JPH03157208A - Pneumatic radial tire for high speed traveling - Google Patents

Abstract

PURPOSE:To expand peripheral grooves and improve drainage and block durability in very high speed traveling by forming blocks on treads with peripheral and lateral grooves, and also forming voids on side walls faced to the peripheral grooves of the blocks. CONSTITUTION:In treads, lengthwise row block groups B are divided with plural parallel peripheral grooves 1a and 1b (1), extending along a tread circumference, and many lateral grooves 2a and 2b connecting between these peripheral grooves 1a and 1b and peripheral grooves 1b and tread ends T. Moreover two rows of ribs 4, nipping auxiliary peripheral grooves s having narrower width than peripheral grooves 1, are formed on the tread middle. Each void 9 and 10 is arranged in each side wall 7 and 8 near to the tire equator O out of side walls contacting peripheral grooves 1 in each block 5 and 6 composing the lengthwise row block groups B, and thereby allowing an expanded part where volume is increased to be formed. This permits the expansion of groove volume and the achievement of an expected purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a pneumatic radial tire for passenger cars, and particularly to a flat radial tire used for ultra-high speed running.

In recent years, technological innovations in passenger cars have made it possible to drive stably at ultra-high speeds exceeding 150km/h, and along with this, cars with sufficient performance for driving at ultra-high speeds, such as those with an aspect ratio of 0.6 or less, have become possible. A flat radial tire has been developed.

(Prior Art) The tread of this type of tire has block groups defined by a plurality of relatively wide circumferential grooves along the circumference of the tire and a large number of lateral grooves connecting these circumferential grooves. In particular, the circumferential groove is provided with consideration to water drainage, has a U- or V-shaped cross-section, and extends with substantially the same width around the tread.

(Problems to be Solved by the Invention) The above-mentioned tires have sufficient performance when used in high-speed driving under -i conditions, but they do not have sufficient performance to be used in ultra-high-speed driving. It is difficult to say, but the following problems need to be solved.

In other words, flat tires with a small aspect ratio have a relatively wide tread width, so they have an excellent ability to remove the water film that covers the road surface during rain from the tire contact area (drainage performance). This is particularly important in order to avoid the dangers known as hydroplaning, aquaplaning or floating on broken roads. In addition, the tread blocks are pressed against the road surface during load transfer and generate heat, and tires for high-speed running in particular have relatively large blocks to ensure steering stability, so heat tends to accumulate in the center of the blocks. , the temperature of the block increases and blowouts are more likely to occur.

Therefore, the present invention aims to provide a pneumatic radial tire that has sufficient performance to withstand use at ultra-high speeds, that is, has both drainage performance and block durability during ultra-high speeds. be.

(Means for Solving the Problems) The inventors have studied various means for solving the above-mentioned problems and have found that drainage performance and durability of the blocks can be improved by enlarging the circumferential grooves adjacent to the blocks. I found out.

That is, the present invention combines a cylindrical crown portion and sidewall portions extending radially inward from both ends of the crown portion with a radial line extending from one sidewall portion through the crown portion to the other sidewall portion. A pneumatic radial tire reinforced with a carcass and further having a non-stretchable heald layer and a tread sequentially arranged on the radially outer side of the carcass at the crown portion, the tread having a plurality of layers extending along the tread circumference. It has a plurality of blocks partitioned by a circumferential groove and a large number of lateral grooves each extending substantially parallel across these circumferential grooves, and among the side walls of each block facing the circumferential groove, at least the side wall near the center of the tread is provided with a hole. This is a pneumatic radial tire for high-speed running.

Now, FIG. 1 shows the main part of the tread of a pneumatic radial tire according to the present invention for the left half of the tire, and the tread is made up of a plurality of substantially parallel and spaced apart parts extending along the tread circumference. circumferential groove 1a, lb
Between these circumferential grooves and by a large number of lateral grooves 2a and 2b connecting the circumferential groove 1b and the tread end T, a total of four columns of vertical block groups B are defined on the entire surface of the tread in two rows on both sides, and the circumferential block group B is divided into two rows on both sides. It is formed by dividing two rows of lips 4 sandwiching an auxiliary circumferential groove 3 narrower than the groove 1.

In the illustrated example, the circumferential groove 1 has four two-way connections on one side, but it is preferable that the circumferential groove 1 has two to four connections on one side. In addition, the lateral grooves 2a and 2b make an acute angle with the circumferential groove 1, and the equator O of the tire
It extends in a direction converging on the circumferential groove 1, and its width and depth are equal to or smaller than the circumferential groove 1.

Here, the equator of a tire refers to the circumference at the center of the tread width.

Further, among the side walls facing the circumferential groove 1 of each block 5 and 6 of the column block group B, spaces 9 and 10 are provided in the side walls 7 and 8 closer to the equator O of the tire. The groove 1 is formed with an enlarged portion whose volume is increased. The spaces 9 and 10 are formed by partially enlarging the groove width by changing the taper of the side wall of the block from the upper end of the block 5.6 toward the base. It has a shape that gradually increases from both ends toward the center.

That is, as shown in FIGS. 2(a), (b), and (C), which are cross sections taken along lines A-A, B-B, and C-C in FIG. 1, the space 9 is located in the circumferential direction of the block. The cross-sectional shape of the circumferential groove 1 is small at the ends and almost V-shaped, and then, as shown in FIG.
The volume of is expanded and the cross-sectional shape of the circumferential groove 1 approaches a quadrilateral,
The volume of space 9 reaches its maximum when it reaches the center, as shown in the same figure (C).
As shown in , the cross-sectional shape of the circumferential groove 1 is approximately a parallelogram.

