A magnetorheological vibration damper, its control method, system, and vehicle

Abstract

This invention relates to the field of magnetorheological vibration damper technology, and in particular to a magnetorheological vibration damper and its control method, system, and vehicle, comprising: an oil reservoir and a piston assembly and a floating piston slidably disposed within the oil reservoir; further comprising: a restoring force superposition component, which includes a built-in spring and a spring washer disposed at the end of the built-in spring; the built-in spring is sleeved on the piston rod, wherein, in the damper's mounted state, the built-in spring is in a pre-compressed state, and its elastic restoring force is used to at least partially offset the counterforce generated by the high-pressure gas below the floating piston; this invention, through the setting of a variable stiffness built-in spring, achieves adaptive mechanical characteristics of gentle comfort under small excitation and strong support under large excitation, enabling the vibration damper to match the force requirements of different working conditions only through the stiffness change of passive mechanical components without increasing the electromagnetic coil current.

Description

Technical Field

[0001] This invention relates to the field of magnetorheological vibration damper technology, and in particular to a magnetorheological vibration damper and its control method, system and vehicle. Background Technology

[0002] Magnetorheological dampers are intelligent damping devices that utilize the reversible changes in the rheological properties of magnetorheological fluids under the influence of a magnetic field. They are widely used in semi-active suspension systems of vehicles. The basic working principle of a magnetorheological damper is as follows: by passing current through a magnetic excitation coil embedded inside a piston, a controllable magnetic field is generated in the damping channel region. This causes the magnetorheological fluid flowing through this region to undergo a reversible change between low-viscosity flow dynamics and high-viscosity solid-like dynamics within milliseconds, thereby achieving continuous adjustment of the output damping force.

[0003] However, existing magnetorheological dampers face several technical bottlenecks in practical applications. Firstly, to compensate for volume changes caused by the piston rod's movement, magnetorheological dampers typically fill the bottom of the reservoir with high-pressure nitrogen and use a floating piston for isolation. However, the high-pressure nitrogen inevitably generates a continuous upward gas counterforce on the piston rod. This counterforce is equivalent to a gas spring connected in series in the suspension system, leading to a decrease in the vehicle's ability to filter minor road surface excitations, a deterioration in second-order ride comfort, and an impact on ride quality. Secondly, in terms of force output, existing magnetorheological dampers often fall into the dilemma of compromising between increasing the maximum damping force and simultaneously increasing the zero-field base friction resistance, thus limiting the expansion of the adjustable force range. Thirdly, to achieve a larger output damping force, a large current is usually continuously supplied to the magnetic excitation coil. The combined effect of Joule heating of the coil and heat dissipation from damping losses results in a significant temperature rise inside the damper, not only causing a degradation in the performance of the magnetorheological fluid but also adversely affecting the lifespan of the damper.

[0004] Therefore, how to design a magnetorheological vibration damper that can effectively suppress the gas backlash has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings in the prior art by proposing a magnetorheological vibration damper and its control method, system, and vehicle.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of this invention proposes a novel magnetorheological vibration damper, comprising:

[0008] An oil reservoir and a piston assembly and a floating piston slidably disposed within the oil reservoir; the piston assembly includes a piston rod;

[0009] Also includes:

[0010] A restoring force superposition assembly includes a built-in spring and a spring washer disposed at the end of the built-in spring;

[0011] The built-in spring is sleeved on the piston rod. When the shock absorber is installed in the vehicle, the built-in spring is in a pre-compressed state, and its elastic restoring force is used to at least partially offset the counterforce generated by the high-pressure gas below the floating piston.

[0012] Furthermore, the piston assembly also includes a piston and a magnetic excitation coil, which can generate a magnetic field when energized to adjust the damping force;

[0013] It also includes a guide, which is disposed at one end of the oil reservoir, for guiding and sealing the piston rod;

[0014] The floating piston is used to divide the oil reservoir into a working chamber for containing magnetorheological fluid and a pressure chamber for filling with high-pressure gas.

[0015] Furthermore, the spring washer includes a first spring washer and a second spring washer, which are respectively disposed at both ends of the built-in spring along the axial direction to bear and transmit the spring force;

[0016] The first spring washer is movably sleeved on the piston rod and can slide along the piston rod axially, while the second spring washer is disposed on the guide or the piston rod.

[0017] Furthermore, in the installed state, one end face of the piston contacts one end of the built-in spring through the first spring washer or the second spring washer, so that the built-in spring is in the pre-compression state.

