JPS62146703A - Tire for vehicle having excellent on-snow performance - Google Patents

Abstract

PURPOSE:To improve the braking performance and the climbing performance on an iced pavement by providing a specific inclined section in a main groove continuous in the circumferential direction of the tire tread and a thin groove or siping continuous to the main groove while specifying the total extension of the open section of a groove opening to the shoulder section. CONSTITUTION:A main groove 1 continuous to the circumferential direction A of a tire tread is provided with a section inclining with an angle smaller than 45 deg., preferably smaller than 40 deg., against a meridian Tm of the tire over the range more than 60% of the substantial total extension measured on the center line C of the width W of main groove. A thin groove or siping where one or both ends are coupled to the main groove 1 is also provided with a section inclining with an angle smaller than 45 deg., preferably smaller than 40 deg., against a meridian of tire over the range more than 60% of the total extension measured on the center line of the width of said thin groove or siping. The total extension of the open section of the groove opening to the shoulder section is set to be shorter than 15% of the circumferential length of the shoulder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pneumatic tire for a vehicle, and particularly to a snow tire for a vehicle having a tread pattern with excellent on-snow performance.

(Prior Art) Snow-clamping effect, frost column shearing effect, contact surface friction effect, and edge effect are conventionally recognized as elements that realize the performance of this type of pneumatic vehicle tire on snow.

(Problem to be solved by the invention) However, in order to improve the snow-stopping effect, it is necessary to increase the footprint width and length.
Therefore, the snow-stopping effect naturally has an upper limit depending on the tire size. The frost column shearing effect and the contact surface friction effect are originally in a contradictory relationship, and increasing the negative ratio to increase the frost column shearing effect causes uneven wear, shortening tire life, and reducing the contact surface friction effect. If the actual footprint area is increased to increase the ground effect, there is a problem in that the frost column shearing effect is reduced. Furthermore, if the groove component is increased in order to increase the edge effect, the trend rigidity decreases, causing problems such as noise, uneven wear, and stone bite.

The present inventor conducted an actual vehicle test to determine the contribution of each of the above-mentioned elements to the overall on-snow performance, and as a result, confirmed that the frost column shearing effect has the largest contribution to the on-snow performance.

The frost column shearing effect is caused by snow entering the pattern grooves and clogging them when the tires are transferred on a snowy road surface, and the clogging snow (physically speaking, ice) and the snow or ice on the road surface being added to the tread surface. The clogging snow is instantly fused (sintered) and bonded together by the pressure action, and the snow or ice on the road surface is separated again by the shearing force, and at this time, the shearing force generated between the two creates a frictional force. This improves on-snow performance such as braking performance and climbing performance on snow.

For this reason, the present invention intends to proactively create frost pillars, different from the conventional view, with respect to the frost pillar shearing effect, which is most effective for snow performance. As mentioned above, if the negative ratio is increased, there will be performance disadvantages such as shortened tire life and uneven wear, so we provide a tire pattern that can minimize the disadvantages and improve the frost column shearing effect. This is what I am trying to do.

(Means for Solving the Problems) While studying the frost column shearing effect from the above-mentioned perspective, the inventor observed the effects of ruts on tires or ruts during rolling on snowy roads. The strength of the remaining frost column correlates with the magnitude of the shearing force, which in turn correlates with the tire's on-snow performance (braking, acceleration), and the stronger the frost column, the better the snow performance. The smaller the amount of snow that comes out, the more snow is taken into the tread surface, forming a strong frost column.Similarly, the smaller the amount of snow that is taken in from the front when braking, especially when locking, the less the amount of snow that is thrown out from the shoulder area. We confirmed the fact that strong frost pillars are formed.

The present invention was made based on the recognition of such facts, and the most important feature of the present invention is that it breaks the conventional common sense and
The purpose is to actively trap a large amount of snow and water particles in the grooves of the tread pattern, causing them to become clogged. Therefore, according to the present invention, as shown in FIG. Tire meridian N
A narrow groove or sipe having a part inclined at an angle of 45° or less, preferably 40' or less with respect to MTm, and connected at one or both ends to the main groove 1, on the width center line of these narrow grooves or sipes. It has a part that is inclined at an angle of 45 degrees or less, preferably 40 degrees or less with respect to the tire meridian in a range of 60% or more of the measured phase length, and the total length of the opening of the groove that opens in the shoulder part is the shoulder circumference. It is characterized by being 15% or less of the length.

(Function) If the angle of inclination to the tire meridian of the main groove, narrow groove, sipe, etc. A large amount of snow and water powder can clog the
If the angle exceeds 5°, the length of the groove edge facing the direction of travel will be short, making it difficult to obtain a resonant component.

