CDC shock absorber with negative stiffness assembly, suspension system and vehicle

Abstract

The invention discloses a CDC shock absorber with a negative stiffness assembly, a suspension system and a vehicle, and the CDC shock absorber comprises a double-cylinder shock absorber body which comprises an outer cylinder and an inner cylinder filled with shock absorber oil; the piston assembly comprises a piston arranged in the inner cylinder and a piston rod penetrating through the outer cylinder; the electromagnetic valve system comprises double electromagnetic valves and corresponding bypass oil ways, wherein the double electromagnetic valves are used for controlling a compression stroke and a recovery stroke respectively; the negative stiffness assembly comprises an annular inner permanent magnet fixed to the piston rod and an annular outer permanent magnet fixed to the middle cylinder; the electronic control unit is used for receiving a detection signal of a sensor arranged on the vehicle in real time and calculating the optimal control force under the current working condition based on the detection signal; negative stiffness force is calculated according to the relative position of the permanent magnet, compensation damping force is calculated based on the optimal control force and the negative stiffness force, and target damping force is achieved through adjustment by controlling the opening degree of an electromagnetic valve. The comfort level of the suspension system is improved, and the driving experience feeling of the vehicle is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a suspension system of a vehicle, in particular to a CDC shock absorber with a negative stiffness component, a suspension system and a vehicle. BACKGROUND

[0002] Continuous Damping Control (CDC) shock absorber is a damping system based on electromagnetic damping control technology. It can sense the motion state of the vehicle and the road condition in real time through sensors, and then adjust the damping force of the shock absorber through the electromagnetic damping controller to adapt to different driving conditions and road conditions. This system can improve the handling, comfort and stability of the vehicle, so that the driver can experience a more stable and comfortable driving experience during driving. In order to improve the performance of semi-active CDC suspension, a lot of efforts have been made. For example, CDC shock absorber equipped with double electromagnetic valves can improve damping under constrained conditions, achieve faster response and lower magnetic resistance, thereby improving damping performance. In addition to structural design, developing effective control algorithms is essential to optimize suspension performance. Skyhook control, sliding mode control and other methods have been proposed or used to improve the damping performance of semi-active CDC shock absorbers in vehicle suspensions.

[0003] Despite the above improvements, the vibration damping performance of semi-active suspension systems is still lower than that of active suspension systems. In contrast, active suspension systems can generate active control forces to suppress vibrations. The lack of this inherent feature in semi-active suspension systems has prompted researchers to explore alternative mechanisms that can provide comparable performance.

[0004] Under appropriate control, active suspensions exhibit significant negative stiffness characteristics, which are very beneficial to improving vibration damping performance. The discovery of negative stiffness characteristics has prompted researchers to explore their potential applications in depth, especially in the field of vibration suppression. The introduction of negative stiffness can effectively attenuate the dynamic stiffness of the system to achieve low transmissibility, making it a useful and necessary technique to improve vibration damping performance. SUMMARY

[0005] Therefore, the embodiments of the present application expect to provide a CDC shock absorber with a negative stiffness component, a suspension system and a vehicle to at least solve the above technical problems.

[0006] To achieve the above object, the technical scheme of the present application is as follows:

[0007] According to an aspect of the embodiments of the present application, a CDC shock absorber with a negative stiffness component is provided, comprising:

[0008] The double-cylinder shock absorber body comprises an outer cylinder and an inner cylinder filled with shock absorber oil;

[0009] A piston assembly comprising a piston disposed in an inner cylinder and a piston rod penetrating through an outer cylinder;

[0010] A solenoid valve system comprising a double solenoid valve controlling compression stroke and recovery stroke respectively and corresponding bypass oil paths;

[0011] A negative stiffness assembly comprising a circular ring-shaped inner permanent magnet fixed to the piston rod and a ring-shaped outer permanent magnet fixed to the intermediate cylinder;

[0012] An electronic control unit receiving detection signals of sensors disposed on the vehicle in real time, calculating optimal control force under current working condition based on the detection signals, calculating negative stiffness force according to relative position of the permanent magnets, calculating compensation damping force based on the optimal control force and the negative stiffness force, adjusting target damping force by controlling opening degree of the solenoid valve;

[0013] Wherein, axial height of the inner permanent magnet and the outer permanent magnet is equal and they are arranged with same polarity, and radial gap is 4-8mm.

