Limit verification method for evaluating the performance of vehicle automatic transmission cooling systems

Abstract

This invention discloses a limit verification method for evaluating the performance of a vehicle's automatic transmission cooling system. The method includes setting a test ramp and test environment, setting vehicle load and tire pressure, and conducting a parking test when the transmission oil temperature of the vehicle under test reaches thermal equilibrium. Test parameters are collected and recorded, and the equilibrium test results are recorded when the transmission oil temperature reaches thermal equilibrium. If the transmission oil temperature does not reach thermal equilibrium during the parking test, the imbalance test results are recorded. The performance of the automatic transmission cooling system of the vehicle under test is evaluated based on the setting angle of the test ramp and the test results. This invention facilitates OEMs in fully verifying the cooling performance of automatic transmissions during the vehicle development stage, eliminating problems such as powertrain torque limitation and overheating alarms caused by insufficient transmission cooling performance during vehicle use, and improving product quality.

Description

Technical Field

[0001] This invention relates to the field of vehicle performance testing technology, and more particularly to a limit verification method for evaluating the performance of a vehicle automatic transmission cooling system. Background Technology

[0002] Currently, automatic transmission-related tests focus on the design and temperature control of the transmission cooling system. The cooling of the automatic transmission cooling system affects the overall performance of the vehicle. During the vehicle development phase, OEMs need to fully verify whether the cooling performance of the automatic transmission can cover all user operating conditions, eliminate problems such as powertrain torque limiting and overheating alarms caused by insufficient transmission cooling performance during vehicle use, and improve product quality. Therefore, there is an urgent need for a cooling test, verification, and evaluation method for vehicle automatic transmission cooling systems to solve the above problems. Summary of the Invention

[0003] The purpose of this invention is to provide a limit verification method for evaluating the performance of a vehicle automatic transmission cooling system, in order to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a limit verification method for evaluating the performance of a vehicle automatic transmission cooling system, comprising:

[0005] The test ramp and test environment of the vehicle under test are set according to the verification standards. The vehicle load and tire pressure are set according to the technical conditions of the vehicle under test. The vehicle under test is a vehicle with an automatic transmission.

[0006] Preheat the vehicle under test until the engine coolant temperature, engine oil temperature and transmission fluid temperature reach thermal equilibrium.

[0007] Drive the vehicle under test to the preset position on the test slope, control the throttle opening of the vehicle under test, and start the parking slope test when the vehicle under test is stationary on the test slope.

[0008] During the hill-start test, test parameters are collected and recorded. When the transmission oil temperature reaches thermal equilibrium, the hill-start test duration is recorded as the equilibrium test result. The transmission oil temperature shall not exceed the allowable temperature.

[0009] If the transmission oil temperature does not reach thermal equilibrium during the hill-start test, until the transmission oil temperature exceeds the maximum allowable temperature, the hill-start test duration is recorded as the unbalanced test result.

[0010] The performance of the automatic transmission cooling system of the vehicle under test is evaluated based on the setting angle of the test ramp and the test results.

[0011] Furthermore, the vehicle under test is preheated until the engine coolant temperature, engine oil temperature, and transmission fluid temperature reach thermal equilibrium, including:

[0012] Thermal equilibrium is defined as a temperature increase of no more than 1°C within 4 consecutive minutes with no further upward trend.

[0013] Furthermore, the test vehicle is driven to a preset position on the test ramp, and the throttle opening of the test vehicle is controlled so that the test vehicle begins a parking slope test while remaining stationary on the test ramp. This also includes:

[0014] The vehicle under test is driven to a preset position on the test slope at a speed lower than the preset speed. The vehicle speed is then reduced to zero. The maximum throttle opening is used to keep the vehicle stationary on the test slope.

