JPS6387302A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To enhance the control stability of a tire during high speed running, by providing such an arrangement that the center section of a tire tread surface is annularly bulged out in the circumferential direction of the tire, and at least one part between the center section and a shoulder section is annularly bulged out in the circumferential direction. CONSTITUTION:The center section of the tread surface of a tire, which is around the widthwise center of the tire, is annularly bulged out in the circumferential direction of the tire, the outer surface of the bulged-out part being in a shape which is formed of a curve having a radius R1 of curvature and having its center point on the equator center line E. Further, at least one part in the intermediate area 2 between the center section 1 and a shoulder section 3 is annularly bulged out in the circumferential direction, the outer surface of the bulged-out one part being in a shape which is formed of a curve having a radius R2 of curvature. Further, the relationship between the radii of curvature R1, R2 is set so as to satisfy the following relationship: R1>R2 and, 0.2<R2/R1<=0.5. With this arrangement the grounding pressure distribution of the tread surface of the tire is made to be uniform, thereby it is possible to enhance the control stability of the tire during high speed running.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire with improved handling stability by uniformizing the ground pressure distribution on the tire tread surface.

[Prior art]

Conventionally, tires with a wide contact width on the road surface have high belt rigidity because the steel belt layer can be spread over a wide range.
Excellent limit performance during cornering. However, the ground pressure distribution on the tire tread is not uniform, and the ground pressure is lower in the middle area between the edge of the tire and the center than in other areas, which has the disadvantage of reducing maneuverability during high-speed driving. .

[Purpose of the invention]

The present invention was achieved by devising the profile of a pneumatic tire for passenger cars with a wide ground contact width, and by equalizing the ground pressure distribution on the tire tread surface, it improves driving performance during high-speed driving, especially steering stability. The purpose of the present invention is to provide a pneumatic tire with improved performance.

[Structure of the invention]

Therefore, the present invention is characterized in that the center portion of the tire tread is annularly bulged in the circumferential direction, and at least one location between the center portion and the shoulder portion is annularly bulged in the circumferential direction. This article focuses on pneumatic tires.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of the profile of the pneumatic tire of the present invention. In FIG. 1, 1 is a center portion (near the widthwise center of the tire tread surface), 3 is a shoulder portion, and 2 is an intermediate region between the center portion 1 and the shoulder portion 3.

In the present invention, the center portion 1 bulges in an annular shape in the circumferential direction. The surface shape of this bulge is formed by a curved line having a center point on the equatorial centerline E and a radius of curvature R3. A is the vertex of the curve.

In addition, in the present invention, the intermediate region 2 is small (one location in each case bulges out in an annular shape in the circumferential direction (only one location in FIG. 1),
The surface shape of this bulge is formed by a curved line with a radius of curvature R2. B is the vertex of the curve.

Regarding the radius of curvature R3 and the radius of curvature R2, it is preferable that R1>RZ and 0.2<Rz/R+≦0°5. In the case of RI≦R2, the profile of the conventional tire (Fig. 3) This is because the ground pressure distribution tends to be similar to (see (A)), and the ground pressure at the center portion decreases.

When 0.2≧Rz/Rl, in order to form the shoulder portion 3 with a smooth circular arc, the vertex B of the radius of curvature R2 will be located at the shoulder portion (the distance will be large), so as a result, The ground pressure at the shoulder part becomes high, and the ground pressure at the intermediate region 2 becomes low (so that the expected effect cannot be obtained).

When Rz /R+ > o, s, the ground pressure distribution tends to be similar to the profile of conventional tires (see Figure 3 (A)), and the shoulder part is less likely to have a round shape, which is disadvantageous in terms of wear resistance. Become.

Further, the ratio b/W of the distance from the equatorial centerline E to point B to half the ground contact width W is preferably 0.5, where Q,3<b/W. When 0.3≧b/W, the ground pressure distribution tends to be similar to the profile of a conventional tire (see Figure 2 (A)); when b/W≧0.5, the ground pressure distribution at point B increases. The effect appears in a pattern in the shoulder area, resulting in a distribution that makes the height and low of the ground pressure distribution of a conventional tire profile more pronounced.

Next, examples will be shown.

EXAMPLE The following tires were evaluated for ground pressure distribution and high-speed steering stability.

(1) Conventional tire 1° It has the profile shown in FIG. 2(A).

In other words, the ground contact area consists of a single circular arc. The grounding shape is the second
Oval shape as shown in figure (B).

In FIG. 2(B), 4 represents the tread surface.

(2) Conventional tire 2° It has the profile shown in FIG. 3(A).

In other words, it is composed of two similar circular arcs that are symmetrical about the equator center line. The ground contact shape is a cocoon ball shape as shown in Figure 3 (B).

(3) Tire of the present invention.

It has the profile shown in FIG. 4(A).

In other words, the tread consists of three arcs. The ground contact shape is a drum shape as shown in Figure 4 (B).

1 Parallel pressure standing blood test: Applying a predetermined air pressure and a predetermined overload, measuring points in the tire width direction and circumferential direction within the contact patch using a specific testing machine, and measuring the contact pressure at each point to determine the contact pressure distribution. was evaluated. The results are shown in FIGS. 5(A) to 5(C). Figure 5 (
A) shows the case of the conventional tire 1, FIG. 5(B) shows the case of the conventional tire 2, and FIG. 5(C) shows the case of the tire of the present invention. From these FIGS. 5(A) to 5(C), it can be seen that the ground contact pressure in the intermediate region of the conventional tire 1 is low (see FIG. 5(A)).
), the conventional tire 2 has low ground contact pressure in both the center and shoulder areas (Fig. 5 (B)), and there is a problem with the uniformity of the ground pressure in each area, but the tire of the present invention has low ground contact pressure in both the center and shoulder areas (Fig. It can be seen that there is almost no change in ground pressure.

i of Bundle 6: High-speed steering stability was evaluated by conducting an actual vehicle sensory evaluation at a speed of 160 to 200 km/h. The results are shown in Table 1 below using indices. The higher the value, the better. From Table 1, it can be seen that the tire of the present invention has excellent high-speed handling stability.

Table 1 Conventional tie Conventional tie Present invention [Effects of the invention] As explained above, according to the present invention, it is possible to equalize the ground contact pressure distribution on the tire tread surface and improve the motion performance during high-speed running.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the profile of the pneumatic tire of the present invention, and FIG. 2 (A). FIG. 3(A) and FIG. 4(A) are explanatory diagrams showing profiles of various tires, and FIG. 2(B). Figures 3 (B) and 4 (B) are explanatory diagrams showing the contact shapes of various tires, Figure 5 (A), Figure 5 (B), and Figure 5 (C).
) is an explanatory diagram showing the ground contact pressure distribution of various tires in a graph. l...center part, 2...middle area, 3...shoulder part, 4...tread surface. Figure 1 Figure 2 (A) Figure 2 (B) Figure 3 (A) Figure 3 (B)

Claims (1)

[Scope of Claims] Air characterized by having a center portion of a tire tread bulge out in a circumferentially annular manner, and at least one location between the center portion and a shoulder portion being annularly bulged in the circumferential direction. Included tires.