JP2539202B2 - Pneumatic tires for passenger cars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is
The present invention relates to a pneumatic tire for passenger cars, which has significantly improved snow steering stability.

[Conventional technology]

Conventionally, in order to improve wet performance, a pneumatic tire in which a tread pattern of the tire is used as a directional pattern is known (see, for example, JP-A-57-194106 and JP-A-60-45404). As can be seen in these known pneumatic tires, tires with a directional pattern on the tread do have good wet performance but do not improve snow performance.

Further, FIGS. 4, 5 and 6 show examples of tread patterns of conventional tires.

In order to improve the snow performance, it is usual to put a kerf in the block forming the tread pattern, but if the kerf is simply put in the block, the shear rigidity of the block of the tread is lowered, There is a drawback that the cornering force is reduced, and as a result, the dry steering stability is reduced.

[Object of the Invention]

An object of the present invention is to provide a pneumatic tire for passenger cars, which is capable of achieving both dry steering stability and snow performance without impairing wet performance and is suitable for all-season tires.

[Structure of Invention]

The present invention that achieves the above object is to provide a plurality of main grooves extending in the tire circumferential direction on a tread surface in which a tire rotation direction is designated as one direction, and a sub groove extending in the tire width direction so as to intersect the main grooves. Along with forming the groove, the auxiliary groove extends from the tire center side toward the shoulder side while being inclined in the direction opposite to the tire rotation direction, and a large number of blocks are defined by the main groove and the auxiliary groove. In a pneumatic tire for passenger cars, at least one kerf extending in the tire width direction along the sub-groove is provided in a tire rotation direction rear region of the block so that both ends communicate with the main groove, and the tire in the block is provided. It is characterized in that the shear rigidity on the front region side in the rotational direction is made larger than that on the rear region side.

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

FIG. 1 is a pneumatic tire for passenger cars of the present invention (hereinafter, referred to as
FIG. 3 is a perspective view showing one embodiment of a tire), and P is an example of a directional pattern provided in the tire of the present invention.

FIG. 2 is an enlarged plan view showing the directional pattern P of FIG. 1 more specifically. A plurality of main grooves 1 extending in the tire circumferential direction are provided on a tread surface whose tire rotation direction is designated in one direction as indicated by an arrow, and a sub groove 2 extending in the tire width direction so as to intersect with the main groove 1. Are formed. The sub-groove 2 is configured to extend from the tire center side toward the shoulder side while being inclined in a direction opposite to the tire rotation direction, and the main groove 1 and the sub-groove 2 partition and form a large number of blocks 3. ing.

As can be seen from the figure, the pattern provided on the tire tread portion of the present invention is a directional pattern corresponding to the rotation direction of the tire, and by having such a directional pattern, the tire of the present invention has an excellent wetness. Show performance.

The feature of the present invention is that the blocks, which have a close and inseparable relationship with the directional pattern, have different shear rigidity within the blocks. That is, a kerf 4 extending in the tire width direction along the sub-groove 2 is provided in the tire rotation direction rear region of the block 3 so that both ends communicate with the main groove 1, and the shear rigidity of the block on the tire rotation direction front region side. Is large and the shear rigidity on the rear region side is small.

In the present invention, there is a difference in the shear rigidity between the front and rear regions in the tire rotation direction of the block, and that the shear rigidity of the front region of the block is higher than that of the rear region means that when a high driving force is applied to the tire. The part on the side to which the driving force is applied is locally deformed, and the part on the opposite side is deformed into a raised shape.

FIG. 3 is a plan view showing an example of a deformed state of the block 3 of the tire when the tire of the present invention is driven,
The shaded area indicates the grounded area and the remaining white area indicates the non-grounded area. It can be seen from the figure that the block 3 is deformed unevenly due to the difference in shear rigidity of the block 3 in the tire rotation direction.

In particular, when traveling on a road surface having a high coefficient of friction such as a dry road surface, it is considered that a high driving force is transmitted to the tire and the block 3 of the tire undergoes the deformation as shown in FIG. It can be said that the front part of the block, which is in direct contact with the road surface, greatly contributes to the shear rigidity of the block. Therefore, even if the kerf is provided in the rear region of the block to reduce the shear rigidity, the dry steering stability is not affected much.

On the other hand, on a road surface having a low coefficient of friction such as a snow road, only a small driving force is transmitted to the tires, so that the block does not deform like the dry road surface, and the entire block comes into contact with the road surface. Therefore, the snow performance can be improved by providing a kerf in the rear area of the block to dig up and increase the frictional force, and also when the braking force is applied to the tire, the snow performance is improved by the same effect. .

In order to make the shear rigidity of this block lower in the rear region than in the front region in the tire rotation direction, the number, depth, width and / or density of the kerfs provided in the block should be determined in the front region in the tire rotation direction of the block. It can also be lowered by varying in the area and the back area. Usually, the number of kerfs in the rear area is larger than that in the front area of the block, the depth of the kerf is deep, the width of the kerf is increased, and these are combined with each other. The kerf densities can be made different to reduce the shear rigidity of the rear region. At least one kerf 4 may be provided in a rear region of the block 3 in the tire rotation direction.

