JP2019007798A - Tire pattern noise evaluation method - Google Patents

Abstract

To evaluate pattern noise from pitch arrangement of tread pattern without forming an actual tire.SOLUTION: A tire pattern noise evaluation method includes a polymerization wave generation step and an evaluation step, and evaluates a variation sensation of a tread pattern in which a plurality of pitches 3 are arrayed in a peripheral direction of a tire. In the polymerization wave generation step, primary waves 5 in which waves range in a plurality of periods are generated for the respective pitches 3. The primary waves 5 are arrayed on the basis of the arrangement of the pitches 3 and superimposed on each other, so that a polymerization wave 6 of the pitches 3 is generated. In the evaluation step, pattern noise is evaluated on the basis of the polymerization wave 6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pattern noise evaluation method for tires that can suitably evaluate pattern noise, in particular, a sense of variation (growing) that is one of the causes of discomfort.

  In general, the pattern noise of a tire is evaluated based on a measured value of the sound pressure level.

  On the other hand, in recent years, as the overall sound pressure level decreases, it is necessary to consider sound quality as another parameter. For the evaluation of sound quality, a method is adopted in which tires having a tread pattern to be evaluated are actually created, and superiority or inferiority is evaluated based on the sensuality of skilled drivers by running an actual vehicle.

  Note that, as a sound quality evaluation index related to a sense of variation (a degree of temporal variation in sound volume) which is a main item of sound quality, variation intensity, roughness, and the like are known. However, these indices are also values obtained by analyzing sound pressure data measured with actual tires using a sound quality evaluation system. For example, it was difficult to evaluate the superiority or inferiority of the sense of variation from the pitch arrangement at the design stage. .

  The following Patent Document 1 relates to the sound quality of pattern noise.

Japanese Patent No. 3857389

  The present invention provides a tire pattern noise evaluation method that can suitably evaluate pattern noise, particularly a sense of variation, which is one of the causes of discomfort, from the pitch arrangement of a tread pattern without forming an actual tire. It is an issue.

The present invention is a tire pattern noise evaluation method in which a plurality of pitches constituting a pattern constituent unit are arranged in the tire circumferential direction on a tread surface,
For each pitch, create a primary wave in which waves are connected in a plurality of cycles, and arrange and superimpose the primary waves corresponding to each pitch based on the arrangement of the pitch to create a superposition wave of the pitch Creation process,
And an evaluation step of evaluating pattern noise based on the superposed wave of the pitch.

  In the tire pattern noise evaluation method according to the present invention, the primary wave is preferably a sine wave.

  In the tire pattern noise evaluation method according to the present invention, the sine wave preferably has a wavelength equal to the pitch length P of each pitch.

  In the tire pattern noise evaluation method according to the present invention, it is preferable that the number n of cycles of the waves forming the primary wave is determined according to the traveling speed to be evaluated.

In the tire pattern noise evaluation method according to the present invention, it is preferable that the number n of the periods of the waves forming the primary wave is obtained by the following equation (1).
n = v * t / L * N --- (1)
v is the running speed to be evaluated (m / sec)
t is the decay time, 0.02-0.04 (sec)
L is the circumference of the tread surface (m)
N is the total number of pitches

In the tire pattern noise evaluation method according to the present invention, the decay time t is preferably obtained by the following equation (2).
t = −0.000129 × v + 0.036562 −−− (2)

In the tire pattern noise evaluation method according to the present invention, in the evaluation step, an amplitude variation waveform in the superposed wave is obtained from the superposed wave,
It is preferable to evaluate the pattern noise based on a first-order Fourier coefficient obtained by Fourier transforming the amplitude fluctuation waveform.

  As described above, according to the present invention, primary waves corresponding to the respective pitches are arranged and superposed on the basis of the pitch arrangement to create a superposed wave of the pitch, and pattern noise is evaluated based on the superposed wave of the pitch. To do.

  As a result of the inventor's research, in pitch noise, there is a time lag from when a sound is generated from one pitch until the sound is no longer felt, and this time lag is one of the causes of fluctuation in pitch noise. I found out that there was. The decay time of the pitch sound, which is this time lag, is about 0.02 to 0.04 sec, and varies depending on the running speed of the tire.

