JPS59199308A - Pneumatic tire for icy and snowy road - Google Patents

Abstract

PURPOSE:To reduce damage of the surface of a road and a noise at the time of running on a general road, by making use of a thing formed of as a spike for laying in a tread rubber layer by coating with cover rubber having peculiarity softening a flange of the spike at a temperature of more than a predetermined one. CONSTITUTION:A spike 20 to be driven in a tread rubber layer 11 is formed of a main body 21 of the spike 20 and cover rubber 22. As for the main body 21 of the spike 20, a tip 25 is fitted in the top of a shank 23 and a flange 24 is formed on the bottom in a body. The cover rubber 22 is provided so as to cover a whole surface of a flange 24. As for a material of the cover rubber 22, a thing having peculiarity through which it becomes softer than the rubber layer 11 and cushioning characteristic is increased, though it becomes harder than the tread rubber layer 11 when a temperature of the tread rubber layer 11 is reduced at the time of running on a icy and snowy road is used.

Description

[Detailed Description of the Invention] The present invention relates to a pneumatic tire for ice and snow roads, and in particular,
By embedding spikes in the tread of a pneumatic tire, each of which has seven lunges covered with a cover rubber whose hardness has a greater temperature dependence than the tread rubber layer in both low and high temperature regions, it is possible to In addition to improving the friction performance of the road, it also reduces road damage and noise on general roads.

Generally, among the various road surfaces on which cars drive, the coefficient of friction between the tires and the road surface is the lowest when water or snow on the road surface is frozen, such as those in cold or snowy regions. The road is covered in ice and snow. Under such road surface conditions, tires tend to slip, resulting in extremely dangerous driving conditions, so various anti-skid devices or tires for icy and snowy roads have been developed.

Of these, the most commonly used are so-called spike tires, which have metal spikes protruding from the tread surface of the tire, but these spike tires have excellent friction performance on frozen and snowy roads. In addition to being superior, the tires and spikes also have the advantage of being highly durable.

However, if you drive with spiked tires on a paved road surface that is not covered with ice or snow (hereinafter referred to as a "regular road surface"),
In addition to increasing tire noise, there is a problem in that the road surface is scraped and damaged by the spikes.

This invention was made in order to solve the above problem, and the object of this invention is to provide a spike whose flange is covered with hard rubber whose hardness has a greater temperature dependence than that of the tread rubber layer. It is an object of the present invention to provide a buried pneumatic tire for icy and snowy roads, which has excellent friction performance on icy and snowy roads and reduces road damage and noise on general roads. It is about providing.

That is, as shown in the embodiments and drawings described later, the flange 24 of the spike 20 has a hardness higher than that of the tread rubber layer 11 at a temperature of 5° C. or lower, and has a hardness higher than that of the tread rubber layer 11 at a temperature of 30° C. or higher. The spikes 20 are covered with a cover rubber 22 made of a rubber material having a hardness equal to or lower than the tread rubber layer 11, and the spikes 20 are embedded in the tread rubber layer 11. This relates to pneumatic tires for icy and snowy roads.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial meridional cross-sectional view showing an embodiment of the present invention. The figure shows the tread portion 10 of the tire, and the reference numeral 11
12 is a tread rubber layer, 12 is an undertread layer, 13 is a belt layer, 14 is a carcass layer, and 15 is an inner liner. Spikes 20 are driven into the tread rubber layer 11 of the tire. The spike 20 is composed of a spike body 21 and a cover rubber 22, as shown in an enlarged view in FIG. Spike body 21
A tip 25 is fitted onto the upper end of the shank 26, and a flange 24 is formed at the lower end. The materials of the shank 26, flange 24, and tip 25 of the spike body 21 may be the same as those of conventional metal spikes, but in order to reduce road surface damage when driving on general roads other than icy and snowy roads, they are made of a material that is better than conventional materials. It may also be molded using a material with low strength.

The cover rubber 22 covers the entire surface of the flange 24 of the spike body 21.

This cover rubber 22 is attached to the flange 2 of the spike body 21.
4, but in order to further increase the durability, it is preferable to apply adhesive to the inner surface and then fit it in.

As for the material of the cover rubber 24, when the temperature of the tread rubber layer 11 of the tire decreases by 75 when driving on an icy road, the tread rubber layer 11 also becomes hard, but when the temperature of the tread rubber layer 11 decreases when driving on a general road. When the temperature rises, the tread rubber layer 11 also becomes softer, i.e., the temperature dependence of hardness
Use a thicker one.

