JPH03112705A - Studless pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve total riding comfort by forming at least three inter- sections at a plurality of blocks formed on a tread for making notches to separate a plurality of sub-clocks, and specifying the predetermined negative factor. CONSTITUTION:A tire has a carcass layer extended at an angle of 90 deg. with the equatorial surface thereof, and a belt layer extended at a small angle with the aforesaid surface. Also, a tread T has a plurality of grooves 1 and a plurality of blocks 2 divided therewith. In this case, notches 3 comprising a vertical sheeting 3a extended along the periphery of the tread T and a horizontal sheeting 3b extended along the width of the tread T, are provided. Three intersections (p) are thereby formed in the blocks 2, and the blocks 2 are divided into a plurality of sub-blocks 2a. In addition, a negative factor obtained by deducting the total area of the blocks 2 from the ground contact area of the tread T is set within 30% to 50%.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a studless pneumatic radial tire that is particularly useful when driving on road surfaces with rapid changes such as ice and snow. Direction along (
By balancing the edge effects in the direction along the width of the tread (hereinafter referred to as the circumferential direction) and the direction along the width of the tread (hereinafter referred to as the width direction), the overall driving feeling is further improved.

(Prior Art) Tires used for driving on snowy and/or icy roads are required to have high braking performance and traction performance, and as a means to achieve this, sipes have been commonly used to increase edge components.

The specific method for forming the sipes is to create lateral sipes in the center area of the tread that run along the width of the tread, which are effective in improving the straight-line performance of the tire, and in both end areas of the tread, which are effective in improving the tire's performance on the sides. Possible examples include one provided with a certain vertical sipe (see FIG. 11), or one formed with an inclined sipe that is a combination of the above-mentioned vertical sipe and horizontal sipe (see FIG. 12).

However, with the above-mentioned type of tire in which specific sipes are provided in blocks in specific areas, although almost satisfactory performance in terms of traction and braking can be obtained, there is variation in the edge effect in the circumferential direction and width direction of the tire. This can cause skidding, especially when turning,
The overall driving feeling cannot be said to be good. In addition, for those with slope size, the combination of tread pattern and ground pressure in the seven optimal conditions contributes to improving running performance and driving feeling, but depending on the pattern, performance and driving feeling may not be improved. There was a problem that it was difficult to see and lacked versatility.

(Problem to be solved by the invention) It is possible to improve traction and brake performance by reducing variations in the edge effect in the circumferential direction and width direction of tires caused by the heavy use of sipes. It is an object of the present invention to propose a new studless pneumatic radial tire that can not only improve the performance of the vehicle but also further improve the overall driving feeling.

(Means for Solving the Problems) This invention provides at least one carcass layer extending at an angle of substantially 90° to the equatorial plane of the tire and intersecting each other at a relatively small angle to the equatorial plane of the tire. A pneumatic tire comprising at least two belt layers extending in a direction such that the pneumatic tire has a groove on the tread of the tire and a plurality of blocks partitioned by the groove, each of the blocks having at least three intersection points. This is a studless pneumatic radial tire characterized by having notches that divide the block into a large number of sub-blocks and having a negative rate of 30 to 50%.

In the present invention, in the above configuration, it is preferable that the cut in the block is substantially straight.

Furthermore, it is particularly advantageous for the incisions in the block to be made up of longitudinal sipes extending substantially along the circumference of the tread and lateral sipes extending substantially along the width of the tread. Furthermore, in the present invention, a small hole with a diameter of 2 mm or less is provided at at least one of the intersections formed by the cuts. The cuts that divide the block into multiple sub-blocks are arranged in multiple cuts, and the cuts that extend in the same direction are parallel to each other. The incisions that divide the block into a plurality of subblocks shall consist of at least two types of incisions with mutually different directions, and these incisions shall have different numbers of incisions. Forming incisions in mutually adjacent blocks along the width of the tread in which the arrangement of the blocks is opposite to each other. The cuts that divide the block into a plurality of sub-blocks are made of at least two types with mutually different directions,
Each of these cuts shall have a radius of curvature. A cut with a small number of cuts has a wider cut width than a cut with a large number of cuts. The horizontal sipe extending along the width of the trend has a longer cutting length than the vertical sipe. The blocks in the central area of the tread have more lateral sipes than the blocks in the sides. At least two horizontal sipes extending along the width of the tread shall be arranged in the same block. At least two vertical sipes extending along the circumference of the tread shall be arranged in the same block. The number of horizontal sipes extending along the width of the tread is greater than the number of vertical sipes within the same block. The longitudinal sipes are substantially parallel to the equator of the tire; - the impulse sipes are perpendicular to the equator of the tire. The lateral sipes shall have at least one bend. It is especially convenient for at least one end of the cut of the horizontal sipe to be communicated with the groove portion of the vertical sipe formed within the same block. Note that the above-mentioned fir sipes and horizontal sipes are not limited to those composed of straight lines (they may be zigzag, or sine curves that change with a certain amplitude, or can be changed as necessary, such as a curve with a relatively small degree of curvature.

