JP3162866B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION High performance tires, i.e., pneumatic tires that have been improved to fit in service on high-end, high-performance vehicles that have improved running performance to the highest level, without sacrificing key functions. It is intended to propose a pneumatic tire that embodies a fundamental concept of a tread pattern that realizes high wet performance.

[0002]

2. Description of the Related Art A pattern in which straight ribs are arranged in a central region of a tread is generally used in order to improve stability during straight running and reduce pattern noise.

In order to improve the hydroplaning resistance of the wet performance, for example, JP-A-4-19020
It is already known that it is effective to increase the groove area (negative) as shown in the official gazette, and it is effective to increase the negative in the center area of the tread, particularly from the contact shape and distribution of the contact pressure. This is because the ground contact pressure is higher in the central region of the tread than in other regions and the ground contact length is longer during tire running.

[0004]

It is effective in terms of wet drainage to arrange a straight main groove in the center region of the tread in addition to a normal directional inclined groove, but it is effective in reducing noise and straight running stability. For the sake of simplicity, the inventors have found that by arranging ribs on both sides thereof, in this case, increasing the negative outside the ribs, the noise and the straight running stability are further improved, and the wet performance is further improved. As a result of an experimental study, the results were found. Accordingly, it is an object of the present invention to provide a pneumatic tire having a tread pattern that can advantageously improve high wet performance without sacrificing other performances.

[0005]

According to the present invention, there is provided a tread which is in contact with a road surface at a crown portion extending in a toroidal shape between a pair of sidewalls, and the tread is provided with 1 / half of a tread half width from an equatorial plane of a tire. A center circumferential groove 1 extending straight around the tread in a central area defined for both side areas outside the circumferential line extending to the center 2;
A group of oblique intermittent grooves 3 composed of a pair of oblique intermittent arrangements in which the center peripheral groove 1 is sandwiched and facing the center peripheral groove 1 so as to be convex or have a small curvature and the interval along the center peripheral groove 1 gradually changes,
A group of a large number of transverse grooves 4 and 5 which communicate with one end of each of the center inclined grooves 3 at one end and extend in a curved manner while the other end is opened at the side of the sidewall from the central area to both side areas, A tread comprising a pair of center ribs 6 divided on both sides of the circumferential groove 1 by a group of center inclined grooves 3 and a number of side lugs 7 divided by a group of center inclined grooves 3 and a group of transverse grooves 4 and 5. A pneumatic tire having a land portion, in which side lugs 7 are separated by at least one side circumferential groove 2 extending straight around the tread in both side regions near a center region. Side lugs 7 are subdivided by a sipe 8 extending along the transverse grooves 4 and 5 which divide the lugs, effectively dividing the lug width into two and reaching the center circumferential groove 1. Thing Lying, that imaginary extension of the center Hasumizo 3 and transverse grooves 4 and 5 are directional pattern by grooves sequences converging in the central circumferential groove 1 and the center Hasumizo 3
The inclinations α and β of the chords formed by line segments connecting the groove ends of the transverse grooves 4 and 5 with respect to the tire equatorial plane are 5 to 30 degrees, respectively.
Preferably, it is between 30 and 90 degrees.

FIGS. 1, 2, 3 and 4 show tread patterns based on the present invention. The basic configuration of a pneumatic tire to which these tread patterns are applied is a bead core embedded in a bead portion on the inner peripheral edge of the sidewall portion, with a pair of sidewalls and a crown portion extending in a toroidal shape therebetween. Intersection of multiple layers of mutually parallel arranged cords reinforced by a radially structured carcass consisting of a ply of cords wrapped and secured around and at a small angle around the crown, usually at a plane containing its central circumference In the arrangement of the belt to be laminated, the tread provided in the crown portion is reinforced, and furthermore, the reinforcing member can be appropriately arranged at the ply end of the bead portion or the belt end of the crown portion or the outer periphery thereof, needless to say again. Since there is no structure, illustration of the details of the structure is omitted, and only the pattern is shown in the development plane of the main part.

