CN108547910A - A kind of damp can be changed automobile hydraulic shock-damping device and its control method - Google Patents

Abstract

The invention discloses a damping variable automobile hydraulic shock absorber, which comprises: a working cylinder, which is provided with a flowable damping fluid inside; a piston rod, which is arranged in the working cylinder and can move axially along the working cylinder; a piston, It is arranged on the piston rod, and a damping channel is set between the outer peripheral surface of the piston and the inner wall of the working cylinder for the circulation of the damping liquid; the groove is arranged along the circumference of the middle part of the piston, and the An exciting coil is wound around the bottom of the groove; a spring is sheathed outside the working cylinder. During the driving process of the vehicle, the damping of the shock absorber is variable, which improves driving comfort and stability. The present invention also provides a control method for a hydraulic shock absorber with variable damping. During the running of the vehicle, the damping of the damper is controlled according to the compression state of the spring of the shock absorber, so as to improve driving comfort and stability. Adjust the balance coefficient according to the driving state of the car and the road surface conditions, making the car driving more stable and comfortable.

Description

A variable damping automobile hydraulic shock absorber and its control method

technical field

The invention relates to the technical field of automobile shock absorption, and more specifically, the invention relates to an automobile hydraulic shock absorber with variable damping and a control method thereof.

Background technique

The shock absorber is the main component that generates damping force, and its function is to quickly attenuate the vibration of the car, improve the ride comfort of the car, and enhance the adhesion between the wheel and the ground. In addition, the shock absorber can reduce the dynamic load of the body part and prolong the service life of the car.

The function of the elastic element in the automobile suspension system is to buffer the vibration caused by the uneven road surface when the vehicle is running, reduce the acceleration of the vehicle body and reduce the dynamic load and dynamic stress of the relevant parts. If there were only elastic elements, the car would continue to vibrate after one impact. But the car is running on the continuous uneven road, and the continuous impact caused by the continuous unevenness will inevitably increase the vibration of the car, and even resonate, which will increase the dynamic load of the car body. Therefore, the damping in the suspension must match the characteristics of the elastic elements to avoid the repeated movement of the spring, suppress the continuous jumping of the spring, improve driving comfort and stability, and increase the service life of the parts.

The ordinary damper used in traditional cars has a constant damping coefficient and cannot be changed with the quality of the road the car is driving on and the load of the car, making the car appear "softer" when the load is too heavy, and "harder" when the load is too small; Or the vehicle appears "softer" when the vibration is large, and "harder" when the vibration is small, which reduces the service life of the parts and reduces the driving comfort and stability.

Contents of the invention

One purpose of the present invention is to design and develop a variable damping automobile hydraulic shock absorber. During the driving process of the vehicle, the damping of the shock absorber can be changed to improve driving comfort and stability.

Another object of the present invention is to design and develop a control method for a variable damping automotive hydraulic shock absorber. During the running of the vehicle, the damping of the damper is controlled according to the spring compression state of the shock absorber, so as to improve driving comfort and smoothness.

The present invention can also regulate the balance coefficient according to the running state of the vehicle and the road conditions during the driving process of the vehicle, so that the driving of the vehicle is more stable and comfortable.

The technical scheme provided by the invention is:

A damping variable automotive hydraulic shock absorber, comprising:

A working cylinder is provided with a flowable damping fluid inside;

a piston rod, which is arranged in the working cylinder and can move axially along the working cylinder;

a piston, which is arranged on the piston rod, and a damping channel is arranged between the outer peripheral surface of the piston and the inner wall surface of the working cylinder for the circulation of the damping liquid;

a groove, which is arranged circumferentially along the middle part of the piston, and an excitation coil is wound around the bottom of the groove in the circumferential direction, and the excitation coil has 20 to 50 turns;

The spring is sleeved on the outside of the working cylinder.

Preferably, it also includes:

a first connecting rod, one end of which is connected to the axle, and the other end is connected to the bottom of the working cylinder;

The second connecting rod is connected to the vehicle suspension at one end and to the piston rod at the other end.