In addition, the shoulder hollow should have a structure in which there are no openings such as grooves or sipes, or even if openings are provided, the total length of these openings should be 15% or less of the shoulder circumference. When braking, especially when locking, it is possible to reduce the burrs of snow and ice particles such as wet marks behind the tire, and to prevent snow and water particles captured on the tread surface from flowing out to the side surfaces. Therefore, it is best not to provide an opening, but in practice there may be cases where it is necessary to attach a chain, so if the chain is taken into consideration, a minimum amount of gouging is necessary.

Further, according to the present invention, in order to improve the frost column shearing effect by the grooves of the tread pattern, it is preferable that the grooves have the following configuration when the tire is filled with air.

(1) The pattern negative ratio is 34% or more, preferably 40% or more and 50% or less. The reason for this is that a negative ratio of 34% or more is generally required as a prerequisite for a snow tire.

If it is less than 34%, the frost column volume will be small, and the shearing force cannot be expected, and at the same time, the edge component will also naturally decrease.

A level of 40% or more is often used in low-temperature tires where the sintering power of snow crystals is weak, but in the present invention, it is necessary to incorporate a large amount of snow into the tread surface, so a higher value is better. However, if it exceeds 50%, the frost column density becomes small, meaning that there is not enough snow and water powder to form a frost column, so not only can no shearing force be expected, but disadvantages such as uneven dread wear and tire life will occur. It is.

(2) Regarding the cross-sectional shape of the main groove 1, as shown in Fig. 2, the included angle β formed by both walls is 14° or more and 36° or less in a cross section perpendicular to the longitudinal center line of the groove. It is better to The reason for this is that if the shape is less than 14 degrees, it becomes close to a U-shaped groove shape, and the effect of tightening compressed snow and water powder becomes less, and as a result, the shearing force of the frost column becomes smaller. When the angle is larger than 36°, the snow is clamped statically, but dynamically, especially during braking, the edge part produces a warping effect, causing snow and water powder to escape from the groove, so it is insufficient. You can't expect a lot of snow.

(Example) Figures 3 to 5 show various examples of tread patterns according to the present invention.

In the example shown in FIG. 3, the entire main groove l continuous in the tire circumferential direction A on the tire tread 2 is defined as the tire meridian 'fy'% T
It is inclined at an angle of 45° or less with respect to m.

In addition, all the narrow grooves 3 and sipes 4 connected to the main groove 1
The tires are also inclined at an angle of 45° or less with respect to the tire meridian Tm. Furthermore, no groove is opened in the shoulder portion 5.

In the example shown in FIG. 4, the entire main groove 1 surrounding a large number of small blocks 6 in the tire tread 2 and continuous in the tire circumferential direction and the narrow groove 3 connected to the main groove 1 are connected to the tire meridian Tm.
It is tilted at an angle of 45° or less. In this example, the narrow groove 3 is opened in the shoulder portion 5 as shown by 3a, but the opening length W2+W within one pattern cycle in the circumferential direction of the tread pattern in the tread 2 is the length of one pattern cycle. The ratio (Wz+Wt)/W+ to W is set to 0.1 or less.

FIG. 5 shows that in the tread 2, the main groove l continuous in the tire circumferential direction is inclined at an angle of 45° or less with respect to the tire meridian Tm over a range of 60% or more of the total length of the substantial center line 1c. An example is shown below.

(Effects of the Invention) According to the present invention, braking performance and hill climbing performance, which are the most important characteristics required of a tire on icy and snowy roads, can be improved compared to conventional products. In particular, when spikes are attached to the tire tread, when it locks up when braking on ice,
Braking performance is greatly improved because the water particles stay within the trend plane and form frost columns (icicles) within the grooves.

Furthermore, when no opening is provided in the shoulder portion, the effects of reducing noise and improving uneven wear characteristics of the shoulder portion can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the basic structure of the main groove of the tire tread of the present invention; FIG. 2 is a cross-sectional view of the main groove shown in FIG. 1 taken at right angles to the groove longitudinal center line; 5 are partial front views of tire treads showing various examples of tire tread patterns according to the present invention. Figure 1 Figure 2 14≦β≦36

Claims (1)

[Claims] 1. The main groove that extends in the circumferential direction of the tire tread and the grooves such as narrow grooves and sipes connected to this main groove extend over 60% or more of the actual total length measured on the center line of the groove width, and the width is 45% relative to the tire meridian. having a sloped part at an angle of less than or equal to
A vehicle tire with excellent on-snow performance, characterized in that the total length of the openings of the grooves opening in the shoulder portion is 15% or less of the shoulder circumference.