Method for evaluating tire vibration characteristics

Abstract

To provide a vibration characteristic evaluation method for a tire, which can accurately evaluate vibration characteristics of the tire.SOLUTION: This vibration characteristic evaluation method for the tire comprises: a preparation step S1 of preparing a tire 1 and a drum tester 2; a traveling step S2 of fitting the tire 1 to the drum tester 2 to travel; a measurement step S3 of measuring time-sequential data Y(t) of axial force 2 applied during riding of the tire 1 over a step 5; and an evaluation step S4 of evaluating vibration characteristics of the tire 1. The evaluation step S4 includes a first step S41 of frequency-analyzing the time-sequential data Y(t) of the axial force Y to calculate a unique angular frequency ω and an attenuation ratio ζ, a second step S42 of calculating vibration transmission characteristics H(t) of the tire 1, a third step S43 of inverse-convoluting the time-sequential data Y(t) of the axial force Y(t) to calculate time-sequential data X(t) of a force X applied on the tire 1; and a fourth step S44 of evaluating the vibration characteristics of the tire 1 on the basis of the time-sequential data X(t) of the force X.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for evaluating vibration characteristics of a tire. [Background technology]

[0002] Conventionally, methods for evaluating tire vibration characteristics have been known. For example, Patent Document 1 below describes a method for calculating tire input and characteristic parameters in tire vibration transmission characteristics from tire axial force vibrations generated when passing over a step on a road surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-096753 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the calculation method of Patent Document 1 requires repeated optimization calculations of the characteristic parameters, and data processing takes time.

[0005] The present disclosure has been devised in consideration of the above-described circumstances, and has as its main object to provide a tire vibration characteristic evaluation method capable of accurately evaluating the vibration characteristics of a tire in a short period of time. [Means for solving the problem]

[0006] The present disclosure relates to a method for evaluating vibration characteristics of a tire, the method including: a preparation step of preparing the tire and a drum testing machine including an axle on which the tire is mounted and a drum having a running surface with a step for the tire to overcome; a running step of mounting the tire on the axle of the drum testing machine and running the tire on the running surface; a measurement step of measuring time series data Y(t) of an axial force acting on the axle when the tire overcomes the step during the running step; and an evaluation step of evaluating vibration characteristics of the tire based on the time series data Y(t) of the axial force measured during the measurement step, The steps of the tire vibration characteristic evaluation method include a first step of calculating a natural angular frequency ω and a damping ratio ζ by performing frequency analysis on the time series data Y(t) of the axial force; a second step of inputting the natural angular frequency ω and the damping ratio ζ into a vibration transfer characteristic function to calculate a vibration transfer characteristic H(t) of the tire; a third step of calculating time series data X(t) of a force acting on the tire when the tire goes over the step by deconvolving the time series data Y(t) of the axial force using the vibration transfer characteristic H(t); and a fourth step of evaluating the vibration characteristics of the tire based on the time series data X(t) of the force. Effect of the Invention

[0007] The tire vibration characteristic evaluation method of the present disclosure, having the above-described configuration, can accurately evaluate the vibration characteristics of a tire in a short period of time. [Brief description of the drawings]

[0008] [Figure 1] 1 is a flowchart illustrating an embodiment of a tire vibration characteristic evaluation method according to the present disclosure. [Diagram 2] FIG. 2 is an enlarged schematic view of a drum testing machine on which a tire is mounted. [Diagram 3] 11 is a graph showing an example of time-series data of axial force. [Figure 4] 1 is a flowchart of an evaluation process. [Diagram 5] 13 is a graph showing an example of a frequency analysis result of time-series data of axial force. [Figure 6] 1 is a graph showing the results of an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. Fig. 1 is a flow chart showing a method for evaluating vibration characteristics of a tire 1 according to the present embodiment. As shown in Fig. 1, the method for evaluating vibration characteristics of a tire 1 according to the present embodiment includes a preparation step S1 for preparing a tire 1 to be evaluated for vibration characteristics and a drum testing machine 2.

[0010] Fig. 2 is an enlarged schematic diagram of a drum testing machine 2 on which a tire 1 is mounted. As shown in Fig. 2, the drum testing machine 2 of this embodiment includes a shaft 3 on which the tire 1 is mounted and a drum 4 on which the tire 1 comes into contact with the ground. The drum 4 of this embodiment has a running surface 4a provided with a step 5 for the tire 1 to overcome.

[0011] 1 and 2, in the method for evaluating vibration characteristics of a tire 1 according to the present embodiment, after a preparation step S1, a running step S2 is performed in which the tire 1 is mounted on an axle 3 of a drum testing machine 2 and allowed to run on a running surface 4a. Such a running step S2 is suitable for quantitatively evaluating the vibration characteristics of the tire 1.

[0012] In the vibration characteristic evaluation method for the tire 1 according to the present embodiment, in the traveling step S2, a measuring step S3 is carried out to measure the axial force Y acting on the axle 3 when the tire 1 goes over a step 5.

