RU2096750C1 - Testing bed method determining mechanical losses in tires - Google Patents

Abstract

FIELD: tests of wheels of motor vehicles, in particular, wheels with rubber pneumatics. SUBSTANCE: test of system "roller testing bed - wheel" is carried out in two stages. At first stage losses in system are determined with the use of nondeformed analog of wheel. At second stage losses in system are found with its spinning together with tested wheel. Loses in tire are determined by difference of results of tests at second and first stages. EFFECT: enhanced reliability of method. 1 cl, 2 dwg

Description

 The invention relates to the field of testing wheels of vehicles, in particular wheels with rubber pneumatics. The invention can be used in automobile and tractor manufacturing.

 There is a method of testing wheels with tires, when the pneumatic tire is pressed to the surface of the movable support, after which a vertical load is applied to the axes of the test object, and the movable support is successively subjected to efforts in accordance with the given experiment program [1]. Using this method involves considerable technical difficulties. implementation, the method is not sufficiently operational. All this complicates its practical implementation. In addition, this method also does not take into account the peculiarity of tire deformation on the roller stand.

 The closest technical solution is a method for determining the wheel power of a car on a roller stand [2] where, according to the accepted test method, the relative mechanical losses in the roller stand are represented by a constant coefficient that determines the share of losses in the stand from the transmitted power. In fact, losses in the stand cannot be reliably determined using a constant coefficient, because they (losses) significantly depend on a number of factors: on the technical condition of the stand, which changes during its operation, in particular, due to wear of the elements of the stand); on the size of the wheel mounted on the rollers of the stand, and the geometric parameters of the latter; the magnitude of the vertical load acting on the wheel stand roller system. Therefore, this method cannot accurately determine the amount of mechanical loss in the tire.

 The aim of the invention is to improve the accuracy and efficiency of determining mechanical losses in the tire.

This goal is achieved in that the test system roller stand - wheel is carried out in two stages: at the first stage (calibration of the stand) determine the loss in the system when used as a wheel of its non-deformable analogue, record the loss in the system in the form of the dependence of the moment M _{C1 of the} resistance of the system to rolling from vertical load G _H on the wheel; at the second stage, the wheel test system is tested using the same test bench, on which instead of a non-deformable analogue a test wheel with a deformable tire is installed, the tests are carried out according to the same program and the second dependence of the rolling resistance of the system M _C2 on the vertical load G _H and on the difference the moments of resistance at the second and first stages of testing the system of the roller stand wheel determine the mechanical loss in the tire in the form of moment of resistance M _C3 from the vertical load:
M _C3 f (G _H ) M _C2 -M _C1 .

 Thus, the influence on the value of mechanical losses in the stand of its technical condition and the geometric parameters of the system of the roller wheel stand is taken into account.

 Scrolling the system of the wheel stand wheel with a non-deformable analogue provides an accurate determination of mechanical losses in the stand itself under conditions as close as possible to the impact on the stand from the side of the particular test wheel with the tire, which allows you to separate the mechanical losses in the tire and in the stand.

М_C P_C • R;
где P_C сила сопротивления качению колеса;
М_C момент сопротивления прокручиванию системы роликовый стенд - колесо;
f_k коэффициент сопротивления качению;
G_H вертикальная нагрузка на колесо (на систему роликовый стенд - колесо).Power dependencies in the system of the roller stand wheel, taking into account their geometric dimensions are determined by the following formulas (see. Fig. 1):

M _C P _C • R;
where P _{C is} the rolling resistance force of the wheel;
M _{C the} moment of resistance to rolling the system of the roller stand - wheel;
f _k rolling resistance coefficient;
G _H vertical load on the wheel (on the roller stand-wheel system).

где L межосевое расстояние роликов стенда;
R радиус качения испытуемого колеса с шиной (радиус деформируемого аналога колеса);
r радиус ролика стенда.From the geometry of the roller stand and the test wheel follows (see figure 1):
L = 2 (R + r) • sinα;
where from

where L is the center distance of the stand rollers;
R is the rolling radius of the test wheel with the tire (radius of the deformable wheel analog);
r radius of the stand roller.

