Air spring dynamic response estimation method and device

Abstract

The present invention provides a method and device for estimating the dynamic response of an air spring, wherein the method comprises: obtaining thermodynamic parameters of an air bag in an air spring; determining the stiffness and damping generated by the air bag based on the thermodynamic parameters, wherein the damping is the equivalent damping generated by heat exchange between the gas in the air spring and the outside gas; and determining the stiffness of the air spring based on the stiffness and damping generated by the air bag. This method is used to solve the defect that the response prediction method is not easy to apply in actual engineering because the dynamic response of the air spring needs to be predicted using parameters that are not easy to directly measure in the prior art, and the dynamic response of the air spring can be predicted using directly measured parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of air spring dynamic response prediction, and in particular to an air spring dynamic response estimation method and device. Background Art

[0002] The ride comfort and handling stability of passenger cars have always been one of the biggest demands of users. The transmission of mechanical properties between the car body and the ground mainly depends on the suspension form and the elastic and damping element characteristics. Traditional coil springs and passive shock absorbers can suppress vibrations within a certain frequency range, but they have little effect or even amplify vibrations under certain working conditions, so it is necessary to improve the suspension system for passenger cars.

[0003] The air suspension system that has emerged has improved the vibration isolation performance of the suspension to a certain extent. Relying on its excellent nonlinear stiffness characteristics, it can limit the suspension's frequency deviation within a certain range to minimize the transmission of road excitation to the vertical movement of the vehicle. Another excellent feature of the air suspension system is that it can change the height of the vehicle body to match the dynamic behavior of the vehicle to the greatest extent. For example, in order to reduce wind resistance during high-speed driving, the height of the vehicle body can be reduced to the minimum; in order to increase the vehicle's passability during off-road driving, the chassis height can be increased.

[0004] In the electronically controlled air suspension system, the most important actuator is the air spring. Therefore, it is very necessary to accurately estimate the dynamic behavior of the air spring. At present, there are mainly equivalent mechanics, geometry, thermodynamics, etc. for estimating the dynamic response of air springs, such as: "Nishimura model", "Simpackmodel" with certain frequency applicability, "Vampire model" considering the damping square term, "Berg model" considering the additional air chamber and friction damping related to the velocity exponential term, and some corresponding improved models, etc. However, these models require more parameters to be calibrated and are not easy to measure directly, such as friction terms, viscosity terms, etc., which are very difficult to apply in practice and are therefore not suitable for engineering applications. Summary of the invention

[0005] The present invention provides a method and device for estimating the dynamic response of an air spring, which are used to solve the defect in the prior art that the dynamic response of an air spring needs to be predicted using parameters that are difficult to directly measure, resulting in the response prediction method being difficult to apply in actual engineering projects, and realizes the prediction of the dynamic response of an air spring by using directly measured parameters.

[0006] The present invention also provides a method for constructing an air spring dynamic response prediction model, comprising:

[0007] Obtaining thermodynamic parameters of the air bag in the air spring;

[0008] Based on the thermodynamic parameters, determining the stiffness and damping generated by the air bag, wherein the damping is the equivalent damping generated by heat exchange between the gas in the air spring and the external gas;

[0009] Based on the stiffness and damping generated by the air bag, the stiffness of the air spring is determined.

[0010] The method for estimating the dynamic response of an air spring according to the present invention further includes:

[0011] Acquire dynamic characteristic parameters of the rubber bladder of the air spring with amplitude; the dynamic characteristic parameters include: damping of the rubber bladder under infinite amplitude, and fractal dimension correlation constants of the carbon black structure of the rubber material of the rubber bladder;

[0012] Based on the dynamic characteristic parameters, determining the damping generated by the rubber bladder skin and the effective area of ​​the air spring;

[0013] The stiffness of the air spring is determined based on the damping produced by the rubber bladder, the effective area of ​​the air spring, and the amplitude.

[0014] According to the air spring dynamic response estimation method of the present invention, the thermodynamic parameters include: the equivalent heat exchange coefficient K between the air bag and the outside world b , initial pressure p b0 , initial volume V b0 , the initial gas mass m in the air bag b0 , and the constant volume specific heat capacity C of the gas in the air bag V .

[0015] According to the air spring dynamic response estimation method of the present invention, determining the stiffness of the air spring based on the stiffness and damping generated by the air bag includes:

[0016] The stiffness of the air spring is determined based on the stiffness and damping produced by the air bag, the circular frequency of vibration, and the effective area.

[0017] According to the air spring dynamic response estimation method of the present invention, determining the stiffness and damping generated by the air bag based on the thermodynamic parameters includes:

[0018] According to a first preset formula, based on the thermodynamic parameters, the stiffness and damping generated by the air bag are determined, wherein the first preset formula includes:

[0019]

[0020]

[0021] Wherein, K1(ω) is the stiffness of the air spring; ω is the circular frequency of vibration; k1 is the stiffness generated by the air bag; c1 is the damping; j is a complex unit; γ is a polynomial index; A eff is the effective area; K b is the equivalent heat exchange coefficient between the air bag and the outside world, p b0 is the initial pressure in the air bag, V b0 is the initial volume of the air bag, m b0 is the initial mass of the gas in the air bag, C V is the constant volume specific heat capacity of the gas in the air bag.

