A method for evaluating vehicle hill start control quality

Abstract

The present invention proposes a vehicle hill start control quality evaluation method, which can realize objective evaluation of the vehicle hill start control quality and improve the efficiency of vehicle development and test identification. The vehicle hill start control quality evaluation method of the present invention realizes comprehensive evaluation of the vehicle hill start control quality by analyzing the changes of indicators such as the vehicle slip distance, the extreme value of the wheel speed difference, and the peak value of the engine speed drop during the vehicle hill start process, and can be applied to the hill start control quality evaluation of any equipment with a hydromechanical transmission device and vehicles with an AT transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle control, and in particular to a method for evaluating vehicle hill start control quality. Background Art

[0002] With the rapid development of the automobile industry, special vehicles with off-road roads as the main driving environment have also made great progress. However, so far, there is a lack of research and evaluation methods for automobile ramp starting in China. For example, GB / T12539 "Test Method for Automobile Climbing Steep Slope" only requires off-road vehicles to start climbing the slope after parking on the slope for 2 minutes, but there is no clear evaluation method for starting and climbing again. The lack of objective evaluation methods makes it impossible for automobile designers and users to evaluate the pros and cons of this performance of the automobile.

[0003] After searching relevant patents and literature at home and abroad, we only found "A method for evaluating the hill start of a car" (patent number 201710514019.1), which gave a subjective description of the number of hill starts completed by the vehicle within the specified time, and adverse phenomena such as abnormal noise, clutch smoke, odor, engine stalling, engine overheating, wheel slippage, and the car reversing along the slope during the vehicle starting process, but it still falls into the category of subjective evaluation. Summary of the invention

[0004] In view of this, the present invention proposes a vehicle hill start control quality evaluation method, which can achieve objective evaluation of the vehicle hill start control quality and improve vehicle development and test identification efficiency.

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A vehicle hill start control quality evaluation method of the present invention comprises the following steps:

[0007] Park the vehicle in the maximum total mass state on a ramp and keep the vehicle in the parking state;

[0008] The driver starts the vehicle on a slope and drives it smoothly to the top of the slope. When starting on a slope, the vehicle's rolling speed, the speed of the four wheels and the engine speed are measured;

[0009] The evaluation indexes are used to evaluate the quality of the vehicle hill start control, wherein the evaluation indexes include the vehicle slip distance, the extreme value of the wheel speed difference, and the peak value of the engine speed drop; if the vehicle slip distance is greater than the maximum allowable threshold, the number of vehicle start failures is accumulated and judged, and if the number of vehicle start failures is greater than 1, the vehicle hill start fails, and the vehicle hill start final score V finalIf the vehicle starts successfully, the final score of the vehicle's hill start is calculated according to the number of successful starts. If the vehicle's rolling distance is not greater than the maximum allowable threshold, the database is queried to assign scores to the evaluation indicators. Then, the weights of the evaluation indicators are set respectively. The scores of the hill start control quality evaluation indicators are calculated according to the score assignments and weights of the evaluation indicators. After completing three hill starts, the final score of the vehicle's hill start is calculated according to the number of successful starts.

[0010] Among them, the vehicle sliding distance S slide Indicates the maximum backward sliding distance of the vehicle during the ramp start process. The calculation formula is as follows:

[0011] S slide =∫v(t)dt

[0012] Where t represents time and v represents the vehicle rolling speed.

[0013] Among them, the wheel speed difference extreme value Δn slide Indicates the maximum difference in wheel speeds of the four wheels during the vehicle's ramp start process. The calculation formula is as follows:

[0014] Δn slide =max{Δn1,Δn2,…,Δn m}

[0015] Where Δn1 is Δn at time t1, Δn2 is Δn at time t2, and so on. m t m The calculation formula of Δn at the moment is as follows:

[0016] Δn=max{n lf ,n rf ,n lr ,n rr}-min{n lf ,n rf ,n lr ,n rr}

[0017] n lf Indicates the left front wheel speed, n rf Indicates the right front wheel speed, n lr Indicates the left rear wheel speed, n rr Indicates the right rear wheel speed.

[0018] Among them, the peak value of the engine speed drop Δn engine It indicates the peak value of the downward fluctuation of the engine speed during the vehicle starting process. The calculation formula is as follows:

[0019] Δn engine =n estart -n min

[0020] Where n estart is the engine speed when the vehicle starts on a slope, n min It is the minimum engine speed when the vehicle starts on a slope.

