Test method for dynamic impact test of tires

Abstract

The present invention provides a test method for dynamic impact test of tires, comprising the following steps: Test preparation: Install the tire-rim assembly on the test equipment, which includes a load wheel with exciters provided on its surface, apply a load to the tire and make it contact with the surface of the load wheel; t times of impact tests: Take t test points at equal intervals along the circumferential surface of the tire, the t test points divide the circumference of the tire into equal t parts, the load wheel drives the tire to rotate and makes each test point on the tire pass through the exciter at the test speed respectively, and record the fluctuations of the forces in each direction of the tire during the process of each test point passing through the exciter; where t is the common divisor of 2 and 3 or the common divisor of 2, 3 and 4; Take the average value of the results of the t times of impact tests for subsequent analysis. This test method can reduce or even eliminate the influence of tire non-uniformity on the test results and improve the accuracy of the dynamic impact test.

Description

Technical Field

[0001] The present invention belongs to the technical field of tire detection, and particularly relates to a test method for a tire dynamic impact test. Background Art

[0002] With the continuous development of the economic society, people have put forward higher requirements for the riding comfort of vehicles. As the only component of a vehicle in contact with the ground, a tire plays a very crucial role in absorbing and buffering the excitation of road surface unevenness. Indoor tests usually use a tire dynamic impact test (cleat test) to simulate the process of a tire passing over an obstacle, obtain the magnitude and attenuation change of its axial force, and then analyze its dynamic behavior characteristics, which is an important means for evaluating, predicting, and improving comfort.

[0003] A tire is a product composed of multiple materials through multiple complex processes, and there are inevitably non-uniformities in quality, shape, and stiffness, which are manifested as non-uniform axial forces during testing and tire use. The non-uniformity of a tire mainly comes from process variations, and different tires with the same tire design may exhibit completely different non-uniformities. The non-uniformity of a tire will seriously affect the feedback results of the axial force in a tire dynamic impact test, reduce the test accuracy, and interfere with the comparison of the axial force magnitude and attenuation of different tire design schemes.

[0004] How to eliminate the influence of tire non-uniformity is the key to improving the accuracy of tire dynamic impact testing and ensuring data reliability. Currently, the commonly used method is to screen the tires for dynamic impact through low-speed uniformity testing, and select the tires with smaller radial first harmonic values of low-speed uniformity for dynamic impact testing to minimize the influence of non-uniformity to the greatest extent.

[0005] The method of screening tires by low-speed uniformity testing and then testing dynamic impact has the following main disadvantages: (1) It can only reduce errors to a certain extent and cannot completely eliminate the influence of non-uniformity, with low efficiency in improving accuracy; (2) There are differences between high-speed and low-speed uniformity, which may cause screening failure. The drum speed of low-speed uniformity testing is fixed, and the converted linear speed is generally 6 - 10 km / h, with a relatively low speed; the dynamic impact test is to simulate the actual driving condition, with a speed generally of 40 - 60 km / h, which is relatively high. High-speed uniformity and low-speed uniformity often have large differences and there is no clear rule or correlation, so the effectiveness of screening with low-speed uniformity is poor. Summary of the Invention

[0006] In view of at least one deficiency existing in the prior art, the present invention provides a test method for a tire dynamic impact test, which can reduce or even eliminate the influence of tire non-uniformity on test results and improve the accuracy of dynamic impact testing.

[0007] An embodiment of the present invention provides a test method for a tire dynamic impact test, including the following steps:

[0008] Test preparation: Install the tire-rim assembly on the test equipment. The test equipment includes a load wheel, and an exciter is provided on the surface of the load wheel. Load the tire with a load and make it contact the surface of the load wheel.

[0009] t - time impact test: Take t test points at equal intervals along the circumferential surface of the tire. The t test points divide the circumference of the tire into t equal parts. The load wheel drives the tire to rotate and makes each test point on the tire pass through the exciter at the test speed, and record the fluctuations of the forces in each direction of the tire during the process of each test point passing through the exciter. Wherein, t is the common divisor of 2 and 3 or the common divisor of 2, 3, and 4.

[0010] Take the average value of the results of the t - time impact test for subsequent analysis.

