JPS6116108A - Inflated tyre - Google Patents

Abstract

PURPOSE:To cause noise to be dispersed throughout a wider frequency band, by a method wherein pitches of tread patterns on both sides with a tread central line therebetween are arranged asymmetrically. CONSTITUTION:Pitches of tread patterns on a right side 4 and a left side 3 with a central line 2 therebetween are arranged asymmetrically when the whole of a tyre is seen. Preferably, regularity of pitch arrangement on the left side is the same as that of pitch arrangement on the right side, and the arranging directions on the right and the left side are reveres to each other. This enables noise to be dispersed through a wider frequency band, resulting in production of an effect in which reduced noise is felt by a human body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire having a specific tread pattern, and this tire is primarily used for automobiles.

[Prior art]

To date, many inventions have been made regarding methods for reducing tire noise, particularly pattern noise caused by the tire pattern.

These basically occur when several types of pattern elements with different pitch lengths (length of minimum repeating unit of trend pattern) are arranged appropriately in the circumferential direction of the tire, and each tread pattern element leaves the ground contact surface. This is a method of changing the time interval of pulse-like vibrations to prevent vibrations from concentrating on a specific frequency, and its main purpose is to reduce noise by using the variable pitch method based on frequency modulation theory used in radio engineering etc. It is said that

Conventionally, when using this barrier pull pitch method, one side of the tire tresocenter center line (equator line) (hereinafter referred to as "A type")
and the other side (hereinafter referred to as "Type B"), the pitches are arranged in the same direction with respect to the tire circumferential direction, that is, the entire tire trend is treated as one repetition unit and the barrier pull pitch method is used. There is also a certain limit to dispersion, and the current situation is that the noise level has not yet reached a satisfactory level.

On the other hand, there are the following problems in the manufacturing method of molds, and it is difficult to realize a pitch array with good dispersion obtained from frequency modulation theory, or the manufacturing process is complicated and costs are relatively high. Sometimes it happens.

A tire curing mold is generally divided into two along the tire center line, and the pitch arrangement of the tread pattern is P, P2. ...P, then this mold is divided into two parts from the tire center line as shown in Fig. 2 (b) and (C), and when viewed from the inside, the A type and B type are respectively P in the opposite direction, P2. ... is arranged as Pn. Further, the tread design portion of these molds is manufactured in half molds using a casting method called the OCR method.

Therefore, in order for Type A and Type B to be arranged in opposite directions as shown in Figures 2(b) and (C), the master model of the casting mold must be made of both halves as shown in Figure 3. It must be made with an array that can be shared by types. However, the master model production cost accounts for a high proportion of the mold production cost, and it is common practice to try to reduce the number of types of master models as much as possible. Therefore, the degree of freedom in pitch arrangement is narrowed, and sufficient noise reduction is not achieved. The current situation is that it has not been effective.

Furthermore, since types A and B are substantially different, the yield and mold management will essentially be twice as long.

[Purpose of the invention]

An object of the present invention is to provide a pneumatic tire that reduces noise caused by a tread pattern and also reduces mold manufacturing costs.

[Structure of the invention]

Therefore, the gist of the present invention is a pneumatic tire characterized in that the pitch arrangement of the tread pattern in the circumferential direction of the tire is asymmetrical on the left and right sides of the tire.

Preferably, the asymmetry is a pneumatic tire in which the arrangement order is the same but the arrangement direction is reversed.

Hereinafter, the configuration of the present invention will be specifically explained.

The pitch arrangement of the tread pattern in the present invention refers to the arrangement of repeating patterns in the trend portion.

FIG. 1 is a diagram showing a part of a tread pattern in which the pitch arrangement of the tread pattern of the present invention can be performed. Here 1 is the pattern, 2 is the center line of the tire (equatorial line)
, 3 is the left side, 4 is the right side, and P is the pattern pitch (Figure 1 shows a part where the same pattern 1 is continuous on both the left and right sides, and does not show whether it is symmetrical around the entire tire circumference.) .

In the present invention, the pitch arrangement of this tread pattern must be asymmetrical on the right side 4 and left side 3 of the centerline 2 when looking at the entire tire. There are many asymmetric configurations, but a preferred one is one in which the regularity of the pitch arrangement on the left side is the same as the regularity of the pitch arrangement on the right side, but the arrangement direction is reversed.

〔Example〕

The inventors have developed an A- and B-type pi divided by the tire center line of Tire Trend Design.