[0022] According to the air spring dynamic response estimation method of the present invention, the first preset formula is constructed in the following manner:

[0023] Based on the first law of thermodynamics, a mass flow equation of the air bag of the air spring is established;

[0024] The mass flow equation and the dynamic equation of a quarter suspension using the air spring are combined to derive the first preset formula;

[0025] Wherein, the mass flow equation of the air spring is:

[0026]

[0027] Among them, T atm is the Calvin temperature of the outside atmosphere; T b is the Calvin temperature of the air bag; p b is the pressure of the air bag; is the volume change rate of the air bag; is the gas mass change rate in the air bag; m b is the mass of gas in the air bag; is the temperature change rate of the gas in the air bag.

[0028] According to the air spring dynamic response estimation method of the present invention, the mass flow equation and the dynamic equation of a quarter suspension using the air spring are combined to derive the first preset formula, including:

[0029] Based on the volume change rate formula and the mechanical transfer formula of the air spring, the mass flow equation and the dynamic equation are combined to obtain a primary equation for determining the stiffness and damping generated by the air bag;

[0030] The primary equation is simplified according to a preset parameter assumption relationship to obtain a secondary equation representing the corresponding relationship between the stiffness of the air spring and the pressure of the air bag and the effective area;

[0031] Substituting the travel change equation of the quarter suspension into the secondary equation to obtain the first preset formula;

[0032] The preset parameters include: the temperature difference between the Calvin temperature of the air bag and the outside atmosphere, the coupling term between the pressure of the air bag and the speed caused by the pressure of the air bag, and the travel change of the quarter suspension;

[0033] The preset parameter assumption relationship includes:

[0034]

[0035]

[0036]

[0037] Where R is the ideal gas state constant; p atm is the pressure of the outside atmosphere; z2 is the displacement of the vehicle body using the quarter suspension; z1 is the displacement of the wheel using the quarter suspension; F AS is the vertical force transmitted by the air spring; is the sprung position velocity of the quarter suspension; is the unsprung position velocity of the quarter suspension; h0 is the initial height of the air spring.

[0038] According to the air spring dynamic response estimation method of the present invention, determining the stiffness of the air spring based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude includes:

[0039] According to the second preset formula and the third preset formula, the stiffness of the air spring is determined based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude, and the second preset formula and the third preset formula are respectively:

[0040]

[0041]

[0042] Among them, c A is the stiffness of the air spring due to the rubber damping; x is the amplitude; a1 is the rubber damping under infinite amplitude; k Ais the stiffness of the air spring due to the dynamic characteristics of the rubber bag skin; a2 is the dynamic stiffness generated by the change of the effective area; b1 and b2 are correction coefficients of the amplitude; d1 and d2 are constants related to the fractal dimension.

[0043] According to the air spring dynamic response estimation method of the present invention, determining the stiffness of the air spring includes:

[0044] According to a preset fourth formula, the stiffness of the air spring is determined based on the stiffness and damping generated by the air bag, the damping generated by the rubber bag skin, the effective area of ​​the air spring, and the amplitude. The preset fourth formula includes:

[0045]

[0046] Wherein, K(ω) is the stiffness of the air spring.

[0047] The present invention also provides an air spring dynamic response estimation device, comprising:

[0048] A data acquisition module, used to obtain thermodynamic parameters of an air bag in an air spring;

[0049] A data calculation module, used for determining the stiffness and damping generated by the air bag based on the thermodynamic parameters, wherein the damping is the equivalent damping generated by heat exchange between the gas in the air spring and the external gas;

[0050] The stiffness estimation module is used to determine the stiffness of the air spring based on the stiffness and damping generated by the air bag.

[0051] The present invention provides a method and device for estimating the dynamic response of an air spring. The method determines the stiffness and damping generated by the air bag by obtaining the thermodynamic parameters of the air bag in the air spring, and then determines the stiffness of the air spring based on the stiffness and damping generated by the air bag. On the one hand, the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas is determined by the thermodynamic parameters of the air bag. That is, when estimating the dynamic response of the air spring, not only the stiffness generated by the gas movement of the air bag is considered, but also the stiffness of the air spring due to the equivalent damping generated by the heat exchange is taken into account, so that the estimation of the dynamic response of the air spring is more accurate. On the other hand, the thermodynamic parameters of the air bag are all parameters that can be directly measured by the existing air suspension test system, and the parameters are easy to obtain. Therefore, the stiffness of the air spring is determined by using the stiffness and damping generated by the air bag determined by these parameters, so that the stiffness and damping generated by the air bag are expressed by using convenient and easy-to-obtain thermodynamic parameters, making the method for estimating the dynamic response of the air spring highly feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 This is the working principle diagram of the air spring charging, deflating and mass setting;

[0054] Figure 2 This is the schematic diagram of the dynamometer test platform for air springs;

[0055] Figure 3 It is a flow chart of a method for estimating the dynamic response of an air spring provided by the present invention;

[0056] Figure 4 It is a schematic diagram of a quarter suspension;

[0057] Figure 5 It is an equivalent mechanical model using the air spring dynamic response estimation method provided by the present invention;