As described above, rubber materials that have a large degree of change in hardness depending on temperature and change from higher hardness to lower hardness than tread rubber in low temperature and high temperature ranges are 1. A copolymer of styrene and a conjugated diene such as butadiene or isoprene with a relatively high styrene content, or a nor-I runene rubber (manufactured by Nippon Zeon), etc.
ZAM obtained by vulcanizing a rubber composition containing zinc oxide, stearic acid, Rikizenblack and other additives is most suitable.

Next, the snow spike of the present invention shown in FIG. 2 (example) and the spike shown in FIGS. 3 and 4 (comparative example)
We will describe the results of a performance comparison test by driving each type of tire into a tire.

The material of the spike body 21 of the Snozake 20 of this invention is the same as that of the conventional metal spike, shank diameter A = 5.5 ttan, flange diameter B = 9
tran, total length 0 = 11 mm, total flange diameter of spike 20 with flange 24 covered with cover rubber 22 D = 10 tan%a total length E = 13.5 mm, cover rubber 22 has total thickness F is 45 mm, and the thickness G below the flange of the spike body is 2.5 mm.

The snowsake shown in Figure 3 is a conventional metal spike.
Shank diameter A is 55 mm, 7 lunge diameter B; total length C
There are two types of fins, one with fins of 10 mm and 13.5 mm (Comparative Example 1) and one with fins of 9 mm and 11 mm (Comparative Example 2).

The spike shown in Fig. 4 (Comparative Example 3) is a conventional metal spike in which 3° of cushion rubber with the same diameter as the 7 flange 24 and a thickness G of 2.5 mm is glued to the bottom of the 7 flange 24. It is. The shank diameter A of this spike is 55 mm.
The flange diameter B is 10+m, the total length C is 11 cm, and the total length E when the cushion rubber 3o is glued is 13.5.
It is in.

The cover rubber of the spike of this invention and the cushion rubber of the spike of Comparative Example 3 were made of the same material and molded to the above dimensions. The compositions of the cover rubber and cushion rubber and the tread rubber layer of the tire and the blending ratios (parts by weight) of each component are as shown in Table 1.

The hardness listed in Table 1 is the value measured in each temperature atmosphere using a spring type hardness test 1pJA type according to the method specified in JT, 5Ke6301 (JI
S hardness), and the relationship between each temperature and hardness is shown in Figure 5. In FIG. 5, the solid line (a) shows the cover rubber, and the dashed line (b) shows the tread rubber layer. According to the figure, the degree of change in hardness of the cover rubber due to temperature is significantly greater than that of the red rubber layer (at -10°C
The hardness of the tread rubber layer decreases sharply between 20°C and 40°C, and at low temperatures, the hardness of the tread rubber layer is also high, but at high temperatures around 20°C, the hardness changes to lower than that of the tread rubber layer. It turns out that it does.

Table 1 * 1: N0FLSORFJX (manufactured by Nippon Zeon) 1
Mixture of 00 parts by weight and 70 parts by weight of aromatic oil *2: Styrene-butadiene rubber (Nipol 150
2 manufactured by Nippon Zeon) *3: Butadiene rubber (N1pol 1220 manufactured by Nippon Zeon) *4: N-cyclohexyl-2-benzothiazolesulfenamide performance tests were conducted on ice braking performance, ground impact performance, and durability performance. Ta. The results of each test are shown in Table 2.

The test tire is a commonly used tire for icy and snowy roads (snow tire of size 165SR13).

In the ice braking performance test and durability performance test, each spike of the test tire was made to protrude 1 inch from the tread surface.
The test was carried out by attaching 138 pieces to all wheels of a test vehicle (a four-wheeled vehicle).

In the ground impact performance test, only four spikes were arranged in a row in the width direction of the tread of the test tire, and one spike was driven in with one spike protruding from the tread surface.
I installed it only on the left front wheel of my car.

(1) Braking performance test on ice Applying sudden brakes to the front and rear wheels of a test vehicle traveling at a speed of 40 km/h on an icy road surface, the driving distance from the point where the tires are locked to the point where the test vehicle stops (braking (stopping distance) was measured. The numerical values listed in Table 2 are indexes based on the tire of Comparative Example 1 calculated using the following formula.

