WO2007142073A1

WO2007142073A1 - Pneumatic tire

Info

Publication number: WO2007142073A1
Application number: PCT/JP2007/060876
Authority: WO
Inventors: Akihiro Kawakita; Masahiro Katayama
Original assignee: Bridgestone Corporation
Priority date: 2006-05-29
Filing date: 2007-05-29
Publication date: 2007-12-13
Also published as: JP2007314137A

Abstract

Sipes (13) extending in the width direction (W) of a pneumatic tire are formed in each block (11) in at least one of the block rows (9) at intervals in the circumferential direction (C) of the tire. Each sipe (13) has a separated discontinuous part (13d) at at least one position. The discontinuous parts (13d) of the sipes (13) adjacent to each other in the circumferential direction (C) of the tire are displaced from each other in the width direction (W) of the tire.

Description

Specification

Pneumatic tire

Technical field

[0001] The present invention relates to a pneumatic tire such as a studless tire using a block pattern.

Background art

[0002] As a background technology of a pneumatic tire such as a studless tire, Patent Document 1 (Japanese Patent Gazette, JP 10-24707) and Patent Document 2 (Japanese Patent) are used to improve the performance on snow and snow. As disclosed in Japanese Patent Laid-Open No. 11-5415), those using a block pattern are disclosed, and pneumatic tires according to these background technologies will be described as follows.

That is, a plurality of main grooves extending in the tire circumferential direction are provided in the tread portion of the pneumatic tire. The tread portion is provided so that a plurality of lug grooves extending in the tire width direction intersect the main groove. A plurality of block rows are partitioned along the tire width direction by a plurality of main grooves and a plurality of lug grooves, and each block row also has a plurality of block forces aligned in the tire circumferential direction. Each is composed. Further, each block is formed with a plurality of sipes extending in the tire width direction so as to be arranged in the tire circumferential direction.

[0004] By the way, in order to improve the performance on ice and snow, it is necessary to increase the number of sipes and to fully exhibit the edge effect (pulling effect) by the sipes. On the other hand, when the number of sipes is increased, the rigidity of the block (the rigidity in the front-rear direction of the block) decreases and the collapse of the block increases. Therefore, the braking performance on the dry road surface or wet road surface is reduced by reducing the contact area of the block.

[0005] That is, the conventional pneumatic tire described above has a problem that it is extremely difficult to improve the braking performance on the dry road surface or the wet road surface while improving the performance on ice and snow.

[0006] The present invention has been made to solve the above-described problems, and the object of the present invention is to The object is to provide a new pneumatic tire that can suppress a decrease in rigidity in the longitudinal direction of the block even if the number of sipes is increased.

Disclosure of the invention

[0007] In order to achieve the above object, a first aspect of the present invention is a pneumatic tire including the following: a plurality of main grooves provided in the tread portion and extending in the tire circumferential direction; A plurality of lug grooves provided in the tread portion in a direction intersecting the main groove and extending in the tire width direction; and the tire width direction by the plurality of main grooves and the plurality of lug grooves A plurality of block rows that are partitioned and arranged in the tire circumferential direction, respectively, in the above configuration, in the tire width direction on the blocks in at least one block row of the plurality of block rows A plurality of extended sipes are formed at intervals in the tire circumferential direction; and each of the plurality of sipes has an interrupted portion divided at least at one location; and a tire circumference The intermittent portions of the sipes adjacent in the direction are displaced in the tire width direction.

[0008] According to the first aspect of the present invention, the plurality of sipes each have the intermittence at at least one location, and the intermittence between the sipes adjacent to each other in the tire circumferential direction. Since the position is shifted in the tire width direction, highly rigid parts can be locally dispersed in the block. As a result, even if the number of sipes is increased, a decrease in the rigidity of the block can be suppressed.

[0009] In a second aspect of the present invention dependent on the first aspect, in the pneumatic tire, the length of the intermittent portion in the tire width direction is 1. Omm or more and 5. Omm or less. .

[0010] The length of the intermittent portion in the tire width direction is set to 1. Omm or more because if the length of the intermittent portion is less than 1. Omm, the block is sufficiently rigid locally. A high part cannot be dispersed, and a force that does not sufficiently suppress a decrease in rigidity of the block is also obtained. In addition, the length of the interrupted portion in the tire width direction is set to 5. Omm or less because if the length of the interrupted portion in the tire width direction exceeds 5. Omm, the edge effect due to the sipe is more fully achieved. This is because it will not be possible to further improve the performance on ice and snow. [0011] A third aspect of the present invention dependent on the first aspect or the second aspect is that, in the pneumatic tire, the intermittent portions of the plurality of sipes are arranged in a staggered manner along a tire circumferential direction. And

[0012] According to the third aspect of the present invention, since the intermittent portions of the plurality of sipes are arranged in a staggered manner along the tire circumferential direction, a locally rigid portion in the block is provided. It can be dispersed substantially uniformly.

[0013] The fourth aspect of the present invention, which is dependent on any one of the first aspect to the third aspect, is that in the pneumatic tire, the at least one block row is the most in the tire width direction. It is an outer block row (shoulder block row).

