JP2010132076A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire that can effectively reduce occurrence of heel-and-toe abrasion without degrading a drainage ability. <P>SOLUTION: A center circumferential groove 2 positioned closest to a tire equatorial plane and a shoulder circumferential groove 3 positioned adjacent to the center circumferential groove 2 are arranged in a treading surface 1. A second land part 5 is sectioned between both the circumferential grooves. The second land part 5 is sectioned into block rows having a plurality of blocks by lateral grooves 12 extending in a tread width direction, at a predetermined interval in a tread circumferential direction. In a developed plane view of the treading surface, a groove center line of the shoulder circumferential groove 3 is formed in a curve. A bulging part 21 ranging from 14 to 30% of a groove depth of the center circumferential groove 2 is provided in a lateral groove of the second land part 5 throughout the length of the lateral groove. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire that can improve uneven wear resistance without impairing drainage.

  In the pneumatic radial tire, as shown in FIG. 2, for example, a center circumferential groove 42 positioned closest to the tire equatorial plane and a shoulder circumferential groove 43 positioned adjacent to the center circumferential groove 42 are formed in the tread portion. Are extended in the tread circumferential direction and arranged in a zigzag shape, and completely cross the land portions 44 and 45 defined by the circumferential grooves 42 and 43, respectively in the circumferential grooves 42 and 43. The lateral grooves 47 and 52 extending in the tread width direction are often provided, and in this type of tire, drainage in the longitudinal direction of the tire is performed by the circumferential groove, and drainage to the side of the tire is performed by the lateral groove, respectively. This makes it possible to achieve both drainage and steering stability.

  However, as shown in FIG. 2, when the circumferential groove is formed in a zigzag shape in the tire circumferential direction, the protruding corner portion of the adjacent shoulder land portion, which is partitioned by the shoulder circumferential groove, is particularly uneven. Wear easily, and in particular, by making the second land portion defined between the center circumferential groove and the shoulder circumferential groove into a block row composed of a plurality of blocks, this results in a decrease in rigidity of the block kick-out side portion. As a result, the rolling of the tire may cause heel and toe wear in which the block side of the block is worn at an early stage.

  Therefore, the present invention provides a pneumatic radial tire that can effectively reduce the occurrence of heel and toe wear without impairing drainage.

  In the pneumatic radial tire according to the present invention, a center circumferential groove positioned closest to the tire equatorial plane and a shoulder circumferential groove positioned adjacent to the center circumferential groove are disposed on the tread surface, and both of them are provided. A second land portion is partitioned between the circumferential grooves, and the second land portion is partitioned into a block row composed of a plurality of blocks by a lateral groove extending in the tread width direction at a predetermined interval in the tread circumferential direction. The groove center line of the shoulder circumferential groove is formed in a curved shape in a developed plan view of the tread surface, and the lateral groove of the second land portion has a groove depth of 14 to 30 of the center circumferential groove over its entire length. %, A raised portion having a range of% is provided.

Here, the center land portion closest to the tire equator plane is partitioned between two center circumferential grooves separated from the tire equator plane, and the center land portion is spaced in the tread circumferential direction at a predetermined interval in the tread width direction. It is defined as a block row composed of a plurality of blocks by lateral grooves extending in the direction.
The lateral groove is a groove having a longer extension length in the tread width direction than the extension length in the tread circumferential direction, and is inclined at an angle exceeding 45 ° with respect to the tread circumferential direction.
The depth of the groove is an industrial standard valid for the region where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) STANDARD MANUAL In the United States, a tire is assembled to a rim defined in TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK, etc., and the tire is filled with the highest air pressure as defined by the standards of JATMA, etc. The measured depth from the land surface.

  In such a tire, the radius of curvature of the curved portion is more preferably in the range of 50.0 to 60.0 mm with respect to the tread circumferential direction.

  Preferably, the curved portion is continuous with an inflection point provided on the groove wall in the cross section of the transverse groove.

  In the pneumatic radial tire of the present invention, by forming the center line of the shoulder circumferential groove in a curved shape in a development plan view of the tread surface, there is no corner of the protruding corner that is a source of heel and toe wear. In addition to reducing the occurrence of uneven wear on the shoulder land portion, it is possible to promote smooth water flow and improve drainage.

  In addition, by providing a raised portion in the lateral groove of the second land portion over the entire length thereof in a range of 14 to 30% of the groove depth of the center circumferential groove, the rigidity of the second land portion is improved, and the heel and toe is improved. The occurrence of wear can be suppressed.

  That is, if it is less than 14%, the effect of securing the rigidity of the second land portion may not be sufficiently obtained, and if it exceeds 30%, the rigidity balance of the entire tread pattern is lost, and the land adjacent to the second land portion is lost. There is a risk of uneven wear on the part.

  In addition, the groove center line of the shoulder circumferential groove is formed in a curved shape in a development plan view of the tread surface, and the lateral groove of the second land portion is 14 to 30% of the groove depth of the center circumferential groove over the entire length. By providing the raised portion as the range, the rigidity of the shoulder land portion, the second land portion, and the center land portion can be made uniform, and the wear balance can be made uniform.

Hereinafter, the pneumatic radial tire of the present invention will be described in detail with reference to the drawings.
Fig.1 (a) is a development top view of the tread surface which shows one Embodiment of the pneumatic radial tire of this invention, (b) is BB sectional drawing of (a), (c). FIG. 4 is a cross-sectional view taken along the line CC of FIG.
Since the reinforcing structure inside the tire is the same as that of a general radial tire, the illustration is omitted.