[0018] Furthermore, the built-in spring is a variable stiffness spring, which has a first stiffness in the early part of the compression stroke and a second stiffness in the later part of the compression stroke, and the second stiffness is greater than the first stiffness.

[0019] A second aspect of this invention provides a control method for a magnetorheological vibration damper, applied to the aforementioned magnetorheological vibration damper, specifically comprising:

[0020] Based on the target value of the overall damping force required by the vehicle, obtain the real-time mechanical restoring force value provided by the built-in spring under its current compression state;

[0021] The difference between the overall damping force target value and the real-time mechanical restoring force value is calculated to obtain the magnetorheological damping force requirement value;

[0022] Based on the required magnetorheological damping force, a first control current is output to the magnetic excitation coil, wherein the intensity of the first control current is less than the intensity of the second control current required to achieve the target value of the overall damping force without the built-in spring.

[0023] Furthermore, it also includes:

[0024] The force-displacement characteristic curve of the built-in spring is pre-calibrated;

[0025] The real-time mechanical restoring force value is obtained by looking up a table in real time by detecting the displacement of the piston rod.

[0026] A third aspect of the present invention provides a drive control system for a magnetorheological vibration damper, used to control the magnetic excitation coil of the aforementioned magnetorheological vibration damper, comprising:

[0027] A bidirectional current detection module is used to detect the actual current in the magnetic excitation coil in real time;

[0028] The magnetic flux calculation module is used to estimate the actual magnetic flux of the magnetic excitation coil in real time based on the actual current and coil parameters.

[0029] A cascaded PI controller, comprising an outer flux control loop and an inner current control loop;

[0030] The outer loop flux control loop receives the target flux and compares it with the actual flux to output the target current to the inner loop current control loop;

[0031] The inner current control loop receives the target current and compares it with the actual current to generate a bidirectional drive signal;

[0032] The actuator drive module receives the bidirectional drive signal and outputs bidirectional current to the magnetic excitation coil.

[0033] Furthermore, when the control signal indicates that the damping force needs to be reduced rapidly, the inner loop current control loop generates a reverse drive signal, causing the actuator drive module to output a reverse pulse current to actively accelerate the collapse of the magnetic field inside the magnetic excitation coil.

[0034] A fourth aspect of the present invention also provides a vehicle comprising a vehicle body and a suspension system, the suspension system comprising the novel magnetorheological damper described above, and / or applying the control method described above, and / or being equipped with the drive control system described above.

[0035] The present invention proposes a magnetorheological vibration damper, its control method, system, and vehicle, the advantages of which are as follows:

[0036] When a vehicle is driving on a good road surface and encounters minor road surface excitation, the vibration amplitude of the piston rod is small, and the compression of the built-in spring is mainly in the early part of the compression stroke. At this time, the low stiffness characteristic makes the additional mechanical force generated by the built-in spring relatively gentle, and will not transmit too much impact to the vehicle body due to the spring being too stiff, thus ensuring the smoothness and ride comfort of the vehicle under minor excitation conditions.

[0037] The variable stiffness built-in spring design achieves adaptive mechanical characteristics, providing gentle comfort under low excitation and strong support under high excitation. This allows the vibration damper to match the force requirements of different working conditions by only changing the stiffness of passive mechanical components without increasing the current of the electromagnetic coil, further leveraging the technical advantage of the synergistic output of mechanical and electromagnetic forces of this invention. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of a magnetorheological vibration damper proposed in this invention;

[0039] Figure 2 This is a schematic diagram of the system structure of a magnetorheological vibration damper proposed in this invention;

[0040] In the diagram: 1. Oil reservoir; 11. Working chamber; 12. Pressure chamber; 2. Piston assembly; 21. Piston rod; 22. Piston; 3. Floating piston; 4. Restoring force superposition assembly; 41. Built-in spring; 42. Spring washer; 5. Guide. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] Example 1

[0043] Reference Figure 1 A novel magnetorheological vibration damper includes:

[0044] An oil reservoir 1 and a piston assembly 2 and a floating piston 3 slidably disposed within the oil reservoir 1; the piston assembly 2 includes a piston rod 21;

[0045] Specifically, the oil reservoir 1 is the main housing of the shock absorber, with a cylindrical structure. Its interior forms a cavity to contain the liquid medium and provide damping. The inner diameter of the oil reservoir 1 typically ranges from 36mm to 54mm, and its length can be adjusted to suit specific vehicle models and installation space requirements. One end of the oil reservoir 1 is used to mount the piston rod 21 and guide, while the other end is a closed structure.