[0011] In some embodiments of the present invention, the t - time impact test specifically includes the following steps:

[0012] Determine the impact test angle: y = (C ir / t - C ir *x)*360° / C ir where: L / C ir = m + x, L is the circumference of the load wheel, C ir is the rolling circumference of the tire, m is an integer, and x is the remainder.

[0013] One - time impact test: The load wheel is loaded to the test speed and drives the tire - rim assembly to rotate. As the load wheel rotates, the exciter on the surface of the load wheel contacts and passes through the tire surface, and then the tire disengages from the load wheel and the load wheel stops rotating. Record the fluctuations of the forces in each direction of the tire from the time when the tire contacts the exciter to the time when it disengages from the load wheel.

[0014] Two - time impact test: At the beginning of the test, both the load wheel and the tire are at the position where they disengaged from each other in the previous impact test. Rotate the tire by an angle y, then reload the load and make it contact the load wheel again. The load wheel drives the tire to rotate again and reloads to the test speed, repeat the impact test process, and record the fluctuations of the forces in each direction of the tire from the time when the tire contacts the exciter to the time when it disengages from the surface of the load wheel.

[0015] Repeat the above impact test process. Rotate the tire by an angle y before each test until the t - time impact test is completed and the data of the t - time impact test are obtained.

[0016] In some embodiments of the present invention, when x = 0, the tire rotation angle y = 360° / t before each impact test; when 0 < x < 1 / t, y is a positive number, and the tire rotates counterclockwise by an angle y before each impact test; when x = 1 / t, y is 0°, and there is no need to rotate the tire before each impact test; when x > 1 / t, y is a negative number, and the tire rotates clockwise by an angle y before each impact test.

[0017] In some embodiments of the present invention, during each impact test, when the angle between the position where the actuator rotates to after passing through the tire surface and the contact position between the tire and the load wheel surface is θ, the tire disengages from the load wheel. Subsequently, the load wheel stops rotating. Before the next impact test when contacting the tire, the load wheel rotates back to the position where the angle between the actuator and the contact position is θ.

[0018] In some embodiments of the present invention, the length of θ*R can meet the requirements of dynamic impact data acquisition, and the length of (2π - θ)*R can meet the requirements of loading the tire to the test speed, where R is the radius of the load wheel.

[0019] In some embodiments of the present invention, θ = π is taken, that is, during each impact test, when the actuator rotates to directly below the load wheel, the tire disengages from the load wheel, and before the next impact test when contacting the tire, the load wheel rotates to make the actuator located directly below the load wheel.

[0020] In some embodiments of the present invention, the test air pressure of the tire is 200 - 250 kPa, and the test load is 50% - 80% of the maximum load of the tire.

[0021] In some embodiments of the present invention, the actuator is a bump provided on the surface of the load wheel, and the bump is arranged perpendicular to the traveling direction of the tire.

[0022] In some embodiments of the present invention, a force sensor is installed at the center of the load wheel, which can sense and record the changes in the radial, lateral, and longitudinal forces of the tire in real time.

[0023] In some embodiments of the present invention, t takes a value of 6 or 12.

[0024] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0025] (1) The test method for the tire dynamic impact test provided by the embodiments of the present invention cleverly eliminates the influence of the first three or the first four harmonics caused by the tire non-uniformity, significantly improves the accuracy of the dynamic impact test, is more suitable for the comparison between different design schemes, can strip the influence of the fluctuations caused by the process variation of the tire, and makes the test results more accurate and reliable.

[0026] (2) The test method of the tire dynamic impact test provided by the embodiments of the present invention has no requirements for the uniformity of the test tire. It is not necessary to perform low-speed uniformity screening on the tire before the test, and the uneven influence at the dynamic impact test speed is peeled off. The peeling effect on uniformity is much better than that of the prior art using low-speed uniformity screening.

