A method and system for predicting abnormal noise of vehicle shock absorber

Abstract

The present application relates to a method and system for predicting abnormal noise of a vehicle shock absorber, and relates to the field of vehicle design technology. The method for predicting abnormal noise of a vehicle shock absorber comprises the following steps: testing to obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle; simulating to obtain the upper support dynamic stiffness of the shock absorber to be tested; simulating to obtain the noise transfer function of the shock absorber to be tested; and calculating and obtaining the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient. The present application obtains the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness and the noise transfer function of the shock absorber to be tested through testing, and based on this, predicts the abnormal noise volume corresponding to the shock absorber to be tested through calculation, thereby predicting the noise level of the shock absorber, and providing data basis for later design optimization.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle design, and in particular to a method and system for predicting abnormal noise of a vehicle shock absorber. Background Art

[0002] Abnormal noise development is an important part of vehicle quality improvement and one of the key development investments of major manufacturers. Chassis abnormal noise accounts for a large proportion of vehicle abnormal noise development work, among which the problem of shock absorber abnormal noise is particularly prominent. The shock absorber abnormal noise problem is greatly affected by the road surface and has a significant relationship with the ambient temperature. During the reversing process of the shock absorber pulling and compressing, impact vibration will be generated, which will in turn stimulate the body to generate noise. In severe cases, abnormal noise will be generated, affecting the comfort inside the vehicle.

[0003] At present, the identification of abnormal noise of shock absorbers is mainly based on vehicle road tests for evaluation, but this method can only be carried out after the prototype vehicle is manufactured, resulting in a short shock absorber development cycle, high risk after problems occur, and difficulty in improvement. In addition, relevant researchers can also identify the risk of abnormal noise based on bench tests, but they cannot consider the impact of matching with the entire vehicle.

[0004] In view of the above-mentioned deficiencies in the existing technical status, a new vehicle shock absorber abnormal noise prediction technology is now provided to meet the needs. Summary of the invention

[0005] The present application provides a method and system for predicting abnormal noise of a vehicle shock absorber. The vibration acceleration of the upper end of the piston rod of the shock absorber to be tested, the dynamic stiffness of the upper support and the noise transfer function are obtained through testing. Based on this, the volume of abnormal noise corresponding to the shock absorber to be tested is predicted through calculation, thereby predicting the noise level of the shock absorber, providing a data basis for later design optimization.

[0006] In a first aspect, the present application provides a method for predicting abnormal noise of a vehicle shock absorber, the method comprising the following steps:

[0007] The test obtains the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle;

[0008] Simulating and obtaining the dynamic stiffness of the upper support of the shock absorber to be tested;

[0009] Simulating and obtaining the noise transfer function of the shock absorber to be tested;

[0010] Based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated.

[0011] This application obtains the vibration acceleration of the upper end of the piston rod of the shock absorber, the dynamic stiffness of the upper support and the noise transfer function through testing. Based on this, the abnormal noise volume corresponding to the shock absorber to be tested is predicted by calculation, thereby predicting the noise level of the shock absorber and providing data basis for subsequent design optimization.

[0012] In addition, by testing the displacement output of the shock absorber, the rubber dynamic stiffness of the shock absorber and the vehicle body, and the vehicle body noise transfer function as the basis, the level of shock absorber noise can be predicted, and targeted optimization can be performed on the frequencies that exceed the target values. Relying on this solution, the risk of abnormal noise under the vehicle loading conditions can be comprehensively considered during the shock absorber development stage, thus advancing the development work and shortening the development cycle.

[0013] Specifically, the test for obtaining the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle includes the following steps:

[0014] Installing the shock absorber to be tested on a preset shock absorber abnormal noise test stand;

[0015] A vibration exciter is connected to the lower end of the shock absorber to be tested, and a vibration sensor is arranged at the upper end of the shock absorber to be tested;

[0016] Based on the vibration exciter and the vibration sensor, testing the vibration response level of the shock absorber under different excitation inputs;

[0017] Based on the vibration response level of the shock absorber under different excitation inputs, the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested is obtained.

