Magnetorheological damper with asymmetric damping characteristic

Abstract

The invention relates to the technical field of damping vibration attenuation, in particular to an asymmetric damping characteristic magnetorheological damper which comprises a cylinder barrel, a piston assembly, a piston rod and magnetorheological fluid filled in the cylinder barrel. The piston assembly comprises a piston head connected with the piston rod, an excitation winding arranged in the circumferential direction of the piston head, a lower pressing plate arranged at the end, away from the piston rod, of the piston head, an upper pressing plate arranged at the end, provided with the piston rod, of the piston head, and a baffle capable of axially moving between the piston head and the upper pressing plate. A damping channel is formed between the upper pressing plate and the lower pressing plate; and the baffle is arranged at the end part of the damping channel, slides on the piston rod, can axially move in response to the flowing direction of the fluid, partially blocks the damping channel and changes the effective flowing section of the fluid passing through the damping channel. The piston has the effect of reducing the occupation of the radial space of the piston head.

Description

Technical Field

[0001] This application relates to the technical field of damping and vibration reduction, and in particular to a magnetorheological damper with asymmetric damping characteristics. Background Technology

[0002] Asymmetric damping magnetorheological dampers exhibit different compression and recovery damping characteristics, meeting the dynamic control requirements under complex operating conditions. Existing technologies for achieving asymmetric output damping force often employ the method of adding a controllable flow channel to achieve different damping characteristics during compression and recovery strokes. A throttling valve is added to the controllable flow channel; the direction of fluid movement determines the opening and closing of the valve, thus altering the opening and closing of the controllable flow channel. When the controllable flow channel is closed, the fluid movement cross-section decreases, and the damping force increases; when the controllable flow channel is open, the fluid movement cross-section increases, and the damping force decreases; thereby achieving the asymmetric damping characteristics of the damper.

[0003] In the prior art, patent CN103352956A discloses a magnetorheological damper with asymmetric controllable damping characteristics. Two damping channels are arranged between the left and right cavities separated by a piston. One is a fixed-gap damping channel near the outer wall of the piston, and the other is a controllable damping channel near the piston axis. The end of the controllable damping channel is equipped with a one-way throttling valve assembly. When the damper is compressed (liquid flows from the right cavity to the left cavity), the valve opens, and the liquid passes through both channels, resulting in a smaller damping force. When the damper returns to its original state (liquid flows from the left cavity to the right cavity), the valve closes, and the liquid passes through one channel, resulting in a larger damping force.

[0004] However, the multi-channel technology has the following disadvantages: multi-channel requires more radial space than single-channel; the piston head is generally made of a material with good magnetic permeability, the magnetic permeability of the magnetorheological fluid in the channel is less than the magnetic permeability of the piston head material, and multi-channel has greater magnetic resistance than single-channel, which will reduce the magnetic induction intensity of the damping channel.

[0005] When vibration reduction systems require damper cylinders with small inner diameters, existing multi-channel technologies are difficult to implement. Furthermore, higher magnetic reluctance necessitates more coil turns in multi-channel designs to achieve the same magnetic flux density, increasing the winding slot size, coil resistance, and overall control system energy consumption. Summary of the Invention

[0006] This application provides a magnetorheological damper with asymmetric damping characteristics, which can at least partially solve the above-mentioned technical problems.

[0007] This application provides a magnetorheological damper with asymmetric damping characteristics, employing the following technical solution: A magnetorheological damper with asymmetric damping characteristics includes a cylinder, a piston assembly, a piston rod, and a magnetorheological fluid filled within the cylinder. The piston assembly divides the cylinder cavity into an upper chamber and a lower chamber. The piston assembly includes a piston head connected to the piston rod, an excitation winding arranged circumferentially along the piston head, a lower pressure plate disposed at the end of the piston head away from the piston rod, an upper pressure plate disposed at the end of the piston head where the piston rod is mounted, and a baffle that can move axially between the piston head and the upper pressure plate. A damping channel is formed between the upper pressure plate and the lower pressure plate; The baffle is located at the end of the damping channel and slides on the piston rod. It can move axially in response to the direction of fluid flow and partially block the damping channel, thereby changing the effective flow cross section of the fluid through the damping channel.

