JP2007290533A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle excellent in sustainability of high grip performance when cornering at high speed by eliminating the problem of a deterioration in physical property of a tread rubber in applying a spiral belt circumferentially. <P>SOLUTION: The pneumatic tire for the motorcycle has: carcasses 2 respectively turned and locked around bead cores 1 respectively embedded in a pair of bead parts 11 as a skeleton, and is provided with a tread part 12 arranged on the outer periphery of a crown part of the carcasses 2; a pair of sidewall parts 13 extending inward from both ends of the tread part in a tire radial direction; and the spiral belt 3 composed of a rubber-coated cord spirally coiled circumferentially, arranged radially outside of the carcass on the tread part in the tire. A rubber layer 4 having JIS hardness of 40 to 60 extending circumferentially is arranged in an end portion area of the tread part covering at least both the end parts of the spiral belt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for motorcycles (hereinafter, also simply referred to as “tire”), and more specifically, for motorcycles that are excellent in sustainability of high grip performance during high-speed running and that are particularly suitable for road racing applications. Related to pneumatic tires.

  In recent years, the speed of motorcycles has been increased more and more, and accordingly, even in pneumatic tires for motorcycles, a circumferential spiral belt is provided on the outermost belt layer so that it can withstand circumferential force due to centrifugal force during high-speed running. The structure which arranged is common.

  In particular, the performance of motorcycles for road racing has improved recently, and in addition to higher speeds, higher torque has been achieved, and it has become possible to improve cornering performance at high speeds in addition to grip performance at high speeds. Occupies a significant weight, and it is required that these high-speed performances can be maintained until the end of the race.

As an improved technology related to a pneumatic tire for a motorcycle, for example, Patent Document 1 has a tread portion, a sidewall portion, and a bead portion for the purpose of realizing a motorcycle tire excellent in durability at high speed running. And a toroidal carcass whose ends are folded around the bead core, a breaker composed of 2 to 3 plies arranged radially outwardly, and arranged between the breaker plies at both ends of the breaker, and an upper ply end. A technique is disclosed in which a cushion rubber having a JIS hardness of 40 ° to 75 ° disposed in the vicinity and a band layer disposed in the center of the tread outside the breaker are provided. Further, in Patent Document 2, in an aircraft tire, a cushion rubber that gradually decreases in thickness is arranged at both ends of the belt layer between the lower end of the belt layer and the carcass at both ends of the belt layer. It is disclosed that stress concentration can be effectively absorbed and relaxed.
Japanese Patent Laid-Open No. 61-16105 (Claims, [FIG. 1], etc.) JP-A-61-57407 (page 4, upper left row, lines 16 to 20)

  However, in the tire having the structure using the circumferential spiral belt as described above, since the amount of deformation absorption with respect to the in-plane shear deformation of the spiral belt is small, a large shear deformation is repeatedly input to the tread rubber and the physical properties of the tread rubber. There was a problem that the deterioration was promoted and the gripping power at the time of cornering was lowered.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic tire for a motorcycle that solves the above-described problems when applying a circumferential spiral belt and is excellent in sustainability of high grip performance when cornering at high speed.

  As a result of diligent study, the present inventor has arranged a rubber layer having a predetermined hardness extending in the circumferential direction at the end of the circumferential spiral ebelt, and this rubber layer causes a shear input to the tread rubber during high-speed cornering. Discovered that it can absorb deformation, reduce deformation load of tread rubber, prevent deterioration of its physical properties, and as a result it can maintain high grip performance during cornering, and completes the present invention It came to do.

That is, the pneumatic tire for a motorcycle according to the present invention has a carcass folded and locked around a bead core embedded in each of a pair of bead portions, and a tread portion disposed on the outer periphery of the crown portion of the carcass. And a pair of sidewall portions extending inward in the tire radial direction from both ends of the tread portion, and a rubber-coated cord spirally wound in the circumferential direction on the outer side in the tire radial direction of the carcass in the tread portion In a pneumatic tire for a motorcycle in which a spiral belt made of
A rubber layer having a JIS hardness of 40 to 60 extending in the circumferential direction is disposed at least at both ends of the tread portion covering the end portion of the spiral belt.

  In the present invention, it is preferable that the gauge of the rubber layer gradually increases from the tire center side toward the spiral belt end portion side and is equal to or less than ½ of the total rubber gauge at the spiral belt end portion.

  Furthermore, it is preferable that the arrangement | positioning area | region of the tire width direction of the said rubber layer occupies 1/3 or more from a tread part edge part side among tire center-tread part edge parts. The tire of the present invention is particularly suitably used for the rear.

  According to the present invention, the above configuration eliminates the problem of deterioration of physical properties of the tread rubber when the circumferential spiral belt is applied, and is used for a motorcycle excellent in sustainability of high grip performance when cornering at high speed. It became possible to realize a pneumatic tire.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 shows a cross-sectional view of an example of a pneumatic tire for a motorcycle according to the present invention. As shown in the figure, a pneumatic tire 10 for a motorcycle according to the present invention has a carcass 2 folded and locked around a bead core 1 embedded in a pair of bead portions 11, and a crown portion of the carcass 2. A tread portion 12 disposed on the outer periphery and a pair of sidewall portions 13 extending inward in the tire radial direction from both ends thereof are provided, and the outer side of the carcass 2 in the tire radial direction of the tread portion 12 spirals in the circumferential direction. A spiral belt 3 made of a rubber-coated cord wound in a shape is disposed.