[0018] Specifically, the simulation to obtain the upper support dynamic stiffness of the shock absorber to be tested includes the following steps:

[0019] Based on the body parameters of the target vehicle and the performance parameters of the piston rod connected to the shock absorber, a simulation is performed to obtain the dynamic stiffness of the upper support of the shock absorber to be tested.

[0020] Specifically, the simulation to obtain the noise transfer function of the shock absorber to be tested includes the following steps:

[0021] Establishing a whole vehicle finite element structural model and a cavity model of the target vehicle;

[0022] The noise transfer function of the shock absorber to be tested at the corresponding installation point is obtained by processing.

[0023] Specifically, the step of calculating the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient includes the following steps:

[0024] Performing Fourier transformation on the vibration acceleration of the upper end of the piston rod to obtain the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum;

[0025] Performing high-pass filtering on the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum, and performing secondary integration on the result after the high-pass filtering to obtain the corresponding displacement parameter in the frequency domain;

[0026] Based on the frequency domain lower displacement parameter, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated and obtained.

[0027] Specifically, the size of the abnormal noise in the car can be analyzed using the following abnormal noise calculation formula:

[0028] S=20lg((∫∫a(ω))K d (ω))+NTF(ω)+K(ω);

[0029] In the above formula, a(ω) is the vibration acceleration of the upper end of the piston rod of the shock absorber;

[0030] K d (ω) is the upper support dynamic stiffness of the shock absorber;

[0031] NTF(ω) is the noise transfer function from the mounting point corresponding to the shock absorber to the interior of the vehicle;

[0032] K(ω) is the first correction coefficient, which can correct the data error through empirical data accumulation;

[0033] In the above symbols, ω indicates that frequency domain representation is used.

[0034] Furthermore, after calculating the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, the method further includes the following steps:

[0035] Comparing the abnormal noise volume corresponding to the shock absorber to be tested with a preset abnormal noise volume threshold;

[0036] When the abnormal noise volume is greater than the abnormal noise volume threshold, a structural optimization warning is generated.

[0037] In a second aspect, the present application provides a vehicle shock absorber abnormal noise prediction system, the system comprising:

[0038] A first testing device, which is used to test and obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle;

[0039] A second testing device, which is used to simulate and obtain the upper support dynamic stiffness of the shock absorber to be tested;

[0040] A third testing device, which is used to simulate and obtain the noise transfer function of the shock absorber to be tested;

[0041] A noise calculation device is used to calculate the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient.

[0042] Specifically, the first testing device includes:

[0043] A shock absorber abnormal noise test stand for mounting the shock absorber to be tested;

[0044] A vibration exciter connected to the lower end of the shock absorber to be tested;

[0045] A vibration sensor is used to be connected to the upper end of the shock absorber to be tested.

[0046] Specifically, the second testing device is used to perform simulation based on the body parameters of the target vehicle and the performance parameters of the piston rod connected to the shock absorber to obtain the dynamic stiffness of the upper support of the shock absorber to be tested.

[0047] Specifically, the third testing device is used to establish a whole vehicle finite element structural model and a cavity model of the target vehicle, and is also used to process and obtain the noise transfer function of the shock absorber to be tested at the corresponding installation point.

[0048] Specifically, the size of the abnormal noise in the car can be analyzed using the following abnormal noise calculation formula:

[0049] S=20lg((∫∫a(ω))K d (ω))+NTF(ω)+K(ω);

[0050] In the above formula, a(ω) is the vibration acceleration of the upper end of the piston rod of the shock absorber;

[0051] K d (ω) is the upper support dynamic stiffness of the shock absorber;

[0052] NTF(ω) is the noise transfer function from the mounting point corresponding to the shock absorber to the interior of the vehicle;

[0053] K(ω) is the first correction coefficient, which can correct the data error through empirical data accumulation;

[0054] In the above symbols, ω indicates that frequency domain representation is used.

