A test method for testing the cooling performance of an automobile power assembly

Abstract

The present application relates to a kind of automobile power assembly cooling performance test test method, more particularly to the field of automobile technology, including steps S1, the maximum speed of the temperature of environmental chamber, test field temperature and the vehicle to be measured is collected;Step S2, the test site of the vehicle to be measured is analyzed;Step S3, the vehicle to be measured is tested;Step S4, when meeting the test allowable error, test is carried out in test field, when not meeting the test allowable error, correction test is carried out;Step S5, when correction test is carried out, the equilibrium temperature of environmental chamber and test field under constant speed condition is obtained;Step S6, the equilibrium temperature difference-value-speed curve of environmental chamber and test field under constant speed condition is fitted;Step S7, the maximum speed of the vehicle to be measured is substituted into equilibrium temperature difference-value-speed curve, the equilibrium temperature difference-value of the vehicle to be measured is obtained, and the equilibrium temperature of the vehicle to be measured when maximum speed is corrected.The present application improves the accuracy and anti-interference of the test result of automobile power assembly cooling performance.

Description

Technical Field

[0001] The present invention relates to the technical field of automobiles, and particularly to a test method for the cooling performance of an automobile powertrain. Background Art

[0002] The cooling performance test of the automobile powertrain can be carried out in a high-temperature environmental chamber (or an environmental wind tunnel, hereinafter collectively referred to as the environmental chamber) or an outdoor test field (hereinafter referred to as the test field for short). Among them, the environmental chamber can arbitrarily adjust the environmental temperature within a certain range (usually 30°C to 60°C), but there are certain restrictions on the vehicle speed (usually not exceeding 160 km / h); the maximum vehicle speed of the test field can reach 250 km / h, but the environmental temperature is completely affected by the climate and is in an uncontrollable state. Before the automobiles are launched on the market, each vehicle manufacturer has to conduct the cooling performance test of the powertrain under relatively strict standard working conditions, which means that the two conditions of high temperature and high vehicle speed need to be satisfied simultaneously. For the newly launched passenger cars in recent years, the maximum vehicle speed is basically above 200 km / h, exceeding the tolerable range of the environmental chamber, and only a small part of the time in a year in the test field can ensure an environmental temperature above 35°C, and a high-temperature weather above 40°C is even rarer. As a result, within a vehicle development cycle, the window for conducting the most demanding high-temperature and high-vehicle-speed tests is very short, and it is impossible to accurately evaluate the cooling performance before the vehicle is launched, or in order to verify the high-temperature and high-vehicle-speed working conditions, the mass production time of the vehicle product is postponed.

[0003] Chinese Patent Publication No.: CN114824357A discloses a cooling system, a test method and an evaluation method for the powertrain of a hydrogen fuel cell electric vehicle. The system includes a stack cooling subsystem, a motor cooling subsystem and a power battery cooling subsystem. The test method: install sensors, start the environmental simulation laboratory to simulate the actual working conditions for testing and collect the temperature to obtain the test results. The evaluation method is that the allowable environmental temperature of the stack coolant is not lower than the limit value under the low-speed climbing and high-speed climbing conditions, and under the high-speed and idle conditions of the stack cooling subsystem, which is considered qualified; the parameters of the motor cooling system and the battery cooling system under each working condition are not greater than the limit value, which is considered qualified. This solution does not consider the influence of the external climate on the test results of the test site, and the accuracy of the test results is low. Summary of the Invention

[0004] Therefore, the present invention provides a test method for the cooling performance of an automobile powertrain to overcome the problem of low accuracy of the test results caused by the influence of the external climate on the cooling performance test of the automobile powertrain in the prior art.

[0005] To achieve the above object, the present invention provides a test method for the cooling performance of an automobile powertrain, including:

[0006] Step S1, collect the environmental chamber temperature, the test field temperature and the maximum vehicle speed of the vehicle to be tested;

[0007] Step S2: Analyze the test site of the vehicle under test based on the maximum speed of the vehicle under test.

[0008] Step S3: Conduct tests on the vehicle to be tested based on the test site obtained from the analysis;

[0009] Step S4: When the test site for the vehicle under test is a test track, analyze whether the temperature of the test track meets the test allowable error based on the test track temperature difference. If the test allowable error is met, compensate for the test results based on the test track temperature difference. If the test allowable error is not met, perform a correction test.