[0027] (3) The test method of the tire dynamic impact test provided by the embodiments of the present invention has clear calculation formulas and test steps, can formulate a fixed test procedure for different tires, does not require too much human participation, is simple and convenient, and has good test effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention, form a part of this application, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is a schematic diagram of the dynamic impact test in the embodiments of the present invention Figure 1 ;

[0030] Figure 2 is a schematic diagram of the dynamic impact test in the embodiments of the present invention Figure 2 ;

[0031] Figure 3 is a schematic diagram of the distribution of each test point in the circumferential direction of the tire in one embodiment of the present invention;

[0032] Figure 4 is a schematic diagram of eliminating the influence of the first harmonic of non-uniformity in the embodiments of the present invention;

[0033] Figure 5 is a schematic diagram of eliminating the influence of the second harmonic of non-uniformity in the embodiments of the present invention;

[0034] Figure 6 is a schematic diagram of eliminating the influence of the third harmonic of non-uniformity in the embodiments of the present invention;

[0035] Figure 7 is a schematic diagram of the test results of Comparative Example 1;

[0036] Figure 8 is a schematic diagram of the test results of Comparative Example 2;

[0037] Figure 9 is a schematic diagram of the test results of Embodiment 1 of the present invention.

[0038] In the figure:

[0039] 1. Tire; 2. Load wheel; 3. Exciter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0041] Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0042] Referring to "embodiments" in the present application means that the specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those of ordinary skill in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments without conflict.

[0043] The schematic diagram of the tire dynamic impact test is as Figure 1 shown. During the test, the tire 1 to be tested is installed on the test rim and filled with the test air pressure. The tire-rim assembly is installed on the test equipment. The test equipment includes a load wheel 2, and an exciter 3 is provided on the surface of the load wheel 2. After applying the test load to the tire 1, the position of the rim center is fixed. The tire 1 is in contact with the load wheel 2, the distance between the rim center and the center of the load wheel 2 is fixed, the load wheel 2 rotates and drives the tire 1 to rotate, the directions of the angular velocities of the tire 1 and the load wheel 2 are opposite, and a force sensor is installed at the center of the load wheel 2, which can sense the changes in the radial, lateral and longitudinal forces of the tire in real time and record them.

[0044] Since a tire is a product formed by complex processes of multiple materials through multiple processes, it inevitably has non-uniformity, and the non-uniformity data of each tire are not completely the same. Taking the radial force fluctuation as an example, if the time is taken as the abscissa and the fluctuation of the tire radial force is taken as the ordinate, the fluctuation of the radial force of the tire rolling one week (i.e., one cycle) is a complex periodic function, which can be transformed into a combination of sine functions with different phases and different amplitudes through Fourier transform.

[0045] For a sine function, it can be proven that when the phase difference a is constant and the period T is divisible by a, the sum of T / a sine functions with a phase difference of a in sequence is 0. That is, it can be proven that:

[0046] If n is an integer greater than or equal to 1, then 2n is an even number;

[0047] From 2π / a = 2n, we get n*a = π;

[0048] sin(x + a) + sin(x + 2a) + sin(x + 3a) +...... + sin(x + (n + 1)*a) + sin(x + (n + 2)*a) +...... + sin(x + 2n*a) = [sin(x + a) + sin(x + (n + 1)*a)] + [sin(x + 2a) + sin(x + (n + 2)*a)] +...... + [sin(x + n*a) + sin(x + 2n*a)] = [sin(x + a) + sin(x + a + π)] + [sin(x + 2a) + sin(x + 2a + π)] +...... + [sin(x + n*a) + sin(x + n*a + π)]

[0049] From sin(x) + sin(x + π) = 0, the above equation becomes n*0 = 0.

[0050] When 2n - 1 is an odd number, it can also be proven that:

[0051] sin(x + a) + sin(x + 2a) + sin(x + 3a) +...... + sin(x + n*a) + sin(x + (n + 1)*a) +...... + sin(x + (2n - 2)*a) + sin(x + (2n - 1)*a) = 0

[0052] The present invention utilizes the above principle and adopts a form with the same phase difference at intervals and the phase difference being divisible by the period to reduce or even eliminate the influence of the inherent non-uniformity of the tire on the results of the dynamic impact test.

[0053] The test method for the tire dynamic impact test provided by the embodiment of the present invention includes the following steps:

[0054] Test preparation: Install the tire - rim assembly on the test equipment. The test equipment includes a load wheel, and excitation objects are arranged on the surface of the load wheel. Load is applied to the tire and it is in contact with the surface of the load wheel;

[0055] t - impact test: Take t test points at equal intervals along the circumferential surface of the tire. The t test points divide the circumference of the tire into t equal parts. The load wheel drives the tire to rotate and makes each test point on the tire pass through the exciter at the test speed, and record the fluctuations of the forces in each direction of the tire during the process of each test point passing through the exciter; where t is the common divisor of 2 and 3 or the common divisor of 2, 3, and 4;

[0056] Take the average value of the results of the t - impact test for subsequent analysis.

