RU2783482C2 - Method for assessment of stability of movement of motor vehicle - Google Patents

Abstract

FIELD: car industry.

SUBSTANCE: invention relates to the field of testing of motor vehicles. For determination of a numerical parameter characterizing trajectory stability of a motor vehicle, when moving in conditions of high-frequency change in a vertical load on a wheel, in a method for assessment of stability of determination of impact of tires and suspension on stability of movement of a motor vehicle, tests are conducted on an even horizontal area with asphalt coating. The motor vehicle moves along corridor 1 consisting of a rectilinear section for acceleration and a section in the form of a semicircle for rotation. In a middle part of the semicircle section, across movement corridor 1, single unevenness 2 of a square section with a side of 0.05 m is installed and fixed. Moving through single unevenness of a square section excites vertical oscillations of car wheels, nature of flow of which depends on parameters of tires and suspension. The presence of oscillations leads to change in side reactions and, consequently, a trajectory of movement of tested car 3. When the motor vehicle moves, after moving through unevenness, along trajectory 4 not leaving the overall corridor, stability of movement is considered to be satisfactory. When leaving the overall corridor, trajectory 5, stability of movement is considered to be insufficient. A quantitative assessment of stability of movement is the maximum speed, at which the motor vehicle begins to leave the movement corridor at semicircle section after moving through single unevenness of a square section.

EFFECT: determination of a numerical parameter characterizing trajectory stability of a motor vehicle, when moving in conditions of high-frequency change in a vertical load on a wheel.

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Description

The present invention relates to the field of vehicle testing.

A known method for determining the effect of tires on the lateral stability of the car, which includes measuring the lateral displacement when driving along two curved trajectories. One of the trajectories is obtained by rolling the car under its own power with the wheels turned and fixed from a given position, and the other - by its forced rolling under the influence of a lateral force from the same given position. The greater the difference between the trajectories, the worse the lateral stability of the car on these tires (SU No. 385190 A1, IPC G01M 17/02, publ. 05/29/1973).

The disadvantages of the known method are the inability to determine the effect of suspension parameters on lateral stability, as well as the low accuracy of measurements due to the lack of redistribution of the load on the wheels of the car due to low speed (1-3 m/s) during the test.

A known method for determining the directional stability of the car, which involves the movement of the car on a straight horizontal section of the road, equipped with artificial bumps. During testing, the driver strives to drive the car in the middle of the lane with minimal deviations from straight-line traffic, while determining the average speed of the lateral displacement of the car and the average integral angular speed of the steering wheel. The lower the values of these parameters, the better the directional stability of the vehicle (ON 025 319-68 Cars. Estimated handling parameters. Methods of determination).

The disadvantage of the known method is the low measurement accuracy due to the significant impact on the test results of the driver's qualifications.

The closest in technical essence to the claimed invention is a method - test "turn R _n =35 m", performed in accordance with GOST 31507-2012. The test is carried out on a flat, horizontal paved area, on which a traffic corridor is marked, including a straight section for acceleration and a circular segment for turning. The vehicle is put into uniform rectilinear motion mode, then the driver quickly removes his foot from the gas pedal and begins to turn the steering wheel to perform the maneuver. The test result "turn R _n =35 m" is the highest speed of maneuver, at which there are no separation of the wheels from the road and exits of the vehicle from the traffic corridor.

The disadvantage of the known method is that the result obtained covers only the low-frequency range of the functioning of the suspension and pneumatic tires, which does not allow us to evaluate their effect on the stability properties when the vehicle is moving on an uneven road surface.

The task to be solved by the claimed invention is to expand the functionality of testing vehicles in terms of determining the impact on the stability of the movement of the characteristics of pneumatic tires and the suspension system when they operate in the high frequency range of changes in the normal load on the wheel.

The technical result, which the proposed method is aimed at, is the determination of a numerical parameter characterizing the trajectory stability of a vehicle when driving under conditions of high-frequency changes in the vertical load on the wheel.

The technical result is achieved by the fact that the method for assessing the stability of the movement of a vehicle, which provides for a series of tests of the vehicle, consisting of acceleration in a straight section and subsequent movement at a constant speed along a section of a semicircle, according to the invention, a single unevenness is installed and fixed across the traffic corridor in the middle part of the section of the semicircle of a square section, crossing which introduces the suspension into a perturbed state, when the front wheels hit a single unevenness of the square section and until the end of the test, coasting is carried out with the steering wheel in the same position, an estimated indicator is determined equal to the speed at which the vehicle begins to exit the traffic corridor on a semicircle section after moving a single square section irregularity.

A distinctive feature of the invention is the testing of a vehicle with high-frequency vertical oscillations of the suspension and tires, which provides a determination of the stability properties characteristic of driving on uneven roads.

Distinctive features of the method for assessing the stability of the movement of a vehicle are:

- location across the traffic corridor in the middle part of the semicircle section of a fixed single square-section irregularity, crossing which introduces the suspension into a perturbed state, will create a high-frequency change in the vertical load on the wheel, which is typical for driving on an uneven road surface;

- coasting with the steering wheel position unchanged from the moment the front wheels hit a single roughness of a square section and until the end of the test, it will eliminate the influence of the driver on the test results;

- determination of an estimated indicator equal to the speed at which the vehicle begins to leave the traffic corridor in the semicircle section after crossing a single square section irregularity will allow obtaining characteristics of changes in the trajectory stability properties depending on the technical condition of the suspension and tires.

