Method for testing noise performance of main speed reducer of rear axle of automobile

Abstract

The invention relates to the technical field of automobile structural component testing, and particularly discloses an automobile rear axle main reducer noise performance testing method, which comprises the following steps: installing a main reducer to be tested on a specially-made test bench, and arranging noise acquisition equipment in the test bench area; simulating each test environment in the test bench area, setting each test variable, and permutation and combination of each test environment and each test variable to obtain each test factor combination, so that the to-be-tested main speed reducer operates under each test factor combination, and meanwhile, the noise acquisition equipment starts to record; acquiring noise test data of the to-be-tested main speed reducer corresponding to each test factor combination, and performing quality evaluation on the to-be-tested main speed reducer; carrying out quality disqualification reason analysis on the to-be-tested main speed reducer, and determining a fault part of the to-be-tested main speed reducer; the performance of the main speed reducer under different working conditions can be systematically evaluated, the quality of the main speed reducer can be comprehensively detected, and the design and use standards are ensured to be met.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile structural component testing, and in particular to a method for testing the noise performance of an automobile rear axle main reducer. Background Art

[0002] As a key component of the automotive transmission system, the rear drive axle assembly transfers engine torque from the universal joint to the drive wheels, while also reducing speed to increase torque. Its role in enhancing ride comfort and smoothness is becoming increasingly crucial. The rear axle final drive is a crucial component in the automotive transmission system, shifting torque and speed. The quality of the main and driven gears in the final drive, which utilizes a hypoid pinion, is directly related to the vibration response of the rear axle.

[0003] The rear axle final drive (FDR) is a crucial component of a vehicle's powertrain, and its performance directly impacts driving quality and ride comfort. Noise is a key performance metric for FDRs. Existing noise testing methods rely heavily on subjective auditory judgment or simple instrumental measurements, lacking a systematic, standardized testing process. This results in inaccurate and repeatable test results, making it difficult to meet the precision and standardization requirements of the modern automotive industry. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a method for testing the noise performance of a rear axle main reducer of an automobile.

[0005] The present invention solves the above technical problems through the following technical means: a method for testing the noise performance of a rear axle main reducer of an automobile, comprising: Step 1: Noise test preparation: Install the final reducer to be tested on a specially designed test bench. During installation, precisely align and tighten the final reducer's input shaft with the test bench's power output shaft. Set up a noise collection device within the test bench area. Step 2: Test variable setting: Simulate various test environments within the test bench area and set various test variables. Start the test bench and arrange and combine the test environments and test variables to obtain various test factor combinations. The main reducer to be tested is operated under each test factor combination, and the noise collection device starts recording at the same time. Step 3: Test data analysis: Obtain the noise test data of the main reducer to be tested corresponding to each test factor combination, analyze it, and then conduct a quality assessment of the main reducer to be tested; Step 4, test quality classification: If the quality assessment result of the main reducer to be tested is identified as qualified, proceed to step 6; otherwise, proceed to step 5; Step 5: Analyze the reasons for failure: Analyze the reasons for failure of the main reducer to be tested and determine the fault location of the main reducer to be tested; Step 6: Feedback of test results: Feedback of the quality assessment results and fault location of the main reducer to be tested to the display interface of the noise test device.

[0006] For example, the test environments in step 2 are specifically divided into a standard room temperature environment, a high temperature environment, a low temperature environment, a high humidity environment, and a variable temperature and humidity environment; The test variables specifically include set speeds and working states, wherein the set speeds are divided into low speed, medium speed and high speed, and the working states are further divided into no-load state, half-load state and full-load state.