[0046] The piston assembly 2 is slidably disposed inside the oil reservoir 1, serving as the core moving component of the shock absorber. The piston assembly 2 includes a piston rod 21. The piston rod 21 is a slender rod-shaped structure that can reciprocate along the axial direction of the oil reservoir 1. One end of the rod is connected to the piston, and the other end extends to the outside of the oil reservoir 1 for connection with the vehicle body connecting parts of the vehicle suspension system.

[0047] The floating piston 3 is slidably disposed within the oil reservoir 1, located below the piston assembly 2. The floating piston 3 divides the inner cavity of the oil reservoir 1 into two isolated areas: the upper area is a working chamber for containing the magnetorheological fluid, and the lower area is a pressure chamber for filling with inert gases such as high-pressure nitrogen. The floating piston 3 can slide up and down according to pressure changes on both sides, balancing the volume and compensating for volume changes caused by the piston rod's movement. During operation, the high-pressure gas in the pressure chamber exerts an upward thrust on the floating piston 3. This thrust is transmitted to the piston assembly 2 through the liquid medium and ultimately to the vehicle body via the piston rod 21, forming a gas reaction force.

[0048] It also includes: a restoring force superposition component 4, which includes a built-in spring 41 and a spring washer 42 disposed at the end of the built-in spring 41;

[0049] The built-in spring 41 is sleeved on the piston rod 21. When the shock absorber is installed, the built-in spring is in a pre-compressed state, and its elastic restoring force is used to at least partially offset the counterforce generated by the high-pressure gas below the floating piston 3.

[0050] Specifically, the direction of the elastic restoring force is opposite to the direction of the gas counterforce generated by the high-pressure gas below the floating piston 3. Specifically, the high-pressure gas counterforce is upward, pushing the piston rod 21 outward; while the elastic restoring force generated by the pre-compression of the built-in spring 41 is downward, pushing the piston rod 21 inward. These two forces at least partially cancel each other out on the piston assembly 2, significantly reducing the net counterforce ultimately transmitted to the vehicle body connector through the piston rod 21.

[0051] In other words, in traditional magnetorheological dampers, high-pressure nitrogen gas is necessary to compensate for the volume change caused by the piston rod's movement. However, this high-pressure gas generates a continuous upward gas counterforce on the piston rod. This counterforce is physically equivalent to a gas spring connected in series in the suspension system. Its added stiffness causes the vehicle body to vibrate at high frequencies when encountering minor road surface excitations. This invention, by setting a pre-compressed built-in spring 41, actively counteracts the gas counterforce using mechanical spring force, achieving source cancellation in the force transmission path. This effectively reduces the net counterforce transmitted to the vehicle body, improves vehicle ride comfort, and especially enhances the vehicle's ability to filter minor road surface excitations.

[0052] It should be noted that the number of spring washers 42, their specific arrangement, and their fixing relationship with the guide or piston rod, etc., described in this embodiment will be further elaborated in subsequent embodiments. This embodiment only describes the core inventive point of claim 1.

[0053] In some embodiments, the piston assembly 2 of the present invention further includes a piston 22 and a magnetic excitation coil. When energized, the magnetic excitation coil can generate a magnetic field to adjust the damping force. A damping channel for the magnetorheological fluid to flow is formed between the outer peripheral surface of the piston 22 and the inner wall of the oil reservoir 1. The magnetic excitation coil is embedded inside the piston 22. After being energized, it can generate a controllable magnetic field in the damping channel region, causing the magnetorheological fluid flowing through this region to undergo a rheological effect, thereby achieving continuous adjustment of the damping force. The larger the current, the stronger the magnetic field, and the greater the output damping force; conversely, decreasing the current reduces the damping force.

[0054] It also includes a guide 5, which is disposed at one end of the oil reservoir 1, for guiding and sealing the piston rod 21. Of course, the guide 5 is provided with a sealing element inside or at its end for sealing the annular gap between the piston rod 21 and the oil reservoir 1 to prevent the magnetorheological fluid from leaking out and external contaminants from entering. Its specific structure and principle are conventional technical means for those skilled in the art, and will not be elaborated here.

[0055] The floating piston 3 is used to divide the oil reservoir 1 into a working chamber 11 for containing magnetorheological fluid and a pressure chamber 12 for filling high-pressure gas. The floating piston 3 divides the inner cavity of the oil reservoir 1 into two isolated chambers: the upper chamber is the working chamber 11 for containing magnetorheological fluid, and the lower chamber is the pressure chamber 12 for filling high-pressure gas. During the operation of the shock absorber, when the piston rod 21 enters or exits the working chamber 11, causing a change in volume, the floating piston 3 changes the volume of the pressure chamber 12 accordingly by sliding up and down to compensate for the volume difference caused by the change in the piston rod volume and maintain the pressure balance inside the system.