[0010] Step S5: During the correction test, the vehicle under test is subjected to constant speed tests in the environmental chamber and the test track to obtain the equilibrium temperature of the environmental chamber and the test track under constant speed conditions.

[0011] Step S6: Calculate the equilibrium temperature difference between the environmental chamber and the test field under constant speed conditions based on the equilibrium temperature of the environmental chamber and the test field, and fit the equilibrium temperature difference-vehicle speed curve between the environmental chamber and the test field under constant speed conditions based on the equilibrium temperature difference.

[0012] Step S7: Test the equilibrium temperature of the vehicle under test at its maximum speed under the test site temperature. Substitute the maximum speed of the vehicle under test into the equilibrium temperature difference-speed curve to obtain the equilibrium temperature difference of the vehicle under test. Then, correct the equilibrium temperature of the vehicle under test at its maximum speed based on the equilibrium temperature difference of the vehicle under test.

[0013] Furthermore, in step S1, during data collection, the ambient temperature and the test site temperature are collected by setting a temperature sensor.

[0014] Further, in step S2, when analyzing the test site of the vehicle under test, the maximum speed Vmax of the vehicle under test is compared with the maximum speed Va allowed in the environmental chamber, and the test site of the vehicle under test is determined based on the comparison result, wherein:

[0015] When Vmax > Va, the test site for the vehicle under test is determined to be the test site.

[0016] When Vmax≤Va, the test site for the vehicle under test is determined to be an environmental chamber.

[0017] Furthermore, in step S3, when the test site for the vehicle under test is an environmental chamber, the temperature of the environmental chamber is set to the preset standard test condition ambient temperature T, the vehicle speed of the vehicle under test is adjusted to Vmax, and a standard test is conducted to obtain the thermal equilibrium temperature ts. The thermal equilibrium temperature ts is used as the test result of the powertrain cooling performance under standard conditions.

[0018] Further, in step S4, when the test site for the vehicle under test is a test track, the test track temperature difference ΔTb is calculated based on the test track temperature Tb, and ΔTb is set to |Tb-T|, where T is the preset standard test condition ambient temperature. The test track temperature difference ΔTb is compared with the preset temperature difference ΔT0, and the test track temperature is judged according to the comparison result to determine the allowable error of the test track temperature, wherein:

[0019] When △Tb≤△T0, the test site temperature is deemed to meet the allowable test error.

[0020] When △Tb>△T0, the test site temperature is determined to be inconsistent with the allowable test error, and a correction test is carried out.

[0021] Further, in step S4, when the test site temperature meets the test allowable error, the vehicle speed of the vehicle under test is adjusted to Vmax, and a test site working condition test is conducted to obtain the test site thermal balance temperature tbs1. The test site thermal balance temperature tbs1 is compensated according to the test site temperature difference ΔTb to obtain the compensated test site thermal balance temperature tbs2. tbs2 is set to tbs1 + ΔTb, and the compensated test site thermal balance temperature tbs2 is used as the test result of the powertrain cooling performance under the standard working condition of the test site.

[0022] Further, in step S5, during the correction test, the vehicle under test is subjected to n constant speed tests in the environmental chamber and the test track, where n > 1. During the constant speed test, the vehicle speed is set to Vi, and the environmental chamber temperature Ta and the test track temperature Tb are set to be the same. Under constant speed conditions, the test conditions are tested in the environmental chamber and the test track respectively. The equilibrium temperature ta i of the vehicle under test in the environmental chamber and the equilibrium temperature tb i of the vehicle under test in the test track are obtained, where i = 1, 2, ..., n, and n is the number of tests. Vi is set to V0 + (n-1) × Vd, where V0 is the preset initial vehicle speed, Vd is the preset test speed difference, Vi ≤ Va, and when i = 1, V1 ≥ 80 km / h.

[0023] Further, in step S6, when fitting the equilibrium temperature difference-vehicle speed curve Δt=f(v) between the environmental chamber and the test track under constant speed conditions, the equilibrium temperature difference Δti of the constant speed test is calculated based on the equilibrium temperature ta i of the vehicle under test in the environmental chamber and the equilibrium temperature tbi i of the vehicle under test in the test track. Δti=│ta i-tbi│ is set, and the equilibrium temperature difference-vehicle speed curve Δt=f(v) between the environmental chamber and the test track under constant speed conditions is fitted based on the equilibrium temperature difference Δti and the vehicle speed Vi of the vehicle under test.