[0008] By adopting the above technical solution, when the damper is working, the piston assembly reciprocates within the cylinder. During the compression stroke (the piston rod is pressed into the cylinder), the volume of the lower chamber decreases, the magnetorheological fluid is compressed, and the hydraulic thrust generated by its flow acts on the baffle, driving the baffle to move away from the piston head (usually upwards), thereby avoiding the end of the damping channel, keeping the flow cross-section large and the damping force small. During the recovery stroke (the piston rod is pulled out of the cylinder), the volume of the upper chamber decreases, the flow direction of the magnetorheological fluid reverses, and the hydraulic thrust pushes the baffle closer to the piston head (usually downwards), partially blocking the end of the damping channel, causing the effective flow cross-section to decrease sharply, thus generating a larger damping force. The entire process is driven by the fluid itself, requiring no external control. By cleverly utilizing the directionality of fluid mechanics through a single flow channel and a movable baffle, it achieves asymmetric characteristics of low compression damping force and high recovery damping force. Compared to the closest existing technology with a dual-flow channel design, the single-flow channel (damping channel) and baffle structure significantly reduces the radial space occupied by the piston head, allowing the damper to be made more compact and suitable for applications with smaller cylinder inner diameters. The single-flow channel design means that the magnetic lines of force need to pass through a more concentrated area of ​​low-permeability magnetorheological fluid, resulting in a shorter magnetic circuit and significantly reduced magnetic reluctance. Due to the reduced magnetic reluctance, the number of ampere-turns required to generate the same magnetic induction intensity is reduced, which means that smaller coils or lower currents can be used, reducing the resistance of the excitation winding and the energy consumption of the system. At the same time, by setting an asymmetric zero-field damping force through the mechanical structure, the requirement for "adjustable damping force multiple" is reduced, simplifying the design difficulty of the control system.

[0009] Optionally, an outer piston cylinder is also provided on the outside of the piston head. The outer piston cylinder fits against and slides relative to the cylinder. The two ends of the outer piston cylinder are respectively connected to the upper pressure plate and the lower pressure plate. An annular damping channel is formed between the outer piston cylinder and the piston head. An upper pressure plate flow channel communicating with the damping channel is opened on the upper pressure plate, and a lower pressure plate flow channel communicating with the damping channel is opened on the lower pressure plate. The baffle can partially cover the annular damping channel.

[0010] By adopting the above technical solution, the formation method and location of the damping channel are specifically defined. The piston outer cylinder and the cylinder inner wall fit tightly and slide together, forming a seal and guide. The damping channel is actually the annular gap between the inner wall of the piston outer cylinder and the outer wall of the piston head. The upper and lower pressure plate flow channels ensure that the liquid in the cavity can flow smoothly into and out of the annular damping channel. The movement range of the baffle is designed to cover the inlet or outlet of this annular channel. The piston outer cylinder connects the upper pressure plate, the lower pressure plate and the piston head into a rigid piston assembly, which is structurally robust and easy to assemble. The annular damping channel allows the magnetic field generated by the excitation winding to pass uniformly and perpendicularly through the magnetorheological fluid in the annular gap, resulting in high magnetic field utilization and significant magnetorheological effect. Based on achieving asymmetric damping, saving space and optimizing the magnetic circuit, the stability of the damper operation and the effectiveness of the magnetic field are further guaranteed.

[0011] Optionally, the damping channel is formed on the axial side of the excitation winding away from the piston rod.

[0012] By adopting the above technical solution, the damping channel is positioned outside the excitation winding. This means that the excitation winding is embedded inside the piston head, and the magnetic field it generates acts radially outward, directly acting on the magnetorheological fluid in the annular damping channel surrounding the piston head. This ensures that the magnetic field energy is concentrated to the maximum extent in the damping channel region where the magnetorheological effect needs to occur, avoiding magnetic field loss and further improving the utilization efficiency of the magnetic field and the controllable range of the damping force. The combination of the "annular channel" and "positioned outside the excitation winding" constitutes a very classic and efficient magnetorheological valve structure, providing an optimal magnetic circuit design for obtaining a powerful and adjustable magnetorheological damping force.

