Method and device for formulating vehicle performance test working conditions

Abstract

The invention provides a method and device for formulating a vehicle performance test working condition, and the method comprises the steps: obtaining a power system thermal parameter when a vehicle runs on a target cross-country road surface, and enabling the power system thermal parameter to serve as a reference parameter; taking the reference parameter as a calibration target, debugging by adjusting the operating parameters of the rack, and when the difference between the thermal parameters of the power system obtained in the rack environment and the calibration target meets a preset condition, determining a test working condition for simulating the target off-road pavement; obtaining a power system thermal parameter of the vehicle under the test working condition; inputting the thermal parameters of the power system into a preset cooling performance analysis model, and calculating to obtain a cooling performance evaluation value; and evaluating the performance of the vehicle power assembly cooling system based on the cooling performance evaluation value. According to the invention, the real cross-country road condition is reproduced on the laboratory rack, and the accuracy of analyzing the performance of the vehicle power assembly cooling system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobiles, in particular to a method and device for formulating a vehicle performance test working condition. BACKGROUND

[0002] With the popularity of hybrid vehicles, especially hybrid off-road passenger vehicles, users have higher requirements for their performance and reliability on complex off-road surfaces. In off-road conditions, the vehicle powertrain is heavily loaded, the vehicle speed is low, and the cooling conditions are poor, which can easily cause overheating of engine, drive motor and battery components, resulting in power limit torque and functional failure, seriously affecting driving experience and safety.

[0003] Currently, the verification of the cooling performance of the powertrain of a hybrid vehicle relies on real vehicle road tests. This method is greatly affected by the environment, site and weather, has a long test cycle and high cost, and it is difficult to achieve repetition and recurrence of the working condition, which makes design defects often discovered only in the late development stage, resulting in high rectification cost and project delay. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method and device for formulating a vehicle performance test working condition to overcome at least one of the above-mentioned defects.

[0005] In a first aspect, the embodiments of the present application provide a method for formulating a vehicle performance test working condition, which comprises: obtaining a power system thermal parameter of a vehicle when driving on a target off-road surface as a benchmark parameter; adjusting the bench running parameters for debugging with the benchmark parameter as the calibration target; determining a test working condition for simulating the target off-road surface when the difference between the power system thermal parameter obtained in the bench environment and the calibration target meets a predetermined condition; obtaining a power system thermal parameter of the vehicle under the test working condition; calculating a cooling performance evaluation value according to the power system thermal parameter; and evaluating the performance of the vehicle powertrain cooling system based on the cooling performance evaluation value.

[0006] In an optional embodiment of the present application, the power system thermal parameter of the vehicle under the test working condition is obtained by: obtaining the ambient temperature, engine inlet water temperature, engine outlet water temperature, drive motor inlet water temperature, drive motor outlet water temperature, battery inlet water temperature, battery outlet water temperature, engine oil temperature, water-cooled intercooler inlet air temperature and water-cooled intercooler outlet air temperature through sensors arranged on the vehicle; and obtaining the vehicle speed, engine speed, engine torque, drive motor torque and automatic transmission oil temperature through a controller area network signal.

[0007] In an optional embodiment of the present application, the cooling performance evaluation value is calculated by the following formula:

[0008] wherein, T y represents the cooling performance evaluation value, K represents a preset reference constant, T1 represents an ambient temperature, C1 represents an influence coefficient of an engine in-out water temperature difference, Δ Ta represents an engine in-out water temperature difference, obtained by subtracting an engine in-water temperature from an engine out-water temperature, C2 represents an influence coefficient of a battery in-out water temperature difference, Δ Tb represents a battery in-out water temperature difference, obtained by subtracting a battery in-water temperature from a battery out-water temperature, C3 represents an influence coefficient of a drive motor in-out water temperature difference, Δ Tc represents a drive motor in-out water temperature difference, obtained by subtracting a drive motor in-water temperature from a drive motor out-water temperature.

[0009] In an optional embodiment of the present application, the test working condition is obtained by: setting a bench resistance based on a vehicle running resistance formula; setting an ambient temperature in an environment cabin to a predetermined temperature value; controlling the vehicle to run on the bench while adjusting a running speed of the vehicle and a loading slope of the bench; monitoring a change of at least one core temperature parameter, the core temperature parameter including at least one of an engine water temperature, a transmission oil temperature, a drive motor water temperature and a battery water temperature; determining that the core temperature parameter reaches a stable state when a change amount of the core temperature parameter in a continuous first preset time period is less than a first threshold value, and recording a stable value at this time as a simulation stable value; comparing the simulation stable value with a corresponding reference stable value in reference parameters collected on a target off-road surface; and determining that the running speed of the vehicle and the loading slope of the bench constitute the test working condition when a difference between the simulation stable value and the reference stable value is within a predetermined allowable error range.

[0010] In an optional embodiment of the present application, the running speed of the vehicle and the loading slope of the bench are adjusted by: increasing the running speed and / or the loading slope when the simulation stable value is less than the reference stable value; decreasing the running speed and / or the loading slope when the simulation stable value is greater than the reference stable value; and stopping the adjustment when the difference between the simulation stable value and the reference stable value is within the predetermined allowable error range.

[0011] In an optional embodiment of the present application, the vehicle running resistance is determined by the following formula:

[0012] wherein, F represents the vehicle running resistance, ƒ represents a rolling resistance coefficient, M represents a total vehicle mass, i represents a road slope in percentage, C dwherein C represents an air resistance coefficient, p represents an air density, m, A represents a vehicle frontal area, and V represents a vehicle speed in km / h.

