JP2003136926A - Method and program for evaluating noise of tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire noise evaluating method which can evaluate the noise by the simulation based on the data of the tread pattern. SOLUTION: This tire noise evaluating method comprises a step of storing the data on the tread pattern of the tire, a step of storing the data of a ground contact pattern S of the tire to a road surface, a step of scanning the ground contact pattern S along the circumferential direction of the tread pattern, a step of acquiring the fluctuation data on the contact area of a tread part, and a step of acquiring the frequency analysis data based on the fluctuation data of the ground contact area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire noise evaluation method and program capable of obtaining noise evaluations of tires having various tread patterns by simulation.

[0002]

2. Description of the Related Art As a cause of noise generated when a pneumatic tire (hereinafter, simply referred to as a tire) travels, there are known pumping sound, pattern vibration sound, and so on (so-called pattern noise). The pumping sound compresses the air when the groove of the pattern steps into the ground,
The pattern vibration sound is the sound generated when air is released when the tread pattern collides with the road surface when the tread pattern touches the ground, and the tire vibration vibrates due to the impact force at that time. Is.

Of the above pattern noises, particularly the pattern vibration sound has a remarkable frequency component (first-order component) determined by the tire pitch number and rotation number. Here, the tire pitch refers to the minimum unit of the repeated pattern in the tire circumferential direction that constitutes the tread pattern.

Since the pattern vibration sound causes noise depending on the frequency component of the pitch as described above, a technique called pitch variation is used to disperse the frequency components and the noise is hard to hear. There is. That is, the noise level is reduced by converting the noise into white noise. In pitch variation, a method of changing the difference in pitch length between pitches and randomizing the pitch arrangement is used.

Further, the tread pattern of the tire is divided by circumferential grooves formed along the tire circumferential direction (hereinafter, the divided areas may be referred to as "circumferential pitch group"). By making the pitch arrangements of the respective circumferential pitch groups different from each other, the number of kinds of pitches is smaller and it is more effective against noise due to noise. A tread pattern having such a pitch arrangement is disclosed in Japanese Patent Application Laid-Open No. 2000-43507 by the present applicant.

The noise reduction effect of the tire using the pitch variation method as described above needs to be confirmed by a sensory test or the like by actually manufacturing a tire having the tread pattern.

[0007]

However, it is time-consuming and inefficient to actually manufacture and confirm tires for all the tread patterns studied at the development stage. Further, also in the tread pattern using the pitch variation, when the pitch arrangement of the circumferential pitch groups arranged along the tire width direction is made different, the variation is wide. Also, when deciding the tread pattern, there are trial and error aspects, and therefore the number of tread patterns (pitch arrangements) to be considered is considerably large. Finally, although it is necessary to confirm and evaluate the tire after manufacturing it, it is preferable to narrow down the types of tread patterns by simulation to some extent.

Further, when the tire noise is evaluated by the simulation, it is not enough to perform only the pitch arrangement. For example, in the tire noise evaluation method disclosed in Japanese Patent Laid-Open No. 11-23357, a time-series waveform in which rectangular waves having a predetermined constant pulse width are arranged at time intervals proportional to each pitch length of the pitch arrangement. The pattern noise is approximated by. However, the generated noise depends not only on the pitch arrangement but also on the way of grounding on the road surface. Therefore, it is necessary to perform a simulation that considers how to make contact with the road surface.

The present invention has been made in view of the above-mentioned circumstances, and its problem is that the noise of a tire can be evaluated by a simulation based on the data of the tread pattern in consideration of the way of touching the road surface. An evaluation method and a tire noise evaluation program are provided.

In order to solve the above problems, a tire noise evaluation method according to the present invention comprises a step of storing data of a tire tread pattern and a step of storing data of a ground contact pattern with respect to a road surface of the tire. A step of scanning the ground pattern along the circumferential direction of the tread pattern; a step of acquiring variation data of the ground area of the tread portion by the scanning step; and a frequency analysis based on the variation data of the ground area. And a step of acquiring data.