[0057] The test method of the tire dynamic impact test provided by the embodiment of the present invention, by using the mathematical fact that when the phase difference a is constant and the period T can be divided by the phase difference a, the sum of T / a sine functions with a phase difference of a in sequence is equal to 0, comprehensively considering the influence of each harmonic after the Fourier decomposition of the forces in each direction of the tire, equally divide one week of the tire into t parts at equal intervals, and t is the common divisor of 2 and 3 or the common divisor of 2, 3, and 4, so as to cleverly eliminate the influence of the first three or the first four harmonics caused by the tire non - uniformity. Thus, it is not necessary to perform low - speed uniformity screening on the tire before the test, significantly improving the accuracy of the dynamic impact test. For the comparison between different design schemes, the influence of the fluctuations caused by the process variation of the tire can be stripped, making the test results more accurate and reliable.

[0058] In the above embodiment, assuming that the period of the tire rotating one week is T, when taking t as the common divisor of 2 and 3, for example, when the t value is taken as 6, the schematic diagram of the distribution of each test point on the tire circumference is as Figure 3 shown, then:

[0059] For the first harmonic, the period is T, the amplitude is A, the phase difference is T / t, T / (T / t)=t = 6, the period T can be divided by the phase difference, and the influence of the first harmonic can be completely eliminated. See Figure 4 ;

[0060] For the second harmonic, the period is T / 2, the amplitude is B, the phase difference is T / t, (T / 2) / (T / t)=t / 2 = 3, the period T / 2 can be divided by the phase difference, and the influence of the second harmonic can be completely eliminated. See Figure 5 ;

[0061] For the third harmonic, the period is T / 3, the amplitude is C, the phase difference is T / t, (T / 3) / (T / t)=t / 3 = 2, the period T / 3 can be divided by the phase difference, and the influence of the third harmonic can be completely eliminated. See Figure 6 .

[0062] Since the influence of the first harmonic of the high-speed uniformity of the tire is the greatest at 40 - 60 km / h, and the first three harmonics account for more than 90% of the influence of non-uniformity, and the fourth harmonic can be basically ignored, therefore, according to the test method provided by the above embodiments of the present application, the influence of the first three harmonics of the tire non-uniformity can be almost completely stripped (taking the radial force fluctuation as an example, the longitudinal force and lateral force fluctuations are not shown, but the same applies and will not be elaborated), greatly improving the accuracy of the dynamic impact test.

[0063] To further improve the test accuracy, in some other embodiments, take t as the common divisor of 2, 3, and 4. For example, take t as 12. According to the above principle, use the above test method to conduct 12 impact tests respectively, and take the average value of the test results to shield the influence of the first four harmonics. However, since the value of the fourth harmonic is often not significant at a speed of 40 - 60 km / h, therefore, the fourth harmonic generally does not have a great impact on the test results. Considering that adding 6 test points requires 6 more tests, in practical applications, it is necessary to comprehensively consider the cost and test accuracy to select whether to adopt this scheme.

[0064] In the test preparation step, the distance between the initial contact position of the tire and the load wheel and the exciter is d, and d≠0; it can be understood that the value of d should be such that the rotational speed of the tire has reached the test speed before the exciter contacts the tire.

[0065] In some embodiments, the t - time impact test specifically includes the following steps:

[0066] Determine the impact test angle: y = (C ir / t - C ir *x)*360° / C ir where: L / C ir = m + x, L is the circumference of the load wheel, C ir is the rolling circumference of the tire, m is an integer, and x is the remainder;

[0067] One - time impact test: The load wheel is loaded to the test speed and drives the tire - rim assembly to rotate. As the load wheel rotates, the exciter on the surface of the load wheel contacts the tire and passes through the tire surface, and then the tire disengages from the load wheel and the load wheel stops rotating. Record the force fluctuations in all directions of the tire during the period from when the tire contacts the exciter to when it disengages from the load wheel.