[0013] In an optional embodiment of the present application, the cooling performance evaluation value is calculated by obtaining a measured stable value of at least one core temperature value of the vehicle under the test condition when the vehicle reaches a thermal equilibrium state, the core temperature value including at least one of an engine water temperature value, a transmission oil temperature value, a driving motor water temperature value, and a battery water temperature value; performing an ambient temperature correction on the measured stable value to obtain a corrected core temperature value as the cooling performance evaluation value, wherein the corrected core temperature value is obtained by subtracting a measured ambient temperature value in the test rig ambient cabin from the measured stable value and adding a preset standard ambient temperature value; and taking the corrected core temperature value as the cooling performance evaluation value.

[0014] In an optional embodiment of the present application, the performance of the vehicle powertrain cooling system is evaluated based on the cooling performance evaluation value, including: determining whether the cooling performance evaluation value is greater than a preset engineering target value; if the cooling performance evaluation value is not greater than the engineering target value, determining that the performance of the powertrain cooling system meets the design requirement; and if the cooling performance evaluation value is greater than the engineering target value, determining that the performance of the powertrain cooling system does not meet the design requirement.

[0015] In a second aspect, the embodiments of the present application further provide a vehicle performance test condition formulation device, the device comprising: a reference parameter acquisition module configured to acquire a power system thermal parameter of a vehicle when the vehicle is running on a target off-road surface as a reference parameter; a test condition determination module configured to take the reference parameter as a calibration target, to debug by adjusting test rig operating parameters, and to determine a test condition for simulating the target off-road surface when a difference between the power system thermal parameter acquired in the test rig environment and the calibration target meets a predetermined condition; a power system thermal parameter acquisition module configured to acquire a power system thermal parameter of the vehicle under the test condition; a cooling performance evaluation value obtaining module configured to calculate a cooling performance evaluation value according to the power system thermal parameter; and a performance evaluation module configured to evaluate the performance of a vehicle powertrain cooling system based on the cooling performance evaluation value.

[0016] In a third aspect, the embodiments of the present application further provide an electronic device, comprising: a processor, a memory, and a bus, the memory storing machine readable instructions executable by the processor, the processor and the memory communicating through the bus when the electronic device is running, the machine readable instructions being executed by the processor to perform the steps of the above method.

[0017] The method and device for formulating a vehicle performance test working condition provided by the embodiment of the present application obtain a power system thermal parameter of a vehicle when the vehicle is running on a target off-road surface as a benchmark parameter; the benchmark parameter is used as a calibration target, and a test working condition for simulating the target off-road surface is determined by adjusting bench running parameters when a difference between the power system thermal parameter obtained in a bench environment and the calibration target meets a predetermined condition; a power system thermal parameter of the vehicle in the test working condition is obtained; the power system thermal parameter is input into a predetermined cooling performance analysis model, and a cooling performance evaluation value is calculated; and the performance of a vehicle power assembly cooling system is evaluated based on the cooling performance evaluation value. By the present application, the real off-road surface is reproduced in the laboratory bench, and the accuracy of performance analysis on the vehicle power assembly cooling system is improved.

[0018] In order to make the above objectives, characteristics and advantages of the present application more apparent, clear and easy to understand, the following will specifically describe a preferred embodiment in conjunction with the accompanying drawings, and the detailed description is as follows. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0020] Figure 1 The flow chart of the method for formulating a vehicle performance test working condition provided by the embodiment of the present application; Figure 2 The flow chart of the method for formulating a vehicle performance test working condition provided by the embodiment of the present application; Figure 3 The flow chart of the method for formulating a vehicle performance test working condition provided by the embodiment of the present application; Figure 4 The schematic diagram of the test results provided by the embodiment of the present application; Figure 5 The structure schematic diagram of the device for formulating a vehicle performance test working condition provided by the embodiment of the present application; Figure 6 The structure schematic diagram of the electronic device provided by the embodiment of the present application. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application generally described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, every other embodiment obtained by a person skilled in the art without creative work belongs to the scope of protection of the present application.

[0022] Firstly, the application scenarios applicable to the present application are introduced. The present application can be applied to the field of automobile technology.

[0023] It is found through research that, as the driving needs of automobile users and the performance requirements for passenger cars are changing, the performance expectations of users for passenger cars are also changing to improve the off-road performance and more economical driving forms. When users drive on commonly used off-road surfaces, the powertrain is prone to overheating, resulting in powertrain torque limitation, air conditioner compressor failure or even invalidation, which affects the driving experience.

[0024] When driving on off-road surfaces, the road conditions are complex, the wheel end power of the vehicle is high, and the road resistance is large, which puts high requirements on the power performance of the hybrid vehicle and the control strategy of the powertrain.

[0025] Based on this, the embodiments of the present application provide a vehicle performance test working condition formulation method and a formulation device to solve the technical problems of difficult verification of the cooling performance of the powertrain of the hybrid off-road vehicle, long development cycle and high cost in the prior art due to the lack of effective bench test method. The method reproduces the real off-road conditions in a controllable laboratory bench environment and establishes a quantitative cooling performance analysis model, thereby improving the accuracy of analyzing the performance of the vehicle powertrain cooling system.

[0026] Please refer to Figure 1 , Figure 1 The flowchart of the vehicle performance test working condition formulation method provided by the embodiments of the present application is shown in FIG. 1. As shown in FIG. 1, the vehicle performance test working condition formulation method provided by the embodiments of the present application comprises the following steps. Figure 1 S101, obtaining a power system thermal parameter of a vehicle when driving on a target off-road surface as a reference parameter.

[0027] Firstly, a road that can typically represent the user's severe off-road use is selected to build an experimental database.

