A method for evaluating test results in a braking distance test

Abstract

The present invention relates to an evaluation method for test results in a braking distance test, including conducting a 100-kilometer braking distance test, obtaining test data, conducting at least 4 valid tests and taking the arithmetic mean of the 4 valid test data as the test result; dividing the entire braking stage T into three stages according to the speed of the vehicle: correcting the test results of the four stages according to their respective correction formulas; evaluating the correction results of the four stages with evaluation criteria to determine whether the results meet the preset goals of vehicle development, and appropriately optimizing the design of the vehicle according to the improvement direction. The method provides a correction formula for the test distance data of the entire stage and the three sub-stages to eliminate the deviation caused by the difference in the initial braking speed; at the same time, based on a large number of test results, an evaluation standard is proposed for the entire stage and the three sub-stages, and an improvement direction is proposed for each sub-stage, which has a positive significance for the development and progress of automobiles in terms of braking safety.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle testing, and in particular relates to a method for evaluating test results in a braking distance test. Background Art

[0002] Braking distance refers to the distance traveled by a vehicle carrying a certain load at a certain initial speed, from the moment the driver applies full braking to the moment the vehicle stops completely. Braking distance is an important indicator of the braking ability of a vehicle under emergency and extreme conditions. There are many types of braking distances in various domestic and international standards. According to the state of the powertrain, it is divided into engine disengaged state and engine engaged state. According to the different vehicle loads, it is divided into no-load braking distance and full-load braking distance. According to the initial braking speed, there are 80% of the maximum speed, 100km / h, 80km / h, 50km / h, etc. Among them, the condition of engine disengaged state, full load and initial speed of 100km / h is the most commonly used test condition by various automobile manufacturers, referred to as 100km braking distance. There are also different control values ​​for the operating force of the brake operating device. In domestic standards, the pedal force is required not to exceed 500N, and in some international standards, the maximum pedal force is 1500N.

[0003] In the 100km braking distance test, the driver manipulates the brake pedal very quickly, generally exceeding 4000N / s; at the same time, the operating force on the brake pedal is very large, generally exceeding 1000N. The braking pressure in the hydraulic braking system rises very quickly, generally exceeding 33Mpa / s; the braking pressure is very high, generally exceeding 10Mpa, and the vehicle's deceleration will also reach about 10m / s2. In the entire test, the braking time is generally around 2.5s to 3.5s, which is very short. For tests on extreme working conditions such as braking distance, the test results cannot be evaluated and analyzed from a theoretical calculation, so there are great difficulties in evaluating and analyzing the test results.

[0004] At the same time, in the braking distance test, the vehicle speed when the brake operating device is triggered (i.e. the initial braking speed) cannot be exactly the same, and the initial speed has a great influence on the test results of the braking distance. Therefore, the inconsistency of the initial braking speed brings great difficulties to the analysis of the test results. Summary of the invention

[0005] The purpose of the present invention is to provide an evaluation method for the test results in a braking distance test, so as to solve the problem that the braking distance test results are difficult to evaluate and analyze for tests under extreme conditions such as braking distance. The evaluation method divides the test results of the braking distance test into three stages, and the division point of each stage is a certain speed of the test vehicle; a correction formula is provided for the test distance data of the entire stage and the three sub-stages, so as to eliminate the deviation caused by the different initial braking speeds; at the same time, based on a large number of test results, evaluation standards are proposed for the entire stage and the three sub-stages, and improvement directions are proposed for each sub-stage, which has positive significance for the development and progress of automobile braking safety. The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for evaluating test results in a braking distance test comprises the following steps:

[0007] S1. Conduct a 100km braking distance test, obtain test data, conduct at least 4 valid tests and take the arithmetic mean of the 4 valid test data as the test result;

[0008] S2. The entire braking phase T is divided into three phases, T1 phase, T2 phase and T3 phase, according to the speed of the vehicle:

[0009] S3, correct the test results of the four stages T, T1, T2, and T3 according to their respective correction formulas;

[0010] S4. Use the evaluation criteria to evaluate the correction results of the four stages to determine whether the results meet the preset goals of vehicle development. At the same time, the vehicle design can be appropriately optimized according to the improvement direction.

[0011] Furthermore, in step S1, the test conditions are: the pedal force rising rate exceeds 4000N / s, and the maximum pedal force does not exceed 1500N.

[0012] Furthermore, in step S1, the initial braking speed of the test is 100±2km / h.