[0056] In an optional embodiment, the spring washer 42 of the present invention includes a first spring washer and a second spring washer, which are respectively disposed at both ends of the built-in spring along the axial direction to bear and transmit the spring force;

[0057] The first spring washer is movably sleeved on the piston rod and can slide along the piston rod axially, while the second spring washer is disposed on the guide 5 or the piston rod 21.

[0058] Specifically, in this embodiment, under the vehicle loading state, one end face of the piston 22 contacts one end of the built-in spring 41 through the first spring washer or the second spring washer, so that the built-in spring 41 is in the pre-compression state.

[0059] The establishment of this pre-compression state depends on the force transmission path between the piston 22, the spring washer 42, and the built-in spring 41. The spring washer 42 plays the role of bearing and uniformly transmitting the spring force in this path, avoiding direct point contact or line contact between the end of the built-in spring 41 and the end face of the piston 22, thereby improving the stress conditions and reducing stress concentration and wear risk.

[0060] The elastic restoring force generated by the built-in spring 41 in this pre-compressed state is directed downward along the piston rod 21 axis. This force is used to at least partially counteract the upward counterforce generated by the high-pressure gas below the floating piston 3, significantly reducing the net counterforce transmitted to the vehicle body connecting parts and improving ride comfort.

[0061] Furthermore, based on the above embodiments, the built-in spring 41 in this invention is a variable stiffness spring, which has a first stiffness in the early part of the compression stroke and a second stiffness in the later part of the compression stroke, and the second stiffness is greater than the first stiffness.

[0062] Specifically, when the vehicle is driving on a good road surface and encounters a small road surface excitation, the vibration amplitude of the piston rod 21 is small, and the compression of the built-in spring 41 is mainly in the early part of the compression stroke. At this time, the low stiffness characteristic makes the additional mechanical force generated by the built-in spring 41 relatively gentle, and will not transmit too much impact to the vehicle body due to the spring being too stiff, thereby ensuring the smoothness and ride comfort of the vehicle under small excitation conditions.

[0063] When the vehicle is driving on rough roads or under aggressive maneuvering, the vibration amplitude of the piston rod 21 increases significantly, and the compression of the built-in spring 41 enters the later stage of the compression stroke. At this time, the intervention of the high stiffness section enables the built-in spring 41 to quickly generate a large mechanical restoring force, which effectively superimposes with the electromagnetic damping force generated by the energized magnetic excitation coil. This significantly increases the maximum output damping force of the shock absorber under extreme conditions, expands the overall adjustable force range of the shock absorber, and thus improves the vehicle's handling stability and driving safety under high excitation conditions.

[0064] In summary, the variable stiffness built-in spring 41 achieves adaptive mechanical characteristics of gentle comfort under small excitation and strong support under large excitation. This allows the vibration damper to match the force requirements of different working conditions by only changing the stiffness of passive mechanical components without increasing the current of the electromagnetic coil, further leveraging the technical advantage of the synergistic output of mechanical and electromagnetic forces of this invention.

[0065] Example 2

[0066] The second aspect of this invention proposes a control method for a magnetorheological vibration damper, applied to the aforementioned magnetorheological vibration damper, specifically including the following steps:

[0067] S1. Based on the target value of the overall damping force required by the vehicle, obtain the real-time mechanical restoring force value provided by the built-in spring 41 under its current compression state;

[0068] Specifically, during vehicle operation, the suspension system calculates and generates a target value of overall damping force F_total in real time based on factors such as vehicle posture, road surface excitation, and driver's control intentions. This target value of overall damping force represents the total restoring damping force that the shock absorber needs to output at the current moment.

[0069] Simultaneously, the real-time mechanical restoring force value F_spring provided by the built-in spring 41 under its current compression state is obtained. Since the built-in spring 41 is fitted onto the piston rod 21, its compression is directly related to the displacement of the piston rod 21. Therefore, the current mechanical restoring force value F_spring can be calculated or obtained by detecting the real-time displacement of the piston rod 21 and combining it with the known force-displacement characteristics of the built-in spring 41, i.e., the spring stiffness curve.