Preferably, it also includes:

A speed sensor, which is arranged on the outer wall surface of the working cylinder, is used to detect the driving speed of the vehicle;

a weight sensor, which is arranged on the axle and is used to detect the weight of the vehicle;

Infrared sensors, which are arranged at both ends of the spring, are used to detect the length of the spring;

A vibration sensor, which is arranged on the outer wall surface of the working cylinder, is used to detect the vibration amplitude of the automobile;

The controller is connected with the speed sensor, weight sensor, infrared sensor, vibration sensor and excitation coil for receiving the detection data of the speed sensor, weight sensor, infrared sensor and vibration sensor and controlling the operation of the excitation coil.

Correspondingly, the present invention also provides a control method of a variable damping automotive hydraulic shock absorber, including:

To collect the weight of the vehicle and the real-time length of the spring, the controller controls the magnitude of the alternating current passing through the excitation coil as follows:

Among them, I is the size of the alternating current passing through the excitation coil, r is the radius of the excitation coil, π is the circumference ratio, k is the stiffness coefficient of the spring, D ₀ is the inner diameter of the working cylinder, d is the width of the damping channel, η ₀ is the viscosity of the damping fluid when there is no external magnetic field, y is the distance from a point in the damping fluid to the central axis of the working cylinder, ξ is the balance coefficient, x ₀ is the initial length of the spring, x is the real-time length of the spring, and M is the weight of the vehicle , g is the acceleration due to gravity.

Preferably, the frequency of the alternating current is 60Hz.

Preferably, when the car is running, the balance coefficient is regulated based on the BP neural network, including the following steps:

Step 1: The magnetic permeability μ of the damping fluid is known, and according to the sampling period, the vehicle weight M, the difference between the initial length of the spring and the real-time length Δx, the vehicle speed v and the amplitude A of the vehicle are measured through the sensor;

Step 2: Normalize the above parameters in turn to determine the input layer vector x={x ₁ ,x ₂ ,x ₃ ,x ₄ ,x ₅ } of the three-layer BP neural network; where x ₁ is the vehicle weight coefficient, x ₂ is the spring length difference coefficient, x ₃ is the vehicle speed coefficient, x ₄ is the amplitude coefficient of the vehicle, and x ₅ is the magnetic permeability coefficient of the damping fluid;

Step 3: The input layer vector is mapped to the middle layer, the middle layer vector y={y ₁ , y ₂ ,...,y _m }; m is the number of middle layer nodes;

Step 4: Get the output layer vector z={z ₁ }; where, z ₁ is the adjustment coefficient of the balance coefficient, so that

ξ _i+1 = z ₁ ⁱ ξ _max ,

Among them, z ₁ ⁱ is the output layer vector parameter of the ith sampling period, and ξ _max is the set maximum balance coefficient of the shock absorber.

Preferably, the number m of nodes in the middle layer satisfies: Among them, n is the number of nodes in the input layer, and p is the number of nodes in the output layer.

Preferably, in the step 2, the normalized formula of vehicle weight M, spring length difference Δx, vehicle speed v and vehicle amplitude A is:

Among them, x _j is the parameter in the input layer vector, X _j is the measurement parameter M, Δx, v, A, j=1, 2, 3, 4; X _jmax and X _jmin are the maximum values of the corresponding measurement parameters and min;

The normalization formula of the magnetic permeability μ of the damping fluid is:

Among them, x ₅ is the parameter in the input layer vector, X ₅ is the magnetic permeability of the damping fluid used by the shock absorber, X _5min is the minimum magnetic permeability of the damping fluid that the shock absorber can use, and X _5max is the shock absorber The maximum permeability of the damping fluid that can be used.

Preferably, in said step 1, under the initial operating state, the balance coefficient satisfies the empirical value:

ξ ₀ = 0.8ξ _max ;

Among them, ξ ₀ is the initial balance coefficient of the shock absorber; ξ _max is the set maximum balance coefficient of the shock absorber.

Preferably, the set maximum balance coefficient ξ _max =1 of the shock absorber.

The beneficial effects described in the present invention are:

(1) In the variable damping automotive hydraulic shock absorber of the present invention, the damping of the shock absorber is variable during the running of the vehicle, which improves driving comfort and stability, and also improves the service life of parts.

