CN115587482A - Durable load spectrum generation method and system for gearbox of two-gear electric off-road vehicle - Google Patents

Abstract

The invention discloses a method and a system for generating a durable load spectrum of a gearbox of a two-gear electric off-road vehicle. The method comprises the steps of establishing a durable simulation model of the two-gear electric off-road vehicle; sequentially carrying out dynamic simulation on the target vehicle under a plurality of durable working conditions, and recording real-time data of the target vehicle; acquiring a design check load spectrum of a target vehicle gearbox according to real-time data in the simulation process; the gearbox bench test load spectrum is established according to the design check load spectrum, and the requirements of durability check and test verification in the development stage of the two-gear electric off-road vehicle gearbox project can be met.

Description

Durable load spectrum generation method and system for gearbox of two-gear electric off-road vehicle

Technical Field

The invention relates to the technical field of gearbox bench tests, in particular to a method and a system for generating a durable load spectrum of a gearbox of a two-gear electric off-road vehicle.

Background

With the development of motorization in the automobile industry, more and more automobile models begin to switch the power assembly from traditional fuel drive to electric drive. Because the driving motor has the capacity of high rotating speed, most of the existing electric automobiles adopt a transmission form that a fixed speed ratio reduction box is matched with the driving motor, and for the application scene of the electric off-road vehicle, the electric off-road vehicle needs to run in the working conditions of muddy, desert and pit climbing, and more requirements are provided for the speed ratio design of a gearbox of the electric off-road vehicle. At present, the electric vehicle generally adopts a two-gear gearbox, and the dynamic property of the electric off-road vehicle at a low-speed section can be effectively improved due to the fact that the first-gear speed ratio is large, the improvement of the highest vehicle speed can be realized by means of the small second-gear speed ratio, and meanwhile the driving efficiency of the whole vehicle can be improved through the optimization of working points. In the early development stage of the gearbox, whether in part design check or bench test verification, a reasonably reliable load spectrum is required as an input.

A common gearbox design check applies a load spectrum to parts such as a shaft, a gear, a bearing, a differential and a shell by means of finite elements and an analytical method, and calculates the fatigue life and the safety factor of the parts. The electric drive gearbox bench test refers to a process of testing the endurance strength of the motor, subsystems and parts of the gearbox by using a test bench, and the daily running and road test working conditions of a full-life-cycle real vehicle are mainly simulated through the bench test. The electric drive power assembly system can be verified and evaluated in time in the engineering design and sample development stages, so that potential design problems can be identified and optimized in time. The effectiveness of the gearbox bench test and the accuracy of design check depend on the relevance of the load spectrum and the service condition of an end customer. How to generate a corresponding load spectrum according to different vehicle parameters, motor parameters, gearbox parameters, control strategies and service life requirements is a crucial link. At present, the generation of the load spectrum of the electric drive reduction gearbox is usually obtained by actual measurement, road load data under different working conditions are collected by a real vehicle, and frequency extrapolation and synthesis are carried out according to design requirements and distribution proportions of the working conditions, so that the durable load spectrum of the whole vehicle in the whole life cycle is compiled. The method has the advantages of full-range coverage of the load and the defects of no obvious unevenness of actual load distribution and no strong correlation with the use working condition of a client and the parameters of the whole vehicle, so that the difference between a load spectrum and the fatigue damage generated by actual driving of the client is large. In addition, the existing load spectrum generation method is mostly limited to a single-gear electrically-driven gearbox, most matched vehicles are passenger vehicles, and the load spectrum generation research on the electric off-road vehicle, particularly a two-gear electrically-driven gearbox, is not published yet.

Disclosure of Invention

The invention aims to provide a method and a system for generating a durable load spectrum of a two-gear electric off-road vehicle gearbox, which can meet the requirements of durable checking and test verification in the project development stage of the two-gear electric off-road vehicle gearbox.

In order to solve the technical problem, the invention provides a durable load spectrum generation method for a two-gear electric off-road vehicle gearbox, which comprises the following steps of:

the method comprises the following steps: establishing a durable simulation model of the two-gear electric off-road vehicle;

step two: sequentially carrying out dynamic simulation on the target vehicle under a plurality of durable working conditions, and recording real-time data of the target vehicle;

step three: acquiring a design check load spectrum of a target vehicle gearbox according to real-time data in the simulation process;

step four: and establishing a gearbox rack test load spectrum according to the design check load spectrum.

