological damper with both self-sealing and excitation failure protection functions includes a cylinder 1, a piston rod 18, a piston assembly, a magnetorheological fluid, and a permanent magnet sealing system. One end of the piston rod 18 is movably inserted into the cylinder 1. A reinforcing cylinder 16 is sleeved on the outside of the cylinder 1. The piston assembly and the permanent magnet sealing system are also installed inside the cylinder 1. The permanent magnet sealing system is sleeved on the rod of the piston rod 18. The piston assembly is coaxially fixedly connected to one end of the piston rod 18. The cavity inside the cylinder 1 between the piston assembly and the permanent magnet sealing system is filled with magnetorheological fluid. The permanent magnet sealing system includes a first pole shoe 11, a permanent magnet 12, and a second pole shoe 14. The permanent magnet 12 is located between the first pole shoe 11 and the second pole shoe 14. The inner circular surfaces of the first pole shoe 11 and the second pole shoe 14 are provided with pole teeth, and the pole teeth form a sealing gap with the piston rod 18.

[0020] The permanent magnet sealing system is equipped with a self-sealing mode. The self-sealing mode of the permanent magnet sealing system works as follows: the magnetic field of the permanent magnet 12 is concentrated on the sealing gap area between the pole teeth and the piston rod 18. The magnetorheological fluid filling this gap is locked under the action of the magnetic field, forming a magnetorheological sealing layer. This layer has reduced fluidity and adheres to the component surface, blocking the leakage channels of the magnetorheological fluid, thus achieving long-term reciprocating sealing. Furthermore, the magnetorheological sealing layer has self-healing properties, dynamically filling the micro-friction gaps generated by the reciprocating motion of the piston rod, maintaining the sealing effect. The formed magnetorheological sealing layer not only effectively blocks the leakage channels of the magnetorheological fluid along the reciprocating motion direction of the piston rod 18, fundamentally solving the problem of continuous loss caused by the viscosity of the magnetorheological fluid being carried out by the piston rod 18; secondly, the magnetic field provided by the permanent magnet 12 does not rely on external power, ensuring that even in the extreme case of complete failure of the excitation coil, the basic sealing function can still be automatically maintained, preventing fluid leakage.

[0021] The permanent magnet sealing system is also configured with a failure protection mode: when the excitation coil 20 fails, the permanent magnet 12 can provide a basic magnetic field at the damping passage to generate a stable basic damping force.

[0022] In addition to all the technical features in Embodiment 1, Embodiment 2 further includes that the shank of the piston rod 18 is sleeved with a cover 9, and the cover 9 is fixedly connected to the reinforcing cylinder 16 and the cylinder 1 for inserting the butt joint part of one end of the piston rod 18. The cover 9 serves as a structural member of the end of the cylinder 1, realizing the sealing of the cylinder 1 and the external reinforcing cylinder 16 at the interface, preventing the magnetorheological fluid from leaking from the connecting gap between the cylinder 1 and the reinforcing cylinder 16, and making up for the potential weak point of the dynamic sealing. Secondly, the fixed connection of the cover 9 can better withstand the lateral force from the piston rod 18 and the vibration impact in work, preventing the loosening or deformation of the connecting part due to long-term reciprocating motion, thereby ensuring the stability of the sealing gap between the piston rod 18 and the internal permanent magnet sealing system, and indirectly maintaining the persistence of the self-sealing effect.

[0023] The cylinder 1 is provided with an end cover 15, the shank of the piston rod 18 penetrates through the end cover 15, and the first pole shoe 11, the permanent magnet 12 and the second pole shoe 14 of the permanent magnet sealing system are all sleeved in the end cover 15. The end cover 15 serves as a mounting carrier to provide a containing space for the permanent magnet sealing system, ensuring that the first pole shoe 11, the permanent magnet 12 and the second pole shoe 14 can be positioned relative to the piston rod 18, thereby ensuring the uniformity of the annular sealing gap formed by the pole teeth and the piston rod 18 in the circumferential and axial directions, which enables the magnetic energy of the permanent magnet 12 to be most effectively concentrated in the sealing area, maximizes the formation effect and sealing pressure of the magnetic fluid sealing layer, and at the same time, embeds the permanent magnet sealing system in the end cover 15, which is relatively isolated from the magnetorheological fluid in the cylinder 1 and the movement environment of the piston rod 18, reducing external interference and potential pollution.