[0024] Further, in step S7, when correcting the equilibrium temperature of the vehicle under test at its maximum speed, the equilibrium temperature Tbs of the vehicle under test at the test site temperature Tb and the maximum speed Vmax is obtained, and the maximum speed Vmax of the vehicle under test is substituted into the equilibrium temperature difference-speed curve to obtain the equilibrium temperature difference Δtmax of the vehicle under test at its maximum speed Vmax, Δtmax=f(Vmax).

[0025] Furthermore, in step S7, the corrected equilibrium temperature is Tbs', and Tbs' is set to Tbs + Δtmax. The corrected equilibrium temperature Tbs' is used as the test result of the powertrain cooling performance under standard operating conditions at the test site.

[0026] Compared with existing technologies, the beneficial effects of this invention are as follows: by collecting ambient chamber temperature, test track temperature, and the maximum speed of the vehicle under test, and combining this with actual conditions to conduct automotive powertrain cooling performance tests, the accuracy and anti-interference capabilities of the test results are improved. Furthermore, by analyzing the test site based on the maximum speed of the vehicle under test, a suitable test site is selected, further improving the accuracy and anti-interference capabilities of the test results. The vehicle under test is then tested at the analyzed test site. When the test site is a test track, the temperature difference within the test track is analyzed to determine if the test track temperature meets the allowable error. If the allowable error is met, the test proceeds... The test is conducted on-site, and corrective tests are performed when the allowable error is not met. This corrects errors caused by weather or site conditions, further improving the accuracy and anti-interference of the test results for the vehicle powertrain cooling performance. During the corrective test, the vehicle under test is subjected to constant-speed tests in both an environmental chamber and a test track to obtain the equilibrium temperature under constant-speed conditions. The temperature difference between the environmental chamber and the test track under constant-speed conditions is calculated based on the equilibrium temperature difference, and a temperature difference-vehicle speed curve is fitted to correct the test results, further improving the accuracy and anti-interference of the test results for the vehicle powertrain cooling performance. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the testing method for the cooling performance of an automotive powertrain in this embodiment. Detailed Implementation

[0028] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0029] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0030] Please see Figure 1 As shown, this is a flowchart illustrating the testing method for the cooling performance of an automotive powertrain in this embodiment. The method includes:

[0031] Step S1: Collect the ambient temperature, test site temperature, and maximum speed of the vehicle under test;

[0032] Step S2: Analyze the test site of the vehicle under test based on the maximum speed of the vehicle under test.

[0033] Step S3: Conduct tests on the vehicle to be tested based on the test site obtained from the analysis;

[0034] Step S4: When the test site for the vehicle under test is a test track, analyze whether the temperature of the test track meets the test allowable error based on the test track temperature difference. If the test allowable error is met, compensate for the test results based on the test track temperature difference. If the test allowable error is not met, perform a correction test.

[0035] Step S5: During the correction test, the vehicle under test is subjected to constant speed tests in the environmental chamber and the test track to obtain the equilibrium temperature of the environmental chamber and the test track under constant speed conditions.

[0036] Step S6: Calculate the equilibrium temperature difference between the environmental chamber and the test field under constant speed conditions based on the equilibrium temperature of the environmental chamber and the test field, and fit the equilibrium temperature difference-vehicle speed curve between the environmental chamber and the test field under constant speed conditions based on the equilibrium temperature difference.

[0037] Step S7: Test the equilibrium temperature of the vehicle under test at its maximum speed under the test site temperature. Substitute the maximum speed of the vehicle under test into the equilibrium temperature difference-speed curve to obtain the equilibrium temperature difference of the vehicle under test. Then, correct the equilibrium temperature of the vehicle under test at its maximum speed based on the equilibrium temperature difference of the vehicle under test.

[0038] Specifically, in step S1, during data collection, the ambient temperature of the test chamber and the test site temperature are collected by a temperature sensor. It is understood that this embodiment does not specify the method for collecting the maximum speed of the vehicle under test. Those skilled in the art can set it freely, such as obtaining the maximum speed of the vehicle under test by uploading data by the experimenter, as long as the requirement for accurate data collection is met.

[0039] Specifically, the environmental chamber refers to an indoor high-temperature environment where vehicles conduct powertrain cooling performance tests. The environmental chamber can adjust the ambient temperature arbitrarily within a temperature range, typically 30-60 degrees Celsius. The environmental chamber has speed restrictions; the maximum speed inside the environmental chamber typically cannot exceed 160 km / h. The test track refers to an outdoor location where vehicles conduct powertrain cooling performance tests. The ambient temperature of the test track is the outdoor temperature, and due to climate influences, the maximum speed of the test track is not restricted.