 Comparative analysis with the prototype shows that the inventive method is characterized in that the system of the wheel stand the wheel is subjected to a special calibration operation performed using a non-deformable wheel analogue, which allows you to accurately determine the mechanical loss in the stand itself in accordance with specific test conditions. Comparison of the proposed solution not only with the prototype, but also with other technical solutions revealed in them signs that distinguish the claimed solution from the prototype, which allows us to conclude that the criterion of "significant differences".

 In FIG. 1 shows one of the possible options for implementing the method: 1 - a test wheel with a tire, 2 stand rollers, 3 lever for loading the system with torque, 4 lever sector, 5 dynamometer, 6 inextensible thread connecting the lever sector with a dynamometer.

 The method is implemented as follows.

First, a non-deformable analogue of the test wheel is installed on the roller stand. The radius of the analogue is taken equal to the radius R of the rolling wheel. The axis of the wheel (non-deformable analogue) is loaded with the vertical force G _H , gradually increasing its value from the minimum to the maximum allowable, and for each value of G _{H the} force P ₁ , which occurs when the system rolls the wheel stand, is determined. Determine the value of the moment of resistance of the system to scroll according to the formula
M _C P ₁ • R _p .

Thus, the dependence of the moment of resistance of the system on the vertical load is obtained when using an undeformable analogue as a wheel (the first stage of testing):
M _C1 = f (G _H ).

 In figure 2, this function is shown at number 1.

Then, instead of a non-deformable analogue, a test wheel with a tire is mounted on a stand. The tests are carried out according to the program described above and get the dependence of the resistance moment in the system on the vertical load in the presence of a wheel with a deformable tire (second stage of the test):
M _C2 f (G _H ).

 In figure 2, this function is shown at number 2.

Based on the first and second dependencies, the mechanical losses in the tire are determined as a function of the load resistance moment M _C3 G _H as the difference between the second and first functional dependence:
M _C3 = f (G _H ) M _C2 -M _C1 .

 In FIG. 2, this function is shown at number 3.

Literature
1. A.S. N 217673, G 01 M 17/02, 1968.

 2. Technical operation of cars. Ed. prof. G.V. Kramarenko. M. Transport, 1983.

Claims (2)

1. The bench method for determining mechanical losses in the tire, which consists in determining the mechanical losses in the system of the roller stand of the wheel by loading the system with a vertical load and fixing the moment of resistance of the system to the rotation corresponding to this load, characterized in that the test system of the roller stand of the wheel is carried out in two stages: the first stage determines the loss in the system of the roller stand wheel when using its non-deformable analogue as the wheel, fix the loss in the system in the form of and moment M _c1 scroll system resistance on vertical load G _n on the wheel (M _c1 f (G _n)), in the second step is performed system tests roller stand wheel using the same booth, in which instead of the non-deformable analog set test wheel with deformable bus , tests performed with the same program and determining a second relationship moment M _c2 scroll system resistance on vertical load G _n (M _c2 f (G _n)), determine the mechanical losses in the tire as a function of the resistance moment M _c3 eights Wheels with bus scrolling the vertical load G _n as the difference between the moments of resistance in the second and first stage system roller test stand wheel
M _c3 f (G _n ) M _s2 M _s1 . 2. The method according to claim 1, characterized in that the geometric parameters of the non-deformable analogue of the test wheel is selected taking into account the dependencies
P _c = f _to • G _n • cosα,
where P _{with the} strength of the rolling resistance of the wheel;
f _{to the} coefficient of rolling resistance;
G _n vertical load on the wheel;
α is the angle between the vertical and the straight line passing through the center of the wheel mounted on the roller stand, and the center of the stand roller;

where L is the center distance of the stand rollers;
r radius of the roller;
R is the radius of the non-deformable wheel analog equal to the rolling radius of the test wheel.

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