(2) the control method of damping variable automobile hydraulic shock absorber of the present invention, according to shock absorber spring compression state, controls the size of the electric current of the excitation coil in damper according to empirical formula; The magnitude of the current of the excitation coil is controlled so that the magnitude of the generated magnetic field is controllable. The viscosity of the damping fluid (magneto-rheological fluid) in the shock absorber changes according to the magnetic field, and the resulting damping coefficient is also different. Therefore, according to The compression state of the spring can control the damping of the shock absorber, improving driving comfort and stability. The present invention can also regulate the balance coefficient according to the running state of the vehicle and the road conditions during the driving process of the vehicle, so that the driving of the vehicle is more stable and comfortable.

Description of drawings

Fig. 1 is a schematic diagram of the installation of the damping variable automobile hydraulic shock absorber of the present invention.

Fig. 2 is a structural schematic diagram of the damping variable automobile hydraulic shock absorber of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings, so that those skilled in the art can implement it with reference to the description.

As shown in Figures 1 and 2, the present invention provides a variable damping automobile suspension shock absorber, including: a working cylinder 110, which is provided with a flowable damping fluid 120 inside; a piston rod 130, which is arranged on the working cylinder The inner 110 can move axially along the working cylinder 110; the piston 140 is arranged on the piston rod 130, and a damping channel 150 is arranged between the outer peripheral surface of the piston 140 and the inner wall surface of the working cylinder 110 for use In the circulation of the damping liquid 120; the groove 141 is arranged along the circumferential direction of the middle part of the piston 140, and the excitation coil 142 is wound around the bottom of the groove 141, and the excitation coil 142 has 20 to 50 turns, preferably 30 turns; the spring 160 is sheathed on the outside of the working cylinder 110 . Of course, it also includes: a first connecting rod 170, one end of which is connected to the axle 171, and the other end is connected to the bottom of the working cylinder 110;

In the present invention, the damping fluid is a magnetorheological fluid, and when the magnetic field strength becomes larger, the viscous of the magnetorheological fluid also becomes larger.

In the present invention, it also includes: a speed sensor, which is arranged on the outer wall of the working cylinder 110, for detecting the running speed of the vehicle; a weight sensor, which is arranged on the axle 171, for detecting the weight of the vehicle; an infrared sensor , which is arranged at both ends of the spring 160, for detecting the length of the spring 160; a vibration sensor, which is arranged on the outer wall of the working cylinder 110, for detecting the vibration amplitude of the automobile; a controller, which is connected with the speed Sensor, weight sensor, infrared sensor, vibration sensor and excitation coil 142 are connected, are used to receive the detection data of described speed sensor, weight sensor, infrared sensor and vibration sensor and control described excitation coil 142 to work, mainly control the passage in excitation coil The magnitude and frequency of the alternating current.

working principle:

During the driving process of the car, due to the excitation vibration of the road surface, the relative movement of the piston and the working cylinder occurs. Due to the different vibration intensity, the pressure on the spring is also different. The infrared sensor detects the real-time length of the spring, and according to the stiffness coefficient and initial length of the spring. Get the pressure of the spring at this moment. The controller receives the pressure change of the spring, and then controls the magnitude of the alternating current passing through the exciting coil. When the pressure is high, the controller controls the alternating current passing through the exciting coil to be larger, and thus the magnetic field is also stronger. Under the action of an external magnetic field, the magnetically polarized molecules in the magnetorheological fluid move directionally along the direction of the magnetic field, so that the particles connect end to end to form a chain or network, thereby changing the flow characteristics of the magnetorheological fluid. When the external magnetic field is strong, the fluidity of the magnetorheological fluid becomes weaker (that is, the viscosity becomes larger), and the flow ability of the magnetorheological fluid in the damping channel becomes weaker, which can better transfer the pressure on the spring and maintain the driving stability and stability of the car. comfort.

The variable damping automobile hydraulic shock absorber of the present invention can change the damping of the shock absorber during the running of the vehicle, thereby improving driving comfort and stability, and also increasing the service life of parts.