  In the present invention, as shown in the drawing, it is important that rubber layers 4 having a JIS hardness of 40 to 60 extending in the circumferential direction are disposed at both ends of the tread portion covering at least the end portion of the spiral belt 3. is there. By disposing the rubber layer 4 having a hardness higher than that of the tread rubber at the end of the spiral belt 3, it is possible to increase the rigidity at the end of the belt and exert a wear mitigating effect. By absorbing and reducing the input shear deformation and preventing the deterioration of its physical properties, the grip performance during cornering can be satisfactorily maintained without deteriorating.

  The rubber layer 4 needs to have a JIS hardness of 40 to 60. By setting the JIS hardness within this range, the desired effect of the present invention can be obtained. As long as the rubber layer 4 satisfies the above hardness, the composition of the rubber to be used is not particularly limited.

  Further, the rubber layer 4 is required to be disposed in a region covering at least both ends of the spiral belt 3, but as shown in the figure, between the tire center and the tread portion end portion on one side in the tire width direction. It is preferable to occupy 1/3 or more from the end of the tread portion. By disposing the rubber layer 4 so as to occupy 1/3 or more from the end side of the tread portion, it is more effective in preventing performance deterioration at a high camber angle (CA) (40 degrees or more).

  Further, as shown in the figure, the gauge of the rubber layer 4 gradually increases from the tire center side toward the spiral belt end side, and has a thickness of 1/2 or less of the total rubber gauge at the spiral belt end part. Is preferred. If the thickness of the rubber layer 4 exceeds 1/2 of the total rubber gauge of the tread portion, the rigidity may be lowered and the grip (= cornering) performance may be lowered.

  In the tire 10 of the present invention, details of the tire structure and materials other than the provision of the rubber layer 4 are not particularly limited, and can be appropriately determined according to a conventional method. For example, the carcass 2 that forms the skeleton of a tire is formed by rubber coating with organic fiber cords such as nylon and polyester juxtaposed in parallel. In the example shown in the figure, the carcass 2 is provided with one or more layers. There is no particular limitation.

  The spiral belt 3 is formed by spirally winding a long rubber-coated cord in which one cord is covered with rubber or a belt-like ply in which a plurality of cords are covered with rubber, and the cord direction is substantially In addition to the steel cord, the cord includes an aromatic polyamide aramid (for example, product name: Kevlar manufactured by DuPont), polyethylene naphthalate (PEN), polyethylene terephthalate (PET). ), Rayon, xylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), aliphatic polyamide such as nylon, and glass fiber or carbon fiber. Can be used. In the present invention, the spiral belt 3 is provided as the outermost layer belt. However, if desired, one or more belt layers can be further provided on the inner side in the tire radial direction of the spiral belt 3.

  Further, although not shown, a tread pattern is appropriately formed on the tread portion 12 of the tire 10, and an inner liner is formed on the innermost layer of the tire 10.

  Since the pneumatic tire 10 for a motorcycle of the present invention has the above-described configuration, it can be suitably used particularly for the rear, and is preferably used for road racing motorcycles.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Example)
A pneumatic tire for a motorcycle of an example having the cross-sectional structure shown in FIG. 1 was manufactured at tire sizes 190 / 650R16.5 (rear) and 125 / 600R16.5 (front). A rubber layer 4 satisfying a JIS hardness of 40 to 60 extending in the circumferential direction was disposed in both end regions of the tread portion covering the end portion of the spiral belt 3. The gauge of the rubber layer 4 was assumed to gradually increase from the tire center side toward the spiral belt end side as shown in the figure.

(Conventional example)
A conventional pneumatic tire for a motorcycle was manufactured with the same structure as the example except that the rubber layer 4 was not provided.

The test tires of the example and the conventional example were applied to a commercially available motorcycle, and the rider evaluated the feeling of high-speed straight running stability, traction performance, full bank grip performance, and grip durability. A result is shown by the score of 1-5, and it is so favorable that a numerical value is large. Further, regarding the grip durability, the lap time difference was also evaluated, and indicated by an index with the conventional example as 100. The smaller the value, the lower the rate of decrease and the better.
These results are shown in Table 1 below.

  As shown in Table 1 above, in the tire of the example in which the predetermined rubber layer 4 is provided, the grip durability is maintained in both the feeling evaluation and the lap time evaluation as compared with the conventional tire in which the rubber layer 4 is not provided. In addition, it was confirmed that the evaluation items of high-speed straight running stability, traction performance, and full bank grip performance were equivalent to those of the conventional example.

1 is a cross-sectional view showing a motorcycle pneumatic tire according to a preferred embodiment of the present invention.

Explanation of symbols

1 Bead core 2 Carcass 3 Spiral belt 4 Rubber layer 11 Bead portion 12 Tread portion 13 Side wall portion

Claims (4)

A carcass folded and locked around a bead core embedded in each of the pair of bead portions, and a tread portion disposed on the outer periphery of the crown portion of the carcass, and inward in the tire radial direction from both ends of the tread portion And a pair of sidewall portions extending in the tire, and a spiral belt made of a rubber-coated cord spirally wound in the circumferential direction is disposed outside the carcass in the tire radial direction at the tread portion. In the tire,
A pneumatic tire for a motorcycle, wherein a rubber layer having a JIS hardness of 40 to 60 extending in the circumferential direction is disposed at least in a tread portion end region covering both ends of the spiral belt.   The pneumatic tire for a motorcycle according to claim 1, wherein the gauge of the rubber layer gradually increases from the tire center side toward the end of the spiral belt and is equal to or less than ½ of the total rubber gauge at the end of the spiral belt. tire.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein a region in which the rubber layer is disposed in a tire width direction occupies 1/3 or more from a tread portion end portion side between a tire center and a tread portion end portion.   The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the tire is used for a rear.

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