Three measures to suppress high-frequency vibration of the vehicle body and its parameter design method

Abstract

The present invention discloses a suspension structure and parameter design method for suppressing high-frequency vibration of a vehicle body by three measures in the automotive field. An existing stiffness-damping inertia autonomous controllable suspension and a wheel high-frequency dynamic vibration absorber are combined to form a suspension for suppressing high-frequency vibration of a vehicle body by three measures. On the basis of vehicle body mass, wheel mass and equivalent stiffness, the mass of the wheel high-frequency dynamic vibration absorber and the minimum stiffness of the suspension in comfort mode are determined according to automobile design requirements. The damping and inertia of the inertia tube, the stiffness and damping of the wheel high-frequency dynamic vibration absorber are optimized with the goal of minimizing the objective function. When the vehicle is traveling on a bad road, the high-frequency vibration suppression measure transmitted from the wheel to the vehicle body is expanded to three measures of wheel high-frequency dynamic vibration absorption, vibration isolation and anti-resonance vibration reduction that work in coordination with each other, so that the advantage of the wheel high-frequency dynamic vibration absorption measure in cutting the peak of the high-frequency vibration of the vehicle body and the advantage of the anti-resonance vibration reduction measure in narrowing the bandwidth of the high-frequency vibration frequency band of the vehicle body are organically combined, and the vibration of the vehicle body in the high-frequency vibration band is completely flattened.

Description

Technical Field

[0001] The present invention belongs to the field of automobile technology and relates to automobile suspension, in particular to a suspension structure which adopts three measures of vibration isolation, anti-resonance vibration reduction and wheel dynamic vibration absorption to suppress high-frequency vibration of a vehicle body. Background Art

[0002] Suspension is a critical structural and functional component of a vehicle. Its primary function is to attenuate high-frequency vibrations transmitted from the wheels to the vehicle body when the vehicle is traveling on rough roads, ensuring a comfortable ride for passengers. Traditional passive suspensions consist solely of elastic and damping elements, isolating and damping high-frequency vibrations transmitted from the wheels to the vehicle body through the elastic elements. However, to ensure high-speed driving safety, the suspension system's damping must be moderate, and the vibration suppression measures employed are limited. Consequently, traditional passive suspensions are less effective in suppressing high-frequency vibrations. The suspension provided in the document entitled "Autonomous Controllable Suspension of Stiffness, Damping and Inertia, Its Parameter Design and Working Method" with Chinese Patent Application No. 202310527973.X, in the autonomous control mode of intelligent switches, controls the suspension system to output greater stiffness, greater damping, and greater inertia based on the road excitation frequency when the vehicle is traveling on good roads, thereby achieving better driving safety, including better handling stability and rollover stability. When the vehicle is traveling on bad roads, the suspension system is controlled to output less stiffness, less damping, and less inertia, allowing the suspension to attenuate high-frequency vibrations transmitted from the wheels to the vehicle body through both isolation and anti-resonance vibration reduction. Compared to suspensions that only use isolation measures, this suspension can slightly reduce the peak amplitude-frequency characteristic of the vehicle body acceleration input to the road, but significantly reduces the peak frequency bandwidth, which has an effect on suppressing high-frequency vibrations of the vehicle body. Therefore, it still fails to completely flatten the high-frequency vibration band (i.e., the frequency band located at the natural frequency of the wheel vibration). The amplitude of the vehicle body acceleration to road input frequency characteristic within a frequency band (a multiple of the range).

[0003] On the basis of traditional passive suspension, a wheel dynamic vibration absorber consisting of a spring connected to a vibration-absorbing mass block is added to the wheel (or axle). In theory, it can absorb part of the vibration energy of the wheel, but the mass of the vibration-absorbing mass block is much smaller than the mass of the wheel. Under the traditional suspension damping setting conditions, the wheel dynamic vibration absorber suppresses the high-frequency vibration of the vehicle body and the effect is not ideal. For example, the dynamic vibration absorber provided in the document with Chinese patent application number 202211711163.1 and titled "Dynamic vibration absorber, body suspension monocoque structure and multiple dynamic vibration absorber body suspension" includes a main rubber part and a mass block connected to the body, the rubber part is arranged on the upper end surface of the mass block, and the mass block and the rubber part are installed on the body from bottom to top to absorb and eliminate the resonance of a specific frequency of the body, rather than to reduce the vibration of the entire high-frequency vibration band of the body. Even if it is installed on the wheel and used in conjunction with a traditional passive suspension having only elastic and damping characteristics, under the conditions of optimal damping and the combination of parameters of this dynamic vibration absorber, compared with only adopting vibration isolation measures, it is possible to significantly reduce the peak value of the amplitude-frequency characteristic of the body acceleration input to the road surface (i.e., the resonance peak value at the natural frequency of the wheel vibration), but it is not possible to obtain the effect of suppressing the high-frequency vibration of the body within the entire high-frequency vibration band of the body, nor is it possible to completely flatten the high-frequency vibration band (i.e., the resonance peak value at the natural frequency of the wheel vibration). The amplitude of the vehicle body acceleration to road input frequency characteristic within a frequency band (a multiple of the range). Summary of the Invention

[0004] In view of the problem that the above-mentioned traditional passive suspension cannot completely flatten the high-frequency vibration peak of the vehicle body and cannot obtain better high-frequency vibration suppression effect of the vehicle body, based on the Chinese patent application number 202310527973.X and the name of "Stiffness Damping Inertia Autonomous Controllable Suspension and Its Parameter Design and Working Method", the present invention provides a suspension structure that uses three measures of vibration isolation, anti-resonance vibration reduction and wheel dynamic vibration absorption to suppress the high-frequency vibration of the vehicle body. The present invention also provides a key parameter design method of the suspension structure to obtain the optimal high-frequency vibration suppression effect of the vehicle body.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the suspension structure of the present invention for suppressing high-frequency vibration of the vehicle body by three measures is as follows: it includes a cylinder, the upper end of the cylinder body of the cylinder is fixedly connected to the vehicle body through an upper connecting device, the cylinder is connected to the inertia tube, the adjustable flow valve, the intelligent switch, the second solenoid valve and the second oil-gas chamber in sequence through an oil pipe, the first solenoid valve is connected in series with the first oil-gas chamber and then in parallel to the two ends of the series-connected adjustable flow valve and intelligent switch, the intelligent switch is connected to the suspension domain controller through a signal line, the suspension domain controller is respectively connected to the normally closed first and second solenoid valves through control lines, the interior of the cylinder is sealed and slidably connected to the plunger rod, the lower end of the plunger rod extends downward out of the cylinder and is fixedly connected to the wheel through a third connecting device and a lower connecting device in sequence, the third connecting device is also fixedly connected to a wheel high-frequency dynamic vibration absorber composed of a mass block and an elastic element, the lower end of the elastic element is fixedly connected to the third connecting device, and the upper end of the elastic element is fixedly connected to the lower end of the mass block.