[0058] Figure 6 It is a comparison chart of constant amplitude test results between the estimation results of the air spring dynamic response estimation method provided by the present invention and the estimation results of other models;

[0059] Figure 7 It is a constant frequency test result comparison diagram of the estimation result of the air spring dynamic response estimation method provided by the present invention and the estimation result of other models;

[0060] Figure 8 It is a constant amplitude error comparison diagram of the estimation results of the air spring dynamic response estimation method provided by the present invention and the estimation results of other models;

[0061] Fig. 9 It is a constant frequency error comparison diagram of the estimation results of the air spring dynamic response estimation method provided by the present invention and the estimation results using other models;

[0062] Fig.10 It is a structural schematic diagram of an air spring dynamic response estimation device provided by the present invention;

[0063] Fig.11 It is a structural schematic diagram of the electronic device provided by the present invention.

[0064] Reference numerals:

[0065] 1: air bag; 2: additional air chamber; 3: piston;

[0066] 4: Gas tank; 5: Pipeline; 6: Solenoid valve. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] First, to facilitate the understanding of the prediction method of the invention, the air spring involved in the invention is first introduced. It should be noted that the technical solution of the invention is aimed at a rubber air spring for a passenger car.

[0069] The rubber air spring is a flexible body formed by vulcanization of the cord layer and the inner and outer rubber layers after molding. It is a rubber element that uses the compressibility of the filled air to achieve elastic function. It is commonly known as air spring, rubber airbag, airbag, etc.

[0070] like Figure 1 As shown in the figure, it is a working principle diagram of the air spring for charging and discharging and determining the mass. The air spring mainly includes: an air bag 1 for the main bearing capacity, an additional air chamber 2 for adjusting the stiffness, a piston 3, an air storage tank 4 for charging, and related pipelines 5 and other parts, wherein a solenoid valve 6 for controlling charging and discharging needs to be set on the pipeline 5. It can be understood that after the charging and discharging are completed, the mass of the gas inside the air spring is determined.

[0071] Next, the commonly used dynamometer test platform used in the present invention is introduced. The principle of the dynamometer test platform is as follows: Figure 2 As shown, in the embodiment of the present invention, the connecting pipeline is connected by a 5mm pipeline, and then the air spring is inflated by a high-pressure gas source. After reaching the working force value, the pressure is controlled by a pressure reducing valve. After that, the pressure value at this time is read and the pipe length is constrained for testing. The test data is read by the MTS sensor, and various data about the air spring can be obtained, such as: the force sensor value of a fixed sampling frequency, the displacement of the hydraulic actuator, the actuator speed, the recording time, etc. The obtained test initial state data is shown in Table 1:

[0072] Table 1 Initial state of the test

[0073] Parameter / Unit Value Parameter / Unit Value <![CDATA[T0 / (K)]]> 298 <![CDATA[K b / (J / K)]]> 1.039 <![CDATA[A eff / (m 2 )]]> 0.01079 <![CDATA[z0 / (m)]]> 0.1303 <![CDATA[p b0 / (N / m 2 )]]> <![CDATA[9×10 5 ]]> <h2 style=";text-align:left;direction:ltr"><![CDATA[C <h2 style=";text-align:left;direction:ltr"> V <h2 style=";text-align:left;direction:ltr"> / (J / (K·kg))]]><h2 style=";text-align:left;direction:ltr"> 717.5 <![CDATA[V b0 / (m 3 )]]> <![CDATA[2.45×10 -3 ]]> κ / (1 / m) 6.6061 <![CDATA[m b0 / (kg)]]> 0.02578 A / (m) 0.026

[0074] Again, the parameters and positive directions involved in the present invention are defined: m, p, V, T represent mass, pressure, volume and Calvin temperature respectively, and the subscripts b, atm represent the air bag and the outside atmosphere. R is the ideal gas state constant, and γ is the polynomial index. The pressure is absolute pressure; the change in gas pressure, temperature, mass, and volume is positive as it increases; displacement and force are positive in the upward direction. The gas state equation and its total differential are always valid, and the first law of thermodynamics is always valid, with heat absorption from the outside, work done by the outside on the gas, and increase in internal energy as positive. At the same time, it is assumed that the tube connecting the additional air chamber and the air bag is very short and has no mass lag.

[0075] Combine the following Figure 3-Figure 9 A method for estimating the dynamic response of an air spring according to the present invention is described, and the method is executed by a computer or a combination of software and / or hardware therein, such as Figure 3 As shown, the method comprises the following steps:

[0076] 101. Obtain the thermodynamic parameters of the air bag in the air spring.

[0077] Specifically, thermodynamic parameters are basic quantities used to describe the state of matter, such as temperature, pressure, specific volume, enthalpy, entropy, etc. Among them, the three basic parameters in thermodynamics are pressure, volume and temperature. In the embodiment of the present invention, the thermodynamic parameters of the air bag in the air spring are obtained, that is, the parameters characterizing the pressure, temperature, specific volume, etc. of the gas in the air bag. It can be understood that these parameters can be measured very conveniently in actual engineering applications.

[0078] 102. Based on the thermodynamic parameters, determine the stiffness and damping generated by the air bag, where the damping is the equivalent damping generated by heat exchange between the gas in the air spring and the external gas.

