A test method and program product for the vibration resistance of a tire-rim assembly under free working conditions

Abstract

The present invention relates to the technical field of tire NVH testing, and more particularly to a method and program product for testing the vibration resistance of a tire-rim assembly under free operating conditions. The present invention provides a method for testing the vibration resistance of a tire-rim assembly under free operating conditions. The method employs two accelerometers arranged on the tread to obtain the tread frequency response through averaging. Accelerometers are arranged on either side of the rim center hole to obtain the rim center frequency response through averaging. Finally, radial force transmission is calculated to determine the vibration resistance of the tire-rim assembly. The method provides high test accuracy, stability, and reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of tire NVH testing, and in particular to a testing method and program product for the vibration resistance of a tire-rim assembly under free working conditions. Background Art

[0002] A tire's vibration resistance can be measured by the force transfer from the tread to the center of the rim. The amplitude of the force transfer curve reflects the tire's ability to resist vibration, typically measured by its peak value. A smaller peak value indicates greater energy absorption and improved vibration resistance. Therefore, the combined force transfer characteristics of the tire and rim can be used to measure the vibration resistance of the tire and the vehicle. Of the three directions, radial, lateral, and longitudinal, the radial direction has the greatest impact on vehicle vibration and is the most sensitive to it by passengers. Therefore, the radial force transfer characteristics of the tire and rim combination can be used to measure the tire's vibration resistance.

[0003] Prior art invention patents (Granted Publication Number: CN104344937 B, Granted Publication Date: 20171229) disclose a method for testing the vibration isolation performance of automotive wheels. However, only one accelerometer is installed on the tire tread, located at the top of the tread. Due to factors such as tire uniformity and the variety of rim spokes, the tire and rim combination is not uniform, resulting in variations in force transfer characteristics in different directions of the tread, particularly the peak value of the force transfer curve. Furthermore, with the increasing number of sound-absorbing cotton tires, the radial force transfer characteristics of different points on the tread of these tires may vary even more. Therefore, measuring only a single point is likely to result in significant deviations in the test results, necessitating further improvements in test accuracy and stability. Invention patents (Granted Publication Number: CN112033704 B, Granted Publication Date: 20180925) disclose a method for testing the vibration isolation performance of a wheel. This method requires separate measurement of the lateral stiffness of the tire-rim assembly and the rim, as well as weighing the tire and rim separately. This method involves relatively many testing steps and results in low test efficiency. Summary of the Invention

[0004] To address the aforementioned technical issues, the present invention provides a method for testing the vibration resistance of a tire-rim assembly under free working conditions. This method employs two accelerometers placed on the tread to obtain the tread frequency response through averaging. Accelerometers are placed on both sides of the rim center hole to obtain the rim center frequency response through averaging. Finally, radial force transmission is calculated, thereby obtaining more accurate and objective vibration resistance test results.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] A method for testing the vibration resistance of a tire-rim assembly under free working conditions, the method comprising the following steps:

[0007] 1) Install the tire on the vehicle rim and adjust it to the test pressure;

[0008] 2) Glue two triaxial accelerometers (numbered 2 and 3) through the base or gasket (using a magnetic base) on either side of the center hole of the rim.

[0009] 3) The tire is left to stand still indoors for more than 1 hour;

[0010] 4) suspending the tire-rim assembly on a rigid support with an elastic rope;

[0011] 5) An accelerometer is arranged above and below the tread. The one closest to accelerometer 2 is numbered 1, and the one closest to accelerometer 3 is numbered 4.

[0012] 6) Use a hammer to strike the inside of the center hole of the rim near accelerometer No. 3, pointing in the direction of accelerometer No. 4. Also strike the inside of the center hole of the rim near accelerometer No. 2, pointing in the direction of accelerometer No. 1. Automatically record the data.

[0013] 7) Data processing;

[0014] 7.1) Assume that when a strike is made near accelerometer 3, the frequency response functions of accelerometers 1, 2, 3, and 4 are H 13 、H 23 、H 33 、H 43 When a strike is made near accelerometer No. 2, the frequency response functions of accelerometers No. 1, 2, 3, and 4 are H 12 、H 22 、H 32 、H 42 , then the average frequency response function of the tread is FRF tread =(H 13 -H 43 –H 12 +H 42 ) / 4, the rim center frequency response function is FRF center =(H 23 +H 33 –H 22 -H 32 ) / 4, the average force transmission curve is FT=(H 13 -H 43 –H 12 +H 42 ) / (H 23 +H 33 –H 22 -H 32 );

[0015] 7.2) Assume that the first-order peak value and frequency of the force transfer curve FT are Peak1st 、Fre 1st , the cavity peak and frequency are Peak 2nd 、Fre 2nd , the FT curve Fre obtained by the test 1st and Fre 2nd The curves nearby are smooth, without obvious jitter, and Fre 1st and Fre 2nd The test error is ±1Hz, and at least 3 valid results are obtained.

