JPS61169302A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To aim at reducing noise and enhancing the comfortability provided a tire having tread design constituting elements which are arrayed at variable pitches, by specifying the ratio of a maximum design index and a minimum design index in each pitch. CONSTITUTION:Tread design constituting elements Ea each composed of a main groove 10, auxiliary grooves 20 and sipings 30 are arrayed in accordance with a variable pitch arranging method. Further, the ratio between a maximum index Gpmax and a minimum index Gpmin among design indices Gp which are expressed by the equation I relating to the tread design constituting elements Ea in pitches PA, PB, PC is set in a range from 1.05-1.30. With this arrangement, it is possible to restrain abnormal abrasion and vibration in order to enhance the effect of dispersion of noise energy, thereby it is possible to aim at reducing noise and at enhancing the comfortability.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to pneumatic tires, and more specifically, to dispersing noise (pattern noise) generated by the tread design due to tire rotation into as wide a frequency range as possible. This is a pneumatic tire that can reduce noise, and is used to improve the comfort of automobiles and suppress noise pollution.

[Conventional technology]

Conventionally, pattern noise has been dispersed using the variable pitch arrangement method, in which the design elements of the tread design are set at several different repeating pitches (fR) and arranged in an appropriately randomized order in the circumferential direction. It's here.

This is based on the frequency modulation theory used in radio engineering, etc., and is a method of changing the time interval of pulse-like vibrations generated by each design element to prevent noise from concentrating on a specific frequency. .

Furthermore, it is said that this method has a higher noise dispersion effect as the ratio α between the longest and shortest repetition pitches increases.

However, in reality, if the ratio α of the longest/shortest repeating pitch is extremely large, the shortest repeating unit becomes too small, in other words, the smallest design element becomes too small, causing abnormal wear and vibration. There is also a limit to the noise dispersion effect. (α=1.5 is the practical limit) Moreover, the market demand for noise improvement has been increasing more and more in recent years, and the current situation is that the conventional barrier pull pitch arrangement method is insufficient.

[Purpose of the invention]

The present invention was developed as a result of experiments and studies to solve the above-mentioned problems.

Therefore, an object of the present invention is to arrange the tread design using the barrier pull pitch arrangement method, and to devise the design index of each pitch element (an index determined by the volume of the main groove, auxiliary groove, and kerf and during contact with the ground). Compared to conventional tires, this product improves the dispersion effect of noise energy and reduces noise without causing abnormal wear or vibration.
An object of the present invention is to provide a pneumatic tire that can improve the comfort of an automobile and suppress noise pollution.

[Structure of the invention]

That is, the present invention is a pneumatic tire in which tread design components such as main grooves, auxiliary grooves, and sipes are arranged on the tread surface of the tire based on the barrier pull pitch arrangement method, and the tread design components in each pitch are arranged as follows: Among the design indices Gp expressed by the formula, if the ratio Gpmax/Gpn+in between the highest design index Gpa+ax and the lowest design index Qpmin is β, then the value of β is β=1.05 to 1.30. The gist is a pneumatic tire that is characterized by being set within this range.

however Suffix p: Each pitch.

i: Each groove element included in pitch p.

j: Each sipe element included in pitch p.

W: Tires are in contact with the ground under JIS standard conditions.

P: Circumferential length of pitch.

Suffix W: Width, D: Depth, L: Length.

G: Groove element.

S: Sipe element.

Gmax: Maximum main groove depth.

C. How the present invention was achieved] In the conventional barrier pull pitch arrangement method, the design elements of each pitch are designed so that the main grooves, auxiliary grooves, and sipes have approximately similar shapes, from the long pitch to the short repeat pitch. In other words, for short pitches compared to long pitches, the groove width is relatively narrowed and the length of the resize is shortened, and in the end, each pitch is The design index has almost similar values for all pitches, and the ratio β of the pitch with the highest design index and the pitch with the lowest design index is 1.0 ~
It is in the range of 1.05.

Here, the design index Gp of each pitch is defined as follows.

・・・・・・(1) however Suffix p: Each pitch -1: Each groove element included in pitch p.

j: Each sipe element included in pitch p.

W: Tires are in contact with the ground under JIS standard conditions.