[0079] 103. Determine the stiffness of the air spring based on the stiffness and damping generated by the air bag.

[0080] Specifically, the stiffness and damping generated by the air bag are determined by acquiring the thermodynamic parameters of the air bag in the air spring, and then the stiffness of the air spring is determined based on the stiffness and damping generated by the air bag, thereby realizing the determination of the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas through the thermodynamic parameters of the air bag. That is, when estimating the dynamic response of the air spring, not only the stiffness generated by the gas movement of the air bag is considered, but also the stiffness of the air spring due to the equivalent damping generated by the heat exchange is taken into account, which makes the estimation of the dynamic response of the air spring more accurate.

[0081] More specifically, the thermodynamic parameters of the airbag can be determined by Figure 2The parameters directly measured by the dynamometer test platform shown are easy to obtain. Therefore, the stiffness of the air spring is determined by using the stiffness and damping generated by the air bag determined by these parameters, thereby realizing the expression of the stiffness and damping generated by the air bag using convenient and easily available thermodynamic parameters, making the air spring dynamic response estimation method highly feasible.

[0082] As an embodiment of the present invention, the air spring dynamic response estimation method further includes:

[0083] Acquire dynamic characteristic parameters of the rubber bladder of the air spring with amplitude; the dynamic characteristic parameters include: damping of the rubber bladder under infinite amplitude, and fractal dimension correlation constants of the carbon black structure of the rubber material of the rubber bladder;

[0084] Based on the dynamic characteristic parameters, determining the damping generated by the rubber bladder skin and the effective area of ​​the air spring;

[0085] The stiffness of the air spring is determined based on the damping produced by the rubber bladder, the effective area of ​​the air spring, and the amplitude.

[0086] It is understandable that for an air spring composed of a rubber bladder, the flexible structure of the rubber bladder should also make a certain contribution to the stiffness of the air spring. At the same time, the effective area of ​​the air spring can transfer the air pressure in the air spring to the surface of the part in contact with it in the form of force. Therefore, the deformation of the rubber bladder is also related to the change in the effective area. Therefore, in order to further improve the accuracy of the estimation of the dynamic response of the air spring, the influence of the rubber bladder on the stiffness of the air spring should also be taken into account.

[0087] Specifically, the damping generated by the rubber bladder and the effective area of ​​the air spring are directly related to the material of the rubber bladder. Therefore, in the above embodiment of the present invention, the dynamic characteristic parameters include the damping of the rubber bladder under infinite amplitude and the fractal dimension related constants of the carbon black structure of the rubber material of the rubber bladder.

[0088] Furthermore, considering that the stiffness of the air spring caused by the change in the effective area and the damping generated by the rubber bladder should be related to the amplitude of the excitation source that excites the air spring, according to the dynamic characteristics of the rubber material, in the above embodiment of the present invention, the damping generated by the rubber bladder and the effective area of ​​the air spring are determined by obtaining the dynamic characteristics of the rubber bladder of the air spring with the amplitude, and then the stiffness of the air spring is determined based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude, thereby further improving the accuracy of the estimation of the dynamic response of the air spring.

[0089] As an embodiment of the present invention, the thermodynamic parameters include: the equivalent heat exchange coefficient K between the air bag and the outside world b , initial pressure p b0 , initial volume V b0 , the initial gas mass m in the air bag b0 , and the constant volume specific heat capacity C of the gas in the air bag V .

[0090] Specifically, as shown in Table 1, the equivalent heat exchange coefficient K between the air bag and the outside world is b , initial pressure p b0 , initial volume V bx 、The initial gas mass in the air bag m b0 , and the constant volume specific heat capacity C of the gas in the air bag V , these parameters can be directly measured through the existing dynamometer test platform.

[0091] As an embodiment of the present invention, determining the stiffness of the air spring based on the stiffness and damping generated by the air bag includes:

[0092] The stiffness of the air spring is determined based on the stiffness and damping produced by the air bag, the circular frequency of vibration, and the effective area.

[0093] As an embodiment of the present invention, determining the stiffness and damping generated by the air bag based on the thermodynamic parameters includes:

[0094] According to a first preset formula, based on the thermodynamic parameters, the stiffness and damping generated by the air bag are determined, wherein the first preset formula includes:

[0095]

[0096]

[0097] Wherein, K1(ω) is the stiffness of the air spring; ω is the circular frequency of vibration; k1 is the stiffness generated by the air bag; c1 is the damping; j is a complex unit; γ is a polynomial index; A eff is the effective area; K b is the equivalent heat exchange coefficient between the air bag and the outside world, p b0 is the initial pressure in the air bag, V b0 is the initial volume of the air bag, m b0 is the initial mass of the gas in the air bag, C V is the constant volume specific heat capacity of the gas in the air bag.

[0098] Specifically, it can be seen from the formula shown in the embodiment of the present invention that the parameters involved in the formula can be obtained by Figure 2 The dynamometer test platform shown in the figure is obtained, which facilitates the application of the prediction model in actual engineering. At the same time, according to the formula of c1, the equivalent heat exchange coefficient K between the air bag and the outside world is b This is mainly caused by the heat exchange between the rubber bladder and the high-pressure gas in the air spring and the outside world.