[0016] 7.3) The vertical unit of the force transmission curve FT is dB. The Peak value of the three effective curves is selected. 1st The curve at the middle value, if Peak 1st If there are two or more of the same, then there are the same Peak 1st In the curve, select Peak 2nd The curve at the middle value;

[0017] 7.4) Tread Frequency Response Function (FRF) tread The vertical axis unit is g / N, (m / s 2 ) / N or dB.

[0018] Preferably, in step 1), the vehicle rim is preferably a rim that is actually used. Otherwise, a rim with similar material, spokes and eccentricity is selected.

[0019] Preferably, in step 2), the accelerometers are equidistant from the center of the rim and the connecting line passes through the center of the rim.

[0020] Preferably, in step 3), the indoor temperature is controlled between 25±5°C.

[0021] Preferably, in step 4), the tire-rim assembly satisfies a "free-free" boundary condition when suspended.

[0022] Preferably, in step 5), the accelerometers placed on the tread are unidirectional or tridirectional, and their bases or gaskets are glued to the upper and lower centers of the tread with glue. If the upper center or lower center of the tread happens to be a groove, the groove position is avoided. The four accelerometers are all located on the transverse center plane, and the rim valve stem avoids the transverse center plane.

[0023] Preferably, before testing, check whether the glue is completely dry, whether the accelerometer base or gasket is firmly attached, and whether the air pressure is accurate; the air pressure error is required to be within ±3kPa. If it exceeds this range, adjust to the test pressure and let it stand for more than 10 minutes, then retest the air pressure until the pressure meets the requirement.

[0024] Preferably, the test bandwidth is set to 1024 Hz, the resolution is set to 1 Hz or 0.5 Hz, the force signal is added with a force exponential window, the acceleration signal is added with an exponential window, and the average value of 6 taps is taken during the test.

[0025] Preferably, in step 7), within the set bandwidth, the extracted test results include the force transfer curve FT and its one-third octave curve, the first-order peak and frequency, the cavity peak and frequency, the RMS value of any frequency band, and the tread frequency response function FRF. tread Its one-third octave band curve, first-order peak and frequency, cavity peak and frequency, RMS value of any frequency band, FT and FRF tread The first-order peak, cavity peak and RMS value of the custom frequency band are used as the basis for evaluating the anti-vibration performance. The lower the value, the better the anti-vibration performance.

[0026] Furthermore, the present invention also discloses a method for testing the anti-vibration performance of a tire-rim assembly under free working conditions, and the method is applied in testing the anti-vibration performance of the tire-rim assembly.

[0027] Furthermore, the present invention also discloses a computer program product, including a computer program or instructions, which implements the data processing process in step 7) of the method when executed by a processor.

[0028] Due to the adoption of the above technical solution, the present invention can more accurately measure the radial anti-vibration performance of the tire-rim assembly, improve the test accuracy, and enhance the stability and reliability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the arrangement of accelerometers according to an embodiment of the present invention.

[0030] Figure 2 These are three valid test results of the 225 / 55R19 specification described in the embodiment of the present invention.

[0031] Figure 3 This is the 225 / 55R19 specification force transmission and its one-third octave band curve described in the embodiment of the present invention.

[0032] Figure 4 This is the 225 / 55R19 specification tread frequency response and its one-third octave band curve described in the embodiment of the present invention.

[0033] Figure 5 These are the results of three effective tests on the 235 / 45ZR18 sound-absorbing cotton tire described in the embodiment of the present invention.

[0034] Figure 6 This is the force transmission and one-third octave band curve of the 235 / 45ZR18 sound-absorbing cotton tire described in the embodiment of the present invention.

[0035] Figure 7 This is the tread frequency response and one-third octave band curve of the 235 / 45ZR18 sound-absorbing cotton tire described in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The method of the invention is used for testing the vibration resistance of tire-rim assemblies of various types of tires.

