JP2005053332A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire where both ice braking performance and snow braking performance are established in a balanced manner. <P>SOLUTION: In the pneumatic tire, a plurality of vertical grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 crossing the vertical grooves 2 are disposed in a tread surface 1. A plurality of block trains circumferentially having many blocks 4 are formed of the vertical grooves 2 and lateral grooves 3, each block 4 is provided with one or more sipes 5 extending in the tire width direction, and the block 4 is partitioned to a plurality of sub-blocks 4s adjacent to each other in the tire circumferential direction. A surface of the sub-blocks 4s of the block 4 in at least one block train is formed on a recessed circular arc surface in the tire radial direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which both on-ice braking performance and on-snow braking performance are balanced.

  The winter pneumatic tire is provided with a plurality of vertical grooves extending in the tire circumferential direction and a plurality of horizontal grooves extending in the tire width direction on the tread surface in order to ensure braking / driving performance on a snowy road surface. Thus, a tread pattern in which a plurality of block rows are partitioned is employed. Furthermore, in order to ensure braking / driving performance on the road surface on ice, a notch called a sipe extending in the tire width direction is provided on the surface of each block, and the grounding property is improved by reducing the rigidity of the tread portion, and the capillary phenomenon and The edge effect by water film destruction is improved.

  Conventionally, the surface of each block partitioned by the tread surface has usually been formed as a convex curved surface having a single radius of curvature that forms the outer contour of the tread surface, and therefore there is a limit to the edge effect obtained by forming the sipe. there were.

As an improvement measure against such a limit, the surface of the small block divided by the sipe formed on the block is protruded from the outer contour surface of the tread surface to prevent the small block from collapsing when braking on the road surface on ice. There is a proposal to secure an area and thereby improve the performance on ice (see Patent Document 1). However, in this proposal, the edge effect at the time of braking on a snowy road surface cannot be sufficiently obtained, and there is a problem that the braking performance on snow is reduced.
Japanese Patent Application Laid-Open No. 10-244813

  An object of the present invention is to provide a pneumatic tire that solves the conventional problems and balances braking performance on ice and braking performance on snow in a well-balanced manner.

  In order to achieve the above object, the pneumatic tire of the present invention is provided with a plurality of longitudinal grooves extending in the tire circumferential direction on the tread surface and a plurality of lateral grooves intersecting the longitudinal grooves, and the circumferential grooves and the lateral grooves are used to surround the pneumatic tire. A plurality of block rows in which a number of blocks are arranged in the direction, and at least one sipe extending in the tire width direction is provided in each block, and the block is divided into a plurality of sub-blocks adjacent in the tire circumferential direction In the entering tire, the surface of the sub block in the block of at least one block row is formed in a concave arc surface in the tire radial direction.

  In the pneumatic tire of the present invention, at least one sipe extending in the tire width direction is provided in each block of at least one block row, and the block is divided into a plurality of sub-blocks adjacent in the tire circumferential direction. Since the surface of the block is formed as a concave arc surface in the tire radial direction, each block surface has a plurality of sub-block edges protruding in the tire radial direction corresponding to the number of sipes in the tire width direction. Since the portions are intermittently arranged in the tire circumferential direction, the edge effect is exhibited during braking on ice and on snow, and both ice braking performance and snow braking performance can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a partial plan view showing an example of a tread surface of the pneumatic tire of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG.

  The tread surface 1 of the pneumatic tire is provided with a plurality of longitudinal grooves 2 extending in the tire circumferential direction T and a plurality of transverse grooves 3 intersecting with the plurality of longitudinal grooves 2. A plurality of (5 in the figure) block rows 4a, 4b, 4c, 4d, and 4e in which the blocks 4 are arranged are partitioned. Each block 4 of each block row 4a, 4b, 4c, 4d, 4e is formed with one or more sipes 5 extending in the tire width direction.

  As shown in FIG. 2, each block 4 in each block row 4a, 4b, 4c, 4d, 4e is partitioned into a plurality of sub-blocks 4s by a sipe 5 opening in the main groove 2. The surface of the sub block 4s is formed in an arc surface having a concave curvature radius Ra in the tire radial direction. Therefore, the concave radius of curvature Ra is in a reverse R relationship with the radius of curvature Rd formed by the outer contour line Q of the tread surface 1, whereby the surface of the block 4 has a number of sub-blocks 4 s from the tread surface 1. The edge portion of the projection is formed to protrude.