Here, the reason why the at least one block row is the shoulder block row is that the degree of contribution of the shoulder block to the braking performance on the dry road surface or the wet road surface is large!

[0015] According to the pneumatic tire based on the first aspect to the fourth aspect of the present invention, even if the number of the sipes is increased, a decrease in rigidity of the block can be suppressed. It is possible to improve the braking performance on the dry road surface or the wet road surface by sufficiently exerting the effect and improving the performance on ice and snow while ensuring the sufficient contact area of the block.

Brief Description of Drawings

FIG. 1 (a) is a plan view of a block according to the embodiment of the present invention, and FIG. 1 (b) is a side view of the block according to the embodiment of the present invention.

FIG. 2 (a) is a plan view of a block according to another aspect of the embodiment of the present invention, and FIG. 2 (b) is a plan view of a block according to still another aspect of the embodiment of the present invention. is there.

FIG. 3 is a plan development view of a part of a tread portion in a pneumatic tire according to an embodiment of the present invention.

FIG. 4 (a) is a plan view of a block according to the first comparative example, and FIG. 4 (b) is a side view of the block according to the first comparative example.

FIG. 5 (a) is a plan view of a block according to the second comparative example, and FIG. 5 (b) is a side view of the block according to the second comparative example. [FIG. 6] FIG. 6 shows the results of a performance test.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best embodiment of the present invention will be described with reference to FIGS.

Here, FIG. 1 (a) is a plan view of a block according to the embodiment of the present invention, FIG. 1 (b) is a side view of the block according to the embodiment of the present invention, FIG. 2 (a) and FIG. FIG. 2 (b) is a plan view of a block according to another aspect of the embodiment of the present invention, and FIG. 3 is a plan development view of a part of the tread portion in the pneumatic tire according to the embodiment of the present invention.

As shown in FIG. 3, the pneumatic tire 1 according to the embodiment of the present invention is a studless tire using a block pattern, and the tread portion 3 of the pneumatic tire 1 has a tire circumference. A plurality of main grooves 5 extending in direction C are provided. The tread portion 3 is provided with a plurality of lug grooves 7 extending in the tire width direction W so as to intersect the main groove 5.

[0020] A plurality of block rows 9 are partitioned along the tire width direction W by the plurality of main grooves 5 and the plurality of lug grooves 7, and each block row 9 is arranged in the tire circumferential direction C. Each block consists of multiple blocks 11 arranged side by side. Here, in the embodiment of the present invention,

The plurality of block rows 9 are composed of a pair of block rows (center block rows) 9A on the center side in the tire width direction W and a pair of block rows (shoulder block rows) 9B on the outermost side in the tire width direction W. . The shoulder block row 9B has a large degree of contribution to the braking performance on the dry road surface or the wet road surface.

The specific configuration of the block 11 in each block row 9 is as follows.

That is, as shown in FIG. 1 (a), a plurality of sipes 13 extending zigzag in the tire width direction W are formed in the block 11 at intervals in the tire circumferential direction C. The sipe 13 extending in the tire width direction W refers to the sipe 13 extending in a direction within a range of ± 20 degrees with respect to the tire width direction W! /.

[0023] Here, the direction (implantation direction) of the plurality of sipes 13 may be the same force that is alternately different along the tire circumferential direction C. In addition, instead of the plurality of sipes 13 extending zigzag in the tire width direction W, as shown in FIG. 2 (a), the sipe 13 may extend linearly in the tire width direction W, as shown in FIG. 2 (b). As shown in Fig. It does not matter if you do. Further, as shown in FIG. 1 (b), the sipe 13 is not bent in the depth direction (left-right direction in FIG. 1 (b)), but may be bent in the depth direction. .

[0024] As shown in Fig. L (a), Fig. 2 (a) and Fig. 2 (b), each of the plurality of sipes 13 has at least one interrupted portion (divided portion) 13d. is doing. The intermittent portions 13d of the plurality of sipes 13 are staggered along the tire circumferential direction C, and the intermittent portions 13d between the sipes 13 adjacent to each other in the tire circumferential direction C are arranged in the tire width direction W. Is misaligned. In particular, in the embodiment of the present invention, the length of the intermittent portion 13d in the tire width direction W is not less than 1. Omm and not more than 5. Omm.

[0025] Next, operations and effects of the embodiment of the present invention will be described.

[0026] Each of the plurality of sipes 13 has at least one intermittent portion 13d, and the intermittent portions 13d between the sipes 13 adjacent to each other in the tire circumferential direction C are displaced in the tire width direction W and V Therefore, the block 11 can locally disperse the portion having high rigidity. Particularly, since the intermittent portions 13d of the plurality of sipes 13 are arranged in a staggered manner along the tire circumferential direction C, the block 11 has locally high rigidity, and the portions can be dispersed substantially uniformly. You can. Thereby, even if the number of sipes 13 is increased, it is possible to suppress the decrease in the Oka IJ property (the rigidity in the front-rear direction of the block 11) of the block 11.

