JPH03176208A - Tire containing air - Google Patents

Abstract

PURPOSE:To make driving property, braking property, and turn property on ice compatible with each other and improve them by specifying the average value of ratios distributed in all directions and the maximum and minimum ratios in relation to a ratio between the total value of projection length in the direction at a right angle to the direction of working force of a block edge an the total surface area of a tread. CONSTITUTION:The ratio SIGMA Ln(alpha)/s between the total value SIGMA Ln(alpha) concerning a whole block 4 in projection length L(alpha) in the direction at a right angle to the direction of angle alpha of an edge 4e of the block 3 which generates resistance force against working force F which works from the direction of angle alpha in relation to tire circumferential direction E-E' and the whole surface area of tread S is so specified, as the average distribution value in the range from 0 deg. to 360 deg. of angle is specified in the range from 0.035 to 0.05 mm<-1>, and as the ratio of the minimum value to the maximum value in the distribution is specified to 0.7 or more. It is possible owing to this constitution to maintain driving property and braking property on ice and improve cornering performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire, and more particularly to an all-season pneumatic tire that has improved cornering performance while maintaining driveability and braking performance on snowy roads.

[Prior art]

So-called all-season tires designed to be used all year round generally adopt a block pattern in consideration of driving performance and braking performance on snowy and icy roads in winter. The straight-line driving and braking performance of these all-season tires has improved significantly over the past few years, thanks to innovations such as the shape of the grooves forming the blocks and the way the kerfs are carved.

However, the reality is that no effective means has yet been found to improve performance during cornering, other than increasing the adhesive strength of the tread rubber.

[Problem to be solved by the invention]

In view of the above problems, an object of the present invention is to provide a pneumatic tire that improves cornering performance while maintaining good driveability and braking performance on snowy and icy roads by devising a block pattern. It is in.

[Means for Solving the Problems] In order to achieve the above object, a pneumatic tire according to the present invention includes a block basic pattern having a large number of blocks surrounded by grooves having a groove width of 1.5 mm or more, In addition, in such a pattern, the edge portion forming the outer periphery of the block in the tread contact area is set as follows.

In other words, among the edges formed on the outer periphery of the block,
The length of the edge portion that is in the direction that generates a resistance force against the force acting along the tread surface from the direction forming the angle α in the tire circumferential direction is projected in the direction perpendicular to the direction of the angle α above, and the length is summed for all blocks. When the ratio ΣLn(α)/S of the amount ΣLn,(α) and the total tread surface area S is ρ9(α), this ratio ρ9(α) is calculated by changing the angle α from 0° to 360°.
The average value of the distribution when changed in the range of 0.035 ~
0.05 mm-', and the ratio of the minimum value to the maximum value of the distribution is 0.7 or more.

By installing blocks with edges in this relationship on the tire tread surface, it not only provides driving force and braking force when driving straight on snowy roads, but also provides the same frictional force in all directions when cornering. As a result, good cornering performance can be obtained.

Hereinafter, a description will be given using specific examples shown in the drawings.

FIG. 1 shows an example of a block pattern provided in the pneumatic tire of the present invention.

The trend surface 1 is provided with a plurality of grooves 2 in the tire circumferential direction E-E' and a plurality of grooves 3 extending in the width direction so as to intersect with these grooves 2. Both of these grooves 2 and 3 have a groove width of 1.5 mm or more. The block 4 is formed by being surrounded by these grooves 2.3 and forms an edge on its outer periphery.

In such a block pattern, the edges formed on the outer periphery of the blocks within the tread contact width W are a major factor in the generation of frictional force by the tire on snowy and icy roads.

In other words, among the edges surrounding the block, the edges that face in a direction transverse to the force acting along the trend surface during driving engage with the road surface in a claw-like manner, causing wear and tear on the road surface. Generates frictional force.

As mentioned above, FIGS. 2 and 3 illustrate the edge portions of the block that generate frictional force.

As shown in FIG. 2, when the tire is cornering, the block 4 disposed, for example, in a part of the center of the tread pattern in FIG. When receiving the acting force F, the edge portion 4e on the leading edge side facing in a direction transverse to the acting direction generates a drag force as a frictional force. This frictional force is applied to the edge portion 4e
can be expressed as a function of the length L(α) projected onto the line segment K in the direction perpendicular to the direction of the angle α.

In addition, as in the block 4 disposed in a shoulder part of the ground contact area of the tread pattern in FIG.
When the lateral groove 3 is included in the lateral groove 3, the two edge portions d el+ 4 ez generate a resistance force (frictional force) against the external force F, as shown in FIG. Therefore, the sum of the lengths L I (α) and L2 (α) of these two edge portions 4 eI+ 4 O2 projected onto the line segment K becomes a function of the drag force (frictional force).