[0013] Optionally, the baffle slides between the upper pressure plate and the piston head, and the projected portion of the baffle covers the upper pressure plate flow channel on the upper pressure plate.

[0014] By adopting the above technical solution, the sliding pair of the baffle is set between the upper pressure plate and the piston head, and its movement will partially cover the upper pressure plate flow channel on the upper pressure plate. During the recovery stroke, the baffle moves down, partially blocking the damping channel, increasing the resistance of the liquid flowing from the upper cavity into the damping channel, thereby contributing to the increase of the recovery damping force. The baffle can not only adjust the damping force by changing the opening area at the end of the annular damping channel, but also apply an additional throttling effect by covering the upper pressure plate flow channel. These two mechanisms can work together to more significantly increase the difference in damping force between the recovery stroke and the compression stroke, and enhance the asymmetric effect. By designing the number, size and distribution of the liquid inlet holes, as well as the range covered by the baffle, the ratio of asymmetric damping forces can be designed and adjusted more precisely.

[0015] Optionally, both the upper pressure plate flow channel and the lower pressure plate flow channel are arc-shaped and have multiple channels, which are equally spaced.

[0016] By adopting the above technical solution, the shape and layout of the inlet holes have been optimized. Multiple equally spaced arc-shaped holes are used to match the annular piston assembly structure. Multiple equally spaced holes can ensure that the fluid flows into and out of the damping channel evenly, avoid the piston assembly being subjected to uneven lateral hydraulic loads, reduce the risk of uneven wear and seal failure, and improve the working stability and life of the damper. When the baffle covers these evenly distributed inlet holes, symmetrical and stable throttling can be achieved, avoiding vibration or noise caused by asymmetrical throttling.

[0017] Optionally, a protrusion is formed on the upper pressure plate, and the baffle abuts against the protrusion when it moves away from the piston head.

[0018] By adopting the above technical solution, the protrusion on the upper pressure plate acts as a mechanical limiting structure. During the compression stroke, the baffle moves upward under the push of the fluid and eventually blocks the protrusion, preventing it from moving excessively or even leaving the preset sliding range. The limiting structure ensures that the baffle is always in an effective working position, preventing it from jamming, misaligning, or colliding with other components under violent movement, thus improving the working reliability and durability of the damper. The position of the protrusion defines the limit position of the baffle during the compression stroke, thereby determining the maximum flow cross section at this time, which helps to accurately control the value of the minimum damping force (zero-field compression damping force).

[0019] Optionally, at least one of the lower pressure plate or the upper pressure plate is connected to the piston head.

[0020] By adopting the above technical solution, at least one of the lower or upper pressure plates is fixedly connected to the piston head (e.g., by thread, welding or interference fit), thereby assembling the piston head, pressure plate and piston outer cylinder into a whole; ensuring the overall structural strength and rigidity of the piston assembly, and being able to withstand various forces and torques brought about by reciprocating motion; this structure provides space and convenience for pre-installing and sealing the excitation winding inside the piston head.

[0021] Optionally, the piston outer cylinder has a chamfer on its side wall near the cylinder.

[0022] By adopting the above technical solution, a chamfer is formed at the end edge where the piston outer cylinder contacts the cylinder. The chamfer acts as a guide, making it easier for the piston assembly to be installed into the cylinder and avoiding sharp edges from scratching the inner wall of the cylinder or the seals. The chamfer also helps to form and maintain a lubricating film during operation, reducing friction and wear between the piston outer cylinder and the cylinder.

[0023] Optionally, the piston outer cylinder, the upper pressure plate, and one end of the piston head form a sliding space, and the distance between the outer wall of the sliding space and the piston rod is greater than the distance between the outer edge of the damping channel and the piston rod.