[0014] In the above scheme, the negative stiffness force of the negative stiffness assembly satisfies the following relationship:

[0015]

[0016] Wherein, k is magnetic circuit coefficient, B r1 and B r2 are residual magnetism of the inner and outer permanent magnets respectively, A is effective action area, d is radial gap, and x is relative displacement.

[0017] In the above scheme, the inner and outer permanent magnets adopt N52 grade neodymium iron boron material, axial height is 18-22mm, and radial gap is 5-7mm.

[0018] In the above scheme, the solenoid valve system comprises:

[0019] A proportional solenoid valve disposed on the piston valve, which controls main oil path flow, and flow control of the valve port is as follows:

[0020]

[0021] Q is flow (L / min), C d is quantity coefficient, and A(x) is valve port flow area (mm 2 ), which is related to valve core displacement x as follows:

[0022]

[0023] Wherein, D is valve seat diameter, θ is valve core taper angle, ΔP is valve port pressure difference (MPa), and ρ is oil density;

[0024] A high-speed on-off valve disposed on the independent bypass oil path;

[0025] Pressure compensation valve provided at the bottom valve.

[0026] In the above scheme, the bypass oil path is provided with an array of throttle holes in parallel, each throttle hole has a diameter arranged in a binary sequence.

[0027] In the above scheme, the electronic control unit determines based on the following manner:

[0028] Determine the body motion equation:

[0029]

[0030] m is the body mass (kg), is the body vertical acceleration (m / s 2 ), is the body vertical speed (m / s), is the wheel vertical speed (m / s), k is the suspension spring stiffness (N / m), C sky is the Skyhook damping coefficient (N·s / m), suspension dynamic travel; represents the body upward movement, represents the wheel upward movement, z b -z w represents the suspension dynamic travel, represents the suspension relative speed;

[0031] The Skyhook damping force is determined by the following formula:

[0032]

[0033] C min () represents the minimum value of the shock absorber damping coefficient (N·s / m), C min is the minimum damping coefficient of the shock absorber;

[0034] Adjust the parameters to adapt to different working conditions,

[0035]

[0036] C base is the basic damping coefficient (N·s / m), α is the adaptive gain coefficient, is the preset maximum body speed (m / s);

[0037] When the integrated negative stiffness component is integrated, the total control force is:

[0038] F total = F skyhook +F negative_stiffness

[0039] Wherein, the negative stiffness force calculation method is as follows:

[0040] F negative_stiffness = K ns · (z b -z w )

[0041] K ns is a negative stiffness coefficient, determined by the permanent magnet parameters.

[0042] In the above scheme, the electronic control unit calculates the compensation current according to the relative displacement of the magnet, as follows:

[0043]

[0044] F target is the target damping force, K v is the electromagnetic valve force-current gain, β is the direction asymmetry coefficient, v rel is the piston relative speed.

[0045] In the above scheme, the electronic control unit coordinates the vehicle body pitch, roll and vertical vibration by the following method:

[0046] Determine the vertical force of the vehicle:

[0047]

[0048] F z，i is the vertical target damping force of the i-th wheel, fl is the left front wheel, fr is the right front wheel, rl is the left rear wheel, and rr is the right rear wheel; c sky，i is the Skyhook damping coefficient of the i-th wheel, is the vertical speed of the vehicle body at the i-th wheel;

[0049] Pitch moment compensation is performed by the following method:

[0050]

[0051] F pitch is the pitch compensation force, k p is the pitch stiffness coefficient, θ is the vehicle body pitch angle, is the pitch angular velocity, c p is the pitch damping coefficient;

[0052] F roll = k r · φ + c r · φ

[0053] F roll is the roll compensation force, k r is the roll stiffness coefficient, Φ is the vehicle body roll angle, c ris a roll damping coefficient, is a roll angle velocity of the vehicle body;

[0054]

[0055] F i is the final target force of the ith wheel, w1 is a vertical comfort weight, w2 is a pitch suppression weight, and w3 is a roll suppression weight.

