A method and electronic device for generating load spectrum of differential case durability test

Abstract

The present application relates to a method for generating a differential housing durability test load spectrum and an electronic device, and relates to the field of vehicle engineering technology. The method first obtains a theoretical torque graded load spectrum and a theoretical rain flow load spectrum, then obtains the maximum differential housing damage value when the theoretical torque graded load spectrum is used as a load input, and the maximum differential housing damage value when the theoretical rain flow load spectrum is used as a load input, calculates the actual torque graded load spectrum and the actual rain flow load spectrum, and finally determines whether the corresponding maximum actual differential housing damage value when the actual torque graded load spectrum and the actual rain flow load spectrum are used as load inputs respectively satisfies not less than the maximum differential housing damage value when the corresponding theoretical load spectrum is used as load input. If at least one is not satisfied, the differential housing durability test load spectrum is obtained after adjustment until both are satisfied. The method provided by the present application improves the efficiency and accuracy of generating a differential housing durability test load spectrum, and reduces the test cost.

Description

Technical Field

[0001] The present application relates to the field of vehicle engineering technology, and in particular to a method for generating a differential case durability test load spectrum and an electronic device. Background Art

[0002] At present, the differential is one of the most important components in the automobile transmission system, among which the differential housing is the main structure of the differential. The differential housing acts as a skeleton to combine the differential gear, half-shaft gear, cross shaft and other components together, and is connected to the main reduction gear on the outside to ensure that the gearbox input torque is transmitted through the differential. The fatigue durability of the differential housing directly affects the durability and safety of the vehicle, so it is very important to obtain a reliable differential housing durability test load spectrum and formulate a scientific test method, but this method is costly and cannot meet the requirements of the design time cycle.

[0003] In the related art, there are two main methods for obtaining the differential case durability test load spectrum. The first is to conduct an assessment based on the fixed working conditions defined in QC / T 568.2. The second is to conduct whole vehicle or gearbox measurements, measure the differential case load spectrum, and scale it to obtain the durability load spectrum.

[0004] However, the fixed working conditions in the first method mentioned above have no correlation with the vehicle parameters and customer usage conditions, and the generated load spectrum is quite different from the fatigue damage caused by the actual load. The second method has high test costs and cannot meet the requirements of the design time cycle. Summary of the invention

[0005] The embodiment of the present application provides a differential case durability test load spectrum generation method and electronic equipment to solve the problems of low efficiency in obtaining the differential case durability test load spectrum, high test cost and large test error rate in the related art.

[0006] In a first aspect, a method for generating a differential case durability test load spectrum is provided, the steps comprising:

[0007] Establish a vehicle dynamics simulation model to obtain theoretical torque graded load spectrum and theoretical rain flow load spectrum;

[0008] Establishing a finite element model of a differential housing, obtaining a maximum differential housing damage value when the theoretical torque graded load spectrum is used as a load input, and a maximum differential housing damage value when the theoretical rain flow load spectrum is used as a load input;

[0009] Performing a gearbox bench test, respectively obtaining an input torque-time function and an input speed-time function, and obtaining a speed change test load spectrum according to the input torque-time function and the input speed-time function, and respectively calculating an actual torque graded load spectrum and an actual rain flow load spectrum according to the speed change test load spectrum;

[0010] Determine whether the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input satisfies or is not less than the maximum differential case damage value when the theoretical torque graded load spectrum is used as the load input, and whether the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input satisfies or is not less than the maximum differential case damage value when the theoretical rain flow load spectrum is used as the load input, and if at least one is not satisfied, respectively adjust the values ​​of the corresponding characteristic points on the input torque-time function and the input speed-time function until both are satisfied;

[0011] The differential case durability test load spectrum is obtained according to the adjusted input torque-time function and input speed-time function.

[0012] In some embodiments, the step of establishing a vehicle dynamics simulation model and obtaining a theoretical torque graded load spectrum and a theoretical rain flow load spectrum includes:

[0013] According to the vehicle parameters, engine parameters and transmission parameters, the driving condition module, driving terrain module, engine module, driver module, transmission module and vehicle and tire module are built respectively to establish a vehicle dynamics simulation model;

[0014] Selecting a gearbox durability driving condition, and performing a whole vehicle simulation using the whole vehicle dynamics simulation model according to the operating condition parameters and road parameters corresponding to the gearbox durability driving condition;

[0015] The dynamic load spectrum of the whole vehicle is calculated based on the data of the whole vehicle simulation, the dynamic load spectrum of the gearbox main reduction gear is obtained based on the dynamic load spectrum of the whole vehicle, and the theoretical torque graded load spectrum and the theoretical rain flow load spectrum are calculated based on the dynamic load spectrum of the gearbox main reduction gear.

