A bench fatigue test method based on transmission impact load spectrum

Abstract

A bench fatigue test method based on the transmission impact load spectrum obtains a fatigue bench spectrum with impact loads that is closer to actual working conditions, thereby guiding the design and development of new energy commercial vehicles and greatly improving the reliability of new energy commercial vehicles. At the same time, it can also significantly shorten the development cycle of new energy commercial vehicles and reduce development costs, which plays an important role in quickly bringing new energy commercial vehicles to market and seizing market opportunities.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy commercial vehicles, and in particular relates to a bench fatigue testing method based on a transmission impact load spectrum. Background Art

[0002] Since the industrialization of electric vehicles in the world in 2010, it has maintained rapid growth. The electrification of the automotive industry has also promoted the green transformation of commercial vehicles. In 2023, the proportion of new energy commercial vehicles reached 11.3%, and it is expected to exceed 15% in 2025. The main uses of new energy commercial vehicles are urban sanitation, logistics and transportation, urban muck trucks and engineering dump trucks. With the increase in the market ownership, the after-sales failures of new energy commercial vehicles have gradually increased. As a key component of commercial vehicles, the proportion of after-sales failures of transmissions directly affects the quality of the entire vehicle.

[0003] In the research and development of power transmission systems, bench testing is an important means to assess the reliability and durability of transmissions. At present, the fatigue test methods for the transmission systems of new energy commercial vehicles are based on the test methods of mechanical transmissions of commercial vehicles. There are inconsistencies between the bench test results and the after-sales fault manifestations, which makes the developed new energy products often unable to meet the actual use requirements well, and there is a large gap between the actual life and the design goals. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a bench fatigue testing method based on the transmission impact load spectrum, which solves the problem of inconsistent loads during fatigue bench testing of electric drive systems of new energy commercial vehicles and actual driving, and improves the reliability of new energy commercial vehicles subsequently redesigned and produced.

[0005] To achieve the above object, the technical solution adopted by the present invention includes:

[0006] A bench fatigue test method based on a transmission impact load spectrum comprises the following steps:

[0007] S1, collecting a load spectrum data set of a new energy commercial vehicle; the load spectrum data set includes a plurality of load spectrum data, each load spectrum data includes at least a motor output speed, a motor output torque, a gear position and a vehicle speed;

[0008] S2, preprocessing the load spectrum data set obtained in S1 to obtain a same-frequency load spectrum data set, where the same-frequency load spectrum data set includes a plurality of same-frequency load spectrum data;

[0009] S3, based on the equal damage theory, accelerate the same-frequency load spectrum data set obtained in S2 to the target torque and target speed to obtain the bench spectrum set of each gear, and then convert the bench spectrum set of each gear to the target life mileage to obtain the bench spectrum set of each gear with the target mileage; the bench spectrum set of each gear includes multiple bench spectra of each gear, and the bench spectrum set of each gear with the target mileage includes multiple bench spectra of each gear with the target mileage;

[0010] S4, counting the data whose absolute value of the difference between adjacent positive and negative motor output torques in each same-frequency load spectrum data set obtained in S2 is greater than a threshold value, to obtain the impact load spectrum set of each gear, and then converting the impact load spectrum set of each gear to the target life mileage to obtain the impact load spectrum set of each gear of the target mileage; the impact load spectrum set of each gear includes multiple impact load spectra of each gear, and the impact load spectrum set of each gear of the target mileage includes multiple impact load spectra of each gear of the target mileage;

[0011] S5, combining the bench spectrum set of each gear position of the target mileage obtained in S3 and the impact load spectrum of each gear position of the target mileage obtained in S4 to obtain a fatigue bench spectrum set with impact load, wherein the fatigue bench spectrum set with impact load includes multiple fatigue bench spectra with impact load.

[0012] Preferably, the preprocessing in S2 specifically includes converting each load spectrum data into a standard format, and converting each load spectrum data into a uniform collection frequency.

[0013] Preferably, the standard format in S2 is ".xlsx" format, ".txt" format or ".dat" format, and the unified acquisition frequency is 1 Hz, 10 Hz or 100 Hz.

[0014] Preferably, converting the bench spectrum set to the target life mileage in S3 is specifically to multiply the acceleration time and coefficient k in each bench spectrum, where coefficient k=L0 / L; wherein L represents the collection mileage, and the collection mileage is obtained by multiplying the vehicle speed collected in S1 by the unit time and then adding them together, and L0 represents the target mileage.

[0015] Preferably, converting the impact load spectrum set to the target life mileage in S4 is specifically to multiply the number of impact loads in each impact load spectrum by a coefficient k, where the coefficient k=L0 / L; wherein L represents the collection mileage, and L0 represents the target mileage.

[0016] Preferably, the threshold in S4 is the rated torque output by the motor.