The above measurement was repeated five times for each test tire, and the average value was used in the calculation of the above formula.

The larger the value of this index, the higher the braking performance on ice (friction performance).
shows that it is excellent.

According to the above measurement results, although the flange diameter B of the spike body is smaller than that of the tire spikes of Comparative Examples 1 and 3, the tire of the present invention can achieve almost the same braking performance on ice. It is also seen that the tire of Comparative Example 2 has better braking performance on ice than the tire of Comparative Example 2, which has the same flange diameter as the flange diameter B of the spike body of the tire of the present invention and is equipped with spikes that are not coated with cover rubber.

This is because the tread rubber layer of the tire is cooled when driving on icy roads, and the internal temperature drops, so as the temperature drops, the cover rubber of the tire becomes harder than the tread rubber layer, and the This is because it functions as a spike with a flange of the total flange diameter, and the ground pressure increases when the spike hits the road surface.

(2) Ground impact performance test The vertical acceleration applied to the left front tire of the test vehicle traveling at a speed of 20 km/h on a general road surface was measured under the spring condition and recorded on a data recorder mounted on the test vehicle. Recorded,
The peak value was read when the spike hit the road surface.

The numerical values shown in Table 2 are indexes based on the tire of Comparative Example 1 calculated using the following formula.

The vertical acceleration of a tire occurs as a reaction to the impact when the spike hits the road surface, so by measuring the peak value of this acceleration, it is possible to estimate the degree of road surface damage caused by the spike.

For the above index, a large value indicates that the ground impact performance (road surface damage caused by spikes) is low.

According to the measurement results, the tire of the present invention has a low ground impact performance even though the total flange diameter of the spike is equal to the flange diameter B of the snow spike of the tires of Comparative Examples 1 and 3. In addition, Comparative Example 2 in which the flange diameter is the same as the flange diameter B of the spike body of the tire of the present invention and the rubber cover is not covered is installed.
It can be seen that the ground impact performance is lower than that of the tire.

This is because the tread rubber layer of the tire is heated during normal road driving and the internal temperature rises, so as the temperature rises, the cover rubber of the tires becomes softer than the tread rubber layer, and the tread rubber layer becomes softer. This is because the rubber acts as a cushion, reducing the ground pressure when the spike hits the road surface.

(3) Durability performance test on general road surface at 10. After running OOOKm, the tread surface of the tire was inspected to check whether the spikes were seated well or not, and whether or not they were falling down. The snozake was removed and the state of adhesion between the cover rubber and cushion rubber of the flange was examined.

According to the test results, the tire of the present invention is as follows: Comparative Example 1
As with the tire of Comparative Example 2, no abnormalities were observed in the way the tires were held, and the adhesion of the cover rubber to the flange of the spike body was strong, confirming that there were no problems with durability. did.

However, in the tire of Comparative Example 3, there were many spikes that did not sit well or fell down, and the cushion dome of these spikes was peeled off from the flange, and it was found that there was a problem in terms of durability performance.

Table 2 As shown above, the tire of the present invention uses spikes whose flanges are coated with hard rubber, which is made of a material whose hardness changes more rapidly with temperature than the tread rubber layer. When running on a road surface, the cover rubber becomes harder than the tread rubber layer and has the same function as the flange of the spike body. For this reason,
When the spike hits the icy and snowy road surface, the flange does not sink into the tread rubber layer, so the impact force of the tip against the icy and snowy road surface is large, making it effective as a spike with excellent friction performance. On the other hand, when the vehicle is running on a general road, the cover rubber becomes softer than the tread rubber layer, loses its function as a flange, and instead functions as a cushion. Therefore, when the spike hits the general road surface, the flange sinks into the tread rubber layer 6, so the impact force of the tip against the general road surface is reduced, and road surface damage is reduced.

The temperature conditions at the locations where the above braking performance test was conducted were -10°C at the ice braking performance test location and 12°C at the ground impact performance test location. After the above test was completed, the internal temperature of the tread rubber layer of the tire was measured near the flange of the spike, and it was -4°C in the case of the ice braking performance test and 35°C in the case of the ground impact performance test.

Separately from the above tests, the inventors measured the internal temperature of the tire tread rubber layer on icy and snowy roads and regular roads with different temperature conditions. It was found that the temperature ranged from 30°C to 50°C on ordinary road surfaces.

