Bench signal setting method and test method for subframe durability test

Abstract

The present application relates to the technical field of automotive component testing, and includes a bench signal setting method and a test method for a subframe durability test. The bench signal setting method comprises the following steps: deriving an accelerator pedal signal and a motor torque signal; dividing the torque value range that the motor can achieve into several key torque segments, and calculating the different torque proportions of all motor torque values ​​within each key torque segment; calculating each sinusoidal suspension load corresponding to each key torque segment using the segment points of each key torque segment and known motor parameters; calculating the total number of cycles based on the number of accelerator pedal steppings corresponding to the accelerator pedal signal within a set time period, and multiplying the total number of cycles by the different torque proportions to obtain the number of cycles corresponding to each sinusoidal suspension load. The bench signal setting method and test method of the present application solve the problem of overly general consideration of the suspension load generated by the motor torque on the subframe in the subframe durability test.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile component testing, and in particular to a bench signal setting method and a testing method for a subframe durability test. Background Art

[0002] Currently, the subframe is a crucial component of the suspension system, typically providing mounting holes for components such as the suspension and powertrain. It is subject to complex loads, including those from the road and powertrain. Verifying the reliability and durability of the subframe through full vehicle testing is costly and time-consuming, and is typically performed using accelerated load testing, with the subframe placed on a test bench.

[0003] In related technologies, traditional subframe durability test protocols primarily consider the impact of road loads on the subframe, while the impact of the motor on the subframe is considered directly and generally. The motor is primarily mounted on the subframe in a pendulum-like configuration, with the motor torque primarily applying force to the subframe in the X-direction. Traditional subframe durability test protocols generally use the maximum motor torque value as the X-direction load applied to the subframe, and then add the road load to conduct a durability test on the subframe.

[0004] However, while traditional subframe durability test protocols verify durability, they create significant durability redundancy, making the subframe too expensive and heavy. With the advancement of electrification, the layout of motors has also changed further, from a pendulum-style arrangement to a three-point arrangement on the subframe. The subframe is subject to the Z-direction load generated by the motor torque. However, when conducting durability tests on subframes using traditional subframe durability test protocols, both the X-direction and Z-direction suspension loads are considered too generally. Summary of the Invention

[0005] The present application provides a bench signal setting method and a test method for a subframe durability test, which solves the problem that the suspension load generated by the motor torque on the subframe in the traditional subframe durability test is considered too generally.

[0006] The present application discloses a bench signal setting method for a subframe durability test, comprising the following steps:

[0007] The accelerator pedal signals and motor torque signals of a set number of vehicles within a set time period are exported from an existing background test history database. The motor torque value is obtained based on the motor torque signal, the torque value range that the motor can achieve is divided into several key torque segments, and the different torque proportions of all motor torque values ​​within each key torque segment are calculated.

[0008] Calculate the sinusoidal suspension loads of the subframe on which the motor is mounted, corresponding to each key torque segment, using the segment points of each key torque segment and known motor parameters;

[0009] Based on the number of accelerator pedal depressions corresponding to the accelerator pedal signal within a set time period, the total number of cycles of all sinusoidal mount loads within a set number of years is calculated, and the total number of cycles is multiplied by the different torque proportions to obtain the corresponding number of cycles for each sinusoidal mount load.

[0010] Based on the above technical solution, the number of vehicles is set to n; the torque range that can be achieved by the motor is divided into several key torque segments, and the different torque proportions of all motor torque values ​​in each key torque segment are calculated, including:

[0011] Divide the achievable torque range of the motor into m common torque segments, randomly sample the relevant signals of n1 vehicles, extract all the motor torque values ​​of each vehicle, and calculate the different torque proportions of all the motor torque values ​​of each vehicle within the m common torque segments, thus obtaining the torque proportions of each of the n1 vehicles within the m common torque segments;

[0012] The segments are aggregated to form m0 key torque segments, and the torque proportion of each key torque segment is obtained.

[0013] Based on the above technical solution, the method of extracting all motor torque values ​​of each vehicle and counting the torque proportion of each motor torque value in m common torque sections includes:

[0014] After extracting all motor torque values ​​of each vehicle, the arithmetic average method is used to calculate the different torque proportions of all motor torque values ​​in m common torque segments.

[0015] On the basis of the above technical solution, the segment aggregation is performed to form m0 key torque segments, including:

[0016] When dividing the m0 key torque sections, the torque proportions of more than 80% of the n1 vehicles fall into the m0 key torque sections.

