JPH05147409A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve performance of a tire when the tire receives braking action and starts running by forming inclined faces on the edges on both sides of a block so as to enlarge ground contact area in the case of a tire provided with pattern having arrangement of blocks divided by peripheral directional grooves and radial directional grooves in the peripheral direction. CONSTITUTION:Inclined faces 1a are formed on both sides of the edge of each block 1 of block patterns divided by a siping so as to be brought into contact with the ground in braking and starting. At this moment, when X is taken as the overall width of the part of each block 1 to be in contact with the ground, and Y is taken as ground contact width, and theta is takes as the inclined angle of the inclined face 1a to the edge of the overall width X from the edge of the ground contact width, the equations 0.3<=(Y/X)<=0.6, and 20 deg.C<=theta<=45 deg. hold, and the overall width X shall have a width of 15% or more than the width of a block.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a pattern having a block array in the circumferential direction which is divided by circumferential grooves and radial grooves.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3A, in order to improve the performance on ice or snow, the tire has a large ground contact area and is provided with a block pattern by innumerable sipings. There is one in which the unevenness surface of the block 10 improves the ground contact property (slip resistance) to improve the braking and starting performance on ice and snow (for example, JP-A-63-103709).

[0003]

However, in the structure described above, only a part of the edge of each block 10 of the block pattern is grounded at the time of actual braking (see FIG. 3B) and starting. Because,
It was desired to improve the braking and starting performance by improving the ground contact area in each block.

Therefore, an object of the present invention is to meet the above-mentioned demand, and it is possible to further improve the grounding performance during braking and starting and to further improve the braking and starting performance. To provide.

[0005]

In order to achieve the above object, the present invention forms an inclined surface on both sides of an edge of each block of a block pattern divided by siping, and the inclined surface is provided at the time of braking and starting. The surface is grounded. That is, a pneumatic tire having a pattern having, in the circumferential direction, a block array of 3 rows to 5 rows divided by the circumferential groove and the radial groove is provided for each block divided by siping in each block pattern. When inclined surfaces are formed on both edges and the total width of the ground contact portion of each block is X and the contact width is Y, the inclination angle of the inclined surface from the edge of the contact width Y to the edge of the total width X. Let θ be 0.3 ≦ (Y
/X)≦0.6, 20 ° ≦ θ ≦ 45 °, and the total width X is 15% or more of the block width.

[0006]

According to the structure of the present invention, at the time of braking and starting, in each block, not the edge but the inclined surface can contact the grounding surface, and the grounding area at the time of braking and starting becomes large, and Since the water film can be effectively removed by forming a space between the inclined surface that is not in contact with the ground contact surface and the ground contact surface, the performance on ice and on snow can be improved.

[0007]

Embodiments of the present invention will be described in detail below with reference to FIG.

The pneumatic tire according to this embodiment is shown in FIG.
As shown in (A), a pattern having a block array of four rows divided by a circumferential groove and a radial groove in the circumferential direction is provided, and at least a small block of a shoulder block is divided into blocks 1 of each block 1. The edges on both sides except the central portion 1b are each tapered to form the inclined surfaces 1a, 1a.
Further, as a result of the formation of the inclined surfaces 1a, 1a, the total width of the ground contact portion of each block 1 divided by siping is X, the ground contact width, that is, the width of the central portion 1b is Y, and the contact width Y When the inclination angle of the inclined surface 1a from the edge to the edge of the full width X is θ,
0.3 ≦ (Y / X) ≦ 0.6 and 20 ° ≦ θ
The width X is ≦ 45 °, and the total width X is 15% or more of the block width. Where (Y
/ X) is 0.3 or more and 0.6 or less, and θ is 20 degrees or more and 45 degrees or less in Tests 1 and 2 described later.
From the result of.

In each block 1, the central portion 1b and the inclined surface 1a may be formed symmetrically with respect to the block center line 3 as shown in FIG. 1 or may be formed asymmetrically. If the blocks are too small, uneven wear is caused. Therefore, the block arrangement preferably has 3 to 5 rows, and in this arrangement, it is preferable that the tire as a whole has 30 to 70 blocks. The total width X is 1 with respect to the block width
The reason why 5% or more is preferable is that if it is less than 15%, the block rigidity decreases, braking and starting performance on dry becomes poor, and uneven wear occurs. The upper limit of the above-mentioned full width X is 0.5, and when it exceeds 0.5, uneven wear occurs.