[0028] ​For example, the test road can be a guami stone road, which is a typical and specific non-paved test road often used for performance and reliability tests of vehicles, especially off-road vehicles.

[0029] “Guami stone” refers to small-sized and irregularly-shaped stones, and in engineering, the particle size thereof is usually between 5 mm and 20 mm. Such a road is not composed of naturally-formed random gravel, but is formed by screening and paving a relatively uniform gravel layer.

[0030] Then, vehicle safety inspection and site confirmation are performed according to a standard (such as GB / T 12534), and the vehicle is prepared to be full load.

[0031] Physical sensors are arranged at key positions of the vehicle, and controller area network (CAN) bus signals are collected.

[0032] Temperature parameters are used to directly evaluate the thermal state of components.

[0033] Ambient temperature: The sensor is installed in a ventilated and non-sunlight direct place to reflect the atmospheric temperature of the test environment.

[0034] Engine / drive motor / battery water inlet temperature and water outlet temperature: The sensor is installed in the water inlet and outlet pipes of the corresponding components to calculate the water temperature difference (ΔT) and directly reflect the heat dissipation load and efficiency of the components.

[0035] Engine oil temperature, automatic transmission oil temperature, and water-cooled intercooler inlet and outlet air temperature: The sensors are installed at the corresponding positions to monitor the thermal state of these key auxiliary systems.

[0036] Vehicle state parameters are used to define the working conditions and calculate the load.

[0037] Vehicle speed, engine speed, engine torque, and drive motor torque can be obtained through CAN signals, which define the dynamic running state of the vehicle in off-road conditions.

[0038] Further, the thermal parameters of the power system of the vehicle in the test working condition are obtained by the following methods: The ambient temperature, engine water inlet temperature, engine water outlet temperature, drive motor water inlet temperature, drive motor water outlet temperature, battery water inlet temperature, battery water outlet temperature, engine oil temperature, water-cooled intercooler inlet air temperature, and water-cooled intercooler outlet air temperature are obtained through the sensors arranged on the vehicle; The vehicle speed, engine speed, engine torque, drive motor torque, and automatic transmission oil temperature are obtained through the controller area network signals.

[0039] This step lays the data foundation for the entire test method and ensures the accuracy of the subsequent bench simulation.

[0040] In an optional embodiment of the present application, a large number of road tests and data statistical analysis can be used to select the most representative off-road working condition of the user road, and the data of the guami stone road are selected as the off-road working condition road test database.

[0041] The road test data collection steps are as follows: A) According to the requirements of GB / T 12534, the vehicle safety inspection and test site confirmation are carried out, and the vehicle test quality is full load quality.

[0042] B) According to the difference of the cooling medium of the hybrid passenger car, the corresponding measurement parameters are selected according to the powertrain cooling mode. The measurement parameters and the installation position of the sensor are shown in Table 1.

[0043] Table 1:

[0044] S102, taking the reference parameter as the calibration target, adjusting the bench running parameters for debugging, and when the difference between the power system thermal parameters obtained in the bench environment and the calibration target meets the predetermined condition, the test working condition for simulating the target off-road surface is determined.

[0045] The core data obtained by the road test is used to set the resistance coefficient in the environmental cabin, simulate the working condition, and compare and select the bench test working condition of the core parameters (engine water temperature, transmission oil temperature, torque, etc.).

[0046] Further, please refer to Figure 2 , Figure 2 The flowchart for obtaining the test working condition provided by the embodiment of the present application is shown in Figure 2 The test working condition is obtained by the following way: S201, setting the bench resistance based on the vehicle running resistance formula.

[0047] The vehicle off-road working condition resistance coefficient setting formula is as follows: Wherein, the vehicle running resistance is determined by the following formula:

[0048] Wherein, F represents the vehicle running resistance, ƒ represents the rolling resistance coefficient, M represents the vehicle mass, i represents the road slope, expressed in percentage, C d represents the air resistance coefficient, ρ represents the air density, meter, A represents the vehicle windward area, V represents the vehicle running speed, unit: kilometer per hour.

[0049] Here, V is the vehicle speed in kilometers per hour (km / h); f is the rolling resistance coefficient (dimensionless); M is the vehicle mass in kilograms (kg); g is the gravitational acceleration in meters per second squared (m / s 2 ), taken as 9.8066 m / s 2 ; a is the vehicle acceleration in meters per second squared (m / s 2 ); C d is the air resistance coefficient (dimensionless); p is the air density in kilograms per cubic meter (kg / m 3 ), taken as 1.093 kg / m 3 in the laboratory; A is the vehicle frontal area in square meters (m 2 ); i is the road slope in percent; In this step, a load setting basis is provided for the test bench through theoretical calculation, ensuring that the basic resistance experienced by the vehicle when running on the test bench is equivalent to that on the real road.

[0050] Further, the vehicle speed V, the road slope i, and the vehicle for testing can be selected, and the moment when there is no significant change in the core temperature (engine water temperature, transmission oil temperature, drive motor water temperature, battery water temperature) within 4 minutes min is taken as the test bench temperature stable value Tn, which is compared with the off-road working condition road collected data road benchmark stable value TL.

[0051] The test conditions are shown in Table 2 below: Table 2:

[0052] Further, the judgment process is as follows: After the process starts, first set a group of initial parameters for the test bench test. This includes an initial vehicle speed vn and an initial test bench loading slope in. The iteration number n here starts from 1, meaning this is the first debugging attempt.