  Therefore, in consideration of this decay time, each pitch is regarded as a primary wave in which waves are connected in a plurality of periods, and this primary wave is arranged and superposed based on the pitch arrangement to create a superimposed wave of pitches. . That is, this superposed wave is an interference wave in which sounds from each pitch including the sound that can be heard during the decay time interfere with each other, and includes the above-mentioned factors of fluctuation.

  Therefore, by using the superposed wave, it becomes possible to evaluate the pattern noise, particularly w of the pattern noise.

1 is a perspective view conceptually showing one embodiment of a tire in which a pattern noise evaluation method of the present invention is adopted. It is a diagram which illustrates the primary wave created for every pitch. It is a diagram which illustrates a superposition wave creation process notionally. It is a diagram which shows the superposition | polymerization wave produced by the superposition | polymerization wave preparation process. It is a diagram which shows the upper and lower envelopes of a polymerization wave. It is a diagram which shows the fluctuation waveform of the amplitude in a superposition | polymerization wave. It is a graph which shows the relationship between the decay time of pitch sound, and the running speed of a tire.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, the tire 1 of the present embodiment includes a tread pattern in which a plurality of pitches 3 constituting a pattern constituent unit are arranged in the tire circumferential direction on a tread surface 2.

  The pattern constituent unit is not particularly limited, and various pattern shapes formed based on tread grooves including lug grooves extending in the direction intersecting with the tire circumferential direction can be adopted as in the past. .

The pitch (pattern constituent unit) 3 is composed of a plurality of types of pitches having different pitch lengths that are circumferential lengths. In this example, consists of the pitch 3, the first pitch 3S pitch length P _S, and the second pitch 3M pitch length P _M, pitch length and the third pitch 3L of P _L The case is shown. In this example, these three types of pitches 3 (first to third pitches 3S to 3L) are arranged in the tire circumferential direction in a predetermined order.

  Next, a pattern noise evaluation method using this tire 1 will be described. This pattern noise evaluation method includes a superimposed wave creation step and an evaluation step.

In the polymerization wave creating step,
A) creating a primary wave 5 consisting of a plurality of cycles of waves for each pitch 3;
A) arranging the primary waves 5 corresponding to the respective pitches 3 on the basis of the arrangement of the pitches 3 and superposing them to form the superposed wave 6 having the pitch 3;

FIG. 2 shows a primary wave 5S of the first pitch 3S, a primary wave 5M of the second pitch 3M, and a primary wave 5L of the third pitch 3L. In this example, the primary waves 5S, 5M, and 5L are each formed from a sine wave in which the waves are continuous in six periods. Specifically, the primary waves 5S, 5M, and 5L are represented by the following equations, respectively. In the formula, x is a distance (unit: mm) in the traveling direction on the tread surface 2, and λ is a wavelength (unit: mm).
y = sin (2π × / λ)

Particularly preferably, each wavelength λ of the primary waves 5S, 5M, and 5L is preferably equal to the pitch length P. That is, in this embodiment, the primary wave 5S is a sine wave having a wavelength of P _S and 6 cycles, the primary wave 5M is a sine wave having a wavelength P _M and 6 cycles, the primary wave 5L wavelength P _L and the six periods sine Formed as a wave.

  Here, the number n (not necessarily an integer) of the period of the waves forming the primary wave 5 is set according to the traveling speed to be evaluated.

  As described above, with pitch noise, there is a time lag from when a sound is generated from one pitch 3 until the sound is no longer felt, and this time lag is one of the causes of fluctuation in pitch noise. . As shown in FIG. 7, the decay time t of the pitch sound, which is a time lag, is in the range of 0.02 to 0.04 sec, and strictly varies depending on the running speed of the tire. Note that the pitch sound decay time t in FIG. 7 was obtained from the results of experiments by the inventors.

  Therefore, in consideration of the decay time t, each pitch 3 is regarded as a primary wave 5 in which waves are connected at a plurality of periods.