[0006] Furthermore, the elastic element is a coaxial rubber spring, and the mass block is a coaxial mass block. The coaxial rubber spring and the coaxial mass block are both gap-mounted on the outside of the oil cylinder and the plunger rod. The lower end of the coaxial rubber spring is fixedly connected to the third connecting device, and the upper end is fixedly connected to the coaxial mass block. When the suspension is working, the coaxial rubber spring and the coaxial mass block do not contact the oil cylinder and the vehicle body. The coaxial rubber spring provides the stiffness and damping required for the operation of the wheel high-frequency dynamic vibration absorber.

[0007] Furthermore, the elastic element is an off-axis rubber spring, and the mass block is an off-axis mass block. The lower end of the off-axis rubber spring is fixedly connected to the third connecting device, and the upper end is fixedly connected to the off-axis mass block. The central axes of the off-axis mass block and the off-axis rubber spring are collinear, parallel to the central axes of the cylinder and the plunger rod, but not collinear. When the suspension is working, the off-axis rubber spring and the off-axis mass block do not contact the cylinder and the vehicle body. The off-axis rubber spring provides the stiffness and damping required for the operation of the high-frequency dynamic vibration absorber of the wheel.

[0008] Furthermore, the elastic element is composed of a coil spring, and the mass block is an off-axis mass block. The coil spring is coaxially sleeved on the outside of the shock absorber. The lower ends of the coil spring and the shock absorber are fixedly connected to the third connecting device, and the upper ends are fixedly connected to the off-axis mass block. The central axes of the coil spring, shock absorber and off-axis mass block are collinear, but are parallel to the central axes of the cylinder and the plunger rod but not collinear. When the suspension is working, it does not contact the cylinder and the vehicle body.

[0009] The technical solutions adopted in the parameter design method of the suspension structure for suppressing high-frequency vibration of the vehicle body by the three measures are:

[0010] Step 1): Calculate the wheel high-frequency dynamic vibration absorber mass m based on the wheel mass m1 d , according to the vehicle body mass m2 and the vehicle body vibration natural frequency f in comfort mode2c Calculate the minimum suspension stiffness k in comfort mode 2c ;

[0011] Step 2): Based on the vehicle body mass m2 and the minimum suspension stiffness k 2c Determine the inertia tube damping c 2c The value range is based on the mass m of the wheel high-frequency dynamic vibration absorber. d Determine the inertia of the pipe m e The value range is based on the wheel vertical equivalent stiffness k1, the minimum stiffness of the suspension k 2c , wheel high-frequency dynamic vibration absorber mass m d , the wheel mass m1 determines the stiffness k of the wheel high-frequency dynamic vibration absorber d The value range is based on the vehicle body mass m2 and the minimum suspension stiffness k 2c Determine the wheel high-frequency dynamic vibration absorber damping c d The value range of

[0012] Step 3) Based on the mass m of the wheel high-frequency dynamic vibration absorber d , minimum suspension stiffness k 2c 、Inertia tube damping c 2c 、habitual capacity management habitual capacity m e , wheel high-frequency dynamic vibration absorber stiffness k d and wheel dynamic vibration absorber damping c d Construct the regularized stiffness matrix K and the regularized damping matrix C, then construct the structural matrix A of the state equation describing the vertical motion of the suspension system and the complex matrix F describing the vertical state variable velocity of the suspension system, and finally obtain the optimization objective function;

[0013] Step 4): Take the minimum optimized inertia tube damping c of the optimization objective function as 2c 、habitual capacity management habitual capacity m e , wheel high-frequency dynamic vibration absorber stiffness k d and wheel dynamic vibration absorber damping c d , and obtain the optimal parameters.

[0014] Furthermore, the objective function is optimized G q0 is the road roughness coefficient, u is the vehicle speed, F is the complex matrix describing the vertical state variable velocity of the suspension system, f 2c is the natural frequency of vehicle body vibration, and n0 is the reference spatial frequency.

[0015] The beneficial effects of the present invention after adopting the above technical solution are:

[0016] 1. The suspension of the present invention is composed of an existing stiffness, damping, and inertia autonomous controllable suspension and a wheel high-frequency dynamic vibration absorber. In the vehicle ride comfort mode, the suspension of the present invention has the following advantages compared with the suspension in the document with Chinese patent application number 202310527973.X, entitled "Stiffness, damping, and inertia autonomous controllable suspension, and its parameter design and working method": the suspension of the present invention adds a wheel high-frequency dynamic vibration absorber to the wheel, instead of fixing the dynamic vibration absorber on the vehicle body as in the structure in the document with Chinese patent application number 202211711163.1, entitled "Dynamic vibration absorber, vehicle body suspension single structure and multi-dynamic vibration absorber vehicle body suspension", which can only absorb and eliminate the resonance of a specific frequency of the vehicle body. Therefore, when the car is traveling on a bad road, the suspension control system of the present invention outputs smaller stiffness, smaller damping and smaller inertia. On the basis of the high-frequency dynamic vibration absorber of the wheel absorbing the high-frequency vibration of the wheel, the high-frequency vibration suppression measures transmitted from the wheel to the car body are expanded from the original two measures of vibration isolation and anti-resonance vibration reduction to three measures of wheel dynamic vibration absorption, vibration isolation and anti-resonance vibration reduction that work in a coordinated manner, thereby completely flattening the high-frequency vibration peak of the car body, effectively suppressing the high-frequency vibration of the car body, and making the car obtain good bad road ride comfort.