The present invention also provides a control method of a variable damping automobile hydraulic shock absorber, including:

The weight of the vehicle and the real-time length of the spring are collected by the above sensors. According to experience, the controller controls the magnitude of the alternating current passing through the excitation coil as follows:

Among them, I is the size of the alternating current passing through the excitation coil, r is the radius of the excitation coil, π is the circumference ratio, k is the stiffness coefficient of the spring, D ₀ is the inner diameter of the working cylinder, d is the width of the damping channel, η ₀ is the viscosity of the damping fluid when there is no external magnetic field, y is the distance from a point in the damping fluid to the central axis of the working cylinder, ξ is the balance coefficient, x ₀ is the initial length of the spring, x is the real-time length of the spring, and M is the weight of the vehicle , g is the acceleration due to gravity.

The frequency of the alternating current is 60Hz.

The present invention also includes: when the automobile is running, the balance coefficient ξ is regulated based on the BP neural network, including the following steps:

Step 1: Establish a BP neural network model;

The BP network architecture adopted by the present invention is composed of three layers. The first layer is the input layer, with n nodes in total, corresponding to n detection signals representing the driving state of the vehicle, and these signal parameters are given by the data preprocessing module. The second layer is the hidden layer (middle layer), with a total of m nodes, which is determined in an adaptive manner by the training process of the network. The third layer is the output layer, with a total of p nodes, determined by the actual output response of the system.

The mathematical model of the network is:

Input layer vector: x=(x ₁ ,x ₂ ,…,x _n ) ^T

Middle layer vector: y=(y ₁ ,y ₂ ,…,y _m ) ^T

Output layer vector: z=(z ₁ ,z ₂ ,…,z _p ) ^T

In the present invention, the number of nodes in the input layer is n=5, and the number of nodes in the output layer is p=1. The number of hidden layer nodes m is estimated by the following formula:

According to the sampling period, the 5 parameters to be input are: x ₁ is the vehicle weight coefficient, x ₂ is the spring length difference coefficient, x ₃ is the vehicle speed coefficient, x ₄ is the amplitude coefficient of the vehicle, and x ₅ is the magnetic permeability of the damping fluid coefficient;

Since the data acquired by sensors belong to different physical quantities, their dimensions are different. Therefore, before the data is fed into the neural network, the data needs to be normalized to a number between 0-1.

Specifically, for the vehicle weight M, after normalization, the weight coefficient x ₁ is obtained:

Among them, M _min and M _max are the minimum weight and maximum weight of the vehicle respectively.

Similarly, for the difference Δx between the initial length of the spring and the real-time length, after normalization, the spring length difference coefficient x ₂ is obtained:

Among them, Δx _min and Δx _max are the minimum and maximum differences between the initial length of the spring and the real-time length, respectively.

For the vehicle speed v, after normalization, the vehicle speed coefficient x ₃ is obtained:

Among them, v _min and v _max are the minimum vehicle speed and the maximum vehicle speed respectively.

For the amplitude A of the car, after normalization, the amplitude coefficient x ₄ of the car is obtained:

Among them, A _min and A _max are the minimum amplitude and maximum amplitude of the car respectively.

For the permeability μ of the damping fluid, after normalization, the permeability coefficient x ₅ of the damping fluid is obtained:

Among them, μ _min and μ _max are the minimum and maximum permeability of the damping fluid that the shock absorber can use, respectively.

One parameter of the output signal is expressed as: z ₁ is the adjustment coefficient of the balance coefficient;

The adjustment coefficient z ₁ of the balance coefficient is expressed as the ratio of the balance coefficient in the next sampling period to the maximum balance coefficient set in the current sampling period, that is, in the ith sampling period, the collected balance coefficient is ξ _i , through After the BP neural network outputs the balance coefficient adjustment coefficient z ₁ ⁱ of the ith sampling period, control the balance coefficient in the i+1 sampling period to ξ _i+1 so that it satisfies ξ _i+1 = z ₁ ⁱ ξ _max ;

Step 2: Carry out the training of BP neural network.