[0015] Furthermore, if the transmission oil temperature does not reach thermal equilibrium during the hill-start test, and continues until the transmission oil temperature exceeds the maximum permissible temperature, the hill-start test duration is recorded as the result of the unbalanced test, and the following is also included:

[0016] Repeat the slope test multiple times and record the test results, including the results of the equilibrium test and the results of the unequilibrium test;

[0017] The average test result is obtained by taking the arithmetic mean of the n unbalanced test results;

[0018] Confirm whether the average test result is valid. If it is valid, then the average test result is a valid test result.

[0019] Further, confirming whether the average test result is valid, and if valid, then the average test result is a valid test result, also includes calculating the standard deviation and coefficient of variation. The formula for calculating the standard deviation is:

[0020]

[0021]

[0022]

[0023] Where μ is the arithmetic mean, i is the i-th trial, and T i Let be the result of the unbalanced test in the i-th test, n be the number of unbalanced test results taken, SD be the standard deviation, and k be the coefficient of variation.

[0024] A coefficient threshold is set for the coefficient of change. When the coefficient of change calculated from the n unbalanced test results is less than the coefficient threshold, the arithmetic mean of the n unbalanced test results is taken as the average test result, which is considered a valid test result.

[0025] Furthermore, the test ramp includes a first ramp and a second ramp, wherein the ratio of the vertical height to the corresponding horizontal length of the first ramp is 3:10, and the ratio of the vertical height to the corresponding horizontal length of the second ramp is 1:5; the parking test includes a D-gear parking test and an R-gear parking test.

[0026] Furthermore, the evaluation of the automatic transmission cooling system performance of the vehicle under test, based on the setting angle of the test ramp and the test results, also includes:

[0027] If the vehicle under test is subjected to a parking test in D and R gears on the first and second slopes, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, it indicates that the transmission cooling system has excellent performance and the user will not experience transmission overheating problems during use.

[0028] If the vehicle under test performs a parking test in D and R gears on the second slope, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, and the vehicle under test performs a parking test in D and R gears on the first slope, and the parking time is not less than 300 seconds, it indicates that the transmission cooling system is performing well, and there is a small probability that the transmission will overheat during user operation.

[0029] If the vehicle performs a parking test in D and R gears on the second slope, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, and the vehicle performs a parking test in D and R gears on the first slope, and the parking time is less than 300 seconds, it indicates that the performance of the transmission cooling system is average, and there is a high probability that the transmission will overheat during use.

[0030] If the vehicle is subjected to a parking test in D and R gears on the second and first slopes, and the transmission oil temperature fails to reach thermal equilibrium during the test, it indicates that the transmission cooling performance is insufficient and cannot meet the user's needs, requiring improvement of the cooling system performance.

[0031] Furthermore, during the hill-start test, the air conditioning was turned on to maintain the interior temperature of the vehicle under test at the preset temperature.

[0032] Furthermore, setting up the test ramp and test environment for the vehicle under test according to the verification standards also includes:

[0033] The test environment requires an average wind speed of no more than 3 m / s and an ambient temperature within the range of 20℃ to 40℃.

[0034] Furthermore, setting the vehicle load and tire pressure according to the technical specifications of the vehicle under test also includes:

[0035] Loading should be performed according to the maximum design gross vehicle weight, and the vehicle load distribution should be in accordance with the vehicle's technical specifications; the vehicle tire pressure should be maintained at the specified value, with an error not exceeding ±10 kPa.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: The main purpose of the present invention is to provide an extreme verification method for evaluating the cooling performance of automatic transmissions (including three typical automatic transmissions: AT, DCT and CVT) in passenger vehicles. This allows OEMs to fully verify whether the cooling performance of the automatic transmission can cover all user operating conditions during the vehicle development stage, eliminating problems such as powertrain torque limitation and overheating alarms caused by insufficient transmission cooling performance during vehicle use, and improving product quality.