[0016] In some embodiments, the step of calculating the theoretical torque graded load spectrum according to the dynamic load spectrum of the gearbox final reduction gear comprises:

[0017] Acquire the input torque time history and speed time history of the gearbox main reduction gear according to the dynamic load spectrum of the gearbox main reduction gear;

[0018] The number of rotations of the main reduction gear corresponding to each torque level is calculated according to the input torque time history and the speed time history, and the theoretical torque graded load spectrum is obtained according to the number of rotations.

[0019] In some embodiments, the step of calculating the theoretical rain flow load spectrum according to the dynamic load spectrum of the gearbox final reduction gear comprises:

[0020] Obtaining the time history of the load of the main reduction gear according to the dynamic load spectrum of the main reduction gear of the gearbox;

[0021] The theoretical rain flow load spectrum of the gearbox main reduction gear is obtained by calculating the load time history of the main reduction gear according to the rain flow counting method.

[0022] In some embodiments, the gearbox bench test is performed to obtain the input torque-time function and the input speed-time function respectively, including:

[0023] Determine the peak torque Tmax that the gearbox can reach in the first gear, and the minimum torque Tmin of the gearbox, and determine the minimum speed Nmin of the test bench input and the maximum speed Nmax of the test bench input;

[0024] Corresponding tests are performed on a gearbox test bench according to the minimum torque Tmin and the peak torque Tmax to obtain the input torque-time function, and corresponding tests are performed on a gearbox test bench according to the minimum speed Nmin and the maximum speed Nmax to obtain the input speed-time function.

[0025] In some embodiments, the corresponding test is performed on a gearbox test bench according to the minimum torque Tmin and the peak torque Tmax to obtain the input torque-time function, including:

[0026] The initial value of the input torque is the minimum torque Tmin, and after a preset time, the input torque increases to the peak torque Tmax at the maximum acceleration of the torque increase, and then the torque decreases to the minimum torque Tmin, so as to generate the input torque-time function;

[0027] The input torque-time function is subjected to a first-order low-pass filter.

[0028] In some embodiments, performing corresponding tests on a gearbox test bench according to the minimum speed Nmin and the maximum speed Nmax to obtain the input speed-time function includes:

[0029] When the minimum torque Tmin is greater than 0, before the input torque reaches the minimum torque Tmin, the input speed is increased to the maximum speed Nmax at a constant acceleration, and then the input speed is decreased to the minimum speed Nmin at the maximum deceleration of the test bench, so as to generate the input speed-time function;

[0030] When the minimum torque Tmin is less than 0, before the input torque reaches 0, the input speed is increased to the maximum speed Nmax at a constant acceleration, and then the input speed is decreased to the minimum speed Nmin at the maximum deceleration of the test bench to generate the input speed-time function.

[0031] In some embodiments, a plurality of corresponding characteristic points for generating the input torque-time function and the input speed-time function are respectively obtained according to the gearbox bench test;

[0032] Input the acquired multiple characteristic points into matlab software, and automatically calculate the maximum actual differential case damage value when the actual torque graded load spectrum corresponding to the speed change test load spectrum corresponding to the characteristic points is used as the load input, and the maximum actual differential case damage value when the actual rain flow load spectrum corresponding to the speed change test load spectrum corresponding to the characteristic points is used as the load input according to the matlab software and the multiple characteristic points;

[0033] The numerical values ​​of the characteristic points are adjusted according to the magnitudes of the two largest actual differential case damage values, and automatic iterative calculation is performed in combination with the gearbox bench test.

[0034] In some embodiments, the whole vehicle dynamics simulation model is established in matlab software or simulink software.

[0035] In a second aspect, an electronic device for generating a differential case durability test load spectrum is provided, comprising: a processor and a memory, wherein the processor executes a code in the memory to implement any one of the above methods.