The improvement of the load spectrum generation method for the gearbox endurance bench test is characterized in that in the third step, the design check load spectrum comprises an axle tooth design check load spectrum, and the acquisition process comprises the following steps:

step a1: screening and classifying real-time data of all working condition simulation processes to obtain a relation matrix of motor torque-motor rotating speed-time-gear of each working condition, wherein the gear comprises a first gear and a second gear;

step a2: calculating the number of motor rotation turns corresponding to the torque of each time interval in a motor torque-motor rotation speed-time-gear matrix of each working condition to obtain a relationship matrix of the motor torque-motor rotation speed-time-motor rotation number-gear, wherein the time interval is a sampling period;

step a3: dividing a motor torque value into a plurality of torque sections in a first span in a motor torque-motor rotating speed-time-motor rotating number-gear matrix of each working condition;

step a4: accumulating and counting the number of motor rotation turns corresponding to each torque section under each working condition to obtain the total number of motor rotation turns corresponding to each torque section, namely obtaining the load spectrums corresponding to the motor torques and the number of motor rotation turns at different gears under each working condition;

step a5: multiplying the number of revolutions of the motor of a single working condition load spectrum by the number of cycles of the working condition to obtain an extrapolated working condition load spectrum;

step a6: and superposing the load spectrums after the outward pushing of all the working conditions to respectively obtain a relation matrix of the motor torque and the number of rotation turns of the motor under each gear, namely designing and checking the load spectrums by the shaft teeth under each gear.

Further, the fourth step includes establishing an axial tooth bench test load spectrum according to the axial tooth design check load spectrum, and the establishing method includes:

step b1: according to a Palmgren-Miner linear damage accumulation theory and an axle tooth design check load spectrum of each gear, calculating the total damage equivalent of each gear;

and b2: dividing the maximum torque of the motor to the maximum negative torque to obtain a torque section of a gearbox bench test;

step b3: acquiring the number of rotating circles of a motor corresponding to a torque section under each gear according to the total damage equivalent of the gear of the gearbox of each gear;

step b4: and multiplying the number of rotation turns of the motor corresponding to the torque section under each gear by a first acceleration coefficient to obtain a load spectrum of the torque of the gear of the gearbox at each gear and the number of rotation turns of the motor after acceleration, namely the load spectrum of the shaft tooth rack test of the gearbox.

As another improvement of the method for generating the load spectrum of the transmission endurance bench test of the present invention, in step three, the designing and checking the load spectrum further includes designing and checking the load spectrum of the shift system, and the obtaining process includes: .

Step d1: screening and classifying real-time data of all working condition simulation processes to obtain a relation matrix of motor torque-motor rotating speed-times-gear shifting types of all working conditions, wherein the gear shifting types comprise upshifting and downshifting;

step d2: in a relation matrix of motor torque-motor rotating speed-times-gear shifting types of all working conditions, motor torque and motor rotating speed are classified into a plurality of torque sections and rotating speed sections;

step d3: accumulating and counting the corresponding gear shifting times of each rotating speed section and each torque section under each working condition;

step d4: multiplying the number of gear shifting times corresponding to each rotating speed section and each torque section under each working condition by the number of working condition circulation times to obtain an extrapolated working condition motor torque-motor rotating speed-number-gear shifting type matrix;

step d5: and superposing the motor torque-motor rotating speed-frequency-gear shifting type matrixes after the external pushing of all the working conditions to respectively obtain the motor torque-motor rotating speed-frequency matrixes under each gear shifting type, namely designing and checking a load spectrum of the gear shifting system under each gear shifting type.

Further, the fourth step also comprises the step of establishing a bench test load spectrum of the gear shifting system according to the load spectrum designed and checked by the gear shifting system, and the establishing method comprises the following steps:

step e1: according to a Palmgren-Miner linear damage accumulation theory and a gear shifting system design checking load spectrum under each gear shifting type, calculating the total damage equivalent of each rotating speed section under each gear shifting type;

step e2: calculating the corresponding gear shifting times by the maximum motor torque operation of each rotating speed section under the condition that the total damage equivalent of each rotating speed section under each gear shifting type is the same;

step e3: and secondly multiplying the gear shifting times corresponding to the maximum motor torque operation of each rotating speed section by an acceleration coefficient to obtain a relation matrix of the maximum motor torque, the motor rotating speed, the times and the gear shifting type, namely the rack test load spectrum of the gear shifting system.

The invention discloses a two-gear electric off-road vehicle gearbox endurance load spectrum generation system based on the two-gear electric off-road vehicle gearbox endurance load spectrum generation method, which is characterized by comprising the following steps of:

the modeling module is used for establishing a durable simulation model of the two-gear electric off-road vehicle;

the simulation module is used for carrying out dynamic simulation on the target vehicle under a plurality of durable working conditions in sequence and recording real-time data of the target vehicle;

the acquisition module is used for acquiring a design check load spectrum of the target vehicle gearbox according to real-time data in the simulation process;

and the establishing module is used for establishing a gearbox rack test load spectrum according to the design check load spectrum.

The invention has the beneficial effects that: the load spectrum can be subjected to equivalent damage calculation and service life prediction of the gearbox, a complex modeling analysis link is avoided, the development efficiency is improved, and the requirements of durability check and test verification on the two-gear electric off-road vehicle gearbox project development stage are met.

Drawings

In the drawings:

FIG. 1 is a flow chart of a transmission endurance bench test load spectrum generation method of the present invention.

FIG. 2 is a structural block diagram of a durable simulation model of the two-gear electric off-road vehicle.

FIG. 3 is a block diagram of a gearbox endurance bench test load spectrum generation method according to the present invention.