[0037] This invention, through the classification and summarization of numerous experiments and the analysis of actual user operating conditions, combined with the main factors contributing to the heat generation of automatic transmissions during vehicle use, presents a limit verification method for the cooling performance of passenger vehicle automatic transmissions. This method is simple to operate, has a short testing time, and is not demanding in terms of testing environment conditions. Any OEM has the necessary testing resources, saving OEMs R&D costs, reducing testing risks, and shortening the testing cycle. Furthermore, the steady-state testing conditions provided by this method offer easily simulcast input conditions for the development of automatic transmission cooling systems, reducing the difficulty of cooling system development and filling a gap in testing methods for OEMs in this field. Attached Figure Description

[0038] Figure 1 This is a flowchart of a limit verification method for evaluating the performance of a vehicle automatic transmission cooling system, as described in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of a vehicle parking test on the first and second ramps in an embodiment of the present invention;

[0040] Figure 3 This is a graph showing the relationship between test time and transmission oil temperature during a hill-climbing test in embodiment of the present invention, with R gear and D gear respectively in the first and second slopes. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Please refer to the accompanying drawings in the specification. This invention provides a technical solution: such as... Figure 1 As shown, a limit verification method for evaluating the performance of a vehicle automatic transmission cooling system includes the following steps:

[0045] S102. Set up the test ramp and test environment for the vehicle under test according to the verification standard, and set the vehicle load and tire pressure according to the technical conditions of the vehicle under test, wherein the vehicle under test is a vehicle with an automatic transmission.

[0046] Specifically, the test ramp includes a first ramp and a second ramp, wherein the ratio of the vertical height to the corresponding horizontal length of the first ramp is 3:10, for example... Figure 2 In the example, the first ramp has a vertical height of 30m and a horizontal length of 100m; the ratio of the vertical height to the corresponding horizontal length of the second ramp is 1:5; for example... Figure 2 In the test, the vertical height of the second ramp is 20m and the horizontal length is 100m. The slope test includes the D-gear slope test and the R-gear slope test. The length of the test ramp is not less than 10m. The road surface should be a flat, firm, dry, and uniformly sloped paved road. The first and second ramps are the optimal slopes summarized based on the user's actual usage scenarios and test experience.

[0047] If a corresponding test slope is unavailable, and the slope deviation from the required test slope is less than 5%, compensation can be made by correcting the overall vehicle test mass. The corrected mass is calculated using the following formula.

[0048] AM = (α1 - α0) × M;

[0049] In the formula:

[0050] ΔM—corrected mass, in kilograms (kg);

[0051] M – Maximum design total mass, in kilograms (kg);

[0052] a0 — Actual slope of the ramp in use, in percentage (%);

[0053] a1—Specifies the slope of the test ramp, in percentage (%);

[0054] When the calculated corrected mass ΔM is positive, the load should be increased; when it is negative, the load should be decreased.

[0055] Specifically, the test environment requires an average wind speed of no more than 3 m / s and an ambient temperature within the range of 20℃ to 40℃. The test environment requires sunny weather with plenty of sunshine and few clouds.

[0056] Specifically, the load is applied according to the maximum design gross weight of the vehicle, and the vehicle load distribution is in accordance with the vehicle's technical specifications; the tire pressure is maintained at the specified value, with an error not exceeding ±10 kPa.

[0057] Before the test, the vehicle's automatic transmission cooling system, cooling fan, radiator, etc., must be checked in accordance with the vehicle's instruction manual and relevant technical specifications. The specifications and amount of transmission oil or coolant in the automatic transmission cooling system must also be confirmed before the test.

[0058] The test conditions of this invention are based on the analysis of user operating conditions, transmission overheating principles, and the accumulation of a large amount of test data, and summarize typical test conditions.

[0059] S104. Preheat the vehicle to be tested until the engine coolant temperature, engine oil temperature and transmission fluid temperature reach thermal equilibrium.

[0060] Specifically, before the hill start test, the vehicle should be warmed up at a speed of not less than 80 km / h until the engine coolant temperature, engine oil temperature and transmission fluid temperature reach equilibrium. Generally, it is considered that the temperature has reached equilibrium if the temperature rise does not exceed 1°C within 4 consecutive minutes and there is no further upward trend.