Each step of the tire noise evaluation method according to this configuration can be executed by a computer. First, tread pattern data is stored. The tread pattern can be stored in the storage device as image data, for example. Next, the data of the ground contact pattern for the road surface of the tire is stored. The ground contact pattern is data acquired from the shape of the ground contact area when the tire contacts the road surface. The grounding pattern is the shape of the tire,
It can be determined (or set) by tire load, tire internal pressure, etc.

Next, this ground pattern is scanned along the circumferential direction of the tread pattern. This simulates the same condition as running a tire. By scanning the ground pattern, it is possible to obtain variation data of the ground area of the tread portion. Frequency analysis data can be obtained based on this fluctuation data,
Noise evaluation can be performed from this data.

As described above, according to the present invention, the noise evaluation is performed not only by the pitch arrangement but by considering the ground pattern. Therefore,
Simulation with good reading accuracy is possible. As a result, it is possible to provide a tire noise evaluation method capable of performing noise evaluation in consideration of how to contact the road surface by a simulation based on tread pattern data.

As a preferred embodiment of the present invention, the grounding pattern is defined by a grounding line at the start of tire grounding.

By defining the ground pattern by the ground line, the calculation time for obtaining the ground area can be shortened.

As another preferred embodiment of the present invention, the tread pattern data is image data composed of at least a ground portion and a non-ground portion, and the area of the ground portion existing on the ground pattern is defined as An example is one that obtains the variation data of the ground contact area by obtaining it.

According to this structure, the area of the ground portion existing on the ground pattern is obtained. By scanning the grounding pattern along the circumferential direction of the tread pattern, it is possible to acquire the variation data of the grounding area. The ground area can be acquired by counting the number of pixels of the ground portion existing on the ground pattern, for example.

As still another preferred embodiment of the present invention,
In obtaining the frequency analysis data, there is one that has a step of extracting a noise level in a specific frequency range at an audible frequency.

What is important in noise evaluation is the noise level in a specific frequency range that is audible to the human ear. Therefore, a more accurate simulation can be performed by extracting the noise level in the specific frequency range from the acquired frequency analysis data.

A program for realizing the tire noise evaluation method according to the present invention by a computer includes a process of storing data of a tire tread pattern, a process of storing data of a ground pattern of a tire road surface,
A process of scanning the ground pattern along the circumferential direction of the tread pattern, a process of acquiring variation data of the ground area of the tread portion by the scanning step, and frequency analysis data based on the variation data of the ground area. It is characterized by causing a computer to execute the processing to be acquired.

The problem of the present invention can be solved by installing such a program in a computer. For the installation method, see the CD
-It can be performed by an appropriate method such as a method using a ROM.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of a tire noise evaluation method according to the present invention will be described with reference to the drawings. First, FIG. 1 is a diagram showing a configuration of a system for implementing a tire noise evaluation method.

The present system can be realized by using a computer such as a personal computer. In FIG. 1, the CPU
Calculates and controls based on the program. An OS and various application programs are installed in the hard disk 1, and a tire noise evaluation program is also stored in the hard disk 1. When the tire noise evaluation program is executed, it is read into the RAM as appropriate. The monitor 2 displays the result calculated by the program. From the keyboard 3, various data for tire noise evaluation are input.

Next, the tread pattern of the tire will be described. Two types of tread patterns are illustrated in FIGS. 2 (a) and 2 (b). FIG. 2 is a plan development of a part of the tread pattern, and the arrow A direction indicates the tire circumferential direction,
The arrow B direction indicates the tire width direction. The tread pattern includes a plurality of main grooves 10 along the tire circumferential direction and the main grooves 10
A large number of sub-grooves 11 are formed so as to traverse. In the illustrated example, the sub groove 11 is inclined with respect to the main groove 10, but may be orthogonal to the main groove 11. The block defined by the main groove 10 and the sub groove 11 is called a pitch 12. The pitch 12 has a pitch length along the tire circumferential direction, and the pitch 1 has three types of pitch lengths (a, b, c).
Have two. The tread pattern has a large number of pitches with different pitch lengths arranged along the tire circumferential direction.