[0055] The beneficial effects of the technical solution provided by this application include:

[0056] This application obtains the vibration acceleration of the upper end of the piston rod of the shock absorber, the dynamic stiffness of the upper support and the noise transfer function through testing. Based on this, the abnormal noise volume corresponding to the shock absorber to be tested is predicted by calculation, thereby predicting the noise level of the shock absorber and providing data basis for subsequent design optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0058] Figure 1 A flowchart of the steps of the method for predicting abnormal noise of a vehicle shock absorber provided in an embodiment of the present application;

[0059] Figure 2 A frequency domain schematic diagram of vibration acceleration of a shock absorber in a method for predicting abnormal noise of a shock absorber of a vehicle provided in an embodiment of the present application;

[0060] Figure 3 A frequency domain schematic diagram of the shock absorber displacement in the vehicle shock absorber abnormal noise prediction method provided in an embodiment of the present application;

[0061] Figure 4 A schematic diagram of the noise transfer function NTF in the vehicle shock absorber abnormal noise prediction method provided in an embodiment of the present application;

[0062] Figure 5 A schematic diagram of in-vehicle noise in a method for predicting abnormal noise of a vehicle shock absorber provided in an embodiment of the present application;

[0063] Figure 6 This is a structural block diagram of the vehicle shock absorber abnormal noise prediction system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0065] The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings.

[0066] The embodiment of the present application provides a method and system for predicting abnormal noise of a vehicle shock absorber. The vibration acceleration of the upper end of the piston rod of the shock absorber to be tested, the dynamic stiffness of the upper support and the noise transfer function are obtained through testing. Based on this, the volume of the abnormal noise corresponding to the shock absorber to be tested is predicted through calculation, thereby predicting the noise level of the shock absorber, providing a data basis for later design optimization.

[0067] In order to achieve the above technical effects, the overall idea of ​​this application is as follows:

[0068] A method for predicting abnormal noise of a vehicle shock absorber, the method comprising the following steps:

[0069] S1. Testing to obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle;

[0070] S2, simulating to obtain the upper support dynamic stiffness of the shock absorber to be tested;

[0071] S3, simulating and obtaining the noise transfer function of the shock absorber to be tested;

[0072] S4. Based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated.

[0073] The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings.

[0074] First, see Figures 1 to 5 As shown, the embodiment of the present application provides a method for predicting abnormal noise of a vehicle shock absorber, the method comprising the following steps:

[0075] S1. Testing to obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle;

[0076] S2, simulating to obtain the upper support dynamic stiffness of the shock absorber to be tested;

[0077] S3, simulating and obtaining the noise transfer function of the shock absorber to be tested;

[0078] S4. Based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated.

[0079] In the embodiment of the present application, the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested, the dynamic stiffness of the upper support and the noise transfer function are obtained through testing. Based on this, the volume of abnormal noise corresponding to the shock absorber to be tested is predicted through calculation, thereby predicting the noise level of the shock absorber, providing data basis for subsequent design optimization.

[0080] Specifically, during the daily driving of the vehicle, when the shock absorber is stimulated by uneven road surface, the shock absorber will continuously stretch and compress. During this process, the vibration of the upper end of the shock absorber passes through the upper support and impacts the vehicle body structure to vibrate and make abnormal noise.

[0081] The frequency of abnormal noise from shock absorbers generally ranges from several hundred Hz, so the upper limit frequency can be set to 1000 Hz during prediction.

[0082] The size of the abnormal noise in the car can be analyzed using the following abnormal noise calculation formula:

[0083] S=20lg((∫∫a(ω))K d (ω))+NTF(ω)+K(ω);

[0084] In the above formula, a(ω) is the vibration acceleration of the upper end of the piston rod of the shock absorber;

[0085] K d (ω) is the upper support dynamic stiffness of the shock absorber;

[0086] NTF(ω) is the noise transfer function from the mounting point corresponding to the shock absorber to the interior of the vehicle;

[0087] K(ω) is the first correction coefficient, which can correct the data error through empirical data accumulation;

[0088] In the above symbols, ω indicates that frequency domain representation is used.