[0013] Fig. 3 is a graph showing an example of time series data Y(t) of the axial force Y. In Fig. 3, the horizontal axis represents time t, and the vertical axis represents the axial force Y. As shown in Fig. 3, the measurement process S3 of this embodiment measures the time series data Y(t) of the axial force Y. Such a measurement process S3 can measure the change over time t of the axial force Y due to the impact force when the tire 1 goes over a step 5.

[0014] As shown in FIG. 1, the method for evaluating vibration characteristics of a tire 1 according to this embodiment includes an evaluation step S4 for evaluating vibration characteristics of the tire 1 based on time-series data Y(t) of the axial force Y measured in the measurement step S3.

[0015] Fig. 4 is a flowchart of the evaluation step S4. As shown in Fig. 4, the evaluation step S4 of this embodiment first performs a first step S41 of calculating the natural angular frequency ω and the damping ratio ζ by performing frequency analysis on the time series data Y(t) of the axial force Y. Such an evaluation step S4 can calculate the natural angular frequency ω and the damping ratio ζ without repeated calculations.

[0016] In the evaluation process S4, it is preferable that after the first step S41, a second step S42 is performed in which the natural angular frequency ω and the damping ratio ζ calculated in the first step S41 are input into a vibration transfer characteristic function to calculate the vibration transfer characteristic H(t) of the tire 1.

[0017] The evaluation step S4 of this embodiment includes a third step S43 in which the vibration transmission characteristic H(t) calculated in the second step S42 is used to calculate time series data X(t) of the force X acting on the tire 1 when the tire 1 goes over the step 5. In the third step S43, it is preferable to calculate the time series data X(t) of the force X by deconvoluting the time series data Y(t) of the axial force Y.

[0018] Here, deconvolution is a matrix operation performed using an inverse matrix of a matrix used when obtaining time series data Y(t) of axial force Y from time series data X(t) of force X. Such an evaluation step S4 can calculate the time series data X(t) of force X acting on tire 1 in a short period of time.

[0019] In the evaluation step S4 of this embodiment, a fourth step S44 is performed to evaluate the vibration characteristics of the tire 1 based on the time series data X(t) of the force X calculated in the third step S43. In the fourth step S44, for example, the vibration characteristics of the tire 1 are evaluated based on an evaluation standard that is predetermined for each tire 1. Such an evaluation step S4 can perform accurate evaluation in a short time.

[0020] In a more preferred embodiment, the running speed of the tire 1 in the running step S2 is 1 to 120 km per hour. Such a running step S2 can satisfy various conceivable running conditions. Therefore, the method for evaluating vibration characteristics of the tire 1 according to the present embodiment can evaluate the vibration characteristics required for the tire 1.

[0021] 2, the cross-sectional shape of the step 5 perpendicular to the axis of the drum 4 is, for example, rectangular. However, the cross-sectional shape of the step 5 is not limited to this embodiment, and may be, for example, triangular, trapezoidal, or semicircular.

[0022] The height h of the step 5 is preferably 0.5 to 20 mm. Such a step 5 can accurately reproduce the step climbing that may actually occur in the market.

[0023] 4, in the evaluation step S4, for example, the frequency analysis in the first step S41 is performed by fast Fourier transform using an FFT analyzer. In such a first step S41, the frequency analysis can be performed in a short time.

[0024] Fig. 5 is a graph showing an example of the frequency analysis result of the time series data Y(t) of the axial force Y. In Fig. 5, the horizontal axis is frequency f and the vertical axis is axial force Y. As shown in Fig. 5, the natural angular frequency ω calculated in the first step S41 is calculated by the following formula (1) using, for example, the frequency f0 at which the axial force Y has a maximum value Ym from the result of the frequency analysis of the time series data Y(t) of the axial force Y.

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[0025] Here, the maximum value Ym in a predetermined region including the tire resonance frequency is used as the maximum value Ym of the axial force Y. In this evaluation step S4, the natural angular frequency ω can be calculated without repeated calculations.

[0026] The damping ratio ζ calculated in the first step S41 is, for example, a value calculated by a half-width method from the result of frequency analysis of the time series data Y(t) of the axial force Y. It is preferable to calculate the damping ratio ζ from the result of frequency analysis of the time series data Y(t) of the axial force Y by the following formula (2).

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[0027] Here, f0 is the frequency f at which the axial force Y is at the maximum value Ym, and f1 and f2 are the frequencies f at which the axial force Y is 1 / √2 times the maximum value Ym, and f2>f1. In this evaluation step S4, the damping ratio ζ can be calculated without repeated calculations. Note that the damping ratio ζ when the evaluation target is the tire 1 is calculated within the range of 0.00 to 0.15, for example.

[0028] It is preferable to employ the following formula (3) as the vibration transfer characteristic function for calculating the vibration transfer characteristic H(t) in the second step S42.

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[0029] Here, ω is the natural angular frequency ω, ζ is the damping ratio ζ, and t is time t. Such vibration transmission characteristics H(t) are useful for quickly calculating the matrix used for deconvolution in the third step S43.