The tread pattern can be divided into a plurality of sections (circumferential pitch groups) by the main groove 10. In the example of FIG. 2, the drawing numbers 13a, 13b, 13c,
A tread pattern is composed of four circumferential pitch groups 13d. The circumferential pitch groups 13a and 13d located on the outer side in the tire width direction have the same pitch arrangement (a, b, b,
c, c, a ...). However, with respect to one circumferential pitch group 13d, the other circumferential pitch group 13a
Has a shift amount (phase difference) of only δ1.

Further, the circumferential pitch groups 13b and 13c located on the inner side in the tire width direction also have the same pitch arrangement (but different from the outer side), but one circumferential pitch group 13c is opposed to the other circumferential pitch group 13c. Similarly, the direction pitch group 13b has a shift amount of δ1. That is, FIG.
Both the lower circumferential pitch groups 13a and 13b have a shift amount of δ1 with respect to the upper circumferential pitch groups 13c and 13d in (a).

FIG. 2B shows an embodiment having another tread pattern. One circumferential pitch group 13a on the outer side in the tire width direction has a deviation amount of δ2 with respect to the other 13d. One circumferential pitch group 13b on the inside
Has a deviation amount of δ3 with respect to 13c with respect to the other,
Moreover, it is opposite to the case where the shift direction is δ2. In the example of FIG. 2, the pitch lengths are three types, a, b, and c. Of course, tread patterns having four or more types of pitch lengths are also conceivable.

<Procedure of Noise Evaluation Method> Next, the procedure for noise evaluation will be described. First, a tread pattern is created by CAD. Next, color-coding processing is performed on the grounded portion, the non-grounded portion, and the edge portion. FIG. 3B shows an image resulting from the processing. The black portion in the image is the grounding portion, which indicates the area actually grounded on the road surface. The non-grounded part is shown in white. Image data representing this tread pattern is stored in the hard disk.

Next, a ground pattern is defined and input.
The ground contact pattern can be defined based on the ground contact area when the tire contacts the road surface. The grounding line (indicated by symbol S in FIG. 4) when the tire starts to ground is defined as a grounding pattern in the grounding area. This ground contact pattern can be determined (set) by the load acting on the tire, the tire shape, the tire internal pressure, and the like. The ground pattern is also stored in a predetermined file format.

Next, this ground contact pattern is scanned along the tire circumferential direction (see FIG. 3A). This is the same state as running the tire. By changing the scanning speed, the traveling speed can also be changed. Next, the variation data of the tire contact area is acquired.
The ground contact area can be determined by the area of the ground contact portion existing on the ground contact pattern. That is, the ground area can be obtained by counting the number of pixels of the ground portion existing on the ground pattern.

FIG. 4B is a graph showing variation data of the ground contact area. The horizontal axis corresponds to the distance along the tire circumferential direction, and the vertical axis indicates the ratio (%) of the ground contact portion as the ground contact area variation data. Based on the variation data of the contact area, the result of frequency analysis is shown in FIG. 4 (c).
Shown in. In this figure, the horizontal axis represents frequency (Hz) and the vertical axis represents noise level (dB). Noise evaluation can be performed from this graph.

The ground area variation data shown in FIG. 4B is data for the entire area of the tread pattern, but partial data can also be obtained. Figure 5
(A) shows the variation data of the ground contact area of one shoulder portion of the tread pattern. The shoulder portion is a portion located on both sides in the tire width direction, and is a portion located between the tread portion and the sidewall portion. (B)
Indicates variation data of the central portion in the tire width direction. (C)
Shows variation data of the shoulder portion on the opposite side to (a). By performing frequency analysis based on such partial ground area variation data, it is possible to predict which part of the entire tread pattern will be improved.

The analysis shown in FIG. 4 is not performed over the entire circumference of the tire. It is an example in which a predetermined length region along the tire circumferential direction is evaluated. Next, an example in which the entire circumference in the tire circumferential direction is evaluated will be described.