[0099] As an embodiment of the present invention, the first preset formula is constructed in the following manner:

[0100] Based on the first law of thermodynamics, a mass flow equation of the air bag of the air spring is established;

[0101] The mass flow equation and the dynamic equation of a quarter suspension using the air spring are combined to derive the first preset formula;

[0102] Wherein, the mass flow equation of the air spring is:

[0103]

[0104] Among them, T atm is the Calvin temperature of the outside atmosphere; Tb is the Calvin temperature of the air bag; p b is the pressure of the air bag; is the volume change rate of the air bag; is the gas mass change rate in the air bag; m b is the mass of gas in the air bag; is the temperature change rate of the gas in the air bag.

[0105] Among them, the schematic diagram of the quarter suspension is as follows Figure 4 As shown, the quarter suspension dynamic equation is:

[0106]

[0107] It can be understood that the parameters involved in the quarter suspension dynamics equation include: m1 and m2 representing the unsprung mass and sprung mass of the air spring respectively; z1 representing the displacement of the wheel using the quarter suspension; p representing the pressure of the air bag and the pressure of the outside atmosphere respectively; b and p atm , and A representing the effective area of ​​the air spring eff , etc. These parameters can be measured directly or indirectly through the air spring dynamometer test platform and the quarter suspension test.

[0108] Specifically, based on the first law of thermodynamics, a mass flow equation for the air bag of the air spring is established, and then the mass flow equation is combined with the dynamic equation of the quarter suspension to derive a formula for determining the stiffness and damping generated by the air bag. The parameters constituting the mass flow equation and the dynamic equation of the quarter suspension are all parameters that can be directly measured by the dynamic response test platform of the air spring, thereby achieving the expression of the stiffness and damping generated by the air bag of the air spring through parameters that can be directly measured, so that the parameters used for estimating the dynamic response of the air spring are easy to obtain and are convenient for application in actual engineering. At the same time, the estimation of the dynamic response of the air spring through parameter calculation does not constrain the gas change process in the air spring, and has strong universality.

[0109] More specifically, the mass flow equation of the air spring shown in this embodiment is a differential expression of the mass flow obtained by eliminating the temperature derivative with time from the mass flow equation written based on the first law of thermodynamics using the ideal gas state equation. As mentioned above, the parameters involved in the differential expression of the mass flow can be obtained by Figure 2 The dynamometer test platform shown is obtained directly or indirectly, therefore, by combining the mass flow equation and the quarter suspension dynamics equation, the derived relationship equation containing the correspondence between the dynamic stiffness and damping of the air spring can be fully expressed by utilizing the parameters directly obtained from the existing test platform, thereby providing an accurate mathematical expression for the estimation of the dynamic response of the air spring, and the estimation method only needs to indirectly identify a small number of parameters in combination with the direct measurement values ​​and test results of the test, which is highly feasible.

[0110] As an embodiment of the present invention, the mass flow equation and the dynamic equation of a quarter suspension using the air spring are combined to derive the first preset formula, including:

[0111] Based on the volume change rate formula and the mechanical transfer formula of the air spring, the mass flow equation and the dynamic equation are combined to obtain a primary equation for determining the stiffness and damping generated by the air bag;

[0112] The primary equation is simplified according to a preset parameter assumption relationship to obtain a secondary equation representing the corresponding relationship between the stiffness of the air spring and the pressure of the air bag and the effective area;

[0113] Substituting the travel change equation of the quarter suspension into the secondary equation to obtain the first preset formula;

[0114] The preset parameters include: the temperature difference between the Calvin temperature of the air bag and the outside atmosphere, the coupling term between the pressure of the air bag and the speed caused by the pressure of the air bag, and the travel change of the quarter suspension;

[0115] The preset parameter assumption relationship includes:

[0116]

[0117]

[0118]

[0119] Where R is the ideal gas state constant; subscript 0 represents the initial state; p atm is the pressure of the outside atmosphere; z2 is the displacement of the vehicle body using the quarter suspension; z1 is the displacement of the wheel using the quarter suspension; F AS is the vertical force transmitted by the air spring; is the sprung position velocity of the quarter suspension; is the unsprung position velocity of the quarter suspension; h0 is the initial height of the air spring.

[0120] It can be understood that the above parameter assumptions are all made without changing the essence of aerodynamics.

[0121] Specifically, the volume change rate formula and the mechanical transmission formula of the air spring are:

[0122]

[0123] F AS =(p b -p atm )A eff (9);

[0124] It can be seen that the volume change rate and the transmitted force are respectively related to the sprung position velocity of the quarter suspension and unsprung position speed and p, which represent the pressure of the air bag and the pressure of the outside atmosphere respectively. b and p atm Therefore, the above two equations can be used to transform some parameters of the simultaneous equations of the mass flow equation and the kinetic equation, so that the equations can be preliminarily simplified.

[0125] Then, without changing the essence of aerodynamics, the assumed relationship between the preset parameters can be used to further simplify the primary equation through mathematical techniques, and the simplified secondary equation can be used as an expression of the contribution of the two parts of the effective area change and the pressure change to the stiffness.