FIG. 4 is a block diagram of a transmission endurance bench test load spectrum generation system of the present invention.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto.

Example 1

As shown in FIG. 1, the invention discloses a method for generating a durable load spectrum of a gearbox of a two-gear electric off-road vehicle, which comprises the following steps:

step S10: and establishing a durable simulation model of the two-gear electric off-road vehicle. The durable simulation model of the two-gear electric off-road vehicle comprises a working condition module, a terrain module, a driver module, a motor control module, a battery module, a gearbox control module, a whole vehicle and tire module and a data monitoring module.

As shown in fig. 2, the terrain module is in communication connection with the working condition module, the working condition module is in communication connection with the driver module, the driver module is in communication connection with the motor control module, the motor control module is in communication connection with the motor module, the motor module is in communication connection with the battery module, the motor module is in communication connection with the gearbox module, the gearbox module is in communication connection with the whole vehicle and the tire module, and the whole vehicle and the tire module are in communication connection with the data monitoring module.

The working condition module is used for defining a corresponding working condition list and specific working condition information in the whole life cycle of the electric off-road vehicle. The terrain module is used for defining corresponding road condition information in the whole life cycle of the electric off-road vehicle, and the road condition information comprises road mileage, road gradient, road curvature, road roughness and other information. The driver module is used for generating an accelerator pedal signal and a brake pedal signal according to the difference between the target vehicle speed and the actual vehicle speed. The motor control module is used for converting an accelerator pedal signal and a brake pedal signal of a driver into a required driving torque and an energy recovery torque of the motor. The motor module is used for converting the required torque and the required rotating speed signal input by the motor control module into the actual output torque and the actual working current of the motor. The battery module is used for calculating the power consumption of the motor and the electric accessories and the SOC (State of charge) State of the battery, and obtaining the endurance mileage of the electric off-road vehicle under the working condition.

The gearbox control module is used for judging and selecting an expected gear according to an accelerator pedal signal and an actual vehicle speed signal output by the driver module, and generating a gear shifting execution signal according to a required gear signal. The gearbox module is used for converting the torque and the rotating speed at the motor end into the torque and the rotating speed at the half shaft end and executing gear shifting action according to a required gear signal output by the gearbox control module. The whole vehicle and tire module is used for calculating the real-time vehicle speed, acceleration and driving mileage of the vehicle, calculating the driving resistance of the tire and the ground and realizing the interconversion of the half-axle end output signal and the wheel end signal. The data monitoring module is used for collecting signals and data generated by actual operation of each module and storing the signals and data in a working space so as to support subsequent load spectrum generation.

The dynamic simulation system is an electric cross-country vehicle endurance load spectrum generation system established in a Matlab/Simulink environment, is an open-source Simulink model, has editability and modification, and is suitable for vehicle model architectures of various driving modes. The parameter input of the electric off-road vehicle gearbox load spectrum generation system uses a script file with the extension name of m, the input parameter adopts actual parameters of the whole vehicle design, each signal in each module of the electric off-road vehicle performance simulation system can be observed in real time by using a Scope oscilloscope, the output result of the pure electric vehicle performance simulation system can be configured according to project requirements, the output form can be various forms such as Matlab signal output, figure output, txt text, word document and the like, the function of automatically generating the load spectrum effectively combines data processing and standardized report generation, and the electric off-road vehicle gearbox load spectrum generation system has good engineering actual guidance significance.

And then, reading and defining simulation parameters in the simulation model, wherein the simulation parameters are used for reading corresponding working condition files, whole vehicle files, motor files, gearbox gear shifting strategy files, energy recovery strategy files and battery files according to the vehicle type corresponding to the project development by using script files with the extension name of m.

The specific parameters defined by the working condition file are as follows: the expected speed and time curve, the gradient and mileage curve, and the turning radius and mileage curve corresponding to each working condition. The specific parameters defined by the whole vehicle file are as follows: full load mass, no load mass, wheel base, driving mode, front and rear axle load distribution, height of center of mass, tire radius, tire rolling friction coefficient, tire sliding friction coefficient, wind resistance coefficient, windward area and the like. Specific parameters defined by the gearbox file are: the gear ratio of each level of the first gear, the rotational inertia of each level of the first gear, the transmission efficiency of each level of the first gear, the gear ratio of each level of the second gear, the rotational inertia of each level of the second gear, the transmission efficiency of each level of the second gear and the parameters of the synchronizer.

Specific parameters defined by the motor file are as follows: the motor efficiency curve comprises a motor external characteristic curve, a motor peak torque, a motor rated torque, a motor maximum rotating speed, a motor efficiency curve and a motor rotor moment of inertia; and (3) a motor torque limiting strategy corresponding to each gear, wherein the driving mode is a two-drive mode rear drive. The specific parameters defined by the gearbox gear-shifting strategy file are as follows: the corresponding gear-up curves under different accelerator opening degrees and vehicle speeds, and the corresponding gear-down curves under different accelerator opening degrees and vehicle speeds. Specific parameters defined by the energy recovery policy file are as follows: the minimum vehicle speed for starting energy recovery, the distribution ratio of motor braking and mechanical braking in energy recovery under different braking strengths, and the maximum energy recovery torque limit of the motor. Specific parameters defined by the battery file are: battery capacity, battery electromotive force, and SOC characteristic curve. The input parameter files are Excel files, and reading, editing and storing of programs are facilitated. After the corresponding configuration file is read, defining each parameter into a working space, and endowing each parameter to a variable corresponding to the complete vehicle dynamics simulation model.