[0068] Two - time impact test: At the beginning of the test, both the load wheel and the tire are located at the position where they disengaged from each other in the previous impact test. Rotate the tire by an angle y and then re - load the load and contact the load wheel. The load wheel drives the tire to rotate again and re - load it to the test speed, repeat the impact test process, and record the force fluctuations in all directions of the tire during the period from when the tire contacts the exciter to when it disengages from the surface of the load wheel.

[0069] Repeat the above impact test process. Before each test, rotate the tire by an angle y until t impact tests are completed and data from t impact tests are obtained.

[0070] In the above embodiments, when x = 0, that is, when the circumference L of the load wheel is exactly an integer multiple of the rolling circumference C of the tire ir each time before the impact test, the tire rotation angle y = 360° / t; that is to say, after the load wheel rotates one week, the tire rotates back to the position where it initially contacts the load wheel. At this time, the set impact test included angle of the tire rotation can be used to test the next test point;

[0071] When x ≠ 0, that is, the circumference L of the load wheel is not an integer multiple of the rolling circumference C of the tire ir According to the relationship formula L / C ir = m + x, we get L = C ir *m + C ir *x. After each rotation of the load wheel by one week, the arc length between the point where the tire contacts the load wheel and the initial contact position differs by C ir *x. It is necessary to rotate the tire back to the initial contact position and then rotate the tire to the next test point. Therefore, the impact test included angle y = (C ir / t - C ir *x)*360° / C ir .

[0072] Specifically, when 0 < x < 1 / t, y is a positive number, and the tire rotates counterclockwise by an angle y before each impact test; when x = 1 / t, y is 0°, and at this time, the next test point can be reached through the difference between the load wheel and the integer multiple of the tire circumference, and the tire does not need to be rotated before each impact test; when x > 1 / t, y is a negative number, and the tire rotates clockwise by an angle y before each impact test.

[0073] During the impact test, the load wheel drives the tire to rotate. When the tire separates from the load wheel, both will continue to rotate by a certain angle under the action of inertia and then stop without external interference. In the above embodiments, the relationship between the load wheel circumference and the tire circumference is used to determine the position of the test point for each impact test on the tire. Therefore, it is necessary to ensure that before each test, the load wheel and the tire return to the position where they separated during the previous impact test, so as to avoid the influence of the rotation during the deceleration stop process on the determination of the test point, so that the test point for the next impact test can be determined according to the above impact test included angle formula. For example, after the tire and the load wheel stop rotating and at the beginning of the next test, the tire and the load wheel can be rotated back to the position where they separated last time respectively.

[0074] In some embodiments, the tire can be locked immediately when it separates from the load wheel so that it no longer rotates, so that it is not necessary to adjust the position of the tire again before the next test.

[0075] In some embodiments, as Figure 2 shown, during each impact test, when the angle between the position where the actuator rotates to after passing through the tire surface and the contact position between the tire and the load wheel surface is θ, the tire disengages from the load wheel, and then the load wheel stops rotating. Before contacting the tire in the next impact test, the load wheel rotates back to the position where the angle between the actuator and the contact position is θ. For example, during one impact test, the tire disengages from the load wheel when the actuator rotates to an angle θ of π / 2 or π. Subsequently, the load wheel stops rotating. During the process from when the load wheel starts braking until it completely stops, it may have rotated a certain angle. The load wheel needs to be rotated back to θ being π / 2 or π before the second impact test is carried out to ensure that the above impact test angle y is always applicable.

[0076] In some embodiments, the length of θ*R can meet the requirements for collecting dynamic impact data, and the length of (2π - θ)*R can meet the requirement for loading the tire to the test speed, where R is the radius of the load wheel. Thus, the end position of each impact test neither affects the collection of dynamic impact data in this impact test nor enables the speed of the tire to reach the test speed before the actuator contacts the tire during the next impact test.

[0077] In some embodiments, θ = π is taken, that is, during each impact test, when the actuator rotates to directly below the load wheel, the tire disengages from the load wheel, and at the same time, the load wheel stops rotating. Before contacting the tire in the next impact test, the load wheel rotates to make the actuator located directly below the load wheel. Setting the start and end points of each impact test to the position where the actuator is directly below the load wheel makes the control of the test process more visual and convenient for the operation and management of the test process.

