KR20040005444A - Radial tire - Google Patents

Abstract

PURPOSE: A pneumatic radial tire is provided to make a third circular arc of the tire forming a tread profile into a straight line of an infinite curvature radius with a minimum flatness and three circular arcs and to obtain an optimal tread. CONSTITUTION: An in-mold for a radial tire for a vehicle has a minimum flatness of 30¯55 and forms a tread profile with first, second, and third circular arcs(TW1,TW2,TW3). The length of the second circular arc forming the curvature of a tread(7) having a symmetrical profile at a section of a pneumatic pressure non-applied tire is 1.0¯2.0 times as long as the length of the first circular arc. The length of the third circular arc is below 0.75 times of the second circular arc. A first curvature radius(TR1) of the first circular arc is within 1.5¯2.5 times of a second curvature radius(TR2) of the second circular arc. A third curvature radius(TR3) of the third circular arc is infinite.

Description

Pneumatic Radial Tires

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire of an automobile. In particular, in a tire that forms a tread using three arcs, a third tread arc of three arcs is formed to have a straight line having an infinite radius so as to improve tire grip. Therefore, the present invention relates to a vehicle pneumatic radial tire capable of improving steering stability and braking performance while driving a vehicle.

Due to the performance improvement of passenger cars, many high-performance and high-power vehicles have appeared. It is understood that tires used in such vehicles generally have low flatness ratios, and that extremely low flatness tires are used in high-performance vehicles, and thus use conditions are very harsh.

At this time, the flat ratio means the ratio of the tire cross-sectional height to the tire cross-sectional width and is calculated by the following formula.

By using the flat ratio value of the tire calculated by the above equation, the type of tire will be referred to by the name of 60 series (when the flat ratio is 60%) or the like.

The tread profile of the tire is formed to have a predetermined curvature, but this is achieved by successive circular arcs formed with different curvatures instead of a single curvature.

At this time, a tire having a large flat ratio is generally formed by only two circular arcs having different curvatures. However, a tire having a very low flat ratio such as a 30 series to 55 series tire has a relatively wide tread width, so only two circular arcs are used to ground the tire. There was a difficulty in implementing the shape.

Therefore, it is desirable to set the tread profile using three arcs to achieve a ground shape that meets the target performance.

When designing the tread profile of a tire using three arcs, it is common to design so that the radius of a circular arc may become small toward the shoulder side of a tire.

That is, in the design of the tire as described above, in order to obtain the effect of improving the steering stability, the braking performance, and the abrasion of the tire, the shape of the tire's ground part is generally formed in a curvature shape. It is preferred that it is formed to have a uniform ground pressure distribution.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a cross-sectional shape of an in-mold of a pneumatic radial tire according to the prior art. The first circular arc TW1 and the second circular arc TW2 have an extremely low flat ratio of 30 to 55. And an in-mold cross section of a pneumatic radial tire which forms a tread profile using the third circular arc TW3.

First, as shown in FIG. 1, the pneumatic radial tire is attached to the outer surface of the inner liner 1 and the inner liner 1 which form the inner surface of the tire, and both front end portions of the pneumatic radial tire are respectively bead 3 and bead filler. (4) a pair of carcasses (2), a pair of beads (3) and bead fillers (4), which are wrapped around the tip of the carcass (2) and the outer surface of the carcass (2), respectively, oppositely attached The side wall 5 and the central part are attached to the outer surface of the carcass 2, and both ends are attached to the outer surface of the pair of side walls 5, respectively, and the central part is the outer surface of the belt 6. Both ends are attached to the structure is composed of a tread (7) attached to each of the outer surface of the pair of side walls (5).

At this time, it is shown that the first arc TW1, the second arc TW2 and the third arc TW3 constituting the tread 7 are formed with respective curvature radii TR1, TR2, TR3.

When the tire is manufactured using the in-mold as described above, the tread profile of the tire is changed by the deformation of the material during the manufacturing process. When the tread profile is designed using three arcs, the change amount is larger toward the shoulder of the tire. There was a problem that the angular ground shape than the target ground shape due to the tread arc ratio intended at the time.

An object of the present invention is a tire completed by forming a third circular arc of a pneumatic radial tire having an ultra-low flat ratio and forming a tread profile using three circular arcs to form a straight line having an infinite curvature in order to solve the problems as described above. It is an object of the present invention to provide a pneumatic radial tire that allows to obtain an optimum ground shape when using the.

1 is an in-mold cross-sectional view of a pneumatic radial tire according to the prior art.

Figure 2 is an in-mold cross-sectional view of one embodiment of a pneumatic radial tire according to the present invention.