Step S20: and performing dynamic simulation on the target vehicle under a plurality of durable working conditions in sequence, and recording real-time data of the target vehicle.

The dynamic simulation under the durable working condition is used for calculating the original durable data of the whole electric off-road vehicle and providing a basic data source for the load spectrum generation of the gearbox. And the dynamic simulation carries out durable simulation and calculation on the whole electric off-road vehicle system and the gearbox system according to the whole vehicle dynamic formula and the information transmission between the modules.

The specific steps are as shown in fig. 3, the simulation system reads the corresponding working condition information in sequence according to the working condition list, and the working condition types are divided into two categories: normal and off-road conditions. Wherein the conventional operating conditions include: urban working conditions, high-speed working conditions, suburban working conditions and mountain working conditions; the off-road conditions include: pit climbing working conditions and desert working conditions. And when the simulation mileage of each working condition reaches the target mileage of the working condition, the simulation of the single working condition is terminated, and the simulation system enters the simulation process of the next working condition. After the simulation of a single working condition is ended, the system automatically stores real-time data of the electric off-road vehicle under the working condition, wherein the real-time data comprises vehicle speed, vehicle acceleration, accelerator pedal depth, brake pedal depth, motor torque, motor rotating speed, driving mileage, gear information and the like. After the working condition simulation in all the lists is finished, the endurance simulation of the whole system on the electric off-road vehicle is finished, and all the data information is stored in a working space for subsequent calling. The method has the advantages of complete working condition types, high running speed, strong correlation with finished vehicle parameters and motor parameters, customized torque distribution and energy recovery strategies and the like.

Step S30: and acquiring a design check load spectrum of the target vehicle gearbox according to real-time data in the simulation process. The design check load spectrum is divided into two parts: the shaft tooth design checking load spectrum is used for checking the durability and reliability of the shaft tooth, the bearing and the differential; the gear shifting system is designed to check a load spectrum and is used for checking the durability and reliability of the synchronizer and the gear shifting hub.

(1) The steps of the process for acquiring the load spectrum for checking the design of the shaft teeth are as follows:

step a1: and screening and classifying real-time data of all working condition simulation processes to obtain a relation matrix of motor torque-motor rotating speed-time-gear of each working condition, wherein the gear comprises a first gear and a second gear. Firstly, motor rotating speed-motor torque-time-gear data files generated by simulating all working conditions are sequentially screened and classified according to gear types, and two types of data of motor rotating speed-motor torque-time-first gear and motor rotating speed-motor torque-time-second gear are respectively obtained.

Step a1.5: and performing low-pass filtering processing on a rotating speed-torque-time-gear matrix of the input shaft of the gearbox, eliminating abnormal points in the data, and performing resampling and interpolation processing to ensure that time intervals corresponding to all motor torque data are the same value.

Step a2: in the motor torque-motor rotating speed-time-gear matrix of each working condition, calculating the number of motor rotating turns corresponding to the torque of each time interval to obtain a relation matrix of the motor torque-motor rotating speed-time-motor rotating number-gear, wherein the time interval is a sampling period. Optionally, the number of revolutions of the motor in a single time interval is equal to the average rotational speed of the motor in that interval multiplied by the time interval.

Step a3: in a motor torque-motor rotating speed-time-motor rotating number-gear matrix of each working condition, a motor torque value is divided into a plurality of torque sections in a first span. Optionally, the first span is 10nxm, i.e., the rounding process is performed every 10nxm, and the upper limit of each torque segment is the torque value of the torque segment, so as to perform strengthening.

Step a4: and accumulating and counting the number of rotation turns of the motor corresponding to each torque section under each working condition to obtain the total number of rotation turns of the motor corresponding to each torque section, namely obtaining the load spectrums corresponding to the motor torques and the number of rotation turns of the motor at different gears under each working condition. Alternatively, the counting may be performed using a magnitude counting algorithm.

Step a5: and multiplying the number of revolutions of the motor of the single working condition load spectrum by the number of cycles of the working condition to obtain the extrapolated working condition load spectrum.

Step a6: and superposing the load spectrums after the outward pushing of all the working conditions to respectively obtain a relation matrix of the motor torque and the number of rotation turns of the motor under each gear, namely designing and checking the load spectrums by the shaft teeth under each gear. The gears comprise a first gear and a second gear, and the load spectrum generation result of the design and check of the shaft teeth of the gearbox is shown in the table 1.