[0061] Specifically, during the hill-start test, the air conditioning was turned on to maintain the interior temperature of the vehicle under test at the preset temperature.

[0062] During the test, the air conditioner was on. The automatic air conditioner was set to AUTO 25℃, and the manual air conditioner was set to 25℃ or medium temperature, fan speed level 3, and external circulation.

[0063] S106. Drive the vehicle under test to the preset position of the test slope, control the throttle opening of the vehicle under test, and start the parking slope test when the vehicle under test is stationary on the test slope.

[0064] Specifically, the vehicle under test is driven to a preset position on the test slope at a speed lower than the preset speed, and the vehicle speed is zero. The maximum throttle opening is used to keep the vehicle stationary, so that the vehicle under test remains stationary on the test slope.

[0065] In this test, the driver drove the vehicle uphill at a speed of less than 10 km / h. When the vehicle reached the middle of the test slope, the driver reduced the throttle opening to slow the vehicle down to 0 km / h. The driver then controlled the throttle opening to the critical state where the vehicle speed was greater than 0.5 km / h. The vehicle was then parked on the slope and kept stationary. Various measurement parameters were recorded until the transmission oil temperature reached equilibrium, i.e., the transmission oil temperature changed by less than 1°C within 4 minutes.

[0066] In the embodiments described above, if the transmission oil temperature exceeds the maximum permissible temperature, the instrument panel displays a transmission over-temperature alarm, or the vehicle rolls back down the slope even when the throttle is increased during the parking process, the test should be stopped immediately.

[0067] The vehicle's operation on a slope according to the present invention is the best method summarized from experimental experience, which can cover the most demanding user conditions.

[0068] S108. During the hill-start test, test parameters are collected and recorded. When the transmission oil temperature reaches thermal equilibrium, the hill-start test duration is recorded as the equilibrium test result. The transmission oil temperature shall not exceed the allowable temperature.

[0069] Specifically, the collected parameters and their units are shown in the table below:

[0070] Table 1 Measurement parameters, units, and accuracy range

[0071] parameter unit Accuracy time s ±0.1s temperature ℃ ±0.5℃ Atmospheric pressure kPa ±1kPa speed km / h ±0.1km / h quality kg ±5kg

[0072] The parameters are collected by sensors installed at corresponding locations on the vehicle under test. The test measurement parameters and the corresponding sensor installation locations are shown in the table below:

[0073] Table 2 Test measurement parameters and sensor installation locations

[0074]

[0075]

[0076] S110. If the transmission oil temperature does not reach thermal equilibrium during the hill-start test, until the transmission oil temperature exceeds the maximum allowable temperature, record the hill-start test duration as the unbalanced test result.

[0077] S112. Evaluate the performance of the automatic transmission cooling system of the vehicle under test based on the setting angle of the test ramp and the test results.

[0078] Optionally, if the transmission oil temperature does not reach thermal equilibrium during the hill-start test, and continues until the transmission oil temperature exceeds the maximum allowable temperature, after recording the hill-start test duration as the unbalanced test result, the following may also be included:

[0079] Repeat the slope test multiple times and record the test results, including the results of the equilibrium test and the results of the unequilibrium test;

[0080] Specifically, before repeating the next hill-start test, step S104 needs to be repeated to reheat the vehicle. The next hill-start test can only begin after the vehicle has been reheated.

[0081] The average test result is obtained by taking the arithmetic mean of the n unbalanced test results;

[0082] Specifically, for the preferred hill-climbing test where the transmission oil temperature has not reached thermal equilibrium, the test needs to be repeated 3 times at this slope, and the hill-climbing time T should be recorded for each test.

[0083] Confirm whether the average test result is valid. If it is valid, then the average test result is a valid test result.