[0024] By adopting the above technical solution, the outer diameter of the sliding space is larger than the outer diameter of the damping channel, which means that more fluid acts on it, making it more sensitive and faster in responding to changes in fluid force, resulting in better dynamic performance. Furthermore, when the damping channel is blocked by the baffle, it is easier for the sliding space to contain the liquid and enter the damping channel from the side of the baffle. The larger sliding mating surface can better maintain the axial stability of the baffle movement and prevent it from tilting or getting stuck.

[0025] Optionally, a spring is provided between the upper pressure plate and the baffle.

[0026] By adopting the above technical solution, a spring is added between the baffle and the upper pressure plate. This spring is typically pre-compressed, providing a preload force to the baffle towards the piston head. The spring force sets a pressure threshold; the baffle will only move open during the compression stroke when the fluid pressure is sufficient to overcome this preload force. This allows designers to precisely adjust the magnitude of the zero-field compression damping force; it makes the asymmetric damping characteristics related not only to direction but also to flow velocity (pressure), enabling more complex damping characteristic curves; when the fluid pressure is low or changes, the spring force helps the baffle quickly and reliably return to the closed position, ensuring the immediacy of the recovery stroke damping effect.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. By setting a baffle, the damper outputs a damping force greater than the output damping force during the recovery stroke, thus achieving asymmetrical output damping characteristics. When the compression stroke and extension stroke require different output damping force ranges, the asymmetrical output can reduce the need for adjustable damping force ratios. 2. By setting a single flow channel, the difficulty of flow channel machining is adapted to cylinders with small inner diameters, and the radial space occupied is reduced. Attached Figure Description

[0028] Figure 1 This is an internal structural diagram of the damper in an embodiment of this application; Figure 2 This is a schematic diagram of the flow direction of the magnetorheological fluid during the restoration of the stroke in the embodiments of this application; Figure 3 This is a schematic diagram of the flow direction of the magnetorheological fluid during the compression stroke in an embodiment of this application; Figure 4 This is a schematic diagram of another embodiment of the present application containing a spring structure.

[0029] Reference numerals: 100, cylinder; 110, upper chamber; 120, lower chamber; 200, piston assembly; 210, piston head; 220, excitation winding; 230, lower pressure plate; 231, lower pressure plate flow channel; 240, upper pressure plate; 241, upper pressure plate flow channel; 250, baffle; 260, damping channel; 270, piston outer cylinder; 271, chamfer; 272, sliding space; 280, protrusion; 290, spring; 300, piston rod. Detailed Implementation

[0030] The following combination Figures 1 to 4 This application will be described in further detail.

[0031] This invention provides a magnetorheological damper with asymmetric damping characteristics. Its core lies in the combination of a unique movable baffle 250 and a single annular damping channel 260. The fluid itself adaptively pushes the baffle 250 to slide, thereby partially blocking the damping channel 260 and changing the flow cross section. This achieves asymmetric characteristics of small compressive damping force and large restorative damping force without the need for complex multi-channel structures and external control.

[0032] Reference Figures 1 to 3 The damper mainly includes a cylinder 100, a piston assembly 200, a piston rod 300, and a magnetorheological fluid. The piston assembly 200 is driven by the piston rod 300 to reciprocate within the cylinder 100, and its interior is divided into an upper chamber 110 and a lower chamber 120. The lower chamber 120 is located closer to the piston rod 300, while the upper chamber 110 is located on the other side.

[0033] During the compression stroke, the fluid pressure pushes the baffle 250 away from the end of the channel, opening a large flow cross section with low damping force; during the recovery stroke, the fluid pressure pushes the baffle 250 closer to and partially blocks the end of the channel, the flow cross section decreases sharply, and the damping force increases significantly.

[0034] In other embodiments, the channel can be opened on the piston head 210, which can be located inside the excitation winding 220. In this embodiment, the above method is preferred, and an annular damping channel 260 is formed by the outer cylinder and the piston head 210.

