JP2984086B2 - Vehicle tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle tire capable of suppressing uneven wear while reducing pattern noise.

[0002]

2. Description of the Related Art In general, the design of a tire tread is as follows.
The pattern element, which is the minimum unit of the tread design, is configured as a repeating pattern arranged side by side in the tire circumferential direction. Accordingly, in such a tire, the pulse-like vibration generated from the pattern element in accordance with the rolling of the tire is periodic, and pattern noise is likely to be generated such as the generation of compression waves in the air around the tire. This further deteriorates the noise when the resonance frequency coincides with the resonance frequency of each part of the vehicle. Therefore, conventionally, a variable pitch method in which the pitch arrangement of the pattern elements is improved has been widely adopted in order to disperse the pattern noise in a wide frequency band and reduce the noise level and prevent the resonance of the vehicle. This is a method of appropriately arranging several kinds of pattern elements having different pitch lengths in the circumferential direction of the tire to change the time interval of the pulse-like vibration so that noise is not concentrated on a specific frequency. Yes, based on frequency modulation theory.

[0003]

However, in the conventional variable pitch method, since pattern elements are generally set for the entire tread width, the effect of dispersing the frequency is limited, and the reduction of pattern noise is reduced. Was inadequate.

In order to enhance such a dispersion effect,
It can be devised to increase the number of types of pattern elements and to increase the ratio of the longest pitch length to the shortest pitch length.

However, this method greatly promotes non-uniform tread stiffness, impairs running performance, and causes a new problem that conflicts with the noise dispersing effect, such as causing uneven wear.

That is, according to the present invention, while the tread surface is divided into left and right tread areas,
On the basis of forming different tread patterns from each other by using M types and N types of pattern elements, respectively, the asymmetry of the left and right tread patterns can be greatly improved, and uneven wear and the like can be suppressed. It is an object of the present invention to provide a vehicle tire capable of enhancing a noise dispersion effect.

[0007]

In order to achieve the above object, a vehicle tire according to the present invention has a vertical groove extending in the circumferential direction of the tire at a distance of not more than 1/8 of a tread width from the tire equatorial plane. The tread surface is divided into left and right tread areas by providing, and one of the tread areas includes the longest pitch length P1M and the shortest pitch length Plm by changing the circumferential pitch lengths Pli from each other. M kinds of pattern elements Eli form a tread pattern arranged in the tire circumferential direction, and in the other tread area, the circumferential pitch length Prj is changed to be the longest pitch length PrM and the shortest. Pitch length Prm
And N kinds of pattern elements Erj including the following are formed in the tread pattern arranged in the tire circumferential direction, and the M pieces are larger than the N pieces and the pitch lengths Pli, Prj of the pattern elements Eli, Erj. On the other hand, in one tread pattern, the ratio P1M / P between the longest pitch length PIM and the shortest pitch length Plm
lm is greater than 1.10 and less than 1.36, and in the other tread pattern, the longest pitch length PrM
And the ratio PrM / Prm of the minimum pitch length Prm to 1.
The average pitch length Plo of the pattern elements Eli included in one tread area is different from the average pitch length Pro of the pattern elements Erj included in the other tread area.

[0008]

In the tire of the present invention having the above-described structure, the tread surface is divided into left and right tread areas, and tread patterns provided in the respective tread areas are formed by M kinds of pattern elements Eli having different pitch lengths from each other. And N types of pattern elements Erj.

Therefore, the pattern elements Eli, Erj
In any case, the left and right tread patterns are asymmetric, and the asymmetry is extremely high. Especially when the variable pitch method is adopted for each of the left and right tread patterns, the asymmetry is further improved, and the periodicity of the pattern as a whole tread area can be completely eliminated, thereby greatly improving the pattern noise dispersion effect. sell.

In the present invention, the ratio between the maximum pitch length and the minimum pitch length is 1.10 in each tread pattern.
Since it is regulated to the range of 1.36, the uniformity of the pattern can be improved while maintaining the dispersion effect, and the uniformity can be reduced and the occurrence of uneven wear can be suppressed.

When the average pitch length of the pattern elements in one tread area is in a range of 1.2 to 1.5 times the average pitch length of the other tread area, and the type of the pattern element in one tread area When the number is 1.2 or more and 1.5 times or less the number of the other type, the uniformity of the pattern on the entire tread surface can be further improved.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. As shown in the figure, the vehicle tire 1 has a vertical groove G extending in the circumferential direction of the tire at a distance of not more than 1/8 of the tread width WT from the tire equatorial plane CO. In this example, the tire 1 linearly extends on the tire equatorial plane CO. The tread surface S is partitioned into left and right tread regions S1 and Sr by the extending vertical groove GO, and tread patterns T1 and Tr having an asymmetric shape are formed in the left and right tread regions S1 and Sr, respectively.