[0017] 2. The present invention coordinates the three measures of vibration absorption, vibration isolation and anti-resonance vibration reduction through the design of key suspension parameters. In addition to improving the vibration isolation performance, it organically combines the advantages of the wheel dynamic vibration absorption measure in reducing the peak of the high-frequency vibration of the vehicle body with the advantages of the anti-resonance vibration reduction measure in reducing the bandwidth of the high-frequency vibration of the vehicle body, completely flattening the natural frequency of the wheel vibration. The high-frequency vibration band of the vehicle body can achieve the best high-frequency vibration suppression effect of the vehicle body. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the suspension using the three measures described in the present invention to suppress high-frequency vibration of the vehicle body;

[0019] Figure 2 yes Figure 1 Schematic diagram of the first structure of the high-frequency dynamic vibration absorber for the middle wheel;

[0020] Figure 3 yes Figure 1 Schematic diagram of the second structure of the high-frequency dynamic vibration absorber of the middle wheel;

[0021] Figure 4 yes Figure 1 Schematic diagram of the third structure of the high-frequency dynamic vibration absorber of the middle wheel;

[0022] Figure 5 yes Figure 1 Diagram of the body vibration damping effect of the suspension shown.

[0023] In the figure: 1. Vehicle body; 2. Cylinder; 3. Plunger rod; 4. Lower connecting device; 5. Wheel; 6. Adjustable flow valve; 7. Intelligent switch; 8. Second solenoid valve; 9. Second oil-gas chamber; 10. First oil-gas chamber; 11. Suspension domain controller; 12. First solenoid valve; 13. Inertia tube; 14. Upper connecting device; 15. Third connecting device; 16. Wheel high-frequency dynamic vibration absorber; 17. Coaxial rubber spring; 18. Coaxial mass block; 19. Off-axis rubber spring; 20. Off-axis mass block; 21. Coil spring; 22. Shock absorber. DETAILED DESCRIPTION

[0024] See also Figure 1 The three measures described in the present invention suppress the high-frequency vibration of the vehicle body through the suspension, which is composed of the stiffness damping inertia autonomous controllable suspension and the wheel high-frequency dynamic vibration absorber 16 provided in the document with Chinese patent application number 202310527973.X and the name "Stiffness damping inertia autonomous controllable suspension and its parameter design and working method". The stiffness damping inertia autonomous controllable suspension includes a cylinder 2, the upper end of the cylinder body of the cylinder 2 is fixedly connected to the vehicle body 1 through the upper connecting device 14, the interior of the cylinder 2 is sealed and slidably connected to the plunger rod 3, the upper end of the plunger rod 3 extends upward into the cylinder 2, and the lower end of the plunger rod 3 extends downward out of the cylinder 2, and is fixedly connected to the wheel 5 through the third connecting device 15 and the lower connecting device 4 in turn. In this way, the cylinder 2 and the plunger rod 3 are installed from top to bottom between the vehicle body 1 and the wheel 5 through the upper connecting device 14 and the lower connecting device 4. The cylinder 2 cavity, except for the plunger rod 3, is filled with oil. Oil pipes connect the cylinder 2 to the inertia pipe 13, the adjustable throttle valve 6, the intelligent switch 7, the second solenoid valve 8, and the second oil-gas chamber 9. The first solenoid valve 12 is connected in series with the first oil-gas chamber 10 and then in parallel to the adjustable throttle valve 6 and the intelligent switch 7. The first and second solenoid valves 12 and 8 are normally closed. The intelligent switch 7 is connected via a signal line to the suspension domain controller 11, which is in turn connected to the vehicle's upper chassis system controller via a signal line. The suspension domain controller 11 is connected to the normally closed first and second solenoid valves 12 and 8 via control lines. The intelligent switch 7 uses the intelligent switch described in Chinese invention patent application number 202211360329.X, entitled "Intelligent Self-Powered Active Suspension with Multi-Level Height Adjustability and Its Operating Method."

[0025] A damped high-frequency wheel dynamic vibration absorber 16 is also fixedly connected to the third coupling device 15. This wheel high-frequency dynamic vibration absorber 16 is sequentially fixedly connected to the third coupling device 15, the lower coupling device 4, and the wheel 5. The wheel high-frequency dynamic vibration absorber 16 consists of a mass and an elastic element. The lower end of the elastic element is fixedly connected to the third coupling device 15, while the upper end of the elastic element is fixedly connected to the lower end of the mass. The upper end of the mass does not contact or connect to the vehicle body 1.

[0026] The elastic element in the wheel high-frequency dynamic vibration absorber 16 can be a rubber spring or a coil spring, and can be arranged parallel to the cylinder 2 and the plunger rod 3 with the same axis or with different axes. The three structures of the wheel high-frequency dynamic vibration absorber 16 are as follows:

[0027] See also Figure 2 The first structure of the wheel high-frequency dynamic vibration absorber 16 shown is composed of a coaxial rubber spring 17 and a coaxial mass block 18, both of which are hollow structures. The coaxial rubber spring 17 and the coaxial mass block 18 are both loosely mounted on the outside of the cylinder 2 and the plunger rod 3. The lower end of the coaxial rubber spring 17 is fixedly connected to the third connecting device 15, and the upper end is fixedly connected to the coaxial mass block 18. The coaxial rubber spring 17 and the coaxial mass block 18 constitute the structure of the wheel high-frequency dynamic vibration absorber 16. When the suspension is working, it does not contact the cylinder 2 and the vehicle body 1. The coaxial rubber spring 17 provides stiffness and damping for the wheel high-frequency dynamic vibration absorber 16.