[0070] S3. Calculate the difference between the overall damping force target value and the real-time mechanical restoring force value to obtain the magnetorheological damping force requirement value;

[0071] After obtaining the overall damping force target value F_total and the real-time mechanical restoring force value F_spring, the difference between the two is calculated to obtain the magnetorheological damping force requirement value F_mr, that is:

[0072] F_mr = F_total - F_spring

[0073] The difference F_mr represents the force gap that needs to be filled by generating electromagnetic damping force through energizing the magnetic excitation coil after deducting the mechanical force already provided by the built-in spring 41.

[0074] S3. Based on the required magnetorheological damping force, output a first control current to the magnetic excitation coil, wherein the intensity of the first control current is less than the intensity of the second control current required to achieve the target value of the overall damping force without the built-in spring 41.

[0075] After determining the required magnetorheological damping force F_mr, the control current required to output to the magnetic excitation coil to achieve the required damping force F_mr is calculated or obtained from a table based on the pre-calibrated force-current characteristic curve of the magnetorheological damper. This control current is denoted as the first control current. .

[0076] It is important to note that in a conventional magnetorheological damper without a built-in spring 41, to achieve the same overall damping force target value F_total, the magnetic excitation coil needs to bear the entire damping force output alone. The required control current is denoted as the second control current. .

[0077] In the control method of this invention, since the built-in spring 41 has provided a portion of the mechanical restoring force F_spring (F_spring > 0), the required magnetorheological damping force F_mr is always less than the overall damping force target value F_total. Therefore, the required output first control current... The intensity must be less than the second control current. The strength, that is:

[0078]

[0079] This current reduction has a direct and significant technical effect. The magnetic excitation coil generates Joule heat during energization, and its heating power P is proportional to the square of the current I; P = Where R is the coil resistance. Therefore, the first control current... Relative to the second control current Even a slight reduction in the current will result in a significant decrease in the coil's heating power. For example, if the built-in spring 41 can share 30% of the total damping force requirement, i.e., F_spring = 0.3 × F_total, then the magnetorheological damping force requirement F_mr will decrease to 0.7 × F_total; assuming that the force value and the current have an approximately linear relationship, then... Approximately reduced to The heat output is reduced by about 70%, and the coil heating power P drops to about 49% (0.7² ≈ 0.49), meaning the heat output is reduced by about half.

[0080] In summary, the control method of this embodiment reduces the current flowing through the magnetic excitation coil by incorporating the passive mechanical force of the built-in spring 41 into the overall planning of the total force distribution at the control strategy level. This effectively reduces the heat accumulation inside the vibration damper, slows down the performance degradation of the magnetorheological fluid caused by high temperature, and improves the service life and working condition adaptability of the vibration damper.

[0081] Furthermore, the present invention also includes:

[0082] The force-displacement characteristic curve of the built-in spring 41 is pre-calibrated;

[0083] The real-time mechanical restoring force value is obtained by looking up a table in real time by detecting the displacement of the piston rod 21.

[0084] Before the shock absorber is installed on the vehicle or shipped from the factory, the force value of the built-in spring 41 can be calibrated through bench testing. During the calibration process, different displacement amounts are applied to the built-in spring 41 with different compression strokes, and the spring reaction force value corresponding to each displacement is measured and recorded, thereby establishing a complete force-displacement characteristic curve. For the aforementioned embodiment using a variable stiffness spring, this characteristic curve exhibits different slopes in the first and second stiffness segments, respectively; this characteristic curve can be stored in the vehicle's suspension control unit (ECU) in the form of a data table, fitting formula, or mathematical model.

[0085] During the actual operation of the shock absorber, the piston rod 21 undergoes axial displacement as the suspension moves. A displacement sensor (e.g., a linear displacement sensor installed between the piston rod 21 and the oil reservoir 1, or utilizing the vehicle's existing height sensor) located inside the shock absorber or on the vehicle's suspension system detects the current displacement position of the piston rod 21 in real time. Based on this real-time displacement value, the suspension control unit retrieves a pre-stored force-displacement characteristic curve and quickly obtains the real-time mechanical restoring force F_spring provided by the built-in spring 41 under the current compression state through table lookup or formula calculation.

[0086] Example 3

[0087] Reference Figure 2 This embodiment also proposes a drive control system for a magnetorheological vibration damper, used to control the magnetic excitation coil of the aforementioned magnetorheological vibration damper, specifically including:

[0088] A bidirectional current detection module is used to detect the actual current in the magnetic excitation coil in real time. This module can sample the voltage across a precision sampling resistor connected in series in the magnetic excitation coil circuit, and calculate the real-time coil current value after amplification and analog-to-digital conversion. Unlike conventional unidirectional current detection, this module has bidirectional current detection capability, which can detect both the forward drive current and the reverse pulse current during the subsequent active demagnetization process, thereby providing a complete and accurate current feedback signal for the inner loop current control loop.