The method for assessing the stability of the movement of a vehicle is explained by images that show:

in fig. 1 - scheme of the test;

in fig. 2 - the beginning of the acceleration of the vehicle on a straight section;

in fig. 3 - entry of a vehicle into a section of a semicircle;

in fig. 4 - the beginning of the movement of the wheels of the front axle through a single unevenness;

in fig. 5 - the beginning of the movement of the wheels of the rear axle through a single unevenness;

in fig. 6 - movement of the vehicle after a single unevenness;

in fig. 7 - exit of the vehicle from the semicircle section.

The method for assessing the stability of the movement of a vehicle involves performing a series of tests carried out on a flat horizontal area with an asphalt surface, on which a traffic corridor 1 is marked (see Fig. 1), including a straight section for acceleration and a section in the form of a semicircle for turning. In the middle part of the semicircle section across the movement corridor 1, a single unevenness 2 of square section with a side of 0.05 m is installed and fixed. steering wheel position. When the front wheels hit a single unevenness 2 of square section and until the end of the test, the vehicle is transferred to the coasting mode. When driving in a semicircle, the vehicle is affected by centrifugal force and counteracting lateral reactions in the contact patches of tires with the supporting surface. Moving through a single unevenness 2 of square section, vertical vibrations of the wheels of the vehicle are excited, the nature of the flow of which depends on the parameters of the tires and suspension. The presence of fluctuations leads to a change in lateral reactions and, consequently, the trajectory of the test vehicle 3. When the vehicle moves after moving the bumps along the trajectory 4, which does not leave the overall corridor, the stability of the movement is recognized as satisfactory. When leaving the overall corridor, i.e. when moving along trajectory 5, the stability of the movement is recognized as insufficient. Tests are divided into preliminary and test. Preliminary tests are carried out to determine the initial speeds of the test tests. The initial speeds of the preliminary tests are chosen such that there is no decrease in stability properties. Finish preliminary tests at a speed at which the decrease in stability properties begins to appear. The initial speed of the credit tests is taken 10% less than the speed of the end of the preliminary tests. In subsequent races, the speed is increased at intervals of 1 km / h. If in three races at the same speed there is an exit from the corridor of movement, then the tests are completed. A quantitative assessment of the stability of movement is the maximum speed at which the vehicle begins to leave the corridor of movement in the area of the semicircle after moving a single irregularity 2 of the square section.

The method for assessing the stability of the movement of a vehicle is illustrated by examples of a specific implementation.

Example 1

A vehicle of category M1 is tested with obviously faulty rear shock absorbers according to the method that implements the described method (see Fig. 2-7). Carry out preliminary tests at vehicle speeds of 20, 25, 30, 35 and 40 km/h. It has been experimentally established that at a speed of 40 km/h, the exit of a vehicle from the corridor of traffic is observed after crossing a single irregularity of a square section; at a speed of 35 km/h, the exit does not occur. The initial speed of the test tests, equal to 36 km/h, is determined as the speed of the end of the preliminary tests (40 km/h) reduced by 10%. Tests are carried out at vehicle speeds of 36, 37 and 38 km/h. It has been experimentally established that at a speed of 38 km/h, the exit of a vehicle from the corridor of traffic is observed after crossing a single irregularity of a square section; at a speed of 37 km/h, the exit does not occur. During repeated tests at a speed of 38 km/h, the exit of the vehicle from the corridor of traffic is also observed after moving over a single unevenness of a square section.

Test result (estimation of driving stability): the lower limit of the speed range at which the vehicle loses trajectory stability is 38 km/h.

Example 2

A serviceable vehicle of category Ml is tested according to the method that implements the described method. Carry out preliminary tests at vehicle speeds of 20, 25, 30, 35, 40, 45 and 50 km/h. It has been experimentally established that at a speed of 50 km/h, the exit of a vehicle from the corridor of traffic is observed after crossing a single irregularity of a square section; at a speed of 45 km/h, the exit does not occur. The initial speed of the test tests, equal to 45 km/h, is determined as the speed of the end of the preliminary tests (50 km/h) reduced by 10%. Tests are carried out at vehicle speeds of 45, 46 and 47 km/h. It has been experimentally established that at a speed of 47 km/h, the exit of a vehicle from the corridor of movement is observed after crossing a single irregularity of a square section; at a speed of 46 km/h, the exit does not occur. During repeated tests at a speed of 47 km/h, the exit of the vehicle from the traffic corridor is also observed after crossing a single square-section irregularity.

Test result (estimation of driving stability): the lower limit of the speed range at which the vehicle loses trajectory stability is 47 km/h.

The proposed invention "Method for assessing the stability of the movement of a vehicle" in comparison with the prototype "Test "turn R _n =35 m" (see GOST 31507-2012) allows:

- to determine the quantitative indicator of the impact on the stability of the vehicle, the properties of pneumatic tires and suspension, functioning with a high-frequency change in the vertical load on the wheel, for driving on an uneven road surface;

- to determine the maximum speed of a sustainable movement of a vehicle with high-frequency vertical oscillations of the suspension and pneumatic tires;

- expand the functionality of testing vehicles in terms of determining the impact on the stability of the characteristics of pneumatic tires and the suspension system when they operate in the high frequency range of changes in the normal load on the wheel.

Claims (1)

A method for assessing the stability of the movement of a vehicle, providing for a series of tests of a vehicle, consisting of acceleration in a straight section and subsequent movement at a constant speed along a section of a semicircle, characterized in that a single unevenness of a square section is installed and fixed across the corridor of movement in the middle part of the section of the semicircle, moving through which it introduces the suspension into a perturbed state, when the front wheels hit a single unevenness of a square section and until the end of the test, coasting is carried out with the steering wheel in the same position, an estimated indicator is determined equal to the speed value at which the vehicle begins to leave the traffic corridor in the semicircle section after moving a single roughness of a square section.

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