Therefore, regarding the temperature dependence of the hardness of the cover rubber, it becomes harder than the tread rubber layer when the internal temperature of the tread rubber layer is 5°C or lower, and when the internal temperature of the tread rubber layer is 30°C or higher. It is only necessary to select a material whose hardness is lower than that of the tread rubber layer when the hardness of the tread rubber layer increases.

The strength and hardness of the S-rubber in the examples described above satisfy the conditions for the degree of change in Table 1, but the hardness at a temperature of 30°C or higher is equivalent to that of the tread rubber layer. It is also possible to use a cover rubber such as

FIG. 6 is a partially sectional side view showing a modified example of the spike of the present invention.

Figure (a) shows the case where a recess 26 is provided on the bottom surface of the cover rubber 22, and Figure (b) shows the case where a hole 27 that penetrates the bottom surface of the cover rubber 22 is provided. This improves the cushioning function.

In the figure (c), a protrusion 24a is provided on the bottom surface of the flange 24 of the spike body 21, and the cover rubber 22 has a flange 24a.
The stability of the cover rubber 22 is increased by providing a concave portion 22a into which the convex portion 24a fits.

In the figure (d), a protrusion 24a similar to that in figure (c) is provided on the bottom surface of the flange 24 of the spike body 21, and the cover rubber 24a is provided on the bottom surface of the flange 24 of the spike body 21.
2, the convex portion 24a of the flange 24 improves fitability and cushioning function.

In the same figure (e), a concave portion 26 is provided on the bottom surface of the cover rubber 22 to cover not only the seven flange 24 of the spike body 21 but also the side surface of the shank 26, thereby improving the cushioning function and durability of the cover rubber 22. It was made more expensive.

In FIG. 2F, the cover rubber 22 is coated only on the end edge of the flange 24 of the spike body 21, so that the cover rubber 22 can be easily fitted into the flange 24.

As explained above, the tread portion of the pneumatic tire of the present invention has a hardness that is higher than the tread rubber layer at temperatures below 5°C, and a hardness equal to or lower than the tread rubber layer at temperatures above 30°C. A spike whose flange is covered with a cover rubber is buried. therefore,
In the tire of this invention, the hardness of the cover rubber of the snowsake flange changes depending on the temperature of the tire's tread rubber layer, and when driving on icy and snowy roads, the cover rubber becomes harder than the tread rubber layer, and the flange diameter increases. It functions as a key spike, and when driving on general roads, the cover rubber becomes as hard as the tread rubber layer, or softer, and functions as a cushion.

In this way, the tire spikes of the present invention provide a large impact force on icy and snowy roads, but have a small impact force on ordinary road surfaces, which are contradictory functions that cannot be expected with conventional spiked tires. It will have both.

According to the present invention, a pneumatic 9 tire for ice and snow roads has friction performance on ice and snow roads that is almost equal to or better than conventional spiked tires, reduces road damage on general roads, and produces less noise. can get.

Further, according to the present invention, since the cover rubber of Snozake covers the flange, it does not peel off from the flange even after long-term use, resulting in a tire with excellent durability.

[Brief explanation of the drawing]

FIG. 1 is a partial meridional cross-sectional view showing an embodiment of the tire of the present invention, FIG. 2 is an enlarged partial cross-sectional side view of a spike, and FIGS. 3 and 4 are a comparative example of the spike. 5 is a partial cross-sectional side view, and FIG. 6(a) is a diagram showing the degree of change in hardness of the cover rubber and tread rubber layer due to temperature.
FIGS. 6(f) to 6(f) are partially sectional side views showing modified examples of the spike. In the figure, 10 is a tread portion of the tire, 11 is a tread rubber layer, 20 is a spike, 22 is a cover rubber, and 24 is a 7-lunge. Patent Applicant Yokohama Rubber Co., Ltd. Agent Patent Attorney Tetsuya Mori Patent Attorney Yoshiaki Naito Patent Attorney Shimizu Yoshimi Kajiyama

Claims (1)

[Claims] The flange of the spike has the property that at temperatures below 5°C, the hardness of the tread rubber layer is higher, and at temperatures above 30°C, the hardness is equal to or lower than the tread rubber layer. 1. A pneumatic tire for use on icy and snowy roads, characterized in that the pneumatic tire is covered with a hard rubber made of Zam material, and the spikes are embedded in a tread rubber layer.