[0089] Specifically, step S1, the test to obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle includes the following steps:

[0090] Installing the shock absorber to be tested on a preset shock absorber abnormal noise test stand;

[0091] A vibration exciter is connected to the lower end of the shock absorber to be tested, and a vibration sensor is arranged at the upper end of the shock absorber to be tested;

[0092] Based on the vibration exciter and the vibration sensor, testing the vibration response level of the shock absorber under different excitation inputs;

[0093] Based on the vibration response level of the shock absorber under different excitation inputs, the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested is obtained.

[0094] Specifically, in step S2, the simulation to obtain the upper support dynamic stiffness of the shock absorber to be tested includes the following steps:

[0095] Based on the body parameters of the target vehicle and the performance parameters of the piston rod connected to the shock absorber, a simulation is performed to obtain the dynamic stiffness of the upper support of the shock absorber to be tested.

[0096] Specifically, in step S3, the simulation to obtain the noise transfer function of the shock absorber to be tested includes the following steps:

[0097] Establishing a whole vehicle finite element structural model and a cavity model of the target vehicle;

[0098] The noise transfer function of the shock absorber to be tested at the corresponding installation point is obtained by processing.

[0099] Specifically, the noise transfer function of the shock absorber to be tested at the corresponding installation point may be obtained through CAE (Computer Aided Engineering) calculation or experiment.

[0100] Specifically, step S4, the step of calculating the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, includes the following steps:

[0101] Performing Fourier transformation on the vibration acceleration of the upper end of the piston rod to obtain the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum;

[0102] Performing high-pass filtering on the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum, and performing secondary integration on the result after the high-pass filtering to obtain the corresponding displacement parameter in the frequency domain;

[0103] Based on the frequency domain lower displacement parameter, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated and obtained.

[0104] Specifically, after step S4, that is, after calculating the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, the method further includes the following steps:

[0105] Comparing the abnormal noise volume corresponding to the shock absorber to be tested with a preset abnormal noise volume threshold;

[0106] When the abnormal noise volume is greater than the abnormal noise volume threshold, a structural optimization warning is generated.

[0107] In addition, the embodiment of the present application predicts the level of shock absorber noise by testing the displacement output of the shock absorber, the rubber dynamic stiffness of the shock absorber and the vehicle body, and the vehicle body noise transfer function, and performs targeted optimization on the frequencies that exceed the target values. Relying on this method, during the shock absorber development stage, the risk of abnormal noise under the vehicle loading conditions can be comprehensively considered, thereby advancing the development work and shortening the development cycle.

[0108] Based on the technical solution of the embodiment of the present application, a specific implementation operation process is given, and the specific situation is as follows:

[0109] The first step is to test the vibration acceleration a of the upper end of the piston rod of the shock absorber;

[0110] The shock absorber is installed on the shock absorber abnormal noise test bench, the exciter is connected to the lower end of the shock absorber, and the vibration sensor is arranged at the upper end of the piston rod;

[0111] Test and record the vibration response level of the shock absorber under different excitation inputs;

[0112] During bench testing, the analysis frequency f should be ensured to be above 1000 Hz and the data should be recorded for a sufficient period of time for subsequent analysis;

[0113] The excitation of the bench test can be collected from the actual road vibration and then loaded, or it can be artificially set with excitations containing different frequency and amplitude characteristics;

[0114] In combination with development needs, auxiliary devices can be added to carry out bench tests at different temperatures to verify the working differences of shock absorbers under extreme temperatures.

[0115] The second step is acceleration a data processing;

[0116] The acceleration a in the first step is transformed by Fourier to obtain the spectrum form a(ω), and the abnormal noise of the shock absorber mainly occurs in the process of stretching and reversing of the shock absorber. Therefore, the time domain data of the acceleration can be divided into two sections, one for stretching to compression and the other for compression to stretch, so as to identify the working state of the shock absorber when the abnormal noise occurs; among them,

[0117] When post-processing the signal, windowing is required to reduce leakage, and a fixed length of time period is selected for analysis. The analysis frequency is above 1000 Hz, preferably 1024 Hz.