[0007] For example, the noise test data of the main reducer to be tested corresponding to each test factor combination is analyzed, and the specific analysis process is as follows: Obtain noise test data corresponding to each test factor combination for the main reducer to be tested using noise collection equipment deployed in the test bench area. The noise test data specifically includes noise acceleration values ​​and noise signal values ​​at each test time point. Analyze the noise test data of the main reducer to be tested corresponding to each test factor combination to obtain the test value of each noise component in each test factor combination of the main reducer to be tested, where each noise component is divided into acceleration noise and self-ringing noise; Calculate the test value of acceleration noise of the main reducer to be tested corresponding to each test factor combination , is the test value of the acceleration noise of the main reducer to be tested corresponding to the kth test factor combination, k is the number of each test factor combination, k=1,2,...F, i is the number of each test time point, i=1,2,...N, N is the total number of test time points, is the noise acceleration value of the tested main reducer corresponding to the kth test factor combination at the i-th test time point; Perform fast Fourier transform on the noise signal value of the main reducer to be tested corresponding to each test factor combination at each test time point to obtain the noise spectrum diagram of the main reducer to be tested corresponding to each test factor combination, and identify the amplitude of each peak value of the self-ringing noise of the main reducer to be tested corresponding to each test factor combination , j is the number of each peak, j=1,2,...M; By analyzing the formula , get the test value of the self-ringing noise in the kth test factor combination of the main reducer to be tested , M is the number of peaks identified in the spectrogram; In summary, the comprehensive noise level value of the main reducer to be tested corresponding to each test factor combination is obtained .

[0008] Exemplarily, the quality assessment of the main reducer to be tested is performed using the following assessment logic: Calculate the quality assessment value of the main reducer to be tested , F is the total number of test factor combinations, is the set weight value of the kth test factor combination, and satisfies ; The quality assessment value of the main reducer to be tested is compared with the set reducer quality qualification threshold. If the former is less than the latter, it indicates that the quality assessment result of the main reducer to be tested is unqualified; otherwise, it indicates that the quality assessment result of the main reducer to be tested is unqualified.

[0009] For example, the specific logic for obtaining the set weight value of each test factor combination is: Obtain the total number of test factor combinations F, and construct the test factor combination judgment matrix ,in is the importance of the first test factor combination relative to the second test factor combination stored in the database, Respectively represent the importance of the first test factor combination and the second test factor combination stored in the database relative to the Fth test factor combination; Judgment matrix for test factor combination Perform normalization processing to obtain the normalized matrix of test factor combinations ; Further calculation is performed to obtain the set weight value of each test factor combination. The calculation formula is as follows: A consistency test is performed on the test factor combination judgment matrix to obtain the consistency ratio CR of the test factor combination judgment matrix. If the consistency ratio CR of the test factor combination judgment matrix is ​​identified to be less than 0.1, it indicates that the set weight values ​​of each test factor combination do not need to be adjusted. Otherwise, the test factor combination judgment matrix is ​​readjusted and the set weight values ​​of each test factor combination are recalculated according to the above steps.

[0010] For example, the consistency ratio CR of the test factor combination judgment matrix is ​​obtained, and the specific calculation process is as follows: Calculate the maximum eigenvalue of the test factor combination judgment matrix ,in , , , are the set weight values ​​for the first test factor combination, the second test factor combination, and the Fth test factor combination, respectively. , , ; Calculate the consistency index of the test factor combination judgment matrix ; A noise test device is used to randomly generate the average consistency index value of a large number of test factor combination judgment matrices, and the random consistency index RI of the test factor combination judgment matrix is ​​obtained; The consistency ratio of the test factor combination judgment matrix is ​​calculated .

[0011] For example, the specific analysis logic for analyzing the reasons for quality failure of the main reducer to be tested is as follows: Use noise collection equipment to record the gear speed of the main reducer to be tested corresponding to each test factor combination and bearing speed ; Calculate the gear meshing frequency of the final drive to be tested , CS is the number of gear teeth of the main reducer to be tested; Calculate the bearing failure frequency of the main reducer to be tested , r is the rolling element diameter, R is the raceway diameter, is the contact angle of the rolling element, and Z is the number of rolling elements.

[0012] Exemplarily, the specific process of determining the fault location of the main reducer to be tested is as follows: Compare the gear meshing frequency of the main reducer to be tested with the predefined qualified threshold of the gear meshing frequency of the rear axle main reducer of the vehicle. If the former is less than the latter, it is determined that the fault location of the main reducer to be tested is a gear fault; The bearing fault frequency of the main reducer to be tested is compared with the predefined qualified threshold of the bearing fault frequency of the rear axle main reducer of the vehicle. If the former is less than the latter, it is determined that the fault location of the main reducer to be tested is a bearing fault.

