JP2900267B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for traveling on a road surface having a longitudinal groove
The present invention relates to a pneumatic tire for improving running stability of a vehicle.

[Conventional technology]

When traveling on a road surface that is wet due to rainfall or the like, there is a road in which vertical grooves having a constant width called a rain group are provided at a constant pitch on the road surface in order to prevent lateral slippage of tires.

Conventionally, when running on a road surface provided with the rain group, with a pneumatic tire having a tread pattern composed of blocks or ribs divided into a plurality of main grooves arranged substantially parallel along the tire circumferential direction, Alternatively, it is known that the end of the rib falls into the rain groove, thereby causing a rolling phenomenon called groove wandering. In other words, the running stability of the vehicle is hindered by the groove wonder ring,
There was a problem that the driver felt strong anxiety.

As a means for reducing such groove wandering, for example, there is a tire in which each end of a main groove in the tire circumferential direction that defines a block or a rib is set so as not to be synchronized with an end of a vertical groove of a rain groove. But,
In this tire, it is necessary to determine the position of the circumferential main groove of the tire in consideration of the position of the rain groove. Therefore, the main groove cannot be provided at an arbitrary position due to the tread design design. As a result, there is a problem that the tire performance such as steering stability and abrasion resistance is affected, and the tread pattern cannot be freely designed.

[Problems to be solved by the invention]

An object of the present invention is to reduce groove wandering when traveling on a road surface provided with a rain groove, and to determine the position of the main groove independently of the rain groove, thereby limiting the design of the tread design. An object of the present invention is to provide a pneumatic tire without any trouble.

[Means for solving the problem]

Such an object of the present invention is to provide a tire having a tread including a block defined by a plurality of main grooves arranged substantially in parallel along the tire circumferential direction and a sub-groove crossing the main groove. The block is provided with a plurality of continuous or interrupted substantially parallel thin cuts extending substantially in the circumferential direction of the tire, and the thin cuts provided on the same block are mutually substantially the same length. And at least one of the depths is different, and at least one of the substantial length and the depth is arranged so as to gradually increase from the thin cut located on the tire shoulder side to the thin cut located on the center side, and the block The pneumatic tire whose stiffness on the tire center side is smaller than that on the shoulder side, and are arranged substantially parallel along the tire circumferential direction. Tire having a tread consisting of a rib defined by a plurality of main grooves or a block defined by the main groove and a sub-groove traversing the main groove, wherein the rib or the block has a substantially tread direction. A plurality of continuous or intermittent thin cuts extending substantially parallel to each other are provided, and the depth of the thin cuts provided on the same rib or block is gradually gradually increased from the tire shoulder side toward the center side. This can be achieved by a pneumatic tire that is formed deeply and has a lower rigidity at the tire center side of the rib or block than at the shoulder side.

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

In the following embodiments, a tire having a block pattern is taken as an example. However, the present invention is not limited to this, and can be similarly applied to a tire having a rib pattern.

FIG. 1 is a partial perspective sectional view of a pneumatic tire showing one embodiment of the present invention.

As shown in the figure, the tread surface is provided with three main grooves 1 parallel to the tire circumferential direction and a number of sub-grooves 2 crossing these main grooves 1. A large number of blocks 3 defined by the main groove 1 and the sub-groove 2 are arranged in parallel along the tire circumferential direction. 5 is a breaker layer, 6 is a carcass layer, 7 is a bead, and 8 is a bead filler.

Each block 3 has a plurality of continuous or intermittent thin parallel notches 4 extending in the tire circumferential direction. Among the plurality of thin cuts 4, the cut provided at the position closest to the tire shoulder side S has the shortest length and the shortest depth. And the tire center side C
Is formed such that the length and depth of the thin notch 4 are gradually increased. That is, block 3
Are arranged such that the length and depth thereof increase in order from the tire shoulder side S to the center side C, so that each block has a thinner notch. Rigidity is shoulder side S
It is smaller than that of.

In the embodiment shown in FIG. 1, thin cuts which are sequentially different in both length and depth are provided. However, a plurality of thin cuts in the tire circumferential direction provided in the block 3 of the present invention have the same length and depth. Both need not be different, and at least one may be arranged in the order of its size. In addition,
Since the thin cut may be intermittent, the length may be substantially increased from the tire shoulder side S toward the center side C.