[0017] Based on the above technical solution, the calculation of each sinusoidal suspension load of the subframe where the motor is mounted corresponding to each key torque segment using the segment points of each key torque segment and known motor parameters includes:

[0018] Merge a critical torque segment with the smallest segment point into an adjacent critical torque segment, set m0-1 load torque segments corresponding to the critical torque segments one by one, and the torque proportion of the m0-1 load torque segments corresponds to each key torque segment after the merger; adjust the smallest critical torque negative segment point in the m0 key torque segments down to a set value, as the load fixed torque lower limit value of each load torque segment; use the largest positive segment point in the m common torque segments as the load torque upper limit segment point of the maximum load torque segment; use the upper limit segment points of the remaining key torque segments except the largest and smallest in the merged m0-1 key torque segments as the load torque upper limit segment points of the remaining load torque segments;

[0019] Based on the m0-1 load torque sections and the known motor parameters, the sinusoidal suspension loads in each section corresponding to the motor installation position of the subframe are calculated.

[0020] Based on the above technical solution, the sinusoidal suspension load of each section corresponding to the motor installation position of the subframe is calculated according to the load torque section and the known motor parameters, including:

[0021] Each load torque section has a load fixed torque lower limit value and a load torque upper limit section point;

[0022] In each load torque section, the minimum load is calculated based on the lower limit value of the load fixed torque combined with the known motor parameters, and the maximum load is calculated based on the upper limit section point of the load torque combined with the known motor parameters. Half of the difference between the maximum load and the minimum load is used as the amplitude of the sinusoidal suspension load, and the maximum load minus the amplitude is used as the mean value of the sinusoidal suspension load. The set frequency is used as the frequency of the sinusoidal suspension load to obtain the sinusoidal suspension load of each section.

[0023] On the basis of the above technical solution, the calculation of the total number of cycles of all sinusoidal suspended loads within a set period of time based on the number of accelerator pedal depressions corresponding to the accelerator pedal signal within a set time period includes:

[0024] The time period is set to L days, the set period is set to 10 years, and the total number of cycles is Z. The set number of vehicles is n. The number of accelerator pedal strokes of n2 vehicles is randomly selected. The cumulative proportion from 0 to the set number of pedal strokes X is calculated in sequence at a set interval, rounded to 90%, and the result is that each vehicle has a 90% probability of pedaling the accelerator 0 to X times. X is used as the number of accelerator pedal strokes for each vehicle in L days, and Z is calculated as X / L×365×10.

[0025] On the basis of the above technical solution, after obtaining the total number of cycles Z, the total number of cycles is multiplied by the different torque proportions of the m0-1 load torque sections to obtain the number of cycles corresponding to each sinusoidal suspension load.

[0026] Based on the above technical solution, m is equal to 37, and the torque value range that the motor can achieve is divided into 37 common torque segments, namely <-120, -120~-110, -110~-100, -100~-90, ... 210~220, 220~230, and >230; the unit is N·m; m0 is equal to 5, and the five key torque segments are <-40, -40~20, 20~80, 8~150 and ≥150; the four load torque segments are -100~20, -100~80, -100~150, and -100~230.

[0027] The present application also discloses a test method using the above-mentioned bench signal setting method, wherein the subframe durability test is performed using the subframe bench signal. When the cycle is completed, if the subframe is not cracked, the subframe is qualified; otherwise, it is unqualified.

[0028] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0029] 1. The bench signal setting method of the present application is cleverly designed, which divides the torque range that the motor can achieve into several key torque sections; uses the section points of the key torque sections and the known motor parameters to calculate the size of each sinusoidal suspension load of the corresponding subframe; calculates the distribution ratio of each sinusoidal suspension load of the subframe based on the distribution law of all motor torque values ​​in several key torque sections; uses the motor torque signal in a set time period to calculate the total number of cycles of all sinusoidal suspension loads within a set period; multiplies the distribution ratio of each sinusoidal suspension load by the total number of cycles to obtain the number of cycles corresponding to each sinusoidal suspension load; the size of each sinusoidal suspension load and the number of cycles corresponding to each sinusoidal suspension load form a subframe bench signal, which can verify whether the durability of the subframe within the set period is qualified, and solves the problem of over-generalization of the suspension load generated by the motor torque on the subframe in the subframe durability test. The bench signal setting method of the present application directly obtains the suspension load at the subframe motor mounting position through vehicle historical data, establishes the correlation between the subframe bench test and the vehicle, and makes the structure of the subframe durability test more realistic and reliable.