[0013] For example, determining that the fault location of the main reducer to be tested is a bearing fault further includes the following analysis process: Obtain the bearing inner ring fault frequency of the main reducer to be tested ; Obtain the fault frequency of the outer ring of the main reducer to be tested ; Obtain the bearing rolling element failure frequency of the main reducer to be tested ; The bearing inner race fault frequency, bearing outer race fault frequency and bearing rolling element fault frequency of the main reducer to be tested are compared with the predefined bearing fault frequency qualified threshold value to obtain the fault type of the bearing fault of the main reducer to be tested.

[0014] Beneficial effects of the present invention: The present invention provides a method for testing the noise performance of a rear axle main reducer of an automobile. The method comprises the following steps: installing the main reducer to be tested on a specially designed test bench and setting a noise collection device in the test bench area; simulating various test environments in the test bench area and setting various test variables; starting the test bench and permuting and combining the test environments and test variables to obtain various test factor combinations, causing the main reducer to be tested to operate under the various test factor combinations; and simultaneously starting the noise collection device to record noise; obtaining noise test data corresponding to the various test factor combinations of the main reducer to be tested, thereby performing a quality assessment on the main reducer to be tested; and analyzing the reasons for quality failure of the main reducer to be tested to determine the fault location of the main reducer to be tested. On the one hand, the method can simulate various actual use environments and working conditions, set different test variables, and comprehensively understand the operation of the main reducer under different conditions. By permuting and combining the test environments and variables, multiple test factor combinations can be generated, causing the main reducer to operate under various possible actual use scenarios, thereby obtaining more comprehensive and realistic noise data. On the other hand, by analyzing the noise data, the noise characteristics of the main reducer under different working conditions can be identified, thereby determining the stability and reliability of its operation. If quality issues are detected, further noise data analysis can be performed to determine the cause of the abnormal noise and the specific location of the fault. This detailed fault analysis helps manufacturers quickly identify the root cause of the problem, implement targeted improvements and design optimizations, and improve overall product quality. Furthermore, it can significantly reduce product failure rates and safety risks in actual use, increasing user satisfaction and trust. By identifying and resolving potential issues during the testing phase, large-scale quality issues can be avoided in the market, reducing recall and repair costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the connection structure of the method steps of the present invention. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0017] See also Figure 1 As shown, a method for testing the noise performance of a rear axle main reducer of an automobile comprises: Step 1: Noise test preparation: Install the final reducer to be tested on a specially designed test bench. During installation, precisely align and tighten the final reducer's input shaft with the test bench's power output shaft. Set up a noise collection device within the test bench area. Step 2: Test variable setting: Simulate various test environments within the test bench area and set various test variables. Start the test bench and arrange and combine the test environments and test variables to obtain various test factor combinations. The main reducer to be tested is operated under each test factor combination, and the noise collection device starts recording at the same time. Based on the above embodiment, the test environments in step 2 are specifically divided into standard room temperature environment, high temperature environment, low temperature environment, high humidity environment and variable temperature and humidity environment; The test variables specifically include set speeds and working states, wherein the set speeds are divided into low speed, medium speed and high speed, and the working states are further divided into no-load state, half-load state and full-load state.

[0018] It should be added that the temperature in the standard room temperature environment is about 20°C to 25°C (68°F to 77°F), and the humidity is generally around 50% relative humidity; the temperature in the high temperature environment: can be set at 50°C to 80°C (122°F to 176°F) to simulate hot weather or the temperature inside the engine compartment, and the relative humidity can be lower because high temperature usually reduces the relative humidity of the air; the temperature in the low temperature environment can be set at -20°C to 0C (-4°F to 32°F) to simulate winter or cold area conditions, and the relative humidity may be higher, especially when close to freezing; the temperature in the high humidity environment: usually 20°C to 30°C (68°F to 86°F), and the relative humidity can be set at 80% to 95% to simulate humid weather conditions; a temperature and humidity cycle is set in the variable temperature and humidity environment to simulate a changing environment from low temperature to high temperature, and from low humidity to high humidity.