[0056] According to a second aspect of the present application, a vehicle suspension system is provided, comprising four CDC dampers as described above, and the electronic control units of each damper are interconnected through a CAN bus

[0057] According to a third aspect of the present application, a vehicle is provided, comprising the vehicle suspension system of any one of the above.

[0058] The CDC damper with negative stiffness assembly, the suspension system and the vehicle provided by the present application reduce the RMS value of the vertical acceleration of the vehicle body by 5-10% through the synergistic effect of the integrated negative stiffness assembly, multi-target optimization control and CDC solenoid valve, reduce the natural frequency of the system from 1.5 Hz to 0.8-1.0 Hz, reduce the dynamic pitch angle by 55-65%, reduce the roll angle during high-speed cornering by 10-15%, reduce the average working current from 1.8 A to 1.6 A, and the negative stiffness provides 30-50% of the required force, thereby reducing the current consumption in unnecessary working conditions. Through the active cancellation of the force applied to each direction of the suspension, the comfort of the suspension system is improved, and the driving experience of the vehicle is improved. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 is a flow implementation schematic diagram of the vehicle brake force control method in the present application;

[0060] Figure 2 is a structural composition schematic diagram of the vehicle brake force control device in the present application;

[0061] Figure 3 is an optimization schematic diagram of the negative stiffness assembly based on the magnetic charge model in the present application. DETAILED DESCRIPTION

[0062] The technical solutions of the present application are further described in detail below in combination with the accompanying drawings and specific embodiments.

[0063] In the specific embodiments, each specific technical feature in each of the various embodiments described in the specific embodiments can be combined in various combinations, for example, different specific technical features can form different embodiments through combination. In order to avoid unnecessary repetition, various possible combinations of each specific technical feature in the present application are not described again.

[0064] It should be noted that the terms "first", "second", "third" in the embodiments of the present application are only to distinguish similar objects, and do not represent a specific order of the objects. It can be understood that the "first", "second", "third" can be interchanged in a specific order or sequence as appropriate. It should be understood that the objects distinguished by "first", "second", "third" can be interchanged as appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0065] Figure 1 The structure diagram of the shock absorber of the embodiments of the present application is shown as Figure 1 The shock absorber of the embodiments of the present application comprises:

[0066] The cylinder 6 is usually a double-cylinder or single-cylinder structure, and is filled with shock absorber oil inside; the piston reciprocates in the cylinder 6, and an oil flow channel is usually provided on the piston. The piston rod 1 connects the piston and the vehicle body or the suspension component. The dustproof device 2 is arranged on one side of the cylinder 6, the guide and oil seal 3 is arranged on the other side of the dustproof device 2, the inner cylinder 4 is arranged in the cylinder, the middle cylinder 5 is arranged in a symmetrical manner with respect to the axis of the cylinder, the core control element is the electromagnetic valve 7, the lug 8 is arranged at the other end of the cylinder 6, the bottom valve 9 is arranged at the other opening end of the cylinder 6, the piston valve 10 is arranged on the flow valve support 11, and the limiting block 12 is arranged on the connecting shaft of the piston rod 1, which is close to the lug 8 side, so as to limit the piston rod.

[0067] The shock absorber of the embodiments of the present application further comprises: a damping valve system (Valve System): a conventional shock absorber controls the oil flow resistance by a valve piece on the piston and a bottom valve to generate a damping force. The CDC shock absorber is improved on this basis.

[0068] The electromagnetic valve 7 is usually integrated inside the shock absorber (commonly used in high-end CDC) or mounted outside (connected with the shock absorber body through an oil pipe).