[0118] The third step is to integrate the acceleration a(ω) to obtain the displacement;

[0119] After obtaining the frequency acceleration a(ω) in the second step, the acceleration a(ω) is high-pass filtered and the result is quadratically integrated to obtain the displacement in the frequency domain (∫∫a(ω)); where:

[0120] The purpose of high-pass filtering is to remove the constant term in the acceleration and reduce the error after integration.

[0121] Step 4: Calculate the upper support dynamic stiffness K of the shock absorber d (ω);

[0122] The upper support of the shock absorber mainly connects the piston rod and the vehicle body. It is composed of an aluminum alloy frame and internal vulcanized rubber. The stiffness value within the analysis frequency f can be obtained through experiments or simulations.

[0123] The fifth step is to calculate the noise transfer function NTF of the shock absorber;

[0124] Specifically, by establishing a finite element structural model and a cavity model of the entire vehicle, taking the support mounting points on each shock absorber as the excitation points, the noise transfer function NTF data from each excitation point to the human ear in the vehicle is calculated, and its frequency should be consistent with the above-mentioned analysis frequency f.

[0125] Step 6: Car interior noise prediction;

[0126] Based on the data from the first to fifth steps above, combined with the above-mentioned calculation formula for abnormal noise inside the car, calculate the noise data inside the car when the shock absorber passes through the impact road surface, and calculate it through K d (ω) Correct the results.

[0127] It should be noted that the noise inside the vehicle can be the result of a single shock absorber or the sum of the noises produced by multiple shock absorbers.

[0128] Based on the technical solutions of the embodiments of the present application, risk assessment and improvement can also be performed;

[0129] The noise at the rear ears obtained in the sixth step is compared with the abnormal noise volume threshold to determine the abnormal noise risk.

[0130] Assuming that the noise at the rear ear is significantly higher than the abnormal noise volume threshold at around 550Hz, the main reason is that the vibration output of the shock absorber piston rod is significantly too large, and the upper support has insufficient vibration isolation rate near this frequency, and the NTF has an obvious peak at this frequency, which together lead to the occurrence of this problem;

[0131] Therefore, the peak component of 550Hz can be reduced by optimizing the valve system and other structures of the shock absorber body, or the noise inside the car can be reduced to below the abnormal noise volume threshold by optimizing the vibration isolation rate of the upper support and the peak value of NTF.

[0132] Second, see Figure 6 As shown, an embodiment of the present application provides a vehicle shock absorber abnormal noise prediction system, which is based on the vehicle shock absorber abnormal noise prediction method mentioned in the first aspect, and the system includes:

[0133] A first testing device, which is used to test and obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle;

[0134] A second testing device, which is used to simulate and obtain the upper support dynamic stiffness of the shock absorber to be tested;

[0135] A third testing device, which is used to simulate and obtain the noise transfer function of the shock absorber to be tested;

[0136] A noise calculation device is used to calculate the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient.

[0137] In the embodiment of the present application, the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested, the dynamic stiffness of the upper support and the noise transfer function are obtained through testing. Based on this, the volume of abnormal noise corresponding to the shock absorber to be tested is predicted through calculation, thereby predicting the noise level of the shock absorber, providing data basis for subsequent design optimization.

[0138] Specifically, during the daily driving of the vehicle, when the shock absorber is stimulated by uneven road surface, the shock absorber will continuously stretch and compress. During this process, the vibration of the upper end of the shock absorber passes through the upper support and impacts the vehicle body structure to vibrate and make abnormal noise.

[0139] The frequency of abnormal noise from shock absorbers generally ranges from several hundred Hz, so the upper limit frequency can be set to 1000 Hz during prediction.