[0036] The beneficial effects of the technical solution provided by this application include:

[0037] The embodiment of the present application provides a method for generating a differential case durability test load spectrum. After establishing a vehicle dynamics simulation model to obtain a theoretical torque graded load spectrum and a theoretical rain flow load spectrum, a differential case finite element model is then established to obtain the maximum differential case damage value when the theoretical torque graded load spectrum is used as a load input, and the maximum differential case damage value when the theoretical rain flow load spectrum is used as a load input. Then, a gearbox bench test is performed to calculate the actual torque graded load spectrum and the actual rain flow load spectrum. Finally, it is determined whether the corresponding maximum actual differential case damage value when the actual torque graded load spectrum and the actual rain flow load spectrum are used as load inputs respectively satisfies the condition of being not less than the maximum differential case damage value when the corresponding theoretical load spectrum is used as load input. If at least one of them is not satisfied, the values ​​of the corresponding characteristic points on the input torque-time function and the input speed-time function are adjusted respectively until both conditions are satisfied to obtain the differential case durability test load spectrum. Therefore, the use of this method greatly improves the efficiency of generating the differential case durability test load spectrum, and also reduces the test cost, so that the differential case durability test load spectrum is as close as possible to the actual durability load spectrum, thereby improving the accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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.

[0039] Figure 1 A schematic flow chart of a method for generating a differential case durability test load spectrum according to an embodiment of the present application;

[0040] Figure 2 A schematic diagram of a flow chart of a differential case durability test load spectrum generation method provided in an embodiment of the present application for obtaining a theoretical torque graded load spectrum and a theoretical rain flow load spectrum;

[0041] Figure 3 A schematic diagram of a flow chart of a method for generating a differential case durability test load spectrum provided in an embodiment of the present application, which calculates a theoretical torque graded load spectrum based on a dynamic load spectrum of a gearbox main reduction gear;

[0042] Figure 4 The differential case durability test load spectrum generation method provided in the embodiment of the present application is a flow chart of obtaining the theoretical rain flow load spectrum based on the dynamic load spectrum of the gearbox main reduction gear. DETAILED DESCRIPTION

[0043] 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.

[0044] The embodiment of the present application provides a method for generating a differential case durability test load spectrum, which can solve the problems of low efficiency in obtaining the differential case durability test load spectrum, high test cost and large test error rate in the related art.

[0045] See also Figure 1 As shown, the steps of the differential case durability test load spectrum generation method mainly include:

[0046] Establish a vehicle dynamics simulation model to obtain theoretical torque graded load spectrum and theoretical rain flow load spectrum;

[0047] A finite element model of the differential housing is established to obtain the maximum differential housing damage value when the theoretical torque graded load spectrum is used as the load input, and the maximum differential housing damage value when the theoretical rain flow load spectrum is used as the load input;

[0048] Perform a gearbox bench test to obtain input torque-time function and input speed-time function respectively, obtain a speed change test load spectrum according to the input torque-time function and the input speed-time function, and calculate an actual torque graded load spectrum and an actual rain flow load spectrum according to the speed change test load spectrum;

[0049] Determine whether the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input satisfies or is not less than the maximum differential case damage value when the theoretical torque graded load spectrum is used as the load input, and whether the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input satisfies or is not less than the maximum differential case damage value when the theoretical rain flow load spectrum is used as the load input, if at least one is not satisfied, respectively adjust the values ​​of the corresponding characteristic points on the input torque-time function and the input speed-time function until both are satisfied;

[0050] The differential case durability test load spectrum is obtained according to the adjusted input torque-time function and input speed-time function.

[0051] Specifically, the differential case durability test load spectrum generation method uses an established vehicle dynamics simulation model in combination with corresponding driving conditions, and quickly and accurately generates a dynamic load spectrum of the gearbox main reduction gear by defining vehicle parameters, engine parameters, gearbox parameters and other data. The method has the advantages of being strongly associated with vehicle parameters, engine parameters, gearbox parameters, and being strongly associated with corresponding durability driving conditions. In addition, the method satisfies both the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input and the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input, which greatly improves the efficiency of generating the differential case durability test load spectrum, reduces the test cost, and makes the differential case durability test load spectrum as close as possible to the actual durability load spectrum, thereby improving the accuracy.