Table 1: axle tooth design checking load spectrum under first gear and second gear

(2) The process for acquiring the design check load spectrum of the gear shifting system comprises the following steps:

step d1: screening and classifying real-time data of all working condition simulation processes to obtain a relation matrix of motor torque-motor rotating speed-times-gear shifting types of all working conditions, wherein the gear shifting types comprise gear upshifting and gear downshifting.

Step d2: in a relation matrix of motor torque-motor rotating speed-times-gear shifting types of all working conditions, the motor torque and the motor rotating speed are classified into a plurality of torque sections and rotating speed sections.

Step d3: and accumulating and counting the corresponding gear shifting times of each rotating speed section and each torque section under each working condition. Optionally, the torque is segmented by a span of 50n × m, and the upper limit value of each torque segment is taken as the torque value of the segment, and the rotation speed is segmented by a span of 1000RPM, and the upper limit value of each rotation speed segment is taken as the rotation speed value of the segment.

Step d4: multiplying the number of gear shifting times corresponding to each rotating speed section and each torque section under each working condition by the number of working condition circulation times to obtain an extrapolated working condition motor torque-motor rotating speed-number-gear shifting type matrix.

Step d5: and superposing the motor torque-motor speed-frequency-gear shifting type matrixes after the external pushing of all the working conditions to respectively obtain the motor torque-motor speed-frequency matrixes under each gear shifting type, namely designing and checking a load spectrum of the gear shifting system under each gear shifting type, as shown in tables 2 and 3.

Rotational speed/torque	350	300	250	200	150	100	50
								5000	264	528	792	1056	1320	1584	1848
6000	451	429	429	429	429	429	429
								7000	638	517	517	517	517	517	517
8000	825	737	737	737	737	737	737
								9000		858	858	858	858	858	858
10000			1078	1078	1078	1078	1078

TABLE 2 Motor Torque (N m) -Motor speed (RPM) -times matrix for upshifts

TABLE 2 Motor Torque (N × m) -Motor speed (RPM) -times matrix for downshift

Step S40: and establishing a gearbox rack test load spectrum according to the design check load spectrum. Correspondingly:

(1) And checking the load spectrum according to the design of the shaft tooth to establish a test load spectrum of the shaft tooth rack.

The actual bench test load spectrum needs to complete the equivalent damage examination of the whole life cycle of the gearbox in as short a time as possible, so the design check load spectrum generated in the step S30 needs to be accelerated and strengthened. After the design and check load spectrum is generated, the total damage equivalent of the first gear and the second gear of the load spectrum can be respectively calculated according to a Palmgren-Miner linear accumulated damage rule. According to different S-N curve slope factors corresponding to different parts of the gearbox, fatigue damage equivalent weight generated by different parts (shaft teeth, bearings and differentials) in the gearbox can be calculated and analyzed. And converting the loads of a large number of low-torque sections of the design check load spectrum to middle-high torque sections, and collecting the turns of the final typical torque section to obtain the distribution of the torque sections and the turns of the rotation of the load spectrum of the bench test. The specific establishment method comprises the following steps:

step b1: and (4) according to a Palmgren-Miner linear damage accumulation theory and the design of the shaft teeth of each gear, checking a load spectrum, and calculating the total damage equivalent of each gear. First, the damage equivalent, the tooth flank damage DV3, the bearing damage, and the tooth root damage DV6 corresponding to each torque segment in the design load spectrum are calculated, for example: separately calculated for the 350Nm torque segment:

first gear DV3=350^3 × 983139; DV6=350^6 × 983139;

DV3=350^3 × 491569; DV6=350^6 × 491569;

...

the damage values for each torque segment were calculated sequentially and the results are given in table 4 below:

TABLE 4 damage equivalents to Torque segments

The calculated equivalents for each torque band are then summed to obtain the total equivalents for first gear and second gear for total tooth flank damage and tooth root damage, respectively, as shown in Table 5 below.

General tooth surface damage (first gear)	Total root damage (first gear)	Total tooth surface damage (second gear)	Total root damage (first gear)
				6.72941E+14	6.52826E+21	3.36471E+14	5.62462E+21

TABLE 5 total damage equivalent of first and second gear teeth

Step b2: and dividing the maximum torque of the motor to the maximum negative torque to obtain a torque section of the gearbox bench test. The appropriate span is usually selected empirically, and can also be divided according to the distribution of the number of revolutions of the motor in each torque segment in the standard 1. Setting the number of rotation turns of the motor corresponding to each torque section of the first gear as an unknown number: x1, X2,. Xn; setting the number of rotation turns of the motor corresponding to each torque section of the second gear as an unknown number: y1, Y2,. Yn, to obtain a bench test load spectrum (correspondence of motor torque and number of revolutions of the motor) as in table 6 below.