[0069] The electromagnetic valve 7 can accurately control the flow of oil flowing through the internal channel of the shock absorber. When the current of the electromagnetic valve 7 changes, the opening of the valve changes, thereby changing the resistance of the oil flow, and further adjusting the size of the damping force. Commonly used are proportional valves or step motor controlled valves, which can realize fine adjustment of the oil flow. The current mainstream CDC shock absorber design tends to adopt a double electromagnetic valve configuration, which respectively controls the damping of the compression and recovery strokes, to realize more independent and more accurate adjustment.

[0070] The oil passage design inside the CDC damper is more complex than the traditional damper. In addition to the conventional piston valve and bottom valve 9, the CDC damper of the embodiment of the application further increases the bypass oil passage or additional throttle hole controlled by the electromagnetic valve, and the continuous adjustable damping force is realized by controlling the on-off or throttle size of the bypass oil passage. The CDC damper is a core actuator of a typical semi-active suspension system. Its working principle is a closed-loop control process involving real-time cooperation between sensors, electronic control units (ECU) and electromagnetic valve dampers.

[0071] Specifically, the CDC damper of the embodiment of the application comprises:

[0072] A double-cylinder damper body containing an outer cylinder and an inner cylinder filled with damper oil;

[0073] A piston assembly containing a piston arranged in the inner cylinder and a piston rod penetrating the outer cylinder;

[0074] An electromagnetic valve system containing double electromagnetic valves respectively controlling the compression stroke and the recovery stroke and corresponding bypass oil passages; the bypass oil passage is provided with a parallel throttle hole array, and each throttle hole has a diameter arranged in a binary sequence.

[0075] The electromagnetic valve system comprises a proportional electromagnetic valve arranged on the piston valve, which controls the main oil passage flow, and the flow control of the valve port is as follows:

[0076]

[0077] Q is the flow (L / min), C d is the quantity coefficient, A(x) is the valve port flow area (mm 2 ), which is related to the displacement x of the valve core as follows:

[0078]

[0079] Where D is the valve seat diameter, θ is the valve core cone angle, ΔP is the valve port pressure difference (MPa), and ρ is the oil density;

[0080] The CDC damper of the embodiment of the application further comprises:

[0081] A high-speed on-off valve arranged on the independent bypass oil passage;

[0082] A pressure compensation valve arranged at the bottom valve.

[0083] A negative stiffness assembly containing a circular ring-shaped inner permanent magnet fixed to the piston rod and a ring-shaped outer permanent magnet fixed to the intermediate cylinder; the inner and outer permanent magnets are made of N52 grade neodymium iron boron material, the axial height is 18-22 mm, and the radial gap is 5-7 mm.

[0084] The electronic control unit receives the detection signals of the sensors arranged on the vehicle in real time, calculates the optimal control force under the current working condition based on the detection signals, calculates the negative stiffness force according to the relative position of the permanent magnet, calculates the compensation damping force based on the optimal control force and the negative stiffness force, and adjusts the opening degree of the electromagnetic valve to realize the target damping force; wherein the axial height of the inner permanent magnet and the outer permanent magnet is equal and the inner permanent magnet and the outer permanent magnet are arranged in the same polarity, and the radial gap is 4-8mm.

[0085] The various sensors installed on the vehicle of the embodiment of the application are used to collect data in real time, including:

[0086] Vehicle body vertical acceleration sensor: detects the up-and-down vibration (bump, heave) of the vehicle body.

[0087] Wheel vertical acceleration sensor: detects the bouncing of the wheel.

[0088] Wheel speed sensor: provides vehicle speed information.

[0089] Lateral / longitudinal acceleration sensor: detects the roll and pitch of the vehicle, and reflects the steering, acceleration, and braking operations of the driver.

[0090] Steering angle sensor, brake pressure sensor, etc.: further provides the driver's intention information.

[0091] All sensor data are transmitted to a dedicated CDC control unit (ECU).