Further, the one tread pattern Tl, in this example, the left tread pattern Tl, has M kinds of pitch lengths Pli different from each other in the circumferential direction, and in this example, three kinds (M
= 3) of pattern elements Eli (i = 1, 2)
... M) are arranged in the tire circumferential direction using a variable pitch method. The pattern element Eli is the minimum unit of the repeated pattern in the entire left tread region Sl, and in this example, each pattern element Eli is divided by the vertical groove G2 on the side parallel to the middle vertical groove GO. Inside, outside part Sa1, Sa
Two inner block bodies Bli arranged on the inner side Sa1
And one outer block-shaped body B2i disposed on the outer portion Sa2
And formed from

The other tread pattern Tr, in this example, the right tread pattern Tr, has N different pitch lengths Prj, and in this example, two (N = 2) types of pattern elements Erj (j = 2). .. N) are arranged by using a variable pitch method.
Similarly, in this example, each pattern element Erj is divided by a vertical groove G3 on the side parallel to the middle vertical groove GO.
It is formed from two inner block bodies Dlj disposed on the inner part Sb1 of the outer parts Sb1 and Sb2 and one outer block-shaped body D2j disposed on the outer part Sb2. In the present invention, the pitch length Pli of the left pattern element Eli is further changed to the pitch length Pli of the right pattern element Erj.
rj, and the average pitch length Plo of the pattern element Eli shown in one equation is different from the average pitch length Pro of the other pattern element Erj shown in the equation.

Plo = (El1 + El2 +... + ElM) / M Formula Pro = (Er1 + Er2 +... + ErN) / N Formula

As a result, the asymmetry of the left and right tread patterns Tl and Tr can be greatly improved without depending on the pattern arrangement and the like, and the periodicity of the pattern as a whole tread surface is reduced, that is, the tread pattern is shifted to a wide frequency band. Can promote the dispersing effect.

Further, by promoting such a dispersion effect, the number M and N of types of the pattern elements Eli and Erj in each of the tread patterns Tl and Tr can be reduced, and the ratio of the longest pitch length to the shortest pitch length can be reduced. It is possible to achieve the reduction, and to improve the uniformity and suppress the uneven wear by measuring the uniformity of the tire.

For this purpose, the left tread pattern T
The ratio P1M / Plm of the longest pitch length P1M to the shortest pitch length Plm at 1 is larger than 1.10.
It is necessary that the ratio PrM / Prm of the longest pitch length PrM to the shortest pitch length Prm in the right tread pattern Tr be smaller than 36 and larger than 1.10 and smaller than 1.36. That is, the ratio PIM / Plm,
When PrM / Prm is 1.10 or less, low noise performance cannot be maintained, for example, the effect of dispersing noise, which is an object of the present invention, is insufficient. Becomes excessive, causing uneven wear and the like.

In order to improve the uniformity over the entire tread surface of the tire 1, in this embodiment, one of the average pitch lengths Plo is used.
And the average pitch length Pro of the other, ie, Plo
/ Pro or Pro / Plo is 1.2 to 1.5, and the number M of pitch element types is 1.2 to 1.5 times N.

The ratio Plo / Pro or Pro
When / Plo is smaller than 1.2 and when the number M is smaller than 1.2N, the noise dispersion effect is reduced. Conversely, when the ratio Plo / Pro or Pro / Plo is larger than 1.5 and the number M is smaller. When it is larger than 1.5N, left and right tread patterns Tl, T
This increases the non-uniformity between the points r, causing a decrease in tire running performance and uneven wear.

As shown in the present embodiment, the left and right tread areas Sl and Sr are formed by longitudinal grooves GO extending on the tire equatorial plane CO.
Alternatively, as illustrated in FIG. 5, the tire may be defined by a vertical groove G extending in the circumferential direction of the tire at a distance L within 1/8 of the tread width WT from the equatorial plane CO of the tire. May be a zigzag groove or the like other than the linear groove.

When there are a plurality of vertical grooves G in the tread center area separated by a distance L within 1/8 of the tread width WT from the tire equatorial plane CO, the plurality of vertical grooves G can be freely selected from the plurality of vertical grooves G. By forming the tread patterns Tl and Tr having the above-described pitch arrangement in the left and right tread regions defined by the two vertical grooves G, a noise dispersion effect can be exerted.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Three types of pattern elements El1, El2, El3 having a block-like tread pattern shown in FIG. 1 and having pitch lengths P11, P12, P13 in the left tread area Sl having the relationship shown in the equation. And a tread pattern Tr composed of two types of pattern elements Er1 and Er2 having pitch lengths Pr1 and Pr2 in the right tread region Sr, respectively, having a relationship represented by the following formula.
5 tires of the present invention were prototyped, and the noise dispersion of the tire of the present invention was compared with that of a conventional tire.