Specifically, the number n of cycles of the primary wave 5 can be obtained by the following equation (1). In the equation, v is a running speed (m / sec) of a tire to be evaluated, t is a decay time, and is selected from a range of 0.02 to 0.04 (sec). L is the circumference (m), which is the circumference of the tread surface 2, and N is the total number (pieces) of the pitch 3.
n = v * t / L * N --- (1)

For example, when running at a speed of 36 km / h (corresponding to v = 10 m / sec) in the tire 1 in which the circumferential length L of the tread surface 2 is 2 m and the total number N of pitches 3 constituting the pattern unit is 60. When evaluating the fluctuation feeling of the pattern noise, the number n of the periods of the primary wave 5 is set when the decay time t is 0.02 sec.
n = 10 × 0.02 / 2 × 60 = 6
It becomes. When the decay time t is 0.04 sec, n = 12.

Particularly preferably, the decay time t is desirably obtained by the following equation (2).
t = −0.000129 × v + 0.036562 −−− (2)
When Expression (2) is used, t≈0.035, and n = 10.5. Equation (2) is a linear regression equation obtained by regression analysis of the experimental result shown in FIG.

  Next, in the superposition wave creation step, as shown in FIG. 3, the step of creating the superposition wave 6 (shown in FIG. 4) having the pitch 3 by arranging and superimposing the primary waves 5 on the basis of the pitch arrangement. Have.

As shown in FIG. 1, when the reference position is J, in this example, the pitch 3 is arranged in the order of 3S ₁ → 3M ₂ → 3S ₃ → 3L ₄ → 3M ₅ → 3L ₆ . . Therefore, as shown in FIG. 3, the primary wave 5 is arranged based on this arrangement.

Specifically, firstly, in response to the pitch 3S _1, the primary wave 5S is, starting from the reference position J. Then, in response to the pitch 3M _2, the primary wave 5M is, starting from spaced positions on the pitch length P _S from the reference position J. Next, corresponding to the pitch 3S ₃ , the primary wave 5S starts from a position separating the pitch length P _S + P _M from the reference position J. Next, corresponding to the pitch 3L ₄ , the primary wave 5L starts from a position separating the pitch length P _S + P _M + P _S from the reference position J. Then, in response to the pitch 3M _5, the primary wave 5M is, starting from the reference position J spaced a pitch length _{P S + P M + P S} + P L from the position. Then, in response to the pitch 3L _6, the primary wave 5L is, starting from the reference position J spaced a pitch length _{P S + P M + P S} + P L + P M from the position.

  Thus, based on the arrangement | sequence of the pitch 3, while arrange | positioning the primary wave 5 over a tire circumference and superimposing the primary wave 5 arrange | positioned over a tire circumference, the superposition | polymerization wave 6 shown in FIG. 4 is calculated | required. . The superimposed wave 6 is an interference wave in which sounds from the pitches 3 including the sound that can be heard at the decay time t interfere with each other, and includes the factors of the fluctuation.

Next, in the evaluation step, pattern noise, particularly a sense of variation is evaluated based on the superposed wave 6. In particular,
C) obtaining a fluctuation waveform 7 of the amplitude in the superposed wave 6 from the superposed wave 6, as shown in FIG.
D) Fourier transforming the fluctuation waveform 7 of the amplitude, and evaluating the sense of fluctuation based on the first-order Fourier coefficient obtained thereby.

  For example, as shown in FIG. 5, the amplitude fluctuation waveform 7 is obtained by obtaining an envelope 8U and a lower envelope 8L from the superposed wave 6, and an upper envelope 8U and a lower envelope 8L. It can be obtained by taking out the amplitude which is the vertical distance D between 8L.

  The reason for evaluating the sense of variation based on the first-order Fourier coefficient is as follows. It is known that humans are most likely to feel a 4Hz fluctuating sound with respect to the “fluctuation” that senses temporal fluctuations in sound pressure. Also, the speed at which it is easy to feel “fluctuation” during driving is empirically around 30 to 40 km / h, and the fluctuation of 4 Hz during driving at a speed of 30 to 40 km / h in a general passenger car tire size. The tire rotation order corresponding to is the first order. For this reason, the magnitude of the primary fluctuation is used as an index of “fluctuation”.