[0013] Furthermore, step S2 specifically includes the following steps:

[0014] S21, the entire braking stage T is from the initial braking moment to the moment when the vehicle speed is 0, the elapsed time is t, the braking distance is S, and the initial braking moment is determined based on objective data. At this time, the vehicle speed is the initial braking speed V0;

[0015] The S22, T1 stage is from the initial braking moment to the moment when the vehicle speed reaches (V0-1.5) km / h, the elapsed time is t1, and the braking distance in this stage is S1;

[0016] The S23, T2 stage is when the vehicle speed is (V0-1.5) km / h to (V0-10) km / h, the time elapsed is t2, and the braking distance in this stage is S2;

[0017] The S24 and T3 stages are from the time when the vehicle speed is (V0-10) km / h to the time when the vehicle speed is 0, the time elapsed is t3, and the braking distance in this stage is S3;

[0018] Furthermore, in step S21, the moment when the pedal force F=10N is defined as the braking initial moment.

[0019] Furthermore, step S3 specifically includes the following steps:

[0020] S31. During the entire braking phase, the actual braking distance of the vehicle is S 实 Corrected to the braking distance S under certain conditions with the initial braking speed:

[0021] S32, in the braking phase T1, the actual braking distance of the vehicle S 1实 Corrected to the braking distance S1 under certain conditions of the initial braking speed:

[0022] S33, in the braking stage T2, the actual braking distance of the vehicle is S 2实 Corrected to the braking distance S2 under certain conditions of the initial braking speed:

[0023] S34, in the T3 braking stage, the actual braking distance of the vehicle is S 3实 Corrected to the braking distance S3 under certain conditions of the initial braking speed:

[0024] Furthermore, step S31 is specifically as follows: during the entire braking phase, the actual braking distance S of the vehicle is calculated. 实 The braking distance S under certain conditions of the initial braking speed can be corrected by the following formula:

[0025]

[0026] Where V0 is the actual initial braking speed of the vehicle.

[0027] Furthermore, step S32 is specifically as follows: in the braking stage T1, the actual braking distance S of the vehicle is 1实 The braking distance S1 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0028]

[0029] Where V0 is the actual initial braking speed of the vehicle.

[0030] Furthermore, step S33 is specifically as follows: in the braking stage T2, the actual braking distance S of the vehicle is 2实 The braking distance S2 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0031]

[0032] Where V0 is the actual initial braking speed of the vehicle, S 3实 is the actual braking distance of the vehicle during the T3 braking phase.

[0033] Furthermore, step S34 is specifically as follows: in the braking stage T3, the actual braking distance S of the vehicle is 3实 The braking distance S3 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0034]

[0035] Where V0 is the actual initial braking speed of the vehicle.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention takes the 100-kilometer braking distance with a pedal speed exceeding 4000N / s and a pedal force not exceeding 1500N as the analysis object, and solves the problem of difficulty in evaluating and analyzing the braking distance test results by performing stage segmentation and data correction on the test data based on a large number of test statistical results. The braking distance test process is divided into three stages according to the vehicle speed, and correction formulas and evaluation criteria are provided for each stage. At the same time, the test results of each stage are provided with evaluation grades, improvement and optimization directions, which has positive significance for the development and progress of automobiles in braking safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 Schematic diagram of the entire braking phase divided into stages according to the vehicle speed. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with embodiments:

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0042] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0043] The braking distance test result evaluation method of the present invention comprises the following steps:

[0044] S1. Under the test conditions that the pedal force rising rate exceeds 4000N / s and the maximum pedal force does not exceed 1500N, conduct a 100km braking distance test. The initial braking speed of the test is 100±2km / h. Obtain test data, conduct at least 4 valid tests and take the arithmetic mean of the 4 valid test data as the test result;

[0045] S2, the entire braking stage T is divided into three stages according to the vehicle speed: stage T1, stage T2 and stage T3, such as Figure 1 As shown;

[0046] S3, correct the test results of the four stages T, T1, T2, and T3 according to their respective correction formulas;

[0047] S4. Use the evaluation criteria to evaluate the correction results of the four stages to determine whether the results meet the preset goals of vehicle development. At the same time, the vehicle design can be appropriately optimized according to the improvement direction.