[0092] The ECU has a complex control algorithm (such as Skyhook control, H-infinity control, fuzzy control, etc.) preset inside. These algorithms will comprehensively judge the current road conditions (flat, bumpy, potholed), the driver's intention (acceleration, braking, turning, high-speed cruising), and the dynamic state of the vehicle (vehicle body pitch, roll, vibration frequency and amplitude) according to the real-time collected data.

[0093] The core task of the ECU is to calculate the optimal damping force required by each wheel at the moment.

[0094] Damping force adjustment: the ECU sends the calculated instructions to the electromagnetic valve inside or outside each CDC shock absorber. The electromagnetic valve quickly and accurately adjusts the opening degree of the valve according to the received current signal (usually a PWM signal, pulse width modulation). When hard damping is needed (such as emergency braking, high-speed cornering, and supporting the vehicle body), the ECU will instruct the electromagnetic valve to reduce the opening degree to limit the flow of oil, thereby increasing the resistance. When soft damping is needed (such as driving on flat roads and pursuing comfort), the ECU will instruct the electromagnetic valve to increase the opening degree to allow the oil to flow more easily, thereby reducing the resistance.

[0095] Specifically, the electronic control unit determines the control opening degree of the electromagnetic valve based on the following manner:

[0096] The body motion equation is determined as follows:

[0097]

[0098] m is the body mass (kg), is the body vertical acceleration (m / s 2 ), is the body vertical velocity (m / s), is the wheel vertical velocity (m / s), k is the suspension spring stiffness (N / m), C sky is the Skyhook damping coefficient (N·s / m), suspension dynamic travel; represents the body upward motion, represents the wheel upward motion, z b -z w represents the suspension dynamic travel, represents the suspension relative velocity;

[0099] The Skyhook damping force is determined by the following formula:

[0100]

[0101] C min () represents that the shock absorber damping coefficient (N·s / m) takes the minimum value, C min is the minimum damping coefficient of the shock absorber;

[0102] The parameters are adjusted to adapt to different working conditions,

[0103]

[0104] C base is the basic damping coefficient (N·s / m), and α is the adaptive gain coefficient, is the preset maximum body speed (m / s);

[0105] When the integrated negative stiffness component is integrated, the total control force is:

[0106] F total = F skyhook +F negatiive_stiffness

[0107] Wherein, the negative stiffness force is calculated as follows:

[0108] F negative_stiffness = K ns ·(z b -z w )

[0109] Kns is the negative stiffness coefficient, which is determined by the permanent magnet parameters.

[0110] The compensation current is calculated based on the relative displacement of the magnets as follows;

[0111]

[0112] F target is the target damping force, K v is the solenoid valve force-current gain, β is the direction asymmetry coefficient, v rel is the relative speed of the piston.

[0113] The electronic control unit coordinates the vehicle body's pitch, roll, and vertical vibrations in the following ways:

[0114] Determine the vertical force on the vehicle:

[0115]

[0116] F z，i is the vertical target damping force of the i-th wheel, fl is the left front wheel, fr is the right front wheel, rl is the left rear wheel, and rr is the right rear wheel; c sky,i is the Skyhook damping coefficient of round i, is the vertical velocity of the vehicle body at the i-th wheel;

[0117] Pitching moment compensation is performed in the following way:

[0118]

[0119] F pitch is the pitch compensation force, k p is the pitch stiffness coefficient, θ is the vehicle body pitch angle, is the pitch angular velocity, c p is the pitch damping coefficient;

[0120] F roll =k r ·φ+c r ·φ

[0121] F roll is the roll compensation force, kr is the roll stiffness coefficient, Φ is the body roll angle, c r is the roll damping coefficient, is the body roll angular velocity;

[0122]

[0123] F i is the final target force of the i-th wheel, w1 is the vertical comfort weight, w2 is the pitch suppression weight, and w3 is the roll suppression weight.

[0124] The above adjustment process is continuous and real-time, and the response and adjustment can be completed within a few milliseconds, achieving "stepless" adjustment of the damping force.

[0125] After the damping force of the shock absorber is adjusted, the dynamic response of the vehicle will change, and these changes will be detected by the sensor to form new data feedback to the ECU, and the cycle is repeated, forming a dynamic closed-loop control system.