[0035] The cylinder 100 is a cylindrical structure filled with magnetorheological fluid. One end of the piston rod 300 extends into the cylinder 100, and the other end is connected to external equipment. The piston assembly 200 is fixedly installed at the end of the piston rod 300. The piston assembly 200 integrates an excitation winding 220 that generates a magnetic field, an outer piston cylinder 270 forming an annular damping channel 260, an upper pressure plate 240, a lower pressure plate 230, and a crucial axially movable baffle 250. Specifically, the piston head 210 is cylindrical and made of a high-permeability magnetic material. Its center is fixedly connected to the end of the piston rod 300 by means of threads or interference fit. The outer side wall of the piston head 210 has annular grooves evenly distributed along its circumference. The density and spacing of the annular grooves are set according to requirements. The excitation winding 220 is embedded and fixed in the annular grooves, and its wires are led out along the wire grooves inside or on the surface of the piston rod 300 and connected to an external power source. After being energized, the excitation winding 220 generates a magnetic field.

[0036] Upper pressure plate 240 and lower pressure plate 230 are respectively disposed at both ends of piston head 210. Upper pressure plate 240 is located at the end closer to piston rod 300 and has a sleeve hole. Upper pressure plate 240 is sleeved onto piston rod 300 through the sleeve hole. Lower pressure plate 230 is located at the end away from piston rod 300. At least one of lower pressure plate 230 or upper pressure plate 240 is fixed to the end of piston head 210 by means of threaded connection, pin connection or welding, thereby assembling piston head 210 and pressure plate together. The end of piston head 210 away from piston rod 300 is in contact with lower pressure plate 230. There is a gap between upper pressure plate 240 and piston head 210. An expansion groove is provided on the inner wall of piston outer cylinder 270. The distance between the opening edge of the expansion groove and the axis of piston rod 300 is greater than the distance between the outer edge of damping channel 260 and piston. The distance between the axes of rod 300 is such that the side of the expansion groove near the lower pressure plate 230 is flush with the side of the piston head 210 away from the lower pressure plate 230. The upper pressure plate 240 is embedded in the expansion groove, and a sliding space 272 is formed between the piston outer cylinder 270, the upper pressure plate 240, and the piston head 210. The baffle 250 is located in this sliding space 272. The piston outer cylinder 270 is a cylinder sleeved outside the piston head 210. Its two ends are fixedly connected to the outer edges of the upper pressure plate 240 and the lower pressure plate 230, respectively. The fixed connection can be achieved by bolting, welding, or other fixing methods, thus forming a rigid integral piston assembly 200 together with the piston head 210, the upper pressure plate 240, and the lower pressure plate 230. The outer wall of the piston outer cylinder 270 is precisely fitted with the inner wall of the cylinder 100 and can slide relative to it, serving as a guide and seal. To further facilitate assembly and reduce friction, a chamfer 271 can be formed at the end of the side wall of the piston outer cylinder 270 near the cylinder 100.

[0037] An annular gap is maintained between the inner wall of the piston outer cylinder 270 and the outer wall of the piston head 210, which constitutes the unique damping channel 260. The damping channel 260 is located radially outside the excitation winding 220, so that the magnetic field generated by the excitation winding 220 can pass through the magnetorheological fluid here efficiently and vertically.

[0038] To connect the cylinder 100 cavity with the annular damping channel 260, multiple upper pressure plate channels 241 are radially formed on the upper pressure plate 240, and multiple lower pressure plate channels 231 are radially formed on the lower pressure plate 230. These channels are preferably arc-shaped and evenly distributed circumferentially to ensure the uniformity of fluid flow and the balance of forces on the piston assembly 200.

[0039] In other embodiments, the upper pressure plate flow channel 241 and the lower pressure plate flow channel 231 may also be cylindrical, rectangular or other shaped holes, so that the overall structure of the upper pressure plate 240 or the lower pressure plate 230 is not damaged, and they are evenly spaced.

[0040] The baffle 250 is an axially sliding ring or disc that is directly fitted onto the piston rod 300 and located in the sliding space 272 formed between the upper pressure plate 240 and the end face of the piston head 210. This allows the baffle 250 to obtain a sufficiently large hydraulic action area to ensure its sensitive action, while also providing a flow path for the fluid.