[0053] Among them, using the currently set speed vn and loading slope in, control the vehicle to run on the test bench. When the monitored core temperature (such as engine water temperature) remains stable for a continuous period of time, record the temperature stable value at this time, called the test bench temperature stable value Tn. Then, compare this test bench temperature stable value Tn with the core temperature benchmark stable value TL collected on the real off-road road before and used as the calibration target.

[0054] Then, judge whether the working condition meets the requirements.

[0055] If the bench temperature stable value Tn is greater than the road benchmark stable value TL, it indicates that the thermal load generated by the current bench setting (driving speed vn and loading slope in) on the vehicle has reached or slightly exceeded the real road level. At this time, the debugging is successful, and the current set of parameters (vn, in) is officially determined as the final test working condition used to simulate the target road surface (the corresponding speed is recorded as the final driving speed vt, and the slope is recorded as the final loading slope it), and the entire debugging process is ended.

[0056] Conversely, the substandard branch: if the bench temperature stable value Tn is less than or equal to the road benchmark stable value TL, it indicates that the thermal load intensity of the current bench setting is insufficient to simulate the real road conditions, and the load needs to be increased. At this time, the system will increase the bench parameters by a predetermined step: increase the driving speed vn by 5 kilometers per hour, and increase the loading slope in by one thousandth (i.e. 0.1%). After completing the parameter adjustment, the process will return to the "record the bench temperature stable value" step, and use the updated parameters for a new round of testing and comparison, and so on, until the working condition is up to standard.

[0057] The test results are corrected according to the following formula: T= Tn – Tb + Tc Wherein, T is the corrected core temperature (engine water temperature, transmission oil temperature, drive motor water temperature, battery water temperature), unit: Celsius (℃); Tn is the core temperature (engine water temperature, transmission oil temperature, drive motor water temperature, battery water temperature), unit: Celsius (℃); Ta is the measured ambient temperature, unit: Celsius (℃); Tb is the value of 45℃ (simulated harsh off-road working condition ambient temperature).

[0058] Compare T with T 工程目标 , if T is not greater than T 工程目标 , it is judged that the cooling system of the passenger car powertrain meets the design requirements, if T is greater than T 工程目标 , it is judged that the cooling system of the passenger car powertrain does not meet the design requirements. The following data analysis model is established by reasonably adjusting the related parameters to meet the design requirements under the hybrid off-road working condition.

[0059] The specific steps are as follows: S202, set the environmental temperature in the environmental chamber to a predetermined temperature value.

[0060] The temperature of the environmental chamber is controlled at a preset temperature simulating harsh off-road environment, for example, it can be set to 45℃, which reproduces the high temperature and low wind speed of the vehicle in the real off-road harsh cooling environment.

[0061] S203, control the vehicle to run on the bench, and adjust the driving speed of the vehicle and the loading slope of the bench.

[0062] Start the vehicle on the test bench with the base resistance and ambient temperature set. At this time, the driving speed V and the loading slope i become two core variables that can be adjusted. The operator or the control system will continuously adjust these two parameters.

[0063] By adjusting V and i, the load and power output of the vehicle are dynamically changed, and the thermal load of the powertrain is accurately controlled.

[0064] S204, monitor the change of at least one core temperature parameter.

[0065] The core temperature parameter includes at least one of engine water temperature, transmission oil temperature, drive motor water temperature, and battery water temperature.

[0066] Here, the temperature signals fed back from the vehicle are monitored in real time, and the engine water temperature, transmission oil temperature, drive motor water temperature, and battery water temperature, which are key parameters directly reflecting the thermal state of the powertrain, are focused on to lock the evaluation target and ensure that the debugging process is always around the most core and most easily overheated key components.

[0067] S205, when the change of the core temperature parameter in a continuous first preset time period is less than a first threshold value, it is determined that the core temperature parameter reaches a stable state, and the stable value at this time is recorded as a simulation stable value.

[0068] When the change of the core temperature parameter in a continuous first preset time period is not less than a first threshold value, the monitoring is continued.

[0069] When the monitored core temperature parameter changes less than a first threshold value (a very small temperature fluctuation value, which can be limited according to actual conditions) in a continuous first preset time period (for example, 4 minutes), it is determined that the system reaches thermal equilibrium.

[0070] The value of the core temperature parameter at this time is recorded as a simulation stable value (such as T n ).

[0071] This step ensures that the recorded data is obtained in a stable and comparable thermal state, avoiding errors caused by transient fluctuations and ensuring the effectiveness and fairness of subsequent comparisons.

[0072] S206, compare the simulation stable value with the corresponding reference stable value in the reference parameters collected on the target off-road surface.

[0073] Compare the simulation stable value recorded in S205 with the corresponding reference stable value collected on the real road in S101.

[0074] This step is the core of the calibration process. Through comparison, the difference between the current bench simulation working condition and the real road working condition is quantified.

[0075] S207、When the difference between the simulation stability value and the reference stability value is within the predetermined allowable error range, it is determined that the driving speed and the loading slope of the current bench constitute the test working condition.

[0076] If the difference between the simulation stability value and the reference stability value is within an engineering-acceptable, predetermined allowable error range, debugging is stopped.

[0077] Finally, the group of parameters corresponding to the driving speed V and the loading slope i at the time of the current successful matching is officially determined as the test working condition for simulating the target off-road surface.

[0078] The "translation" from the real world to the laboratory is completed. A standard test procedure that is repeatable, high-fidelity, and equivalent to the key thermal state and real vehicle road test is generated, laying the foundation for subsequent batch and efficient verification.

[0079] Specifically, the driving speed of the vehicle and the loading slope of the bench are adjusted in the following way: When the simulation stability value is less than the reference stability value, increase the driving speed and / or the loading slope.