2 to 9 are views showing another example of a thin cut provided in the block of the tire of the present invention. 2 to 7, the plurality of thin cuts 4 provided in the block 3 each have a length and depth from the tire shredder side S of the block 3 toward the center side C. One or both of them are arranged so as to increase in order.

In the examples of FIGS. 2a, b, 3a, b, 4a, b and 5a, b, the plurality of thin cuts 4 have both length and depth from the shoulder side S to the center side. It gradually increases toward C. On the other hand, in the examples of FIGS. 6A and 7B and FIGS. 7A and 7B, the lengths of the thin cuts are all the same, but the depth is small on the shoulder side S
From the center toward the center side C.

In addition, in the examples of FIGS. 8a and 8b and FIGS. 9a and 9b, a plurality of thin cuts that are continuous or intermittent in the tire width direction and are substantially parallel to each other are provided on a block, and a plurality of thin cuts on the same block The depth of the cut is gradually increased from the tire shoulder side toward the center side, and the rigidity of each block on the tire center side is smaller than that on the shoulder side. 8a and 8b, the thin cuts 4 are discontinuous, and the depth is gradually increased from the shoulder side S to the center side C.

The shape of the thin cut in plan view does not necessarily have to be a straight line, but may be a broken line as shown in FIGS. 5a and 5b, or may be intermittent as shown in FIGS. 9a and 9b. Is also good. Alternatively, they may be inclined as shown in FIGS. 2a, b and 3a, b.

The thin cut may be formed so that both ends thereof communicate with the main groove or the sub-groove forming the block, or only one end may communicate with the main groove or the sub-groove. Further, as shown in FIGS. 4a and 5b and FIGS. 5a and 5b, both ends may not be communicated with the main groove or the sub groove.

The thickness (groove width) of the thin cut is preferably 1.5 mm or less. The depth of the thin cut is preferably such that the depth of the deepest cut on the tire center side is 0.3 to 0.8 times the depth of the main groove. However, when a thin cut is continuous with the sub-groove, it is not preferable that the depth of the thin cut be equal to or greater than the depth of the sub-groove.

Furthermore, although the number of thin cuts formed in the block is not particularly limited, it is usually preferable that the number is at least three or more.

A plurality of thin cuts having different lengths or depths provided in the block are arranged such that at least one of the length or the depth sequentially increases from the tire shoulder side S toward the center side C, or is provided in the block. The length of the plurality of thin cuts provided is the same, but by increasing the depth from the tire shoulder side S toward the center side C, the rigidity at the tire center side is made lower than that at the shoulder side, and the groove is formed. Wondering can be reduced. That is, when the tread surface is pressed against the road surface by the load and the tire bends, a lateral force is generated in the blocks and ribs, and the lateral force distribution is higher on the center side C than on the shoulder side S. Therefore, the rigidity of the blocks and ribs is
By giving directionality to the rigidity so that the rigidity becomes lower on the center side C, the blocks and the ribs are easily separated from the inside of the rain groove.

〔Example〕

Four types of radial tires having the following configurations were prepared. In each case, the tire size was the same for 195 / 60R15.

Tire of the present invention: A tire having the tread pattern of FIG. 1 comprising a plurality of blocks having thin notches shown in FIG.

However, the depth of the main groove = 8 mm, the depth of the sub groove = 7 mm, the length in the block circumferential direction = 25 mm, and the length in the block width direction = 20 mm.
Thin cuts with a length / depth of 7mm / 6mm, 6mm / 5mm, 5mm / 4mm, 4mm / 3mm are continuously made in the sub-groove at the positions where the block width is divided into five at equal intervals, in the circumferential direction of each block. A total of eight pieces were formed in each of the two pieces.

Conventional tire: As shown in FIG. 11, the same tire as the tire of the present invention except that a thin cut was not provided in the block.

Conventional tire B: As shown in FIG. 12, the same tire as the tire of the present invention except that continuous thin cuts having the same depth are also arranged in the circumferential direction of the block.

 Depth of thin notch: 4.5 mm for all, widthwise position of thin notch: same as tire of the present invention.

Comparative tire: As shown in FIG. 13, the same tire as the tire of the present invention except that the arrangement of the thin cuts was reversed.