[0037] The present invention is further illustrated by an example below. This example is implemented based on the technical solution of the present invention, but the scope of protection of the present invention is not limited to the following example. This example tests two specifications: 225 / 55R19 ordinary tire and 23545ZR18 sound-absorbing cotton tire.

[0038] To test the anti-vibration performance of the tire-rim assembly, the transfer function can be tested first, and then the force transmission can be calculated through the transfer function to determine the strength of the anti-vibration performance of the tire-rim assembly.

[0039] The accelerometer layout is as follows: Figure 1 When struck near accelerometer 3, the frequency response functions of accelerometers 1, 2, 3, and 4 are H 13 、H 23 、H 33 、H 43 When a strike is made near accelerometer No. 2, the frequency response functions of accelerometers No. 1, 2, 3, and 4 are H 12 、H 22 、H 32 、H 42 , assuming the rim center number is 0, then the span frequency response of accelerometer No. 1 is:

[0040]

[0041] The crossover frequency response of accelerometer No. 4 is:

[0042]

[0043] From (1) and (2), the average cross-point frequency response of the tread is:

[0044]

[0045] The frequency response of the rim center origin is:

[0046]

[0047] Then, from (3) and (4), the average force transmission can be obtained as:

[0048]

[0049] A 225 / 55R19 tire was tested. The tire was mounted on a vehicle rim and inflated to a test pressure of 230 kPa. Two triaxial accelerometer mounts were glued to either side of the rim's center hole, with the line connecting the two accelerometers passing through the center of the rim and equidistant from the wheel center. After standing still indoors for one hour, the tire and rim assembly was suspended from a rigid support using elastic cords, creating a "free-free" boundary condition. A uniaxial accelerometer was placed at the center of the tread, above and below the tread. All four accelerometers were located in the transverse center plane, with the rim valve facing away from the transverse center plane. The computer, front end, hammer, and accelerometers were connected, and the front end and computer were turned on. Inspection confirmed that the glue had dried thoroughly and the accelerometer mounts were securely attached. The room temperature was 27.0°C, and the tire pressure was 232 kPa, meeting the test requirements. Open the test software, set the channel range, tap the inside of the rim center hole with a hammer, obtain the trigger parameters, set the bandwidth to 1024Hz, the resolution to 1Hz, the force signal with a force exponential window, the acceleration signal with an exponential window, set 6 averages, the amplitude is in RMS format, the test number automatically increases, the FRF estimate is Hv, automatically reject overload, monitor double clicks, and automatically reject double clicks. After checking that all settings are correct, conduct the test. Take the frequency range as 25-300Hz, and the frequency range of the RMS value as between 25-300Hz. The force transfer and tread frequency response obtained by accelerometer No. 1 are expressed as up, the force transfer and tread frequency response obtained by accelerometer No. 4 are expressed as down, and the average force transfer and tread frequency response are expressed as average, the same below. The force transfer curve and tread frequency response curve of the three valid test results are as follows. Figure 2 shown.

[0050] Depend on Figure 2 It can be seen that the Peak of FT above and below the tread 1st Peak 2nd There are some differences, but the differences are small. The first-order peak value of the tread frequency response is also small. The first-order peak value of the average force transfer curve FT of the three tests is 1st The results of the first test are 21.11, 21.07 and 21.18 respectively. The results of the first test are in the middle, so the first test is selected as the final result. The force transmission FT and its one-third octave band curve of the test results are shown in Figure 2. Figure 3 As shown, the tread frequency response and its one-third octave band curve are as follows Figure 4 shown.

[0051] The sound-absorbing cotton tire with the specification of 235 / 45ZR18 was tested with the test pressure of 230kPa and the indoor temperature of 27.5℃. The results of three tests are as follows: Figure 5 shown.

[0052] Depend on Figure 5 It can be seen that the Peak of FT above and below the tread 1st Peak2nd The difference is obvious, and the difference in the first-order peak value of the tread frequency response is also quite obvious. 1st The results of the third test are 20.91, 20.83 and 20.67 respectively. The third test result is in the middle, so the third test is selected as the final result. The force transmission and one-third octave band curves of the test results are shown in Figure 2. Figure 6 As shown, the tread frequency response and its one-third octave band curve are as follows Figure 7 shown.