[0048] Step S2 specifically includes the following steps:

[0049] S21, the entire braking stage T is from the initial braking moment to the moment when the vehicle speed is 0, the elapsed time is t, and the braking distance is S. In terms of objective data, the moment when the pedal force F=10N is defined as the initial braking moment, and the vehicle speed at this time is the initial braking speed V0;

[0050] The S22, T1 stage is from the initial braking moment to the moment when the vehicle speed reaches (V0-1.5) km / h, the elapsed time is t1, and the braking distance in this stage is S1;

[0051] The S23, T2 stage is when the vehicle speed is (V0-1.5) km / h to (V0-10) km / h, the time elapsed is t2, and the braking distance in this stage is S2;

[0052] The S24 and T3 stages are from the time when the vehicle speed is (V0-10) km / h to the time when the vehicle speed is 0, the time elapsed is t3, and the braking distance in this stage is S3;

[0053] Step S3 specifically includes the following steps:

[0054] S31. During the entire braking phase, the actual braking distance of the vehicle is S 实 The braking distance S is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0055]

[0056] Where V0 is the actual initial braking speed of the vehicle.

[0057] S32, in the braking phase T1, the actual braking distance of the vehicle S 1实 The braking distance S1 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0058]

[0059] Where V0 is the actual initial braking speed of the vehicle.

[0060] S33, in the braking stage T2, the actual braking distance of the vehicle is S 2实 The braking distance S2 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0061]

[0062] Where V0 is the actual initial braking speed of the vehicle, S 3实 is the actual braking distance of the vehicle during the T3 braking phase.

[0063] S34, in the T3 braking stage, the actual braking distance of the vehicle is S 3实 The braking distance S3 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula:

[0064]

[0065] Where V0 is the actual initial braking speed of the vehicle.

[0066] Step S4, the evaluation criteria and optimization direction are as follows:

[0067] Unit: m

[0068]

[0069]

[0070] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for evaluating test results in a braking distance test, characterized in that: The following steps are involved: S1. Conduct a 100km braking distance test, obtain test data, conduct at least 4 valid tests and take the arithmetic mean of the 4 valid test data as the test result; the test conditions are: the pedal force increase rate exceeds 4000N / s, and the maximum pedal force does not exceed 1500N; S2, dividing the entire braking stage T into three stages T1, T2 and T3 according to the speed of the vehicle: specifically comprising the following steps: S21, the entire braking stage T is from the initial braking moment to the moment when the vehicle speed is 0, the elapsed time is t, the braking distance is S, and the initial braking moment is determined based on objective data. At this time, the vehicle speed is the initial braking speed V0; The S22, T1 stage is from the initial braking moment to the moment when the vehicle speed reaches (V0-1.5) km / h, the elapsed time is t1, and the braking distance in this stage is S1; The S23, T2 stage is when the vehicle speed is (V0-1.5) km / h to (V0-10) km / h, the time elapsed is t2, and the braking distance in this stage is S2; The S24 and T3 stages are from the time when the vehicle speed is (V0-10) km / h to the time when the vehicle speed is 0, the time elapsed is t3, and the braking distance in this stage is S3; S3, the test results of the four stages T, T1, T2, and T3 are corrected according to their respective correction formulas; specifically, the following steps are included: S31. During the entire braking phase, the actual braking distance of the vehicle is S 实 Corrected to the braking distance S under a certain condition of the initial braking speed: Specifically: During the entire braking phase, the actual braking distance S of the vehicle 实 The braking distance S under certain conditions of the initial braking speed is corrected by the following formula: Where V0 is the actual initial braking speed of the vehicle. S32, in the braking phase T1, the actual braking distance of the vehicle S 1实 Corrected to the braking distance S1 under a certain condition of the initial braking speed: Specifically: in the T1 braking stage, the actual braking distance S 1实 The braking distance S1 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula: Where V0 is the actual initial braking speed of the vehicle; S33, in the braking stage T2, the actual braking distance of the vehicle is S 2实 Corrected to the braking distance S2 under a certain condition of the initial braking speed: Specifically: in the T2 braking stage, the actual braking distance S 2实 The braking distance S2 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula: Where V0 is the actual initial braking speed of the vehicle, S 3实 is the actual braking distance of the vehicle in the T3 braking stage; S34, in the T3 braking stage, the actual braking distance of the vehicle is S 3实 Corrected to the braking distance S3 under a certain condition of the initial braking speed: Specifically: in the T3 braking stage, the actual braking distance S 3实 The braking distance S3 is corrected to the braking distance of 100 km / h under the condition of initial braking speed by the following formula: Where V0 is the actual initial braking speed of the vehicle; S4. Use the evaluation criteria to evaluate the correction results of the four stages to determine whether the results meet the preset goals of vehicle development. At the same time, the vehicle design can be appropriately optimized according to the improvement direction.

2. The method for evaluating test results in a braking distance test according to claim 1, characterized in that: Step S1, the initial braking speed of the test is 100±2km / h.

3. The method for evaluating test results in a braking distance test according to claim 1, characterized in that: Step S21, defining the moment when the pedal force F=10N as the braking initial moment.

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