[0041] The function of baffle 250 is to adaptively move in response to the fluid direction to change the effective flow cross-section. Its working principle is as follows: When the damper is in the compression stroke, the volume of the lower chamber 120 decreases, and the magnetorheological fluid flows into the damping channel 260 through the lower pressure plate channel 231. The resulting hydraulic thrust pushes baffle 250 to the left. At this time, baffle 250 disengages from the end of the damping channel 260 and the upper pressure plate channel 241, allowing the fluid to pass smoothly through a larger cross-section with a smaller damping force. To prevent excessive movement of baffle 250, a protrusion 280 can be provided on the upper pressure plate 240. When baffle 250 moves to its extreme left position, it abuts against the protrusion, providing a mechanical limiting effect. The shape of the protrusion 280 can be any shape with a plane and parallel to the contact surface of baffle 250.

[0042] When the damper is in its recovery stroke, the volume of the upper chamber 110 decreases, and the magnetorheological fluid flows through the upper pressure plate channel 241 to the damping channel 260. The hydraulic thrust generated by this flow pushes the baffle 250 to the right (closer to the piston head 210). At this time, the baffle 250 partially covers and blocks the end of the annular damping channel 260 and part of the inlet of the upper pressure plate channel 241, causing the effective flow cross section of the fluid to decrease sharply, thereby generating a large damping force.

[0043] Reference Figure 4 In other embodiments, as a preferred implementation, a spring 290 can be provided between the upper pressure plate 240 and the baffle 250. The spring 290 provides a continuous preload force to the baffle 250 in the direction of the piston head 210. This can precisely adjust the fluid pressure threshold required to open the compression stroke flow channel, thereby fine-tuning the magnitude of the zero-field compression damping force and making the damping characteristics have a certain speed correlation. At the same time, it helps the baffle 250 to quickly reset when the fluid pressure decreases.

[0044] The spring 290 can be any type of spring, such as a tower spring or a regular straight spring, and can be installed on the piston rod 300 or multiple springs can be installed on the protrusion 280.

[0045] The working process of the magnetorheological damper of this invention is clear and straightforward: during the compression stroke, the baffle 250 is open, resulting in low flow resistance and low damping force; during the recovery stroke, the baffle 250 is closed, leading to high flow resistance and high damping force. The asymmetric damping characteristics are automatically achieved through the aforementioned mechanical structure.

[0046] The single-channel design with baffle 250 greatly saves radial space, making it suitable for small cylinder diameter applications. It reduces the difficulty of opening the damping channel 260, reduces interference with the magnetic field, and reduces radial space occupation. The annular single-channel structure significantly reduces magnetic reluctance, enabling the generation of a stronger magnetic field at the same excitation ampere-turns, or lower energy consumption when generating the same magnetic field. It not only achieves asymmetric damping but also presets the asymmetric zero-field damping force mechanically, reducing the requirements for the electromagnetic adjustment range (adjustable multiple) and simplifying the control system design. The piston assembly 200 has good rigidity, the baffle 250 has movement limit protection, and the piston outer cylinder 270 has a chamfer 271. The overall structure is reliable and has a long service life. The addition of the optional spring 290 provides an additional means for fine adjustment of damping characteristics.

[0047] By setting baffle 250, the damper outputs a greater damping force during the recovery stroke than during the compression stroke, achieving asymmetrical output damping characteristics. When the compression and extension strokes require different ranges of output damping force, the asymmetrical output reduces the need for adjustable damping force ratios.

[0048] Suppose a vibration reduction system has the following requirements for the damper: at a certain piston speed, the output range of the compression damping force is 25~100N, and the output range of the recovery damping force is 110~440N.

[0049] In the design of the symmetrical damping damper, the zero-field damping force is set at 25N, the adjustable factor of the compression stroke damping force is 3 times, and the adjustable factor of the recovery stroke damping force is 16.6 times. The high adjustable factor of the recovery stroke increases the difficulty of system design.