P: Circumferential length of pitch.

Suffix W: Width, D = Depth, Shi = Length.

G:1! element.

S: Sipe element.

Gma: Maximum main groove depth.

The inventor of the present invention has determined that, in addition to the Valua Pulpi and Chi arrangement method, the design elements of each pitch are set so as not to be proportional to the length of the pitch, and the non-uniformity of the stiffness of each pitch is strengthened, which is effective for noise dispersion. Focusing on this fact, we conducted an experiment using the ratio β between the maximum and minimum design indices for each pitch as a parameter.

The experiment was conducted using a steel radial tire with a size of 165 SR13, fixing the longest/shortest pitch ratio α to 1.3, changing the depth, length, and width of the size at various pitches, and determining the design index of each pitch. Gp maximum/minimum ratio β
The test was carried out by changing the value from 1.0 to 1.4.

Noise measurements were carried out in accordance with JASOC606-73r Tire Noise Test Method.

As a result, it has been found that it is more advantageous for noise reduction to make the design index of each pinch non-uniform than to make it uniform, as shown in FIG.

Further, it can be seen that a clear effect is obtained when the βΦ value is 1.05 or more, and the larger the βΦ value is, the better it is.

However, if β is too large, that is, the difference between the pinch with the maximum stiffness and the one with the minimum stiffness is large,
Problems such as abnormal tire wear patterns or worsening noise during wear may occur, and β = 18 at most.
3 is the limit. Therefore, β is between 1.05 and 1.3,
It has been found that a value between 1.1 and 1.2 is preferable.

Furthermore, when creating a difference in the design index between each pitch, there are two methods: one is to increase the design index approximately in proportion to the length of the pitch, the other is to vary the design index randomly regardless of the pitch length. It has been found that the method of changing the design index only in a specific pinch is effective in both cases.

Next, in view of the fact that if the design element with the shortest pitch becomes too small, problems such as abnormal wear patterns and aggravation of noise during wear will occur, the inventor kept the design index of the minimum pitch high to increase the rigidity of the design. We continued to consider ways to increase this.

That is, an experiment was conducted in which the pitch with the minimum design index was a pitch that did not have the shortest pitch length, and rather, the shortest pitch had the highest design index.

The maximum/minimum ratio of the design index is fixed at β = 1.15,
An experiment was conducted in which the ratio β5hin of the maximum design index at pitches other than the shortest pitch and the design index at the shortest pitch was varied together with the maximum/minimum pitch length ratio α.

As a result, as shown in Figure 3, when the minimum value of the design index is given to the shortest pitch (marked O in the diagram), the thicker α is, the more the noise is reduced according to frequency modulation theory.However, α If it is 1.3 or more, the design rigidity (the element length is short and the design index is small) is low, and the noise deteriorates significantly during abnormal wear and abrasion, making it impossible to put it into practical use.

However, on the other hand, if the minimum value of the design index is given to a pitch other than the shortest pitch, and the shortest pitch is set so that the design index becomes the maximum (βllll1n smaller), α can be put to practical use up to 1.8. β5hin = 1.1
5 (marked O in the figure), β@in = 0 from α = 1.4
．． In the case of 90 (marked in the figure), α-1,8 is more effective in reducing noise.

In this way, the design index of the shortest pitch is set higher than the other maximum design index, and the maximum/minimum ratio α of the pitch length is set from a range that could not be put to practical use (β-1, 0, α=
It was found that the noise can be further reduced by increasing the value (1.5 is the limit). β-in is 0.95 or less, preferably 0.9 or less, and α is 1.3 to 1.8, preferably 1.
．． It was found that it is sufficient to set the value to 5 to 1.65.

In other words, if the stiffness of the shortest pitch is lower than before,
It was found that the upper limit of α was lower than that of the conventional method.

[Explanation of Examples]

Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings.

FIG. 1 is an explanatory plan view showing the main parts of a pneumatic tire according to an embodiment of the present invention.

In the figure, E denotes a pneumatic tire according to an embodiment of the present invention, with main grooves 10. It is constructed by arranging tread design components Ea consisting of auxiliary grooves 20 and sipes 30 based on a barrier air pull pitch arrangement method.