[0030] 2. The test bench signal setting method of the present application first passes through the common torque segment and then the key torque segment, and then obtains the load torque segment through the key torque segment, and sets m0-1 load torque segments corresponding to the merged key torque segments. The torque proportion of the m0-1 load torque segments corresponds to the merged m0-1 key torque segments, and the torque proportion of the m0-1 load torque segments is obtained;

[0031] The smallest negative segment point of the key torque in the m0 key torque segments is lowered by a set value as the lower limit value of the load fixed torque of each load torque segment; the largest positive segment point in the m ordinary torque segments is used as the upper limit segment point of the load torque of the maximum load torque segment; the upper limit segment points of the remaining key torque segments except the key torque segment with the largest segment point in the merged m0-1 key torque segments are used as the upper limit segment points of the load torque of the remaining load torque segments, and the various segment points of the m0-1 load torque segments are obtained. Then, combined with the known motor parameters, the size and proportion distribution of the sinusoidal suspension load in each segment of the motor installation position of the subframe can be calculated to form the required bench signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. 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 any creative work.

[0033] Figure 1 This is a flowchart of the gantry signal setting method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 this application.

[0035] The embodiment of the present application provides a bench signal setting method for a subframe durability test, which solves the problem of overly generalizing the suspension load generated by the motor torque on the subframe in the subframe durability test.

[0036] In automotive applications, there are two main types of motor layouts. In the first, the motor is mounted on the subframe in a pendulum-like configuration with a single mounting point, subjecting the subframe primarily to X-direction loads. In the second, the motor is mounted on the subframe in a three-point configuration with three mounting points. During acceleration from a start, during driving acceleration, and during deceleration, the motor's rotation imposes significant Z-direction loads on the subframe, significantly impacting its durability. In this application, X-direction and Z-direction loads are collectively referred to as suspension loads.

[0037] Therefore, the bench signal setting method for the subframe durability test of the present application more accurately considers the suspension load generated by the motor torque on the subframe in combination with vehicle information in the subframe durability test, which can make the results of the subframe durability test more realistic and reliable.

[0038] Furthermore, when the motor accelerates, the motor torque value is positive, generating a suspended load on the sub-frame; when the motor decelerates, the motor torque value is negative, generating a suspended positive load on the sub-frame.

[0039] The reason for using sinusoidal signals to characterize suspended loads is that sinusoidal signals are widely used as typical signals or test signals in practice. Any complex signal can be decomposed into the superposition of many sinusoidal signals with different frequencies and amplitudes through Fourier transform, and sinusoidal signals are just the right way to represent suspended loads.

[0040] The present application discloses an embodiment of a method for setting a bench signal for a subframe durability test, comprising the following steps:

[0041] S1: The accelerator pedal signals and motor torque signals for a set number of vehicles within a set time period are derived from an existing backend test history database. The motor torque value is obtained based on the motor torque signal. The achievable torque range of the motor is divided into several key torque segments, and the torque contribution of all motor torque values ​​within each key torque segment is calculated.

[0042] Specifically, the accelerator pedal signal primarily includes the number of times the accelerator pedal is depressed. The motor torque signal primarily includes the motor torque value. Specifically, the set time period is typically in days, such as 7 days. The set quantity is typically an integer in the hundreds or thousands, such as 2,000 units.

[0043] Specifically, calculating the different torque proportions of all motor torque values ​​within each key torque range can provide a basis for calculating the number of subsequent sinusoidal suspension load cycles. Specifically, the existing background test history database exports the accelerator pedal signals and motor torque signals of a set number of vehicles within a set time period. The set number of vehicles must be of the same model with the same type of motor.

[0044] S2: Using the segment points of each key torque segment and the known motor parameters, calculate the various sinusoidal suspension loads of the subframe corresponding to each key torque segment.

[0045] Specifically, the required sinusoidal suspension loads can be calculated using the known motor torque values ​​at the key torque segment points, the motor parameters, and the subframe structural parameters. Specifically, the known key torque segment points and motor parameters are used to calculate the unknown sinusoidal suspension loads on the subframe where the motor is mounted, laying the foundation for generating the subframe test signal.

[0046] S3: Based on the number of accelerator pedal depressions corresponding to the accelerator pedal signal within the set time period, the total number of cycles of all sinusoidal mount loads within the set years is calculated; the total number of cycles is multiplied by the different torque proportions to obtain the number of cycles corresponding to each sinusoidal mount load, and the sinusoidal mount load and the number of cycles corresponding to each sinusoidal mount load generate a subframe bench signal.

