JPH0577611A - Pneumatic tire for heavy load preventing biased abrasion - Google Patents

Abstract

PURPOSE:To restrain biased abrasion on a tread edge part by providing a recessed part to reduce bearing on the kick-out side of a land part on the side wall of the land part on the edge part of the tread in the cross direction. CONSTITUTION:A recessed part 3 to reduce bearing on a kick-out side 2b of a land part 2 is provided on the side wall of the land part 2 at the edge part of a tread T in the cross direction. At this time, the length of the recessed part 3 along circumference of a tire is expressed as A, the width of the recessed part 3 along the diametrical direction of the tire as W, the depth of the recessed part 3 along the cross direction of the tread T as S, the size of the land part along the circumference of the tire as P, the depth of a groove part 1 as D and the distance from the width edge part of the tread T to the width center of the recessed part 3 as H, and then the recessed part 3 is to satisfy conditions of A/P=0.15-0.35, H/D=0.25-1.25, W=1.5-40mm, S/D=0.15-1.5.

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 block pattern to be mounted on a vehicle such as a truck or a bus having a heavy vehicle body weight, and particularly effective for uneven wear (heel and toe wear) at the tread end of the tire. It is intended to reduce it.

[0002]

A heavy duty pneumatic tire having a block pattern having a groove portion and a land portion separated by the groove portion on the entire surface of a tread is excellent in driving and braking performance, steering stability, and wet performance. Therefore, it is used as various vehicle tires. By the way, a tire having such a block pattern has a sawtooth shape along the circumference of the tire with an increase in the traveling distance, and causes uneven wear called so-called heel and toe, which only causes deterioration of the tire performance. There was a problem that its appearance was also impaired. The above-mentioned heel and toe wear is particularly noticeable in the land portion at the widthwise end portion of the tread, which is blocked when an excessive external force (lateral force) from the road surface acts on the tread end portion of the tire during cornering. It is thought that the main reason is that the movement on the kicking side of the car is larger than that on the stepping side, and attempts have been made to reduce or improve such wear by modifying the crown shape and pattern, but it has not yet been tried. The current situation is that no appropriate preventive measures have been established.

[0003]

Uneven wear such as heel-and-toe wear in the land portion of the tread end, which was particularly remarkable in the tire having a block pattern, is reduced or reduced without adversely affecting the initial performance of the tire. It is an object of the invention to propose an improved pneumatic tire.

[0004]

According to the present invention, there is provided a heavy-load pneumatic tire having a block pattern having a groove portion and a land portion separated by the groove on the entire surface of the tread, and a land at a widthwise end portion of the tread. Is a heavy-duty pneumatic tire that prevents uneven wear, characterized in that a concave portion that reduces the surface pressure on the kicking side of the land portion is provided on the side wall of the tire portion. The length of the concave portion along the circumference is A, the width of the concave portion along the radial direction of the tire is W, the depth of the concave portion along the width direction of the tread is δ, the dimension of the land portion along the circumference of the tire is P, and the groove portion A / P = 0.15 to 0.35, H / D = 0.25 to 1.25, where D is the depth and H is the dimension from the widthwise end of the tread to the width center of the recess.
Those satisfying the conditions of W = 1.5 to 40 mm and δ / D = 0.15 to 1.5 are advantageously suitable.

1 (a) to 1 (c) show a main part of a tire according to the present invention with respect to a cross section, a plane and a side surface of a tread T in the width direction.
The groove portion 1 is a groove portion on the surface of the tire. The groove portion 1 is composed of a main groove 1a extending along the circumference of the tire and a sub groove 1b extending along the width direction of the tread T. Further, 2 is a land portion separated by a groove portion 1, 3 is a recessed portion provided on the side wall of the land portion 2 at the widthwise end of the tread, and this recessed portion 3 is a surface pressure on the kicking side of the land portion 2. Has the role of reducing

[0006]

In order to reduce the uneven wear generated in the land portion 2 at the tread end of the tire having the block pattern as shown in FIG. 2, the difference in wear between the stepping side 2a and the kicking side 2b of the land portion 2 is eliminated. It is necessary to reduce the lateral force load on the kicking side 2b of the land portion 2 at the time of cornering, that is, it is effective to reduce the ground contact pressure at that portion.

As a method of reducing the ground contact pressure, it is conceivable to reduce the radius of curvature of the tread crown. However, when such a method is applied, the tread end portion is dragged when the tire rolls, so that Uneven wear on the part (shoulder wear) cannot be avoided.

In the present invention, as shown in FIG. 1 above, a concave portion 3 is provided on the side wall of the land portion 2 at the widthwise end of the tread T to reduce the surface pressure on the kicking side 2b of the land portion 2. Therefore, the heel-and-toe wear can be effectively reduced without the above-mentioned shoulder wear.

