JP2002219910A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high turning performance on icy roads and high uneven- wear resistance for a pneumatic radial tire by ensuring the rigidity of the whole block. SOLUTION: In the tire block 1 which is surrounded by grooves in both circumferencial and width directions, diagonal sipes 2a-2d are formed in a range from the center to the 4 corners of the block. The block 1 is roughly divided into 4 triangular areas A-D. Sipes (3a1 or the like) in the width direction or sipes (4c1 or the like) in the circumference direction are formed on each of the areas A-D. This enlarges an edge element in the lateral direction, so that turning performance is improved for high rigidity of the block 1, thereby attaining high uneven-wear resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to improving the performance of a pneumatic radial tire, particularly a studless tire, on an ice road surface.

[0002]

2. Description of the Related Art Conventionally, some studless tires have a block surrounded by a circumferential main groove (hereinafter referred to as a circumferential groove) and a widthwise transverse groove (hereinafter referred to as a widthwise groove). Many sipe are arranged in such a block, and some sipe is arranged in a circumferential direction in order to improve the turning performance of the tire.

[0003]

However, in such a conventional tire, when the circumferential open sipes are arranged, the rigidity of the entire block is reduced, and the blocks are more likely to fall in the lateral direction, so that the contact area is reduced. .

Further, there are examples in which a large number of sipes are arranged radially from the center of the block to the periphery of the block (for example, Japanese Patent Publication No. 6-2443 and Japanese Patent Application Laid-Open No. 2000-28941).
3). In such a case, since the sipe interval is narrow at the center of the block, the rigidity of the center decreases, and uneven wear occurs at the step.

[0005]

According to the present invention, as a result of diligent studies, four points have been set from the center of the block to approximately four corners of the block.
A diagonal sipe was provided in the direction, and a plurality of width-direction sipes parallel to the tire width direction (a direction parallel to the rotation axis of the tire) were further provided in a substantially triangular area defined by the diagonal sipe.

Accordingly, the diagonal sipe increases the lateral edge component, thereby improving the turning performance. Since the rigidity of the central part of the block where the falling of the block is greatest is increased, the falling can be suppressed during braking. Further, the block is divided into approximately four equal parts by the diagonal sipe, and the rigidity of each divided region is also substantially uniform, so that uneven wear can be suppressed. Since the sipes are not dense at the center of the block, the rigidity of the center of the block is not excessively reduced. Therefore, uneven wear at the center can also be suppressed.

Further, the sipe disposed in the substantially triangular region surrounded by the width direction groove and the diagonal sipe may be structured to be a circumferential sipe parallel to the tire circumferential direction (refer to the tire rotation direction). . In this case, since the lateral edge component further increases, the turning performance is improved.

It is also possible to adopt a structure in which the end of the diagonal sipe is bent in the circumferential direction or the width direction at the corner of the block. That is, when the end of the diagonal sipe is bent in the circumferential direction, the turning performance is improved, and when it is bent in the width direction, the braking performance is improved. Further, in any case, it is possible to prevent the rigidity at the corner of the block from decreasing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a block of a pneumatic radial tire according to the present invention. In FIG. 1, 1 is a block, 2a to 2d are diagonal sipes, 3a1 to 3a4, 3b
Reference numerals 1 to 3b4, 3c1 to 3c2, 3d1 to 3d2 are width sipes, 10a and 10b are circumferential grooves, and 20a and 20b are width grooves. R is the circumferential direction, and W is the width direction.

In FIG. 1, a block 1 has a circumferential groove 1.
0a, 10b and the width direction grooves 20a, 20b. Diagonal sipes 2a to 2d are arranged from the center of the block 1 to the four corners of the block. Therefore, the block 1 is partitioned into a substantially triangular area by the diagonal sipe. A represents a region surrounded by the circumferential groove 10a and the diagonal sipes 2a and 2b,
c, a region surrounded by the width direction groove 20a and the diagonal sipes 2a, 2d is denoted by C,
The area surrounded by b and the diagonal sipes 2b and 2c is referred to as D, respectively.

Further, widthwise sipes are arranged in four regions divided into diagonal sipes. That is, the region A has the width-direction sipes 3a1 to 3a4, and the region B has the width-direction sipes 3b.
1 to 3b4, and the width direction sipes 3c1 and 3c2 in the region C.
And the width direction sipes 3d1 and 3d2 are arranged in the region D, respectively.

The ends of these widthwise sipes with respect to the diagonal sipe may be open to the diagonal sipe (ie, closed sipe) or may not be open (ie, open sipe). May be). When the crossing angle becomes acute, it is preferable that the distance from the diagonal sipe is about 1 mm as a closed sipe. Also, the end to the block end may or may not be open.

By arranging the diagonal sipes 2a to 2d, the lateral edge component is increased, so that the turning performance is improved. Since the rigidity of the central portion of the block where the fall is greatest is improved, the fall can be suppressed and the braking performance is maintained.

Further, since the divided areas A to D are divided into approximately four equal parts, the rigidity of each area is substantially equal, so that uneven wear does not occur in any of the areas, and Is improved. Furthermore, since the sipes are not dense at the center of the block, the rigidity does not decrease excessively, so that uneven wear of the center can be suppressed.

Further, in order to increase the lateral edge component in order to enhance the turning performance, a circumferential sipe may be arranged in the areas C and D instead of the width sipe. That is, as shown in FIG. 2, the circumferential sipe 4c is located in the regions C and D.
1 to 4c4 and 4d1 to 4d4 are respectively arranged. The arrangement of these sipes may be either closed sipes or open sipes, as in the example shown in FIG. Note that only the block 1 is shown in the figure (the same applies to FIGS. 3 to 5 hereinafter).

