KR20040005445A - Tread profile design method in radial tire - Google Patents

Abstract

PURPOSE: A method for designing a tread profile of a pneumatic radial tire is provided to set end points of each circular arc forming the tread profile in a tread mold profile as a coordinate value and then form three circular arcs by connecting end points and accordingly to improve braking performance and driving stability by designing the tire having a uniform tread. CONSTITUTION: An X axis value(X1) of an end point(A) of a first circular arc(TW1) is in the 7¯10 % of total tread width, an X axis value(X2) of an end point(B) of a second circular arc(TW2) is within 30¯40 % of the total tread width, and an X axis value(X3) of an end point(C) of a third circular arc(TW3) is 49.5% of the total tread width. Y axis value of each circular arc is calculated by Y(n)=aX(0.2XTW+S.H). The 'a' is 0.1¯0.3%, 1.5¯2.0%, and 7¯9% at Y axis values(Y1,Y2,Y3) of first, second, and third circular arcs, respectively.

Description

Tread profile design method in radial tire

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire of an automobile, and in particular, in a tire forming a tread using three circular arcs in a tire manufacturing process, a point design concept is applied to a tread profile design concept to coordinate the end points of each arc. Where the x-axis value is the ratio of the arc and the y-axis value is expressed as a formula for the arc and the cross-sectional height.

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.

In this case, 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 wide tread width, so that only two circular arcs are used to target 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 embodiment of a pneumatic radial tire according to the prior art, wherein the first circular arc TW1, the second circular arc TW2, and the third circular arc have an extremely low flat ratio of 30 to 55. The cross-sectional shape of the pneumatic radial tire which forms the tread profile using (TW3) is shown.

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 and TR3.

In setting the tread profile using three arcs, each arc is set at a constant ratio with respect to the overall tread width, and the curvature of the arc is set at a constant ratio with respect to the cross section width.

However, since the tire's grounding shape and grounding pressure are different depending on the size change of the arc and the cross-sectional height change, the existing design method causes failure of the target grounding shape and uneven grounding pressure, resulting in overall performance degradation. There was a problem.

An object of the present invention is to coordinate the end point of each arc constituting the tread profile in designing a pneumatic radial tire having an ultra-low flat ratio and forming a tread profile using three arcs in order to solve the problems as described above. Set the tread profile of pneumatic radial tires so that the X coordinate of the end point is set as a percentage of the overall width of the tread and the Y coordinate is set to a value for the total width of the tread and the section height (SH). It aims to do it.

1 is a cross-sectional view of one embodiment of a pneumatic radial tire according to the prior art;

2 is a cross-sectional view of a tire for explaining a design method 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.

2 is a cross-sectional view of a tire for explaining a design method 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.

As shown in the figure, it is used in a small load vehicle having an ultra-low ratio of 30 to 55 and having a tread mold profile symmetrically formed using the first, second and third arcs TW1, TW2 and TW3. In the radial tire, the X-axis value X1 of the end point A of the first arc TW1 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 total The X axis value (X2) of the end point (B) of the second arc (TW2) is in the range of 30 to 40% of the total tread width, and the third arc (TW3) The X-axis value (X3) of the end point (C) is in the 49.5% range of the overall tread width.

At this time, the Y-axis values Y1, Y2 and Y3 of the first, second and third circular arcs TW1, TW2 and TW3 are set by the following formula.

At this time, a is preferably set to 0.1 to 0.3% in Y1, 1.5 to 2.0% in Y2, and 7 to 9% in Y3. These a values are empirical values obtained from various experiments.

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 grounding pressure as described above, the radial tire tread is formed as follows.

In preparation, the tire maximum diameter, tire width (TW) and the section height (SH) of the tread profile are determined. In the embodiment of the present invention, the tire minimum section width is 205 mm.

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.

When the coordinate value of the cross-section center O where the first circular arc TW1 starts is (X0, Y0), the coordinate values (X1, Y1) of the end point A of the first circular arc TW1 are set. . At this time, X1 is in the range of 7 ~ 10% of the total tread width, Y1 is calculated using the above [Equation 2].

After the coordinate values X1 and Y1 of A are set, a line is connected to A from the cross-sectional center position of the radial tire to form the first arc TW1.

In setting the coordinate values (X2, Y2) of the end point (B) of the second circular arc (TW2), X2 is in the range of 30 to 40% of the overall tread width, Y2 is expressed by using Equation 2 Calculate

After the coordinate values X2 and Y2 of the end point B of the second circular arc TW2 are set, the second circular arc TW2 is constructed by connecting A and B.

In setting the coordinate values X3 and Y3 of the end point C of the third circular arc TW3, X3 is positioned at 49.5% of the overall tread width, and Y3 is calculated using Equation 2 above.

After the coordinate values X3 and Y3 of the end point C of the third circular arc TW3 are set, the third circular arc TW3 is constructed by connecting B and C.

By the above method, the coordinates of the end points of the first, second and third arcs TW1, TW2 and TW3 are set to connect the end points to each other to form three arcs forming the tread profile of the tire. .

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 arcs, the end points of the arcs forming the tread profile of the radial tire are set as coordinate values, and then the respective end points are connected. By designing three circular arcs to design a tire having a uniform ground shape as a whole, it has the effects of improving braking performance, steering stability, abrasion performance, and suppressing water film formation.

Claims (1)

In the radial tire design method used in a small load vehicle having an ultra-low ratio of 30 to 55 and the tread mold profile is formed symmetrically using the first, second and third circular arcs (TW1, TW2, TW3), The X-axis value X1 of the end point A of the first circular arc TW1 constituting the curvature of the tread 7 whose profile of the tread 7 is symmetrical on the tire cross section before pneumatic action is 7 to 10 of the overall tread width. X axis value X2 of the end point B of the second arc TW2 is in the range of 30-40% of the total tread width, and X of the end point C of the third arc TW3. The axis value (X3) is in the 49.5% range of the overall tread width, and the Y axis value is The a tread profile design method of a pneumatic radial tire, which is calculated by a, is set to 0.1 to 0.3% in Y1, 1.5 to 2.0% in Y2, and 7 to 9% in Y3.