[0019] It should be added that the test environments and test variables are arranged and combined. The specific arrangement process is as follows: The total number of test factor combinations F = the total number of test environments Set the total number of speeds Total number of working states; The combinations of various test factors can be shown in the following table:

[0020] Step 3: Test data analysis: Obtain the noise test data of the main reducer to be tested corresponding to each test factor combination, analyze it, and then conduct a quality assessment of the main reducer to be tested; Based on the above embodiment, the noise test data of the main reducer to be tested corresponding to each test factor combination is analyzed. The specific analysis process is as follows: Obtain noise test data corresponding to each test factor combination for the main reducer to be tested using noise collection equipment deployed in the test bench area. The noise test data specifically includes noise acceleration values ​​and noise signal values ​​at each test time point. Analyze the noise test data of the main reducer to be tested corresponding to each test factor combination to obtain the test value of each noise component in each test factor combination of the main reducer to be tested, where each noise component is divided into acceleration noise and self-ringing noise; The final reducer of an automobile is primarily composed of components such as gears, shafts, bearings, and a housing. Due to errors in the manufacturing and actual assembly processes, and the influence of factors such as load changes during operation, the final reducer will vibrate during operation, which in turn excites air vibrations and produces radiated noise. This noise is generally composed of two parts: first, the noise generated by the impact of components such as gears and rolling bearings during operation, which is called acceleration noise; second, the noise generated by the housing under the excitation of the dynamic combined force of the gear system, which is called self-ringing noise. Calculate the test value of acceleration noise of the main reducer to be tested corresponding to each test factor combination , is the test value of the acceleration noise of the main reducer to be tested corresponding to the kth test factor combination, k is the number of each test factor combination, k=1,2,...F, i is the number of each test time point, i=1,2,...N, N is the total number of test time points, is the noise acceleration value of the tested main reducer corresponding to the kth test factor combination at the i-th test time point; Perform fast Fourier transform on the noise signal value of the main reducer to be tested corresponding to each test factor combination at each test time point to obtain the noise spectrum diagram of the main reducer to be tested corresponding to each test factor combination, and identify the amplitude of each peak value of the self-ringing noise of the main reducer to be tested corresponding to each test factor combination , j is the number of each peak, j=1,2,...M; It should be added that the noise spectrum of the main reducer to be tested corresponding to each test factor combination is obtained. The specific acquisition steps are as follows: Step 11: Sample the noise signal value of each test factor combination of the main reducer to be tested at each test time point, and set the sampling frequency to , then the sampling interval is , thus obtaining the time domain noise signal of the main reducer to be tested corresponding to each test factor combination at each test time point , c is the index of the sampling point, c=1,2,...H; Step 12: Use fast Fourier transform to convert the time domain noise signal of each test factor combination of the main reducer to be tested at each test time point into a frequency domain noise signal. , r is the unit of the imaginary part of the complex number, d is the frequency index, and H is the total number of sampling points; Step 13: Calculate the FFT result amplitude of each test factor combination of the main reducer to be tested. , are the real and imaginary parts of the frequency domain noise signal respectively; Step 14: Define the horizontal axis of the noise spectrum of the main reducer to be tested corresponding to each test factor combination as frequency. , the vertical axis is the amplitude Plot the spectrum.

[0021] By analyzing the formula , get the test value of the self-ringing noise in the kth test factor combination of the main reducer to be tested , M is the number of peaks identified in the spectrogram; In summary, the comprehensive noise level value of the main reducer to be tested corresponding to each test factor combination is obtained .

[0022] Based on the above embodiment, the quality assessment of the main reducer to be tested is performed, and the assessment logic is as follows: Calculate the quality assessment value of the main reducer to be tested , F is the total number of test factor combinations, is the set weight value of the kth test factor combination, and satisfies ; The quality assessment value of the main reducer to be tested is compared with the set reducer quality qualification threshold. If the former is less than the latter, it indicates that the quality assessment result of the main reducer to be tested is unqualified; otherwise, it indicates that the quality assessment result of the main reducer to be tested is unqualified.