[0080] Here, the simulation stability value being less than the reference stability value means that under the current set bench working condition (V and i), the thermal load of the vehicle powertrain is lower than that on the real road. The vehicle is "not tired enough" on the bench.

[0081] In order to increase the thermal load and make it closer to the real situation, it is necessary to increase the driving speed V of the vehicle and / or increase the loading slope i of the bench.

[0082] Increasing the speed or slope will directly cause the engine, motor, and other power components to need to output more power / torque to overcome resistance, thereby generating more heat and causing the core temperature to rise.

[0083] When the simulation stability value is greater than the reference stability value, decrease the driving speed and / or the loading slope.

[0084] Here, the simulation stability value being greater than the reference stability value means that the thermal load exerted by the current bench working condition on the vehicle has exceeded the real road level. The vehicle is "more tired than on the road" on the bench.

[0085] In order to reduce the thermal load, it is necessary to reduce the driving speed V of the vehicle and / or reduce the loading slope i of the bench. Reducing the speed or slope will reduce the burden on the power components, reduce their power output and heat generation, and thus lower the core temperature.

[0086] This step can pull the system back to the state equivalent to the real road by properly reducing the load from the overload state.

[0087] When the difference between the simulated steady value and the reference steady value is detected to be within the predetermined allowable error range, stop adjusting.

[0088] Here, when the difference between the simulated steady value measured by the test bench and the reference steady value collected from the real road is reduced to within a predefined, engineering-acceptable accuracy range (i.e., the "predetermined allowable error range") after the above iterative adjustment, it is considered that the debugging target has been achieved.

[0089] Finally, stop all adjustments. The current set of parameters (driving speed V, loading slope i) is locked, which marks the end of the debugging process, determines the equivalence of the test bench simulation and the real road in terms of thermal effects, and finally outputs the reusable, high-fidelity test case.

[0090] S103, acquire the thermal parameters of the power system of the vehicle under the test case.

[0091] Under the fixed test case (i.e., fixed V and i) determined in S102, run the vehicle again, and collect a complete set of thermal parameters of the power system using the same method as S101.

[0092] The purpose of this step is to obtain the thermal state data of the vehicle under the calibrated and stable simulated test case, providing accurate input for subsequent performance evaluation.

[0093] S104, input the thermal parameters of the power system into the predetermined cooling performance analysis model to calculate the cooling performance evaluation value.

[0094] In the first embodiment, the thermal parameters of the power system are input into the predetermined cooling performance analysis model to calculate the cooling performance evaluation value.

[0095] For example, the influence coefficient can be as shown in Table 3.

[0096] Table 3

[0097] Summarize the cooling performance data analysis model.

[0098] T y = 115 + T1 + 0.8 x Δ Ta + 0.9 x Δ Tb + 0.75 x Δ Tc Wherein, T1 represents the ambient temperature, T2 represents the engine water inlet temperature, T3 represents the engine water outlet temperature, T4 represents the battery water inlet temperature, T5 represents the battery water outlet temperature, T6 represents the drive motor water inlet temperature, T7 represents the drive motor water outlet temperature, Δ Ta represents the engine water temperature difference, obtained by subtracting the engine water inlet temperature T2 from the engine water outlet temperature T3, Δ Tb represents the battery water temperature difference, obtained by subtracting the battery water inlet temperature T4 from the battery water outlet temperature T5, Δ Tc represents the drive motor water temperature difference, obtained by subtracting the drive motor water inlet temperature T6 from the drive motor water outlet temperature T7.

[0099] By judging T y and T 工程目标 , the cooling performance of the passenger car in the off-road working condition is evaluated whether it meets the design requirements, and when it does not meet the requirements, the model parameters in Table 3 can be adjusted by arranging and cooling circuit flow, such as increasing the coolant flow in the engine cooling pipeline and the power of the water pump to adjust the engine water temperature difference, to adjust the cooling capacity of the passenger car powertrain.

[0100] Further, the cooling performance analysis model calculates the cooling performance evaluation value by the following formula:

[0101] Wherein, T y represents the cooling performance evaluation value, K represents a preset reference constant, T1 represents the ambient temperature, C1 represents the influence coefficient of the engine water temperature difference, Δ Ta represents the engine water temperature difference, obtained by subtracting the engine water inlet temperature from the engine water outlet temperature, C2 represents the influence coefficient of the battery water temperature difference, Δ Tb represents the battery water temperature difference, obtained by subtracting the battery water inlet temperature from the battery water outlet temperature, C3 represents the influence coefficient of the drive motor water temperature difference, Δ Tc represents the drive motor water temperature difference, obtained by subtracting the drive motor water inlet temperature from the drive motor water outlet temperature.

[0102] Here, the ambient temperature, the engine water temperature difference, the battery water temperature difference, and the drive motor water temperature difference can be calculated from the data obtained in S103; the reference constant and the influence coefficient are model parameters determined in advance by data analysis, which quantifies the "contribution weight" of the temperature difference of different components to the overall cooling performance.

[0103] In the second embodiment, please refer to Figure 3 , Figure 3 the flowchart for calculating the cooling performance evaluation value provided by the embodiment of the present application, as Figure 3As shown, the application also calculates the cooling performance evaluation value in the following way: S301, obtain the measured stable value of at least one core temperature value when the vehicle reaches thermal equilibrium state under the test working condition.

[0104] The core temperature value includes at least one of the engine water temperature value, the transmission oil temperature value, the drive motor water temperature value, and the battery water temperature value.

[0105] This step is carried out under the test working condition (i.e. the determined driving speed V and loading slope i), and the measured stable value of the core temperature value is monitored and obtained.