At the corners of the block, diagonal sipes 2a to 2a
By bending the end of 2d and arranging it in the width direction or the circumferential direction, braking performance or turning performance can be improved. FIG. 3 is an example in which the ends 2a1-2d1 of the diagonal sipes 2a-2d are bent and arranged in the width direction.
The purpose is to improve braking performance. Conversely, FIG.
Is an example in which the ends 2a1-2d1 of the diagonal sipes 2a-2d are bent and arranged in the circumferential direction, with the aim of improving the turning performance. In any case of FIGS. 3 and 4,
It is also possible to prevent the rigidity at the corner of the block from decreasing.

The diagonal sipe, the width sipe, and the circumferential sipe may be zigzag, straight, or a combination thereof, in addition to the illustrated wave shape. Further, the number of width-direction sipes and circumferential sipes arranged in the substantially triangular regions A to D need not be two or four as shown, but can be increased or decreased.

Although the above description has been made on a substantially square block, the present invention can be implemented if the block shape is a quadrangle.

[0019]

Next, a tire according to the present invention (a tire having a sipe pattern shown in FIGS.
It was mounted on a 000 cc front wheel drive vehicle, and the braking distance on ice (ice braking) and the turning performance (ice turning) were evaluated. The tire size is 195 / 65R15,
The tire pressure was 200 kPa.

In the ice braking, a braking distance was measured when a braking operation was performed at full lock from 40 km / h. The reciprocal of the braking distance when the conventional product was set to 100 was determined. Therefore, if it is larger than 100, the braking distance will be shorter than the conventional product.

In ice turning, the vehicle runs at a speed of 20 km / h,
When the vehicle goes straight on an icy road and turns the steering wheel at a constant speed of 90 degrees per second, the evaluation is made based on the maximum value of the cornering force generated on the front tires. The cornering force is measured by measuring the vehicle speed, the side slip speed, the lateral acceleration, the yaw rate, and the steering angle with a sensor attached to the vehicle, and calculating the axial lateral force of the front wheel and the rear wheel with respect to the slip angle. It is represented by an index with the maximum cornering force of a conventional product as 100. Therefore, if it is larger than 100, the cornering force maximum value is large and the turning performance is high.

Table 1 shows Examples 1-4 and conventional products.
It is the table | surface which put together the result of the ice performance evaluation. In Table 1, Examples 1 to 4 are tires having the sipe patterns shown in FIGS. Further, the conventional product is a tire having a sipe pattern shown in FIG.

[0023]

[Table 1]

In the first embodiment, since the lateral edge component due to the diagonal sipe (eg, 2a) is increased, the turning performance is improved as compared with the conventional product. In addition, since the rigidity of the block is increased, the falling down is suppressed, and as a result, the braking performance is slightly improved. In the second embodiment, a part of the width sipe (such as 3c1) is replaced with a circumferential sipe (such as 4c1), so that the lateral edge component is further increased and the turning performance is improved. Moreover, since the rigidity of the block is kept increased, the braking performance is not inferior to the conventional product.

In the third embodiment, the end of the diagonal sipe (2a1
) Are bent in the width direction, the edge component in the front-back direction is increased, and the braking performance is improved, but the turning performance is not significantly degraded. Further, in the fourth embodiment, the end (2a1, etc.) of the diagonal sipe is bent in the circumferential direction, so that the lateral edge component is increased and the turning performance is improved, but the braking performance is significantly deteriorated. Not. Therefore,
It can be said that the tire according to the present invention has improved turning performance on an ice road surface as compared with a conventional product while maintaining braking performance on an ice road surface.

[0026]

As described above, in the pneumatic radial tire of the present invention, a diagonal sipe is arranged from the center of the block to the corner of the block, and the widthwise sipe or the sipe is formed in a region defined by the diagonal sipe. A circumferential sipe was arranged. As a result, the lateral edge component increases, the turning performance on an ice road surface is improved, and the rigidity of the block is increased.
The braking performance on icy roads was maintained, and the uneven wear resistance was also improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block of a pneumatic tire of the present invention.

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

FIG. 3 is a view showing a block of the pneumatic tire of the present invention.

FIG. 4 is a view showing a block of the pneumatic tire of the present invention.

FIG. 5 is a diagram showing a block of a conventional pneumatic tire.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tire block 2a-2d Diagonal sipe 3, 3a1-3a4, 3b1-3b4, 3c1-3c
2, 3d1 to 3d2 Width sipe 4c1 to 4c4, 4d1 to 4d4 Circumferential sipe 10a, 10b Circumferential main groove 20a, 20b Width lateral groove A to D Area partitioned by diagonal sipe R Tire circumferential direction W Tire width direction

Claims (3)

[Claims] In a pneumatic radial tire, a diagonal sipe is arranged in a block surrounded by a circumferential main groove and a widthwise lateral groove cut in a tire surface from a center of the block to approximately four corners, A pneumatic radial tire having a widthwise sipe arranged in a substantially triangular area defined by the diagonal sipe. 2. In a pneumatic radial tire, a diagonal sipe is arranged from a center portion of the block to approximately four corners in a block surrounded by a circumferential main groove and a widthwise lateral groove carved on the tire surface, In the substantially triangular area surrounded by the diagonal sipe and the circumferential main groove, a sipe in the width direction is provided.
A pneumatic radial tire in which a circumferential sipe is arranged in a substantially triangular area surrounded by the diagonal sipe and the widthwise lateral groove. 3. The pneumatic radial tire according to claim 1, wherein an end of the diagonal sipe is bent in a circumferential direction or a width direction at a corner of the block.