[0052] For further information, see Figure 2 As shown, the steps of establishing a vehicle dynamics simulation model and obtaining a theoretical torque graded load spectrum and a theoretical rain flow load spectrum include:

[0053] According to the vehicle parameters, engine parameters and transmission parameters, the driving condition module, driving terrain module, engine module, driver module, transmission module and vehicle and tire module are built respectively to establish a vehicle dynamics simulation model;

[0054] Select the gearbox durability driving condition, and use the vehicle dynamics simulation model to perform vehicle simulation based on the operating parameters and road parameters corresponding to the gearbox durability driving condition;

[0055] The dynamic load spectrum of the whole vehicle is calculated based on the data of the whole vehicle simulation, the dynamic load spectrum of the gearbox main reduction gear is obtained based on the dynamic load spectrum of the whole vehicle, and the theoretical torque graded load spectrum and the theoretical rain flow load spectrum are calculated based on the dynamic load spectrum of the gearbox main reduction gear.

[0056] Specifically, the vehicle dynamics simulation model includes a driving condition module, a driving terrain module, an engine module, a driver module, a gearbox module, and a vehicle and tire module. Detailed vehicle parameters, engine parameters, and gearbox parameters are defined in the vehicle dynamics simulation model, including driving mode, vehicle unloaded mass, vehicle fully loaded mass, wheelbase, track width, vehicle center of gravity height, distance between center of gravity and front and rear axles, wheel dynamic radius, tire rolling friction coefficient, tire sliding friction coefficient, wind resistance coefficient, frontal area, engine external characteristic curve, gearbox ratio, and gearbox transmission efficiency, etc. In the vehicle dynamics simulation model, a gearbox durable driving condition is selected, which represents 90% of customers driving 240,000 kilometers. Subsequently, the vehicle dynamics simulation is performed to calculate the vehicle dynamic load spectrum, and then the dynamic load spectrum of the gearbox main reduction gear is obtained, including vehicle speed, engine torque, engine speed, gearbox input shaft speed, accelerator pedal depth, brake pedal depth, etc.

[0057] For further information, see Figure 3 As shown in the figure, the theoretical torque graded load spectrum is calculated based on the dynamic load spectrum of the gearbox main reduction gear, including:

[0058] According to the dynamic load spectrum of the gearbox main reduction gear, the input torque time history and speed time history of the gearbox main reduction gear are obtained;

[0059] The number of rotations of the main reduction gear corresponding to each torque level is calculated based on the input torque time history and the speed time history, and the torque graded load spectrum is obtained based on the number of rotations.

[0060] Specifically, for the gearbox's main reduction gear, each tooth on the gear will be subjected to a load cycle from zero to maximum and then back to zero for each rotation of the main reduction gear. If the gear rotates n times, each tooth on the main reduction gear will experience n cycles of alternating loads. If the torque amplitude on the main reduction gear is divided into several intervals, then at the torque level Ti, the number of rotations ni of the main reduction gear can be calculated by the following formula:

[0061]

[0062] Among them, in formula (1), n(t) is the function of the speed of the main reduction gear changing with time, ni is the number of rotations of the main reduction gear under the i-th level torque, Δt1, Δt2, Δt3 and Δtj are the corresponding time periods under the torque level Ti. For the dynamic load spectrum of the main reduction gear of the gearbox obtained by simulation, the number of rotations of the main reduction gear corresponding to each torque level is obtained by using formula (1), and finally the theoretical torque graded load spectrum can be obtained.

[0063] For further information, see Figure 4 As shown, the steps of calculating the theoretical rain flow load spectrum according to the dynamic load spectrum of the gearbox main reduction gear include:

[0064] Obtain the time history of the load on the main reduction gear according to the dynamic load spectrum of the main reduction gear of the gearbox;

[0065] The theoretical rain flow load spectrum of the gearbox main reduction gear is obtained by calculating the load time history of the main reduction gear according to the rain flow counting method.

[0066] Specifically, the counting method for generating the theoretical rain flow load spectrum needs to follow the basic counting rules: Step 1: The rain flow flows down the slope from the inside of the peak position of the main reduction gear load time history; Step 2: The rain flow starts to flow from a certain peak point, and stops when it encounters a peak value larger than its initial peak value; Step 3: When the rain flow encounters the rain flow flowing down from above, it must stop flowing; Step 4: Take out all the full cycles and record the amplitude of each cycle; Step 5: Equivalently treat the divergent convergent load time history left after the first stage counting as a convergent divergent load time history, and perform the second stage rain flow counting. The total number of the final counting cycles is equal to the sum of the counting cycles of the two counting stages. Therefore, the theoretical rain flow load spectrum of the gearbox main reduction gear is obtained by using the rain flow counting method for the simulated main reduction gear load time history.