After the BP neural network node model is established, the BP neural network can be trained. Obtain training samples according to the empirical data of the product, and given the connection weight w _ij between input node i and hidden layer node j, the connection weight w _jk between hidden layer node j and output layer node k, implicit The threshold θ _j of layer node j, and the thresholds w _ij , w _jk , θ _j , θ _k of output layer node k are all random numbers between -1 and 1.

During the training process, the values of w _ij and w _jk are constantly revised until the system error is less than or equal to the expected error, and the training process of the neural network is completed.

As shown in Table 1, a set of training samples and the values of each node in the training process are given.

Table 1 The values of each node in the training process

Step 3, collecting data and operating parameters into the neural network to obtain the regulation coefficient;

The trained artificial neural network is solidified in the chip, enabling the hardware circuit to have prediction and intelligent decision-making functions, thus forming intelligent hardware. After the intelligent hardware is powered on and started, the shock absorber control and adjustment system starts to operate, and the shock absorber control and adjustment system starts to operate with an empirically determined initial value, that is, the initial value of the balance coefficient is ξ ₀ =0.8ξ _max . In the present invention, the The maximum balance coefficient ξ _max of the shock absorber set above = 1;

At the same time, the magnetic permeability μ of the damping fluid is known, and the sensor is used to measure the initial vehicle weight M ₀ , the initial spring length difference Δx ₀ , the initial vehicle speed v ₀ and the initial amplitude A ₀ of the vehicle. By normalizing the above parameters, BP is obtained The initial input vector for the neural network The initial output vector is obtained through the operation of the BP neural network

Step 4: Get the initial output vector After that, the balance coefficient can be adjusted so that the balance coefficient of the next sampling period is:

ξ ₁ = z ₁ ⁰ ξ _max ;

Obtain the vehicle weight M in the i-th sampling period, the difference between the initial length of the spring and the real-time length Δx, the vehicle speed v and the amplitude A of the vehicle through the sensor, and obtain the input vector of the i-th sampling period by normalization The output vector z ⁱ =(z ₁ ⁱ ) of the i-th sampling period is obtained through the operation of the BP neural network, and then the balance coefficient is controlled and adjusted so that the balance coefficient at the i+1 sampling period is:

ξ _i+1 = z ₁ ⁱ ξ _max ,

Through the above settings, the sensor monitors the driving status of the car and the operating status of the shock absorber in real time, and uses the BP neural network algorithm to regulate the balance coefficient, making the car driving more stable and comfortable.

The control method of the variable damping automotive hydraulic shock absorber of the present invention controls the magnitude of the current of the exciting coil in the damper according to the empirical formula according to the spring compression state of the shock absorber; The magnitude of the current is controlled so that the magnitude of the generated magnetic field is controllable. The viscosity of the damping fluid (magneto-rheological fluid) in the shock absorber changes according to the magnetic field, and the resulting damping coefficient is also different. Therefore, according to the compression of the spring The state can control the damping size of the shock absorber to improve driving comfort and stability. The present invention can also regulate the balance coefficient according to the running state of the vehicle and the road conditions during the driving process of the vehicle, so that the driving of the vehicle is more stable and comfortable.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (10)

1. a kind of damping can be changed automobile hydraulic shock-damping device, which is characterized in that including：

Working cylinder is internally provided with flowable damping fluid；

Piston rod is arranged in the working cylinder and can be axially moved along the working cylinder；

Piston is arranged on the piston rod, damping is provided between the piston outer periphery face and the working cylinder internal face Channel is used for the circulation of the damping fluid；

Groove, circumferentially disposed in the middle part of the piston, the bottom portion of groove is circumferentially wound magnet exciting coil, the magnet exciting coil For 20~50 circles；

Spring is set in outside the working cylinder.

2. damping as described in claim 1 can be changed automobile hydraulic shock-damping device, which is characterized in that further include：

First connecting rod, one end connect vehicle bridge, and the other end connects the working cylinder bottom；

Second connecting rod, one end connect automotive suspension, and the other end connects the piston rod.