[0126] Furthermore, the secondary equation is subjected to Fourier transformation, and then the Fourier transform of one quarter of the suspension dynamic travel Z(ω)=Z1(ω)-z2(ω) is substituted into it to obtain the relationship equation.

[0127] As an embodiment of the present invention, determining the stiffness of the air spring based on the damping generated by the rubber bladder, the effective area of ​​the air spring, and the amplitude includes:

[0128] According to the second preset formula and the third preset formula, the stiffness of the air spring is determined based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude, and the second preset formula and the third preset formula are respectively:

[0129]

[0130]

[0131] Among them, c A is the stiffness of the air spring due to the rubber damping; x is the amplitude; a1 is the rubber damping under infinite amplitude; k A is the stiffness of the air spring due to the dynamic characteristics of the rubber bag skin; a2 is the dynamic stiffness generated by the change of the effective area; b1 and b2 are correction coefficients of the amplitude; d1 and d2 are constants related to the fractal dimension.

[0132] Specifically, the dynamic stiffness of the air spring due to the rubber damping should also be related to the rubber material itself. Therefore, in the above-mentioned embodiment of the present invention, the dynamic stiffness of the air spring due to the rubber damping is expressed as rubber damping, amplitude, amplitude correction coefficient, and a relationship related to the fractal dimension correlation constant of the carbon black structure of the rubber material used to manufacture the rubber bladder skin.

[0133] At the same time, considering that the dynamic stiffness of the air spring caused by the change in the effective area should be related to the amplitude of the excitation source that excites the air spring, according to the dynamic characteristics of the rubber material, in the above-mentioned embodiment of the present invention, the dynamic stiffness of the air spring caused by the dynamic characteristics of the rubber bladder skin is expressed as a relationship related to the dynamic stiffness caused by the change in the effective area, the amplitude, the correction coefficient of the amplitude, and a constant related to the fractal dimension of the carbon black structure of the rubber material used to manufacture the rubber bladder skin.

[0134] Based on the above embodiment, as an embodiment of the present invention, determining the stiffness of the air spring includes:

[0135] According to a preset fourth formula, the stiffness of the air spring is determined based on the stiffness and damping generated by the air bag, the damping generated by the rubber bag skin, the effective area of ​​the air spring, and the amplitude. The preset fourth formula includes:

[0136]

[0137] Wherein, K(ω) is the stiffness of the air spring.

[0138] Specifically, the equivalent mechanical model of the air spring dynamic response estimation method is as follows: Figure 5 As shown in the figure, the dynamic stiffness and rubber damping changes caused by the change in effective area are k A , c A , and the dynamic stiffness and damping terms generated by the air bag part are k1 and c1, and the two parts are connected in series to form the estimated value of the dynamic response of the air spring obtained by the air spring dynamic response estimation method described in the present invention. It can be seen that the dynamic response of the air spring is estimated by the air spring dynamic response estimation method described in the present invention, and the dynamic response estimation of the air spring is formed into a nonlinear expression that comprehensively considers the equivalent damping characteristics generated by external heat exchange, the air cavity stiffness characteristics of the air bag, and the air bag damping characteristics, and gives a clear physical meaning and precise mathematical expression of each contribution term, which solves the problem of how to express the equivalent damping characteristics generated by heat exchange between gas and additional air chambers, the contribution of the bag rubber to stiffness, and the nonlinear change of dynamic stiffness with amplitude.

[0139] The accuracy of the air spring dynamic response estimation method described in the present invention is verified below. The exact solution considering the hysteresis characteristics proposed in the present invention is simulated using Simulink and compared with the experiment. The results are as follows: Figure 6 and Figure 7 As shown. It can be seen that the linear stiffness formula can fit the dynamic behavior of the air spring well within a certain small vibration amplitude range (about ±5mm), but the fitting effect gradually deteriorates as the amplitude increases. The nonlinear stiffness formula can describe the dynamic behavior of the air spring within a larger amplitude range, but its disadvantage is that it cannot reflect the hysteresis characteristics of the air spring loading and unloading.

[0140] It is understandable that the hysteresis characteristics of the air spring may be very serious under different designs or working conditions. Here, the difference between loading and unloading in the test value near the initial coordinate range is about 150 N. From the precise solution curve considering the heat exchange and rubber damping of the air spring proposed in the above embodiment of the present invention, it can be seen that the prediction model described in the present invention can accurately describe the hysteresis characteristics and dynamic behavior of the air spring during movement, and is highly consistent with the experiment.

[0141] Specifically, different theoretical formulas are compared with test results, and the error between the prediction model of the present invention and other models in predicting the dynamic response of the same air spring is considered by providing a calculation formula for the error quantification index.

[0142] Furthermore, the theoretical values ​​of different models F model With the test value F 2xp The absolute value of the relative error is calculated as:

[0143]

[0144] The error comparison of different models obtained by the above calculation formula is as follows: Figure 8 and Fig. 9 As shown, it can be seen that the linear model has the largest error, and the prediction error exceeds 3% at the maximum amplitude; the nonlinear model has higher accuracy than the linear model, and the error is larger in the middle position and smaller at the maximum amplitude; the prediction model described in the present invention gives the highest accuracy of the exact solution, and its relative error can be controlled within 0.5% regardless of the displacement size. Therefore, it can be concluded that the analytical calculation formula for the dynamic stiffness of the multi-chamber air spring proposed in this paper has high accuracy and can be applied to the precise control and forward development of air suspension.