[0106] Here, the core temperature value specifically refers to one or more of the engine water temperature value, the transmission oil temperature value, the drive motor water temperature value, and the battery water temperature value. These are physical quantities that directly reflect the thermal load of key components of the powertrain.

[0107] The measured stable value refers to the temperature value actually measured and recorded by the sensor when the vehicle is running on the test bench, and when the core temperature parameters change by less than a threshold value within a continuous period of time (such as 4 minutes). This ensures that the data is obtained in a stable thermal equilibrium state, avoiding the influence of transient fluctuations.

[0108] S302, perform environment temperature correction on the measured stable value to obtain the corrected core temperature value as the cooling performance evaluation value.

[0109] Among them, the corrected core temperature value is obtained by subtracting the measured environment temperature value in the test bench environment cabin from the measured stable value, and then adding a preset standard environment temperature value.

[0110] Corrected core temperature value = measured stable value - measured environment temperature value in test bench environment cabin + preset standard environment temperature value.

[0111] Here, the measured stable value is the original temperature data obtained from S301.

[0112] The measured environment temperature value in the test bench environment cabin is the actual measured environment temperature in the environment cabin during the test bench test. This value may deviate from the preset standard environment temperature.

[0113] The preset standard environment temperature value is a unified, comparative reference environment temperature, used to simulate specific harsh working conditions, for example, it can be set to 45℃. This value allows all test results to be compared fairly under the same environment reference.

[0114] The purpose of calculating the corrected core temperature value is to eliminate the evaluation deviation caused by the difference between the actual environment temperature of the test bench and the standard environment temperature. It "converts" the temperature measured under different environment temperatures to the equivalent temperature under the same standard environment temperature.

[0115] The present application ensures that the results of the bench test, which is performed at different times and in different batches, are consistent and comparable. Regardless of the actual ambient temperature in the laboratory on the day of the test, the value used for the final evaluation is the value at a standard ambient temperature (e.g. 45°C). The final corrected core temperature value itself is directly used as the cooling performance evaluation value for subsequent performance qualification.

[0116] S105, based on the cooling performance evaluation value, evaluating the performance of the vehicle powertrain cooling system.

[0117] Specifically, it is determined whether the cooling performance evaluation value is greater than a preset engineering target value.

[0118] Here, the cooling performance evaluation value is an input value, which is the final output of all the aforementioned steps. It can have two forms: T from the first embodiment calculated by the comprehensive model y .

[0119] The core temperature value T after environmental correction from the second embodiment.

[0120] The preset engineering target value is a predefined threshold value representing the upper limit of the performance of the cooling system. This target value is a technical indicator that must be met and is determined in the early development stage based on vehicle design specifications, safety margins, and performance requirements. For example, the maximum target value of the engine outlet water temperature can be specified as 115°C.

[0121] If the cooling performance evaluation value is not greater than the engineering target value, it is determined that the performance of the powertrain cooling system meets the design requirements.

[0122] When the evaluation value is less than or equal to the engineering target value, the system performance is qualified. This means that under the currently established test conditions (i.e. simulated harsh off-road conditions), the powertrain cooling system can control the temperature within the safe and design-allowed range.

[0123] This step gives a clear pass signal. This means that the powertrain cooling system of this vehicle model has passed this test and can proceed to the next development stage or be approved for mass production. This saves unnecessary follow-up verification costs and accelerates the development process.

[0124] If the cooling performance evaluation value is greater than the engineering target value, it is determined that the performance of the powertrain cooling system does not meet the design requirements.

[0125] When the evaluation value is greater than the engineering target value, the system performance is unqualified. This indicates that the cooling capacity is insufficient and cannot effectively suppress temperature rise under simulated harsh conditions, posing a risk of overheating.

[0126] Here, the design defects can be exposed in time and accurately, and the products with hidden dangers are avoided from being pushed to the market; the unqualified conclusion will trigger the optimization process.

[0127] Further, the model (T y ) of the first embodiment can further analyze which component has the largest contribution to the over-standard temperature difference (Δ Ta , ΔT b , ΔT c ), so that targeted improvement (such as increasing the power of the water pump, optimizing the size of the radiator, etc.) can be made instead of blind trial and error.

[0128] The evaluation step of the present application realizes a closed loop from complex test data to clear and reliable engineering decisions. It makes the performance acceptance criteria objective and unified, completely eliminating the ambiguity of subjective judgment. Whether it is determined to be qualified or unqualified, it provides clear action guidelines: qualified to accelerate, unqualified to optimize accurately, thereby improving the R&D efficiency and reducing the development cost and risk.

[0129] In a specific embodiment of the present application, first, step one, the test vehicle is prepared and the sensors are arranged.

[0130] The test vehicle is prepared, and the coolant is ensured to be between MIN-MAX, the engine oil and the transmission oil are at the designed required amount. The sensors are arranged according to Table 1.

[0131] Step two, for example, a certain hybrid off-road passenger vehicle has a full load mass M = 2270, wind resistance 0.385, and wind area 3.04 m². The test vehicle is tested on the Guashi road under off-road conditions, and the signals in Table 1 are collected. The measured engine outlet water temperature is 113.5, the engine inlet water temperature is 104.5, the battery inlet water temperature is 34, the battery outlet water temperature is 38, the drive motor inlet water temperature is 35, the drive motor outlet water temperature is 35.5, the average vehicle speed is 20 km / h, and the average slope is 7.5%.

