JP2011051431A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire allowing compatibly achieving of braking and driving performance and cornering performance. <P>SOLUTION: The pneumatic tire 1 includes a plurality of land part blocks 10 to 13 partitioned by peripheral direction grooves 2 to 5 and lateral grooves 6 and 7, is designated with a tire mounting direction and is set in a negative camber. Width direction step parts 20 and 30 having the same width dimensions as those of the land part blocks 10 and 11 and extending in a tread width direction are provided on at least one side of peripheral direction side edges in the land part blocks 10 and 11 arranged at the tire mounting inside. A peripheral direction step part 40 having the same length dimension as that of the land part block 12 and extending in the tire peripheral direction is provided on a side adjacent to the peripheral direction groove 2 of width direction end edges in the land part block 12 arranged at the tire mounting outside. Maximum heights of the width direction step parts 20 and 30 and the peripheral direction step part 40 are lower than heights of the land part blocks 10 to 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of achieving both on-snow performance and drainage performance.

  Conventionally, in pneumatic tires with multiple land blocks in the tread, a large number of sipes are arranged to improve the performance on snow, increasing the effect of the tread scratching snow (hereinafter referred to as the edge effect). There is something to make. However, since the rigidity of the land block decreases due to the formation of the sipe, a technique for improving the performance on snow by providing a stepped portion at the end of the land block to increase the edge effect has been developed (for example, patents) Reference 1).

JP 2007-131085 A

  However, simply providing a step on the land block makes it difficult to achieve both braking / driving performance and cornering performance on icy and snowy roads. It was required to plan.

  Accordingly, an object of the present invention is to provide a pneumatic tire capable of achieving both braking / driving performance and cornering performance on icy and snowy roads.

A first feature of the present invention is a plurality of land blocks defined by circumferential grooves (circumferential grooves 2 to 5) extending in the tire circumferential direction and lateral grooves (lateral grooves 6 and 7) extending in the tread width direction. A pneumatic tire (pneumatic tire 1) having a (land portion block 10 to 13), in which a tire mounting direction is designated and set as a negative camber, the land portion block (land At least one side of the circumferential edge of the part block 10, 11) is provided with a width step part (width step part 20, 30) having the same width as the land block and extending in the tread width direction. On the side adjacent to the circumferential groove (circumferential groove 2) in the width direction edge of the land block (land block 12) disposed on the outside, the tire circumferential direction has the same length as the land block. Extend to Provided circumferentially stepped portion (circumferential stepped portion 40), the maximum height of the widthwise stepped portion and the circumferential direction step portion is directed to subject matter is lower than the height of the land portion blocks.

  According to this feature, by providing the step portion on the land block, the edge effect is increased and the performance on snow can be improved. In addition, when the negative camber is set, the ground contact pressure is greater on the inner side of the mounting than the outer side of the mounting. Therefore, by providing a step in the width direction that extends in the tread width direction on the land block on the inner side of the mounting, The braking / driving performance can be improved. On the other hand, by providing the circumferential stepped portion extending in the circumferential direction on the outer side of the mounting, the cornering performance when the vehicle runs on an icy and snowy road is improved. Thus, according to the present invention, it is possible to achieve both braking / driving performance and cornering performance on icy and snowy roads.

  In another feature, the heights of the widthwise stepped portions (widthwise stepped portions 20 and 30) and the circumferential stepped portions (circumferential stepped portion 40) of the land portion blocks (land portion blocks 10 to 13) are set. The gist is that the height is set to 50% or more.

  The other feature is that the widthwise stepped portions (widthwise stepped portions 20 and 30) are provided at a peripheral edge on the kicking side of the land block (land blocks 10 to 13). .

  Another feature is that the widthwise stepped portions (widthwise stepped portions 20 and 30) are provided at the stepwise side circumferential edge of the land block (land block 10 to 13).

The pneumatic tire according to the present invention can achieve both braking / driving performance and cornering performance on icy and snowy roads.

It is a tread pattern which shows the land part block of the pneumatic tire by embodiment of this invention. It is sectional drawing by the AA line of FIG. It is sectional drawing by the BB line of FIG.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

  FIG. 1 is a tread pattern showing a land block of a pneumatic tire according to an embodiment of the present invention. In the present embodiment, a pneumatic tire in which a tire mounting direction is designated and set as a negative camber will be described.