3. damping as claimed in claim 2 can be changed automobile hydraulic shock-damping device, which is characterized in that further include：

Velocity sensor is arranged in the working cylinder outside wall surface, for detecting automobile driving speed；

Weight sensor is arranged in the vehicle bridge, for detecting vehicle weight；

Infrared sensor, setting are used for the length of detection spring in the both ends of the spring；

Vibrating sensor is arranged in the working cylinder outside wall surface, the Oscillation Amplitude for detecting automobile；

Controller is connect with the velocity sensor, weight sensor, infrared sensor, vibrating sensor and magnet exciting coil, Described in detection data and control for receiving the velocity sensor, weight sensor, infrared sensor and vibrating sensor Magnet exciting coil works.

4. a kind of damping can be changed the control method of automobile hydraulic shock-damping device, which is characterized in that including：

Acquire the real time length of vehicle weight and spring, in controller control magnet exciting coil by the size of alternating current be：

Wherein, I be magnet exciting coil in by alternating current size, r be magnet exciting coil radius, π is pi, and k is bullet The stiffness factor of spring, D₀For the internal diameter of working cylinder, d is the width of damp channel, η₀It is damping fluid viscous in no externally-applied magnetic field Degree, y are the distance that working cylinder central axis is a little arrived in damping fluid, and ξ is coefficient of balance, x₀For the initial length of spring, x is bullet The real time length of spring, M are vehicle weight, and g is acceleration of gravity.

5. damping as claimed in claim 4 can be changed the control method of automobile hydraulic shock-damping device, which is characterized in that the alternation electricity The frequency of stream is 60Hz.

6. damping can be changed the control method of automobile hydraulic shock-damping device as described in claim 4 or 5, which is characterized in that work as automobile Coefficient of balance is regulated and controled based on BP neural network when driving, is included the following steps：

Step 1：The magnetic permeability μ of known damping fluid passes through sensor measurement car weight M, the initial length of spring according to the sampling period With the difference DELTA x of real time length, the amplitude A of speed v and automobile；

Step 2：Above-mentioned parameter is standardized successively, determines input layer vector x={ x of three layers of BP neural network₁,x₂,x₃, x₄,x₅}；Wherein x₁For car weight coefficient, x₂For length difference coefficient, x₃For speed coefficient, x₄Peak factor, x for automobile₅ For the magnetic conductance rate coefficient of damping fluid；

Step 3：The input layer DUAL PROBLEMS OF VECTOR MAPPING is to middle layer, the middle layer vector y={ y₁,y₂,…,y_m}；M is middle layer Node number；

Step 4：Obtain output layer vector z={ z₁}；Wherein, z₁For the adjustment factor of coefficient of balance, make

ξ_i+1=z₁ ⁱξ_max,

Wherein, z₁ ⁱFor ith sample period output layer vector parameter, ξ_maxFor the maximum coefficient of balance of the damper of setting.

7. damping as claimed in claim 6 can be changed the control method of automobile hydraulic shock-damping device, which is characterized in that the middle layer Node number m meets：Wherein n is input layer number, and p is output layer node number.

8. damping as claimed in claim 6 can be changed the control method of automobile hydraulic shock-damping device, which is characterized in that in the step In 2, the amplitude A of car weight M, length difference DELTA x, speed v and automobile carry out normalization formulae and are：

Wherein, x_jFor the parameter in input layer vector, X_jRespectively measurement parameter M, Δ x, v, A, j=1,2,3,4；X_jmaxAnd X_jmin Maximum value and minimum value in respectively corresponding measurement parameter；

The magnetic permeability μ of damping fluid carries out normalization formulae：

Wherein, x₅For the parameter in input layer vector, X₅The magnetic conductivity of damping fluid, X are used by damper_5minIt can for damper Minimum magnetic conductivity with the damping fluid used, X_5maxFor the maximum permeability for the damping fluid that damper can use.

9. damping as claimed in claim 8 can be changed the control method of automobile hydraulic shock-damping device, which is characterized in that in the step In 1, under initial operating state, coefficient of balance meets empirical value：

ξ₀=0.8 ξ_max；

Wherein, ξ₀For the initial balance coefficient of damper；ξ_maxFor the maximum coefficient of balance of the damper of setting.

10. damping as claimed in claim 9 can be changed the control method of automobile hydraulic shock-damping device, which is characterized in that the setting Damper maximum coefficient of balance ξ_max=1.