First, a pitch arrangement drawing (image data) is created over the entire circumference of the tire (see FIG. 6). In addition,
The tread pattern can be created by combining pitches selected in advance. Fig. 8 shows the minimum unit basic data for creating the image data of the tread pattern.
Shown in. In the case of three types of pitch length, as shown in FIG.
Basic data corresponding to the pitch lengths of b and c are prepared. Also, specify the number of each pitch to be used. Further, when a plurality of pitches are arranged side by side along the tire circumferential direction, they can be randomly generated. A large number of tread patterns can be examined by trial and error by randomly generating various tread patterns. In addition, the shift amount as described in FIG. 2 can be input and set.

After the image data of the tread pattern of the entire circumference of the tire is created, next, the ground contact pattern is set and scanning is performed in the tire circumferential direction. FIG. 7A is a diagram showing variation data of the contact area. FIG.7 (b) is a figure which shows a frequency analysis result.

FIG. 9 is a graph comparing the frequency analysis results in a certain pitch arrangement. A good arrangement in this figure is shown in FIG. 10A, and the deviation amount is 0.4 mm on the inner side (corresponding to δ3 in FIG. 2) and the deviation amount on the outer side (δ in FIG. 2).
2) is 5.0 mm. The bad arrangement is shown in Fig. 10.
As shown in (b), the amount of displacement is 0.1 mm on the inside and 2 on the outside.
It is 1.5 mm.

Further, when performing noise evaluation based on the frequency analysis data, it is preferable to evaluate the noise level in a specific frequency range within the audible frequency band. The range surrounded by the dotted line in FIG. 9 is the range of the specific frequency, specifically, 447 to 561 Hz, 920 to 1070.
The Hz range is selected. Since a certain frequency of the audible frequency tends to be audible to the human ear,
It is preferable to evaluate the noise level at this specific frequency. In the example of FIG. 9, the noise level is lower in the good arrangement (configuration of the present invention) than in the bad arrangement (conventional configuration).

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a system for implementing a tire noise evaluation method.

FIG. 2 is a plan development view of a part of the tread pattern.

FIG. 3 is a diagram showing a tread pattern image.

FIG. 4 is a diagram showing variation data of ground contact area and frequency analysis data.

FIG. 5 is a diagram showing variation data of a contact area of each portion in the tire width direction.

FIG. 6 is a pitch arrangement diagram (tread pattern) created over the entire circumference of the tire.

FIG. 7 is a diagram showing variation data of a contact area and variation data of an edge point.

FIG. 8 is a diagram showing a pitch.

FIG. 9 is a diagram showing a graph comparing frequency analysis results in a certain pitch arrangement.

FIG. 10 is a diagram showing an array example in which the simulation of FIG. 9 is performed.

[Explanation of symbols]

10 main groove 11 Secondary groove 12 pitch 13a, 13b, 13c, 13d circumferential pitch group δ1, δ2, δ3 deviation A tire circumferential direction

Claims (5)

[Claims] 1. A step of storing data of a tire tread pattern, a step of storing data of a ground contact pattern with respect to a road surface of a tire, a step of scanning the ground contact pattern along a circumferential direction of the tread pattern, A tire noise evaluation method comprising: a step of acquiring variation data of a contact area of a tread portion by a scanning step; and a step of obtaining frequency analysis data based on the variation data of the contact area. 2. The tire noise evaluation method according to claim 1, wherein the ground contact pattern is defined by a ground contact line at the start of tire ground contact. 3. The tread pattern data is image data composed of at least a grounded portion and a non-grounded portion, and the ground contact area variation data is obtained by determining the area of the grounded portion existing on the ground pattern. The tire noise evaluation method according to claim 1 or 2, characterized by acquiring. 4. The step of extracting a noise level in a specific frequency range at an audible frequency in obtaining the frequency analysis data.
3. The tire noise evaluation method according to any one of 3 above. 5. A process of storing data of a tire tread pattern, a process of storing data of a ground contact pattern for a road surface of a tire, a process of scanning the ground contact pattern along a circumferential direction of the tread pattern, A tire noise evaluation program characterized by causing a computer to execute a process of acquiring variation data of a ground contact area of a tread portion by a scanning step, and a process of obtaining frequency analysis data based on the variation data of the ground contact area. .