[0145] Combine the following Fig.10 An air spring dynamic response estimation device provided by the present invention is described. The air spring dynamic response estimation device described below and the air spring dynamic response estimation method described above can correspond to each other.

[0146] like Fig.10 As shown, a device for constructing a dynamic response prediction model of an air spring provided by the present invention includes: a data acquisition module 100, a data calculation module 110 and a stiffness estimation module 120; wherein,

[0147] The data acquisition module 100 is used to acquire thermodynamic parameters of the air bag in the air spring;

[0148] The data calculation module 110 is used to determine the stiffness and damping generated by the air bag based on the thermodynamic parameters, wherein the damping is the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas;

[0149] The stiffness estimation module 120 is used to determine the stiffness of the air spring based on the stiffness and damping generated by the air bag.

[0150] Specifically, the air spring dynamic response estimation device determines the stiffness and damping generated by the air bag by acquiring the thermodynamic parameters of the air bag in the air spring, and then determines the stiffness of the air spring based on the stiffness and damping generated by the air bag. On the one hand, it realizes the determination of the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas through the thermodynamic parameters of the air bag, that is, when estimating the dynamic response of the air spring, not only the stiffness generated by the gas movement of the air bag is considered, but also the stiffness of the air spring due to the equivalent damping generated by the heat exchange, so that the estimation of the dynamic response of the air spring is more accurate. On the other hand, the thermodynamic parameters of the air bag can be obtained by Figure 2 The parameters directly measured by the dynamometer test platform shown are easy to obtain. Therefore, the stiffness of the air spring is determined by using the stiffness and damping generated by the air bag determined by these parameters, thereby realizing the expression of the stiffness and damping generated by the air bag using convenient and easily available thermodynamic parameters, making the air spring dynamic response estimation method highly feasible.

[0151] Fig.11 An example of a physical structure diagram of an electronic device is shown in FIG. Fig.11 As shown, the electronic device may include: a processor 111, a communication interface 112, a memory 113 and a communication bus 114, wherein the processor 111, the communication interface 112 and the memory 113 communicate with each other through the communication bus 114. The processor 111 may call the logic instructions in the memory 113 to execute the air spring dynamic response estimation method, the method comprising: obtaining the thermodynamic parameters of the air bag in the air spring; based on the thermodynamic parameters, determining the stiffness and damping generated by the air bag, the damping being the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas; based on the stiffness and damping generated by the air bag, determining the stiffness of the air spring.

[0152] In addition, the logic instructions in the above-mentioned memory 113 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0153] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the air spring dynamic response estimation method provided by the above-mentioned methods, and the method includes: obtaining the thermodynamic parameters of the air bag in the air spring; based on the thermodynamic parameters, determining the stiffness and damping generated by the air bag, the damping is the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas; based on the stiffness and damping generated by the air bag, determining the stiffness of the air spring.

[0154] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the air spring dynamic response estimation method provided by the above-mentioned methods is implemented, and the method includes: obtaining the thermodynamic parameters of the air bag in the air spring; based on the thermodynamic parameters, determining the stiffness and damping generated by the air bag, the damping is the equivalent damping generated by the heat exchange between the gas in the air spring and the external gas; based on the stiffness and damping generated by the air bag, determining the stiffness of the air spring.

[0155] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0156] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for estimating the dynamic response of an air spring, characterized in that: include: Obtaining thermodynamic parameters of the air bag in the air spring; Based on the thermodynamic parameters, determining the stiffness and damping generated by the air bag, wherein the damping is the equivalent damping generated by heat exchange between the gas in the air spring and the external gas; Determining the stiffness of the air spring based on the stiffness and damping generated by the air bag; and further comprising: Acquire dynamic characteristic parameters of the rubber bladder of the air spring with amplitude; the dynamic characteristic parameters include: damping of the rubber bladder under infinite amplitude, and fractal dimension correlation constants of the carbon black structure of the rubber material of the rubber bladder; Based on the dynamic characteristic parameters, determining the damping generated by the rubber bladder skin and the effective area of ​​the air spring; determining the stiffness of the air spring based on the damping generated by the rubber bladder, the effective area of ​​the air spring, and the amplitude; The determining of the stiffness of the air spring based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude includes: According to the second preset formula and the third preset formula, the stiffness of the air spring is determined based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude, and the second preset formula and the third preset formula are respectively: Among them, c A is the stiffness of the air spring due to the rubber damping; x is the amplitude; a1 is the rubber damping under infinite amplitude; k A is the stiffness of the air spring due to the dynamic characteristics of the rubber bag skin; a2 is the dynamic stiffness generated by the change of the effective area; b1 and b2 are correction coefficients of the amplitude; d1 and d2 are constants related to the fractal dimension; Determining the stiffness of the air spring includes: According to a preset fourth formula, the stiffness of the air spring is determined based on the stiffness and damping generated by the air bag, the damping generated by the rubber bag skin, the effective area of ​​the air spring, and the amplitude. The preset fourth formula includes: Wherein, K(ω) is the stiffness of the air spring.

