JP2011051425A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire compatibly achieving driving performance and braking performance. <P>SOLUTION: This pneumatic tire 1 includes a plurality of land part blocks 20 to 23 partitioned by peripheral direction grooves 2 to 5 and lateral grooves 6 to 11. Width direction step parts 40 and 50 extending in a tread width direction along a wall surface of the land part block 23 are provided on at least one side at a peripheral direction end edge in the land part block 23. A peripheral direction step part 30 for connecting the land part blocks 20 adjacent to each other in a tire peripheral direction is provided on at least one side at a peripheral direction end edge in the land part block 20. Each of the maximum heights of the width direction step parts 40 and 50 and the peripheral direction step part 30 is lower than heights of the land part blocks 20 to 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can achieve both driving performance and braking performance.

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

JP 2007-131085 A

  However, if the step portion is simply provided on the land block, the rigidity of the land block is lowered, so that the land block may fall down when the vehicle is braked and the braking performance may be lowered.

  Therefore, an object of the present invention is to provide a pneumatic tire that can achieve both driving performance and braking performance.

  The first feature of the present invention is that 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 to 11) extending in the tread width direction ( A pneumatic tire (pneumatic tire 1) including land blocks 20 to 23), wherein the land block is a plurality of first blocks (land blocks 22, 23) located on one side with respect to the tire equator line. ) And a plurality of second blocks (land blocks 20, 21) positioned on the other side with respect to the tire equator line, and at least one side of the circumferential edge of the first block includes the first block A width direction step portion (width direction step portions 40 and 50) extending in the tread width direction along the wall surface of the block is provided, and is adjacent to at least one side of the circumferential edge of the second block in the tire circumferential direction. Above A circumferential stepped portion (circumferential stepped portion 30) that connects the second blocks is provided, and the maximum height (h1, h2) of the widthwise stepped portion and the circumferential stepped portion is the height of the land block. It is summarized as being lower than (H).

  According to this characteristic, the width direction step part extended in the tread width direction along the wall surface of a land part block is provided in the both sides of the circumferential direction edge in a some land part block. According to this, the edge effect can be increased and the driving performance can be improved.

  On both sides of the circumferential edge of the plurality of land blocks, circumferential step portions that connect the land blocks adjacent in the tire circumferential direction are provided. According to this, the collapse of the land block is suppressed and the braking performance can be improved without the rigidity of the land block being excessively lowered.

  Moreover, the maximum height of the width direction step part and the circumferential step part is lower than the height of the land block. According to this, it is possible to more reliably prevent the land block from falling down and the braking performance from being lowered when the vehicle is braked without excessively reducing the rigidity of the land block. In this way, both driving performance and braking performance can be achieved.

  Another feature is that the length along the tread width direction of the step in the width direction is the same as the width along the tread width direction of the first block.

  Another feature is that the widthwise stepped portion is provided on both sides of a circumferential edge in the first block.

  In other features, the gist is that the first block is provided on the inner side when the vehicle is mounted, and the second block is provided on the outer side when the vehicle is mounted.

  Another feature is that the tire mounting direction is designated and set as a negative camber.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can aim at coexistence with drive performance and braking performance can be provided.

FIG. 1 is a tread pattern showing a land block of a pneumatic tire according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA in FIG. 3 is a cross-sectional view taken along line BB in 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.

(Composition of pneumatic tire)
First, the structure of the pneumatic tire by embodiment of this invention is demonstrated, referring drawings. 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 includes circumferential grooves 2, 3, 4, 5 extending in the tire circumferential direction and lateral grooves 6, 7, 8, 9, 10, extending in the tread width direction. 11 divides a plurality of land blocks 20, 21, 22, 23 having a large number of sipes 12 formed on the surface.

  The land blocks 20 and 21 constitute a second block located on the outer side (OUT in FIG. 1) when the vehicle is mounted with respect to the tire equator line CL. The outer land row 24 is formed on the outer side when the vehicle is mounted by the plurality of land blocks 20 along the tire circumferential direction.

  The land blocks 22 and 23 constitute a first block located on the inner side (IN in FIG. 1) when the vehicle is mounted with respect to the tire equator line CL. An inner land row 25 is formed on the inner side when the vehicle is mounted by the plurality of land blocks 23 along the tire circumferential direction.

(Configuration of circumferential step)
Next, the configuration of the circumferential step 30 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. 2 is a cross-sectional view taken along line AA in FIG.