[0047] Specifically, based on the number of times the accelerator pedal is depressed within a set time period, the total number of cycles of all sinusoidal suspension loads within the set period is calculated, and the number of cycles is allocated to each sinusoidal suspension load to obtain the required subframe bench signal. This signal is used to load the subframe with the suspension load, and the result of whether the subframe durability within the set period is qualified can be obtained.

[0048] Specifically, the set age refers to the service life of a vehicle corresponding to 300,000 kilometers.

[0049] Specifically, it is worth mentioning that the reason for deriving only the accelerator pedal signal is:

[0050] The number of times the accelerator pedal is stepped on is much greater than the number of times the brake pedal is stepped on. The number of times the accelerator pedal is stepped on is used to calculate the total number of cycles of all sinusoidal mount loads within a set number of years. Within the total number of cycles, the sinusoidal mount load is represented by a sinusoidal signal. The sinusoidal signal has both positive and negative values, and the positive and negative times are equal. The positive value of the sinusoidal mount load can correspond to the accelerator pedal signal, and the negative value of the sinusoidal mount load can correspond to the brake pedal signal. It not only completely covers the number of positive torques of the motor of the accelerator pedal, but also completely covers and exceeds the number of negative torques of the motor of the decelerator pedal. Under such a sinusoidal mount load, if there is no problem with the durability of the subframe, then there will be no problem with the durability of the subframe during the actual operation of the vehicle.

[0051] The bench signal setting method of the present application is cleverly designed, dividing the torque range that the motor can achieve into several key torque sections; using the section points of the key torque sections and the known motor parameters, the size of each sinusoidal suspension load of the corresponding subframe is calculated; the distribution law of all motor torque values ​​in several key torque sections (that is, the different torque proportions of all motor torque values ​​in each key torque section) is used to calculate the distribution ratio of each sinusoidal suspension load of the subframe; using the small to obtain the large, the total number of cycles of all sinusoidal suspension loads within a set period of time is calculated based on the motor torque signal within a set time period; the distribution ratio of each sinusoidal suspension load is multiplied by the total number of cycles to obtain the number of cycles corresponding to each sinusoidal suspension load; the size of each sinusoidal suspension load and the number of cycles corresponding to each sinusoidal suspension load form a subframe bench signal, which can verify whether the durability of the subframe within the set period of time is qualified.

[0052] This solves the problem of overly general considerations of the suspension load on the subframe caused by motor torque during subframe durability testing. The bench signal setting method in this application directly obtains the suspension load at the subframe motor mounting location using historical vehicle data, establishing a correlation between the subframe bench test and the vehicle, making the subframe durability test structure more realistic and reliable.

[0053] In one embodiment, the set number of vehicles is n. In step S1, the torque range that the motor can achieve is divided into several key torque segments, and the different torque proportions of all motor torque values ​​in each key torque segment are calculated, including:

[0054] S11: Divide the torque value range that the motor can achieve into m normal torque segments, randomly extract the relevant signals of n1 vehicles (including accelerator pedal signals and motor torque signals), extract all motor torque values ​​of each vehicle, and calculate the different torque proportions of all motor torque values ​​of each vehicle in the m normal torque segments, and obtain the torque proportions of each of the n1 vehicles in the m normal torque segments.

[0055] S12: Perform segment aggregation to form m0 key torque segments, and obtain the torque proportion of each key torque segment.

[0056] This application selects n1 vehicles from n vehicles. Random selection can increase the credibility of the data.

[0057] Specifically, in Example A of the present application, n is equal to 2000, i.e., 2000 vehicles; n1 is equal to 694, and m is equal to 37. All motor torque values ​​of the first vehicle are extracted, and the different torque proportions of all motor torque values ​​of each vehicle in m common torque segments are calculated as shown in Table 1:

[0058] Table 1

[0059]

[0060] Furthermore, in Example A of the present application, the torque proportions of n1 vehicles in m normal torque sections are as shown in Table 2:

[0061] Table 2

[0062]

[0063] Specifically, the unit of torque in Table 1 and Table 2 is N·m.

[0064] Specifically, all a to b in the table represent torque values ​​T, where a≤T<b; for example, -110 to -100 represents -110≤T<-100.