[0021] Among them, the hill start control quality evaluation index score V is calculated, and the calculation formula is as follows:

[0022]

[0023] Among them, V_S slide S is the vehicle rolling distance slide Index assignment; V_Δn slide is the wheel speed difference extreme value Δn slide Index assignment; V_Δn engine The peak value of engine speed drop Δn engine Index assignment; a1 is the vehicle slip distance S slide Evaluation index weight; a2 is the extreme value of wheel speed difference Δn slide Evaluation index weight; a3 is the peak value of engine speed drop Δn engine Evaluation indicator weight.

[0024] Among them, the final score of the vehicle ramp start is calculated according to the number of successful vehicle starts, and the calculation formula is as follows:

[0025]

[0026] Where V1 is the first hill start control quality score, V2 is the second hill start control quality score, V3 is the third hill start control quality score, and n is the number of successful hill starts.

[0027] Beneficial effects:

[0028] 1. The method for evaluating the quality of hill start control for a vehicle of the present invention realizes a comprehensive evaluation of the quality of hill start control for a vehicle by analyzing the changes in indicators such as the vehicle rolling distance, the extreme value of the wheel speed difference, and the peak value of the engine speed drop during the process of starting the vehicle on a hill. The method can be applied to the evaluation of the quality of hill start control for any equipment with a hydromechanical transmission device and a vehicle with an AT transmission.

[0029] 2. In the hill start control quality evaluation method of the present invention, the weights of indicators such as the vehicle rolling distance, tire slip rate, and engine speed drop peak value during the vehicle ramp start process are set according to the evaluation indicator weight assignment standard of the relevant evaluation vehicle model in the database, so that the vehicle hill start control quality can be accurately and comprehensively evaluated as needed.

[0030] 3. The present invention calculates the final score of the vehicle's ramp start according to the number of successful vehicle starts, thereby achieving accurate and objective evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flowchart of the vehicle hill start control quality evaluation process of the present invention.

[0032] Figure 2 A schematic diagram of calculating the vehicle rolling distance of the present invention.

[0033] Figure 3 A schematic diagram of engine speed during vehicle starting process of the present invention. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0035] The present invention provides a method for evaluating the quality of vehicle hill start control, the flow chart of which is as follows: Figure 1 As shown, the following steps are included:

[0036] Step 101, parking the vehicle on a ramp: parking the vehicle in the maximum total mass state on a ramp and keeping the vehicle in a parked state;

[0037] Step 102, vehicle ramp start and data test: the driver drives the vehicle to start on a ramp and drives smoothly to the top of the ramp; when starting on the ramp, the following data are measured: vehicle roll speed (v), vehicle four-wheel speed (left front wheel speed n lf , right front wheel speed n rf , left rear wheel speed n lr and right rear wheel speed n rr ) and engine speed (n e );

[0038] Step 103: hill start control quality evaluation index analysis: The vehicle hill start control quality evaluation index includes the vehicle rolling distance (S slide ), wheel speed difference extreme value (Δn slide ) and the peak value of engine speed drop (Δn engine ) three indicators;

[0039] Specifically, the vehicle slip distance (S slide ) represents the maximum backward sliding distance of the vehicle during the ramp start process, and the calculation formula is as follows:

[0040] S slide =∫v(t)dt

[0041] Wherein t represents time, the vehicle slip distance calculation schematic diagram of the present invention is as follows Figure 2 shown.

[0042] Wheel speed difference extreme value (Δn slide) represents the maximum difference in wheel speeds of the four wheels during the vehicle's ramp start process, and the calculation formula is as follows:

[0043] Δn slide =max{Δn1,Δn2,…,Δn m}

[0044] Where Δn1 is Δn at time t1, Δn2 is Δn at time t2, and so on. m t m The calculation formula of Δn at the moment is as follows:

[0045] Δn=max{n lf ,n rf ,n lr ,n rr}-min{n lf ,n rf ,n lr ,n rr}

[0046] Engine speed drop peak value (Δn engine ) represents the peak value of the downward fluctuation of the engine speed during the vehicle starting process, and the calculation formula is as follows:

[0047] Δn engine =n estart -n min

[0048] Where n estart is the engine speed when the vehicle starts on a slope, n min The engine speed diagram of the vehicle starting process of the present invention is as follows: Figure 3 shown.