  As shown in FIG. 1, circumferential step portions 30 that connect the land blocks 20 adjacent to each other in the tire circumferential direction are provided on both sides of circumferential edges of the plurality of land blocks 20. That is, in the outer land portion row 24, the land portion blocks 20 adjacent to each other among the plurality of land portion blocks 20 are connected by the circumferential step portion 30.

  As shown in FIG. 2, the circumferential step 30 is composed of a vertical wall surface 30a extending in the tire radial direction and a bottom surface 30b extending in the tire circumferential direction perpendicular to the vertical wall surface 30a. The height of the bottom surface 30b is formed by h1 higher than the groove bottom 7a of the lateral groove 7 indicated by a two-dot chain line. Note that the height of the land block 20 that is the length in the tire radial direction to the tread surface Tr of the land block 20 is H. Accordingly, the maximum height h1 of the circumferential step part 30 is formed lower than the height H of the tread surface Tr.

(Configuration of widthwise step)
Next, the configuration of the circumferential step 30 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 3. 3 is a cross-sectional view taken along line BB in FIG.

  As shown in FIG. 1, widthwise stepped portions 40, 50 extending in the tread width direction along the wall surface of the land block 23 are provided on both sides of the circumferential edge of the plurality of land blocks 23. That is, in the inner land portion row 25, the land portion block 23 is provided between the width direction step portions 40 and 50.

  These width direction step portions 40 and 50 are formed by cutting out edge portions on the side surfaces facing the lateral grooves 9, 10 and 11 in the land portion block 23. The length along the tread width direction of the width direction step portions 40 and 50 is the same as the width along the tread width direction of the land block 23.

As shown in FIG. 3, the width-direction stepped portion 40 is constituted by a vertical wall surface 40 a extending in the tire radial direction and a shelf surface 40 b that intersects (inclines) the vertical wall surface 40 a and extends in the tire circumferential direction. In addition, it is preferable that the length A along the tire circumferential direction of the shelf surface 40b is 7.0 mm or more.
The height of the land block 23 that is the length in the tire radial direction from the groove bottom 10a of the lateral groove 10 to the tread surface Tr of the land block 23 is H, and the height of the shelf surface 60b from the groove bottom 10a is h2. It is. Therefore, the maximum height h2 of the width direction step portions 40 and 50 is formed lower than the height H of the tread surface Tr.

(Action / Effect)
In the present embodiment, width direction step portions 40 and 50 extending in the tread width direction along the wall surface of the land portion block 23 are provided on both sides of the circumferential edge of the plurality of land portion blocks 23. According to this, the edge effect can be increased and the driving performance can be improved.

  On both sides of the circumferential edges of the plurality of land blocks 20, circumferential step portions 30 that connect the land blocks 20 adjacent to each other in the tire circumferential direction are provided. According to this, the falling of the land block 20 is suppressed and the braking performance can be improved without the rigidity of the land block 20 being excessively lowered.

  Further, the maximum heights of the width direction step portions 40 and 50 and the circumferential direction step portion 30 are lower than the heights of the land blocks 20 and 23. According to this, the rigidity of the land blocks 20, 23 is not excessively decreased, and it is possible to more reliably suppress the land blocks 20, 23 from falling down and the braking performance from being lowered when the vehicle is braked. In this way, both driving performance and braking performance can be achieved.

  In the embodiment, the length along the tread width direction of the width direction step portions 40 and 50 is the same as the width along the tread width direction of the land portion block 23. According to this, the edge effect is further increased, and the driving performance can be improved more reliably.

  In the embodiment, when the negative camber is set, the ground pressure is larger on the inner side when the vehicle is mounted than on the outer side when the vehicle is mounted. For this reason, drive performance can be improved by providing the width direction level | step-difference parts 40 and 50 extended in a tread width direction in the land part block 23 inside at the time of vehicle mounting | wearing. On the other hand, by connecting the outer land blocks 20 to each other via a circumferential step portion 30 extending in the circumferential direction when the vehicle is mounted, the rigidity of the land block 20 is improved and the collapse of the land block 20 is suppressed. Thus, the braking performance can be improved.

(Other embodiments)
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure 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, the embodiment of the present invention can be modified as follows. Specifically, the pneumatic tire 1 has been described as being set as a negative camber with a tire mounting direction designated, but is not limited to this and may be set as a positive camber. In this case, the pattern described in the embodiment is line symmetric with respect to the tire equator line CL.

  Moreover, although the width direction level | step-difference parts 40 and 50 were demonstrated as what is provided in the both sides of the circumferential direction edge in the some land part block 23, it is not limited to this, The circumference in the some land part block 23 is not limited to this. What is necessary is just to be provided in the at least one side of the direction edge.