[0067] Furthermore, the steps of performing a gearbox bench test to obtain the input torque-time function and the input speed-time function respectively include:

[0068] According to the gearbox type, determine the peak torque Tmax that the gearbox can reach in the first gear and the minimum torque Tmin of the gearbox. According to the engine type matched with the gearbox, determine the minimum speed Nmin and the maximum speed Nmax of the test bench input.

[0069] Corresponding tests are carried out on the gearbox test bench according to the minimum torque Tmin and the peak torque Tmax to obtain the input torque-time function, and corresponding tests are carried out on the gearbox test bench according to the minimum speed Nmin and the maximum speed Nmax to obtain the input speed-time function.

[0070] Specifically, in the process of generating the transmission test load spectrum by performing the gearbox bench test, the boundary conditions need to be determined first, that is, the peak torque Tmax that the gearbox can reach in the first gear and the minimum torque Tmin of the gearbox, where the minimum torque Tmin needs to be set according to the actual test requirements. Then, the minimum speed Nmin and the maximum speed Nmax of the engine are determined according to the engine curve.

[0071] Furthermore, corresponding tests are carried out on a gearbox test bench according to the minimum torque Tmin and the peak torque Tmax to obtain the input torque-time function. The steps are as follows: first, the initial value of the input torque is the minimum torque Tmin, and after a preset time, the torque is increased to the peak torque Tmax at the maximum acceleration of the torque increase, and then the torque is reduced to the minimum torque Tmin to generate an input torque-time function; and then the input torque-time function is subjected to a first-order low-pass filter. After filtering, the input torque-time function curve will be smoother and easier to implement on the test bench.

[0072] Further, the steps of performing corresponding tests on a gearbox test bench according to the minimum speed Nmin and the maximum speed Nmax to obtain an input speed-time function include:

[0073] When the minimum torque Tmin is greater than 0, before the input torque reaches the minimum torque Tmin, the input speed is increased to the maximum speed Nmax at a constant acceleration, and then the input speed is decreased to the minimum speed Nmin at the maximum deceleration of the test bench to generate an input speed-time function;

[0074] When the minimum torque Tmin is less than 0, before the input torque reaches 0, the input speed is increased to the maximum speed Nmax at a constant acceleration, and then the input speed is decreased to the minimum speed Nmin at the maximum deceleration of the test bench to generate an input speed-time function.

[0075] Among them, in the actual gearbox bench test, after obtaining the input torque-time function and the input speed-time function respectively, the speed change test load spectrum can be obtained according to the input torque-time function and the input speed-time function. Here, according to the obtained speed change test load spectrum, the method of calculating the theoretical torque graded load spectrum and the theoretical rain flow load spectrum according to the dynamic load spectrum of the transmission main reduction gear during simulation is adopted to calculate the actual torque graded load spectrum and the actual rain flow load spectrum.

[0076] Furthermore, the method further comprises the following steps:

[0077] According to the gearbox bench test, a plurality of corresponding characteristic points for generating an input torque-time function and an input speed-time function are obtained respectively;

[0078] Input the acquired multiple characteristic points into the matlab software, and automatically calculate the maximum actual differential case damage value when the actual torque graded load spectrum corresponding to the speed change test load spectrum corresponding to the characteristic point is used as the load input, and the maximum actual differential case damage value when the actual rain flow load spectrum corresponding to the speed change test load spectrum corresponding to the characteristic point is used as the load input;

[0079] The numerical values ​​of the characteristic points are adjusted according to the magnitudes of the two largest actual differential case damage values, and automatic iterative calculations are performed in combination with the gearbox bench test.

[0080] Specifically, in order to further improve the efficiency of load spectrum production, a MATLAB applet software was developed. It only needs to set several characteristic points of the input torque-time function and the input speed-time function, and then the input torque-time function and the input speed-time function can be generated after interpolation and filtering of these characteristic points through the MATLAB program. The speed change test load spectrum is automatically generated according to the input torque-time function and the input speed-time function. Similarly, the actual torque graded load spectrum and the actual rain flow load spectrum are automatically generated according to the speed change test load spectrum. Finally, the maximum actual differential case damage value when the actual torque graded load spectrum is used as the load input, and the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input are automatically calculated. Generally, it is required that the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input is not less than the maximum differential case damage value when the theoretical torque graded load spectrum is used as the load input, and the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input is not less than the maximum differential case damage value when the theoretical rain flow load spectrum is used as the load input. In order to ensure the quality of the vehicle, preferably, the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input, and the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input are multiples of the differential case damage value obtained during the corresponding simulation. Here, the multiple is greater than 1 and can be determined based on actual experiments. In the process of manual or automatic adjustment of characteristic points, the error of the automatic iteration structure is allowed to be within 5%.