[0065] The test bench signal setting method of the present application divides the torque value range that the motor can achieve into m ordinary torque segments, extracts all the motor torque values ​​of each vehicle, and calculates the different torque proportions of all the motor torque values ​​of each vehicle in the m ordinary torque segments, and obtains the torque proportions of n1 vehicles in the m ordinary torque segments; performs segment aggregation to form m0 key torque segments, and obtains the torque proportion of each key torque segment, which can obtain the distribution law of all motor torque values ​​in several key torque segments, and then obtain the distribution proportion law of each sinusoidal suspension load of the subframe.

[0066] Furthermore, in step S11, all motor torque values ​​of each vehicle are extracted, and different torque proportions of all motor torque values ​​of each vehicle in m common torque sections are calculated, including:

[0067] After extracting all motor torque values ​​of each vehicle, the arithmetic average method is used to calculate the different torque proportions of all motor torque values ​​in m common torque segments.

[0068] In Example A of this application, two of the 37 (i.e., m = 37) common torque ranges are between -110 and -100 N·m. Vehicle 1 has a total of 100,000 motor torque values, 11 of which fall within the range of -110 to -100 N·m. The arithmetic average indicates that the proportion of torque values ​​for Vehicle 1 within the range of -110 to -100 N·m is 11 / 100,000 = 0.011%. Similarly, the data in Table 2 is obtained.

[0069] Furthermore, in step S12, the segments are aggregated to form m0 key torque segments, including: when dividing the m0 key torque segments, the torque proportions of more than 80% of the n1 vehicles fall into the m0 key torque segments.

[0070] In Example A of the present application, after obtaining the data in Table 2, segment aggregation is performed to form 5 (i.e., m0=5) key torque segments, requiring the sum of the torque proportions of the two middle key torque segments to exceed 80%, and finally Table 3 is obtained.

[0071] Table 3

[0072] Critical torque range Torque ratio ＜-40 0.8％ ≥-40&＜20 49.1％ ≥20&＜80 47.3％ ≥80&＜150 2.6％ ≥150 0.2％

[0073] Specifically, from Table 2 to Table 3, first add each column in Table 2 and divide it by n1 to obtain the torque column proportion of each column in the torque segment. Then, according to the key torque segment of the column on the left side of Table 2, sum the torque column proportions of each column in Table 2 to obtain Table 3.

[0074] Specifically, ≥-40&<20 indicates that the torque value T is within the range of -40≤T<20.

[0075] The bench signal setting method of the present application forms two highly representative key torque sections, which will further form a highly representative sinusoidal suspension load in the subsequent period. Under such a sinusoidal suspension load, a correspondingly large number of cycles will be performed in the subsequent period. Such a sinusoidal suspension load and a large number of cycles can basically determine whether the subframe durability test is qualified, and can concentrate the test data and highlight the test results.

[0076] In one embodiment, in step S2, using the segment points of each key torque segment and known motor parameters, calculating each sinusoidal suspension load of the subframe where the motor is mounted corresponding to each key torque segment includes:

[0077] Merge the critical torque segment with the smallest segment point into the adjacent critical torque segment, that is, merge m0 critical torque segments into m0-1 critical torque segments, and sum the torque proportions of the two critical torque segments when merging. Set m0-1 load torque segments corresponding to the critical torque segments one by one, and the torque proportions of the m0-1 load torque segments correspond to the merged critical torque segments. Lower the set value of the smallest critical torque negative segment point in the m0 critical torque segments as the lower limit value of the load fixed torque of each load torque segment; use the largest positive segment point in the m ordinary torque segments as the load torque upper limit segment point of the maximum load torque segment; use the upper limit segment points of the remaining critical torque segments except the critical torque segment with the largest segment point in the merged m0-1 critical torque segments as the load torque upper limit segment points of the remaining load torque segments;

[0078] According to the load torque section and the known motor parameters, the sinusoidal suspension load of each section corresponding to the motor installation position of the subframe is calculated.

[0079] The test bench signal setting method of the present application first passes through the common torque section and then to the key torque section, and then obtains the load torque section through the key torque section, sets m0-1 load torque sections corresponding to the merged key torque sections, and the torque proportion of the m0-1 load torque sections corresponds to the merged m0-1 key torque sections, and obtains the torque proportion of the m0-1 load torque sections;

[0080] The smallest negative segment point of the key torque in the m0 key torque segments is lowered by a set value as the lower limit value of the load fixed torque of each load torque segment; the largest positive segment point in the m ordinary torque segments is used as the upper limit segment point of the load torque of the maximum load torque segment; the upper limit segment points of the remaining key torque segments except the key torque segment with the largest segment point in the merged m0-1 key torque segments are used as the upper limit segment points of the load torque of the remaining load torque segments, and each segment point of the m0-1 load torque segments is obtained; and then combined with the known motor parameters, the size and proportion distribution of the sinusoidal suspension load in each segment of the motor installation position of the subframe can be calculated to form the required bench signal.