[0132] Step three, the test vehicle is tested in a bench test room under simulated conditions. By adjusting V, i, and the core temperature parameter, the engine water temperature is selected. When V = 18 km / h and i = 6%, the test vehicle engine outlet water temperature is 114.5. Under this variable setting condition, other parameter test results are as shown in Table 2. Figure 4

[0133] Please refer to Figure 4 , Figure 4 the schematic diagram of the test results provided by the embodiment of the present application, Figure 4 it can be seen that the bench test can simulate the road off-road conditions under this condition.

[0134] ​Step four, powertrain cooling performance model is established, the measurement parameters and sensor installation position are shown in Table 4.

[0135] Table 4:

[0136] When the engine outlet water temperature correction temperature T > T 工程目标 , the vehicle powertrain cooling performance is unqualified, and the powertrain cooling performance needs to be optimized. The engine temperature difference is optimized by increasing the power of the water pump in the engine cooling circuit, the battery inlet and outlet water temperature difference and the drive motor inlet and outlet water temperature difference are optimized by controlling the battery cooling strategy and the drive motor torque control mode.

[0137] Further, the optimization results are shown in Table 5.

[0138] Table 5:

[0139] The final test results meet the vehicle engineering target requirements, and the powertrain cooling performance of the passenger car in the off-road working condition meets the vehicle requirements.

[0140] The application can quickly find the problems of the hybrid passenger car in the off-road working condition, such as insufficient powertrain cooling capacity, limited power, reduced air conditioning power, overheated cabin temperature, and affected driving experience. By establishing a cooling analysis model of the powertrain cooling performance of the hybrid car in the off-road working condition, the powertrain cooling capacity of the passenger car can be evaluated in advance, and the problem of insufficient cooling capacity can be solved, and the development cycle can be reduced.

[0141] In the embodiment of the application, the environmental temperature Tc of the off-road working condition is set to 45℃, the constant speed driving speed is V = 18km / h, and the slope i is 6%. The environmental temperature can also be other temperature values according to the user's use region, which can be set according to the actual situation.

[0142] The vehicle performance test working condition formulation method and device provided by the embodiment of the application solve the technical problems of the prior art, such as the difficulty in verifying the cooling performance of the hybrid off-road vehicle due to the lack of a special test method, the long development cycle, and the high cost, by constructing a complete technical closed loop of "road data collection-bench working condition calibration-model analysis and evaluation". The method reproduces the real off-road working condition in a controllable laboratory bench environment, realizes the repeatability and standardization of the test process, establishes a quantitative cooling performance analysis model and an environmental correction method, realizes the rapid and accurate performance evaluation and short board diagnosis of the powertrain cooling system, and finally forms a complete solution from working condition formulation to performance verification, which significantly improves the research and development efficiency and provides reliable data support and decision basis for the optimization design of the vehicle cooling system.

[0143] Based on the same inventive concept, the embodiment of the present application also provides a device for formulating vehicle performance test working conditions corresponding to the method for formulating vehicle performance test working conditions. Since the principle of the device in the embodiment of the present application for solving the problem is similar to the method for formulating vehicle performance test working conditions described above, the implementation of the device can be referred to the implementation of the method, and the repeated parts will not be described herein.

[0144] Please refer to Figure 5 , Figure 5 The device for formulating vehicle performance test working conditions provided in the embodiment of the present application is shown in the structural schematic diagram. As shown in Figure 5 , the device for formulating vehicle performance test working conditions 400 comprises: a reference parameter acquisition module 401 configured to acquire a power system thermal parameter of a vehicle when the vehicle is running on a target off-road surface as a reference parameter; a test working condition determination module 402 configured to take the reference parameter as a calibration target, debug by adjusting a test bench operating parameter, and determine a test working condition for simulating the target off-road surface when a difference between the power system thermal parameter acquired in a test bench environment and the calibration target meets a predetermined condition; a power system thermal parameter acquisition module 403 configured to acquire a power system thermal parameter of the vehicle in the test working condition; a cooling performance evaluation value obtaining module 404 configured to calculate a cooling performance evaluation value according to the power system thermal parameter; a performance evaluation module 405 configured to evaluate the performance of a vehicle power assembly cooling system based on the cooling performance evaluation value.

[0145] Please refer to Figure 6 , Figure 6 The structural schematic diagram of the electronic device provided in the embodiment of the present application is shown in the structural schematic diagram. As shown in Figure 6 , the electronic device 500 comprises a processor 510, a memory 520 and a bus 530.

[0146] The memory 520 stores machine readable instructions executable by the processor 510. When the electronic device 500 is running, the processor 510 and the memory 520 communicate through the bus 530. When the machine readable instructions are executed by the processor 510, the steps of the method for formulating vehicle performance test working conditions in the method embodiment shown in Figure 1 above can be performed. The specific implementation can be referred to the method embodiment, which will not be described herein.

[0147] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiment, which will not be described herein.

[0148] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. The above described device embodiments are merely schematic, for example, the division of the units is only a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be electric, mechanical or in other forms.

[0149] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. In actual implementation, some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0150] In addition, each functional unit in the embodiments of the present application can be integrated in one processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in one unit.

[0151] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a non-volatile computer readable storage medium executable by a processor. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0152] Finally, it should be noted that the above-described embodiments are merely specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit the same. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that any skilled person in the art can still modify or easily think of changes to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features, within the technical scope disclosed by the present application. The modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for determining vehicle performance test conditions, characterized in that, include: The thermal parameters of the power system when the vehicle is driving on the target off-road surface are obtained as reference parameters; Using the benchmark parameters as the calibration target, the test conditions for simulating the target off-road surface are determined by adjusting the test bench operating parameters. When the difference between the thermal parameters of the power system obtained in the test bench environment and the calibration target meets the predetermined conditions, the test conditions for simulating the target off-road surface are determined. Obtain the thermal parameters of the vehicle's powertrain under the test conditions; Based on the thermal parameters of the power system, the cooling performance evaluation value is calculated; The performance of the vehicle powertrain cooling system is evaluated based on the aforementioned cooling performance assessment values.