[0040] Specifically, this embodiment is applied to the process of testing the cooling performance of automotive powertrains to correct the test results. It can be applied to intelligent testing terminals in testing sites, as well as to other equipment. Taking the application to intelligent testing terminals in testing sites as an example, the intelligent testing terminal analyzes the testing site of the automotive powertrain cooling performance test and compensates and corrects the test results according to the actual situation of the testing site, thereby correcting the test results of the automotive powertrain cooling performance test to improve the accuracy and anti-interference of the test results.

[0041] Specifically, by collecting data on ambient chamber temperature, test track temperature, and the maximum speed of the vehicle under test, the cooling performance of the automotive powertrain is tested in accordance with actual conditions. This improves the accuracy and anti-interference capability of the test results. The test site is analyzed based on the maximum speed of the vehicle under test, allowing for the selection of a suitable test site, further enhancing the accuracy and anti-interference capability of the test results. The vehicle under test is then tested at the analyzed test site. When the test site is the test track, the temperature difference within the test track is analyzed to determine if the temperature meets the allowable error. If the allowable error is met, the test is conducted at the test track. When the allowable error of the test is not met, a correction test is conducted to correct the error caused by weather or site conditions during the test, thereby further improving the accuracy and anti-interference of the test results of the automotive powertrain cooling performance. During the correction test, the vehicle under test is subjected to constant speed tests in an environmental chamber and a test track to obtain the equilibrium temperature of the environmental chamber and the test track under constant speed conditions. The equilibrium temperature difference between the environmental chamber and the test track under constant speed conditions is calculated based on the equilibrium temperature difference, and a curve of equilibrium temperature difference between the environmental chamber and the test track under constant speed conditions and vehicle speed is fitted based on the equilibrium temperature difference, thereby correcting the test results and further improving the accuracy and anti-interference of the test results of the automotive powertrain cooling performance.

[0042] Specifically, in step S2, when analyzing the test site of the vehicle under test, the maximum speed Vmax of the vehicle under test is compared with the maximum speed Va allowed in the environmental chamber, and the test site of the vehicle under test is determined based on the comparison result, wherein:

[0043] When Vmax > Va, the test site for the vehicle under test is determined to be the test site.

[0044] When Vmax≤Va, the test site for the vehicle under test is determined to be an environmental chamber.

[0045] Specifically, in step S3, when the test site for the vehicle under test is an environmental chamber, the temperature of the environmental chamber is set to the preset standard test condition ambient temperature T, the vehicle speed of the vehicle under test is adjusted to Vmax, and a standard test is conducted to obtain the thermal equilibrium temperature ts. The thermal equilibrium temperature ts is used as the test result of the powertrain cooling performance under standard conditions.

[0046] Specifically, the automotive powertrain refers to a series of components that generate power in a vehicle and transmit it to the road surface. It consists of an engine, clutch, transmission, universal joint drive shaft, final drive, differential, and drive wheels. The automotive powertrain cooling system includes an engine cooling system, a transmission cooling system, and an intake turbocharger cooling system. In this embodiment, the performance of the automotive powertrain cooling system is tested through experiments. The test method for the automotive powertrain cooling performance test in this embodiment can be an environmental wind tunnel test method or other methods.

[0047] Specifically, in step S4, when the test site for the vehicle under test is a test track, the test track temperature difference ΔTb is calculated based on the test track temperature Tb. ΔTb is set to |Tb-T|, where T is the preset standard test condition ambient temperature. The test track temperature difference ΔTb is compared with the preset temperature difference ΔT0, and the allowable error of the test track temperature is judged based on the comparison result.

[0048] When △Tb≤△T0, the test site temperature is deemed to meet the allowable test error.

[0049] When △Tb>△T0, the test site temperature is determined to be inconsistent with the allowable test error, and a correction test is carried out.

[0050] Specifically, in step S4, when the test site temperature meets the allowable test error, the vehicle speed of the vehicle under test is adjusted to Vmax, and a test site working condition test is conducted to obtain the test site thermal balance temperature tbs1. The test site thermal balance temperature tbs1 is compensated according to the test site temperature difference ΔTb to obtain the compensated test site thermal balance temperature tbs2. tbs2 is set to tbs1 + ΔTb, and the compensated test site thermal balance temperature tbs2 is used as the test result of the powertrain cooling performance under the standard working condition of the test site.