Each of these tires is mounted on a test vehicle,
The lateral acceleration of the vehicle was detected by an accelerometer when traveling at a speed of 80 km / hr on a road surface having a rain groove with a vertical groove of 4 mm formed at a pitch of 19 mm, and the change with time was shown in a graph.

FIG. 14 is a graph showing the results of the comparative tire, FIG. 15 is a graph showing the results of the conventional tire A, FIG. 16 is a graph showing the results of the conventional tire B, and FIG. In the drawing, it is shown that the greater the change in the lateral acceleration per unit time and the fluctuation width of the lateral acceleration, the more significant the lateral rolling.

The comparison tire shown in FIG. 14 and the conventional tire A shown in FIG. 15 have substantially the same change in lateral acceleration per unit time, and the variation width of the lateral acceleration is slightly smaller in the conventional tire A. That is, it can be seen that the comparative tire and the conventional tire A show almost the same rolling. Also, the conventional tire B is slightly smaller in both the change in the lateral acceleration per unit time and the fluctuation width of the lateral acceleration as compared with the comparative tire and the conventional tire A, but the difference is small.
It shows a fairly high level of rolling. On the other hand, in the tire of the present invention, as shown in FIG. 17, both the change in the lateral acceleration per unit time and the fluctuation width of the lateral acceleration are small, and the rolling is significantly reduced.

〔The invention's effect〕

According to the present invention, in a pneumatic tire having a tread including a rib defined by a main groove arranged in parallel with the tire circumferential direction or a block defined by the main groove and the sub-groove, substantially the same block A plurality of thin cuts having different lengths or depths are arranged such that at least one of the substantial lengths or depths increases in order from a cut located on the tire shoulder side to a cut located on the center side. Alternatively, the rigidity at the tire center side was made smaller than that at the shoulder side by gradually increasing the depth of the plurality of thin cuts provided on the same rib or block from the tire shoulder side toward the center side, thereby reducing the rain. Groove wonder ring when traveling on a road with a group is reduced, Line stability is improved. Further, according to the present invention, it is possible to design without considering the position of the vertical groove of the rain group in order to reduce the groove wandering, and the tread pattern such as the position of the main groove can be freely designed, so that the steering stability and the durability can be improved. There is an advantage that tire performance such as abrasion is not sacrificed.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a cross section of an example of the tire of the present invention, and FIGS. 2a, b to 9a, b illustrate the arrangement of thin cuts provided in a block of the tire of the present invention, respectively. In each figure, a is a plan view, b is a front view, and FIGS. 10 to 13 show arrangements of thin cuts provided in blocks of a comparative tire, a conventional tire A, a conventional tire B, and a tire of the present invention, respectively. Front view, FIG. 14, FIG. 15, FIG. 16 and FIG. 17,
4 is a graph showing a rolling condition when a comparative tire, a conventional tire A, a conventional tire B, and a tire according to the present invention run on a road surface on which a rain groove is formed. 1 ... Main groove, 2 ... Sub-groove, 3 ... Block, 4 ... Thin cut.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B60C 11/12 B60C 11/06 B

Claims (2)

(57) [Claims] 1. A tire having a block defined by a plurality of main grooves arranged substantially in parallel with a tire circumferential direction and a sub-groove crossing the main groove, wherein the tire is substantially mounted on the block. A tire having a tread provided with a plurality of circumferentially extending continuous or discontinuous substantially parallel thin cuts, wherein the plurality of thin cuts provided on the same block are mutually substantially the same in length and depth. The tires of the block are arranged such that at least one of them has a different length, and at least one of the substantial length and the depth thereof sequentially increases from the thin cut located on the tire shoulder side to the thin cut located on the center side. A pneumatic tire characterized in that the rigidity on the center side is smaller than that on the shoulder side. 2. A vehicle having a rib defined by a plurality of main grooves or a block defined by said main groove and a sub-groove traversing said main groove, the rib being substantially parallel to the tire circumferential direction. A tread provided with a plurality of continuous or intermittent substantially parallel thin cuts extending substantially in the width direction of the tire on the rib or block, wherein the plurality of treads are provided on the same rib or block. A pneumatic tire characterized in that the depth of the notch is formed substantially gradually gradually from the tire shoulder side toward the center side, and the rigidity of the rib or block on the tire center side is smaller than that on the shoulder side. .