  The concave curvature radius Ra is preferably 0.1 times or more the curvature radius Rd formed by the outer contour line Q of the tread surface 1. If the curvature radius Ra is less than 0.1 times the curvature radius Rd, the edge effect on the road surface on ice is insufficient. The upper limit of the ratio of the curvature radius Ra to the curvature radius Rd is preferably 5.0 times or less, and most preferably 3.0 times or less.

  In this way, by making the curvature radius Ra of the sub-block 4s inversely R with the curvature radius Rd of the outer contour line Q of the tread surface 1, the edge portion of the sub-block 4s protrudes from the surface of the block 4, and is Improve braking and driving performance by enhancing the edge effect on the road surface on snow.

  When the surface of the sub-block 4s described above is formed in a concave arcuate surface, the surface of the sub-block 4s is formed in a concave arcuate surface for all blocks in the block rows 4a, 4b, 4c, 4d, and 4e. Although it is most preferable, it does not preclude application to a block of at least one block column in each block column. Moreover, it is not necessary to apply to all the blocks constituting one block row. Moreover, the sipe 5 that divides the sub-block 4s may be a zigzag sipe extending in the width direction of the block 4 or may include a sipe that does not penetrate in the width direction of the block 4. Further, the pattern configuration of the tread surface 1 is not limited to the embodiment of FIG.

  In the pneumatic tire 1 of the present invention described above, one or more sipes 5 extending in the tire width direction are provided in each block 4 of at least one block row, and the plurality of sub-blocks 4s adjacent to the block 4 in the tire circumferential direction are provided. In addition, the surface of the sub-block 4s is formed in a concave arc surface in the tire radial direction, and the edge of the sub-block 4s is formed on the surface of each block 4 to improve the braking / driving performance. It is preferably applied to winter tires because it exhibits an edge effect when braking on ice and snowy road surfaces.

  The tire radius is 175 / 80R14 (curvature radius Rd = 636 mm) and the tread pattern is the same as in FIG. 1, and the curvature radius Ra of the surface of the sub-block 4s of each block in the block rows 4b, 4c and 4d is shown in Table 1. The conventional tires (conventional examples), the tires of the present invention (Examples 1 to 5), and the comparative tires (Comparative Examples 1 and 2) were produced. In Table 1, when the radius of curvature Ra is a negative numerical value, it indicates that the surface of the sub-block 4s is formed in an arc that is convex in the radial direction.

For these eight types of tires, the braking performance on ice and the braking performance on snow were evaluated by the following methods, and the results are shown in Table 1 by index display where the conventional example is 100. The larger the value, the better.
[Evaluation of braking performance on ice]
Each tire was mounted on a domestic 2.0L class vehicle, the braking distance was measured by lock braking at a braking speed of 40 km / h on the road surface on ice, and evaluation was made based on the result.
[Snow braking performance evaluation]
Similarly to the above, each tire was mounted on a domestic 2.0L class vehicle, and the braking distance was measured by lock braking at a braking speed of 40 km / h on the road surface on snow.

表１から、本発明タイヤは、サブブロック４ｓの表面がトレッド面１の外輪郭線の曲率半径と同等に形成された従来タイヤに比較して、氷上制動性能及び雪上制動性能がバランス良く両立していることがわかる。

From Table 1, the tire of the present invention has a good balance between the braking performance on ice and the braking performance on snow as compared with the conventional tire in which the surface of the sub-block 4s is formed to be equal to the radius of curvature of the outer contour line of the tread surface 1. You can see that

It is a partial top view which shows an example of the tread surface of the pneumatic radial tire of this invention. It is AA arrow sectional drawing of FIG.

Explanation of symbols

1 Tread surface 2 Vertical groove 3 Horizontal groove 4 Block 4s Sub block 5 Sipe

Claims (2)

A plurality of vertical grooves extending in the tire circumferential direction and a plurality of horizontal grooves intersecting the vertical grooves are provided on the tread surface, and a plurality of block rows in which a large number of blocks are arranged in the circumferential direction are formed by the vertical grooves and the horizontal grooves. In addition, in the pneumatic tire in which each block is provided with one or more sipes extending in the tire width direction and the block is divided into a plurality of sub-blocks adjacent in the tire circumferential direction,
A pneumatic tire in which a surface of the sub block in at least one block row block is formed in a concave arc surface in a tire radial direction. The pneumatic tire according to claim 1, wherein a radius of curvature of the concave arc surface is 0.1 to 5.0 times a radius of curvature of an outer contour line of the tread surface.

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