  As shown in FIG. 1, the tread portion of the pneumatic tire 1 is provided with a plurality of circumferential grooves 2, 3, 4, 5 extending in the tire circumferential direction and a plurality of lateral grooves 6, 7 extending in the tread width direction. The circumferential grooves 2 to 5 and the lateral grooves 6 and 7 define a plurality of land blocks 10, 11, 12, and 13 each having a large number of sipes 8 formed on the surface.

  Of these land blocks 10 to 13, width step portions 20 and 30 extending in the tread width direction are formed on both sides of the circumferential edge of the land blocks 10 and 11 disposed on the inner side in the tire mounting direction. Has been. The width direction step portion 20 is formed by cutting out the edge portion of the side surface facing the horizontal groove 6 in the land portion block 10, and the width direction step portion 30 is formed on the side surface facing the horizontal groove 6 in the land portion block 11. The edge portion is cut out. The widthwise lengths of the widthwise stepped portions 20 and 30 are set to be the same as the width dimensions of the land blocks 10 and 11.

  On the other hand, a circumferential step 40 extending in the tire circumferential direction is formed at the inner edge in the width direction of the land block 12 arranged outside in the tire mounting direction. The circumferential step 40 is formed by cutting out the edge portion of the side surface facing the circumferential groove 2 in the land block 12. The circumferential length of the circumferential step 40 is set to be the same as the circumferential length of the land block 12.

  2 is a cross-sectional view taken along line AA in FIG.

  The width direction step part 20 mentioned above is comprised from the vertical wall surface 20a extended in a tire radial direction, and the shelf surface 20b extended in the tire circumferential direction orthogonal to this vertical wall surface 20a. Moreover, the width direction step part 30 is comprised from the vertical wall surface 30a extended in a tire radial direction, and the shelf surface 30b extended in the tire circumferential direction orthogonal to this vertical wall surface 30a. As described above, the width direction step portions 20 and 30 are provided on both the stepping side and the kicking side. The height of the land block 10, 11 that is the radial length from the groove bottom 6a to the tread surface Tr of the land block 10, 11 is H, and the height of the shelf surfaces 20b, 30b from the groove bottom 6a. Is h1. Here, the height h1 is set to 50% or more with respect to the height H, and preferably 55% or more.

  3 is a cross-sectional view taken along line BB in FIG.

  The circumferential step 40 described above is composed of a vertical wall surface 40a extending in the tire radial direction and a shelf surface 40b extending in the tire circumferential direction perpendicular to the vertical wall surface 40a. The height of the land blocks 12, 13 that is the radial length from the groove bottom 2a to the tread surface Tr of the land blocks 12, 13 is H, and the height from the groove bottom 2a to the shelf surface 40b is h2. Here, the height h2 is set to 50% or more with respect to the height H, and preferably 55% or more.

(Action / Effect)
In this embodiment, a step part is provided in the land block. For this reason, an edge effect increases and the performance on snow can be improved. When the negative camber is set, the ground contact pressure is larger on the inner side of the mounting than on the outer side of the mounting. For this reason, braking / driving performance can be improved by providing the width direction level | step-difference part extended in a tread width direction in the land part block inside mounting | wearing. On the other hand, by providing a circumferential stepped portion extending in the circumferential direction on the outer side of the mounting, cornering performance during vehicle traveling is improved. Thus, according to the present embodiment, it is possible to achieve both the braking / driving performance and the cornering performance, in particular, both the braking / driving performance and the cornering performance on an icy and snowy road surface. As shown in FIG. 1, the circumferential step 40 in the land block 12 arranged on the outer side of the mounting extends slightly inclined in the width direction with respect to the circumferential direction, so that not only cornering performance, It also contributes to starting acceleration and braking performance.

  In the present embodiment, the heights of the width direction step portions 20 and 30 and the circumferential step portion 40 are set to 50% or more with respect to the height of the land blocks 10 to 13. For this reason, the snow column effect that hardens snow when the pneumatic tire 1 contacts the ground increases, and the braking / driving performance on the icy and snowy road improves.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the said embodiment, although the width direction level | step-difference part was formed in the both sides of the circumferential direction edge in the land part block arrange | positioned inside mounting | wearing, only any one may be sufficient.