[0023] Based on the above embodiment, the specific logic for obtaining the set weight value of each test factor combination is as follows: Obtain the total number of test factor combinations F, and construct the test factor combination judgment matrix ,in is the importance of the first test factor combination relative to the second test factor combination stored in the database, Respectively represent the importance of the first test factor combination and the second test factor combination stored in the database relative to the Fth test factor combination; Judgment matrix for test factor combination Perform normalization processing to obtain the normalized matrix of test factor combinations ; Further calculation is performed to obtain the set weight value of each test factor combination. The calculation formula is as follows: A consistency test is performed on the test factor combination judgment matrix to obtain the consistency ratio CR of the test factor combination judgment matrix. If the consistency ratio CR of the test factor combination judgment matrix is ​​identified to be less than 0.1, it indicates that the set weight values ​​of each test factor combination do not need to be adjusted. Otherwise, the test factor combination judgment matrix is ​​readjusted and the set weight values ​​of each test factor combination are recalculated according to the above steps.

[0024] Based on the above embodiment, the consistency ratio CR of the test factor combination judgment matrix is ​​obtained. The specific calculation process is: Calculate the maximum eigenvalue of the test factor combination judgment matrix ,in , , , are the set weight values ​​for the first test factor combination, the second test factor combination, and the Fth test factor combination, respectively. , , ; Calculate the consistency index of the test factor combination judgment matrix ; A noise test device is used to randomly generate the average consistency index value of a large number of test factor combination judgment matrices, and the random consistency index RI of the test factor combination judgment matrix is ​​obtained; The consistency ratio of the test factor combination judgment matrix is ​​calculated .

[0025] Step 4, test quality classification: If the quality assessment result of the main reducer to be tested is identified as qualified, proceed to step 6; otherwise, proceed to step 5; Step 5: Analyze the reasons for failure: Analyze the reasons for failure of the main reducer to be tested and determine the fault location of the main reducer to be tested; Based on the above embodiment, the specific analysis logic for the reasons for the quality failure of the main reducer to be tested is as follows: Use noise collection equipment to record the gear speed of the main reducer to be tested corresponding to each test factor combination and bearing speed ; Calculate the gear meshing frequency of the final drive to be tested , CS is the number of gear teeth of the main reducer to be tested; Calculate the bearing failure frequency of the main reducer to be tested , r is the rolling element diameter, R is the raceway diameter, is the contact angle of the rolling element, and Z is the number of rolling elements.

[0026] On the basis of the above embodiment, the specific process of determining the fault location of the main reducer to be tested is as follows: Compare the gear meshing frequency of the main reducer to be tested with the predefined qualified threshold of the gear meshing frequency of the rear axle main reducer of the vehicle. If the former is less than the latter, it is determined that the fault location of the main reducer to be tested is a gear fault; The bearing fault frequency of the main reducer to be tested is compared with the predefined qualified threshold of the bearing fault frequency of the rear axle main reducer of the vehicle. If the former is less than the latter, it is determined that the fault location of the main reducer to be tested is a bearing fault.

[0027] Based on the above embodiment, determining that the fault location of the main reducer to be tested is a bearing fault also includes the following analysis process: Obtain the bearing inner ring fault frequency of the main reducer to be tested ; Obtain the fault frequency of the outer ring of the main reducer to be tested ; Obtain the bearing rolling element failure frequency of the main reducer to be tested ; Compare the bearing inner race fault frequency, bearing outer race fault frequency, and bearing rolling element fault frequency of the main reducer to be tested with the predefined bearing fault frequency qualified threshold value to obtain the fault type of the bearing fault of the main reducer to be tested; If the bearing inner ring fault frequency of the main reducer to be tested is less than the predefined bearing fault frequency qualification threshold, the fault type of the bearing fault of the main reducer to be tested is defined as a bearing inner ring fault; if the bearing outer ring fault frequency of the main reducer to be tested is less than the predefined bearing fault frequency qualification threshold, the fault type of the bearing fault of the main reducer to be tested is defined as a bearing outer ring fault; if the bearing rolling element fault frequency of the main reducer to be tested is less than the predefined bearing fault frequency qualification threshold, the fault type of the bearing fault of the main reducer to be tested is defined as a bearing rolling element fault.

