JP3062359B2 - Studless tires for passenger cars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a studless tire for a passenger car having improved performance on ice and snow roads.

[0002]

2. Description of the Related Art There is a studless tire for a passenger car having a tread pattern shown in FIG. 10 for securing traction performance, braking performance and the like on an icy road. That is, in FIG.
The center block 2 and the left and right shoulder blocks 3
Are arranged at intervals in the circumferential direction, and each of the blocks 2 and 3 is composed of an aggregate of filaments 5 defined by sipes 4 formed in the tire axial direction (tread width direction).

[0003]

In the prior art shown in FIG. 10, as the size of each block 2 and 3 increases, the size of the filament 5 also increases and the rigidity increases, so that the tread width is increased or the actual contact area is increased. When the contact pressure decreases as in the case of increasing the number, the filaments 5 do not sufficiently fit on the icy and snowy road surface, so that the traction performance, the braking performance, etc. are just one step away.

The performance required for a studless tire includes traction & brake and grip in the lateral direction. The traction & brake performance is determined by the number and length of the sipe (lateral sipe) perpendicular to the rotation direction. The grip in the horizontal direction is affected by the number and length of the sipe (vertical sipe) extending in the rotating direction (by the number and length of the edges).

[0005] In order to achieve both of these performances, it is conceivable to form an aggregate of vertical and horizontal filaments in which a block is divided by grid-like vertical and horizontal sipes. However, in this case, when trying to improve the lateral grip without decreasing the traction & braking performance, the depth of the vertical and horizontal sipe (when trying to increase the number of vertical sipes without reducing the number of horizontal sipes) is reduced. Since they are equivalent, the rigidity of the pattern is excessively reduced, and the wear and handling stability on a non-snowy road are extremely deteriorated.

[0006] Therefore, there is a trade-off between the traction & brake performance and the lateral grip performance in order to ensure the steering performance on a non-snowy road. The present invention
In view of such a situation, a first object is to improve the ice and snow performance by further dividing the filament by a sipe, thereby reducing the rigidity of the filament, and thereby ensuring the fit to the ice and snow road surface.

A second object of the present invention is to provide a shallow groove sipe shallower than the lateral sipe to ensure a certain degree of fit to ice and snow road surfaces and to improve lateral grip performance without sacrificing wear and steering stability. It is in.

[0008]

According to the present invention, a center block 13 and a shoulder block 14 are provided on a tire tread portion 10.
Having a block pattern arranged at intervals in the circumferential direction, the center block 13 and the shoulder block
14 is a studless tire for a passenger car consisting of an aggregate of filaments 16 partitioned by a horizontal sipe 15,
In order to achieve the first object, the following technical measures are taken.

That is, according to the present invention, the center block 13 and the shoulder block 14 have a ground contact area of 800 mm ² or more and a tire tread portion.
At least 30% of the land in 10 is separated from the horizontal sipe 15 by a filament 16A with a ground contact area of 40 mm ² or less.
The vertical sipe 17 is replaced with the filament 16 or the center block 13 and the shoulder block constituting the center block 13.
The filament 14 is formed on the filament 16 constituting the loop 14 .

Further, in the present invention according to claim 2, the filament 16 of one or both of the center block 13 and the shoulder block 14 has a depth of 0.5 mm or less.
A shallow groove vertical sipe 17A different from the horizontal sipe 15 having a width of 3.0 mm and a width of 2.0 mm or less is formed at an interval of 5 mm to 30 mm, and only the ground surface of the filament 16 is divided. Things.

[0011]

According to the first aspect of the present invention, when the tire travels on an icy and snowy road surface, the filament 16A is driven by the lateral sipe 15,
And it becomes easy to adhere to a road surface via the vertical sipes 17. According to the present invention according to claim 2, without sacrificing wear and steering stability on a certain degree to non icy and snowy road surfaces the stiffness of the block pattern, lateral grip performance on icy and snowy road surfaces due to the shallow longitudinal sipes 17A To secure.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;
The tire tread part 10 is composed of a land part by a block 11 and a sea part by a groove 12, and the block 11 is a center block 13
And a so-called block pattern in which the left and right shoulder blocks 14 are arranged at intervals in the circumferential direction (tire rotation direction A) via the grooves 12.

