JPH06143941A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire for maintaining the traveling performance on ice while improving uneven wear property and cornering performance on a dry road surface. CONSTITUTION:A tread surface is formed with a plurality of blocks 3 divided by grooves. At least a calf extending widthwise of a tire is provided respectively on the surfaces of these blocks. The calf 4 is formed on the surface of the block 3 in the corrugated form as viewed in a plan and side elevation. The calf 4 is corrugated in the section of the tangential direction A and normal direction B and the corrugated portions mesh with each other.

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 such as a studless tire and an all-season tire, and particularly, while maintaining the running performance on ice,
The present invention relates to a pneumatic tire having improved uneven wear resistance and cornering performance on a dry road surface.

[0002]

2. Description of the Related Art Conventionally, in pneumatic tires such as studless tires and all-season tires, a plurality of blocks divided by relatively deep grooves are formed on the tread surface, and the blocks extend in the tire width direction. The mainstream is one in which at least one kerf (cut) is provided to improve the running performance on ice by the edge effect of this kerf.

FIG. 4 shows a tire circumferential direction cross section of a block formed on the tread surface of such a studless tire or an all-season tire. The surface of the block 11 is provided with a kerf 12 which is linear in the normal direction of the surface of the block 11 and extends in the tire width direction in order to improve the exercise performance on the ice. It is divided into blocks 11a.

[0004]

However, since the block 11 is subdivided by the kerf 12 to reduce the rigidity, and the kerf 12 is formed in a straight line in the direction normal to the surface of the block 11. When traveling on a dry road surface which is not covered with snow or ice, the sub-block 11a falls in the direction opposite to the traveling direction F as shown in FIG. Since it becomes uneven, heel and toe wear is likely to occur.

Further, since the block 11 having the reduced rigidity is easily deformed by the lateral force during cornering, there is a problem that the cornering performance on a dry road surface is also deteriorated. To solve these problems,
It is necessary to maintain the rigidity of the block 11 and reduce the amount of deformation, but as a means for maintaining the rigidity of the block 11, if the block pattern is changed or the groove on the tread surface is formed shallowly, it is originally required. It will be difficult to maintain good running performance on ice. The purpose of the present invention is to
It is an object of the present invention to provide a pneumatic tire capable of improving uneven wear resistance and cornering performance on a dry road surface while maintaining the running performance on ice.

[0006]

A pneumatic tire of the present invention for achieving the above-mentioned object forms a plurality of blocks divided by grooves on a tread surface, and each of the plurality of blocks has a surface in the tire width direction. In a pneumatic tire provided with at least one kerf extending, the kerf is formed in a corrugated shape in both the plan view and the side view of the block.

As described above, the kerf formed in a wavy shape in both the plan view and the side view of the block has a wavy shape in both the tangential direction cross section and the normal direction cross section,
Because the corrugated parts mesh with each other,
Each of the sub-blocks divided by the kerf regulates the collapse of each other with respect to both the front-back bending and the left-right bending to reduce the deformation amount of the block. Therefore, even when traveling on a dry road surface that is not covered with snow or ice and has a high friction coefficient, uneven distribution of the contact pressure during braking is reduced, so that uneven wear such as heel and toe wear is effectively suppressed. You can
The steering stability during cornering can be improved.

Further, in the present invention, it is not necessary to change the block pattern and it is not necessary to form the groove on the tread surface shallow in order to reduce the deformation amount of the block.
It is possible to maintain a predetermined running performance on ice. Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a plan view showing an example of a tread pattern of a pneumatic tire of the present invention. In FIG. 1, the tread surface T is provided with a plurality of main grooves 1 and quasi-main grooves 1a extending in the tire circumferential direction, and a plurality of sub-grooves 2 and quasi-sub grooves 2a extending in the tire width direction. As a result, a plurality of blocks 3 having different shapes are divided and formed. All of the blocks 3 are provided with at least one kerf 4 extending in the tire width direction on the surface thereof, whereby each block 3 is divided into a plurality of sub-blocks 3a. The calf 4 formed on the block 3
The shape of the kerf 4 is a wave shape as described below, but in FIG. 1, the shape of the kerf 4 is simply shown by a straight line.

FIG. 2 is an enlarged perspective view showing a part of the block 3 described above. As shown in FIG. 2, in the block 3, the kerf 4 is formed in a wavy shape that is inclined and oriented with respect to the tangential direction A and the normal direction B of the block surface. That is, the kerf 4 has a tangential direction A of the block 3.
Both of the cross sections (side view) and the normal direction B (plan view) have a corrugated shape, and the corrugated portions mesh with each other.

