JPH0382609A - High-performance pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce the heating of a shoulder section by gradually decreasing the thickness of a tread rubber from a tire equatorial plane to the shoulder section, and gradually increasing the value divided with the thickness of an inside rubber layer by the thickness of the tread rubber toward the shoulder section. CONSTITUTION:A cylindrical tread rubber 26 is arranged on the outside in the radial direction of the belt layer 10 and auxiliary layer 16 of a tire 1. The tread rubber 26 is located on the outside and inside in the radial direction respectively. It is formed with an outside rubber layer 27 with good abrasion resistance and an inside rubber layer 28 with low heating property. The thickness F of the tread rubber 26, i.e., the total thickness of thicknesses G and H of outside and inside rubber layers 27 and 28, is gradually decreased from a tire equatorial plane E to a shoulder section S. The value divided with the thickness H of the inside rubber layer 28 by the thickness F or the tread rubber 26 is gradually increased from the tire equatorial plane E toward the shoulder section S.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a high-performance pneumatic tire capable of running at high speeds.

Conventionally, high-performance pneumatic tires have, for example, a carcass layer, a belt layer disposed radially outward of the carcass layer, and a belt layer that covers at least both axial ends of the belt layer and extends substantially to the tire's equatorial plane. an auxiliary layer made of parallel organic fiber cords; and a tread rubber disposed radially outward of the belt layer and the auxiliary layer; An inner rubber layer is known.

However, in such conventional high-performance pneumatic tires, both the thickness of the tread rubber and the value obtained by dividing the thickness of the inner rubber layer by the thickness of the tread rubber vary from one shoulder to the other. Since the temperature is almost constant across the shoulder area, if the vehicle continues to run at high speed for a long time, both shoulder areas will generate excessive heat, and in some cases, this heat generation may cause separation at the ends of the belt layer or auxiliary layer. There is a problem.

An object of the present invention is to provide a high-performance pneumatic tire that can reduce heat generation in both shoulder portions and effectively suppress separation without deteriorating other tire performances.

This purpose is to gradually reduce the thickness of the tread rubber from the tire's equatorial plane toward the shoulder area, and
This can be achieved by gradually increasing the value obtained by dividing the thickness of the inner rubber layer by the thickness of the tread rubber from the tire equatorial plane toward the shoulder portion.

In this invention, the thickness of the tread rubber, that is, the total thickness of the inner and outer rubber layers, is gradually decreased from the tire equatorial plane toward the shoulder portion. As a result, the amount of rubber at the shoulder portion where the ends of the belt layer and the auxiliary layer are located is reduced, and therefore, even when running at high speed, the amount of heat generated at the shoulder portion is small, and the end portions of the belt layer and the auxiliary layer The separation of the two is suppressed. Furthermore, since the thickness of the tread rubber in the shoulder portion is reduced, heat dissipation is improved, and as a result, temperature rise in the shoulder portion is prevented, and separation is further suppressed. Further, in the present invention, the value obtained by dividing the thickness of the inner rubber layer by the thickness of the tread rubber is gradually increased from the tire equatorial plane toward the shoulder portion. As a result, the ratio of the inner rubber layer in the tread rubber is highest at the shoulder area, but since this inner rubber layer is made of low heat generation rubber, the amount of heat generated at the shoulder area is reduced, further suppressing separation. It is.

Todoro 1 Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Fig. 1, 1 is a high-performance pneumatic tire that can run at speeds of 200 to 350 km/h, and this tire 1 has a ratio of maximum tire cross-sectional width to tire cross-sectional height (flatness ratio) of 0.5 to 0. It is an ultra-flat tire in the range of .3. In this example, a tire with a size of 255/40ZR17 (tire with an aspect ratio of 0) is used as the tire 1. The tire 1 is reinforced with a toroidal carcass M3 extending from one bead ring 2 to the other bead ring, and both sides of this carcass layer 3 extend around the bead ring 2 from the inside in the axial direction. It is rolled up towards the outside. This carcass layer 3 is constituted by laminating at least one carcass ply 4, but not exceeding three at most, and each carcass ply 4 extends approximately in the radial direction, that is, approximately 80° with respect to the tire equatorial plane E. Intersect at degrees. Many fiber cords, typically made of rayon, polyester, nylon, etc., are buried there. In this example, 1850
Carcass ply with embedded d/2 rayon cord
Stack two pieces of 4 to form a carcass W! ! 3. 5
is a rubber filler made of hard rubber whose base end is bonded to the outer surface of the bead ring 2, and this rubber filler 5 extends radially outward from the bead ring 2 and becomes thinner toward the tip. It has a tapered shape.

