JPS63315303A - Studless tire excellent in on-ice performance - Google Patents

Abstract

PURPOSE:To increase the ground-connected area of a tire so as to improve its brake performance on ice by setting a width in a bead part to a specific proportion for the width of a tread part while a position of the maximum width part of the tire to a specific proportion of its height from the end of the tread part. CONSTITUTION:A tire is equipped with a pair of right and left bead parts 4, right and left paired side parts 3 continued to each bead part 4 and a tread part 1 crossing across between each side part 3. Here the tire, when assumed (b) for width of the bead part 4 further (a) for width of the tread part 1, forms a relation where b=0.5-0.9a to be set. While the tire, when assumed (h) for height of the tire further l for space from the end of the tread part to the maximum width part of the tire, sets a relation where l=0-0.42h. That is, the bead part 4 sets its width (b) to a range 50-90% the width (a) of the tread part 1. While a position of the maximum width part of the tire is set to a range 0-42% tire height from the end of the tread part. In this way, the tire easily further surely increases its grounded area.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a studless tire particularly suitable for use on icy road surfaces, and is intended to improve its braking performance on ice.

Spiked tires have been used on ice and snowy roads, but since spike pins can cause severe damage to snow-removed roads and road markings on roads, the use of so-called studless tires, which can be used without spike pins even on ice, is recommended. ing.

(Prior art) Studless tires have a shape similar to general-purpose tires, and their performance on ice and snow has been improved primarily by improving the tread rubber and tread pattern.

(Problems to be Solved by the Invention) Although various performance improvements have been achieved through the above-mentioned improvements, the braking performance, especially on ice, is still inferior to that of spiked tires. For example, test results by the Japan Tire Association show that spiked tires If the braking performance on ice is 100, studless tires have a rating of 76, and there is a strong demand for improvement from a safety perspective.

Therefore, it is an object of the present invention to improve the braking performance of a studless tire on ice by a method other than improving the tread rubber or tread pattern, thereby providing a highly safe studless tire.

(Means for Solving the Problems) This invention has a pair of left and right bead parts, a pair of side parts connected to each bead part, and a tread part spanning between both side parts, and has a width a1 side of the tread part. This is a studless tire with excellent on-ice performance, in which the width of the bead portion and the width C of the bead portion satisfy the relationship a>b>c.

In the studless tire of the present invention, the width C of the bead portion is set in a range of 50 to 90% of the width a of the tread portion;
Position the maximum width of the tire at 1 tire height from the tread edge.
It is recommended as an embodiment to set it in the range of 0 to 25%.

Now, FIG. 1 shows a sectional view of a studless tire according to the present invention, and the carcass and belt structure are the same as those of a normal radial tire, and illustration thereof is omitted.

In the figure, 1 is the tread part, 2 is a shoulder part, 3 is a side part, 4 is a bead part, a is the tread part 10 width, and b
is the width between the side parts 3, C is the width between the bead parts 4, W is the tire maximum width, h is the tire height, and l is the distance from the tread edge to the tire maximum width part P.

In the illustrated studless tire, the shape when filled with normal internal pressure satisfies the following conditions.

W≧a>b>c... (1) c=0.5
~0.9 a −= (2)! =0.1
~0.25 h... (3) Here, the above equation (1) gives a shape in which the tread width is larger than the side part spacing and the air-filled volume of the tire is reduced. In the above equation (2), the bead interval C is 0.
．． The reason for setting the value to 5 to 0.9a is that the shape within this range can effectively reduce the air volume, that is, reduce the belt tension.

Furthermore, the distance l between the tread edge and the maximum width of the tire is 0.1
The reason for ~0.25h was originally R= 0 ++t+n
is desirable, but it is impossible due to tire manufacturing, so β-0.1 ~
0.25h is the minimum margin possible in manufacturing.

The structure of the tire is usually the same as that of a radial tire; for example, a carcass with one or two layers reinforced with a steel belt or textile belt is suitable, and the tread pattern follows that of a conventional studless tire. do.

(Function) Braking performance on ice depends on the tread rubber quality and tread pattern, and improves as the contact area of the tread increases. For example, it has been confirmed that when the ground contact area increases by 10%, the braking performance also improves by 10%, that is, the stopping distance after applying the brakes becomes 10% shorter.