In this example, the pitch lengths P _S , P _M , and P _L of the respective pitches 3S, 3M, and 3L are applied as the wavelengths λ in the primary waves 5S, 5M, and 5L. However, the wavelengths λ of the primary waves 5S, 5M, and 5L may be the same. In this case, the wavelength lambda, for example the pitch length _{P S,} P M, it is desirable to average values of _{P L} and _{(P S + P M + P} L) / 3, or a pitch length closer to the average value, for example, _{P M} suitable .

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

In order to confirm the effect of the present invention, tires (195 / 65R15) A, B, and C having a tread pattern having a pitch arrangement shown in Table 1 were manufactured. Common specifications in the tread pattern are as follows.
* Number of types of pitch (pattern composition unit) (3)
First pitch 3S --- Pitch length P _S (21 mm)
Second pitch 3M --- Pitch length P _M (25 mm)
Third pitch 3L --- Pitch length P _L (30 mm)
* Tread surface circumference L (1.99m)
* Total number of pitches N (66)

  Fluctuation in pattern noise of each prototype tire A, B, C was evaluated based on the superposed wave according to the present invention. Further, as a conventional example, the vehicle was run using prototype tires A, B, and C, and the sense of variation was evaluated by sensory evaluation of the driver at that time.

In Examples 1 and 4, the number of primary wave periods n is calculated using the formulas (1) and (2) when traveling at a speed of 30 km / h (corresponding to v≈8.3 m / sec). Value.
n = v * t / L * N --- (1)
t = −0.000129 × v + 0.036562 −−− (2)
In the second and third embodiments, the number of primary wave periods n is a value determined irrespective of the equations (1) and (2).

  In each of the examples, the value of the fluctuation index is a value of a first-order Fourier coefficient obtained by Fourier-transforming the amplitude fluctuation waveform in the superimposed wave. A smaller value indicates less fluctuation and better.

In the conventional example, the value of the index of variation is a value obtained by evaluating the sense of variation when the vehicle is driven under the following conditions by a ten-point method based on sensory evaluation of the driver. Larger values are better with less fluctuation.
Rims: 15 × 6.0J
Vehicle: Prius of TOYOTA Traveling speed: 20-40km / h (It is easy to feel fluctuation at 30km / h in sensuality.)
Road surface: Smooth asphalt road Location: Okayama test course of Sumitomo Rubber Industries

  As shown in Table 2, the example has a high correlation with the conventional example, and it can be confirmed that the variation in pattern noise can be evaluated from the pitch arrangement of the tread pattern without forming an actual tire. .

1 tire 2 tread surface 3, 3S, 3M, 3L pitch 5, 5S, 5M, 5 primary wave 6 superposed wave 7 fluctuation waveform

Claims (7)

A tire pattern noise evaluation method in which a plurality of pitches constituting a pattern constituent unit are arranged in a tire circumferential direction on a tread surface,
For each pitch, create a primary wave in which waves are connected in a plurality of cycles, and arrange and superimpose the primary waves corresponding to each pitch based on the arrangement of the pitch to create a superposition wave of the pitch Creation process,
A tire pattern noise evaluation method including an evaluation step of evaluating pattern noise based on the superposed wave of the pitch.   The tire pattern noise evaluation method according to claim 1, wherein the primary wave is a sine wave.   The tire pattern noise evaluation method according to claim 2, wherein the sine wave has a wavelength equal to a pitch length P of each pitch.   The tire pattern noise evaluation method according to any one of claims 1 to 3, wherein the number n of cycles of the waves forming the primary wave is determined according to a traveling speed to be evaluated. The tire pattern noise evaluation method according to any one of claims 1 to 4, wherein the number n of cycles of the waves forming the primary wave is obtained by the following equation (1).
n = v * t / L * N --- (1)
v is the running speed to be evaluated (m / sec)
t is the decay time, 0.02-0.04 (sec)
L is the circumference of the tread surface (m)
N is the total number of pitches 6. The tire pattern noise evaluation method according to claim 5, wherein the decay time t is obtained by the following equation (2).
t = −0.000129 × v + 0.036562 −−− (2) In the evaluation step, from the superposition wave, obtain a fluctuation waveform of the amplitude in the superposition wave,
The tire pattern noise evaluation method according to any one of claims 1 to 6, wherein pattern noise is evaluated based on a first-order Fourier coefficient obtained by Fourier transforming the fluctuation waveform of the amplitude.

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