[0024] The steel wire retainer 10 and the sealing ring 13 are also sleeved between the end cover 15 and the cylinder 1, and the dustproof ring 17 is sleeved between the end cover 15 and the shank of the piston rod 18. The steel wire retainer 10 is used for the axial positioning between the end cover 15 and the cylinder 1, preventing the end cover 15 and the integrated permanent magnet sealing system inside it from axially moving under pressure fluctuation or vibration environment. The sealing ring 13 is used to block the cooperation gap between the outer circular surface of the end cover 15 and the inner wall of the cylinder 1, avoiding the leakage of the magnetorheological fluid from the static joint surface therebetween. The dustproof ring 17 is arranged between the end cover 15 and the shank of the piston rod 18 to prevent dust, moisture and other pollutants from being brought into the damper inside with the reciprocating motion of the piston rod 18.

[0025] In addition to comprising all the technical features in Embodiment One, Embodiment Three further comprises: the piston assembly comprises a piston 22, a piston sleeve 23 and a piston side plate 24, the piston 22 is fixedly connected to one end of the piston rod 18, the piston sleeve 23 is sleeved on the outside of the piston 22, and both ends of the piston sleeve 23 are fixedly connected with the piston side plate 24.

[0026] The piston rod 18 is sleeved with a buffer pad 19 on the rod body close to the piston 22, the piston body recessed groove part is wound with an excitation coil 20, a guide ring 21 is sleeved between the piston sleeve 23 and the cylinder barrel 1, and the magnetic field generated by the excitation coil 20 when working normally is superimposed with the magnetic field of the permanent magnet 12 at the damping channel of the magnetorheological fluid. The buffer pad 19 can absorb and buffer the mechanical impact that may be generated by the piston assembly at the limit position of movement, protect the piston assembly, the piston rod 18 and the end structure of the cylinder barrel 1 from being damaged, the excitation coil 20 generates a controllable electromagnetic field when energized, and the electromagnetic field is superimposed with the constant magnetic field of the permanent magnet 12 at the damping channel of the magnetorheological fluid, which makes the damping force can be quickly and accurately continuously adjusted in a wide range, meeting the high requirements of complex vibration control on damping performance, and the guide ring 21 ensures the centration and stability of the piston assembly when reciprocating linearly in the cylinder barrel 1, reducing friction and wear.

[0027] The cylinder barrel 1 is sleeved with a lower flange plate 3 and a lower nut 2, and the lower flange plate 3 is fixedly connected with the other end of the reinforcing barrel 16 through the lower nut 2. The lower flange plate 3 and the lower nut 2 enable the damper to be conveniently connected to an external support structure or a vibration reduction device.

[0028] A stud 8 is fixedly connected to one end of the piston rod 18 outside the cylinder barrel 1, an upper nut 6 and an upper flange plate 7 are sleeved on the stud 8, and the upper flange plate 7 is fixedly connected with the stud 8 through the upper nut 6. A four-body shock pad 4 and a buffer pad 5 are also fixedly sleeved on the rod body of the piston rod 18 outside the cylinder barrel 1. The buffer pad 5 is located between the four-body shock pad 4 and the upper nut 6, so that the movement of the piston rod 18 can be effectively transmitted to the load or receive vibration excitation from the load, facilitating the installation of the damper. The four-body shock pad 4 and the buffer pad 5 provide vibration isolation and impact protection functions.

[0029] The piston rod 18 and the piston sleeve 23 of the piston assembly are both made of magnetically conductive material, and the piston sleeve 23 is magnetically conductive connected with the permanent magnet 12 of the permanent magnet sealing system through the piston rod 18, so that the magnetic force lines of the permanent magnet effectively pass through the sealing gap and the damping channel. The piston rod 18 and the piston sleeve 23 made of magnetically conductive material act as an efficient conduction bridge of the magnetic force lines. The magnetic force lines generated by the permanent magnet 12 can be conducted from the permanent magnet sealing system to the piston assembly through the magnetically conductive connection via the piston rod 18, and finally pass through the damping channel between the piston sleeve 23 and the inner wall of the cylinder 1 to form a closed magnetic circuit. Even in the case that the exciting coil 20 is completely powered off or fails, a basic magnetic field provided by the permanent magnet 12 independently still exists at the damping channel, which is sufficient to maintain a certain yield stress of the magnetic rheological fluid flowing through the damping channel, so as to generate a stable and indestructible basic damping force, thereby realizing true failure protection without external intervention and avoiding the risk of complete loss of damping force.

[0030] When the exciting coil is in normal operation, the magnetic field thereof is superimposed with the magnetic field of the permanent magnet at the damping channel. In the normal operation, the magnetic field strength at the sealing gap is enhanced, so that the self-sealing effect reaches the best state.