[0089] The flux calculation module is used to estimate the actual magnetic flux of the excitation coil in real time based on the actual current and coil parameters. The coil parameters may include the number of turns, magnetic circuit geometry, and the permeability characteristics of the core material. The flux calculation module can internally preset a current-flux mapping model based on electromagnetic field theory or finite element analysis, or it can establish a lookup table model using experimental calibration data. This module converts the actual current into an actual magnetic flux output, providing a flux feedback signal to the outer loop flux control loop.

[0090] The cascaded PI controller consists of an outer flux control loop and an inner current control loop. The cascaded PI controller is the core decision-making unit of this drive control system. It adopts a cascaded dual-loop control architecture, which is composed of two parts connected in series: an outer flux control loop and an inner current control loop.

[0091] The outer loop flux control loop is a closed-loop regulation circuit for flux. This outer loop receives a target flux setpoint from the vehicle dynamics controller. This target flux represents the magnetic field strength required by the excitation coil to achieve the desired damping force under the current operating conditions. The outer loop flux control loop compares the received target flux with the actual flux fed back from the flux calculation module, calculates the flux deviation, processes it through a PI controller, and outputs a target current value to the inner loop current control loop. The control objective of the outer loop is to eliminate the steady-state error between the target flux and the actual flux, ensuring that the magnetic field establishment process accurately tracks the damping force requirement.

[0092] The inner current control loop is a closed-loop regulation circuit for the current. This inner loop receives the target current value output from the outer loop and compares it with the actual current fed back from the bidirectional current detection module. It calculates the current deviation, processes it through a PI regulator, and generates a bidirectional drive signal containing both direction and amplitude information. The control objective of the inner loop is to achieve rapid and accurate current tracking, ensuring that the actual current in the magnetic excitation coil can follow the target current changes given by the outer loop in real time.

[0093] By using the outer loop flux control system to directly control magnetic flux, this invention bypasses the intermediate assumption of current-to-magnetic flux transition in traditional control methods. In traditional current control, the controller assumes a stable linear relationship between current and magnetic flux. However, in reality, the hysteresis, eddy current, and remanence effects of the core material cause the establishment and decay of magnetic flux to lag behind current changes, resulting in a delay in damping force output. This invention uses magnetic flux as the final controlled variable and forms a closed loop through flux feedback, ensuring that the actual output magnetic field always accurately follows the target magnetic flux, thus eliminating the adverse effects of hysteresis and remanence at the control principle level.

[0094] The outer loop flux control loop receives the target flux and compares it with the actual flux to output the target current to the inner loop current control loop;

[0095] The inner current control loop receives the target current and compares it with the actual current to generate a bidirectional drive signal;

[0096] The actuator drive module receives the bidirectional drive signal and outputs bidirectional current to the magnetic excitation coil. This module is typically implemented using an H-bridge circuit or a similar full-bridge topology, and has the ability to output controllable current to the magnetic excitation coil in both positive and negative directions. When the inner loop outputs a positive drive signal, the actuator drive module outputs a positive current to establish the target magnetic field; when the inner loop outputs a negative drive signal, the actuator drive module can output a reverse current to achieve rapid demagnetization. This bidirectional current output capability is the key hardware foundation of the control system of this invention, supporting the subsequent implementation of the active demagnetization function.

[0097] Based on the above embodiments, in this invention, when the control signal indicates that the damping force needs to be reduced quickly, the inner loop current control loop generates a reverse drive signal, causing the actuator drive module to output a reverse pulse current to actively accelerate the collapse of the magnetic field inside the magnetic excitation coil.

[0098] Specifically, during vehicle operation, when the suspension controller determines that the shock absorber needs to quickly unload the damping force based on the operating conditions—for example, when the vehicle rapidly transitions from compression stroke to recovery stroke, or during transient conditions where it switches from a high-damping state to a low-damping state—the control system sends a command to the cascaded PI controller to rapidly reduce the damping force. At this time, the target magnetic flux of the outer loop flux control loop is quickly set to a minimum value close to zero.

[0099] Under conventional control methods, even if the target magnetic flux is set to zero, the demagnetization process of the magnetic excitation coil still requires a certain amount of time, relying solely on natural discharge and the natural decay of the magnetic field. This is because the inherent remanence and eddy current effects of the core material hinder the rapid decay of the magnetic field, causing the magnetorheological fluid to maintain a certain high viscosity in the damping channel. This prevents the damping force from decreasing in a timely manner, resulting in a lag in force response and affecting the precision of vehicle handling.