[0140] The size of the abnormal noise in the car can be analyzed using the following abnormal noise calculation formula:

[0141] S=20lg((∫∫a(ω))K d (ω))+NTF(ω)+K(ω);

[0142] In the above formula, a(ω) is the vibration acceleration of the upper end of the piston rod of the shock absorber;

[0143] K d (ω) is the upper support dynamic stiffness of the shock absorber;

[0144] NTF(ω) is the noise transfer function from the mounting point corresponding to the shock absorber to the interior of the vehicle;

[0145] K(ω) is the first correction coefficient, which can correct the data error through empirical data accumulation;

[0146] In the above symbols, ω indicates that frequency domain representation is used.

[0147] Specifically, the first testing device includes:

[0148] A shock absorber abnormal noise test stand for mounting the shock absorber to be tested;

[0149] A vibration exciter connected to the lower end of the shock absorber to be tested;

[0150] A vibration sensor is used to be connected to the upper end of the shock absorber to be tested.

[0151] Specifically, the second testing device is used to perform simulation based on the body parameters of the target vehicle and the performance parameters of the piston rod connected to the shock absorber to obtain the dynamic stiffness of the upper support of the shock absorber to be tested.

[0152] Specifically, the third testing device is used to establish a whole vehicle finite element structural model and a cavity model of the target vehicle, and is also used to process and obtain the noise transfer function of the shock absorber to be tested at the corresponding installation point.

[0153] Specifically, the noise transfer function of the shock absorber to be tested at the corresponding installation point may be obtained through CAE (Computer Aided Engineering) calculation or experiment.

[0154] Specifically, when the noise calculation device calculates the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, the calculation process includes the following:

[0155] Performing Fourier transformation on the vibration acceleration of the upper end of the piston rod to obtain the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum;

[0156] Performing high-pass filtering on the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum, and performing secondary integration on the result after the high-pass filtering to obtain the corresponding displacement parameter in the frequency domain;

[0157] Based on the frequency domain lower displacement parameter, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated and obtained.

[0158] Specifically, the vehicle shock absorber abnormal noise prediction system also includes a noise warning device, which is used to:

[0159] Comparing the abnormal noise volume corresponding to the shock absorber to be tested with a preset abnormal noise volume threshold;

[0160] When the abnormal noise volume is greater than the abnormal noise volume threshold, a structural optimization warning is generated.

[0161] In addition, the embodiment of the present application predicts the level of shock absorber noise by testing the displacement output of the shock absorber, the rubber dynamic stiffness of the shock absorber and the vehicle body, and the vehicle body noise transfer function, and performs targeted optimization on the frequencies that exceed the target values. Relying on this system, during the shock absorber development stage, the risk of abnormal noise under the vehicle loading conditions can be comprehensively considered, which advances the development work and shortens the development cycle.

[0162] Based on the technical solution of the embodiment of the present application and relying on the vehicle shock absorber abnormal noise prediction system, a specific implementation operation process is given, and the specific situation is as follows:

[0163] The first step is to test the vibration acceleration a of the upper end of the piston rod of the shock absorber;

[0164] The shock absorber is installed on the shock absorber abnormal noise test bench, the exciter is connected to the lower end of the shock absorber, and the vibration sensor is arranged at the upper end of the piston rod;

[0165] Test and record the vibration response level of the shock absorber under different excitation inputs;

[0166] During bench testing, the analysis frequency f should be ensured to be above 1000 Hz and the data should be recorded for a sufficient period of time for subsequent analysis;

[0167] The excitation of the bench test can be collected from the actual road vibration and then loaded, or it can be artificially set with excitations containing different frequency and amplitude characteristics;

[0168] In combination with development needs, auxiliary devices can be added to carry out bench tests at different temperatures to verify the working differences of shock absorbers under extreme temperatures.