Torque of	Number of turns (first gear)	Number of turns (second gear)
			350	X1	Y1
300	X2	Y2
			250	X3	Y3
200	X4	Y4
			-50	X5	Y5
-100	X6	Y6
			-150	X7	Y7
-200	X8	Y8

TABLE 6 bench test load spectrum of axial teeth

And b3: and acquiring the number of rotating circles of the motor corresponding to the torque section under each gear according to the total damage equivalent of the gear of the gearbox of each gear. At first gear, since the equation for the total equivalent of tooth flank damage and tooth root damage cannot be satisfied simultaneously, one equation can be exchanged for an inequality, which can be listed as follows:

350^ 3X 1+300^ 3X 2+. 9. + (| -200 |). 3X 8= total tooth flank damage equivalent;

350^ 6X 1+300^ 6X 2+. 9. + (| -200 |). 6X 8 is more than or equal to the total equivalent of tooth root damage;

optionally, since the above calculation formula cannot calculate a specific value, although the calculation formula can be designed empirically, an objective algorithm needs to continue to add other conditions for calculation and solution.

Conditions may be added: the motor rotation ring ratio of each torque section can directly calculate an accurate numerical value. Specifically, the method comprises the following steps: obtaining the proportional relation of each torque section divided by a second span corresponding to the total number of rotating turns of the motor according to the relation matrix of the torque of the motor, the rotating speed of the motor, the time, the number of rotating turns of the motor and the gear; and calculating the number of the motor rotation turns corresponding to the torque section divided by the second span under each gear according to the same total damage equivalent of the gear of the gearbox of each gear.

Conditions may also be added: the total number of the rotating turns of the motors in the positive and negative torque sections is the same.

Step b4: and multiplying the number of rotation turns of the motor corresponding to the torque section under each gear by a first acceleration coefficient to obtain a torque of the gear of the gearbox of each gear and a load spectrum of the number of rotation turns of the motor after acceleration, namely the load spectrum of the gearbox shaft tooth rack test. Optionally, the first acceleration coefficient is 0.1, so that the actual cycle time is reduced, and the bench test is completed quickly.

Step b5: and optimizing the load spectrum of the shaft tooth bench test. The obtained shaft tooth bench test load spectrum is a total load condition, and when the bench test is specifically carried out, in order to more fully reflect the motion condition of the gearbox, the loading time of each torque section during the test needs to be sliced and divided, and the successively loading sequence of each divided section is arranged to form a plurality of cycles, so that the motion condition of the gearbox is more approximate. The optimization method comprises the following steps:

step c1: and acquiring the rotating speed corresponding to each torque section under each gear in the shaft tooth rack test load spectrum according to the external characteristic curve of the motor. And obtaining the motor rotating speed under the working condition corresponding to the torque section according to the external characteristic curve of the motor, and calculating and evaluating the working power of the motor of each test section to ensure that the working power of the durability test of the gearbox is between the rated power and the peak power.

Optionally, the upper limit of each torque segment is used as the torque value of the torque segment, and different gear shifting curves are respectively adopted in the normal working condition and the off-road working condition.

Step c2: and obtaining the running time of the torque section according to the rotation number and the rotation speed of each torque section under each gear in the shaft tooth rack test load spectrum. And multiplying the number of revolutions of the motor by the rotating speed to obtain the running time.

And c3: setting cycle times of bench tests, and slicing the operation duration of each torque section according to the cycle times to obtain operation duration segments of a single torque section in each bench test cycle under each gear;

and c4: and sequencing the torque sections in each gear in a loading process in a cycle, and correspondingly matching the corresponding motor torque, the motor rotating speed, the running time section and the cycle times to obtain a final gearbox shaft tooth bench test load spectrum. Grouping and numbering different torque sections of different gears, matching corresponding data to the torque sections to obtain a final bench test load spectrum as shown in tables 7 and 8, wherein the negative value of the power is the direction of the corresponding torque.

Let the values of X1, X2,. X8, which are recommended according to the above, correspond to: 1024476, 2247093, 4864824, 5769258, 22839629, 3843837, 1288467, 842135; the values of Y1, Y2,. Y8 correspond to: 1473495, 10270819, 15897764, 16007912, 13556090, 11660764, 5086191, 2086191.

TABLE 7 bench test load Spectrum for first gear

TABLE 8 bench test load Spectrum for first gear

The specific test load spectra were run in the following order:

the test sequence of the first gear is A1> B1> A2> B2> A3> B3> A4> B4; after one large cycle is finished, a short-time working condition of small torque, low rotating speed and low differential speed is carried out to cool the gearbox system; and (5) carrying out a next large-cycle working condition test after the short-time working condition is ended, and circulating for 100 times.

The test sequence of second gear is C1> D1> C2> D2> C3> D3> C4> D4; after one large cycle is finished, a short-time working condition of small torque, low rotating speed and low differential speed is carried out to cool the gearbox system; and after the short-time working condition is finished, carrying out a next large-cycle working condition test for 100 cycles.

(2) Checking a load spectrum according to the design of the gear shifting system to establish a rack test load spectrum of the gear shifting system, wherein the establishing method comprises the following steps:

step e1: according to the Palmgren-Miner linear damage accumulation theory and the design and check load spectrum of the gear shifting system under each gear shifting type, calculating the total damage equivalent of each rotating speed section under each gear shifting type, for example: the original design spectrum of the gear-up process has a plurality of torque sections corresponding to 5000RPM, and the gear-shifting damage equivalent is 350^2 ^ 264+300^2 ^ 528+. + -.. 50^2.

