JPH01254406A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the braking property on snow and ice, traction property and cornering property by forming a number of dimple recessed holes on the blocks of a block pattern which is formed on a tread/and linking the dimples to block ends and between the dimples with separate calves (fine grooves). CONSTITUTION:A tread surface is formed with a block pattern consisting of zigzag main grooves 1 and lateral grooves 2 and blocks 3 formed by these grooves. A plurality of circular dimples 4 are provided on the surface of each block 3. These dimples 4 are connected to the end edges of the blocks 3 with calves 5b while also mutually linking the dimples 4, 4 together with the calves 5b. By linking at least two dimples out of a plurality of dimples with the calves, the cornering property at the time of cornering traveling can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves not only braking performance and traction performance on icy and snowy roads but also cornering performance.

[Prior art]

In general, all-weather tires and tires for icy and snowy roads have a tread surface configured with a block pattern to enhance braking and traction performance on icy and snowy roads, and the block surface also has kerfs (narrow grooves) extending in the width direction of the tire. It has been cut into. Conventionally, based on such a configuration, attempts have been made to further improve braking performance and traction performance. For example, as an attempt to do so, it has been proposed to provide dimples (concave holes) on the block surface and communicate the dimples with the inner end or middle of the kerf (Japanese Patent Laid-Open No. 61-261109). (see official bulletin).

However, there is still a demand for further improvements in braking performance and traction performance, and in particular there is a strong demand for not only braking performance and traction performance but also cornering performance to be enhanced.

[Purpose of the invention]

The purpose of the present invention is to improve braking performance and traction performance on icy and snowy roads in a tire having a block pattern.
An object of the present invention is to provide a pneumatic tire that further improves cornering performance.

[Structure of the invention]

In order to achieve the above object, the pneumatic tire of the present invention includes:
The tread surface is mainly composed of a block pattern, and a plurality of dimples are provided on the surface of the blocks forming the block pattern. Also,
The present invention is characterized in that these dimples are communicated with the edge of the block by a kerf, and at least two dimples are connected to each other by another kerf.

In the present invention, the pneumatic tire may be either a radial tire or a bias tire.

More preferably, it is applied to radial tires.

In the present invention, the block pattern refers to a tread surface in which independent ground contact portions (ridge portions) are clearly divided around the periphery by non-ground contact portions (grooves) to form a large number of blocks. This block pattern forms a column of compacted snow between adjacent blocks when driving on an icy road, and uses the shearing force of the snow column to provide better braking and traction than other tread patterns. It is now possible to demonstrate.

In the present invention, such a block pattern is mainly formed on the tread surface, but other patterns may be supplementarily added and used in combination.

That is, although this block pattern is used as the main pattern, it is also possible to use a so-called rib block pattern in which ribs extending in a band shape in the circumferential direction of the tire are used together with this block pattern.

Dimples (concave holes) provided on the block surface in the present invention
This is a space that allows the deformation of the incompressible rubber to escape when the block is deformed. That is,
The block deforms when subjected to various external forces from the road surface, but since rubber is incompressible, the block deforms with almost no change in volume. In the deformation of a block that causes almost no volumetric deformation, the spaces in the dimples create an escape area that makes it easier for the rubber to deform, and this escape of the rubber changes the block surface so that it does not separate from the road surface as much as possible. This ensures a wider contact area with the road surface. Such block deformation not only enhances braking performance and traction performance, but also enhances cornering performance against external forces from the lateral direction.

What is the shape of the above dimple in plan view? In general, it may be circular, but any other shape such as an ellipse, a triangle, a polygon such as a square, etc. can be applied.

The size of such dimples depends on the size of the tire and the size of the block, but if it is circular, the diameter is 0.
．． It is preferable that the diameter is in the range of 5 to 2.5 mm, and if it is other than circular, the diameter when converted from the cross-sectional area to a circular equivalent is in the same range as above, 0.5 to 2.5111 m.

Further, the depth of this dimple is preferably in a range of 0.6 times or more and equal to or less than the main groove adjacent to the block.

As the kerf in the present invention, a narrow groove whose width is within llllll and whose depth is 0.6 times or more and equal to or less than the leading width is preferably applied. This kerf is applied in two ways in the present invention, one of which is a kerf that allows the dimple to communicate with the outside of the side edge of the block,
The other one is a kerf for connecting at least two dimples to each other. Among these kerfs, the former kerf extends in a direction across the tire circumferential direction, that is, 1
It is preferable to provide the cuff so as to extend in the tire direction, and it is preferable that the latter cuff be arranged diagonally in the tire circumferential direction.

Further, in the present invention, the dimple and the kerf have the following relationship: dimple diameter>kerf width.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 shows an example of a block pattern (tread pattern) provided in the pneumatic tire of the present invention.
Arrow T is the tire circumferential direction. In FIG. 1, the tread surface has a plurality of main grooves 1.
..., 1 are provided in a zigzag pattern. A large number of lateral grooves 2.1 extending in the width direction of the tire are provided between adjacent main grooves 1.1. -.-92 are provided at predetermined intervals, and by providing the lateral grooves 2, a large number of blocks 3°-., 3 surrounded by the main groove 1 and the lateral groove 2 are formed.

Each block 3 has a plurality of circular dimples 4 on its surface. -94 is provided. These dimples4. - and 4 are connected to each other by a cuff 5a extending in the tire width direction, and the cuff 5a passes through the side edge of the block 3 into the lateral groove 2. Furthermore, at least two dimples 4.4 are connected to each other by another cuff 5b extending obliquely to the tire circumferential direction T.