[0028] See also Figure 3 The second configuration of the wheel high-frequency dynamic vibration absorber 16 shown in the figure consists of an off-axis rubber spring 19 and an off-axis mass block 20. The lower end of the off-axis rubber spring 19 is fixedly connected to the third coupling device 15, and the upper end is fixedly connected to the off-axis mass block 20. The off-axis mass block 20 and the off-axis rubber spring 19 are parallel to the central axis of the cylinder 2 and the plunger rod 3, but not collinear. When the suspension is operating, the off-axis rubber spring 19 and the off-axis mass block 20 do not contact the cylinder 2 or the vehicle body 1. The off-axis rubber spring 19 provides stiffness and damping for the wheel high-frequency dynamic vibration absorber 16.

[0029] See also Figure 4 The third structure of the wheel high-frequency dynamic vibration absorber 16 shown in the figure consists of a coil spring 21, a shock absorber 22, and another off-axis mass 20. The lower ends of the coil spring 21 and shock absorber 22 are fixedly connected to the third coupling device 15, and the upper ends of the coil spring 21 and shock absorber 22 are fixedly connected to the other off-axis mass 20. The coil spring 21 is sleeved outside the shock absorber 22. The coil spring 21, shock absorber 22, and the other off-axis mass 20 are parallel to, but not collinear with, the central axis of the cylinder 2 and the plunger rod 3. When the suspension is operating, the coil spring 21 and off-axis mass 20 do not contact the cylinder 2 or the vehicle body 1. The coil spring 21 and shock absorber 22 provide stiffness and damping, respectively, for the wheel high-frequency dynamic vibration absorber 16.

[0030] The present invention primarily designs six key parameters for the suspension in comfort mode: minimum suspension stiffness, inertia value of the inertia tube 13, damping value of the inertia tube 13, and mass, stiffness, and damping of the wheel high-frequency dynamic vibration absorber 16. The design of key suspension parameters in comfort mode is described using a quarter-car model as an example:

[0031] According to the automobile design and development process, the known initial parameters of the automobile suspension are obtained: the body mass m2, the wheel mass m1 and the wheel vertical equivalent stiffness k1, the automobile speed u is defined, and the parameters describing the road surface roughness are defined as: the road surface roughness coefficient is G q0 , reference spatial frequency n0 = 0.1m -1 .

[0032] The mass m of the wheel high-frequency dynamic vibration absorber 16 is calculated based on the wheel mass m1. d :

[0033] m d =n1m1,

[0034] n1 is a coefficient, which is determined based on the specific conditions of the suspension installation space in the vehicle design, and is generally between 0.1 and 0.4.

[0035] According to the vehicle body mass m2 and the vehicle body vibration natural frequency f in comfort mode 2c , calculate the minimum suspension stiffness k in comfort mode by the following formula 2c for:

[0036] k 2c =m2(2πf 2c ) 2 ,

[0037] Among them, the natural frequency of vehicle body vibration in comfort mode is f 2c It is determined based on the vehicle body mass m2, wheel mass m1, wheel vertical equivalent stiffness k1 and the requirements for improving vehicle ride comfort, and determines the vehicle body vibration natural frequency f in comfort mode. 2c The value is between 1 and 1.2.

[0038] According to the vehicle body mass m2 and the minimum suspension stiffness k 2c Determine the damping c of the inertial tube 13 2c The value range is (0.01~0.4)

[0039] According to the mass m of the wheel high frequency dynamic vibration absorber 16 d Determine the inertia m of the inertia tube 13 e The value range is: (0.4~3)m d .

[0040] According to the wheel vertical equivalent stiffness k1 and the minimum stiffness of the suspension k 2c , the mass of the wheel high-frequency dynamic vibration absorber 16m d The wheel mass m1 determines the stiffness k of the wheel high-frequency dynamic vibration absorber 16 d The value range of is:

[0041] According to the vehicle body mass m2 and the minimum suspension stiffness k 2c Determine the damping c of the wheel high-frequency dynamic vibration absorber 16 d The value range of is:

[0042] Therefore, among the above six key parameters, only the mass m of the wheel high-frequency dynamic vibration absorber 16 is important. d =n1m1 and minimum suspension stiffness k 2c =m2(2πf 2c ) 2 It is designed based on the specific limitations of the suspension installation space and the requirements for improving the ride comfort of the car, and the damping c of the inertia tube 13 2c 、The inertia of the inertia tube 13 m e , the stiffness k of the wheel high-frequency dynamic vibration absorber 16 d and the damping c of the wheel dynamic vibration absorber 16 d The range of values ​​for these four key parameters is first determined, and then the variance of the vehicle body acceleration is minimized and optimized. In order to obtain the best effect of high-frequency vibration of the vehicle body, the range values ​​of the four key parameters are further optimized: first, the regularized stiffness matrix K and the regularized damping matrix C are constructed based on these six key parameters, and the structural matrix A of the state equation describing the vertical motion of the suspension system is constructed to construct this. Further, based on this structural matrix A of the state equation describing the vertical motion of the suspension system, the complex matrix F describing the vertical state variable velocity of the suspension system is constructed to obtain the optimization objective function. Finally, the minimum value of the optimization objective function is obtained to optimize these four key parameters. Specifically:

[0043] According to the wheel mass m1, the vehicle body mass m2, the inertia m of the inertia tube 13 e , the mass of the wheel high-frequency dynamic vibration absorber 16m d , wheel vertical equivalent stiffness k1, suspension minimum stiffness k 2c , the stiffness k of the wheel high-frequency dynamic vibration absorber 16 d The regularized stiffness matrix K is constructed as follows:

[0044]

[0045] At the same time, according to the wheel mass m1, the vehicle body mass m2, the inertia of the inertia tube 13 m e , the mass of the wheel high-frequency dynamic vibration absorber 16m d , the damping c of the wheel high-frequency dynamic vibration absorber 16 d , the damping c of the inertia tube 13 2c Construct the matrix regularization damping matrix C as follows:

[0046]

[0047] The structural matrix A of the state equation describing the vertical motion of the suspension system is constructed based on the regularized stiffness matrix K and the regularized damping matrix C:

[0048]

[0049] Where: 0 3×3 is a 3×3 zero matrix.