[0169] The second step is acceleration a data processing;

[0170] The acceleration a in the first step is transformed by Fourier to obtain the spectrum form a(ω), and the abnormal noise of the shock absorber mainly occurs in the process of stretching and reversing of the shock absorber. Therefore, the time domain data of the acceleration can be divided into two sections, one for stretching to compression and the other for compression to stretch, so as to identify the working state of the shock absorber when the abnormal noise occurs; among them,

[0171] When post-processing the signal, windowing is required to reduce leakage, and a fixed length of time period is selected for analysis. The analysis frequency is above 1000 Hz, preferably 1024 Hz.

[0172] The third step is to integrate the acceleration a(ω) to obtain the displacement;

[0173] After obtaining the frequency acceleration a(ω) in the second step, the acceleration a(ω) is high-pass filtered and the result is quadratically integrated to obtain the displacement in the frequency domain (∫∫a(ω)); where:

[0174] The purpose of high-pass filtering is to remove the constant term in the acceleration and reduce the error after integration.

[0175] Step 4: Calculate the upper support dynamic stiffness K of the shock absorber d (ω);

[0176] The upper support of the shock absorber mainly connects the piston rod and the vehicle body. It is composed of an aluminum alloy frame and internal vulcanized rubber. The stiffness value within the analysis frequency f can be obtained through experiments or simulations.

[0177] The fifth step is to calculate the noise transfer function NTF of the shock absorber;

[0178] Specifically, by establishing a finite element structural model and a cavity model of the entire vehicle, taking the support mounting points on each shock absorber as the excitation points, the noise transfer function NTF data from each excitation point to the human ear in the vehicle is calculated, and its frequency should be consistent with the above-mentioned analysis frequency f.

[0179] Step 6: Car interior noise prediction;

[0180] Based on the data from the first to fifth steps above, combined with the above-mentioned calculation formula for abnormal noise inside the car, calculate the noise data inside the car when the shock absorber passes through the impact road surface, and calculate it through K d (ω) Correct the results.

[0181] It should be noted that the noise inside the vehicle can be the result of a single shock absorber or the sum of the noises produced by multiple shock absorbers.

[0182] Based on the technical solutions of the embodiments of the present application, risk assessment and improvement can also be performed;

[0183] The noise at the rear ears obtained in the sixth step is compared with the abnormal noise volume threshold to determine the abnormal noise risk.

[0184] Assuming that the noise at the rear ear is significantly higher than the abnormal noise volume threshold at around 550Hz, the main reason is that the vibration output of the shock absorber piston rod is significantly too large, and the upper support has insufficient vibration isolation rate near this frequency, and the NTF has an obvious peak at this frequency, which together lead to the occurrence of this problem;

[0185] Therefore, the peak component of 550Hz can be reduced by optimizing the valve system and other structures of the shock absorber body, or the noise inside the car can be reduced to below the abnormal noise volume threshold by optimizing the vibration isolation rate of the upper support and the peak value of NTF.

[0186] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0187] The above is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for predicting abnormal noise of a vehicle shock absorber, characterized in that: The method comprises the following steps: The test obtains the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle; Simulating and obtaining the dynamic stiffness of the upper support of the shock absorber to be tested; Simulating and obtaining the noise transfer function of the shock absorber to be tested; Based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated; When calculating the volume of abnormal noise, the method is configured with a calculation formula for abnormal noise in the vehicle for analysis: S=20lg((∫∫a(ω))K d (ω))+NTF(ω)+K(ω); In the above formula, a(ω) is the vibration acceleration of the upper end of the piston rod of the shock absorber; K d (ω) is the upper support dynamic stiffness of the shock absorber; NTF(ω) is the noise transfer function from the mounting point corresponding to the shock absorber to the interior of the vehicle; K(ω) is the first correction coefficient, which can correct the data error through empirical data accumulation; ω indicates that the frequency domain is used.

2. The method for predicting abnormal noise of a vehicle shock absorber according to claim 1, characterized in that: The test to obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle includes the following steps: Installing the shock absorber to be tested on a preset shock absorber abnormal noise test stand; A vibration exciter is connected to the lower end of the shock absorber to be tested, and a vibration sensor is arranged at the upper end of the shock absorber to be tested; Based on the vibration exciter and the vibration sensor, testing the vibration response level of the shock absorber under different excitation inputs; Based on the vibration response level of the shock absorber under different excitation inputs, the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested is obtained.