Pl1 <Pl2 <Pl3 Expression Pr1 <Pr2 Expression

As shown in FIG. 2 for comparing the pattern arrangement of each tire, the conventional tire forms the same tread pattern Tl of the tire of the present invention in both the left and right tread regions. Note that the noise dispersion degree is set such that the surrounding sound microphone is placed 100 m from the center of the tire width just beside the tire.
FIG. 3A shows a frequency analysis of noise when a tire is rolled under a drum running condition with a height of 25 cm and a height of 25 cm from the ground contact surface, an internal pressure of 8.0 ksc, and a load of 2400 kgf. FIG. 3b shows the degree of dispersion of the tire of the present invention, and FIG. 3b shows the degree of dispersion of the conventional tire. FIG. 4 shows the relationship between the noise level and the tire speed when the tire is rolled under the same conditions.

[0026]

As described above, the vehicle tire of the present invention has the following features.
In each of the left and right tread regions defined by the vertical grooves, a tread pattern is formed using M types and N types of pattern elements having different pitch lengths, and the longest and shortest pattern elements disposed in each tread region are formed. Since the pitch length ratio and the like are regulated, the noise dispersing effect can be enhanced while suppressing uneven wear, and the quietness of the tire can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a tread pattern according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a tire pitch arrangement of the present invention and a conventional tire pitch arrangement used in the measurement of noise dispersion.

FIG. 3a is a diagram showing the noise variance of the tire of the invention.

FIG. 3b is a diagram showing the noise dispersion of a conventional tire.

FIG. 4 is a diagram showing a relationship between a tire speed and a noise level.

FIG. 5 is a plan view showing another embodiment of the tread pattern of the present invention.

[Explanation of symbols]

 CO Tire Equatorial plane G, GO Vertical groove S Tread surface Sl, Sr Tread area Tl, Tr Tread pattern

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-41907 (JP, A) JP-A-63-159110 (JP, A) JP-A-63-57304 (JP, A) 200006 (JP, A) JP-A-59-140104 (JP, A) JP-A-50-20402 (JP, A) JP-A-5-608 (JP, A) JP-A-1-178005 (JP, A) JP-A-4-262905 (JP, A) JP-A-4-123907 (JP, A) JP-A-60-116511 (JP, A) JP-A-2-169308 (JP, A) JP-A-62-283003 JP-A-61-16108 (JP, A) JP-A-4-201610 (JP, A) JP-A-4-103409 (JP, A) JP-A-2-237804 (JP, A) Kaihei 4-363234 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60C 11/03 B60C 11/04 B60C 11/11

Claims (4)

(57) [Claims] 1. A tread surface is divided into left and right tread areas by providing a vertical groove extending in a circumferential direction of the tire at a distance within 1/8 of a tread width from a tire equatorial plane. , Circumferential pitch length Pli
Are different from each other to form a tread pattern in which M types of pattern elements Eli including the longest pitch length P1M and the shortest pitch length Plm are arranged in the tire circumferential direction, and in the other tread area. The tread pattern in which N types of pattern elements Erj including the longest pitch length PrM and the shortest pitch length Prm are arranged in the tire circumferential direction by changing the circumferential pitch length Prj. And M is larger than N and each pattern element Eli, Erj
In one of the tread patterns, the ratio P1M / Plm of the longest pitch length P1M to the shortest pitch length Plm is larger than 1.10 and smaller than 1.36, and In the other tread pattern, the ratio PrM / Prm of the longest pitch length PrM to the minimum pitch length Prm is set to be larger than 1.10 and smaller than 1.36, and the pattern element Eli included in one tread region is further provided. Average pitch length Plo
In the other tread area
A vehicle tire different from the average pitch length Pro of rj. 2. The vehicle tire according to claim 1, wherein the longitudinal groove extends on the equatorial plane in a circumferential direction of the tire. 3. The one average pitch length Plo is 1.2 times or more and 1.5 times or less, or 1 / 1.5 times or more and 1 / 1.2 times or less of the other average pitch length Pro. The vehicle tire according to claim 1, wherein: 4. The vehicle tire according to claim 1, wherein said M number is 1.2 times or more and 1.5 times or less of said N number.