[0078] Since the possibility that the circumference of the load wheel is an integer multiple of the rolling circumference of the tire is very small, the position of the tire passing through the actuator is different each time, and there is a certain distance between the test points where the tire passes through the actuator twice. As long as the number of tests is large enough and the test points where the tire contacts the actuator around one week are sufficiently dispersed, and each test point is close to evenly dividing the tire circumference, the influence of tire non-uniformity can also be reduced to a certain extent. Therefore, in some other embodiments, it can be adopted that the tire does not disengage from the load wheel after passing through the actuator each time, the load wheel rotates continuously, the tire passes through the actuator multiple times and the data of forces in each direction are collected, thereby simplifying the test process and facilitating the operation. Thus, it should be noted that the statement in this application "t test points are taken at equal intervals along the circumferential surface of the tire, and the t test points divide the circumference of the tire into equal t parts" includes the above nearly equal situations.

[0079] In some embodiments, the test air pressure of the tire is the actual vehicle air pressure or is set according to actual needs, and the test air pressure is generally 200 - 250 kPa. The test load is the actual vehicle load or is set according to actual requirements, and the test load is generally 50% - 80% of the maximum load of the tire. The test rim selects high-precision tires and uses standard rim sizes.

[0080] In some embodiments, the exciter is a bump provided on the surface of the load wheel. The bump is arranged perpendicular to the traveling direction of the tire, and the size of the bump is designed according to actual needs. For example, it can be 15 mm * 15 mm. In the art, this bump is also called a cleat block.

[0081] In some embodiments, a force sensor is installed at the center of the load wheel, which can sense the changes in the radial, lateral, and longitudinal forces of the tire in real time and record them.

[0082] Test result verification

[0083] The test tire specification is 215 / 55R17. The test conditions are an actual vehicle load of 4100 N, an inflation pressure of 230 Kpa, a test speed of 60 km / h, the cleat block size is 15 * 15 mm, and the cleat block is perpendicular to the traveling direction of the tire.

[0084] Tires are selected for testing from the tire samples of the same design scheme. The selected tire information is shown in Table 1. Since the dynamic impact test and the high-speed uniformity test both take the radial force fluctuation as the main observed data, only the data related to the radial force fluctuation are listed in Table 1 for illustration. However, it can be understood that the longitudinal force and lateral force fluctuations are also applicable.

[0085] Table 1 Test tire uniformity data

[0086]

[0087] Comparative example 1

[0088] Tire A with a relatively large radial force fluctuation is selected, and an existing dynamic impact test method is used to conduct a dynamic impact test once, simulating the situation in the prior art where the low-speed uniformity of the tire is not detected before the test. The test results are as Figure 7 shown. After the tire leaves the cleat block, the attenuation of the axial force is irregular and the abnormal fluctuation is very large. It can be seen that the test results are greatly affected by the poor uniformity of the tire.

[0089] Comparative example 2

[0090] Tire B with a relatively small radial force fluctuation is selected, and an existing dynamic impact test method is used to conduct a dynamic impact test once, simulating the situation in the prior art where the low-speed uniformity of the tire is detected before the test and a tire with better uniformity is selected for the test. The test results are as Figure 8As shown, the attenuation of the axial force after the tire leaves the cleat block is still irregular. Compared with Figure 7 that, the abnormal fluctuation decreases, but the degree of decrease is limited. The test results are still affected by the poor tire uniformity.

[0091] Example 1

[0092] Select tire A with a large radial force fluctuation, and use the test method of the tire dynamic impact test provided by the embodiment of the present invention. Conduct 6 impact tests and take the average of the 6 test results to obtain Figure 9 the results shown. As Figure 9 shown, the attenuation of the axial force after the tire leaves the cleat block gradually decreases. Compared with Figure 7 and Figure 8 the results of, the abnormal fluctuation disappears significantly, perfectly stripping the influence of poor uniformity. The test results can better reflect the attenuation of the force after the dynamic impact of the tire of this design scheme, greatly improving the accuracy of the dynamic impact test. In particular, it can more effectively compare two design schemes, and is more accurate and reliable.