We considered dispersing the noise over a wider frequency range than before by creating different arrays for each array, and conducted the following experiments.

In the experiment, 165SR13 steel radial tires were used with the basic pattern shown in FIG. 1.

The pattern is L = 36.5mm, M = 29.
It has three types of pitch lengths: 8 mm and S = 23.4 mm. Figure 4(a) follows the conventional arrangement method.
Both types A and B have the same phase arrangement. Also, Figure 4 (
b) uses the same arrangement as in Fig. 4(a), but the A type and B type are arranged in opposite directions, and the entire tread pattern (
The combination of types A and B) is completely different from that shown in FIG. 4(a) and has a substantially different arrangement on one side of the tread pattern than on the other side. Figure 4 (C) shows that type A is shown in Figure 4 (a).
) and Fig. 4(b) are used, but type B is combined with a different arrangement. Therefore, in the case of Fig. 4 (C), when considering the entire tread pattern, it has a different arrangement from Fig. 4 (a) and Fig. 4 (b), but one side of the tread and the other side are different from each other. It is similar to FIG. 4(b) in the sense that it has a different arrangement.

Regarding the above three types of pitch arrangements, the present inventors conducted a tire noise test and determined that the measurement method was JASOC60.
The single bench test of the tire noise test method described in No. 6-81 was followed.

The tire noise tests shown in Figures 4 (a), (b), and (C) were carried out, and the results of examining their frequency characteristics were summarized in Figure 5.
Shown in the figure.

As shown in Figure 5, data (a) has an array in which types A and B are similar, data (b) has an array in which type B is the reverse of type A, and type B is completely different from type A. It is clearly seen that the data (C) with a different arrangement has a low sound pressure level in the frequency band showing the peak and is dispersed over a wide frequency range. In other words, if you implement a different pitch/edge arrangement on each side of the tread pattern centerline, that is, an asymmetrical arrangement, the noise will be lower than if the entire tread pattern were made into one corner, that is, a symmetrical arrangement. Well distributed.

In addition, in the arrangement shown in Fig. 4(a) and Fig. 4(c), the cost of producing the master model is relatively high in the case of tire mold manufacturing (as mentioned earlier), whereas the arrangement shown in Fig. 4( b), that is, when the B type is arranged in the opposite direction to the A type, the master mold for the A type can be used as it is for the B type, reducing costs and making mold management easier. This can be said to be a preferable method. That is, in this case, type A and type B
The tread ring (
The number of parts (casting ring for the tre/nod pattern part) will be reduced by half compared to the past.

Furthermore, the sound pressure level with respect to speed was investigated for the arrangement shown in FIG. 4(b), which is one of the embodiments of the present invention, and the arrangement shown in FIG. 4(a), which is a conventional example, and the results are shown in FIG. However, this was based on an actual vehicle coasting test at 120 km/h, and the L value was measured in the center of the vehicle interior, and the dB (A) was displayed through a bandpass filter of 100 to 2000 Hz.

〔Effect of the invention〕

The present invention exhibits the following effects.

(1) Since the pitch arrangement of the tread pattern is asymmetric on the left and right sides of the trend center line, noise can be dispersed over a wider frequency band, resulting in less noise for the human body. It has the effect of making you feel like you are being treated.

(2) By arranging the pitches on the left and right sides in the same order but in opposite directions, it is only necessary to make one mold master model, which reduces manufacturing costs.

[Brief explanation of the drawing]

Fig. 1 is a partial front view of a tread pattern that can be arranged in a pitch arrangement according to the present invention, Fig. 2 shows a pitch arrangement of a tread pattern, (, 1) is a perspective explanatory view, (b) and (C) Figure 3 is a front explanatory view of the mold seen from the inside with the mold opened.
The figure shows the pitch arrangement of the master model, Figure 4 shows the pitch arrangement of the tread pattern, (a) shows the conventional arrangement,
(b) and (C) are arrangement diagrams of the present invention, FIG. 5 is a correlation diagram between tire frequency and sound pressure level, and FIG. 6 is a correlation diagram between tire speed and sound pressure level. 1...Pattern, 2...Center line, 3...Left side, 4
...Right side, P...pitch.

Claims (1)

[Scope of Claims] 1. A pneumatic tire characterized in that the pitch arrangement of the tread pattern in the circumferential direction of the tire is asymmetrical on the left and right sides of the tire. 2. The pneumatic tire according to claim 1, wherein the asymmetry is an asymmetry in which the arrangement order is the same but the arrangement direction is reversed.