  By providing the widthwise stepped portion on the kicking side of the land block, there is an effect that the braking performance is improved when the vehicle travels on the snow surface.

  Further, by providing the width direction step portion on the stepping side of the land block, there is an effect that the traction performance is improved when the vehicle travels on the snow surface.

Next, the present invention will be described more specifically through examples.

  For Conventional Examples 1-2 and Invention Examples 1-2, a pneumatic tire having a size of 225 / 45R17 was used as a test tire. The test tires according to the conventional examples 1 and 2 are provided with neither the width-direction stepped portion nor the circumferential stepped portion described in the embodiment, and the circumferential groove and the lateral groove groove of the test tire according to the conventional example 1 The width dimension was 9.5 mm, and the groove width dimension of the circumferential groove and the lateral groove of the test tire according to Conventional Example 2 was 10.0 mm.

  Further, in the test tires according to Examples 1 and 2 of the present invention, a step portion was provided at the above-described site in FIG. The circumferential width and lateral groove width of the test tire according to Example 1 of the invention are 8.5 mm, and the circumferential width and lateral groove width of the test tire according to Example 2 of the invention are 9.0 mm. did. In Example 1 of the present invention, the height of the stepped portion was 55% of the groove depth, and in Example 2 of the present invention, the height of the stepped portion was 55% of the groove depth.

  These test tires were assembled in a test vehicle (vehicle name: Audi A3), and snow running performance, icy road running performance, dry road running performance, wet road braking performance, and wet road hydroplaning phenomenon were verified.

  The running performance on snow is a test vehicle equipped with each tire running on a test course on a snowy road surface, the steering stability in a vehicle equipped with the tire according to the conventional example 1 is set to 100, and a vehicle equipped with other tires. The steering stability was evaluated.

  As for icy road running performance, a test vehicle equipped with each tire traveled on a icy road test course, and the steering stability in a vehicle equipped with the tire according to Conventional Example 1 was set to 100, and other tires were attached. The vehicle handling stability was evaluated.

The dry road running performance is that the test vehicle on each dry tire is run on the dry road test course, the driving stability in the vehicle on which the tire according to the conventional example 1 is attached is 100, and other tires are attached. The braking performance of the wet road, which evaluated the steering stability of the vehicle, was as follows. The test vehicle equipped with each tire traveled on the wet road test course at 20 km / h, and sudden braking was applied to the vehicle equipped with the tire according to Conventional Example 1. The braking distance until the vehicle is stopped by applying 100 is taken as 100, and the braking distance of a vehicle equipped with other tires was evaluated.

The hydroplaning phenomenon on wet roads is that a test vehicle equipped with each tire runs in a pool with a water depth of 7 mm at an initial speed of 50 km / h and gradually accelerates the vehicle equipped with the tire according to Conventional Example 1. The speed at which the hydroplaning phenomenon occurred was set to 100, and the speed at which the hydroplaning phenomenon occurred in vehicles equipped with other tires was evaluated.

  As is apparent from the results in Table 1, it was found that the inventive examples 1 and 2 were better than the conventional examples 1 and 2 with good results in almost all items.

2-5 ... Circumferential groove 6 ... Horizontal groove 10-13 ... Land block 20, 30, 40 ... Stepped portion

Claims (4)

A pneumatic tire comprising a plurality of land blocks defined by a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction, the tire mounting direction being designated and set as a negative camber,
On at least one side of the circumferential edge in the land portion block arranged on the tire mounting inner side, a width direction step portion extending in the tread width direction with the same width dimension as the land portion block is provided,
On the side adjacent to the circumferential groove of the width direction edge in the land portion block arranged on the tire mounting outer side, a circumferential step portion extending in the tire circumferential direction with the same length dimension as the land block is provided,
The maximum height of the said width direction level | step-difference part and the said circumferential direction level | step-difference part is a pneumatic tire lower than the height of a land part block.   2. The pneumatic tire according to claim 1, wherein heights of the width direction step portion and the circumferential direction step portion are set to 50% or more with respect to a height of the land block.   3. The pneumatic tire according to claim 1, wherein the widthwise stepped portion is provided at a circumferential edge on a kick side in the land block.   The pneumatic tire according to any one of claims 1 to 3, wherein the step portion in the width direction is provided at a stepwise circumferential edge of the land block.

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