[0126] In the embodiment of the application, the electronic control unit can be an MCU, an ECU, etc., which is arranged in the vehicle to realize overall control of the vehicle. The electronic control unit can receive the detection signals of the sensors arranged in the vehicle in real time, calculate the optimal control force under the current working condition based on the detection signals, calculate the compensation damping force based on the optimal control force and the negative stiffness force calculated according to the relative position of the permanent magnet, and adjust the opening degree of the electromagnetic valve to realize the target damping force. Wherein, the axial height of the inner permanent magnet and the outer permanent magnet is equal and the same pole is arranged opposite, and the radial gap is 4-8mm. As an example, the radial gap can be 5mm, 5.2mm, 5.4mm, 5.5mm, 5.8mm, 6mm, 6.2mm, 6.5mm, 6.8mm, 7mm, or 7.5mm, etc.

[0127] Ordinary CDC damper and compact negative stiffness assembly. The traditional CDC variable damping damper is mainly composed of a traditional shock absorber and an intermediate cylinder and a CDC electromagnetic valve. The magnetic negative stiffness assembly is added to the traditional CDC shock absorber, which is a fine feature involving the integration of two different groups of permanent magnets. This structural complexity helps to improve the damping of the damper in various working conditions.

[0128] The negative stiffness force of the negative stiffness assembly of the embodiment of the application satisfies the following relationship:

[0129]

[0130] Wherein, k is the magnetic circuit coefficient, B r1 , B r2 are the residual magnetism of the inner and outer permanent magnets respectively, A is the effective action area, d is the radial gap, and x is the relative displacement amount.

[0131] Figure 2 is a structural schematic diagram of the CDC shock absorber of the embodiment of the application, as Figure 2The inner permanent magnet is a circular ring permanent magnet fixed on the stainless steel piston rod. The inner permanent magnet can be changed in size by replacing the original metal limit block on the CDC shock absorber with a magnetic material, and the stainless steel piston rod is connected to the limit block to ensure that the relative movement of the piston cylinder can drive the inner magnet to move. The limit block is made of permanent magnetic material in the embodiment of the application, and no new components need to be added to the piston rod, i.e. no additional magnet components are needed. The outer permanent magnet is a ring-shaped permanent magnet, which can be inserted by adding a ring-shaped magnetic body in the middle cylinder of the shock absorber. This design utilizes the guiding effect of the guide and the stainless steel piston rod to give this compact negative stiffness magneto-rheological damper a certain ability to resist lateral force. The relative movement between the piston rod and the middle cylinder allows the relative movement between the inner and outer permanent magnets. The height of the two permanent magnets is 20 mm, and the same height ensures the maximum negative stiffness force under the same size. The center of the outer circular ring permanent magnet must coincide with the center of the inner circular ring permanent magnet to generate the maximum negative stiffness. The radial gap between the outer circular ring permanent magnet and the inner circular ring permanent magnet is 6 mm. Figure 2 The overall assembly diagram is also shown. The inner circular ring permanent magnet is connected to the outer cylinder through the stainless steel piston rod, and relative movement is achieved when the connecting component moves. The magnetic pole directions of the inner circular ring permanent magnet and the outer circular ring permanent magnet are the same. They are axially magnetized NdFeB permanent magnets with a grade of N52.