〔Example〕

Hereinafter, the effects of the present invention will be described more specifically by way of examples.

In the examples, the shear rigidity of the block, the wet circle turning test, the snow climbing test, and the dry steering stability (slow ram running test) are as follows.

Shear rigidity of block: Using "rotary disk friction tester" manufactured by Iwamoto Seisakusho,
Under the conditions of pressure 1Kg / cm ² , friction speed 1.6m / hr, temperature 25 ℃,
The shear rigidity of each block was measured on the safety walk road surface, and shown as "value in front area / value in rear area".

Wet circle turning test: A test tire was mounted on a domestic FF small car, and it ran 5 laps clockwise around the circumference course of a radius of 30 m set to a water depth of 5 mm at the limit speed, and the average of the center 3 laps was the tire limit speed. And the limit lateral G was calculated from the limit speed. The larger this value, the better the wet performance.

In the above test, the rim was 6JJ × 14 and the internal pressure was 2.0.
It was set to Kg / cm ² .

Snow climbing test: A test tire was attached to a small domestic FF vehicle, and the test vehicle was started from the stopped state at the 1st gear in a compressed snow road with a gradient of 13%, and the climbing acceleration time in the 30m section was measured.

The test was performed 5 times, and the time of 3 times in the center was averaged to obtain the hill acceleration time. The larger this value, the better the ability to climb on snow.

Dry steering stability: The time required to drive an actual vehicle on the slow ram test road. The smaller this value, the better the drum steering stability.

Example 1, Comparative Examples 1 to 3 Steel belt 1 × 5 (0.25) 40 layers per 50 mm, a belt layer obtained by laminating 40 strands at a bias of 20 ° with respect to the tire circumferential direction, polyester 1500D / 2 55 layers per 50 mm It has a carcass layer arranged at substantially 90 ° to the tire circumferential direction, a bead structure in which a JIS hardness 90 bead filler is sandwiched between the carcass body and the carcass turnup, the size is 195 / 60R14, and only the tread pattern is The above test was conducted using four different types of tires, that is, tires having the patterns shown in FIGS. 2, 4, 5, and 6, respectively, and the results shown in Table 1 were obtained.

[Advantages of the Invention] As described above, the present invention provides a plurality of main grooves extending in the tire circumferential direction on the tread surface in which the tire rotation direction is designated as one direction, and the tire width so as to intersect with the main grooves. And a sub-groove extending in the direction, and the sub-groove is inclined from the tire center side toward the shoulder side in a direction opposite to the tire rotation direction and extends, and the main groove and the sub-grooves form a large number of blocks. In the pneumatic tire for passenger cars in which the section is formed, in the tire rotation direction rear region of the block, at least one kerf extending in the tire width direction along the sub-groove is provided so that both ends communicate with the main groove, Since the shear rigidity of the block in the front region side in the tire rotation direction is made larger than that in the rear region side, the following excellent effects are exhibited.

That is, since the block is provided with a kerf whose both ends extending in the tire width direction communicate with the main groove, snow performance can be ensured by the edge effect of the block facing the kerf, while the kerf is used as a rear region in the tire rotation direction. Since the shear rigidity on the front region side of the block is made larger than that on the rear region side, the driving force can be secured during running on a dry road surface by the block front region having the increased shear rigidity. It is possible to achieve both the snow performance and the dry steering stability without causing the deterioration of the dry steering stability due to the provision of the above.

Moreover, since the directional tread pattern is formed by the main groove in the tire circumferential direction and the auxiliary groove extending inclining in the tire width direction on the tread surface in which the tire rotation direction is designated as one direction, wet performance is improved. There is no loss.

Further, since the kerf extends in the tire width direction along the sub-groove, significant uneven wear does not occur in the small block portion on the rear side of the block divided by the kerf.

[Brief description of drawings]

FIG. 1 is a perspective view showing one embodiment of a pneumatic tire for passenger cars of the present invention, and FIG. 2 is a tread pattern 1 of the present invention.
FIG. 3 is an enlarged plan view showing an example, FIG. 3 is a plan view showing an example of a deformed state of a block of the tire of the present invention when driven, and FIGS. It is an enlarged plan view showing an example of a tread pattern. P: Tread pattern, 3 ... Block, 4 ... Calf.

Claims (1)

(57) [Claims] 1. A plurality of main grooves extending in the tire circumferential direction are provided on a tread surface whose tire rotation direction is designated as one direction, and sub-grooves extending in the tire width direction are formed so as to intersect the main grooves. At the same time, the sub groove is configured to extend from the tire center side toward the shoulder side while being inclined in the direction opposite to the tire rotation direction, and a large number of blocks are defined by the main groove and the sub groove to form a passenger car pneumatic In the tire, in the tire rotation direction rear region, at least one kerf extending in the tire width direction along the auxiliary groove is provided so that both ends communicate with the main groove, and the tire rotation direction front part of the block. Pneumatic tires for passenger cars that have greater shear rigidity on the area side than that on the rear area side.