[0050] When using the technical solution of this invention to achieve asymmetric damping characteristics, such as designing the zero-field damping force during the compression stroke to be 25N and the zero-field damping force during the recovery stroke to be 110N, then the adjustable factor of the damping force for both the compression and recovery strokes only needs to be 3. A smaller adjustable factor of the damping force reduces system design requirements and provides greater design freedom.

[0051] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A magnetorheological damper with asymmetric damping characteristics, characterized in that: The system includes a cylinder (100), a piston assembly (200), a piston rod (300), and a magnetorheological fluid filled within the cylinder (100), wherein the piston assembly (200) divides the inner cavity of the cylinder (100) into an upper cavity (110) and a lower cavity (120), characterized in that: The piston assembly (200) includes a piston head (210) connected to the piston rod (300), an excitation winding (220) arranged circumferentially along the piston head (210), a lower pressure plate (230) disposed at one end of the piston head (210) away from the piston rod (300), an upper pressure plate (240) disposed at one end of the piston head (210) where the piston rod (300) is mounted, and a baffle (250) axially movable between the piston head (210) and the upper pressure plate (240). A damping channel (260) is formed between the upper pressure plate (240) and the lower pressure plate (230). The baffle (250) is disposed at the end of the damping channel (260) and slides on the piston rod (300). It can move axially in response to the direction of fluid flow and partially block the damping channel (260), thereby changing the effective flow cross section of the fluid through the damping channel (260).

2. The magnetorheological damper with asymmetric damping characteristics according to claim 1, characterized in that: A piston outer cylinder (270) is also provided on the outside of the piston head (210). The piston outer cylinder (270) is in contact with the cylinder (100) and slides relative to it. The two ends of the piston outer cylinder (270) are respectively connected to the upper pressure plate (240) and the lower pressure plate (230). An annular damping channel (260) is formed between the piston outer cylinder (270) and the piston head (210). An upper pressure plate flow channel (241) communicating with the damping channel (260) is opened on the upper pressure plate (240), and a lower pressure plate flow channel (231) communicating with the damping channel (260) is opened on the lower pressure plate (230). The baffle (250) can partially cover the damping channel (260).

3. The magnetorheological damper with asymmetric damping characteristics according to claim 2, characterized in that: The damping channel (260) is formed on the axial side of the excitation winding (220) away from the piston rod (300).

4. The magnetorheological damper with asymmetric damping characteristics according to claim 2 or 3, characterized in that: The baffle (250) slides between the upper pressure plate (240) and the piston head (210), and the projected portion of the baffle (250) covers the upper pressure plate channel (241) on the upper pressure plate (240).

5. The magnetorheological damper with asymmetric damping characteristics according to claim 2, characterized in that: Both the upper pressure plate flow channel (241) and the lower pressure plate flow channel (231) are arc-shaped and have multiple channels, which are evenly spaced.

6. The magnetorheological damper with asymmetric damping characteristics according to claim 1, characterized in that: A protrusion (280) is formed on the upper pressure plate (240), and the baffle (250) abuts against the protrusion (280) when it is away from the piston head (210).

7. The magnetorheological damper with asymmetric damping characteristics according to claim 1, characterized in that: At least one of the lower pressure plate (230) and the upper pressure plate (240) is connected to the piston head (210).

8. The magnetorheological damper with asymmetric damping characteristics according to claim 2, characterized in that: The piston outer cylinder (270) has a chamfer (271) on the side wall near the cylinder (100).

9. The magnetorheological damper with asymmetric damping characteristics according to claim 2, characterized in that: The piston outer cylinder (270), the upper pressure plate (240), and one end of the piston head (210) form a sliding space (272), and the distance between the outer wall of the sliding space (272) and the piston rod (300) is greater than the distance between the outer edge of the damping channel (260) and the piston rod (300).

10. The magnetorheological damper with asymmetric damping characteristics according to claim 1, characterized in that: A spring (290) is provided between the upper pressure plate (240) and the baffle (250).

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