[0028] Step 6: Feedback of test results: Feedback of the quality assessment results and fault location of the main reducer to be tested to the display interface of the noise test device.

[0029] It should be added that if the quality assessment result of the main reducer to be tested is identified as qualified, the fault location of the main reducer to be tested in the display interface of the noise testing device will be displayed as blank.

[0030] The above content is merely an example and explanation of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

[0031] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0032] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for testing the noise performance of a rear axle main reducer of an automobile, characterized in that: The method comprises the following steps: Step 1: Noise test preparation: Install the main reducer to be tested on a special test bench. During installation, the input shaft of the main reducer and the power output shaft of the test bench are accurately aligned and tightened, and a noise collection device is set in the test bench area; Step 2, test variable setting: simulate various test environments in the test bench area, set various test variables, start the test bench, and arrange and combine various test environments and test variables to obtain various test factor combinations, so that the main reducer to be tested operates under various test factor combinations, and the noise collection device starts recording at the same time; Step 3, test data analysis: obtain the noise test data of the main reducer to be tested corresponding to each test factor combination, analyze it, and then conduct quality assessment on the main reducer to be tested; Step 4, test quality classification: if the quality assessment result of the main reducer to be tested is identified as qualified, then execute step 6, otherwise continue to execute step 5; Step 5, failure reason analysis: Analyze the failure reason of the main reducer to be tested, and determine the fault location of the main reducer to be tested; Step 6: Feedback of test results: Feedback of the quality assessment results and fault location of the main reducer to be tested to the display interface of the noise test device.

2. A method for testing the noise performance of a rear axle main reducer of an automobile according to claim 1, characterized in that: In step 2, each test environment is specifically divided into a standard room temperature environment, a high temperature environment, a low temperature environment, a high humidity environment, and a variable temperature and humidity environment; The test variables specifically include set speeds and working states, wherein the set speeds are divided into low speed, medium speed and high speed, and the working states are further divided into no-load state, half-load state and full-load state.

3. The method for testing the noise performance of a rear axle main reducer of an automobile according to claim 1, characterized in that: The noise test data of the main reducer to be tested corresponding to each test factor combination are analyzed. The specific analysis process is as follows: According to the noise collection equipment arranged in the test bench area, the noise test data of the main reducer to be tested corresponding to each test factor combination is obtained, and the noise test data specifically includes the noise acceleration value and the noise signal value at each test time point; The noise test data of the main reducer to be tested corresponding to each test factor combination are analyzed to obtain the test value of each noise component in each test factor combination of the main reducer to be tested, wherein each noise component is divided into acceleration noise and self-ringing noise; Calculate the test value of acceleration noise of the main reducer to be tested corresponding to each test factor combination , is the test value of the acceleration noise in the kth test factor combination of the main reducer to be tested, k is the number of each test factor combination, k=1,2,...F, i is the number of each test time point, i=1,2,...N, N is the total number of test time points, is the noise acceleration value of the tested main reducer corresponding to the kth test factor combination at the i-th test time point; The noise signal value of each test factor combination of the main reducer to be tested at each test time point is subjected to fast Fourier transform to obtain the noise spectrum diagram of each test factor combination of the main reducer to be tested, and the amplitude of each peak value of the self-ringing noise of each test factor combination of the main reducer to be tested is identified. , j is the number of each peak, j=1,2,...M; By analyzing the formula , get the test value of the self-ringing noise in the kth test factor combination of the main reducer to be tested , M is the number of peaks identified in the spectrum graph; In summary, the comprehensive noise level value of the main reducer to be tested corresponding to each test factor combination is obtained. .