In the present invention, when traveling on a dry road surface, even if the block 3 bends in the front-back direction during driving or braking during straight running, or in the left-right direction during cornering, the corrugated portions of the kerfs 4 mesh with each other. Since the plurality of sub-blocks 3a regulate the collapse of each other, the deformation amount of the block 3 is reduced. That is, during braking, the sub-blocks 3a behave as shown in FIG. 3 and mesh with each other in the cross section in the tangential direction A.
Since the amount of falling in the direction opposite to the traveling direction F is reduced and the contact pressure distribution in the block 3 is made uniform, heel and toe wear is less likely to occur. Also,
In the same manner as described above, the amount of deformation of the block 3 in the tire width direction is also reduced, so the steering stability during cornering is also improved.

In the present invention, the normal direction B of the block 3
The orientation angle θ of the kerf 4 with respect to is preferably 20 ° to 70 °. If the orientation angle θ of the kerf 4 is less than 20 °, the steering stability during cornering is improved, but the effect of suppressing uneven wear becomes insufficient, and if it exceeds 70 °,
Although the effect of suppressing uneven wear is improved, steering stability during cornering becomes insufficient.

[0012]

EXAMPLE A tire size of 1000R20, a block height of 20 mm in the tread pattern of FIG. 1, and a depth of 12 mm from the surface of each block provided with a kerf having the shape shown in FIGS. 2 and 4 respectively. The tires of the present invention and conventional tires were manufactured. However, in the tire of the present invention, the orientation angle of the corrugated kerf with respect to the normal direction of the block was 55 °.

Each of these two types of tires was mounted on a rim (rim size: 20 × 7.0T), and the air pressure was set to 7.2.
With 5 kg / cm ² , the braking performance on ice, the uneven wear resistance and the cornering performance were evaluated by the following methods, and the results are shown in Table 1. Braking performance on ice Sudden braking was performed at a speed of 40 km / h on an icy road surface, and the braking distance from when the tires locked until the car stopped was measured. The evaluation results are shown by an index with the conventional tire being 100. The larger the index value, the better the braking performance on ice. Uneven wear-resistant dry paved road surface 10,000 km at an average speed of 40 km / h
After running, the amount of step wear between adjacent sub-blocks in the block was measured. The evaluation result is 100 for the conventional tire.
The higher the index value, the better the uneven wear resistance to heel and toe wear. Cornering performance A slalom test road on which pylons were set up was run at regular intervals, and the average speed was measured. The evaluation results are shown by an index with the conventional tire being 100. The larger the index value, the better the steering stability during cornering.

[0014] As is clear from Table 1, the tire of the present invention has the same on-ice braking performance as the conventional tire, and is excellent in both uneven wear resistance and cornering performance.

[0015]

As described above, according to the present invention, at least one kerf extending in the tire width direction is provided on each surface of a plurality of blocks formed on the tread surface,
Since the kerf is formed in a corrugated shape from both the plan view and the side view of the surface of the block, the sub-blocks divided by the kerf regulate the collapse in the front-rear direction and the left-right direction to each other to reduce the deformation amount of the block. Make it smaller. Therefore, even when traveling on a dry road surface having a high coefficient of friction, the uneven distribution of the ground contact pressure during braking is reduced, so that uneven wear such as heel and toe wear can be effectively suppressed, and at the time of cornering. The steering stability of the vehicle can be improved. In this case, it is not necessary to change the block pattern for the purpose of reducing the amount of deformation of the block, and it is not necessary to form the groove on the tread surface shallowly,
It is possible to maintain a predetermined traveling performance on ice.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a tread pattern of a pneumatic tire of the present invention.

FIG. 2 is a partially enlarged perspective view showing a block of the pneumatic tire of the present invention.

FIG. 3 is a tire circumferential direction sectional view showing the behavior of the pneumatic tire block of the present invention during braking.

FIG. 4 is a partially enlarged sectional view showing a block of a conventional pneumatic tire.

FIG. 5 is a tire circumferential direction sectional view showing the behavior of a conventional pneumatic tire block during braking.

[Explanation of symbols]

 1 main groove 3 block 1a quasi-main groove 3a sub-block 2 sub-groove 4 calf 2a quasi-sub-groove

Claims (1)

[Claims] 1. A pneumatic tire in which a plurality of blocks divided by grooves are formed on a tread surface, and at least one kerf extending in the tire width direction is provided on each surface of the plurality of blocks, the kerf being the block. The pneumatic tire formed in a corrugated shape in both plan view and side view.