JPS63287606A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve traveling stability on all road surfaces, in a pneumatic tire having lugs in the side areas of portion by forming round shoulders and square shoulders on the lugs. CONSTITUTION:On the side areas of a tread portion 1, there are formed lugs 3 having round shoulders 4 and lugs 3 having square shoulders 5, by means of cuttings 2. In the case, each round shoulder 4 is projected outward from each square shoulder 5, and further, the ratio W2/W1 is set to about 0.8-0.98, wherein W1 represents the tread width in the round shoulder 4 and W2 represents that in the square shoulder 5. With this constitution, stable traveling can be obtained on all road surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to an improvement in the shoulder shape of a pneumatic tire having a plurality of lugs defined by cuts in the tread side region.

At the side edge of the tread portion of the tire, either a so-called round shoulder having an arc shape or a so-called square shoulder having a substantially corner shape is arranged depending on the use of the tire.

(Prior Art) Even in pneumatic tires having a plurality of lugs on the sides of the tread portion of the tire, round shoulders or square shoulders are applied to the side edges of the lugs depending on the purpose.

As is generally known, tires with round shoulders on the lugs are suitable for use mainly on ordinary roads and can ensure smooth handling stability, but they tend to catch on the road surface on snowy roads, muddy roads, etc. However, because the grip force in the direction transverse to the direction of travel of the car is insufficient, problems remain with straight-line performance and cornering characteristics.

On the other hand, tires with square shoulders on the lugs have strong grip across the direction of travel of the vehicle and have excellent straight-line performance and cornering characteristics, making them suitable for use on snowy and muddy roads, but especially on rutted roads. - There was a problem that the lugs were likely to get caught in the ruts when traveling on a ship's route, and the reaction force at that time caused the steering wheel to become loose, impairing the ability to go straight. (Problem that the invention aims to solve) It is an object of the invention to advantageously solve the above-mentioned problems in tires with multiple lugs in the side region of the tire and to achieve stable running on all road surfaces.

(Means for Solving the Problems) The present invention provides a pneumatic tire having a plurality of lugs, in which at least a side region of the tread of the tire is divided by a plurality of cuts at substantially equal intervals on the tread circumference. The lug is a pneumatic tire with round shoulders and square shoulders.

In this pneumatic tire, it is recommended that the round shoulders on the lugs be provided so as to protrude from the square shoulders, and that the round shoulders and square shoulders be arranged alternately on the circumference of the tread. .

Also, the length of the lug along the tread circumference is 3 of the tread width.
It is preferable to set it in the range of ~50%.

Now, FIG. 1 illustrates the tread side area of a pneumatic tire according to the present invention.

In the figure, 1 is the tread portion of the tire, 2 is notches extending in the tread width direction formed at substantially equal intervals on the circumference on both sides of the tread portion l, and 3 is a lug divided on the tread circumference by the notches 2. The lug 3 has a round shoulder 4 and a square shoulder 5.

Here, the round shoulders 4 are provided on the lugs 3 so as to protrude outward from the square shoulders 5, and the tread width W at the round shoulders 4 is as shown in FIG.
It is advantageous to set the ratio W z /W + of I to the tread width W at the square shoulder 5 to be in a range of 0.8 to 0.98.

The curvature of the side edge of the tread, that is, the curvature of each shoulder, is as shown in Fig. 2. The radius of curvature R for the round shoulder is 5≦R≦50 (mm), and the radius of curvature r for the square shoulder is 0≦. r≦5 (+++
+s) is preferable.

(Function) On ordinary roads, the round shoulders ensure smooth steering stability, ensuring stable straight-line performance without the steering wheel becoming loose due to ruts, and on snowy or muddy roads. The function of the shoulder ensures grip across the direction of travel of the car,
Therefore, it is possible to obtain stable straight-line performance and cornering performance, and it can demonstrate excellent performance on any road surface.

By placing the round shoulder on the outside of the square shoulder, it is possible to secure straight-line stability, which is an advantage of the round shoulder, but this means that contact with the ruts always occurs on a part of the outside round shoulder. This is why the handle does not get caught and the handle cannot be removed.

(Example) Tire size 31xl with multiple lugs shown in Figure 3
A test tire of O.50R15LT was manufactured as a prototype, but the main constituent parts of the tire other than the tread side parts were omitted from illustration because they conformed to the customary practice for conventional tires.

In the above tire size, the tread width W1 of the lugs 3 with round shoulders 4 is 206 mm, the tread width Wz of the lugs 3 with square shoulders 5 is 195 M, and the radius of curvature R of the round shoulders 4
is 15 mm, and the radius of curvature r of square shoulder 5 is 2 m.
The length of the lug along the tread circumference was set to 27 mm, and the cutting width l was set to 311 mm.

For comparison, a rug with only round shoulders (
The same size was applied to the conventional tire A) and the lug with only square shoulders (conventional tire B).

The results of a comparative test of steering stability performance on ordinary roads, performance on snow, performance on muddy soil, and performance on ruts are as follows.

Note) The performance of conventional tire A is expressed as an index with the performance as 100, and the larger the index, the better.

The steering stability performance test on the ship route was evaluated by a sensitivity test using an actual vehicle.

The on-snow performance test was evaluated using a sensitivity test using an actual vehicle.

The mud performance test was evaluated using a sensitivity test using an actual vehicle.

Also, the rut riding performance, so-called wandering performance test, was evaluated by a sensitivity test using an actual vehicle.

(Effects of the Invention) The pneumatic tire of the present invention has both the advantages of round shoulders and square shoulders, and thus can provide a pneumatic tire that can be used in a wide range of applications regardless of road surface conditions.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a tread side area of a pneumatic tire according to the invention, FIG. 2 is an explanatory view showing each shoulder, and FIG. 3 is an explanatory view showing a specific example of the invention. ■...Tread part 2...Notch 3...Lug 4...Round shoulder 5...
Square Shoulder Patent Applicant: Brideston Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A pneumatic tire comprising a plurality of lugs, each of which has at least a side region of its tread divided by a plurality of cuts at substantially equal intervals on the circumference of the tread, wherein the lugs have round shoulders. A pneumatic tire with square shoulders.