In each figure, 1 is a center peripheral groove, 2 is a side peripheral groove, 3 is a center inclined groove, 4 and 5 are transverse grooves, 6
Is a pair of center ribs divided by a center peripheral groove and a group of center inclined grooves 3, and 7 is a group of center inclined grooves 3 and transverse grooves 4,5.
7a and 7b are blocks formed by dividing the side lug 7 by the side circumferential groove 2. The center rib 6 and the side lugs 7 function as tread land portions.

In FIGS. 1, 2 and 4, the transverse grooves 4, 5 are:
While the center groove 3 extends from the middle point of the length of the center groove 3 to the end that opens to the side of the side wall from the start end near the center groove 1, the transverse grooves 4 and 5 are the total length of the center groove 3 in FIG. Of the center diagonal groove 3 extends in the same way from the start end of the center diagonal groove, and the center diagonal groove 3 has an intermittent arrangement in this case. Although they are not provided, they may be connected by a connecting groove.

Here, the tread T is to be provided with a road surface at a crown portion extending in a toroidal shape between a pair of sidewalls not shown in the figure, and the central area thereof is the contact width of the tread T. (Hereinafter referred to as “tread half width” and indicated by W).
2 refers to a belt-like area virtually separated by tread circumferences c and c (see FIG. 1) separating the tire from the equator to the left and right, respectively, on both sides up to the width ends e and e of the tread T on both sides. A tread T is formed with the region. The tread T has a center circumferential groove 1 extending straight around the center area thereof, and the center circumferential groove 1 is sandwiched between the center circumferential groove 1 and the interval along the center circumferential groove is gradually changed at small curvatures which are mutually convex. While the group of the center oblique grooves 3 comprising the pairs of oblique intermittent arrangements is arranged, one end of each of the center oblique grooves 3 is communicated with one end, and the other end is opened at the side of the sidewall from the central area to both side areas. A group of a large number of transverse grooves 4 and 5 extending in a curved manner is arranged. In each case in FIGS.
At least one side circumferential groove 2 extending straight around the tread 1 in both side regions adjacent to the center region of the side lug, whereby the side lug 7 is formed by the block 7a.
And 7b.

In the case of FIGS. 1 and 3, the center oblique grooves 2 sandwich the center circumferential groove 1 in a staggered arrangement with respect to each other, whereas in FIG. Be arranged. As shown in FIG. 4, the side lug 7 may be subdivided by a sipe 8 extending along the transverse grooves 4 and 5 defining the lug and dividing the lug width into two to reach the center circumferential groove 1.

In the above description, the imaginary extension of the center oblique groove 3 and the transverse grooves 4 and 5 is a directional pattern by a groove arrangement converging on the central circumferential groove 1.
Each of the transverse grooves 4 and 5 has an inclination α and β with respect to the tire equator of a string formed of a line segment connecting each groove end with 5 to 30 respectively.
{, 30 to 90}.

[0012]

In the tread pattern of a general high-performance system, that is, a pneumatic tire having a flatness of 65% or less, in order to maintain sufficient wet performance, the center circumferential groove 1 extending straight around the tread and the center circumferential groove 1 are formed. It is necessary to provide a group of center inclined grooves 3 sandwiching the same.

Since it is effective to increase the groove area especially in the center area of the tire from the grounding shape and the distribution of the grounding pressure, the group of the center circumferential groove 1 and the center inclined groove 3 is arranged in the center area of the tread T. Traverse grooves 4 and 5 extending continuously from the central region to both side regions to enable drainage in the plane of the tread T.
Is most effective. At this time, if the transverse grooves 4 and 5 are connected to the center circumferential groove 1 in the central area,
Since water flowing straight in the center circumferential groove causes turbulence due to the opening of the transverse groove, drainage is not performed efficiently,
It is necessary to separate the water channel flowing from the central region of the tread to the both side regions along the transverse grooves 4 and 5 from the center circumferential groove 1.

On the other hand, in order to secure the straight running stability particularly at the time of high-speed running, it is necessary to have a straight center rib 6 extending along the circumference of the tread T in the central region thereof.
In consideration of the wet drainage described above, the center circumferential groove 1 is arranged in the center area of the tread T, and the center ribs are arranged on both sides thereof. However, in order to secure the rigidity of the rib in the lateral direction, a circumferential groove for dividing the outside of the rib must usually be arranged at a position away from the central region of the tread T. Drainage capacity is reduced.