[0081] Furthermore, after obtaining the final differential case durability test load spectrum, the following steps are also included:

[0082] Prepare no less than 2 sample boxes, and conduct tests according to the obtained differential case durability test load spectrum. After the test, check the status of the differential. If the differential case has no deformation or cracks, and the screws and gear rings connecting the differential case are not loose, then the differential case durability test of the sample box is determined to be qualified. If all the differential case durability tests of the sample boxes are qualified, it can be concluded that the durability of the differential case can meet the life requirements within the warranty mileage of the vehicle.

[0083] Furthermore, a whole vehicle dynamics simulation model is established in matlab software or simulink software. Specifically, the whole vehicle dynamics simulation model is a simulation system established in matlab software or simulink tools. In order to improve the efficiency of load spectrum production, matlab software is also used for automatic iterative calculation, which improves the efficiency of test load spectrum generation and shortens the test cycle.

[0084] The present application also provides an electronic device for generating a differential case durability test load spectrum, which includes a processor and a memory, and the processor executes the code in the memory to implement the following method:

[0085] Establish a vehicle dynamics simulation model to obtain theoretical torque graded load spectrum and theoretical rain flow load spectrum;

[0086] A finite element model of the differential housing is established to obtain the maximum differential housing damage value when the theoretical torque graded load spectrum is used as the load input, and the maximum differential housing damage value when the theoretical rain flow load spectrum is used as the load input;

[0087] Perform a gearbox bench test to obtain input torque-time function and input speed-time function respectively, obtain a speed change test load spectrum according to the input torque-time function and the input speed-time function, and calculate an actual torque graded load spectrum and an actual rain flow load spectrum according to the speed change test load spectrum;

[0088] Determine whether the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input satisfies or is not less than the maximum differential case damage value when the theoretical torque graded load spectrum is used as the load input, and whether the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input satisfies or is not less than the maximum differential case damage value when the theoretical rain flow load spectrum is used as the load input, if at least one is not satisfied, respectively adjust the values ​​of the corresponding characteristic points on the input torque-time function and the input speed-time function until both are satisfied;

[0089] The differential case durability test load spectrum is obtained according to the adjusted input torque-time function and input speed-time function.

[0090] Preferably, the processor executing the code in the memory can also implement other steps in the differential case durability test load spectrum generating method.

[0091] In the description of the present application, it should be noted that the terms "upper", "lower", etc. 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 the present application and simplifying the description, rather than indicating or implying 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 the present 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 it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0092] 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.

[0093] The above description 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 generating a load spectrum for a differential case durability test, It is characterized in that It includes: Establish a vehicle dynamics simulation model to obtain theoretical torque graded load spectrum and theoretical rain flow load spectrum; Establishing a finite element model of a differential housing, obtaining a maximum differential housing damage value when the theoretical torque graded load spectrum is used as a load input, and a maximum differential housing damage value when the theoretical rain flow load spectrum is used as a load input; Performing a gearbox bench test, respectively obtaining an input torque-time function and an input speed-time function, and obtaining a speed change test load spectrum according to the input torque-time function and the input speed-time function, and respectively calculating an actual torque graded load spectrum and an actual rain flow load spectrum according to the speed change test load spectrum; Determine whether the maximum actual differential case damage value corresponding to the actual torque graded load spectrum as the load input satisfies or is not less than the maximum differential case damage value when the theoretical torque graded load spectrum is used as the load input, and whether the maximum actual differential case damage value when the actual rain flow load spectrum is used as the load input satisfies or is not less than the maximum differential case damage value when the theoretical rain flow load spectrum is used as the load input, and if at least one is not satisfied, respectively adjust the values ​​of the corresponding characteristic points on the input torque-time function and the input speed-time function until both are satisfied; Obtaining a differential case durability test load spectrum according to the adjusted input torque-time function and input speed-time function; Obtaining the input torque time history and speed time history of the gearbox main reduction gear according to the dynamic load spectrum of the gearbox main reduction gear; The number of rotations of the main reduction gear corresponding to each torque level is calculated according to the input torque time history and the speed time history, and the theoretical torque graded load spectrum is obtained according to the number of rotations; Obtaining the time history of the load of the main reduction gear according to the dynamic load spectrum of the main reduction gear of the gearbox; The theoretical rain flow load spectrum of the gearbox main reduction gear is obtained by calculating the load time history of the main reduction gear according to the rain flow counting method.