[0050] The complex matrix F describing the velocity of the vertical state variables of the suspension system is constructed and calculated based on the structural matrix A of the state equation of the vertical motion of the suspension system;

[0051] F=(j2πfI 6×6 -A) -1 (-I 6×1 )(j2πf) 2 ,

[0052] Where: j is an imaginary number, equal to I 6×6 , I 6×1 are 6×6 and 6×1 unit matrices respectively, and f is the natural frequency variable.

[0053] According to the working condition of the car driving on the bad road, determine the car's driving speed u and the road surface roughness coefficient G q0 These two parameters are the initial conditions for optimization. The specific values ​​have little effect on the optimization results. The bad road level can be D, G q0 =1024×10 -6 m 3 , the vehicle speed u can be selected between 40 and 60 km / h; if the bad road grade is E, G q0 =4096×10 -6 m 3 , the vehicle speed u can be selected between 20 and 40 km / h.

[0054] Based on the matrix F, the vehicle speed u and the road roughness coefficient G q0 , according to the natural frequency of the body vibration of the power spectrum density in the comfort mode Integrate the frequency band above times to construct the optimization objective function, that is, the standard deviation of the vehicle body acceleration

[0055]

[0056] To optimize the objective function The minimum value of the target is to use genetic algorithm to optimize the key parameters and obtain the optimal damping c of the inertial tube 13. 2c 、The inertia of the inertia tube 13 m e , the stiffness k of the wheel high-frequency dynamic vibration absorber 16 d, the damping c of the wheel high-frequency dynamic vibration absorber 16 d These four parameters complete the design of the six key parameters in the comfort mode. The vibration natural frequency of the wheel high-frequency dynamic vibration absorber 16 designed based on the key parameters is located within the resonant frequency band of the wheel 5 vibration natural frequency. Ultimately, the three measures of suspension elastic vibration isolation, suspension stiffness and inertia anti-resonance vibration reduction, and wheel high-frequency dynamic vibration absorber vibration absorption work in a coordinated manner to completely flatten the high-frequency vibration band (i.e., located within the wheel vibration natural frequency). The amplitude of the vehicle body acceleration to road input frequency characteristic within a frequency band (a multiple of the range).

[0057] When the designed suspension is working, when the car is driving at high speed on a good road, the intelligent switch 7 is autonomously controlled or the suspension domain controller 11 takes over the control, providing the suspension with greater stiffness, damping and inertia, so that the car can obtain better driving safety, and the wheel high-frequency dynamic vibration absorber 16 moves with the wheel 5. When the car is driving on a bad road, since the natural vibration frequency of the wheel high-frequency dynamic vibration absorber 16 is within the resonant frequency band of the natural vibration frequency of the wheel 5, the wheel high-frequency dynamic vibration absorber 16 absorbs the high-frequency vibration of the wheel 5. At this time, the intelligent switch 7 is autonomously controlled to provide the suspension with smaller stiffness, damping and inertia, that is, by reducing the suspension stiffness, the natural vibration frequency of the vehicle body is reduced, the vibration isolation effect of the suspension stiffness on the high-frequency vibration of the vehicle body 1 is improved, and the vibration isolation effect of the stiffness on the high-frequency vibration of the vehicle body 1 is maintained by reducing the suspension damping (increased damping will weaken the vibration isolation effect of the stiffness on the high-frequency vibration of the vehicle body 1), so that the anti-resonance frequency formed by the suspension stiffness and the inertia tube 13 is within the resonant frequency band of the natural vibration frequency of the wheel 5, so that the suspension performs anti-resonance vibration reduction on the high-frequency vibration of the vehicle body 1, thereby achieving the three measures of wheel dynamic vibration absorption, vibration isolation, and anti-resonance vibration reduction to completely flatten the high-frequency vibration peak of the vehicle body 1, thereby making the car obtain good ride comfort on bad roads.

[0058] In addition, an adjustable damper is connected in series with the intelligent switch 7 to provide high damping in the anti-resonance vibration reduction structure, increasing the ratio of inertia to damping in the orifice within the intelligent switch 7 and improving the intelligent switch 7's sensitivity to suspension vibration frequency. Specifically, the following steps are performed to achieve autonomous control of stiffness, damping, and inertia by the intelligent switch 7 and take over control by the chassis control system:

[0059] Step A: When the car accelerates, decelerates or turns sharply, the car's built-in chassis system controller inputs control signal A to the suspension domain controller 11 of the present invention. At this time, the logic value of the control signal A is 1. Otherwise, the logic value of the control signal A input to the suspension domain controller 11 is 0.

[0060] Step B: When the road excitation frequency on which the car is traveling is greater than the designed frequency threshold, the road surface unevenness drives the plunger rod 3 to move relative to the cylinder 2 at the same frequency as the road surface excitation frequency through the wheel 5 and the lower connecting device 4, and causes the oil in the cavity of the cylinder 2 to flow back and forth at the same flow rate as the road surface excitation frequency in the oil circuit of the cylinder 2, the inertia tube 13, the adjustable flow valve 6, the intelligent switch 7, and the first oil-gas chamber 10. The acceleration of the back-and-forth flow of the oil causes the inertia force generated on the inner measuring hole of the valve core of the intelligent switch 7 to push the contact piece, start the trigger switch, and output the trigger signal, that is, the intelligent switch 7 is triggered. When the intelligent switch 7 is triggered, the control signal B is input to the suspension domain controller 11. At this time, the logical value of the control signal B is 1.

[0061] When the road excitation frequency on which the vehicle is traveling is less than or equal to the designed frequency threshold, the acceleration of the oil flowing through the intelligent switch 7 is small. The acceleration of the oil flowing back and forth causes the inertial force generated on the inner metering hole of the valve core of the intelligent switch 7 to be unable to push the contact piece to trigger the switch to output a trigger signal, that is, the intelligent switch 7 is not triggered. When the intelligent switch 7 is not triggered, the control signal B is input to the suspension domain controller 11. At this time, the logical value of the control signal B is 0.