[0081] In Example A of the present application, given Table 3, it specifically includes:

[0082] Merge the critical torque segment with the smallest segment point into the adjacent critical torque segment, that is, merge the two critical torque segments <-40 and ≥-40&<20 to form <20N·m, corresponding to the same load torque segment -100~20N·m, that is, there are a total of 5-1=4 load torque segments.

[0083] The smallest critical torque negative section point (i.e., <-40 N·m) in the five critical torque sections is adjusted down to the set value, down to -100 N·m, as the lower limit value of the load fixed torque in each load torque section.

[0084] The largest positive segment point (ie, >230 N·m) among the 37 (ie, m=37) normal torque segments is used as the load torque upper limit segment point of the maximum load torque segment.

[0085] The upper limit segment points of the remaining key torque segments (the remaining three key torque segments) except for the key torque segment with the largest segment point (the first column after the merger is <20 N·m) in the four merged key torque segments are used as the load torque upper limit segment points of the remaining load torque segments (the first segment, the second segment, and the third segment from the top to the bottom of the load torque segment), and the combination is combined to obtain Table 4.

[0086] Table 4

[0087]

[0088] In order to form a sinusoidal signal and cover as wide a range as possible, a value of -100 is taken, and then 150 is extended to 230 to form a load torque segment that covers all actual torque segments and has redundancy.

[0089] Furthermore, based on the load torque segments and known motor parameters, the sinusoidal suspension loads of each segment corresponding to the motor mounting position of the subframe are calculated, including:

[0090] Each load torque section has a load fixed torque lower limit value and a load torque upper limit section point;

[0091] The minimum load is calculated based on the lower limit of the load fixed torque combined with the known motor parameters, the maximum load is calculated based on the upper limit section point of the load torque combined with the known motor parameters, half of the difference between the maximum load and the minimum load is used as the amplitude of the sinusoidal suspension load, the maximum load minus the amplitude is used as the mean of the sinusoidal suspension load, and the set frequency is used as the frequency of the sinusoidal suspension load to obtain the sinusoidal suspension load of each section.

[0092] In Example A of the present application, given Table 4, it includes:

[0093] The minimum load is calculated based on the lower limit of the load fixed torque (i.e., -100 N·m) in combination with the known motor parameters (various structural dimensions). The maximum load is calculated based on the upper limit section points of the load torque (i.e., 20 N·m, 80 N·m, 150 N·m, and 230 N·m) in combination with the known motor parameters. Half of the difference between the maximum load and the minimum load is used as the amplitude of the sinusoidal suspension load (i.e., 2520, 3780, 5250, and 6928 in Table 5). The average of the sinusoidal suspension load is obtained by subtracting the amplitude from the maximum load (i.e., 1680, 420, -1050, and -2728 in Table 5). The frequency is set to 2 to 3 Hz, thus forming four sinusoidal suspension load signals.

[0094] Table 5

[0095]

[0096] Subsequently, four sinusoidal suspension load signals with a frequency of 2 to 3 Hz (1680±2520, 420±3780, -1050±5250 and -2728±6928, all in N) are added to the bench test signal.

[0097] In one embodiment, in step S3, based on the number of accelerator pedal depressions corresponding to the accelerator pedal signal within the set time period, the total number of cycles of all sinusoidal suspended loads within the set period of time is calculated, including:

[0098] Set the time period to L days, the number of years required to achieve 300,000 kilometers to 10 years, the total number of cycles to Z, and the number of vehicles to n. Randomly sample the accelerator pedal strokes of n2 vehicles. Calculate the cumulative percentage of pedal strokes from 0 to the set number of pedal strokes X at set intervals, rounding to 90%. This means that each vehicle has a 90% probability of pedaling the accelerator between 0 and X times. Randomly sampling data from n2 vehicles out of n vehicles enhances data credibility.

[0099] Let X be the number of times the accelerator pedal is depressed for each vehicle within L days, and calculate Z = X / L × 365 × 10. This Z corresponds to a durability of 300,000 kilometers. Generally, if the subframe meets the durability standard at 300,000 kilometers, then the subframe meets the durability standard.