Now, Fig. 1 shows that the tire is substantially 90° to the equatorial plane of the tire.
at least one carcass layer extending at an angle of;
This invention comprises at least two belt layers (the structure of the tire is similar to a normal radial tire and is not shown here) extending in directions that intersect with each other at a relatively small angle with respect to the equatorial plane of the tire. In the figure, number 1 is a groove provided in the tread T of the tire, 2 is a plurality of blocks partitioned by this groove 1, and 3 is a notch, and this notch 3 is the circumference of the tread T. It is preferable to have a reduced sipe 3a extending along the width of the tread T and a lateral sipe 3b extending along the width of the tread T, forming at least three intersection points p in the block 2 to divide the block into a large number of sub-blocks 2a. . In order to achieve both performance on ice and snow as a studless tire, the tire with the above structure has a residual area calculated by subtracting the total area of the blocks 2 in that area from the area of the contact area of the tread T. The negative rate given as a percentage is set in the range of 30 to 50%.

(Function) The notches 3 formed in the block 2 serve as the edge component of the tire, so the more of them there are, the stronger the edge effect can be exerted, but the more they are, the more they will reduce the rigidity of the block. Therefore, there is a limit to how many cuts can be made.

Usually, depending on the tread rubber and the size of the block, there are usually about 2 to 5 pieces per block in a single direction. In addition, the edge effect due to cuts is determined by the way the cuts are made, so if there are multiple cuts in the same direction, a strong edge effect will be exerted only in that direction. A balanced edge effect cannot be expected. In this invention, the blocks 2 are made with cuts in mutually different directions.
The tread T is provided within a range that does not cause deterioration of block rigidity.
In addition to increasing the edge component along the circumference of the tread T, we also increased the edge component along the width of the tread T, which not only balances the edge effect and improves traction and braking performance, but also improves the overall The driving feeling will also be advantageously improved.

It is advantageous for each sipe to have a long cut length, and for this purpose, it is preferable that the sipes intersect with each other.

In this invention, at least three intersection points P are formed by cuts in different directions, that is, vertical sipes 3a and horizontal sipes 3b, because if the number of intersections p is smaller than this, it is not possible to obtain the expected edge effect. For example, there are 3 horizontal sipes 3b that serve as edge components that help improve traction and braking performance, and 3 vertical sipes that serve as edge components that help improve cornering performance.
If one a is provided, there will be three intersections p.

In FIG. 1 above, there are two substantially straight cuts arranged parallel to each other along the circumference of the tread.
Furthermore, an example is shown in which two cuts are similarly provided in a direction along the width of the tread intersecting with the width of the tread.

Fig. 2 shows an example in which the block 2 is provided with one vertical sipe 3a and three horizontal sipes 3b arranged parallel to each other, but in this case, the edge effect in the lateral direction of the tire may be somewhat alleviated. It is particularly advantageous in such cases.

In FIG. 3, two vertical sipes 3a substantially parallel to the equator of the tire and two horizontal sipes 3b orthogonal to the Burmese sipes 3a are provided, and at least the intersection point p formed by these is provided. An example is shown in which a small hole with a diameter of 2 or less is provided in one. By providing such a small hole, melt water on an icy road surface can be sucked into the small TL b, thereby improving driving performance on ice.

In this invention, the diameter of the small hole is set to 2 mm or less, but this is because setting the diameter of the small hole to 2 mm or less may reduce the rigidity of the block or reduce its effective ground contact area. This is because there is no disadvantage of making the hole smaller, and furthermore, the small hole is of a size that can be machined.

Next, FIG. 4 shows an example in which cuts 3 are formed in each of blocks 2 adjacent to each other along the width of the tread T, with incisions 3 having opposite arrangements between the blocks. Tires with such a tread pattern have different numbers of sipe cuts in one block, upward to the right and upward to the left, but the bias in the edge component due to the sipes is extremely small when looking at the tread as a whole.

Next, FIG. 5 shows an example in which two sipes rising to the right and two sipes rising to the left are respectively curved to form four intersection points p. In a tire with such a pattern, each of the sipes is cut along the outer contour of the block 2, so that the sub-blocks 2a partitioned by this can be made to have almost the same size, resulting in unevenness. It can be expected to prevent wear.