Step e2: and calculating the corresponding gear shifting times by using the maximum motor torque of each rotating speed section to operate under the condition that the total damage equivalent of each rotating speed section under each gear shifting type is the same. For example, the total shift damage of the 5000RPM rotation speed section divided by (350 ^ 3) is 7392, and the 7392 is that the number of times of torque action in the rotation speed section is converted into the number of times of shifting at the maximum torque, and the number of tests is reduced.

Step e3: and secondly multiplying the gear shifting times corresponding to the maximum motor torque operation of each rotating speed section by an acceleration coefficient to obtain a relation matrix of the maximum motor torque, the motor rotating speed, the times and the gear shifting type, namely the rack test load spectrum of the gear shifting system. The optional second acceleration factor is taken to be 1, no acceleration is performed, and the resulting bench test load spectrum of the gear shift system is as follows in tables 9 and 10.

Rotational speed (rpm)	Torque (N x m)	Number of times
			5000	350	7392
6000	350	3025
			7000	350	3740
8000	350	5247
			9000	300	6160
10000	250	7667

TABLE 9 bench test load Spectrum for upshifting

Rotational speed (rpm)	Torque (N x m)	Number of times
			5000	350	8470
6000	350	4103
			7000	350	4818
8000	350	6325
			9000	300	7238
10000	250	8745

TABLE 10 bench test load spectra for upshifts

As shown in FIG. 4, the system based on the method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle has the advantages of the method and the implementation process, and comprises the following steps:

the modeling module is used for establishing a durable simulation model of the two-gear electric off-road vehicle;

the simulation module is used for carrying out dynamic simulation on the target vehicle under a plurality of durable working conditions in sequence and recording real-time data of the target vehicle;

the acquisition module is used for acquiring a design check load spectrum of the target vehicle gearbox according to real-time data in the simulation process;

and the establishing module is used for establishing a gearbox rack test load spectrum according to the design check load spectrum.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the scope of protection thereof, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: after reading this disclosure, those skilled in the art will be able to make various changes, modifications and equivalents to the embodiments of the invention, which fall within the scope of the appended claims.

Claims (10)

1. A method for generating a durable load spectrum of a gearbox of a two-gear electric off-road vehicle is characterized by comprising the following steps:

the method comprises the following steps: establishing a durable simulation model of the two-gear electric off-road vehicle;

step two: sequentially carrying out dynamic simulation on the target vehicle under a plurality of durable working conditions, and recording real-time data of the target vehicle;

step three: acquiring a design check load spectrum of a target vehicle gearbox according to real-time data in the simulation process;

step four: and establishing a gearbox rack test load spectrum according to the design check load spectrum.

2. The method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle according to claim 1, wherein in the third step, the design and check load spectrum comprises an axle gear design and check load spectrum, and the obtaining process comprises:

step a1: screening and classifying real-time data of all working condition simulation processes to obtain a relation matrix of motor torque-motor rotating speed-time-gear of each working condition, wherein the gear comprises a first gear and a second gear;

step a2: calculating the number of motor rotation turns corresponding to the torque of each time interval in a motor torque-motor rotation speed-time-gear matrix of each working condition to obtain a relationship matrix of the motor torque-motor rotation speed-time-motor rotation number-gear, wherein the time interval is a sampling period;

step a3: dividing a motor torque value into a plurality of torque sections in a first span in a motor torque-motor rotating speed-time-motor rotating number-gear matrix of each working condition;

step a4: accumulating and counting the number of motor rotation turns corresponding to each torque section under each working condition to obtain the total number of motor rotation turns corresponding to each torque section, namely obtaining the load spectrums corresponding to the motor torques and the number of motor rotation turns at different gears under each working condition;

step a5: multiplying the number of revolutions of the motor of a single working condition load spectrum by the number of cycles of the working condition to obtain an extrapolated working condition load spectrum;

step a6: and superposing the load spectrums after the outward pushing of all the working conditions to respectively obtain a relation matrix of the motor torque and the number of rotation turns of the motor under each gear, namely designing and checking the load spectrums by the shaft teeth under each gear.

3. The method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle according to claim 2, wherein: before the step a2, further comprising,

and carrying out low-pass filtering processing on the rotation speed-torque-time-gear matrix of the input shaft of the gearbox, eliminating abnormal points in the data, and carrying out resampling and interpolation processing to ensure that time intervals corresponding to all motor torque data are the same value.