As shown in Figure 2, in the case of normal radial tires, simply increasing the tread width also increases the maximum tire width, and as the internal volume of the tire increases, the belt tension also increases, so the tread width is larger than the width of the tire side part. With conventional small tire shapes, there is a limit to how much ground contact area can be increased.

Therefore, in this invention, as shown in Fig. 1, the tread width is made larger than the tire side width, and the air filling volume is made smaller compared to the conventional tire shape, thereby reducing the belt tension and thereby significantly increasing the ground contact area. Improves braking performance on ice.

Here, when the tire load is the same, an increase in the ground contact area means that the average contact pressure with the road surface per unit area of the tire contact patch is smaller.

As shown in FIG. 3, the friction coefficient μ of rubber on ice increases as the contact pressure decreases, unlike metals. Figure 3 shows 1655R13 studless tires (internal pressure 1.
7 kg/cm2) at an ice temperature of -10°C.

By utilizing the characteristics of this rubber, braking performance on ice can be improved by increasing the ground contact area. Therefore, even if the tire tread width is increased, the air-filled volume of the tire will not increase much, and therefore the belt tension will not increase ( Decrease),
We achieved an increase in ground contact area using the new tire shape shown in Figure 1.

(Example) A tire with the shape shown in Figure 1 was prototyped with the specifications shown in Table 1, and the braking performance on ice was evaluated using the coefficient of friction on ice. The results are shown in Table 2 in comparison with the conventional example. show. As a conventional example, tire size 165/82 R14 (82
”), 185/70 R14 (70”) and 19
A 5/60 R15 (60") tire was used, the tread rubber quality and tread pattern were the same for both the prototype tire and the conventional tire, and the load was 350 kg.

Table 1 From Table 2, the prototype tire according to the present invention has an increased ground contact width,
On the other hand, the belt tension decreases due to the decrease in air filling volume.
Therefore, the contact area is 10% compared to a 70" tire.
It can be seen that μ on ice also increases by 10%.

(Effects of the Invention) In the studless tire of the present invention, even if the width of the tread portion is increased, the increase in the air bubble volume is extremely small, and an increase in belt tension can be avoided, thereby increasing the ground contact area, thereby improving braking on ice. It is possible to provide tires with excellent performance.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a studless tire according to the present invention, Fig. 2 is a graph showing the relationship between tread width, belt tension, and ground contact area, and Fig. 3 is a graph showing the relationship between contact pressure and coefficient of friction on ice. be. 1...Tread part 2...Shoulder part 3...
・Side part 4...Bead part Figure 2 Figure 3 Procedural amendment 632Iδ Director General of the Japan Patent Office Kunio Ogawa 1, Indication of case Patent application No. 151520 of 1988 2, Title of the Invention: Studless Tire 3 with Excellent Performance on Ice; Relationship with the Amendment Case Patent applicant (527) Brideston Co., Ltd. 4, Attorney 1, amends the scope of claims in the specification as follows. ``2. Claim 1: A vehicle that has a pair of left and right bead portions, a pair of side portions connected to each bead portion, and a tread portion extending between both side portions, and has excellent on-ice performance. 2. Tread section on page 3, lines 1 to 9 of the specification.
...Recommended. ” is corrected as follows. The width of the bead part is set in the range of 50 to 90% of the width of the tread part, and the position of the maximum width part of the tire is set in the range of 0 to 42% of the tire height from the tread edge. It is a studless tire with excellent on-ice performance.'' 3, page 3, line 15, ``Width between side parts 3, C
Delete ``ha''. 4. In the 4th sentence, lines 2 to 16, ``Ki... desu'' is corrected as follows. "Note b = 0.5 ~ 0.9a = (1) ! = 0 ~ 0.42h (2) Here,
In the above formula (1), the bead part spacing is 0.5 to 0.
9a because the shape within this range can effectively reduce the air volume, that is, reduce the belt tension. ” 5, page 5, lines 13 to 17, “
"Tension and shape" should be corrected as follows. "The tension also increases. Therefore, in this invention, the shape is as shown in Figure 1, and the shape of the tire is different from the conventional tire shape." 6. Figure 1 is corrected as shown in the attached sheet.

Claims (1)

[Claims] 1. A tread portion comprising a pair of left and right bead portions, a pair of side portions connected to each bead portion, and a tread portion spanning between both side portions, the width a of the tread portion, the width b of the side portion, and the width b of the side portion. A studless tire with excellent on-ice performance, in which the width c of the bead portion satisfies the relationship a>b>c.