A belt layer 10 is provided on the outside of the carcass layer 3 in the radial direction.
It is constructed by laminating at least two sheets, in this example, two sheets. And these belt plies 11.
The cords embedded in each of the belt plies 11 and 12 are inclined so as to intersect with the tire equatorial plane E at an angle of 15 degrees to 35 degrees, and are inclined in opposite directions and intersect with each other between the belt plies 11 and 12. In this embodiment, two belt plies 11 and 12 are provided with respect to the tire equatorial plane E.
A large number of 1x5 steel cords that intersect at 2 degrees are buried.

Reference numeral 16 denotes an auxiliary layer that covers at least both ends of the belt layer IO in the axial direction, and the auxiliary layer 1B may protrude slightly outward from both ends of the belt layer IO in the axial direction as in this embodiment. The auxiliary layer 1B, which may cover the entire layer 10, includes at least one auxiliary ply of a rubberized cord made of heat-shrinkable organic fibers such as a nylon cord (in this example, a cord made of 88 nylon). In this example, the first auxiliary ply 1 has a wide width (260 mm width) placed inside.
7, a second auxiliary ply 18 with an intermediate width (90 mm width) placed in the center, and a third auxiliary ply 18 with a narrow width (300 mm width) placed on the outside. These first, second . 3rd auxiliary ply 17゜ts
, ts are arranged substantially parallel to the tire equatorial plane E. These auxiliary plies 17.1B, 18
After arranging multiple cords (2 to 15 cords) in parallel,
These cords are rubberized to form a ribbon-like body having a width of 5 to 10 cm, and this ribbon-like body is wound spirally to form the cord. Both axially outer ends of the belt layer 10 and the auxiliary layer to are located at the shoulder portion S of the tire 1, respectively.

A cylindrical tread rubber 2B is disposed on the radially outer side of the belt layer 10 and the auxiliary layer 1B, and the outer periphery of the tread rubber 2B has a plurality of known circumferential grooves and grooves (not shown). A plurality of lateral grooves are formed extending in a direction intersecting these grooves. Said tread rubber 2
B is composed of an outer rubber layer 27 located on the radially outer side and an inner rubber layer 2B located on the radially inner side. The outer rubber layer 27 is made of rubber with good abrasion resistance and wet resistance, while the inner rubber layer 28 is made of rubber with low heat build-up, that is, rubber with a rebound coefficient of elasticity of 30% or more. Further, the thickness F of the tread rubber 2B, that is, the total thickness of the thickness G of the outer rubber layer 27 and the thickness H of the inner rubber layer 2B, almost gradually decreases from the tire equatorial plane E toward the shoulder portion S. ing. As a result, belt layer 10
The amount of rubber at the ends of the auxiliary layer 1B is reduced, the amount of heat generated is reduced, and the heat dissipation is improved, thereby preventing the temperature rise at the ends of the belt layer 10 and the auxiliary layer 1B, and separating, This suppresses the

Here, the thicknesses F, G, and H are all values measured along a perpendicular line to the belt layer 1G or the auxiliary layer 1B in the ridge portion divided by the groove.

If the thickness of the tread rubber 26 on the tire equatorial plane E is Fa, then the tread width from the tire equatorial plane E is
Thickness F of tread rubber 2B at a point 1/4 apart
b is in the range of 0.6 to 1.0 times the above Fa, and the thickness Fc of the tread rubber 2B at the shoulder portion
is preferably in a range of 0.2 to 0.6 times the thickness Fa. In this example, the thickness Fa is 10 mm,
Fb is 13mm (0.9Fa), Fc
is 5 mm (0.5 Fa).Furthermore, the value obtained by dividing the thickness H of the inner rubber layer 28 by the thickness F of the tread rubber 2B gradually increases from the tire equatorial plane E toward the shoulder portion S. As a result, the proportion of the inner rubber layer in the 2nd day tread rubber 28 is the largest at the shoulder area S;
Since this inner rubber layer is made of low heat generation rubber, the amount of heat generated at the shoulder portion S is reduced.