It is possible to provide a void space on the other block side walls facing the circumferential groove 1, but in that case, the side wall of the block closer to the tire equator has the least influence on input from the lateral direction. It is desirable that the cavity has a smaller volume than the cavity provided on the sidewall of the tire closer to the equator. Furthermore, even if the central region of the tire with ribs arranged in the illustrated example is made into an independent block group, it is not necessary to provide a space in the side walls of these blocks.

Furthermore, the spaces provided in the side walls of the blocks do not need to be continuous in the circumferential direction as in the above example; for example, as shown in FIGS. 3(a) and 4) or FIGS. , slit-like spaces 11 or depression-like spaces 12 may be provided at equal intervals from end to end in the circumferential direction of each block.

Note that the other structure of the tire according to the present invention may be in accordance with the practice of conventional tires.

In other words, the carcass is made up of at least one turnply (3 at most) wrapped around a bead core from the inside of the tire to the outside. The belt layer is made of non-extensible cords such as steel cords and aromatic polyamide fiber cords arranged at an angle of 10 to 35 degrees to the equatorial plane of the tire. At least one layer of heat-shrinkable cord, typically a nylon cord, is arranged substantially parallel to the equatorial plane of the tire over the entire width of the main belt layer, which has at least two layers of belts arranged at an angle of . The auxiliary belt layer is formed by spirally winding a ribbon in which a plurality of cords are arranged along the circumference of the main belt layer. Then, the above-described tread is placed on this belt layer.

Furthermore, although the illustrated example shows the left half of the tread in order to have line symmetry with respect to the equator of the tire, it goes without saying that the present invention is advantageously applicable to tires with asymmetrical tread patterns.

(Function) Among the side walls facing the circumferential groove of the tire tread block,
By providing a space in the side wall near the center of the tire and forming an enlarged portion with increased volume in the circumferential groove adjacent to the block, the groove volume increases and the effect of removing water from the ground contact surface is improved.

In addition, wear within the same block is smaller as it moves closer to the center of the tire (therefore, changing the shape of the sidewall closer to the center of the tire has almost no effect on wear resistance; on the other hand, the void space promotes heat dissipation from the block. The occurrence of blowouts can be avoided without sacrificing wear resistance.

(Example) A pneumatic radial tire with a tire size of 255/40 ZR17 was manufactured as a prototype according to the tread pattern shown in FIG. 1 and the structure shown in FIG. 2. The circumferential groove of this prototype tire is width: 10 m and depth = 811111, the auxiliary circumferential groove is width: 10 + n + n and depth is near mm, and the lateral groove is width: 5
Body and depth: 1 mm and converged at an angle of 80@ to the equator of the tire, the angle between the circumferential groove 1a and the lateral groove 2a was 60'', and the angle between the circumferential groove 1b and the lateral groove 2b was 70''.

In addition, the spaces shown in FIGS. 2(a) to (C) where the angles α, β, and T are 80@, 95”, and 100e, respectively, are
Formed on the side wall of each block according to FIG.

Similarly, a tire of the same size with the tread pattern shown in Figure 1 and having no voids in the block was also prototyped.

The results of evaluating these test tires in a wear resistance test and drainage performance test, respectively, and the results of investigating the blowout occurrence speed are shown in the table below.

The test was conducted using a regular passenger car with an internal tire pressure of 2.5 kg.
/cm'' with one driver on board, and the evaluation was made using an index when each test result of the comparative tire was set as 100.

The wear resistance test was conducted at a vehicle speed of 150 km/h for 5000 km on an oval test course with a circumference of 10 km.
The drainage performance test was conducted by measuring the level difference due to wear after driving for a long time and evaluating its uniformity.The drainage performance test was conducted by measuring the lateral acceleration when cornering at a vehicle speed of 1100k/h into a 10mm deep water film on the test course. As evaluated by, the blowout onset speed is 150kph with the tire on the drum.
The speed of blowout was investigated by rotating at a speed of m/h and increasing the speed by 10km/h every 10m1n until blowout occurred, and the speed at which blowout occurred was evaluated. .

(Effects of the Invention) According to the present invention, it is possible to improve drainage performance and suppress the occurrence of blowouts even when running at ultra-high speeds without sacrificing wear resistance. We can provide suitable tires.

[Brief explanation of the drawing]

Fig. 1 is a developed view of a tread pattern according to the present invention, Figs. 2(a) to (C) are sectional views of the block side walls, Fig. 3(a) is a plan view of the block, and Fig. 3(a) is a plan view of the block. ■ of a)
Figure 4 (a) is a plan view of the block, Figure 4 (b) is a cross-sectional view of the block (
It is a sectional view taken along the line IV-IV of a). T... Tread end B... Column block group 0... Tire equator la, lb... Circumferential groove 2a, 2b.
...Horizontal groove 3...Auxiliary circumferential groove 4...Rib 5
．． 6...Block 7, 8...Side wall 9, 10
．． 11.12... Blank space Fig. 1 Fig. 3 fa) (b f a Fig. 4 (b 2

Claims (1)

[Claims] 1. A cylindrical crown portion and sidewall portions each extending radially inward from both ends of the crown portion, from one sidewall portion through the crown portion to the other sidewall portion. A pneumatic radial tire reinforced with a radial carcass extending over the entire area, and further comprising a non-stretchable belt layer and a tread sequentially arranged on the radial outside of the carcass at the crown portion, the tread extending along the tread circumference. It has a plurality of blocks partitioned by a plurality of extending circumferential grooves and a plurality of lateral grooves extending substantially parallel to each other across these circumferential grooves, and at least the side wall facing the circumferential groove of each block is located near the center of the tread. A pneumatic radial tire for high-speed running with a hollow space on the side wall.