3. The method for predicting abnormal noise of a vehicle shock absorber according to claim 1, characterized in that: The simulation to obtain the upper support dynamic stiffness of the shock absorber to be tested includes the following steps: Based on the body parameters of the target vehicle and the performance parameters of the piston rod connected to the shock absorber, a simulation is performed to obtain the dynamic stiffness of the upper support of the shock absorber to be tested.

4. The vehicle shock absorber abnormal noise prediction method according to claim 1, characterized in that: The simulation to obtain the noise transfer function of the shock absorber to be tested includes the following steps: Establishing a whole vehicle finite element structural model and a cavity model of the target vehicle; The noise transfer function of the shock absorber to be tested at the corresponding installation point is obtained by processing.

5. The method for predicting abnormal noise of a vehicle shock absorber according to claim 1, characterized in that: The step of calculating the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient comprises the following steps: Performing Fourier transformation on the vibration acceleration of the upper end of the piston rod to obtain the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum; Performing high-pass filtering on the vibration acceleration of the upper end of the piston rod in the form of a frequency spectrum, and performing secondary integration on the result after the high-pass filtering to obtain the corresponding displacement parameter in the frequency domain; Based on the frequency domain lower displacement parameter, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient, the abnormal noise volume corresponding to the shock absorber to be tested is calculated and obtained.

6. The method for predicting abnormal noise of a vehicle shock absorber according to claim 1, characterized in that: After calculating and obtaining the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and the preset first correction coefficient, the method further includes the following steps: Comparing the abnormal noise volume corresponding to the shock absorber to be tested with a preset abnormal noise volume threshold; When the abnormal noise volume is greater than the abnormal noise volume threshold, a structural optimization warning is generated.

7. A vehicle shock absorber abnormal noise prediction system, characterized in that: The system comprises: A first testing device, which is used to test and obtain the vibration acceleration of the upper end of the piston rod of the shock absorber to be tested of the target vehicle; A second testing device, which is used to simulate and obtain the upper support dynamic stiffness of the shock absorber to be tested; A third testing device, which is used to simulate and obtain the noise transfer function of the shock absorber to be tested; A noise calculation device, which is used to calculate the abnormal noise volume corresponding to the shock absorber to be tested based on the vibration acceleration of the upper end of the piston rod, the upper support dynamic stiffness, the noise transfer function and a preset first correction coefficient; When calculating the volume of abnormal noise, the noise calculation device is equipped with an abnormal noise calculation formula for analysis: S=20lg((∫∫a(ω))K d (ω))+NTF(ω)+K(ω); In the above formula, a(ω) is the vibration acceleration of the upper end of the piston rod of the shock absorber; K d (ω) is the upper support dynamic stiffness of the shock absorber; NTF(ω) is the noise transfer function from the mounting point corresponding to the shock absorber to the interior of the vehicle; K(ω) is the first correction coefficient, which can correct the data error through empirical data accumulation; ω indicates that the frequency domain is used.

8. The vehicle shock absorber abnormal noise prediction system according to claim 7, characterized in that: The first testing device comprises: A shock absorber abnormal noise test stand for mounting the shock absorber to be tested; A vibration exciter connected to the lower end of the shock absorber to be tested; A vibration sensor is used to be connected to the upper end of the shock absorber to be tested.

9. The vehicle shock absorber abnormal noise prediction system according to claim 7, characterized in that: The second testing device is used to perform simulation based on the body parameters of the target vehicle and the performance parameters of the piston rod connected to the shock absorber to obtain the dynamic stiffness of the upper support of the shock absorber to be tested.

10. The vehicle shock absorber abnormal noise prediction system according to claim 7, characterized in that: The third testing device is used to establish a whole vehicle finite element structural model and a cavity model of the target vehicle, and is also used to process and obtain the noise transfer function of the shock absorber to be tested at the corresponding installation point.

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