In the present invention, in particular, each pitch PAIP,
The ratio Gp+sax/Gpmin between the highest design index Gptaax and the lowest design index Gpmin among the design indexes Gp expressed by the formula (1) of the tread design components in P, is β
Then, the value of β is set within the range of β=1.05 to 1.30.

More specifically, FIG. 1 and Table 1 (a) below.

As shown in Table 1 (b).

(in Table 1) Gpmax = 4.42 at C Gpmin = 3.47 at A β = 4.42/3.47 = 1.27 βwin = 3.85/4.42 = 0.87 In the embodiment, when forming a tire tread design based on a variable pitch arrangement method,
By changing the design index Gp of each pitch Pm+Pl+Po and increasing the design index of the shortest pitch compared to other pitches, it is possible to increase the maximum/minimum pitch length ratio α, and it is possible to significantly reduce noise. It is possible to do so.

[Experiment example]

This experimental example is shown in FIG. 4, Table 2 (a), and Table 2 (b).

Conventional tires shown in Table 3, and Figure 1, Table 1 (a),
(in Table 1), the present invention tire (1) shown in Table 3, the present invention tire (2) shown in Table 3, the comparative example tire (1) shown in Table 3, the comparative example tire shown in Table 3 (2) was used to investigate the noise of new tires, the noise of tires after running 10,000 km, and abnormal wear.

The conventional tires are specifically as shown in FIG. 4 and Table 2 (a) and Table 2 (b) below.

As a result of the experiment, the experimental results shown in Table 3 were obtained.

Table 2 (a) Conventional pattern Table 2 (b) Gpmax=3.70 at B Gpmin=3.65 at A&C β =3.70/3.65= 1.01βwin =3
．． 70/3.65 = 1.01 From the experimental results shown on the right side of Table 3, (al) Even if α is as large as 1.63, β = 1.27 and βll1in are 0. 87, the noise resistance is improved and there are no other problems.

(bl) The tire (2) of the present invention has a thicker β of 1.19 than the conventional tire, and therefore has improved noise resistance.

(C) Comparative Example Tire (1) has problems with noise during wear and wear pattern because β is too large at 1.39.

(d+ Comparative tire (2) has β=1.0 (conventional)
In the case of 1, since α is set to a large value of 1.55, there is no improvement effect on the noise during wear, and there is a problem with the form of wear.

Note that if α exceeds 1.8, abnormal wear may occur, which is not preferable.

In the end, α is increased to a maximum of 1.8, and βmin is set to 0.
It has been found that by making β smaller than 95 and increasing β to a maximum of 1.3, it is possible to obtain a product that has the best noise properties and does not cause other problems.

〔Effect of the invention〕

Since the present invention is constructed as described above, compared to conventional tires, it is possible to enhance the noise energy dispersion effect and reduce noise without causing abnormal wear or vibration generation, thereby improving the comfort of automobiles. At the same time, noise pollution can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a plan view explanatory diagram showing the main parts of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is a diagram showing Gpmax/Gpn+i.
FIG. 3 is a diagram showing the relationship between n, that is, β, and the sound pressure level. FIG. 3 is a diagram showing the relationship between Pmax/Pa1n, that is, α, and the sound pressure level. FIG. 4 is a plan view showing the main parts of a conventional tire. It is an explanatory diagram. lO...Main groove, 20...Auxiliary groove, 30...Sipe.

Claims (1)

[Scope of Claims] A pneumatic tire in which tread design components such as main grooves, auxiliary grooves, and sipes are arranged on the tread surface of the tire based on a variable pitch arrangement method, wherein the tread design components within each pitch are as follows: Among the design indices Gp expressed by the formula, the ratio between the highest design index Gpmax and the lowest design index Gpmin Gpmax/G
A pneumatic tire characterized in that, where pmin is β, the value of β is set within the range of β=1.05 to 1.30. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, the suffix p: each pitch. i: Each groove element included in pitch p. j: Each sipe element included in pitch p. W: Tire contact width under JIS standard conditions. P: Circumferential length of pitch. Suffix w: width, D: depth, L: length. G: Groove element. S: Sipe element. Gmax: Maximum main groove depth.