According to the above construction, in each block 1, as shown in FIG. 1A, only the central portion 1b of the block 1 is in contact with the ground plane 2 when stopped. On the other hand, FIG. 1 (B)
As shown in (1), only one of the inclined surfaces 1a of each block 1 contacts the ground contact surface 2 during braking and starting. At this time, the inclined surface 1a of each block 1 is connected to the ground surface 2
On the other hand, they are arranged on almost one surface, and any block 1 does not protrude from the above surface. As shown in FIG. 1B, a minute space 4 is formed between the inclined surface 1a on the opposite side of the inclined surface 1a in contact with the ground surface 2 and the adjacent block 1, and the minute space 4 is formed.
As a result, the water film can be effectively removed, so that the braking performance and the starting performance can be improved.

In FIG. 4, an example of a tire having the above-mentioned structure is mounted as a vehicle on "Isuzu 810 (2-D)", the air pressure is 7.25 ksc, the load is the constant volume of the vehicle, and the rim is 7.
00Tx20, test tire 10.00R20
4P (all steel radial structure and 4 belts). Then, FIG. 4 shows tests in which the tilt angle θ was variously changed when (Y / X) = 0.3.
As the on-ice braking test, the relationship between the on-ice braking index indicating the full-lock brake braking distance at 30 Km / h and the inclination angle θ is shown in FIG. 20m as a start test on ice
FIG. 4 (B) shows the relationship between the ice start index indicating the zero start time in the section and the inclination angle θ. As a snow braking test, the relationship between the snow braking index indicating the full-lock brake braking distance at 40 km / h and the inclination angle θ is shown in FIG. 4 (C).
Shown in. Each index is a value when the 10.0R20 snow tire is 100. Further, FIG. 5 shows tests in which (Y / X) was variously changed when the inclination angle θ was 30 °. 30km as a braking test on ice
FIG. 5A shows the relationship between the above-mentioned (Y / X) and the braking index on ice indicating the full-lock brake braking distance at / h. As the ice start test, the relationship between the above-mentioned (Y / X) and the ice start index indicating the zero start time in the section of 20 m is shown in FIG. 5 (B). As a snow braking test, the snow braking index showing the full-lock brake braking distance at 40 Km / h and the above (Y / X)
The relationship with is shown in FIG. Each index is a value when the 10.0R20 snow tire is 100.

According to the above-described embodiment, the inclined surface 1 is not an edge in each block 1 during braking and starting.
a and 1a can contact the ground plane 2, the grounding area at the time of braking and starting becomes large, and the small space 4 between the inclined plane 1a not in contact with the ground plane 2 and the ground plane 2
Since the water film can be effectively removed by forming the, the performance on ice and on snow can be improved.

[Brief description of drawings]

FIG. 1 is an enlarged view of a block of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a diagram showing a braking state of a tire.

FIG. 3 is an enlarged view showing a block of a conventional pneumatic tire.

FIG. 4 is a graph showing a result of a specific test example of the tire according to the example.

FIG. 5 is a graph showing the results of other specific test examples of the tire according to the example.

[Explanation of symbols]

1 ... Block, 1a ... Inclined surface, 1b ... Central part, 2 ... Ground plane, 3 ... Center line, 4 ... Micro space.

Claims (1)

[Claims] 1. A pneumatic tire having a pattern having, in the circumferential direction, a block array of 3 rows to 5 rows divided by a circumferential groove and a radial groove, each of which is divided by siping in each block pattern. When the inclined surfaces (1a) are formed on both sides of the block (1), the total width of the ground contact portions (1a, 1b) of each block (1) is X, and the ground width (1b) is Y. ,, where θ is the inclination angle of the inclined surface (1a) from the edge of the ground contact width Y to the edge of the full width X.
3 ≦ (Y / X) ≦ 0.6 and 20 ° ≦ θ ≦ 4
It is 5 ° and the total width X is 15 with respect to the block width.
A pneumatic tire characterized by having a width of at least%.