[0051] Specifically, in step S5, during the correction test, the vehicle under test undergoes n constant-speed tests in the environmental chamber and the test track, where n > 1. During the constant-speed test, the vehicle speed is set to Vi, and the environmental chamber temperature Ta and the test track temperature Tb are set to be the same. Under constant-speed conditions, working condition tests are conducted in the environmental chamber and the test track respectively to obtain the equilibrium temperature ta i of the vehicle under test in the environmental chamber and the equilibrium temperature tbi of the vehicle under test in the test track, where i = 1, 2, ..., n, and n is the number of tests. Vi is set to V0 + (n-1) × Vd, where V0 is the preset initial vehicle speed, Vd is the preset test speed difference, Vi ≤ Va, and when i = 1, V1 ≥ 80 km / h.

[0052] Specifically, this embodiment does not impose a specific limitation on the preset test speed interval Vd. Those skilled in the art can set it freely, as long as it meets the requirements for differentiating vehicle speeds, such as setting Vd = 10km / h.

[0053] Specifically, in step S6, when fitting the equilibrium temperature difference-vehicle speed curve Δt = f(v) between the environmental chamber and the test track under constant speed conditions, the equilibrium temperature difference Δti of the constant speed test is calculated based on the equilibrium temperature tai of the vehicle under test in the environmental chamber and the equilibrium temperature tbi of the vehicle under test in the test track. Δti is set to |tai - tbi|, and the equilibrium temperature difference Δti and the vehicle speed of the vehicle under test are respectively set to Vi to fit the equilibrium temperature difference-vehicle speed curve Δt = f(v) between the environmental chamber and the test track under constant speed conditions.

[0054] Specifically, this embodiment does not impose specific limitations on the fitting method of the equilibrium temperature difference-vehicle speed curve Δt = f(v). Those skilled in the art can freely set it, as long as the square of the fitted curve R approaches 1. For example, when the vehicle speeds are 100, 120, 140, 160, and 210, the ΔT values ​​are 2.1, 2.6, 3.9, 5.2, and 10.6, respectively. The five sets of data are fitted, and the curve with R squared of 0.9945 is selected as the equilibrium temperature difference-vehicle speed curve Δt = f(v), with the relationship Δt = 0.0005v. 2-0.077v+4.76, where R square refers to the ratio of the regression sum of squares to the total sum of squares, representing the proportion of the total sum of squares that can be explained by the regression sum of squares. R square is between 0 and 1, and the closer it is to 1, the better the regression fit.

[0055] Specifically, in step S7, when correcting the equilibrium temperature of the vehicle under test at its maximum speed, the equilibrium temperature Tbs of the vehicle under test at the test site temperature Tb and the maximum speed Vmax is obtained. The maximum speed Vmax of the vehicle under test is then substituted into the equilibrium temperature difference-speed curve to obtain the equilibrium temperature difference Δtmax of the vehicle under test at its maximum speed Vmax, where Δtmax = f(Vmax). The corrected equilibrium temperature is Tbs', and Tbs' = Tbs + Δtmax is set. The corrected equilibrium temperature Tbs' is used as the test result of the powertrain cooling performance under standard operating conditions at the test site.

[0056] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A test method for the cooling performance of an automotive powertrain, characterized in that, include, Step S1: Collect the ambient temperature, test site temperature, and maximum speed of the vehicle under test; Step S2: Analyze the test site of the vehicle under test based on the maximum speed of the vehicle under test. Step S3: Conduct tests on the vehicle to be tested based on the test site obtained from the analysis; Step S4: When the test site for the vehicle under test is a test track, analyze whether the temperature of the test track meets the test allowable error based on the test track temperature difference. If the test allowable error is met, compensate for the test results based on the test track temperature difference. If the test allowable error is not met, perform a correction test. Step S5: During the correction test, the vehicle under test is subjected to constant speed tests in the environmental chamber and the test track to obtain the equilibrium temperature of the environmental chamber and the test track under constant speed conditions. Step S6: Calculate the equilibrium temperature difference between the environmental chamber and the test field under constant speed conditions based on the equilibrium temperature of the environmental chamber and the test field, and fit the equilibrium temperature difference-vehicle speed curve between the environmental chamber and the test field under constant speed conditions based on the equilibrium temperature difference. Step S7: Test the equilibrium temperature of the vehicle under test at its maximum speed under the test site temperature. Substitute the maximum speed of the vehicle under test into the equilibrium temperature difference-speed curve to obtain the equilibrium temperature difference of the vehicle under test. Then, correct the equilibrium temperature of the vehicle under test at its maximum speed based on the equilibrium temperature difference of the vehicle under test.

2. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S1, during data collection, the ambient temperature and the test site temperature are collected by setting a temperature sensor.

3. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S2, when analyzing the test site of the vehicle under test, the maximum speed Vmax of the vehicle under test is compared with the maximum speed Va allowed in the environmental chamber, and the test site of the vehicle under test is determined based on the comparison result, wherein: When Vmax > Va, the test site for the vehicle under test is determined to be the test site. When Vmax≤Va, the test site for the vehicle under test is determined to be an environmental chamber.

4. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S3, when the test site for the vehicle under test is an environmental chamber, the temperature of the environmental chamber is set to the preset standard test condition ambient temperature T, the vehicle speed of the vehicle under test is adjusted to Vmax, and a standard test is conducted to obtain the thermal equilibrium temperature ts. The thermal equilibrium temperature ts is used as the test result of the powertrain cooling performance under standard conditions.

5. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S4, when the test site for the vehicle under test is a test track, the test track temperature difference ΔTb is calculated based on the test track temperature Tb. ΔTb is set to |Tb-T|, where T is the preset standard test condition ambient temperature. The test track temperature difference ΔTb is compared with the preset temperature difference ΔT0, and the allowable error of the test track temperature is judged based on the comparison result. When △Tb≤△T0, the test site temperature is deemed to meet the allowable test error. When △Tb>△T0, the test site temperature is determined to be inconsistent with the allowable test error, and a correction test is carried out.

6. The test method for automotive powertrain cooling performance according to claim 5, characterized in that, In step S4, when the test site temperature meets the test allowable error, the vehicle speed of the vehicle under test is adjusted to Vmax, and a test site working condition test is conducted to obtain the test site thermal balance temperature tbs1. The test site thermal balance temperature tbs1 is compensated according to the test site temperature difference ΔTb to obtain the compensated test site thermal balance temperature tbs2. tbs2 is set to tbs1 + ΔTb, and the compensated test site thermal balance temperature tbs2 is used as the test result of the powertrain cooling performance under the standard working condition of the test site.

7. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S5, during the correction test, the vehicle under test is subjected to n constant speed tests in the environmental chamber and the test track, where n > 1. During the constant speed test, the vehicle speed is set to Vi, and the environmental chamber temperature Ta and the test track temperature Tb are set to be the same. Under constant speed conditions, the test conditions are tested in the environmental chamber and the test track respectively. The equilibrium temperature tai of the vehicle under test in the environmental chamber and the equilibrium temperature tbi of the vehicle under test in the test track are obtained, where i = 1, 2, ..., n, and n is the number of tests. Vi is set to V0 + (n-1) × Vd, where V0 is the preset initial vehicle speed, Vd is the preset test speed difference, Vi ≤ Va, and when i = 1, V1 ≥ 80 km / h.

8. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S6, when fitting the equilibrium temperature difference-vehicle speed curve Δt = f(v) between the environmental chamber and the test track under constant speed conditions, the equilibrium temperature difference Δti of the constant speed test is calculated based on the equilibrium temperature tai of the vehicle under test in the environmental chamber and the equilibrium temperature tbi of the vehicle under test in the test track. Δti is set to |tai-tbi|, and the equilibrium temperature difference-vehicle speed curve Δt = f(v) between the environmental chamber and the test track under constant speed conditions is fitted based on the equilibrium temperature difference Δti and the vehicle speed Vi of the vehicle under test.

9. The test method for automotive powertrain cooling performance according to claim 1, characterized in that, In step S7, when correcting the equilibrium temperature of the vehicle under test at its maximum speed, the equilibrium temperature Tbs of the vehicle under test at the test site temperature Tb and the maximum speed Vmax is obtained. The maximum speed Vmax of the vehicle under test is then substituted into the equilibrium temperature difference-speed curve to obtain the equilibrium temperature difference Δtmax of the vehicle under test at its maximum speed Vmax, where Δtmax = f(Vmax).

10. The test method for automotive powertrain cooling performance according to claim 9, characterized in that, In step S7, the corrected equilibrium temperature is Tbs', and Tbs' is set to Tbs + Δtmax. The corrected equilibrium temperature Tbs' is used as the test result of the powertrain cooling performance under standard operating conditions at the test site.

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