[0017] Preferably, the torque change rate when the motor output torque passes through 0 in the impact load spectrum of each gear in S4 is reduced.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The bench fatigue testing method based on the transmission impact load spectrum of the present invention obtains a fatigue bench spectrum with impact load that is closer to the actual working condition, guides the design and development of new energy commercial vehicles, and greatly improves the reliability of new energy commercial vehicles; at the same time, it can also significantly shorten the development cycle of new energy commercial vehicles, reduce development costs, and play an important role in quickly launching new energy commercial vehicles to the market and seizing market opportunities. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 are all the same-frequency load spectrum data under the first gear in the embodiment;

[0022] Figure 2 is the data of the rack spectrum of each gear of the target mileage in the embodiment;

[0023] Figure 3 is the number of impacts of each gear in the embodiment;

[0024] Figure 4 is the change in motor output torque for one impact in this embodiment;

[0025] Figure 5 This is one cycle of the fatigue bench spectrum with impact load in the first gear in this embodiment. DETAILED DESCRIPTION

[0026] The invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention. All components and devices in the present invention, unless otherwise specified, are all components and devices known in the prior art.

[0027] Example

[0028] This embodiment discloses a bench fatigue test method based on a transmission impact load spectrum. This embodiment takes a fatigue bench spectrum of a four-speed new energy commercial vehicle transmission product as an example for explanation. The target working condition is heavy-load downhill and no-load uphill in a mining area, and includes the following steps:

[0029] S1, collecting a load spectrum data set of a new energy commercial vehicle on site; the load spectrum data set includes a plurality of load spectrum data, each load spectrum data includes at least time, motor output speed, motor output torque, gear position and vehicle speed;

[0030] The main driving condition of a four-speed new energy commercial vehicle in this embodiment is a mining area. A similar mining area is found in Henan. There are four-speed new energy commercial vehicles in this mining area, and load spectrum data is collected for them. The collected load spectrum data is in the ".MDF" format.

[0031] S2, preprocessing the load spectrum data set obtained in S1 to obtain a same-frequency load spectrum data set, wherein the same-frequency load spectrum data set includes a plurality of same-frequency load spectrum data;

[0032] Use CANape software to uniformly filter out the collected date, time, motor output speed, motor output torque, gear position and vehicle speed, convert all load spectrum data in ".MDF" format into ".xlsx" format; and integrate the frequency of all load spectrum data into 1Hz. Figure 1 These are all the load spectrum data with the same frequency in the 1st gear case.

[0033] S3, based on the equal damage theory, the same-frequency load spectrum data set obtained in S2 is accelerated to a target torque of 2400 Nm and a target speed of 1800 rpm to obtain a bench spectrum set of each gear, wherein the bench spectrum set of each gear includes a plurality of bench spectra of each gear;

[0034] Then, the bench spectrum set of each gear is converted to the target life mileage to obtain the bench spectrum set of each gear at the target mileage, wherein the bench spectrum set of each gear at the target mileage includes the bench spectrum of each gear at multiple target mileages; wherein, Figure 2 This is the data of the test bench spectrum from 1st to 4th gear based on 200,000 kilometers.

[0035] The bench spectrum set is converted to the target life mileage by multiplying the time in each bench spectrum by a coefficient k, where the coefficient k=L0 / L; wherein L represents the collection mileage, and the collection mileage is obtained by multiplying the vehicle speed collected by S1 by the unit time, and L0 represents the target mileage.

[0036] Among them, the equivalent damage theory can be found in GB3480.6; the target mileage L0 of this embodiment is 200,000 kilometers, and the collection mileage L is 198 kilometers, that is, the coefficient k=1010.

[0037] S4, counting data in which the absolute value of the difference between adjacent positive and negative motor output torques in each same-frequency load spectrum data set obtained in S2 is greater than a threshold, and obtaining an impact load spectrum set for each gear, wherein the impact load spectrum set for each gear includes a plurality of impact load spectra for each gear;

[0038] The threshold value can be set according to actual needs. The threshold value of this embodiment can be selected as the rated torque of the motor output, which is 1000Nm. In the actual operation, according to the peak output torque of the motor and the actual operating conditions of the vehicle, this embodiment selects -2000Nm to 1000Nm per second as the upper and lower limits of the change of the motor output torque. The mileage is 198 kilometers. The 1st gear, 2nd gear, 3rd gear and 4th gear generate 2, 3, 2 and 1 impacts respectively. The cycle time of 1 impact is 5s. Figure 4 As shown;

[0039] Then, the impact load spectrum set of each gear is converted to the target life mileage to obtain the impact load spectrum set of each gear at the target mileage, wherein the impact load spectrum set of each gear at the target mileage includes multiple impact load spectra of each gear at the target mileage; wherein, Figure 3 The number of impacts from 1st gear to 4th gear and the corresponding speed are shown based on 200,000 kilometers as an example.

[0040] In this embodiment, the impact load spectrum set is converted to the target life mileage by multiplying the number of impact loads in each impact load spectrum by a coefficient k, where the coefficient k=1010;

[0041] The acquisition frequency of this embodiment is relatively high. According to actual needs, the torque change rate when the motor output torque passes through 0 can be reduced, that is, Figure 4 The torque slope of the impact load spectrum shown when the motor output torque passes through 0 varies in multiple stages.