Here, in this invention, it is effective from the viewpoint of ensuring appropriate rigidity that among the cuts 3 formed in the block 2, the cuts with a small number have a larger width than the cuts with a large number, For example, as shown in FIG. 6, a plurality of horizontal sipes 3b are provided,
When this width is about 0.7 mm, the width of the vertical sipe 3a, which has fewer cuts than the horizontal sipe 3b, is approximately 1
．． It is preferable to set it to about 5 mm.

Figure 7 shows that the block 2 in the central area of the tread has more lateral sipes 3b than the blocks in both side areas.
This is an example of forming a . Tread center area Tc with high ground pressure
By using many horizontal sipes 3b in block 1,
Brake performance and Traction Bonn performance can be further improved. In addition, by providing many vertical sipes 3a in the blocks 2 at both end regions of the tread, side slip during cornering can be avoided and cornering performance can be advantageously improved.

Figure 8 shows the case where a bending point C is provided on the horizontal sipe 3b.By providing the bending point C on the horizontal sipe in this way, the edge component due to the horizontal sipe 3b in the block is made uniform as a whole. This improves straight-line stability when driving. Here, the bending point C overlaps the intersection p.

Next, FIG. 9 shows an example in which at least one end of the cut in the horizontal sipe 3b is communicated with the groove portion of the vertical sipe 3a. By arranging the horizontal sipes 3b alternately in the circumferential direction of the tread with the vertical sipes 3a in between, the input from the road surface of the tire can be alleviated and the wear resistance can be improved. There are advantages that can be achieved.

Figure 10 shows an example in which the right-sloping sipe and the left-sloping sipe each have an angle of about 35'' with respect to the axis of rotation of the tire.By making each sipe an inclined sipe in this way, when the tire rotates, It is possible to alleviate the human force on the road surface, which in turn suppresses block collapse and improves wear resistance.In addition, in order to ensure appropriate block rigidity, the above cuts are made on the ground contact surface in order to ensure appropriate block rigidity. It is important that the distance is such that the wall surfaces come into contact with each other, and specifically, it is preferably about 0.5 to 1 mm.

In this invention, it is preferable that the sipes extending in the same direction be cut approximately parallel to each other in order to prevent deterioration of block rigidity. Furthermore, the cut length of the horizontal sipes 3b is preferably longer than the cut length of the vertical sipes 3a, since braking performance and driving performance are particularly important during normal driving.

(Example) A tire of size 185/70R13 having a pattern as shown in FIG. 1 above, a tread width of 14011Ill and a negative rate of 40%, and a tire with a pattern as shown in FIGS. 11 and 12. Comparison tires 1 and 2, which are identical except for
We investigated Traxidin, brakes, and driving feel on ice. The results are shown in Table-1.

In addition, on-snow traction measures the driving force on a compacted snow road surface using an instrument, while on-snow feeling is the overall feeling of starting, turning, climbing, and braking on a circuit course with a compacted snow road surface. The braking distance from 40 h/h was measured, and the feeling on ice was evaluated based on the feeling of turning ability on an icy road surface.

Table 1 (Effects of the Invention) Thus, according to the present invention, even if a large number of sipes are used to improve running performance on snow or ice, the edge effect along the circumference of the tread and the edge effect along the width direction of the tread can be reduced. Since there is no large difference in the driving performance, it is possible to advantageously improve the overall driving feeling in addition to improving the driving performance.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a studless pneumatic radial tire according to the present invention. FIGS. 2 to 10 are diagrams showing other examples of tires according to the present invention. FIGS. 11 and 12 are treads of comparative tires. It is a figure showing a pattern. 1...Groove portion 1b...Horizontal groove 2a...Sub block 3a...Vertical sipe T...Tread b...Small hole C...Bending point 1a...Vertical groove 2...Block 3... Notch 3b... Lateral sipe P... Intersection Tc... Tread center area Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 - Fig. 8 Fig. 9 Figure 1O Figure 11 Figure 12

Claims (1)

[Claims] 1. at least one carcass layer extending at an angle of substantially 90° to the equatorial plane of the tire; and at least two belt layers extending transversely to each other at a relatively small angle to the equatorial plane of the tire; A pneumatic tire having a groove on the tread of the tire and a plurality of blocks partitioned by the groove, each of the blocks having at least three notches forming intersections to divide the block into a number of sub-blocks. , a studless pneumatic radial tire characterized by a negative rate of 30 to 50%.