2. The method according to claim 1, characterized in that, The powertrain thermal parameters of the vehicle under the test conditions were obtained using the following methods: The ambient temperature, engine inlet water temperature, engine outlet water temperature, drive motor inlet water temperature, drive motor outlet water temperature, battery inlet water temperature, battery outlet water temperature, engine oil temperature, water-cooled intercooler inlet air temperature, and water-cooled intercooler outlet air temperature are obtained by sensors installed on the vehicle. Vehicle speed, engine speed, engine torque, drive motor torque, and automatic transmission oil temperature are obtained through controller area network signals.

3. The method according to claim 2, characterized in that, The cooling performance evaluation value is calculated using the following formula: Among them, T y The cooling performance evaluation value is represented by K, which represents a preset reference constant, T1 represents the ambient temperature, C1 represents the influence coefficient of the engine inlet and outlet water temperature difference, and Δ Ta The difference between the engine inlet and outlet water temperatures is represented by C2, which is obtained by subtracting the engine inlet water temperature from the engine outlet water temperature. Δ represents the influence coefficient of the battery inlet and outlet water temperature difference. Tb The battery inlet and outlet water temperature difference is obtained by subtracting the battery inlet water temperature from the battery outlet water temperature. C3 represents the influence coefficient of the drive motor inlet and outlet water temperature difference. Δ Tc This indicates the temperature difference between the inlet and outlet water of the drive motor, which is obtained by subtracting the inlet water temperature of the drive motor from the outlet water temperature.

4. The method according to claim 1, characterized in that, The test conditions were obtained in the following ways: The bench resistance was set based on the vehicle driving resistance formula. Set the ambient temperature in the environmental chamber to a predetermined value. Control the vehicle to run on the test bench, while adjusting the vehicle's speed and the test bench's loading slope; Monitor changes in at least one core temperature parameter, which includes at least one of engine coolant temperature, transmission oil temperature, drive motor coolant temperature, and battery coolant temperature. When the change in the core temperature parameter within a continuous first preset time period is less than the first threshold, it is determined that the core temperature parameter has reached a stable state, and the stable value at this time is recorded as the simulated stable value. The simulated stable value is compared with the corresponding benchmark stable value in the benchmark parameters collected on the target off-road surface; When the difference between the simulated stable value and the reference stable value is within a predetermined allowable error range, the current travel speed and loading slope of the test bench are determined to constitute the test condition.

5. The method according to claim 4, characterized in that, Adjust the vehicle's speed and the test bench's loading gradient using the following methods: When the simulated stable value is less than the benchmark stable value, increase the driving speed and / or the loading gradient; When the simulated stable value is greater than the benchmark stable value, reduce the driving speed and / or the loading gradient; Adjustment stops when the difference between the simulated stable value and the reference stable value is detected to be within the predetermined allowable error range.

6. The method according to claim 4, characterized in that, The vehicle's resistance is determined using the following formula: Where F represents vehicle running resistance, ƒ represents rolling resistance coefficient, M represents vehicle mass, i represents road gradient, expressed as a percentage, and C d The values ​​represent the air drag coefficient, ρ represents air density (meters), A represents the vehicle's frontal area, and V represents the vehicle's speed (kilometers per hour).

7. The method according to claim 1, characterized in that, The cooling performance evaluation value is calculated using the following method: Obtain a measured stable value of at least one core temperature value when the vehicle reaches thermal equilibrium under the test conditions. The core temperature value includes at least one of the engine coolant temperature, transmission oil temperature, drive motor coolant temperature, and battery coolant temperature. The measured stable value is corrected for ambient temperature to obtain a corrected core temperature value, which is used as a cooling performance evaluation value. The corrected core temperature value is obtained by subtracting the measured ambient temperature value in the test bench environment chamber from the measured stable value and adding a preset standard ambient temperature value. The corrected core temperature value is used as the cooling performance evaluation value.

8. The method according to claim 7, characterized in that, The evaluation of the vehicle powertrain cooling system performance based on the cooling performance evaluation value includes: Determine whether the cooling performance evaluation value is greater than the preset engineering target value; If the cooling performance evaluation value is not greater than the engineering target value, then the powertrain cooling system performance is determined to meet the design requirements. If the cooling performance evaluation value is greater than the engineering target value, then the powertrain cooling system performance is determined to be unsatisfactory.

9. A device for determining vehicle performance test conditions, characterized in that, include: The baseline parameter acquisition module is used to acquire the thermal parameters of the power system when the vehicle is driving on the target off-road surface as baseline parameters. The test condition determination module is used to use the benchmark parameters as the calibration target, and to adjust the bench operating parameters for debugging. When the difference between the thermal parameters of the power system obtained in the bench environment and the calibration target meets the predetermined conditions, the test condition for simulating the target off-road surface is determined. The powertrain thermal parameter acquisition module is used to acquire the powertrain thermal parameters of the vehicle under the test conditions. The cooling performance evaluation value acquisition module is used to calculate the cooling performance evaluation value based on the thermal parameters of the power system. The performance evaluation module is used to evaluate the performance of the vehicle powertrain cooling system based on the cooling performance evaluation value.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is in operation, the processor communicates with the memory via the bus, and the processor executes the machine-readable instructions to perform the steps of the method as described in any one of claims 1 to 8.

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