[0100] Specifically, in Example A of the present application, the calculation of Z specifically includes:

[0101] The time period is set to 7 days (i.e., L=7), it is set that it takes 10 years for a private car to run 300,000 kilometers, the set number of vehicles is 2,000, and 694 vehicles are randomly selected. The cumulative proportion of the number of times the accelerator pedal is stepped on from 0 to the set number of times 4,680 is rounded to 90%, that is, 90% of the vehicles will step on the accelerator pedal 0 to 4,680 times within 7 days, that is, directly take X=4,680 for calculation, then Z=4,680 / 7×365×10=2.44 million.

[0102] The set number of vehicles is n, and n2 vehicles are randomly selected. n and n2 do not participate in the calculation.

[0103] Usually, for durability testing, only 300,000 kilometers of durability are required to be qualified, that is, the verified parts or vehicles are qualified.

[0104] The test bench signal setting method of the present application uses the small to see the big picture. A set time period is set as L days. L days are used to calculate the total number of cycles per year and then represent 300,000 kilometers as Z. The cumulative proportion from 0 to the set number of pedaling times X is calculated in sequence at set intervals and rounded to 90%. It is obtained that there is a 90% probability that each vehicle will step on the accelerator pedal 0 to X times. X is directly used for calculation to determine whether the subframe has passed the durability test corresponding to 300,000 kilometers.

[0105] Furthermore, after obtaining the total number of cycles Z, the total number of cycles is multiplied by the different torque proportions of the m0-1 load torque sections to obtain the number of cycles corresponding to each sinusoidal suspension load.

[0106] In Example A of the present application, given that Z and Table 5 are known, Table 6 is obtained through further calculation.

[0107] Table 6

[0108] Suspended load Number of cycles 1680±2520 1.22 million 420±3780 1.16 million -1050±5250 65,000 -2728±6928 0.05 million

[0109] In one embodiment, m is equal to 37, and the torque range achievable by the motor is divided into 37 common torque segments, namely <-120, -120 to -110, -110 to -100, -100 to -90, ... 210 to 220, 220 to 230, and >230; all in N·m; m0 is equal to 5, and the five key torque segments are <-40, -40 to 20, 20 to 80, 8 to 150, and ≥150; and the five load torque segments are -100 to 20, -100 to 80, -100 to 150, and -100 to 230. The above data are all the data in Example A of this application.

[0110] The present application also discloses a test method using the above-mentioned bench signal setting method, using the subframe bench signal to perform a subframe durability test. When the cycle is completed, if the subframe is not cracked, the subframe is qualified; otherwise, it is unqualified.

[0111] Specifically, the four sinusoidal signals in Table 6 are cycled a corresponding number of times. When the final cycle is completed, if the subframe is not cracked, it means that the subframe has qualified for the durability of 300,000 kilometers and meets the standard requirements.

[0112] This test method directly obtains the suspension load at the subframe motor mounting point using vehicle data, establishing a correlation between the subframe bench test and the vehicle, making the subframe durability test structure more realistic and reliable. The key technical point of this application is to use the number of pedal strokes and torque distribution at the vehicle end to obtain the suspension load at the subframe mounting point.

[0113] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0114] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any 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 comprising 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, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0115] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A bench signal setting method for a subframe durability test, characterized in that: The following steps are involved: The accelerator pedal signals and motor torque signals of a set number of vehicles within a set time period are exported from an existing background test history database. The motor torque value is obtained based on the motor torque signal, the torque value range that the motor can achieve is divided into several key torque segments, and the different torque proportions of all motor torque values ​​within each key torque segment are calculated. Calculate the sinusoidal suspension loads of the subframe on which the motor is mounted, corresponding to each key torque segment, using the segment points of each key torque segment and known motor parameters; Based on the number of accelerator pedal depressions corresponding to the accelerator pedal signal within a set time period, the total number of cycles of all sinusoidal mount loads within a set period of time is calculated, and the total number of cycles is multiplied by the different torque proportions to obtain the number of cycles corresponding to each sinusoidal mount load; the size of each sinusoidal mount load and the number of cycles corresponding to each sinusoidal mount load form a subframe bench signal.

2. The bench signal setting method for a subframe durability test according to claim 1, characterized in that: The number of vehicles is set to n. The torque range that the motor can achieve is divided into several key torque segments, and the different torque proportions of all motor torque values ​​in each key torque segment are calculated, including: Divide the achievable torque range of the motor into m common torque segments, randomly sample the relevant signals of n1 vehicles, extract all the motor torque values ​​of each vehicle, and calculate the different torque proportions of all the motor torque values ​​of each vehicle within the m common torque segments, thus obtaining the torque proportions of each of the n1 vehicles within the m common torque segments; The segments are aggregated to form m0 key torque segments, and the torque proportion of each key torque segment is obtained.