2. The air spring dynamic response estimation method according to claim 1, characterized in that: The thermodynamic parameters include: the equivalent heat exchange coefficient K between the air bag and the outside world b , initial pressure p b0 , initial volume V b0 , the initial gas mass m in the air bag b0 , and the constant volume specific heat capacity C of the gas in the air bag V .

3. The air spring dynamic response estimation method according to claim 2, characterized in that: Determining the stiffness of the air spring based on the stiffness and damping generated by the air bag includes: The stiffness of the air spring is determined based on the stiffness and damping produced by the air bag, the circular frequency of vibration, and the effective area.

4. The air spring dynamic response estimation method according to claim 3, characterized in that: The step of determining the stiffness and damping generated by the air bag based on the thermodynamic parameters comprises: According to a first preset formula, based on the thermodynamic parameters, the stiffness and damping generated by the air bag are determined, wherein the first preset formula includes: Wherein, K1(ω) is the stiffness of the air spring; ω is the circular frequency of vibration; k1 is the stiffness generated by the air bag; c1 is the damping; j is a complex unit; γ is a polynomial index; A eff is the effective area; K b is the equivalent heat exchange coefficient between the air bag and the outside world, p b0 is the initial pressure in the air bag, V b0 is the initial volume of the air bag, m b0 is the initial mass of the gas in the air bag, C V is the constant volume specific heat capacity of the gas in the air bag.

5. The air spring dynamic response estimation method according to claim 4, characterized in that: The first preset formula is constructed in the following manner: Based on the first law of thermodynamics, a mass flow equation of the air bag of the air spring is established; The mass flow equation and the dynamic equation of a quarter suspension using the air spring are combined to derive the first preset formula; Wherein, the mass flow equation of the air spring is: Among them, T atm is the Calvin temperature of the outside atmosphere; T b is the Calvin temperature of the air bag; p b is the pressure of the air bag; is the volume change rate of the air bag; is the gas mass change rate in the air bag; m b is the mass of gas in the air bag; is the temperature change rate of the gas in the air bag.

6. The air spring dynamic response estimation method according to claim 5, characterized in that: The method of deriving the first preset formula by combining the mass flow equation with the dynamic equation of the quarter suspension using the air spring includes: Based on the volume change rate formula and the mechanical transfer formula of the air spring, the mass flow equation and the dynamic equation are combined to obtain a primary equation for determining the stiffness and damping generated by the air bag; The primary equation is simplified according to a preset parameter assumption relationship to obtain a secondary equation representing the corresponding relationship between the stiffness of the air spring and the pressure of the air bag and the effective area; Substituting the travel change equation of the quarter suspension into the secondary equation to obtain the first preset formula; The preset parameters include: the temperature difference between the Calvin temperature of the air bag and the outside atmosphere, the coupling term between the pressure of the air bag and the speed caused by the pressure of the air bag, and the travel change of the quarter suspension; The preset parameter assumption relationship includes: Where R is the ideal gas state constant; p atm is the pressure of the outside atmosphere; z2 is the displacement of the vehicle body using the quarter suspension; z1 is the displacement of the wheel using the quarter suspension; F AS is the vertical force transmitted by the air spring; is the sprung position velocity of the quarter suspension; is the unsprung position velocity of the quarter suspension; h0 is the initial height of the air spring.

7. An air spring dynamic response estimation device, characterized in that: include: A data acquisition module, used to obtain thermodynamic parameters of an air bag in an air spring; A data calculation module, used to determine the stiffness and damping generated by the air bag based on the thermodynamic parameters, wherein the damping is the equivalent damping generated by heat exchange between the gas in the air spring and the external gas; a stiffness estimation module, configured to determine the stiffness of the air spring based on the stiffness and damping generated by the air bag; The stiffness estimation module is further used for: Acquire dynamic characteristic parameters of the rubber bladder of the air spring with amplitude; the dynamic characteristic parameters include: damping of the rubber bladder under infinite amplitude, and fractal dimension correlation constants of the carbon black structure of the rubber material of the rubber bladder; Based on the dynamic characteristic parameters, determining the damping generated by the rubber bladder skin and the effective area of ​​the air spring; determining the stiffness of the air spring based on the damping generated by the rubber bladder, the effective area of ​​the air spring, and the amplitude; The determining of the stiffness of the air spring based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude includes: According to the second preset formula and the third preset formula, the stiffness of the air spring is determined based on the damping generated by the rubber bladder, the effective area of ​​the air spring and the amplitude, and the second preset formula and the third preset formula are respectively: Among them, c A is the stiffness of the air spring due to the rubber damping; x is the amplitude; a1 is the rubber damping under infinite amplitude; k A is the stiffness of the air spring due to the dynamic characteristics of the rubber bag skin; a2 is the dynamic stiffness generated by the change of the effective area; b1 and b2 are correction coefficients of the amplitude; d1 and d2 are constants related to the fractal dimension; Determining the stiffness of the air spring includes: According to a preset fourth formula, the stiffness of the air spring is determined based on the stiffness and damping generated by the air bag, the damping generated by the rubber bag skin, the effective area of ​​the air spring, and the amplitude. The preset fourth formula includes: Wherein, K(ω) is the stiffness of the air spring.

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