[0100] To address the aforementioned issues, in this embodiment, upon receiving a control command to rapidly unload the damping force, the inner loop current control loop actively generates a reverse drive signal. Unlike the positive current output during normal excitation, the polarity of this reverse drive signal is set to be opposite to the direction of the normal excitation current. After receiving this reverse drive signal, the actuator drive module applies a brief negative voltage pulse to the excitation coil, establishing a reverse current in the coil. This forcibly drives the magnetic domains inside the iron core to flip in a disordered direction, thereby actively accelerating the decay of the magnetic field.

[0101] This active demagnetization process can be understood as a forced magnetic field collapse mechanism: by applying a reverse voltage / current pulse, a magnetomotive force opposite to the direction of the residual magnetic field is injected into the core material, forcing the residual magnetic field to return to zero or drop to a negligible level in a very short time. Compared to the passive method of relying solely on natural demagnetization, active demagnetization significantly shortens the time for the magnetic field to disappear, typically completing the process in the range of microseconds to milliseconds.

[0102] This active demagnetizing function fundamentally solves the response lag problem caused by core hysteresis and residual magnetism in magnetorheological vibration dampers, enabling the damping force to quickly follow the unloading direction and significantly improving the response speed and force control accuracy of the vibration damper across the entire operating range.

[0103] Example 4

[0104] This embodiment also proposes a vehicle, specifically including a vehicle body and a suspension system. The suspension system includes the novel magnetorheological damper described above, and / or applies the control method described above, and / or is equipped with the drive control system described above.

[0105] Specifically, the vehicle in this embodiment can be a passenger car, commercial vehicle, off-road vehicle, or any wheeled vehicle with an independent or non-independent suspension structure. The vehicle body is the main load-bearing structure of the vehicle, and the suspension system is connected between the vehicle body and the wheels to transmit the forces and torques between the wheels and the vehicle body, buffer road impacts, and ensure the vehicle's handling stability and ride comfort.

[0106] The magnetorheological damper used in the suspension system is the novel magnetorheological damper described in Embodiment 1. This damper has a restoring force superposition component 4, which can at least partially offset the gas counterforce generated by the high-pressure gas below the floating piston 3 through the pre-compression elastic restoring force of the built-in spring 41, thereby reducing the net counterforce transmitted to the vehicle body, improving the ride comfort of the vehicle, and especially enhancing the vehicle's ability to filter out minor road surface excitations.

[0107] Meanwhile, in vehicles employing the aforementioned control method, the suspension control unit incorporates the real-time mechanical restoring force provided by the built-in spring 41 into the overall damping force distribution calculation when calculating the required control current for the shock absorber. This ensures that the first control current required by the magnetic excitation coil is always less than the second control current required without the built-in spring. The direct effect of this control strategy at the vehicle level is that, while achieving the same vehicle body posture control, the average operating current of the coil is significantly reduced, resulting in a substantial decrease in heat generation. The resulting vehicle-level benefits include: the mitigation of shock absorber thermal decay allows the suspension system to maintain stable damping characteristics under all weather and operating conditions, improving the durability and consistency of the vehicle chassis handling performance; simultaneously, the reduction in shock absorber power consumption also contributes to the overall vehicle energy consumption level, which is particularly helpful for extending the driving range of electric vehicles.

[0108] Furthermore, in vehicles equipped with the aforementioned drive control system, the cascaded PI controller uses magnetic flux as the direct control target, enabling rapid and precise response to the vehicle dynamic controller's commands for both the establishment and unloading of damping force in the shock absorbers. Especially when the vehicle requires rapid switching of damping force output from the shock absorbers under aggressive driving conditions, the intervention of the active demagnetizing function significantly shortens the damping force unloading time, effectively eliminating the force tailing phenomenon caused by residual magnetism and hysteresis effects. This ensures real-time tracking between damping force output and vehicle attitude requirements, thereby improving the vehicle's transient handling response and driving safety.

[0109] It should be noted that the aforementioned structure, control method, and drive control system are not mutually exclusive, but can be flexibly combined according to vehicle positioning and configuration requirements. For example, in basic configuration models, only a mechanical structure with built-in springs can be used to passively cancel out counterforce and expand the force range; in mid-to-high-end configuration models, a collaborative control method can be added on top of the hardware to further achieve energy saving and temperature control; in flagship configuration models, the collaborative control method and the magnetic flux guided drive control system can be fully integrated to achieve comprehensive optimization of response speed, control accuracy, and energy consumption performance.