[0084] Optionally, confirming whether the average test result is valid, and if valid, then the average test result is a valid test result, further includes calculating the standard deviation and the coefficient of variation, wherein the standard deviation is calculated using the following formula:

[0085]

[0086]

[0087]

[0088] Where μ is the arithmetic mean, i is the i-th trial, and T i Let be the result of the unbalanced test in the i-th test, n be the number of unbalanced test results taken, SD be the standard deviation, and k be the coefficient of variation.

[0089] A coefficient threshold is set for the coefficient of change. When the coefficient of change calculated from the n unbalanced test results is less than the coefficient threshold, the arithmetic mean of the n unbalanced test results is taken as the average test result, which is considered a valid test result.

[0090] Specifically, a coefficient threshold of 5% is preferably set. When n=3, a change coefficient less than 5% calculated from the results of three tests is considered a valid result. The arithmetic mean of the three slope-holding times is taken as the final test result, i.e., the valid test result. If the slope deviation from the test requirement is less than 5%, the test can be completed by adjusting the load weight, which is also a requirement based on experience.

[0091] Optionally, evaluating the performance of the automatic transmission cooling system of the vehicle under test based on the setting angle of the test ramp and the test results further includes:

[0092] If the vehicle under test is subjected to a parking test in D and R gears on the first and second slopes, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, it indicates that the transmission cooling system has excellent performance and the user will not experience transmission overheating problems during use.

[0093] If the vehicle under test performs a parking test in D and R gears on the second slope, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, and the vehicle under test performs a parking test in D and R gears on the first slope, and the parking time is not less than 300 seconds, it indicates that the transmission cooling system is performing well, and there is a small probability that the transmission will overheat during user operation.

[0094] If the vehicle performs a parking test in D and R gears on the second slope, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, and the vehicle performs a parking test in D and R gears on the first slope, and the parking time is less than 300 seconds, it indicates that the performance of the transmission cooling system is average, and there is a high probability that the transmission will overheat during use.

[0095] If the vehicle is subjected to a parking test in D and R gears on the second and first slopes, and the transmission oil temperature fails to reach thermal equilibrium during the test, it indicates that the transmission cooling performance is insufficient and cannot meet the user's needs, requiring improvement of the cooling system performance.

[0096] The evaluation method of this invention is a big data summary based on the comparison and analysis of a large amount of experimental data and the corresponding user feedback.

[0097] In the above embodiments, the main objective of the present invention is to provide an extreme verification method for evaluating the cooling performance of automatic transmissions (including three typical automatic transmissions: AT, DCT, and CVT) in passenger vehicles. This method facilitates vehicle manufacturers in fully verifying whether the cooling performance of the automatic transmission can cover all user operating conditions during the vehicle development stage, eliminating problems such as powertrain torque limitation and overheating alarms caused by insufficient transmission cooling performance during vehicle use, and improving product quality.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A limit verification method for evaluating the performance of a vehicle automatic transmission cooling system, characterized in that, include: The test ramp and test environment of the vehicle under test are set according to the verification standards. The vehicle load and tire pressure are set according to the technical conditions of the vehicle under test. The vehicle under test is a vehicle with an automatic transmission. Preheat the vehicle under test until the engine coolant temperature, engine oil temperature and transmission fluid temperature reach thermal equilibrium. Drive the vehicle under test to the preset position on the test slope, control the throttle opening of the vehicle under test, and start the parking slope test when the vehicle under test is stationary on the test slope. During the hill-start test, test parameters are collected and recorded. When the transmission oil temperature reaches thermal equilibrium, the hill-start test duration is recorded as the equilibrium test result. The transmission oil temperature shall not exceed the allowable temperature. If the transmission oil temperature does not reach thermal equilibrium during the hill-start test, until the transmission oil temperature exceeds the maximum allowable temperature, the hill-start test duration is recorded as the unbalanced test result. Repeat the slope test multiple times and record the test results, including the results of the equilibrium test and the results of the unequilibrium test; The average test result is obtained by taking the arithmetic mean of the n unbalanced test results; To confirm whether the average test result is valid, if it is valid, the average test result is considered a valid test result. The determination of a valid test result also includes calculating the standard deviation and coefficient of variation. The formula for calculating the standard deviation is: Where μ is the arithmetic mean, i is the i-th trial, and T i Let be the result of the unbalanced test in the i-th test, n be the number of unbalanced test results taken, SD be the standard deviation, and k be the coefficient of variation. A coefficient threshold is set for the coefficient of change. When the coefficient of change calculated from the n unbalanced test results is less than the coefficient threshold, the arithmetic mean of the n unbalanced test results is taken as the average test result and is considered a valid test result. The performance of the automatic transmission cooling system of the vehicle under test is evaluated based on the setting angle of the test ramp and the test results.

2. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 1, characterized in that, Preheat the vehicle under test until the engine coolant temperature, engine oil temperature, and transmission fluid temperature reach thermal equilibrium, including: Thermal equilibrium is defined as a temperature increase of no more than 1°C within 4 consecutive minutes with no further upward trend.

3. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 1, characterized in that, The test vehicle is driven to a preset position on the test ramp, and the throttle opening of the test vehicle is controlled so that the test vehicle remains stationary on the test ramp to begin the parking slope test. The test also includes: The vehicle under test is driven to a preset position on the test slope at a speed lower than the preset speed. The vehicle speed is then reduced to zero. The maximum throttle opening is used to keep the vehicle stationary on the test slope.

4. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 1, characterized in that, The test ramps include a first ramp and a second ramp, wherein the ratio of the vertical height to the corresponding horizontal length of the first ramp is 3:10, and the ratio of the vertical height to the corresponding horizontal length of the second ramp is 1:5; the slope holding test includes a D-gear slope holding test and an R-gear slope holding test.

5. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 4, characterized in that, The evaluation of the automatic transmission cooling system performance of the vehicle under test, based on the setting angle of the test ramp and the test results, also includes: If the vehicle under test is subjected to a parking test in D and R gears on the first and second slopes, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, it indicates that the transmission cooling system has excellent performance and the user will not experience transmission overheating problems during use. If the vehicle under test performs a parking test in D and R gears on the second slope, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, and the vehicle under test performs a parking test in D and R gears on the first slope, and the parking time is not less than 300 seconds, it indicates that the transmission cooling system is performing well, and there is a small probability that the transmission will overheat during user operation. If the vehicle performs a parking test in D and R gears on the second slope, and the transmission oil temperature reaches thermal equilibrium and does not exceed the maximum allowable temperature during the test, and the vehicle performs a parking test in D and R gears on the first slope, and the parking time is less than 300 seconds, it indicates that the performance of the transmission cooling system is average, and there is a high probability that the transmission will overheat during use. If the vehicle is subjected to a parking test in D and R gears on the second and first slopes, and the transmission oil temperature fails to reach thermal equilibrium during the test, it indicates that the transmission cooling performance is insufficient and cannot meet the user's needs, requiring improvement of the cooling system performance.

6. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 1, characterized in that, include: During the hill-start test, the air conditioning was turned on to maintain the interior temperature of the vehicle under test at the preset temperature.

7. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 1, characterized in that, Setting up the test ramp and test environment for the vehicle under test according to the verification standards also includes: The test environment requires an average wind speed of no more than 3 m / s and an ambient temperature within the range of 20℃ to 40℃.

8. The limit verification method for evaluating the performance of a vehicle automatic transmission cooling system according to claim 1, characterized in that, The vehicle load and tire pressure are set according to the technical specifications of the vehicle under test, and this also includes: The load is applied according to the maximum design gross weight of the vehicle, and the vehicle load distribution is in accordance with the vehicle's technical specifications. Maintain the vehicle's tire pressure at the specified value, with an error not exceeding ±10 kPa.

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