[0093] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same and similar parts among the various embodiments can be referred to each other.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: still modifications can be made to the specific implementation manners of the present invention or equivalent replacements can be made to some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A test method for tire dynamic impact test, characterized in that, it includes the following steps: Test preparation: Install the tire-rim assembly on the test equipment. The test equipment includes a load wheel, and there are excitants on the surface of the load wheel. Load the tire with a load and make it contact with the surface of the load wheel; t times of impact tests: Take t test points at equal intervals along the circumferential surface of the tire. The t test points divide the circumference of the tire into equal t parts. The load wheel drives the tire to rotate and makes each test point on the tire pass through the excitants at the test speed respectively, and record the fluctuations of the forces in each direction of the tire during the process of each test point passing through the excitants; where t is the common divisor of 2 and 3 or the common divisor of 2, 3 and 4; Take the average value of the results of the t times of impact tests for subsequent analysis; The specific steps of the t times of impact tests include the following: Determine the included angle of the impact test: y = (C ir / t - C ir * x) * 360° / C ir , where: L / C ir = m + x, L is the circumference of the load wheel, C ir is the rolling circumference of the tire, m is an integer, and x is the remainder; One-time impact test: The load wheel is loaded to the test speed and drives the tire-rim assembly to rotate. As the load wheel rotates, the excitants on the surface of the load wheel contact the tire and pass through the tire surface, and then the tire disengages from the load wheel and the load wheel stops rotating. Record the fluctuations of the forces in each direction of the tire from the time when the tire contacts the excitants to the time when it disengages from the load wheel; Two-time impact test: At the beginning of the test, both the load wheel and the tire are at the position where they disengaged from each other in the previous impact test. Rotate the tire by an angle y and then reload the load and make it contact with the load wheel. The load wheel drives the tire to rotate again and reloads to the test speed, repeat the impact test process, and record the fluctuations of the forces in each direction of the tire from the time when the tire contacts the excitants to the time when it disengages from the surface of the load wheel; Repeat the above impact test process, rotate the tire by an angle y before each test until the t times of impact tests are completed and the data of the t times of impact tests are obtained.

2. The test method for tire dynamic impact test according to claim 1, characterized in that: When x = 0, the rotation angle y of the tire before each impact test is 360° / t; When 0 < x < 1 / t, y is a positive number, and the tire rotates counterclockwise by an angle y before each impact test; When x = 1 / t, y is 0°, and there is no need to rotate the tire before each impact test; When x > 1 / t, y is a negative number, and the tire rotates clockwise by an angle y before each impact test.

3. The test method for tire dynamic impact test according to claim 1 or 2, characterized in that, During each impact test, when the angle between the excitants and the contact position between the tire and the surface of the load wheel after passing through the tire surface is θ, the tire disengages from the load wheel, and then the load wheel stops rotating. Before the next impact test and contacting the tire, the load wheel rotates back to the position where the angle between the excitants and the contact position is θ.

4. The test method for tire dynamic impact test according to claim 3, characterized in that, The length of θ*R can meet the requirements of dynamic impact data acquisition, and the length of (2π - θ)*R can meet the requirements of loading the tire to the test speed, where R is the radius of the load wheel.

5. The test method for tire dynamic impact test according to claim 4, characterized in that, Take θ = π, that is, during each impact test, when the exciter rotates to directly below the load wheel, the tire disengages from the load wheel, and before contacting the tire in the next impact test, the load wheel rotates to position the exciter directly below the load wheel.

6. The test method for the dynamic impact test of a tire according to claim 1, characterized in that, the test air pressure of the tire is 200 - 250 kPa, and the test load is 50% - 80% of the maximum load of the tire.

7. The test method for the dynamic impact test of a tire according to claim 1, characterized in that, the exciter is a convex block provided on the surface of the load wheel, and the convex block is arranged perpendicular to the traveling direction of the tire.

8. The test method for the dynamic impact test of a tire according to claim 1, characterized in that, a force sensor is installed at the center of the load wheel, which can sense the changes in the radial, lateral, and longitudinal forces of the tire in real time and record them.

9. The test method for the dynamic impact test of a tire according to claim 1, characterized in that, t takes a value of 6 or 12.

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