[0027] As described above, the length of the intermittent portion 13d in the tire width direction W is set to 1. Omm or more. The length of the intermittent portion 13d is less than 1. Omm. This is because the part having sufficiently high rigidity cannot be dispersed and the decrease in rigidity of the block 11 is not sufficiently suppressed. In addition, the length of the intermittent portion 13d in the tire width direction W is set to 5. Omm or less because if the length of the intermittent portion 13d in the tire width direction W exceeds 5. Omm, the edge effect by the sipe 13 is obtained. This is because it will not be possible to fully improve the performance on ice and snow.

[0028] Therefore, according to the embodiment of the present invention, even if the number of sipes 13 is increased, the decrease in rigidity in the front-rear direction of the block 11 can be suppressed. While improving the upper performance, it is possible to sufficiently secure the contact area of the block 11 and improve the braking performance on the dry road surface or the wet road surface. [0029] The present invention is not limited to the description of the above-described embodiment. For example, a plurality of sipes 13 having intermittent portions 13d in the blocks 11 in each block row 9 are spaced in the tire circumferential direction C. It is also possible to form a plurality of sipes 13 having intermittent portions 13d only in the block 11 in the shono-redder block row 9B at intervals in the tire circumferential direction C. In addition, various embodiments can be implemented. Further, the scope of rights encompassed by the present invention is not limited to these embodiments. Example

[0030] Examples of the present invention will be described.

[0031] The pneumatic tire 1 according to the embodiment shown in Fig. 1 (a), Fig. 1 (b) and Fig. 3 is an invention, and shown in Fig. 4 (a) and Fig. 4 (b) instead of the block 11. The pneumatic tire according to the first comparative example using the block 15 is referred to as the comparative product 1, and the air according to the second comparative example using the block 17 shown in FIGS. 5 (a) and 5 (b) instead of the block 11 is used. The tire entered was made as a comparative product 2 under a tire size of 185Z70R14. The block 15 shown in FIGS. 4 (a) and 4 (b) is different from the block 11 only in that the sipe 13 does not have the intermittent portion 13d, and is shown in FIGS. 5 (a) and 5 (b). The block 17 is different from the block 11 only in that the discontinuity 13d force between the sipes 13 adjacent to each other in the tire circumferential direction C is displaced in the tire width direction W!

[0032] Then, the invented product, comparative product 1 and comparative product 2 were subjected to an on-ice acceleration performance test and a drive rake performance test, respectively, and based on the test results! Performance (brake performance on dry road)

[0033] (0 Acceleration performance test on ice

In the accelerated performance test on ice, the time required to accelerate to 30 kmZh on the test course on the ice board road surface is measured with the invention, comparative product 1 and comparative product 2 mounted on the vehicle. . As a result of the accelerated performance test on ice, the reciprocal of the measured time is summarized as an index, as shown in Table 1 below. The larger the index of ice acceleration performance evaluation, the higher the acceleration performance on ice! /

[0034] (ii) Dry brake performance test

In the dry brake performance test, the invention, comparative product 1 and comparative product 2 are used in the vehicle. With each installed, measure the time required to stop from 80kmZh on the dry road test course. As a result of the dry brake performance test, the reciprocal of the measured time is summarized as an index, as shown in Table 1 below. The higher the index of dry brake performance evaluation, the higher the dry brake performance!

That is, as shown in FIG. 6 which summarizes the results of the performance test described above, the inventive product maintains the same acceleration performance on ice and snow as the comparative product 1 and the comparative product 2, while the comparative product 1 and the comparative product. It was confirmed that the dry brake performance was improved compared to product 2.

[0036] In addition to the above, the present invention is not limited to the description of the embodiment of the invention described above, and can be implemented in various other modes by making appropriate changes.

[0037] The entire contents of Japanese Patent Application No. 2006-148740 (filed on May 29, 2006) are incorporated herein by reference.

Claims

The scope of the claims

[1] Pneumatic tires include:

A plurality of main grooves provided in the tread portion and extending in the tire circumferential direction;

A plurality of lug grooves provided in the tread portion in a direction intersecting the main groove and extending in the tire width direction; and

A plurality of block rows each formed by the plurality of main grooves and the plurality of lug grooves along the tire width direction and configured by a plurality of block forces arranged in the tire circumferential direction;

In the above configuration,

A plurality of sipes extending in the tire width direction are formed at intervals in the tire circumferential direction on the blocks in at least one of the plurality of block rows;

Each of the plurality of sipes has an interrupted portion divided into at least one part;

The intermittent portions of the sipes adjacent in the tire circumferential direction are shifted in the tire width direction.

[2] In the pneumatic tire according to claim 1,

The length of the intermittent portion in the tire width direction is 1. Omm or more and 5. Omm or less.

[3] In the pneumatic tire according to claim 2,

The intermittent portions of the plurality of sipes are arranged in a staggered manner along the tire circumferential direction.

[4] In the pneumatic tire according to claim 3,

The at least one block row force is the outermost block row in the tire width direction.