[0132] The compact negative stiffness component is responsible for generating negative stiffness, in other words, driving force, while the ordinary CDC damper provides adaptive compensation damping force according to different requirements. The inner cylindrical permanent magnet is fixed relative to the piston rod, while the outer cylindrical magnet can move with the damper cylinder. Negative stiffness is generated throughout the damper movement, and its absolute value reaches a maximum when the centers of the two groups of magnets coincide. When the centers of the two groups of magnets deviate, the value begins to decrease until the negative stiffness disappears due to the disappearance of the interaction. During this process, the negative stiffness will offset part of the positive stiffness of the external spring, thereby reducing the stiffness of the entire suspension system. However, this phenomenon only exists within the interaction distance between the two groups of magnets, and is therefore referred to as negative stiffness related to stroke. Since the stiffness of the external spring is designed to be much larger than the negative stiffness, the total suspension stiffness remains positive. By controlling the damping parameters, the ordinary magneto-rheological damper can meet different working conditions. It will generate a damping force to compensate for the required control force, thereby improving the effectiveness of vibration control and ensuring the stability of the control system. In summary, the negative stiffness element generates driving force, while the CDC damper adjusts the control force according to different requirements, thereby further improving the damping performance and ensuring the stability of the system.

[0133] Figure 3 The schematic diagram for optimizing the negative stiffness component based on the magnetic charge model of the present application is as follows: Figure 3As shown, to clarify how negative stiffness provides superior vibration attenuation performance, the present embodiment introduces the concept of four quadrants for explanation. Under appropriate control algorithm, the hysteresis loop of the optimal control force (ROCF) required by the active suspension exhibits significant negative stiffness characteristics. The core condition for semi-active suspension performance close to that of active suspension is to generate ROCF with negative stiffness component. It is this negative stiffness characteristic that makes the active suspension have more superior vibration attenuation performance than the semi-active suspension. From the energy point of view, this means that the optimal control force of the active suspension can dissipate and generate energy under different conditions. The negative stiffness component designed in the present embodiment is integrated into the CDC damper. The CDC damper and the compact negative stiffness component are the key components of the new type of magneto-rheological semi-active suspension. In order to optimize the parameters of the negative stiffness component and the piston, a magnetic force model is established based on the Coulomb model to optimize the size of the negative stiffness component.

[0134] A magnetic charge model is created, which is the most basic conceptual model that attributes the magnetic force of a magnet to the interaction between the "magnetic charges" on the poles. Although the magnetic charge does not really exist in physics, it is very useful in calculating the magnetic force. Basic magnetic charge force formula (analog of Coulomb's law in magnetic field):

[0135] ·Basic magnetic charge force formula (analog of Coulomb's law in magnetic field):

[0136]

[0137] Where:

[0138] ·F is force (N)

[0139] ·μ0 is the vacuum permeability (4π×10 -7 H / m)

[0140] ·q m1 ,q m2 is the magnetic charge size (A·m)

[0141] ·r is the distance between the two magnetic charges (m)

[0142] The present embodiment also describes a vehicle suspension system comprising four CDC dampers of the foregoing embodiments, and the electronic control units of each damper are interconnected through a CAN bus.

[0143] The present application also provides a vehicle comprising the vehicle suspension system provided by the above embodiment.

[0144] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. In addition, the disclosed features in several method or device embodiments provided in the present application can be combined arbitrarily without conflict, to obtain new method embodiments or device embodiments.

[0145] The above descriptions are merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A CDC shock absorber with a negative stiffness component, characterized in that: The shock absorber comprises: The double-tube shock absorber body consists of an outer tube and an inner tube filled with shock absorber oil; A piston assembly comprising a piston disposed in the inner cylinder and a piston rod passing through the outer cylinder; The solenoid valve system includes dual solenoid valves that control the compression stroke and the recovery stroke respectively, and corresponding bypass oil circuits; A negative stiffness component comprises an inner annular permanent magnet fixed to the piston rod and an outer annular permanent magnet fixed to the intermediate cylinder; The electronic control unit receives detection signals from sensors installed on the vehicle in real time and calculates the optimal control force under the current working conditions based on the detection signals. It calculates the negative stiffness force based on the relative position of the permanent magnets and calculates the compensating damping force based on the optimal control force and the negative stiffness force. It adjusts the target damping force by controlling the opening of the solenoid valve. The inner permanent magnet and the outer permanent magnet have the same axial height and are arranged opposite to each other with the same poles, and the radial gap is 4-8 mm.

