JPS6368404A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce running distance at a high speed by providing at least one level difference in a peripheral direction and in a ring shape at both widthwise sides of a tire. CONSTITUTION:A level difference 5 is formed in a ring shape and in a peripheral direction on both widthwise sides of a tire tread 3. In forming said level difference 3, two radii of curvature RA and RB are made to cross each other and an intersection angle theta at the intersection point P2 thereof is st to about 5 deg.-15 deg.. According to the aforesaid constitution, running distance is reduced, operational stability is improved and it becomes easy to raise a running speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire that reduces running resistance during high-speed running.

[Prior art]

Conventionally, the part of the tread profile near the shoulder was made into a two-step profile (shoulder drop) using an inscribed circle to optimize the ground contact shape, but in this case, the contact area became too wide and running resistance increased. In particular, with competition tires, it is sometimes difficult to maintain a balance between running speed and handling stability.

[Purpose of the invention]

An object of the present invention is to provide a pneumatic tire that reduces running resistance during high-speed running and facilitates increasing running speed.

[Structure of the invention]

Therefore, the gist of the present invention is a pneumatic tire characterized in that at least one step is provided in a circumferential annular shape on at least both sides of the tire tread in the width direction.

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

FIG. 1 is a radial cross-sectional explanatory diagram of an example of a pneumatic tire of the present invention. In FIG. 1, a carcass layer 2 is installed between a pair of left and right bead parts 1, 1, and a belt layer 4 is arranged annularly in the tire circumferential direction on the carcass layer 2 in the tread part 3. There is. In addition, the tread portion 3
There is a step 5 on the surface of the tire, that is, on both sides in the width direction of the tire tread.
is provided in an annular shape in the circumferential direction of the tire. A plurality of steps 5 may be provided over the entire tire tread surface.

Note that 6 is a bead wire and 7 is a bead filler.

The tire shown in FIG. 1 has an aspect ratio of 60% or less.

FIG. 2 shows a tread profile of an example of a pneumatic tire of the present invention. In order to provide the zero step 5, the tread profile should have two or more radii of curvature, and as shown in FIG. What is necessary is to make the radius of curvature RA intersect with the radius of curvature RB on the outside.

It is preferable that the intersection angle θ at the intersection point P- between the radius of curvature RA and the radius of curvature RB is 5@~15°.If it is less than 5°, it is difficult to reduce the running resistance;
This is because if the angle exceeds 5°, the difference in height becomes too large and the steering stability deteriorates. A straight line may be formed between the intersection P2 and the ground end P1. A represents a tangent at the intersection Pg of the radius of curvature RA, and B represents a tangent at the intersection P3 of the radius of curvature RB.

Figure 3 (A) shows the contact surface of a tire with a conventional tread profile when it is stationary, Figure 3 (B) shows the contact surface of a tire with a conventional tread profile when it is under heavy load, and Figure 4 (A)
4(B) shows the contact surface of the tire with the tread profile of the present invention when the tire is at rest, and FIG. 4(B) shows the contact surface of the tire with the tread profile of the present invention when the tire is under heavy load. , b' are the area of the ground plane divided by i.

From these figures, ao and bo are almost equal, but a>b
It turns out that. That is, the tire of the present invention has a smaller contact patch area when stationary than the conventional tire, and therefore the tire of the present invention has lower running resistance than the conventional tire. Note that the tire with the tread profile of the present invention is the tire shown in FIGS. 1 and 2, and the tire with the conventional tread profile is a tire that does not have any step on the tread surface.

Next, from Table 1 below, which shows the results of comparing tire performance between the tire with the tread profile of the present invention and the tire with the conventional tread profile, it is clear that the tire of the present invention has superior tire performance. I understand.

Table 1 Notes: 1) In this case, the test is car; ABO3, tire size;
185/60 R14, air pressure; 2, 1kg/cn",
Course: I went to Kousei Sports Land.

2) In Table 1, the larger the index of feeling, the better.

3) Lap time is a comparison of best times.

〔Effect of the invention〕

As explained above, according to the present invention, since a step is provided on the tire tread, the ground contact pressure changes rapidly at the step, and when the load is low, the actual ground contact area becomes narrower and running resistance is reduced. Therefore, fuel consumption also decreases. In addition, when the load is high (braking, traction, cornering), the portion between the intersection point pg and the ground contact end P in FIG. 2 is also in contact with the ground to a certain extent, so that high grip can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a radial cross-sectional explanatory diagram of an example of a pneumatic tire of the present invention, FIG. 2 is an explanatory diagram showing a tread profile of an example of a pneumatic tire of the present invention, and FIGS. 3 (A) and (B)
4A and 4B are explanatory diagrams showing the contact surface of a tire with a conventional tread profile, and FIGS. 4(A) and 4(B) are explanatory diagrams showing the contact surface of a tire with a trend profile of the present invention. 1... Bead part, 2... Carcass layer, 3°... Tread part, 4... Belt layer, 5... Step.

Claims (1)

[Scope of Claims] A pneumatic tire characterized in that at least one step is provided in a circumferential annular shape on at least both sides of the tire tread in the width direction.