In this way, the outline of the block is complicatedly curved,
Alternatively, the number of edge portions that generate resistance against external force due to internal lateral grooves can be any number n, so the total length of these projected onto line segment K is ΣLn(α
) can be expressed as

In the present invention, the function ΣLfi(α) of the frictional force generated at the edge portion of such a block is calculated using the total tread surface area S(
= Ratio ρ9(=tread contact width W×tire circumference P)
α), and in the distribution when this ratio ρ9(α) is changed from the angle α=0° to 360°, the ρ9
The average value of (α) is in the range of 0.035 to 0.05 mm-', more preferably in the range of 0.035 to 0.045 mm-', and the ratio of the minimum value to the maximum value of ρ9(α) is It should be 0.7 or more, more preferably 0.75 or more.

As shown in the graph in Figure 4, when the average value of the distribution of ρ9(α) is smaller than 0.035 mm-', the maneuverability and stability performance on dry roads in summer improves, but on snowy and icy roads in winter. Cornering performance becomes lower than permissible limits. If the above average value is larger than 0.05 mm-', on the other hand, cornering performance on snowy and icy roads in winter will improve, but maneuverability and stability performance on dry roads in summer will fall below the allowable limit. .

Therefore, by setting the average value in the range of 0.035 to 0.05 mm-', it is possible to create an excellent all-season tire that balances maneuverability and stability performance on dry roads and cornering performance on snowy and icy roads. . For comparison, FIG. 4 shows the average values of ρ9(α) in commercially available summer tires exclusively for summer and winter tires exclusively for winter.

In addition, in the distribution of ρ9(α) when the angle α is changed from Oo to 360°, by setting the ratio of the minimum value to the maximum value to 0.7 or more, it is possible to It exhibits cornering performance by exerting frictional force against the vehicle. Moreover, wear resistance performance can also be improved. As shown in the graph of Figure 5, the above ρ9(α
The ratio of the minimum value to the maximum value of ) is only 0.68 at most, and the cornering performance and wear resistance performance on snow and ice are both poor.

FIG. 6 shows an all-season tire according to an embodiment of the present invention having the block pattern shown in FIG.
This figure shows the distribution when the value of 9(α) is changed from the angle α=0° to 360°.

The block pattern ρ9(α
) distribution is as shown in the figure, with the maximum value ρ9. maK is 0.
039 mm-', minimum value ρ9. min is 0.031
ml++-', and the average value of the distribution is 0°0
It is 36 mm-'. That is, it is within the range of 0.035 to 0.05 mm defined by the present invention. Also, the ratio of the minimum value to the maximum value ρg, mx,
, /ρ9. □8 is 0.795, which is in the range of 0.7 or more defined by the present invention.

Since this example tire has an average value of 9g(α) of 0.036 mm-', it has excellent cornering performance on snowy and icy roads during cornering on snowy and icy roads in winter.
It can demonstrate a well-balanced control and stability performance during cornering on dry roads in the summer. Further, since the ratio of the minimum value to the maximum value is 0.795, the frictional force is exerted evenly in all directions, as is clear at a glance from FIG.

4. [Effects of the Invention] As described above, the pneumatic tire of the present invention is able to exert frictional force in the same way in all directions by devising the edge portions of the blocks in the block pattern.

Therefore, while maintaining good driving performance and braking performance,
It is possible to improve cornering performance not only on dry roads but also on snowy and icy roads.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of the tread pattern of a pneumatic tire according to the present invention, FIGS. 2 and 3 are explanatory views illustrating the edge portions of the blocks that generate drag, and FIG. Figure 5 shows the relationship between the average value of ρ9(α), maneuverability and stability performance on dry roads, and cornering performance on snowy and icy roads. FIG. 6 is a distribution diagram of ρ9(α) of the example tire of the present invention. 1... Tread surface, 2.3... Groove, 4... Block, 4e, 4e, 4e2... Edge.

Claims (1)

[Scope of Claims] In a pneumatic tire having a block-based pattern consisting of a large number of blocks formed surrounded by grooves with a groove width of 1.5 mm or more, among the edges formed on the blocks in the tread contact area, , for the entire block of length projected in the direction orthogonal to the direction of the angle α, of the edge portion that is oriented to generate a resistance force against the acting force along the tread surface from the direction forming the angle α in the tire circumferential direction. The ratio ΣL_n(α)/S between the total amount ΣL_n(α) and the total tread surface area S is expressed as ρ_g(
α), the average value of the distribution of the ratio ρ_g(α) when the angle α is changed in the range of 0° to 360° is 0.
035 to 0.05 mm^-^1, and the ratio of the minimum value to the maximum value of the distribution is 0.7 or more.