In the figure, 1 indicates the entire tread surface, and the tread surface 1 includes a plurality of circumferential grooves extending in the tread circumferential direction, two center circumferential grooves 2 provided with a tire equator line apart in the figure, A shoulder circumferential groove 3 adjacent to each side portion of the center circumferential groove 2 is disposed.
A center land portion 4 is defined between two circumferential grooves adjacent to each other, in the figure, between two center circumferential grooves 2, and a second land portion 5 is defined between the center circumferential groove 2 and the shoulder circumferential groove 3. Then, each shoulder land portion 6 is defined between the shoulder circumferential groove 3 and the tread side edge.

In the center land portion 4, a plurality of center blocks 8 are defined by lateral grooves 7 that extend in the tread width direction and open to the respective center circumferential grooves 2 across the center land portion 4.
The center block 8 is formed in a substantially hexagonal shape, a narrow groove 9 extending on a curve in the tread circumferential direction is disposed near the center of the block 8, and a recess 10 is formed on a wall surface adjacent to the center circumferential groove 2. And a sipe 11 that extends from the recess 10 in the tread width direction and does not open into the narrow groove 9.

In the second land portion 5, a plurality of second blocks 13 are defined by lateral grooves 12 that extend across the second land portion 5 in the tread width direction and open from the center circumferential grooves 2 to the shoulder circumferential grooves 3.
The second block 13 is formed in a substantially hexagonal shape, and a narrow groove 14 extending on a curve in the tread circumferential direction is disposed near the center of the block 13, and is adjacent to the center circumferential groove 2 and the shoulder circumferential groove 3. Recesses 15 and 16 are provided on the wall surface, and sipes 17 and 18 that extend from the recesses 15 and 16 in the tread width direction and do not open to the narrow groove 14 are provided.

  In the shoulder land portion 6, a concave portion 19 is provided in the extending direction on the outer side in the tread width direction of the lateral groove 12 provided in the second land portion 5, and a sipe 20 extending from the concave portion 19 to the outer side in the tread width direction is provided.

Further, in this pneumatic radial tire, the groove center line of the shoulder circumferential groove 3 is formed in a winding curve in the development plan view of the tread surface, and preferably the groove center line of the center circumferential groove 2 is twisted. Form a curve.
The lateral groove 12 of the second land portion 5 is provided with a raised portion 21 in the range of 14 to 30% of the groove depth H of the center circumferential groove 2 over its entire length, preferably a part of the lateral groove 7 of the center land portion 4 The raised portion 22 is provided in the range of 10 to 30% of the groove depth of the center circumferential groove.

  Here, each of the circumferential grooves 2 and 3 has, for example, a groove width of 8.0 to 14.0 mm and a groove depth of 20.0 to 26.0 mm, and the lateral grooves 7 and 12 have, for example, a groove width. Is in the range of 6.0 to 12.0 mm, the groove depth is in the range of 14.0 to 23.0 mm, and the narrow grooves 9 and 14 have, for example, a groove width of 1.0 to 2.0 mm and a groove depth of 1. It can be set as the range of 0-2.0 mm.

In this pneumatic radial tire, preferably, the radius of curvature of the curved portion of the shoulder circumferential groove 3 is formed in a range of 50.0 to 60.0 mm with respect to the tread circumferential direction, and by setting this range, It becomes a groove swing shape and becomes a shape effective for uneven wear resistance.
More preferably, the curvature radius of the curved portion of the center circumferential groove 2 is formed in the range of 35.0 to 40.0 mm.

Preferably, the curved portions of the shoulder circumferential groove 3 and the center circumferential groove 2 are continuous by providing an inflection point on the groove wall.
And preferably, the tread pattern of the pneumatic radial tire is preferably a point-symmetric pattern.

  Next, an example tire of a tire made of low fuel consumption CAP rubber having a structure as shown in FIG. 1 and a size of TBR295 / 75R22.5, and a comparative example tire as shown in FIG. As shown in FIG. 1, uneven wear resistance was evaluated by changing each specification.

  In this evaluation, each of the example tire and the comparative example tire is mounted on a rim having a rim size of 8.25 × 22.5, the internal pressure is set to 650 kPa, the load work load on the tire tread is 1900 kg. The measurement of was carried out.

  From the results of Table 2, the example tires were able to improve the uneven wear resistance of the second block compared to the comparative example tires.

(A) is a tread pattern showing one embodiment of the pneumatic radial tire of the present invention, (b) is a BB cross-sectional view of FIG. 1, and (c) is a CC cross-section of (a). FIG. It is a tread pattern which shows one embodiment of the conventional pneumatic radial tire.

Explanation of symbols

1 tread surface 2,42 center circumferential groove 3,43 shoulder circumferential groove 4,44 center land portion 5,45 second land portion 6 shoulder land portion 7, 12, 47,52 lateral groove 8 center block 9,14 narrow groove 10,15 , 16, 19 Recess 11, 17, 18, 20 Sipe 13 Second block 21, 22 Raised portion

Claims (3)

A center circumferential groove located closest to the tire equatorial plane and a shoulder circumferential groove located adjacent to the center circumferential groove are disposed on the tread surface, and a second land portion is defined between the circumferential grooves. In the pneumatic radial tire, the second land portion is divided into a block row composed of a plurality of blocks by a lateral groove extending in the tread width direction at a predetermined interval in the tread circumferential direction.
In the development plan view of the tread surface, the groove center line of the shoulder circumferential groove is formed in a curved shape,
A pneumatic radial tire characterized in that a raised portion is provided in the lateral groove of the second land portion over the entire length thereof in a range of 14 to 30% of the groove depth of the center circumferential groove.   The pneumatic radial tire according to claim 1, wherein a radius of curvature of the curved portion is formed in a range of 50.0 to 60.0 mm with respect to a tread circumferential direction.   The pneumatic radial tire according to claim 1 or 2, wherein the curved portion is continuous by providing an inflection point on a groove wall in a transverse groove cross section.

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