Explanation of symbols on the main parts of the drawings

1: Inner Liner 2: Carcass

3: bead 4: bead filler

5: sidewall 6: belt

7: tread

Hereinafter, the technical configuration of the present invention with reference to the accompanying drawings in detail.

Figure 2 is a cross-sectional view of one embodiment of a pneumatic radial tire according to the present invention.

First, a pneumatic radial tire as shown in FIG. 2 is an innerliner 1, a carcass 2, a bead 3 and a bead filler 4, a pair of sidewalls 5, a belt ( 6) What consists of the treads 7 is the same as that of the prior art.

First, in the case of the radial tire according to the present invention, the tread 7 is formed symmetrically with respect to the center line of the tire, and each tread 7 uses first, second and third arcs TW1, TW2, and TW3. It is formed.

FIG. 2 is a radial vehicle used in a small load vehicle such as a passenger car having an ultra-low ratio of 30 to 55 and having a tread mold profile symmetrically formed using first, second and third arcs TW1, TW2 and TW3. In the in-mold for a tire, the length of the second arc TW2 constituting the curvature of the tread 7 whose profile of the tread 7 is symmetrical on the tire cross section before the pneumatic action is the length of the first arc TW1. 1.0 to 2.0 times, and the length of the third arc (TW3) is formed less than 0.75 times the length of the second arc (TW3), the radius of curvature (TR1) of the first arc (TW1) is the second arc Pneumatic radial tires are shown which are in the range of 1.5 times to 2.5 times the radius of curvature TR2 of TW2, and the radius of curvature TR3 of the third arc TW3 is ∞.

Referring to the drawings, a preferred embodiment of the present invention will be described.

In the case of a radial tire having an extremely low flatness ratio, it is common to form a tread profile of a tire using three arcs. In order to improve the steering stability of the tire and to improve the braking performance, it is preferable that the ground shape of the tire form a curved surface as a whole, but the center portion has a long ground field and a uniform ground pressure distribution as a whole.

In order to have a uniform ground pressure as described above, the mold profile of the radial tire is formed as follows.

In preparation, the maximum tire diameter, the maximum cross-sectional width of the tire, and the cross-sectional width of the tread profile are determined.

First, the first circular arc TW1 starting from the cross-sectional center line of the radial tire is formed, and the second circular arc TW2 is formed continuously to the first circular arc TW1.

At this time, it is preferable that the length of the second circular arc TW2 satisfies the range of 1.0 to a maximum of 2.0 times the length of the first circular arc TW1. In addition, the radius of curvature TR1 of the first arc TW1 may be 1.5 to 2.5 times the radius of curvature TR2 of the second arc TW2.

After the first arc TW1 and the second arc TW2 are formed, the third arc TW3 is formed continuously to the second arc TW2. At this time, the length of the third circular arc TW3 is formed to be within the range of 0.75 times the length of the second circular arc TW2.

The curvature of the third circular arc TW3 which is formed continuously to the second circular arc TW2 is set to be ∞. That is, the third circular arc TW3 is formed in a straight line shape.

The first, second and third circular arcs TW1, TW2, TW3, which form the curvature of the tread in which the mold profile of the tread 1 is symmetrical, are formed to a predetermined length value. In this case, the length ratio TW1: TW2 of the first arc TW1 and the second arc TW2 may be formed to satisfy a range of at least 1.0 to at most 2.0. In other words, the value of TW2 / TW1 is in the range of 1-2.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be carried out without departing from the spirit.

According to the present invention configured as described above, in the tread mold profile of the radial tire composed of three circular arcs, the circular shape of the radial tire farthest from the cross-sectional center of the radial tire is formed in a straight line so that the ground shape of the radial tire completed as a whole is curved. The central part has a long grounding field and a uniform ground pressure distribution as a whole, thereby improving the steering performance, braking performance, and suppressing water film production of the tire.

Claims (1)

In the in-mold for radial tires used in small-load vehicles, such as passenger cars having a very low ratio of 30 to 55 and a tread profile is formed using the first, second and third arcs (TW1, TW2, TW3), The length of the second circular arc TW2 constituting the curvature of the tread whose in-mold profile of the tread is symmetrical on the tire cross-section before pneumatic action is formed to be 1.0 times to 2.0 times the length of the first circular arc TW1, and the third circular arc The length of the TW3 is less than 0.75 times the length of the second arc TW3, and the radius of curvature TR1 of the first arc TW1 is 1.5 times the radius of curvature TR2 of the second arc TW2. In the range of 2.5 to 2.5 times, wherein the radius of curvature TR3 of the third arc TW3 is configured to be ∞.