[0110] In summary, the vehicle provided in this embodiment, through hardware innovation of the magnetorheological damper integrated in the suspension system, optimization of the control method, and upgrade of the drive control system, improves ride comfort while reducing the energy consumption and heat load of the damper, and improves the control response speed, thus achieving a comprehensive improvement in comfort, handling, and durability.

[0111] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A novel magnetorheological vibration damper, comprising: An oil reservoir (1) and a piston assembly (2) and a floating piston (3) slidably disposed within the oil reservoir (1); the piston assembly (2) includes a piston rod (21). Its characteristic is that it further includes: The restoring force superposition component (4) includes a built-in spring (41) and a spring washer (42) disposed at the end of the built-in spring (41). The built-in spring (41) is sleeved on the piston rod (21). When the shock absorber is installed, the built-in spring is in a pre-compressed state, and its elastic restoring force is used to at least partially offset the counterforce generated by the high-pressure gas below the floating piston (3).

2. The magnetorheological vibration damper according to claim 1, characterized in that: The piston assembly (2) also includes a piston (22) and a magnetic excitation coil, which can generate a magnetic field to adjust the damping force when energized; It also includes a guide (5), which is disposed at one end of the oil reservoir (1) to provide guidance and sealing for the piston rod (21); The floating piston (3) is used to divide the oil reservoir (1) into a working chamber (11) for containing magnetorheological fluid and a pressure chamber (12) for filling high-pressure gas.

3. The magnetorheological vibration damper according to claim 1, characterized in that: The spring washer (42) includes a first spring washer and a second spring washer, which are respectively disposed at both ends of the built-in spring along the axial direction to bear and transmit the spring force; The first spring washer is movably sleeved on the piston rod and can slide along the piston rod axially, while the second spring washer is disposed on the guide (5) or the piston rod (21).

4. A magnetorheological vibration damper according to claim 3, characterized in that: In the vehicle-mounted state, one end face of the piston (22) contacts one end of the built-in spring (41) through the first spring washer or the second spring washer, so that the built-in spring (41) is in the pre-compression state.

5. A magnetorheological vibration damper according to claim 3, characterized in that: The built-in spring (41) is a variable stiffness spring, which has a first stiffness in the early part of the compression stroke and a second stiffness in the later part of the compression stroke, and the second stiffness is greater than the first stiffness.

6. A control method of a magneto-rheological damper, applied to the magneto-rheological damper according to any one of claims 1 to 5, characterized in that, include: Based on the target value of the overall damping force required by the vehicle, obtain the real-time mechanical restoring force value provided by the built-in spring (41) under its current compression state; The difference between the overall damping force target value and the real-time mechanical restoring force value is calculated to obtain the magnetorheological damping force requirement value; According to the required value of the magnetorheological damping force, a first control current is output to the magnetic excitation coil, wherein the intensity of the first control current is less than the intensity of the second control current required to achieve the target value of the overall damping force without the built-in spring (41).

7. The control method according to claim 6, characterized by Also includes: The force-displacement characteristic curve of the built-in spring (41) is pre-calibrated; The real-time mechanical restoring force value is obtained by looking up a table in real time by detecting the displacement of the piston rod (21).

8. A drive control system of a magneto-rheological damper for controlling a magnetic exciting coil of the magneto-rheological damper according to any one of claims 1 to 5, characterized in that, include: A bidirectional current detection module is used to detect the actual current in the magnetic excitation coil in real time; The magnetic flux calculation module is used to estimate the actual magnetic flux of the magnetic excitation coil in real time based on the actual current and coil parameters. A cascaded PI controller, comprising an outer flux control loop and an inner current control loop; The outer loop flux control loop receives the target flux and compares it with the actual flux to output the target current to the inner loop current control loop; The inner current control loop receives the target current and compares it with the actual current to generate a bidirectional drive signal; The actuator drive module receives the bidirectional drive signal and outputs bidirectional current to the magnetic excitation coil.

9. The drive control system according to claim 8, characterized by When the control signal indicates that the damping force needs to be reduced quickly, the inner loop current control loop generates a reverse drive signal, causing the actuator drive module to output a reverse pulse current to actively accelerate the collapse of the magnetic field inside the magnetic excitation coil.

10. A vehicle, characterized in that, The vehicle includes a body and a suspension system, the suspension system including a novel magnetorheological damper as described in any one of claims 1 to 5, and / or, applies the control method as described in claim 6 or 7, and / or is equipped with a drive control system as described in claim 8 or 9.

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