[0030] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways. EXAMPLES

[0031] 1 to 5, time series data X(t) of the force X acting on the tire when the tire goes over a step was calculated. Since the force X acting on the tire during low-speed running is approximately equal to the axial force Y, the test compared the calculated time series data X(t) of the force X with the time series data Y(t) of the axial force Y. The test conditions were as follows:

[0032] <Test conditions> Tire size: 225 / 45R18 Air pressure: 150kPa Load capacity: 4.96kN Travel speed: 6km / h Step height h: 10mm Step cross-sectional shape: Square

[0033] The test results are shown in Fig. 6. In Fig. 6, the horizontal axis is time t, and the vertical axis is force X and axial force Y. As shown in Fig. 6, the test results show that the time series data X(t) of force X calculated in the embodiment is approximately consistent with the time series data Y(t) of axial force Y, and it was confirmed that the embodiment can accurately evaluate the vibration characteristics of a tire in a short time.

[0034] [Note] The present disclosure is as follows.

[0035] [Disclosure 1] A method for evaluating vibration characteristics of a tire, the method comprising: a preparation step of preparing the tire and a drum testing machine including an axle on which the tire is mounted and a drum having a running surface with a step for the tire to overcome; a running step of mounting the tire on the axle of the drum testing machine and running the tire on the running surface; a measurement step of measuring time series data Y(t) of an axial force acting on the axle when the tire overcomes the step during the running step; and an evaluation step of evaluating vibration characteristics of the tire based on the time series data Y(t) of the axial force measured during the measurement step. a second step of inputting the natural angular frequency ω and the damping ratio ζ into a vibration transfer characteristic function to calculate a vibration transfer characteristic H(t) of the tire; a third step of deconvoluting the time series data Y(t) of the axial force using the vibration transfer characteristic H(t) to calculate time series data X(t) of a force acting on the tire when the tire went over the step; and a fourth step of evaluating the vibration characteristics of the tire based on the time series data X(t) of the force.

[0036] [Disclosure 2] The tire vibration characteristic evaluation method according to the present disclosure 1, wherein the natural angular frequency ω is calculated from the result of the frequency analysis of the time series data Y(t) of the axial force by the following formula (1) using a frequency f0 at which the axial force has a maximum value:

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[0037] [Disclosure 3] The tire vibration characteristic evaluation method according to Disclosure 1 or 2, wherein the damping ratio ζ is calculated from the result of the frequency analysis of the time-series data Y(t) of the axial force by the following formula (2):

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[0038] [Disclosure 4] The tire vibration characteristic evaluation method according to any one of Disclosures 1 to 3, wherein the vibration transfer characteristic function for calculating the vibration transfer characteristic H(t) employs the following formula (3):

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[0039] [Disclosure 5] The method for evaluating vibration characteristics of a tire according to any one of Disclosures 1 to 4, wherein the running speed of the tire in the running step is 1 to 120 km per hour. [Explanation of symbols]

[0040] 1 Tire 2 Drum Testing Machine 5 steps

Claims

1. 1. A method for evaluating vibration characteristics of a tire, comprising: a preparation step of preparing the tire and a drum testing machine including an axle on which the tire is mounted and a drum having a running surface with a step for the tire to overcome; a running step of mounting the tire on the shaft of the drum testing machine and running the tire on the running surface; a measuring step of measuring time series data Y(t) of an axial force acting on the axle when the tire goes over the step in the traveling step; and evaluating vibration characteristics of the tire based on the time-series data Y(t) of the axial force measured in the measuring step, The evaluation step includes: A first step of calculating a natural angular frequency ω and a damping ratio ζ by frequency analyzing the time series data Y(t) of the axial force; a second step of inputting the natural angular frequency ω and the damping ratio ζ into a vibration transfer characteristic function to calculate a vibration transfer characteristic H(t) of the tire; a third step of calculating time series data X(t) of a force acting on the tire when the tire goes over the step by deconvolving the time series data Y(t) of the axial force using the vibration transfer characteristic H(t); and a fourth step of evaluating vibration characteristics of the tire based on the force time series data X(t). Method for evaluating tire vibration characteristics.

2. 2. The tire vibration characteristic evaluation method according to claim 1, wherein the natural angular frequency ω is calculated from a result of the frequency analysis of the time-series data Y(t) of the axial force by the following formula (1) using a frequency f0 at which the axial force has a maximum value: [0010]

3. 3. The tire vibration characteristic evaluation method according to claim 1, wherein the damping ratio ζ is calculated from the result of the frequency analysis of the time-series data Y(t) of the axial force by the following formula (2): [0025] Here, f0: Frequency at which the axial force reaches its maximum value f1, f2: Frequency at which the axial force is 1 / √2 times the maximum value (f2>f1)

4. 4. The tire vibration characteristic evaluation method according to claim 1, wherein the vibration transfer characteristic function for calculating the vibration transfer characteristic H(t) is expressed by the following formula (3): [0030] Here, ω: Natural angular frequency ζ: Damping ratio t: time

5. 5. The method for evaluating vibration characteristics of a tire according to claim 1, wherein the running speed of the tire in the running step is 1 to 120 km per hour.

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