The center block 13 and the shoulder block 14 are an aggregate of filaments 16 partitioned into narrow widths by a so-called horizontal sipes 15 having an opening width of about 1 to 1.5 mm and a depth equal to or more than half the depth of the grooves 12. Consists of each block 1
3, 14 have a contact area of 800 mm ² or more. In the first embodiment shown in FIG. 1, the center block 13 is divided into filaments 16A having a ground contact area of 40 mm ² or less in 30% or more of the land.
So-called vertical sipe different from horizontal sipe 15
The vertical sipe 17 has the same opening width and depth as the horizontal sipe 15, and the center block 13 is constituted by an aggregate of filaments 16A arranged in a vertical and horizontal lattice.

In the second embodiment shown in FIG. 2, the center block 13 is constituted by an assembly in which the filaments 16A arranged in a vertical and horizontal lattice are made smaller than in the first embodiment, and the rigidity is lower than that of the first embodiment. As a result, the road surface fit is improved. In the third embodiment shown in FIG. 3, the center block 13 is constituted by an aggregate of filaments 16A arranged in a fine vertical and horizontal lattice, and the left and right shoulder blocks 14 are also arranged in a vertical and horizontal lattice by providing a vertical sipes 17. In the third embodiment shown in FIG. 4, the left and right shoulder blocks 14 are arranged in a fine vertical and horizontal lattice in the second embodiment.
Is an aggregate.

In each of the embodiments described above, the tire is a studless radial tire for a passenger car, and 30% or more of the land portion is provided with a filament 16A of 40 mm ² or less.
In the following, it is difficult to obtain sufficient performance due to the rigidity of other parts, and the reason for setting it to 40 mm ² or less is that if it is more than 40 mm ² , the rigidity becomes too high and it is difficult to obtain performance, and 800
was a mm ² or more blocks, the less the block because there is no possible in 40 mm ² or more filaments too high the rigidity of the whole block.

The directions of the horizontal sipe 15 and the vertical sipe 17 are not limited to vertical and horizontal (orthogonal) directions but may be oblique. Here, in Table 1 below, the results of testing the performances of the conventional example shown in FIG. 10 and the first to fourth embodiments of the present invention are indicated by an index with the conventional example being 5. The tire is 20
It is a 5 / 60R15 studless, has an internal pressure of 2.0 kg / cm ² , and has a road surface of ice and snow.

[0017]

[Table 1]

FIGS. 5 to 9 show a first embodiment of the present invention according to claim 2.
5 to 5 show examples. Parts common to those in FIGS. 1 to 4 are denoted by common reference numerals, and differences will be described below. The first embodiment of FIG. 5, another shallow vertical support <br/> type 17A is a transverse sipe 15, i.e., depth 0.5 ～3.0Mm, the following shallow longitudinal sipes 17A width 2.0 mm, 5 mm to It is formed on all of the filaments 16 constituting the center block 13 and the shoulder block 14 at intervals of 30 mm, and only the ground plane is divided.

[0019] The second embodiment of Figure 6, the above-mentioned shallow longitudinal sipes
17A to the filament 16 of the shoulder block 14, and
In the third embodiment shown in FIG. 7, it is formed on the filament 16 of the center block 13. Further, in the fourth embodiment shown in FIG. 8, the above-described shallow groove vertical sipes 17A are not formed on all the filaments 16 constituting the center block and the shoulder block 14, but are formed according to the required performance. is there.

In the fifth embodiment shown in FIG. 9, the filament 16 forming the shoulder block 14 is divided by a horizontal sipe 15 and a vertical sipe 17B having the same groove depth as the horizontal sipe 15 defines. obtained by an assembly of filaments 16B, the vertical filament 16B, lateral shallow lateral sipe 1
7C is provided to help improve traction.