Therefore, by disposing the group of the oblique center grooves 3 so as to form a zigzag circumferential groove on the outer side of the ribs on both sides of the center circumferential groove 1, the rigidity of the ribs and the negativeness are ensured. It is possible to realize more efficient wettability. In particular, it is necessary to provide a center inclined groove 3 having a considerably small inclination angle in the central region of the tread T in terms of wet drainage. The center inclined groove 3 is also effective in reducing noise due to air column resonance which is a drawback of the straight main groove.

Here, the zigzag arrangement of the center inclined grooves 3 is formed by a curve having a curvature in which the angle of the tangent line to the equator direction of the tire gradually decreases toward the center circumferential groove 1, which is related to wet drainage. It matches the streamline direction of drainage to the front and side of the ground due to the rotation of the tire, and produces good results. In addition, by giving so-called directionality in which the inclination directions are opposite to each other with respect to the equatorial plane of the tire, the effect becomes more remarkable.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention was applied to a tire having specifications of a tire nominal PSR 225 / 50R16 and a tread width of 2 W: 200 mm and a contact length L of 120 mm as follows.

Invention pattern A (FIG. 1)

[Table 1]

Invention Pattern B (FIG. 2)

[Table 2]

Invention Pattern C (FIG. 3)

[Table 3]

Invention pattern D (FIG. 4)

[Table 4]

In comparison with the present invention, the conventional pattern shown in FIG. 5 is different from the present invention only in the pattern, and the other structure is the same as the inventive tire. The test results of the steering stability are shown in the following table.

[Table 5]

[0023]

According to the present invention, it is possible to significantly contribute to the improvement of wet performance under the improvement of pattern noise and dry steering stability.

[Brief description of the drawings]

FIG. 1 is a partially developed plan view of a tread pattern showing an embodiment of the present invention;

FIG. 2 is a similar plan view of another embodiment,

FIG. 3 is a similar plan view of another embodiment,

FIG. 4 is a similar plan view of a modified embodiment,

FIG. 5 is a partially developed plan view of a conventional pattern.

[Description of Signs] 1 Center peripheral groove 2 Side peripheral groove 3 Center inclined groove 4 Crossing main groove 5 Crossing main groove 6 Center rib 7 Side lug

Claims (5)

(57) [Claims] 1. A tread that is in contact with a road surface is provided on a crown portion extending in a toroidal shape between a pair of sidewalls, and a circumferential line extending from the equatorial plane of the tire to a half of a tread half width is provided on the tread. A center peripheral groove 1 extending straight around the tread in a central region defined with respect to both outer side regions, and a center having a small curvature that is convex to each other with the center peripheral groove 1 interposed therebetween. Center oblique groove 3 consisting of a pair of oblique intermittent arrangements in which the interval along peripheral groove 1 changes gradually
And a large number of transverse grooves 4 and 5 which are communicated at one end with each of the center inclined grooves 3 and extend from the central region to both side regions and bend at the side of the sidewall while the other end is open. And a pair of center ribs 6 divided on both sides of the center circumferential groove 1 by a group of center inclined grooves 3, and a group of center inclined grooves 3 and a group of transverse grooves 4, 5. A pneumatic tire having a tread land portion including a large number of side lugs 7. 2. The side lug 7 is in the form of blocks 7a, 7b separated by at least one side peripheral groove 2 extending straight around the tread in both side regions adjacent to the central region. The pneumatic tire described. 3. The side lug 7 is subdivided by a sipe 8 extending along the transverse grooves 4 and 5 defining the center lug and dividing the lug width into two parts until reaching the center circumferential groove 1. The pneumatic tire according to 1 or 2. 4. The pneumatic tire according to claim 1, wherein the imaginary extension of the center inclined groove 3 and the transverse grooves 4 and 5 is a directional pattern formed by a groove arrangement converging on the central circumferential groove 1. 5. The inclinations α and β of the chords formed of line segments connecting the ends of the center inclined groove 3 and the transverse grooves 4 and 5 with respect to the tire equatorial plane are 5 to 30 ° and 30 to 90 °, respectively. The pneumatic tire according to any one of claims 1 to 4.