2. The CDC shock absorber according to claim 1, characterized in that: The negative stiffness force of the negative stiffness component satisfies the following relationship: Among them, k is the magnetic circuit coefficient, B r1 、B r2 are the remanent magnetism of the inner and outer permanent magnets respectively, A is the effective area, d is the radial gap, and x is the relative displacement.

3. The CDC shock absorber according to claim 1, characterized in that: The inner and outer permanent magnets are made of N52 grade neodymium iron boron material, with an axial height of 18-22 mm and a radial gap of 5-7 mm.

4. The CDC shock absorber according to claim 1, characterized in that: The solenoid valve system comprises: The proportional solenoid valve installed on the piston valve controls the flow of the main oil circuit. The flow control of the valve port is as follows: Q is the flow rate (L / min), C d is the volume coefficient, A(x) is the valve port flow area (mm 2 ), which is related to the valve core displacement x as follows: Where D is the valve seat diameter, θ is the valve core cone angle, ΔP is the valve port pressure difference (MPa), and ρ is the oil density; A high-speed on-off valve provided on an independent bypass oil line; A pressure compensating valve located at the bottom valve.

5. The CDC shock absorber according to claim 4, characterized in that: The bypass oil circuit is provided with a parallel throttle hole array, and the diameters of the throttle holes are arranged in a binary sequence.

6. The CDC shock absorber according to claim 1, characterized in that: The electronic control unit is determined based on the following method: Determine the equation of motion of the vehicle body: m is the vehicle mass (kg), is the vertical acceleration of the vehicle body (m / s 2 ), is the vertical speed of the vehicle body (m / s), is the vertical speed of the wheel (m / s), k is the suspension spring stiffness (N / m), C sky is the Skyhook damping coefficient (N·s / m), suspension dynamic travel; Indicates that the vehicle body moves upward. Indicates that the wheel moves upward, z b -z w Indicates the suspension travel. represents the relative speed of the suspension; Skyhook damping force is determined by the following formula: C min () is the minimum value of the shock absorber damping coefficient (N·s / m), C min is the minimum damping coefficient of the shock absorber; Adjust the parameters to suit different working conditions. C base is the basic damping coefficient (N·s / m), α is the adaptive gain coefficient, is the preset maximum vehicle speed (m / s); When the negative stiffness components are integrated, the total control force is: F total =F skyhook +F negative_stiffness The negative stiffness force is calculated as follows: F negative_stiffness =K ns ·(With b -With w ) K ns is the negative stiffness coefficient, which is determined by the permanent magnet parameters.

7. The CDC shock absorber according to claim 1, characterized in that: The electronic control unit calculates the compensation current according to the relative displacement of the magnets as follows; F target is the target damping force, K v is the solenoid valve force-current gain, β is the direction asymmetry coefficient, v rel is the relative speed of the piston.

8. The CDC shock absorber according to claim 1, characterized in that: The electronic control unit coordinates the vehicle body pitch, roll and vertical vibration in the following ways: Determine the vertical force on the vehicle: F z，i is the vertical target damping force of the i-th wheel, fl is the left front wheel, fr is the right front wheel, rl is the left rear wheel, and rr is the right rear wheel; c sky,i is the Skyhook damping coefficient of round i, is the vertical velocity of the vehicle body at the i-th wheel; Pitching moment compensation is performed in the following way: F pitch is the pitch compensation force, k p is the pitch stiffness coefficient, θ is the vehicle body pitch angle, is the pitch angular velocity, c p is the pitch damping coefficient; F roll is the roll compensation force, k r is the roll stiffness coefficient, Φ is the body roll angle, c r is the roll damping coefficient, is the body roll angular velocity; F i is the final target force of the i-th wheel, w1 is the vertical comfort weight, w2 is the pitch suppression weight, and w3 is the roll suppression weight.

9. A vehicle suspension system, characterized in that: The invention comprises four CDC shock absorbers according to any one of claims 1 to 8, and the electronic control units of the shock absorbers are interconnected via a CAN bus.

10. A vehicle, characterized in that: A vehicle suspension system comprising the vehicle suspension system of claim 9.

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