[0042] S5, combining the bench spectrum set of each gear of the target mileage obtained in S3 and the impact load spectrum of each gear of the target mileage obtained in S4, that is, averaging the impact times of each gear into the bench spectrum time of each gear, to obtain a fatigue bench spectrum set with impact load;

[0043] In the 1st to 4th gears disclosed in this embodiment, an impact will occur at an average of 76s, 47s, 48s, and 38s. Figure 5 What is shown is the change of the motor output torque in one cycle in the first gear, that is, the fatigue bench spectrum with impact load in the first gear. In this embodiment, 2020 cycles are required to complete the bench test in the first gear. When the torque drops from 2400Nm to -2000Nm, in order to reduce the load of the test bench, the torque change rate is reduced and the time is extended to 9s. The same applies to the other gears.

[0044] In the process of the transmission bench fatigue test of new energy commercial vehicles, this embodiment obtains a fatigue bench spectrum with impact loads that is closer to the actual working conditions, thereby guiding the design and development of new new energy commercial vehicles and greatly improving the reliability of new new energy commercial vehicles. At the same time, it can also significantly shorten the development cycle of new new energy commercial vehicles, reduce development costs, and play an important role in quickly launching new new energy commercial vehicles to the market and seizing market opportunities.

[0045] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0046] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0047] In addition, the various different implementation modes disclosed in this solution may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the content invented by the present disclosure.

Claims

1. A bench fatigue test method based on transmission impact load spectrum, characterized in that: The steps include: S1, collects the load spectrum data set of new energy commercial vehicles; The load spectrum data set includes a plurality of load spectrum data, each load spectrum data at least includes a motor output speed, a motor output torque, a gear position and a vehicle speed; S2, preprocessing the load spectrum data set obtained in S1 to obtain a same-frequency load spectrum data set, wherein the same-frequency load spectrum data set includes a plurality of same-frequency load spectrum data; S3, based on the equal damage theory, accelerate the same-frequency load spectrum data set obtained in S2 to the target torque and target speed to obtain the bench spectrum set of each gear, and then convert the bench spectrum set of each gear to the target life mileage to obtain the bench spectrum set of each gear at the target mileage; The bench spectrum set for each gear includes a plurality of bench spectra for each gear, and the bench spectrum set for each gear of the target mileage includes a plurality of bench spectra for each gear of the target mileage; S4, counting the data whose absolute value of the difference between adjacent positive and negative motor output torques in each same-frequency load spectrum data set obtained in S2 is greater than a threshold value, to obtain an impact load spectrum set of each gear, and then converting the impact load spectrum set of each gear to a target life mileage, to obtain an impact load spectrum set of each gear of the target mileage; The impact load spectrum set of each gear includes a plurality of impact load spectra of each gear, and the impact load spectrum set of each gear of the target mileage includes a plurality of impact load spectra of each gear of the target mileage; S5, combining the bench spectrum set of each gear position of the target mileage obtained in S3 and the impact load spectrum of each gear position of the target mileage obtained in S4 to obtain a fatigue bench spectrum set with impact load, wherein the fatigue bench spectrum set with impact load includes multiple fatigue bench spectra with impact load.

2. The bench fatigue test method based on the transmission impact load spectrum according to claim 1, characterized in that: The preprocessing in S2 specifically includes converting each load spectrum data into a standard format and converting each load spectrum data into a uniform collection frequency.

3. The bench fatigue testing method based on the transmission impact load spectrum according to claim 2, characterized in that: The standard format in S2 is ".xlsx" format, ".txt" format or ".dat" format, and the unified acquisition frequency is 1 Hz, 10 Hz or 100 Hz.

4. The bench fatigue testing method based on the transmission impact load spectrum according to claim 1, characterized in that: The step of converting the bench spectrum set to the target life mileage in S3 is specifically to multiply the acceleration time in each bench spectrum by a coefficient k, where the coefficient k=L0 / L; Among them, L represents the collected mileage, which is the sum of the vehicle speed collected by S1 multiplied by the unit time, and L0 represents the target mileage.

5. The bench fatigue testing method based on the transmission impact load spectrum according to claim 1, characterized in that: The step of converting the impact load spectrum set to the target life mileage in S4 is specifically to multiply the number of impact loads in each impact load spectrum by a coefficient k, where the coefficient k=L0 / L; Among them, L represents the collection mileage, and L0 represents the target mileage.

6. The bench fatigue testing method based on the transmission impact load spectrum according to claim 1, characterized in that: The threshold in S4 is the rated torque output by the motor.

7. The bench fatigue testing method based on the transmission impact load spectrum according to claim 1, characterized in that: In the impact load spectrum of each gear in S4, the torque change rate when the motor output torque passes through 0 is reduced.

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