In the present invention, the reason why A / P is regulated within the range of 0.15 to 0.35 is that the ground contact pressure of the land portion 2 on the kicking side and the wear energy of the land portion alone (ground pressure x slip amount) and A
As shown in Fig.3, if A / P is less than 0.15, the ground contact pressure on the kicking side 2b of the land portion 2 at the tread end cannot be sufficiently reduced, while if it exceeds 0.35, the ground pressure is blocked. The rigidity becomes too low, and the value of the wear energy represented by the product of the ground contact pressure and the amount of slippage becomes large, which has the disadvantage of deteriorating the tire performance, especially the wear life. Therefore, in the present invention, A / P It was limited to the range of 0.15 to 0.35. Here, the above-mentioned wear energy is an index indicating the magnitude of wear, and the larger this value is, the faster the wear is disadvantageously. Next, the reason why the H / D is regulated within the range of 0.25 to 1.25 is that the H / D is 0.25 as shown in FIG. If it is less than 1.25, the ground contact pressure on the kicking side 2a is high, which is disadvantageous in suppressing heel-and-toe wear. Therefore, in the present invention, H / D is set to 0.25 to
Limited to a range of 1.25. Next, the reason why W was set to 1.5 to 40 mm was that the reason why W was set to 1.5 or more was due to the restrictions on the production of the tires. The upper limit is as shown in FIG. This is because it is disadvantageous in reducing the ground contact pressure. Next, δ / D was set to 0.15 to 1.5 because the grounding pressure on the kicking side of the land portion 2 at the tread end and δ / D
When δ / D is less than 0.15, as shown in FIG.
This is because the effect of reducing the ground contact pressure on the kicking side of the land portion 2 is small, and when it exceeds 1.5, the land portion 2 is liable to be chipped due to the curling of the recess 3 when the tire rolls.

7 to 9 show another preferred example of the tire according to the present invention. The recess defined by the present invention may have a notched shape as shown in FIGS. 1 and 7, or as shown in FIG. 8 or an L-shape having the notched tip bent as shown in FIG. In particular, as shown in FIG. 9, when the width W of the recess is small, there is an advantage that cracks that are likely to occur at the abutting end can be effectively reduced. Further, it is most preferable to provide the concave portion 3 on the kicking side of the land portion 2, but as long as it does not adversely affect the rigidity of the land portion 2, the depression of the land portion 2 as shown in FIG. 7, FIG. 8 or FIG. It is also possible to adopt a configuration in which the side 2a is also provided. With such a configuration, it is possible to omit the complicated work of checking the kicking side and the stepping side of the land portion 2 at the time of rotation of the tire when it is not necessary to instruct the rotation direction of the tire. .

[0011]

Example: Having a tread pattern as shown in FIG.
Tires of size 10.00R20 14PR (groove depth 16.5mm) under various conditions shown in Table 1 were installed in the rim of 7.00T20, and after filling the internal pressure under the condition of pressure 8.0 kgf / cm ² , 2.D-
It was mounted on the front axle of a vehicle of type 4 and run on a 100% paved road (about 70% of a highway), and the wear condition of tires after a mileage of 50,000 km was investigated. The results are shown in Table 2.
The uneven wear area in Table 2 indicates the area of the shaded portion in FIG. 2 above, and the larger the abrasion resistance index, the better the result.

[0012]

[0013]

As is clear from Table 2, in the tire according to the present invention, the uneven wear area was significantly smaller than that of the comparative tire, and it was confirmed that the uneven wear at the tread edge is effectively reduced.

[0015]

As described above, according to the present invention, it is possible to suppress uneven wear (heel and toe wear) at the tread end portion, which was particularly remarkable in the block type pneumatic tire for heavy load, as much as possible, and to maintain the initial performance of the tire for a long time. Can be maintained over.

[Brief description of drawings]

FIG. 1A is a sectional view of a main part of a tire according to the present invention in a tread width direction, FIG. 1B is a plan view, and FIG. 1C is a side view.

FIG. 2 is a diagram showing a situation of uneven wear at a width direction end portion of a tread.

FIG. 3 is a diagram showing a relationship between ground pressure and A / P.

FIG. 4 is a diagram showing a relationship between ground pressure and H / D.

FIG. 5 is a diagram showing a relationship between a ground pressure and W.

FIG. 6 is a diagram showing the relationship between ground pressure and δ / D.

7 (a) to 7 (c) are views showing another example of the tire according to the present invention.

8 (a) to (c) are views showing another example of the tire according to the present invention.

9 (a) to 9 (c) are views showing another example of the tire according to the present invention.

FIG. 10 is a diagram showing a tread pattern.

[Explanation of symbols]

 1 Groove 2 Land 3 Recess

Claims (2)

[Claims] 1. A heavy-duty pneumatic tire having a block pattern having a groove portion and a land portion separated by the groove portion on the entire surface of the tread, wherein the land portion is provided on a side wall of the land portion at a widthwise end portion of the tread. A heavy-duty pneumatic tire that prevents uneven wear, characterized by having a recess for reducing the surface pressure on the kicking side. 2. The length of the recess along the circumference of the tire is A, the width of the recess along the radial direction of the tire is W, the depth of the recess along the width direction of the tread is δ, and the land along the circumference of the tire. Letting the size of the part be P, the depth of the groove be D, and the size from the width end of the tread to the width center of the recess being H, the above-mentioned recess has the following relation: A / P = 0.15 to 0.35 H / D = 0.25 to 1.25 The heavy duty pneumatic tire according to claim 1, which satisfies the condition of W = 1.5 to 40 mm δ / D = 0.15 to 1.5.