In the tire of the present invention having the above configuration, connecting at least two of the plurality of dimples provided on the block surface with a kerf not only improves braking performance and traction performance, but also improves cornering performance during cornering. It has very important effects in improving sexual performance.

FIG. 2A shows two dimples 4.4 in the block 3 constituting the present invention, excluding the kerf 5a in the width direction of the tire.
This figure illustrates a case where only a cuff 5b connecting the two is provided. Now, assume that an external force F (lateral force) in a direction perpendicular to the tire circumferential direction T is applied to this block 3, as shown in FIG. 2B. When the block 3 is deformed by this external force F, the interface of the calf 5b is deformed while causing slippage as shown by arrows S and S, and the rubber deformation escapes into the dimple 4.4, causing deformation of compression and expansion in semicircular increments. As a result, the block as a whole changes to a shape that expands in the tire circumferential direction T.

In other words, the length of the outer edge of the block in the tire circumferential direction, that is, the length of the edge in contact with the road surface, is increased, and at the same time, the lifting of the block surface is prevented so that the contact area with the road surface is maintained as large as possible. Change. Therefore, such deformation increases the resistance against the external force F in the lateral direction, thereby improving cornering performance.

Such deformation of the block 3 also occurs when an external force is applied in the front-rear direction (traveling direction) of the tire. In other words, when an external force is applied to the block 3 in the longitudinal direction,
The length of the outer edge of the block in the tire width direction, that is, the length of the edge in contact with the road surface, changes to extend, and at the same time, the lifting of the block surface is prevented to maximize the contact area with the road surface. maintained.

Therefore, braking performance and traction performance when traveling in the tire traveling direction are also improved.

In the present invention, the connection between the dimples 4.4 by the calf 5b is not limited to only two, but also connects three, four, and five dimples as shown in FIGS. 3, 4, and 5. while,
Alternatively, more dimples may be communicated with each other.

The block 3 provided in the present invention is not only provided with a cuff 5b connecting at least two dimples as described above, but also provided with a cuff 5a in the tire width direction that extends from the dimple 4 toward the main part. do it like this. This calf 5a acts to facilitate the deformation of the rubber together with the dimples 4 when an external force is applied to the block 3, and ensures a large contact area of the block surface with the road surface, thereby improving braking performance and traction performance. strengthen.

For example, when there are two dimples 4, this calf 5a may be made as shown in Fig. 1, or as shown in Fig. 6A, for example.
It can be done as shown in FIG. 6B. Furthermore, when there are four dimples 4, in addition to the structure shown in FIG. 1, the structure shown in FIG. 7A, FIG. 7B, and FIG. 7C can be used, for example.

The effects of the present invention described above can be easily demonstrated through the following experiment.

That is, a test piece 30 of the present invention as shown in FIG. 8, which simulates the blocks of a block pattern, and a conventional test piece 300 as shown in FIG. 9 were prepared. Each specimen has a width x length x thickness of 25 x 20 x 12 mm.
The test piece 30 of the present invention has a diameter of 2
Two dimples 4.4 of ゜On+m×depth 8mm are provided, and the groove width is 0. Calf 5a of 3mm and depth 8III1w.

5b was ligated. Furthermore, the test piece 300 of the conventional example did not have the kerf 5b from the test piece 30 of the present invention.

These two types of test pieces were tested at an ice temperature of -2°C using a friction tester (manufactured by Sunny Lab) using the rotating disk method.
Temperature: -1℃, initial speed: 40km/hr, load: approximately 1kg
/cm! Under these conditions, the friction force was measured in two directions: when rotating in the A direction and when rotating in the B direction, corresponding to the tire circumferential direction and the tire width direction, respectively.

When the results were expressed as an index with the conventional example set as 100, the results were as shown in the following table.

From the results in this table, the test piece according to the present invention has improved friction force in both the tire circumferential direction (direction A) and width direction (direction B) compared to the conventional test piece. Therefore, a pneumatic tire having a block pattern based on the test piece of the present invention can further improve braking performance, traction performance, and even cornering performance compared to conventional tires.

〔Effect of the invention〕

As described above, in the pneumatic tire of the present invention, in which a block pattern is provided, a plurality of dimples are provided in the block, and these dimples are communicated with the outer edge of the block by a kerf, and at least two of the dimples are connected to the outer edge of the block by a kerf.
Since the dimples are connected to each other by separate kerfs, the block surface can be efficiently expanded and deformed relative to the road surface not only when external force is applied in the tire circumferential direction, but also when external force is applied in the tire width direction. be able to. Therefore, such deformation not only enhances braking performance and traction performance on icy and snowy roads, but also improves cornering performance even further compared to conventional tires.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a block pattern provided in the pneumatic tire of the present invention, FIG. 2A is a plan view showing a basic example of blocks in the same block pattern, and FIG. An explanatory diagram showing how it works,
3 to 5 are plan views showing basic examples of other blocks, FIGS. 6A and 6B are plan views showing an embodiment when FIG. 2A is completed as a block of the present invention, and FIG.
Figures A, B, and C are plan views showing an embodiment of the present invention when Figure 4 is completed as a block of the present invention, and Figures 8 and 9 are plan views of a test piece for a simulator. 1...Main groove, 2...Horizontal groove, 3...Block, 4...
... Dimple, 5a, 5b... Calf. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] The tread surface is mainly composed of a block pattern,
A pneumatic tire comprising a plurality of dimples provided on the surface of the blocks constituting the block pattern, these dimples communicating with the edge of the block through a kerf, and further connecting at least two dimples to each other through another kerf. .