4. A method for testing the noise performance of a rear axle main reducer of an automobile according to claim 3, characterized in that: The quality assessment of the main reducer to be tested is performed, and the assessment logic is: Calculate the quality assessment value of the main reducer to be tested , F is the total number of test factor combinations, is the set weight value for the kth test factor combination, and satisfies ; The quality assessment value of the main reducer to be tested is compared with the set reducer quality qualification threshold. If the former is smaller than the latter, it indicates that the quality assessment result of the main reducer to be tested is unqualified; otherwise, it indicates that the quality assessment result of the main reducer to be tested is unqualified.

5. The method for testing the noise performance of a rear axle main reducer of an automobile according to claim 4, characterized in that: The specific logic for obtaining the set weight value of each test factor combination is: Obtain the total number of test factor combinations F, and construct the test factor combination judgment matrix ,in is the importance of the first test factor combination relative to the second test factor combination stored in the database, They respectively represent the importance of the first test factor combination and the second test factor combination stored in the database relative to the Fth test factor combination; Combination judgment matrix for test factors Perform normalization to obtain the normalized matrix of test factor combinations ; Further calculation is performed to obtain the set weight value of each test factor combination, and the calculation formula is as follows: A consistency check is performed on the test factor combination judgment matrix to obtain the consistency ratio CR of the test factor combination judgment matrix. If the consistency ratio CR of the test factor combination judgment matrix is ​​identified to be <0.1, it indicates that the set weight values ​​of each test factor combination do not need to be adjusted. Otherwise, the test factor combination judgment matrix is ​​readjusted and the set weight values ​​of each test factor combination are recalculated according to the above steps.

6. A method for testing the noise performance of a rear axle main reducer of an automobile according to claim 5, characterized in that: The consistency ratio CR of the test factor combination judgment matrix is ​​obtained. The specific calculation process is: Calculate the maximum eigenvalue of the test factor combination judgment matrix ,in , , , are the set weight values ​​for the first test factor combination, the second test factor combination, and the Fth test factor combination, respectively. , , ; Calculate the consistency index of the test factor combination judgment matrix ; A noise test device is used to randomly generate the average consistency index value of a large number of test factor combination judgment matrices, and a random consistency index RI of the test factor combination judgment matrix is ​​obtained; The consistency ratio of the test factor combination judgment matrix is ​​calculated .

7. The method for testing the noise performance of a rear axle main reducer of an automobile according to claim 1, characterized in that: The specific analysis logic for the reasons for the quality failure of the main reducer to be tested is as follows: Use noise collection equipment to record the gear speed of the main reducer to be tested corresponding to each test factor combination and bearing speed ; Calculate the gear meshing frequency of the final drive to be tested , CS is the number of gear teeth of the main reducer to be tested; Calculate the bearing failure frequency of the main reducer to be tested , r is the rolling element diameter, R is the raceway diameter, is the contact angle of the rolling element, and Z is the number of rolling elements.

8. The method for testing the noise performance of a rear axle main reducer of an automobile according to claim 7, characterized in that: The specific process of determining the fault location of the main reducer to be tested is as follows: The gear meshing frequency of the main reducer to be tested is compared with the predefined qualified threshold of the gear meshing frequency of the rear axle main reducer of the vehicle. If the former is less than the latter, it is determined that the fault part of the main reducer to be tested is a gear fault; The bearing fault frequency of the main reducer to be tested is compared with the predefined qualified threshold of the bearing fault frequency of the rear axle main reducer of the vehicle. If the former is less than the latter, it is determined that the faulty part of the main reducer to be tested is a bearing fault.

9. A method for testing the noise performance of a rear axle main reducer of an automobile according to claim 8, characterized in that: Determining that the fault location of the main reducer to be tested is a bearing fault also includes the following analysis process: Obtain the bearing inner ring fault frequency of the main reducer to be tested ; Obtain the fault frequency of the outer ring of the main reducer to be tested ; Obtain the bearing rolling element failure frequency of the main reducer to be tested ; The bearing inner ring fault frequency, bearing outer ring fault frequency and bearing rolling element fault frequency of the main reducer to be tested are respectively compared with the predefined bearing fault frequency qualified threshold value to obtain the fault type of the bearing fault of the main reducer to be tested.

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