Separation is further suppressed. Here, contrary to the above, if the value gradually decreases toward the shoulder part S, the center part of such a high-performance pneumatic tire generally wears out before the shoulder part. There is a risk that the inner rubber calendar 28 will be exposed and the wet performance will deteriorate, or that a part of the outer rubber l1127 will be missing and chunk-out will occur. The value obtained by dividing the thickness H by the thickness F is the tire equatorial plane E.
Above, it is in the range of 0.05 to 0.25, and at a point 174 of the tread width away from the tire equatorial plane E, it is 0.
It is preferably in the range of 10 to 0.30, and in the shoulder portion S, it is preferably in the range of 0.30 to 1.0.

Further, it is more preferable that the value at the shoulder portion S is 0.50 or more. In this example, on the tire equatorial plane E, the thickness Fa is ioms, and the inner rubber layer 2
Since the thickness Ha of 8 is i, the value is 0.10, and the thickness Fb at a point 1/4 of the tread width
8-1 Thickness) Ib is 1.2mm, so the value is 0°13. Also, at the shoulder part S, the thickness Fc is 5mm, and the thickness Hc is 31mm, so the value is 0. ．．
It will be 60. As mentioned above, if the value obtained by dividing the thickness H of the inner rubber layer 28 by the thickness F of the tread rubber 2B gradually increases from the tire equatorial plane E toward the tire part S, then the inner The thickness H of the rubber layer 28 increases toward the shoulder portion S and reaches its maximum at the shoulder BS. Here, the inner rubber layer 2B has a thickness Ha in the range of 0.5 m to 2 mm on the tire equatorial plane E, and a thickness Hb of 0 at a point away from the tire equatorial plane E by 174 of the tread width. It is in the range of .5■~2.5mm, and
It is preferable that the thickness He of the shoulder portion S is in the range of 1 to 4 mm.

In this embodiment, the outer rubber layer 27 and the inner rubber fi 28 are each made of a single rubber, but they may be made of multiple types of rubber with different characteristics depending on the required characteristics of the tire l. Regarding the increase in the thickness of the inner rubber layer 28 from E to the shoulder portion S, the thickness can be increased stepwise instead of literally increasing gradually.

Next, a test example will be explained. In this test, the test tire of the above-mentioned example to which the present invention was applied was compared with the test tire in which the inner rubber layer in the test tire was a rubber sheet with a uniform thickness of 1 mm, and the other conditions were the same as the test tire. After preparing the tires, each tire was filled with an internal pressure of 2.0 Kg/Cm'' and then mounted on a passenger car, and the tires were driven for 5,000 km at a speed of 200 km/h on a circular course with a diameter of I km. Chunk-out did not occur in any of the tires, and there was no difference between the two tires.Next, each tire worn in the test was pressed against a high-speed drum while applying a load of 500 kg.

After initially driving at 1100K/h for 10 minutes, 10
Increase the speed by 10 km every minute until the final speed is 370 km/h.
km, and the high-speed durability of each tire was measured. When the results are expressed as an index, the comparison tire had an index of 100, while the test tire had an index of 130, indicating that the test tire was superior in terms of high-speed durability. Here, the index 100 is 280 per hour
It was durable up to Km.

As described above, according to the present invention, it is possible to reduce heat generation in the shoulder portion of one vehicle and effectively suppress separation without deteriorating the performance of other tires.

[Brief explanation of drawings]

FIG. 1 is a meridian cross-sectional view of a tire showing an embodiment of the present invention. ! ...High performance pneumatic tire 3...Carcass layer 10...Belt layer 1B...
・Auxiliary layer 2B...Tread rubber 27...
Outer rubber layer 2B...Inner rubber layer E...Tire equatorial plane F...Thickness of tread rubber S...Shoulder portion H...Thickness of inner rubber layer

Claims (1)

[Claims] a carcass layer, a belt layer disposed radially outward of the carcass layer, an auxiliary layer made of organic fiber cords that covers at least both axial ends of the belt layer and is substantially parallel to the tire equatorial plane, a belt layer and an auxiliary layer. a tread rubber disposed on the radially outer side of the tread rubber; an outer rubber layer having good wear resistance; an inner rubber layer having low heat generation;
In a high-performance pneumatic tire constructed of, the thickness of the tread rubber is gradually decreased from the tire equatorial plane toward the shoulder part, and the value obtained by dividing the thickness of the inner rubber layer by the tread rubber thickness is determined by the tire equatorial plane. A high-performance pneumatic tire characterized by increasing the amount gradually from the shoulder portion toward the shoulder portion.