4. The method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle as recited in claim 2, wherein the fourth step comprises establishing an axle tooth bench test load spectrum according to the axle tooth design check load spectrum, and the establishing method comprises the following steps:

step b1: according to a Palmgren-Miner linear damage accumulation theory and the design and check load spectrum of the shaft teeth of each gear, calculating the total damage equivalent of each gear;

and b2: dividing the maximum torque of the motor to the maximum negative torque to obtain a torque section of a gearbox bench test;

step b3: acquiring the number of rotating circles of a motor corresponding to a torque section under each gear according to the total damage equivalent of the gear of the gearbox of each gear;

step b4: and multiplying the number of rotation turns of the motor corresponding to the torque section under each gear by a first acceleration coefficient to obtain a torque of the gear of the gearbox of each gear and a load spectrum of the number of rotation turns of the motor after acceleration, namely the load spectrum of the gearbox shaft tooth rack test.

5. The method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle according to claim 4, wherein the step b3 comprises the following steps:

obtaining the proportional relation of each torque section divided by a second span corresponding to the total number of rotating turns of the motor according to the relation matrix of the torque of the motor, the rotating speed of the motor, the time, the number of rotating turns of the motor and the gear;

and calculating the number of the motor rotation turns corresponding to the torque section divided by the second span under each gear according to the same total damage equivalent of the gear of the gearbox of each gear.

6. The method for generating the durable load spectrum of the two-gear electric off-road vehicle gearbox according to claim 4, further comprising the step of, after step b4: step b5: optimizing the load spectrum of the shaft tooth bench test, wherein the optimizing method comprises the following steps:

step c1: acquiring the rotating speed corresponding to each torque section under each gear in the shaft tooth rack test load spectrum according to the external characteristic curve of the motor;

step c2: obtaining the running time of each torque section according to the number of rotation turns and the rotating speed of each torque section under each gear in the shaft tooth rack test load spectrum;

and c3: setting cycle times of bench tests, and slicing the operation duration of each torque section according to the cycle times to obtain operation duration segments of a single torque section in each bench test cycle under each gear;

and c4: and sequencing the torque sections in each gear in a loading process in a cycle, and correspondingly matching the corresponding motor torque, the motor rotating speed, the running time section and the cycle times to obtain a final gearbox shaft tooth bench test load spectrum.

7. The method for generating the durable load spectrum of the transmission of the two-gear off-road electric vehicle according to claim 1, wherein in step three, the designing and checking load spectrum further comprises a shifting system designing and checking load spectrum, and the obtaining process comprises: .

Step d1: screening and classifying real-time data of all working condition simulation processes to obtain a relation matrix of motor torque-motor rotating speed-times-gear shifting types of all working conditions, wherein the gear shifting types comprise gear upshifting and gear downshifting;

step d2: in a relation matrix of motor torque-motor rotating speed-times-gear shifting types of all working conditions, motor torque and motor rotating speed are classified into a plurality of torque sections and rotating speed sections;

step d3: accumulating and counting the corresponding gear shifting times of each rotating speed section and each torque section under each working condition;

step d4: multiplying the number of gear shifting times corresponding to each rotating speed section and each torque section under each working condition by the number of working condition circulation times to obtain an extrapolated working condition motor torque-motor rotating speed-number-gear shifting type matrix;

and d5: and superposing the motor torque-motor rotating speed-frequency-gear shifting type matrixes after the extrapolation of all the working conditions to respectively obtain the motor torque-motor rotating speed-frequency matrixes under each gear shifting type, namely designing and checking a load spectrum of a gear shifting system under each gear shifting type.

8. The method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle as recited in claim 7, wherein the fourth step further comprises establishing a bench test load spectrum of the gear shifting system according to the design check load spectrum of the gear shifting system, and the establishing method comprises the following steps:

step e1: according to a Palmgren-Miner linear damage accumulation theory and a gear shifting system design checking load spectrum under each gear shifting type, calculating the total damage equivalent of each rotating speed section under each gear shifting type;

step e2: calculating the number of gear shifting times corresponding to the maximum motor torque operation of each rotating speed section under the condition that the total damage equivalent of each rotating speed section under each gear shifting type is the same;

step e3: and secondly multiplying the gear shifting times corresponding to the maximum motor torque operation of each rotating speed section by an acceleration coefficient to obtain a relation matrix of the maximum motor torque, the motor rotating speed, the times and the gear shifting type, namely the rack test load spectrum of the gear shifting system.

9. The method for generating the durable load spectrum of the gearbox of the two-gear electric off-road vehicle according to claim 1,

in the first step, the endurance simulation model of the two-gear electric off-road vehicle comprises the following steps: the system comprises a working condition module, a terrain module, a driver module, a motor control module, a battery module, a gearbox control module, a whole vehicle and tire module and a data monitoring module.

10. A two-gear off-road electric vehicle gearbox endurance load spectrum generation system based on the two-gear off-road electric vehicle gearbox endurance load spectrum generation method of any one of claims 1-9, comprising:

the modeling module is used for establishing a durable simulation model of the two-gear electric off-road vehicle;

the simulation module is used for carrying out dynamic simulation on the target vehicle under a plurality of durable working conditions in sequence and recording real-time data of the target vehicle;

the acquisition module is used for acquiring a design check load spectrum of the target vehicle gearbox according to real-time data in the simulation process;

and the establishing module is used for establishing a gearbox rack test load spectrum according to the design check load spectrum.

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