3. The bench signal setting method for a subframe durability test according to claim 2, characterized in that: The method of extracting all motor torque values ​​of each vehicle and counting the torque proportion of each motor torque value in m common torque sections includes: After extracting all motor torque values ​​of each vehicle, the arithmetic average method is used to calculate the different torque proportions of all motor torque values ​​in m common torque segments.

4. The bench signal setting method for a subframe durability test according to claim 3, characterized in that: The segment aggregation is performed to form m0 key torque segments, including: When dividing the m0 key torque segments, the torque proportions of more than 80% of the n1 vehicles fall into the m0 key torque segments.

5. The bench signal setting method for a subframe durability test according to claim 2, characterized in that: The method of calculating the respective sinusoidal suspension loads of the subframe on which the motor is mounted corresponding to each key torque segment by using the segment points of each key torque segment and known motor parameters comprises: Merge a critical torque segment with the smallest segment point into an adjacent critical torque segment, set m0-1 load torque segments corresponding to the critical torque segments one by one, and the torque proportion of the m0-1 load torque segments corresponds to each key torque segment after the merger; adjust the smallest critical torque negative segment point in the m0 key torque segments down to a set value, as the load fixed torque lower limit value of each load torque segment; use the largest positive segment point in the m common torque segments as the load torque upper limit segment point of the maximum load torque segment; use the upper limit segment points of the remaining key torque segments except the largest and smallest in the merged m0-1 key torque segments as the load torque upper limit segment points of the remaining load torque segments; Based on the m0-1 load torque sections and the known motor parameters, the sinusoidal suspension loads in each section corresponding to the motor installation position of the subframe are calculated.

6. The bench signal setting method for a subframe durability test according to claim 5, characterized in that: Based on the load torque segments and known motor parameters, the sinusoidal suspension loads in each segment corresponding to the motor installation position on the subframe are calculated, including: Each load torque section has a load fixed torque lower limit value and a load torque upper limit section point; In each load torque section, the minimum load is calculated based on the lower limit value of the load fixed torque combined with the known motor parameters, and the maximum load is calculated based on the upper limit section point of the load torque combined with the known motor parameters. Half of the difference between the maximum load and the minimum load is used as the amplitude of the sinusoidal suspension load, and the maximum load minus the amplitude is used as the mean value of the sinusoidal suspension load. The set frequency is used as the frequency of the sinusoidal suspension load to obtain the sinusoidal suspension load of each section.

7. The bench signal setting method for a subframe durability test according to claim 5, characterized in that: The calculating of the total number of cycles of all sinusoidal suspended loads within a set period of time based on the number of accelerator pedal depressions corresponding to the accelerator pedal signal within a set time period includes: The time period is set to L days, the set period is set to 10 years, and the total number of cycles is Z. The set number of vehicles is n. The number of accelerator pedal strokes of n2 vehicles is randomly selected. The cumulative proportion from 0 to the set number of pedal strokes X is calculated in sequence at a set interval, rounded to 90%, and the probability that each vehicle will step on the accelerator pedal 0-X times is 90%. X is used as the number of accelerator pedal strokes for each vehicle in L days, and Z is calculated as (X / L)×365×10.

8. The bench signal setting method for a subframe durability test according to claim 7, characterized in that: After obtaining the total number of cycles Z, the total number of cycles is multiplied by the different torque proportions of the m0-1 load torque sections to obtain the number of cycles corresponding to each sinusoidal suspension load.

9. The bench signal setting method for a subframe durability test according to claim 5, characterized in that: The m is equal to 37, and the torque value range that the motor can achieve is divided into 37 common torque segments, which are respectively <-120, -120~-110, -110~-100, -100~-90, ... 210~220, 220~230, and >230; the unit is N·m; the m0 is equal to 5, and the five key torque segments are respectively <-40, -40~20, 20~80, 80~150 and ≥150; the four load torque segments are respectively -100~20, -100~80, -100~150, and -100~230.

10. A test method using the test bench signal setting method according to any one of claims 1 to 9, characterized in that: A subframe durability test is performed using the subframe bench signal. When the cycle is completed, if the subframe is not cracked, the subframe passes; otherwise, it fails.

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