[0062] Step C: The suspension domain controller 11 receives the control signal A input from the chassis system controller and the control signal B input from the intelligent switch 7, and synchronously controls the normally closed first solenoid valve 12 and the second solenoid valve 8 according to the control rule (1-A)B. There are four control states:

[0063] State 1: When the logical values ​​of control signals A and B are both 1 (denoted as A=1, B=1), according to control rule (1-A)B, the output of suspension domain controller 11 is 0, maintaining the normally closed first solenoid valve 12 and second solenoid valve 8 closed. Specifically, when the vehicle experiences rapid acceleration, deceleration, or a sudden turn, and the road excitation frequency exceeds the designed frequency threshold, first solenoid valve 12 and second solenoid valve 8 remain closed.

[0064] State 2: When the logic value of control signal A is 1 and the logic value of control signal B is 0 (denoted as A=1, B=0), according to control rule (1-A)B, the output of suspension domain controller 11 is 0, maintaining the normally closed first solenoid valve 12 and second solenoid valve 8 in the closed position. Specifically, when the vehicle experiences rapid acceleration, deceleration, or a sudden turn, and the road excitation frequency is less than or equal to the designed frequency threshold, first solenoid valve 12 and second solenoid valve 8 remain closed.

[0065] State 3: When the logic value of control signal A is 0 and the logic value of control signal B is 1 (denoted as A=0, B=1), the output of suspension domain controller 11 is 1, controlling the normally closed first solenoid valve 12 and second solenoid valve 8 to open. Specifically, when the vehicle is not rapidly accelerating, decelerating, or turning, and the road excitation frequency is greater than the designed frequency threshold, first solenoid valve 12 and second solenoid valve 8 open.

[0066] State 4: When the logic value of control signal A is 0 and the logic value of control signal B is 0 (denoted as A=0, B=0), the output of suspension domain controller 11 is 0, and normally closed first solenoid valve 12 and second solenoid valve 8 are closed. Specifically, when the vehicle is not experiencing sudden acceleration, deceleration, or steering, and the road excitation frequency is less than or equal to the designed frequency threshold, first solenoid valve 12 and second solenoid valve 8 are closed.

[0067] In the aforementioned state 3, when the vehicle is not undergoing a sudden acceleration, deceleration, or steering operation, the chassis system controller inputs a control signal A with a logic value of 0 to the suspension domain controller 11. According to the control rule (1-A)B, the control quantity input to the first solenoid valve 12 and the second solenoid valve 8 by the suspension domain controller 11 is output by the intelligent switch 7 as a control signal B. At the same time, when the road surface excitation frequency is greater than the designed frequency threshold, the road surface unevenness drives the plunger rod 3 through the wheel 5 and the lower coupling device 4 to produce a movement with the same road surface excitation frequency relative to the cylinder 2, and causes the oil in the cylinder 2 to flow back and forth at the same flow rate as the road surface excitation frequency in the oil passage from the cylinder 2 through the inertia pipe 13, the adjustable flow valve 6, the intelligent switch 7 to the first oil-gas chamber 10. The acceleration of the back-and-forth flow of the oil generates an inertia force on the inner orifice of the intelligent switch 7, which pushes the contact piece to start the trigger switch to output a trigger signal, i.e., the intelligent switch 7 is triggered. When the intelligent switch 7 is triggered, the suspension The logic value of the control signal B input to the domain controller 11 is 1. At this time, the suspension domain controller 11 outputs the control quantity to the first solenoid valve 12 and the second solenoid valve 8, opening the first solenoid valve 12 and the second solenoid valve 8. At this time, the road surface unevenness drives the plunger rod 3 to move relative to the cylinder 2 at the same frequency as the road surface excitation through the wheel 5 and the lower connecting device 4, and causes the oil in the cylinder 2 to flow from the cylinder 2 through the inertia pipe 13 and the first solenoid valve 12 at the same flow rate as the road surface excitation frequency. A part of the oil flows directly into or out of the first oil-gas chamber 10, and the other part of the oil flows through the second solenoid valve 8. Then it flows into or out of the second oil-gas chamber 9. Therefore, the first oil-gas chamber 10 and the second oil-gas chamber 9 work in parallel to provide smaller stiffness, and the inertia tube 13 alone provides smaller damping. The inertia tube 13 alone provides smaller inertia, and controls the suspension system to output smaller stiffness, smaller damping and smaller inertia, that is, by reducing the suspension stiffness to reduce the natural frequency of vehicle body vibration to enhance the vibration isolation effect of the suspension stiffness on the high-frequency vibration of the vehicle body, by reducing the suspension damping to maintain the vibration isolation effect of the suspension stiffness on the high-frequency vibration of the vehicle body, so that the anti-resonance frequency of the suspension stiffness and the inertia tube is equal to the natural frequency of wheel vibration, and further The high-frequency vibration of the vehicle body is subjected to anti-resonance vibration reduction, and at the same time, the high-frequency dynamic vibration absorber 16 of the wheel 5 absorbs the high-frequency vibration of the wheel, thereby completely flattening the high-frequency vibration peak of the vehicle body 1 by using the three measures of wheel dynamic vibration absorption, vibration isolation, and anti-resonance vibration reduction, so that the car can obtain better ride comfort. At this time, the present invention does not require a traditional acceleration sensor and a controller for calculating the corresponding algorithm. Only the intelligent switch 7 is used to control the stiffness, damping and inertia of the suspension inside the suspension according to the change of the road excitation frequency, so as to realize autonomous control of the stiffness, damping and inertia within the suspension system.

[0068] In the cases of states 1, 2 and 4, the first solenoid valve 12 and the second solenoid valve 8 are not opened, and the road surface unevenness drives the plunger rod 3 to move relative to the oil cylinder 2 at the same frequency as the road surface excitation frequency through the wheel 5 and the lower connecting device 4, and causes the oil in the oil cylinder 2 to flow back and forth in the oil cylinder 2 through the inertia tube 13, the adjustable flow valve 6, the intelligent switch 7 to the first oil-gas chamber 10 at the same flow rate as the road surface excitation frequency. The first oil-gas chamber 10 alone provides greater rigidity, and the inertia tube 13, the adjustable flow valve 6 and the intelligent switch 7 jointly provide greater rigidity. At the same time, greater damping is provided. The inertia tube 13 and the intelligent switch 7 jointly provide greater inertia, controlling the suspension system to output greater stiffness, greater damping and greater inertia, so that the car can obtain better driving safety including handling stability and rollover stability. At this time, the present invention does not require a traditional acceleration sensor and a controller that calculates the corresponding algorithm. The intelligent switch 7 controls the stiffness, damping and inertia of the suspension inside the suspension according to the change of the road excitation frequency, and realizes autonomous control of stiffness, damping and inertia inside the suspension system.