[0049] Step 104, hill start result determination: if the vehicle rolling distance is greater than the maximum allowable threshold, execute step 109; otherwise, the start is successful, execute step 105;

[0050] Step 105, assigning a hill start control quality evaluation index: Based on the calculation result of step 103, query the database for the vehicle rolling distance (S slide ), wheel speed difference extreme value (Δn slide ) and the peak value of engine speed drop (Δn engine ) index to score and assign values, and the vehicle slip distance (S slide ) The indicator is assigned the value V_S slide ; Wheel speed difference extreme value (Δn slide ) index is assigned the value V_Δn slide ; Peak value of engine speed drop (Δn engine ) index is assigned the value V_Δnengine ;

[0051] Step 106: Setting the evaluation index weight: querying the evaluation index weight assignment standard of the relevant evaluation model in the database, setting the vehicle slip distance (S slide ) The evaluation index weight is a1, and the wheel speed difference extreme value (Δn slide ) The evaluation index weight is a2, the engine speed drop peak value (Δn engine )The evaluation index weight is a3;

[0052] Step 107, calculating the hill start control quality score: calculating the hill start control quality evaluation index score V, and the calculation formula is as follows:

[0053]

[0054] Step 108, determine the number of starts, if the number of starts is less than 3, return to step 101, otherwise, go to step 112;

[0055] Step 109, accumulating the number of failed start times: accumulating the number of failed start times of the vehicle;

[0056] Step 110, determining the number of vehicle start failures, if greater than 1, proceeding to step 111, otherwise proceeding to step 112;

[0057] Step 111: The vehicle fails to start on a hill, and the final score of the vehicle starting on a hill is V final 0 points;

[0058] Step 112, determination of final hill start score: the final hill start score of the vehicle is calculated according to the number of successful vehicle starts, and the calculation formula is as follows:

[0059]

[0060] Where V1 is the first hill start control quality score, V2 is the second hill start control quality score, V3 is the third hill start control quality score, and n is the number of successful hill starts.

[0061] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating vehicle hill start control quality, characterized in that: The steps include: Park the vehicle in the maximum total mass state on a ramp and keep the vehicle in the parking state; The driver starts the vehicle on a slope and drives it smoothly to the top of the slope. When starting on a slope, the vehicle's rolling speed, the speed of the four wheels and the engine speed are measured; The evaluation indexes are used to evaluate the quality of the vehicle hill start control, wherein the evaluation indexes include the vehicle slip distance, the extreme value of the wheel speed difference, and the peak value of the engine speed drop; if the vehicle slip distance is greater than the maximum allowable threshold, the number of vehicle start failures is accumulated and judged, and if the number of vehicle start failures is greater than 1, the vehicle hill start fails, and the vehicle hill start final score V final If the vehicle starts successfully, the final score of the vehicle's hill start is calculated according to the number of successful starts. If the vehicle's rolling distance is not greater than the maximum allowable threshold, the database is queried to assign scores to the evaluation indicators. Then, the weights of the evaluation indicators are set respectively. The scores of the hill start control quality evaluation indicators are calculated according to the score assignments and weights of the evaluation indicators. After completing three hill starts, the final score of the vehicle's hill start is calculated according to the number of successful starts.

2. The method according to claim 1, characterized in that Vehicle sliding distance S slide Indicates the maximum backward sliding distance of the vehicle during the ramp start process. The calculation formula is as follows: S slide =∫v(t)dt Where t represents time and v represents the vehicle rolling speed.

3. The method according to claim 1, characterized in that Wheel speed difference extreme value Δn slide Indicates the maximum difference in wheel speeds of the four wheels during the vehicle's ramp start process. The calculation formula is as follows: Δn slide =max{Δn1,Δn2,…,Δn m } Where Δn1 is Δn at time t1, Δn2 is Δn at time t2, and so on. m t m The calculation formula of Δn at the moment is as follows: Δn=max{n lf ,n rf ,n lr ,n rr }-min{n lf ,n rf ,n lr ,n rr } n lf Indicates the left front wheel speed, n rf Indicates the right front wheel speed, n lr Indicates the left rear wheel speed, n rr Indicates the right rear wheel speed.

4. The method according to claim 1, characterized in that Engine speed drop peak value Δn engine It indicates the peak value of the downward fluctuation of the engine speed during the vehicle starting process. The calculation formula is as follows: Δn engine =n estart -n min Where n estart is the engine speed when the vehicle starts on a slope, n min It is the minimum engine speed when the vehicle starts on a slope.

5. The method according to any one of claims 1 to 4, characterized in that: The hill start control quality evaluation index score V is calculated using the following formula: Among them, V_S slide S is the vehicle rolling distance slide Index assignment; V_Δn slide is the wheel speed difference extreme value Δn slide Index assignment; V_Δn engine The peak value of engine speed drop Δn engine Index assignment; a1 is the vehicle slip distance S slide Evaluation index weight; a2 is the extreme value of wheel speed difference Δn slide Evaluation index weight; a3 is the peak value of engine speed drop Δn engine Evaluation indicator weights.

6. The method according to claim 5, characterized in that The final score of the vehicle's ramp start is calculated based on the number of successful vehicle starts. The calculation formula is as follows: Where V1 is the first hill start control quality score, V2 is the second hill start control quality score, V3 is the third hill start control quality score, and n is the number of successful hill starts.

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