[0021] Here, the shallow grooves longitudinal sipes 17A in the first to fifth embodiment according to claim 2, and the shallow grooves to a width of sipes 17C 0.5 mm to 3.0 mm the sipe depth is at 0.5mm or less This is because the edge effect of the vertical sipe cannot be expected, and if it is 3.0 mm or more, the rigidity of the pattern is excessively reduced, and the wear on non-snowy road surface and the reduction in maneuverability are increased. The reason why the sipe width is set to 2.0 mm or less is that if the sipe width is 2.0 mm or more, the performance on ice is greatly reduced because the contact area becomes too large, which is not practical.

The reason why the sipe interval is set to 5 mm to 30 mm is 5 mm
In the following, the pattern rigidity is too low, and the above-mentioned problem occurs. When the thickness is 30 mm or more, the sipe is too sparse, and the effect of the vertical sipe cannot be expected. The vertical sipe and the horizontal sipe may be slightly inclined. The shallow vertical sipe and the horizontal sipe need not be orthogonal.

Table 2 below shows the performance test results of the first embodiment of the present invention according to claim 2 and the conventional example shown in FIG.

[0024]

[Table 2]

The tire is studless of 205 / 60R15 and has an internal pressure of 2.0 kg / cm ² . The performance is represented by an index using the conventional example as a control, and the larger the numerical value, the better. The same applies to the second to fifth embodiments according to claim 2.

[0026]

The present invention is as described above. According to the first aspect of the present invention, by reducing the rigidity of the block in the tire tread portion, traction performance on icy roads, braking performance, steering response, and A studless tire for a passenger car with improved operability can be provided.

According to the second aspect of the present invention, it is possible to increase the number of vertical sipes (the number of edges affecting the horizontal grip) without reducing the rigidity of the block pattern. The lateral grip performance can be improved without sacrificing maneuverability and without sacrificing traction and braking performance on icy and snowy roads.

[Brief description of the drawings]

FIG. 1 is a developed plan view of a first embodiment of the present invention according to claim 1;

FIG. 2 is a developed plan view of a second embodiment of the present invention according to claim 1;

FIG. 3 is a developed plan view of a third embodiment of the present invention according to claim 1;

FIG. 4 is a developed plan view of a fourth embodiment of the present invention according to claim 1;

FIG. 5 is a developed plan view of the first embodiment of the present invention according to claim 2;

FIG. 6 is a developed plan view of a second embodiment of the present invention according to claim 2;

FIG. 7 is a developed plan view of a third embodiment of the present invention according to claim 2;

FIG. 8 is a developed plan view of a fourth embodiment of the present invention according to claim 2;

FIG. 9 is a developed plan view of a fifth embodiment of the present invention according to claim 2;

FIG. 10 is a developed plan view of a conventional example.

[Explanation of symbols]

 10 Tire tread 13 Center block 14 Shoulder block 15 Horizontal sipes 16 Filament 16A Filament 17 Vertical sipes 17A Shallow groove sipes

Claims (2)

(57) [Claims] 1. A block pattern in which a center block (13) and a shoulder block (14) are arranged at intervals in a circumferential direction on a tire tread portion (10), and the center block (13) and the shoulder block ( 14) The horizontal sipe
In a studless tire for a passenger car comprising an aggregate of filaments (16) partitioned by (15), the center block (13) and the shoulder block (1)
4) has a contact area of 800 mm ² or more, and a contact area of 40% or more of the land on the tire tread (10).
mm ² or less of the order to divide the filament (16A) lateral Sai <br/> filaments constituting the flop (15) center block another longitudinal sipe (17) and (13) (16) or the center block (13 )
And the filaments that make up the shoulder block (14)
A studless tire for a passenger car, which is formed as described in (16). The tire tread (10) has a block pattern in which a center block (13) and a shoulder block (14) are arranged at intervals in a circumferential direction, and the center block (13) and the shoulder block (14) are arranged. 14) The horizontal sipe
In a studless tire for a passenger car comprising an aggregate of filaments (16) partitioned by (15), the center block (13) and the shoulder block (1)
4) to one or both filaments (16),
Depth 0.5 mm to 3.0 mm, another shallow longitudinal sipes and the transverse Sai <br/> flop which is the width 2.0mm or less (15) to (17A), formed at intervals of 5mm~30mm filaments ( 16) A studless tire for a passenger car, wherein only the ground contact surface is divided.