[0069] In the case of state 1 and state 2, when the car performs a sudden acceleration, a sudden deceleration, or a sudden steering operation, the chassis system controller inputs a control signal A with a logic value of 1 to the suspension domain controller 11. According to the control rule (1-A)B, no matter what the output control signal B of the intelligent switch 7 is, the control amount input to the first solenoid valve 12 and the second solenoid valve 8 by the suspension domain controller 11 is 0. The road surface roughness drives the plunger rod 3 to generate a movement with the same frequency as the road surface excitation relative to the cylinder 2 through the wheel 5 and the lower connecting device 4, and causes the cylinder 2 to move at a frequency equal to that of the road surface excitation. The oil in the oil cylinder 2 flows back and forth between the oil cylinder 2, the inertia tube 13, the adjustable flow valve 6, the intelligent switch 7, and the first oil-gas chamber 10 at a flow rate equal to the road surface excitation frequency. The first oil-gas chamber 10 alone provides greater stiffness, while the inertia tube 13, the adjustable flow valve 6, and the intelligent switch 7 together provide greater damping. The inertia tube 13 and the intelligent switch 7 together provide greater inertia, that is, the suspension system is controlled to output greater stiffness, greater damping, and greater inertia, enabling the chassis system controller to take over suspension control, thereby ensuring good driving safety for the vehicle.

[0070] For example, given the following parameters: vehicle body mass m2 = 400 kg, wheel mass m1 = 58.5 kg, and wheel vertical equivalent stiffness k1 = 300,000 N / m, the vehicle body vibration natural frequency f in comfort mode is determined based on vehicle usage requirements. 2c =1.1Hz, wheel high frequency dynamic vibration absorber mass m d =7kg. The driving condition is that the car is driving on a D-grade road at a speed of u = 50km / h, then G q0 =1024×10 -6 m 3The results of calculating and optimizing other parameters are as follows: The minimum stiffness k of the suspension in comfort mode 2c =19108N / m, inertia of the inertia tube c2 = 125.81N·s / m, inertia of the inertia tube m e =4.5604kg, wheel high-frequency dynamic vibration absorber stiffness k d =33000N / m, wheel high frequency dynamic vibration absorber stiffness c d =213N·s / m.

[0071] According to the above parameter values, the amplitude-frequency characteristics of the vehicle acceleration to the road surface of the four suspensions with only vibration isolation measures, two measures of vibration isolation and anti-resonance vibration reduction, two measures of vibration isolation and wheel dynamic vibration absorption, and three measures are shown. Figure 5 shown. Figure 5 It shows that the four types of suspension have the same effect on the vibration reduction of the body vibration natural frequency range, but have obvious differences in the vibration reduction effect of the body high-frequency vibration within the natural frequency range of wheel vibration. Among them, the peak value of the amplitude-frequency characteristic of the body acceleration to the road input when only vibration isolation measures are adopted is the highest, and the peak value of the amplitude-frequency characteristic of the body acceleration to the road input when both vibration isolation and anti-resonance vibration reduction measures are adopted is second, but the frequency bandwidth of the amplitude-frequency characteristic of the body acceleration to the road input is greatly reduced. All three measures are taken in the high-frequency vibration band (i.e., in the natural frequency range of wheel vibration). The peak value of the amplitude-frequency characteristic of the vehicle body acceleration input to the road surface is completely flattened within the frequency band of the vibration isolation and vibration absorption measures. Although the peak value of the amplitude-frequency characteristic of the vehicle body acceleration input to the road surface when both vibration isolation and vibration absorption measures are taken is lower than that when both vibration isolation and anti-resonance vibration reduction measures are taken, there is still an amplitude of the amplitude-frequency characteristic of the vehicle body acceleration input to the road surface that has not been completely flattened, and the frequency band is significantly wider. Given that the variance of the vehicle body acceleration is equal to the integral of its power spectrum density over frequency, the vehicle body high-frequency suppression effect of the vibration isolation and vibration absorption measures is basically equivalent to that of the vibration isolation and anti-resonance vibration reduction measures, and is significantly inferior to the best vehicle body high-frequency suppression effect so far achieved by completely flattening the amplitude of the amplitude-frequency characteristic of the vehicle body acceleration input to the road surface within the high-frequency vibration band using all three measures. This shows that only the suspension system provided by the present invention, which is composed of an oil-gas spring with autonomously adjustable stiffness, damping and inertia and a wheel high-frequency dynamic vibration absorber, has the three measures of suppressing high-frequency vibration of the vehicle body, namely vibration isolation, anti-resonance vibration reduction and wheel dynamic vibration absorption. In addition, the suspension parameters determined by the parameter determination method provided by the present invention, in addition to reducing the suspension stiffness to improve the vibration isolation function, coordinate the two measures of anti-resonance vibration reduction and wheel dynamic vibration absorption, and organically combine the vehicle body high-frequency vibration peak clipping advantage of the wheel dynamic vibration absorption measure with the vehicle body high-frequency vibration band narrowing advantage of the anti-resonance vibration reduction measure, so as to completely flatten the amplitude of the vehicle body acceleration input amplitude-frequency characteristic of the road surface within the high-frequency vibration band, and obtain the best vehicle body high-frequency vibration suppression effect so far.

