JPH02246809A - Pneumatic tire of excellence in braking performance - Google Patents

Abstract

PURPOSE:To improve braking performance on ice for a studless tire by making up a tread rubber with multi layers and forming in the land portion of each layer a number of cutouts in an alternate arrangement between adjacent layers. CONSTITUTION:A tread rubber (T) is formed in a multi-layer structure including three layers, T1 to T3. In positions corresponding to the land portion 2 of respective layers T1 to T3, a number of cutouts (C) with shallow depth are formed in an alternate arrangement to the adjacent layer. Such constitution permits high braking performance of a tire to be maintained without being degraded up to an end, and even if such a cutout as a sipe of being edge element is used a lot, the rigidity of the land portion 2 of a tread is not adversely affected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) Tires used for running on snowy and/or icy roads, such as studless tires, are required to have high traction and braking performance.

This invention aims to advantageously improve the driving performance on snow and ice, especially the braking performance on ice, of pneumatic tires installed on vehicles that drive on such snowy and icy roads.

(Prior Art) As a means of improving the performance of tires used for driving on snowy and/or icy roads, land areas (blocks) forming part of the tire tread pattern are used to increase the edge component of the tire. It has been well known that it is effective to provide a large number of sipes (corresponding to blocks in the pattern).

By the way, when a large number of sipes are provided on the land portion of the tread surface of a tire, the rigidity of the land portion is reduced, which not only has a negative effect on traction on snow-covered roads, but also increases the bending deformation of the blocks, causing the tread surface to deteriorate. Due to the small contact area of the tread and the local pressure increase on the tread surface, a large amount of melted water will be generated between the tire and the road surface, so avoid deterioration of braking performance, especially on icy roads. It's tough.

For example, if the cutting depth of the sipe is made as small as possible, it is possible to avoid a decrease in rigidity in the land area even if it is used frequently, but shallow sipes will quickly lose their function due to tread wear.

(Problem to be solved by the invention) It is possible to increase the edge component of a tire without adversely affecting the rigidity of the land portion on the tread surface, thereby improving braking performance, especially on road surfaces such as ice, where the formation of a water film is unavoidable. It is an object of the invention to propose a pneumatic tire which can be advantageously improved and improved.

(Means for Solving the Problems) The present invention provides a pneumatic tire having a tread rubber in which grooves and land portions separated by the grooves are arranged on the entire surface of the tread to form an uneven tread pattern. , the above-mentioned tread rubber is a pneumatic tire with excellent braking performance, characterized in that the tread rubber has a multi-layer laminated structure, and each layer of the tread rubber has a large number of notches arranged in a manner that is difficult to differentiate from the adjacent layer. Here, the above-mentioned uneven pattern is preferably arranged in a block arrangement for driving on snowy/icy roads, and the blocks have connecting portions between them to form a platform that connects the blocks along the periphery of the tread. .

Now, FIG. 1 shows the main parts of the tread part of the pneumatic tire according to the present invention, and FIG. 2 shows an enlarged cross section of the AA in FIG. 2 is a land portion separated by the groove l, 3 is a block, for example, which divides the land portion 2 by the groove l, and 4 is a connecting portion that connects the blocks 3 around the tread to form a platform. The groove portions 1 and the land portions 2 form an uneven tread pattern on the entire surface of the tread.

The tread rubber T has a multilayer laminated structure (in this example, T3, T
It is shown as three layers, T2 and T3. ), and each of these layers has a large number of cuts C at positions corresponding to the land portions 1, which are arranged in a manner that is slightly different from each other with respect to the adjacent layer, and each of which has a shallow cutting depth.

In this example, for convenience of the manufacturing process, the second layer Tt and the third layer T are constructed as an integral structure, and shallow cuts C are alternately formed on both the front and back sides of the structure in a slightly different arrangement. The second layer and the second layer may be separately formed and laminated with the eye on the imaginary line rr as the boundary.

Note that the internal structure of the tire is the same as that of a general radial tire, and is not illustrated here.

(Function) In this invention, the tread rubber T has a multi-layered laminated structure, and each layer is provided with a large number of cuts C that are arranged in a way that is hardly mutually different from the adjacent layer. Even if cuts such as sipes are used frequently, the rigidity of the land portion 2 in the tread portion will not be adversely affected, and even if the tire tread gradually wears out as the tire runs, the cuts C pre-formed in each adjacent layer can be used. , appear one after another, so there is no risk that the braking performance of the tire will deteriorate until the end of the run.

In addition, in the case shown in FIG. 2, when the second layer and the third layer have an integral structure, the cut C on the adjacent surface may have a structure as shown in FIG. 3. In this case, there is an advantage that there is little variation in running performance because the 2nd Nth notch appears before the third layer wears out and the notch there disappears.

Pneumatic tires with such a laminated tread structure,
For example, the recap of a retreaded tire can be easily produced by sequentially laminating multiple layers of tread rubber, especially when precure tread rubber is used.Of course, this invention can be applied to retreaded tires. Needless to say.

Although the above explanation specifically deals with the case where blocks are arranged in the tread of a tire, the present invention is not limited to block arrays; ribs, lugs, etc. can be used depending on the nature of the road surface. It can also be applied to tread patterns such as ribs and lugs.

(Example) A tire of 10.0OR20 (filled with regular internal pressure) having blocks as shown in FIG. 4(a) in the tread part,
20 km/h using a 2-D vehicle (2-axle diameter wheel drive, truck with a regular load capacity of 8 tons) equipped with both front and rear wheels.
Driving tests were repeatedly conducted in which sudden braking was applied at h, and the braking performance of the tire on an icy road surface (ice temperature -5° C.) was investigated.

In this test, a tire having the same size and having the blocks shown in FIG. 4(b) was used as a reference.

The results are shown in the table below, and the tire used as a comparison tire with blocks as shown in Figure 4 (C) (simply increasing the number of notches) had low rigidity, and was 40% stiffer.
It has been confirmed that the tire according to the present invention exhibits stable performance over a long period of time, whereas when worn, the tire cannot exhibit sufficient performance due to the occurrence of uneven wear.

Braking Distance Index on Ice (High → Good) (Effects of the Invention) According to the present invention, the running performance of the tire on snowy and icy road surfaces is improved by increasing the edge component in the land area of the tread surface without reducing its rigidity. In particular, braking performance is improved and stable driving can be realized.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of the main parts of a pneumatic tire according to the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, and FIG. Figures 4(a), 4(b), and 4(c) are sectional views of main parts of the pneumatic tire used in the example. 0...Groove portion 3...Block C...Notch T...Tread rubber T1...First layer T2...Second layer T,...Third layer 2...Land portion 4 ...Connection part

Claims (1)

[Claims] 1. A pneumatic tire having a tread rubber in which grooves and land portions separated by the grooves are arranged on the entire surface of the tread to form an uneven tread pattern, wherein the tread rubber is A pneumatic tire with excellent braking performance, characterized in that it has a multi-layered laminated structure, and each layer of tread rubber has a large number of notches arranged in a manner that is difficult to differentiate from the adjacent layer. 2. The pneumatic tire according to claim 1, wherein the uneven pattern is arranged in blocks, and the blocks have connecting portions between the blocks to form a platform for connecting the blocks along the periphery of the tread.