[0053] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for testing the vibration resistance of a tire-rim assembly under free working conditions, characterized in that: The method comprises the following steps: 1) Install the tire on the vehicle rim and adjust it to the test pressure; 2) Glue two triaxial accelerometers on either side of the rim center hole through the base or spacer. Label them accelerometer 2 and accelerometer 3. 3) The tire is left to stand still indoors for more than 1 hour; 4) Hang the tire-rim assembly on a rigid support with an elastic rope; 5) An accelerometer is arranged above and below the tread. The one closest to accelerometer 2 is numbered 1, and the one closest to accelerometer 3 is numbered 4. 6) Use a hammer to strike the inside of the center hole of the rim near accelerometer No. 3, pointing toward accelerometer No.

4. Also strike the inside of the center hole of the rim near accelerometer No. 2, pointing toward accelerometer No.

1. Automatically record the data. 7) Data processing; 7.1) Assume that when a strike is made near accelerometer 3, the frequency response functions of accelerometers 1, 2, 3, and 4 are H and 13 、H 23 、H 33 、H 43 When a strike is made near accelerometer No. 2, the frequency response functions of accelerometers No. 1, 2, 3, and 4 are H 12 、H 22 、H 32 、H 42 , then the average frequency response function of the tread is FRF tread =(H 13 -H 43 – H 12 + H 42 ) / 4, the rim center frequency response function is FRF center = (H 23 + H 33 – H 22 -H 32 ) / 4, the average force transmission curve is FT = (H 13 -H 43 – H 12 + H 42 ) / (H 23 +H 33 – H 22 -H 32 ); 7.2) Assume that the first-order peak value and frequency of the force transfer curve FT are Peak 1st 、Fre 1st , the cavity peak and frequency are Peak 2nd 、Fre 2nd , the FT curve Fre obtained by the test 1st and Fre 2nd The curves nearby are smooth, without obvious jitter, and Fre 1st and Fre 2nd The test error is ±1Hz, and at least 3 valid results are obtained. 7.3) The vertical unit of the force transmission curve FT is dB. The Peak value of the three effective curves is selected. 1st The curve at the middle value, if Peak 1st If there are two or more of the same, then there are the same Peak 1st In the curve, select Peak 2nd The curve at the middle value; 7.4) Tread Frequency Response Function (FRF) tread The vertical axis unit is g / N, (m / s 2 ) / N or dB.

2. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: When using car rims, try to use rims that are actually in use. Otherwise, choose rims with similar materials, spokes, and eccentricity.

3. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: In step 2), use the magnetic base to attach the three-axis accelerometer.

4. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: In step 2), accelerometers 2 and 3 are equidistant from the center of the wheel rim and the connecting line passes through the center of the wheel rim.

5. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: In step 3), the indoor temperature is controlled between 25±5℃.

6. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: In step 4), the tire-rim assembly satisfies the "free-free" boundary condition when suspended.

7. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: In step 5), the accelerometers placed on the tread are unidirectional or tridirectional, and their bases or gaskets are glued to the upper and lower centers of the tread with glue. If the upper or lower center of the tread happens to be a groove, the groove position is avoided. All four accelerometers are located on the transverse center plane, and the rim valve stem avoids the transverse center plane.

8. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: Before testing, check whether the glue is completely dry, whether the accelerometer base or gasket is firmly attached, and whether the air pressure is accurate. The air pressure error is required to be within ±3kPa. If it exceeds this range, adjust it to the test pressure and let it stand for more than 10 minutes, then retest the air pressure until the pressure meets the requirement.

9. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: The test bandwidth is set to 1024 Hz, the resolution is set to 1 Hz or 0.5 Hz, the force signal is added with a force exponential window, the acceleration signal is added with an exponential window, and the average value of 6 taps is taken during the test.

10. The method for testing the vibration resistance of a tire-rim assembly under free working conditions according to claim 1, characterized in that: In step 7), within the set bandwidth, the extracted test results include the force transfer curve FT and its one-third octave band curve, the first-order peak and frequency, the cavity peak and frequency, the RMS value of any frequency band, and the tread frequency response function FRF. tread Its one-third octave band curve, first-order peak and frequency, cavity peak and frequency, RMS value of any frequency band, FT and FRF tread The first-order peak, cavity peak and RMS value of the custom frequency band are used as the basis for evaluating the anti-vibration performance. The lower the value, the better the anti-vibration performance.

11. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the data processing process in step 7) of the method according to any one of claims 1 to 10 is implemented.

Images