Claims

1. A method for designing suspension structure parameters for suppressing high-frequency vibration of a vehicle body using three measures. The suspension structure includes a cylinder, the upper end of the cylinder body of which is fixedly connected to the vehicle body via an upper coupling device. The cylinder is sequentially connected to an inertia tube, an adjustable flow valve, an intelligent switch, a second solenoid valve, and a second oil-gas chamber via an oil pipe. The first solenoid valve is connected in series with the first oil-gas chamber and then in parallel to both ends of the series-connected adjustable flow valve and intelligent switch. The intelligent switch is connected to a suspension domain controller via a signal line, and the suspension domain controller is connected to the normally closed first and second solenoid valves via control lines. The cylinder is sealed internally and slidably connected to a plunger rod. The method is characterized by: The lower end of the plunger rod extends downwardly out of the oil cylinder and is fixedly connected to the wheel through the third connecting device (15) and the lower connecting device (4) in sequence. The third connecting device (15) is also fixedly connected to a wheel high-frequency dynamic vibration absorber (16) composed of a mass block and an elastic element. The lower end of the elastic element is fixedly connected to the third connecting device (15), and the upper end of the elastic element is fixedly connected to the lower end of the mass block. The parameters are designed according to the following steps: Step 1): Calculate the mass m of the wheel high-frequency dynamic vibration absorber (16) based on the wheel mass m1 d , according to the vehicle body mass m2 and the vehicle body vibration natural frequency f in comfort mode 2c Calculate the minimum suspension stiffness k in comfort mode 2c ; Step 2): Based on the vehicle body mass m2 and the minimum suspension stiffness k 2c Determine the inertia tube damping c 2c The value range is based on the mass m of the wheel high-frequency dynamic vibration absorber (16). d Determine the inertia of the pipe m e The value range is based on the wheel vertical equivalent stiffness k1, the minimum stiffness of the suspension k 2c 、Wheel high frequency dynamic vibration absorber (16) mass m d The wheel mass m1 determines the stiffness k of the wheel high-frequency dynamic vibration absorber (16) d The value range is based on the vehicle body mass m2 and the minimum suspension stiffness k 2c Determine the wheel high-frequency dynamic vibration absorber (16) damping c d The value range of Step 3) Based on the mass m of the wheel high frequency dynamic vibration absorber (16) d , minimum suspension stiffness k 2c 、Inertia tube damping c 2c 、habitual capacity management habitual capacity m e , wheel high frequency dynamic vibration absorber (16) stiffness k d and the wheel dynamic vibration absorber (16) damping c d Construct the regularized stiffness matrix K and the regularized damping matrix C, then construct the structural matrix A of the state equation describing the vertical motion of the suspension system and the complex matrix F describing the vertical state variable velocity of the suspension system, and finally obtain the optimization objective function; the regularized stiffness matrix The matrix regularization damping matrix The structural matrix The complex matrix F=(j2πfI 6×6 -A) -1 (-I 6×1 )(j2πf) 2 , 0 3×3 is a 3×3 zero matrix, I 6×6 , I 6×1 are 6×6 and 6×1 identity matrices respectively, and f is the natural frequency variable; Step 4): Find the minimum optimized inertia tube damping c of the optimization objective function 2c 、habitual capacity management habitual capacity m e , wheel high frequency dynamic vibration absorber (16) stiffness k d and the wheel high frequency dynamic vibration absorber (16) damping c d , and obtain the optimal parameters.

2. The parameter design method according to claim 1, characterized in that: The elastic element is a coaxial rubber spring (17), and the mass block is a coaxial mass block (18). The coaxial rubber spring (17) and the coaxial mass block (18) are both sleeved on the outside of the oil cylinder and the plunger rod with a gap. The lower end of the coaxial rubber spring (17) is fixedly connected to the third connecting device (15), and the upper end is fixedly connected to the coaxial mass block (18). The coaxial rubber spring (17) and the coaxial mass block (18) do not contact the oil cylinder and the vehicle body when the suspension is working. The coaxial rubber spring (17) provides the stiffness and damping required for the wheel high-frequency dynamic vibration absorber (16) to work.

3. The parameter design method according to claim 1, wherein: The elastic element is a heteroaxial rubber spring (19), and the mass block is a heteroaxial mass block (20). The lower end of the heteroaxial rubber spring (19) is fixedly connected to the third connecting device (15), and the upper end is fixedly connected to the heteroaxial mass block (20). The heteroaxial mass block (20) and the heteroaxial rubber spring (19) are parallel to the central axis of the oil cylinder and the plunger rod, but not collinear. When the suspension is working, the heteroaxial rubber spring (19) and the heteroaxial mass block (20) are not in contact with the oil cylinder and the vehicle body. The heteroaxial rubber spring (19) provides the stiffness and damping required for the wheel high-frequency dynamic vibration absorber (16) to work.

4. The parameter design method according to claim 1, wherein: The elastic element is a coil spring (21), the mass block is a non-coaxial mass block (20), the coil spring (21) is sleeved on the outside of the shock absorber (22), the lower ends of the coil spring (21) and the shock absorber (22) are fixedly connected to the third coupling device (15), and the upper ends are fixedly connected to the non-coaxial mass block (20), the coil spring (21), the shock absorber (22) and the non-coaxial mass block (20) are parallel to the central axis of the oil cylinder and the plunger rod, but not collinear, and when the suspension is working, the coil spring (21) and the non-coaxial mass block (20) do not contact the oil cylinder and the vehicle body.

5. The parameter design method according to claim 1, wherein: The optimization objective function G q0 is the road roughness coefficient, u is the vehicle speed, f 2c The value is determined to be between 1 and 1.2 according to the ride comfort requirements of automobile design, n0 is the reference spatial frequency, and F(6,:) is the sixth row of the F matrix.

6. The parameter design method according to claim 1, wherein: The mass of the wheel high-frequency dynamic vibration absorber (16) is m d =n1m1, n1 is 0.1-0.4; the minimum stiffness of the suspension in the comfort mode k 2c =m2(2πf 2c ) 2 , the inertia tube damping c 2c The value range is The inertia tube inertia m e The value range is (0.4~3)m d The wheel high frequency dynamic vibration absorber (16) has a stiffness k d The value range is The damping c of the wheel high-frequency dynamic vibration absorber (16) d The value range is 7. The parameter design method according to claim 1, characterized in that: In step 4), a genetic algorithm is used to find the optimal parameters.

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