2. A method for generating a differential case durability test load spectrum according to claim 1, It is characterized in that The method of establishing a vehicle dynamics simulation model and obtaining a theoretical torque graded load spectrum and a theoretical rain flow load spectrum includes: According to the vehicle parameters, engine parameters and transmission parameters, the driving condition module, driving terrain module, engine module, driver module, transmission module and vehicle and tire module are built respectively to establish a vehicle dynamics simulation model; Selecting a gearbox durability driving condition, and performing a whole vehicle simulation using the whole vehicle dynamics simulation model according to the operating condition parameters and road parameters corresponding to the gearbox durability driving condition; The dynamic load spectrum of the whole vehicle is calculated based on the data of the whole vehicle simulation, the dynamic load spectrum of the gearbox main reduction gear is obtained based on the dynamic load spectrum of the whole vehicle, and the theoretical torque graded load spectrum and the theoretical rain flow load spectrum are calculated based on the dynamic load spectrum of the gearbox main reduction gear.

3. A method for generating a differential case durability test load spectrum as claimed in claim 1, It is characterized in that The gearbox bench test is performed to obtain the input torque-time function and the input speed-time function respectively, including: Determine the peak torque Tmax that the gearbox can reach in the first gear, and the minimum torque Tmin of the gearbox, and determine the minimum speed Nmin of the bench input and the maximum speed Nmax of the bench input; Corresponding tests are performed on a gearbox test bench according to the minimum torque Tmin and the peak torque Tmax to obtain the input torque-time function, and corresponding tests are performed on a gearbox test bench according to the minimum speed Nmin and the maximum speed Nmax to obtain the input speed-time function.

4. A method for generating a differential case durability test load spectrum as claimed in claim 3, It is characterized in that The corresponding test is performed on a gearbox test bench according to the minimum torque Tmin and the peak torque Tmax to obtain the input torque-time function, including: The initial value of the input torque is the minimum torque Tmin, and after a preset time, the input torque increases to the peak torque Tmax at the maximum acceleration of the torque increase, and then the torque decreases to the minimum torque Tmin, so as to generate the input torque-time function; The input torque-time function is subjected to a first-order low-pass filter.

5. A method for generating a differential case durability test load spectrum as claimed in claim 4, It is characterized in that The corresponding test is performed on a gearbox test bench according to the minimum speed Nmin and the maximum speed Nmax to obtain the input speed-time function, including: When the minimum torque Tmin is greater than 0, before the input torque reaches the minimum torque Tmin, the input speed is increased to the maximum speed Nmax at a constant acceleration, and then the input speed is decreased to the minimum speed Nmin at the maximum deceleration of the test bench, so as to generate the input speed-time function; When the minimum torque Tmin is less than 0, before the input torque reaches 0, the input speed is increased to the maximum speed Nmax at a constant acceleration, and then the input speed is decreased to the minimum speed Nmin at the maximum deceleration of the test bench to generate the input speed-time function.

6. A method for generating a differential case durability test load spectrum as claimed in claim 1, Features: According to the gearbox bench test, a plurality of corresponding characteristic points for generating the input torque-time function and the input speed-time function are respectively obtained; Input the acquired multiple characteristic points into matlab software, and automatically calculate the maximum actual differential case damage value when the actual torque graded load spectrum corresponding to the speed change test load spectrum corresponding to the characteristic points is used as the load input, and the maximum actual differential case damage value when the actual rain flow load spectrum corresponding to the speed change test load spectrum corresponding to the characteristic points is used as the load input according to the matlab software and the multiple characteristic points; The numerical values ​​of the characteristic points are adjusted according to the magnitudes of the two largest actual differential case damage values, and automatic iterative calculation is performed in combination with the gearbox bench test.

7. A method for generating a differential case durability test load spectrum as claimed in claim 1, Features: The whole vehicle dynamics simulation model is established in matlab software or simulink software.

8. An electronic device for generating a differential case durability test load spectrum, Features: The method comprises a processor and a memory, wherein the processor executes the code in the memory to implement the method according to any one of claims 1 to 7.

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