  Moreover, although the width direction level | step-difference parts 40 and 50 were demonstrated as what is provided in the some land part block 23 located inside at the time of vehicle mounting, it is not limited to this, At least of the land part blocks 20-23 It may be provided in any one.

  Moreover, although the length along the tread width direction of the width direction level | step-difference parts 40 and 50 was demonstrated as what was the same as the width along the tread width direction of the land part block 23, it is not limited to this. The land block 23 may be shorter than the width along the tread width direction. That is, the shape of the width direction step portions 40 and 50 is not limited to that described in the embodiment, and can be appropriately set according to the purpose. For example, the shelf surface 40b may be provided orthogonal to the vertical wall surface 40a.

  Moreover, although the circumferential direction level | step-difference part 30 demonstrated as what was provided in the both sides of the circumferential direction edge in the several land part block 20, it is not limited to this, The circumferential direction end in the several land part block 20 It may be provided on at least one side of the edge.

  Moreover, although the circumferential step part 30 was demonstrated as what is provided in the several land part block 20 located outside at the time of vehicle mounting, it is not limited to this, At least any of the land part blocks 20-23 As long as it is provided.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

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

  About the conventional examples 1-2 and the example of this invention, the pneumatic tire whose size is 225 / 45R17 was made into the test tire. This test tire was assembled on a 7.5 J × 17 inch rim wheel and filled with air so that the internal pressure was 220 kPa. The vehicle used was Volkswagen's GOLF (trade name).

  In the test tire according to Conventional Example 1, only the circumferential stepped portion that connects the land blocks located outside when the vehicle is mounted is provided. In the test tire according to Conventional Example 2, only the width direction step portion is provided in the land block located on the inner side when the vehicle is mounted. In the example of the present invention, the circumferential step part 30 and the width direction step parts 40 and 50 described in the embodiment are provided.

  Vehicles equipped with these test tires were run on snowy roads, and driving performance, braking performance, and steering stability performance were verified and compared. In addition, driving on a dry road surface, the braking performance and steering stability performance were verified and compared.

  Here, in terms of driving performance, a test vehicle equipped with each tire accelerates from a stopped state to a predetermined speed (for example, 50 km / h) in a snowy road test course, and a vehicle equipped with the tire according to Conventional Example 1 The distance (driving performance) required to reach a predetermined speed was taken as 100, and the driving performance of a vehicle equipped with other tires was evaluated.

  In terms of braking performance, a test vehicle equipped with each tire travels on a snow and dry road test course at a predetermined speed (snow road; 300 km / h, dry road; 100 km / h), and the tire according to Conventional Example 1 is attached. The braking distance until the vehicle was suddenly braked and stopped (0 km / h) was taken as 100, and the braking distance of the vehicle equipped with other tires was evaluated.

  In terms of steering stability performance, a test vehicle equipped with each tire travels on a snowy road and a dry road test course, and the steering stability in a vehicle equipped with the tire according to Conventional Example 1 is set to 100, and other tires are attached. The vehicle handling stability was evaluated.

These results are shown in Table 1. In addition, each value was shown by the index evaluation which made the reference value 100.

  From these results, it was found that the test tires according to the examples of the present invention had higher overall performance than the conventional examples 1 and 2.

2-5 ... Circumferential groove 6-11 ... Transverse groove 20-23 ... Land block 30 ... Circumferential step 40, 50 ... Width step

Claims (5)

A pneumatic tire comprising a plurality of land blocks partitioned by a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction,
The land block is
A plurality of first blocks located on one side with respect to the tire equator line;
A plurality of second blocks located on the other side with respect to the tire equator line,
On at least one side of the circumferential edge in the first block, a width direction step portion extending in the tread width direction along the wall surface of the first block is provided,
At least one side of the circumferential edge in the second block is provided with a circumferential step portion that connects the second blocks adjacent to each other in the tire circumferential direction.
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 the said land part block.   The pneumatic tire according to claim 1, wherein a length along the tread width direction of the width direction step portion is the same as a width along the tread width direction of the first block.   The pneumatic tire according to claim 1 or 2, wherein the widthwise stepped portion is provided on both sides of a circumferential edge in the first block. The first block is provided on the inner side when the vehicle is mounted,
The pneumatic tire according to any one of claims 1 to 3, wherein the second block is provided outside when the vehicle is mounted.   The pneumatic tire according to any one of claims 1 to 4, wherein the tire mounting direction is designated and set to a negative camber.

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