[0031] In the normal operation state, the piston rod 18 drives the piston assembly to reciprocate in the cylinder 1 filled with the magnetic rheological fluid, and the magnetic rheological fluid flows through the damping channel formed by the piston sleeve 23 and the inner wall of the cylinder 1. At this time, the exciting coil 20 is powered on to generate a controllable electromagnetic field, which is superimposed with the constant magnetic field generated by the permanent magnet sealing system at the damping channel, so as to accurately control the viscosity of the magnetic rheological fluid and generate a variable damping force to meet the high-performance damping requirement. At the same time, the specific sealing gap is formed between the pole teeth on the inner circular surface of the first pole shoe 11 and the second pole shoe 14 of the permanent magnet sealing system and the piston rod 18. The magnetic field of the permanent magnet 12 highly concentrates on the sealing gap, so that the magnetic rheological fluid filled therein is locked to form a magnetic fluid sealing layer with self-repairing property. When the exciting coil 20 fails or is powered off, the system automatically enters the failure protection mode. At this time, the magnetic field of the exciting coil 20 disappears, but the constant magnetic field of the permanent magnet 12 still exists. Since the piston rod 18 and the piston sleeve 23 are both made of magnetically conductive material, they form a low-magnetic-resistance magnetically conductive connection with the permanent magnet 12, and a complete magnetic circuit is constructed from the permanent magnet sealing system to the piston assembly via the piston rod 18 and through the damping channel. Even in the case of power failure, a basic magnetic field provided by the permanent magnet 12 independently still exists at the damping channel, thereby generating a stable basic damping force and preventing the complete loss of damping force.

[0032] It will be obvious to a person skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments and can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. The embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference signs in the claims should be considered as limiting the scope of the claims to the identity of the reference signs therein.

[0033] Furthermore, it should be understood that although the description is made on the basis of the embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A magneto-rheological damper with self-sealing and field failure protection functions, comprising a cylinder (1), a piston rod (18) and a piston assembly; characterized in that: Also include magnetorheological fluid and permanent magnet sealing system; One end of the piston rod (18) is movably inserted in the cylinder (1), the cylinder (1) is provided with a reinforcing cylinder (16), and the cylinder (1) is further provided with a piston assembly and a permanent magnet sealing system; The permanent magnet sealing system is sleeved on the rod of the piston rod (18), the piston assembly is coaxially fixedly connected with one end of the piston rod (18), and the cavity between the piston assembly and the permanent magnet sealing system in the cylinder (1) is filled with magnetorheological fluid; The permanent magnet sealing system comprises a first pole shoe (11), a permanent magnet (12) and a second pole shoe (14), the permanent magnet (12) is located between the first pole shoe (11) and the second pole shoe (14), the inner circular surface of the first pole shoe (11) and the second pole shoe (14) is provided with a pole tooth, and the pole tooth and the piston rod (18) form a sealing gap, and the permanent magnet sealing system is configured with a self-sealing mode.

2. The magnetorheological damper of claim 1, wherein: The rod of the piston rod (18) is sleeved with a cover (9), and the cover (9) is fixedly connected with the reinforcing cylinder (16) and the cylinder (1) for inserting the piston rod (18) at the butt joint part.

3. The magnetorheological damper of claim 1, wherein: The cylinder (1) is provided with an end cover (15), the rod of the piston rod (18) penetrates the end cover (15), and the first pole shoe (11), the permanent magnet (12) and the second pole shoe (14) of the permanent magnet sealing system are all sleeved in the end cover (15).

4. The magnetorheological damper of claim 3, wherein: The steel wire retainer (10) and the sealing ring (13) are further sleeved between the end cover (15) and the cylinder (1), and the dustproof ring (17) is sleeved between the end cover (15) and the rod of the piston rod (18).

5. The magnetorheological damper of claim 1, wherein: The piston assembly comprises a piston (22), a piston sleeve (23) and a piston side plate (24), the piston (22) is fixedly connected with one end of the piston rod (18), the piston sleeve (23) is sleeved on the outer side of the piston (22), and the both ends of the piston sleeve (23) are fixedly connected with the piston side plate (24).

6. The magnetorheological damper of claim 5, wherein: The rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is sleeved with a buffer pad (19) near the piston (22), the rod of the piston rod (18) is 7. The magnetorheological damper of claim 1, wherein: ​ 8. The magnetorheological damper of claim 1, wherein: ​ 9. The magnetorheological damper of claim 5, wherein: The piston rod (18) and the piston sleeve (23) of the piston assembly are made of magnetically conductive material, and the piston sleeve (23) is magnetically conductively connected with the permanent magnet (12) of the permanent magnet sealed system through the piston rod (18).

10. The magnetorheological damper of claim 5, wherein: When the excitation coil (20) is in normal operation, the magnetic field of the excitation coil (20) and the magnetic field of the permanent magnet are superposed at the damping channel.

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