JPH04342603A - Tire for motorcycle - Google Patents

Abstract

PURPOSE:To improve the straight advance stability, turning performance, and drive feeling in the high speed traveling, with good balance. CONSTITUTION:A carcass 6 having the carcass cords which are tilted in an angle of 70-90 deg. with respect to a tire equator C and a belt layer 7 consisting of at least a ply piece 7a which is formed by winding a long small width strip shaped ply in which at least one belt cord is embedded into a topping rubber, in tilt form by a small angle with respect to the tire equator C are provided, and the 100% modulus of the rubber of a side wall part 3 is made smaller than that of the rubber of a tread part 2, and the longitudinal spring constant is set to 14.0-17.0kgf/mm.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention improves straight-line performance during high-speed driving and stability during turning, and
This invention relates to motorcycle tires that can improve riding comfort.

0002

[Prior Art] Conventionally, motorcycle tires for on-road driving have been manufactured primarily to prevent tire damage and maintain durability for high-speed driving on expressways, etc. . As a result, running stability, turning performance, and ride comfort during high-speed running were not necessarily satisfactory.

0003

[Problems to be Solved by the Invention] However, in recent years, the number of long-distance drives on expressways by motorcycles has increased, and there is a growing demand for further improvement in tire performance in straight running stability and riding comfort.

On the other hand, the tight turning radius of motorcycles has been reconsidered, and improvements in their turning performance are also required. Unlike four-wheeled vehicles, motorcycles perform turns unique to two-wheeled vehicles, in which the vehicle turns by tilting its body. As a result, when turning, the tire's contact patch moves from the center area of the tread near the tire equator toward the tread edge, and the ground contact and grip feel is different from when driving straight, making rapid turns possible. The problem is that there is no.

The inventors have found that in order to improve straight-line performance during high-speed running, stability during turning, and ride comfort, the carcass and belt layers are arranged in a radial manner, and the rubber of the sidewall portion is By making the 100% modulus smaller than that of the rubber in the tread, and by regulating the longitudinal spring constant of the tire itself to a lower and fixed range than conventional tires, we believe that these performances can be improved in a well-balanced manner. Heading: The present invention has been completed.

An object of the present invention is to provide a tire for a motorcycle that can improve high-speed performance during high-speed running, turning performance, and riding comfort in a well-balanced manner.

[0007]

[Means for Solving the Problems] The present invention provides at least one carcass cord having a carcass cord that extends from the tread portion, passes through the sidewall portion, wraps around the bead core of the bead portion, and is inclined at an angle of 70 to 90 degrees with respect to the tire equator. A carcass consisting of one carcass ply, and a long narrow band ply arranged inside the tread part and outside the carcass in the tire radial direction and having one or more belt cords embedded in the top pig rubber. a belt layer consisting of at least one piece of ply wound at an angle, and the 100% modulus of the rubber in the sidewall portion is smaller than the 100% modulus of the rubber in the tread portion; When the tire is attached to the rim and the specified internal pressure and load are applied to the tire, the longitudinal spring constant is 1.
This is a motorcycle tire having a tire pressure of 4.0 kgf/mm or more and 17.0 kgf/mm or less.

[0008] Here, the longitudinal spring constant refers to the condition when the rim is attached and a specified internal pressure is applied to the tire bore.
By applying a vertical load to the tire and causing the tire to deflect, the load-deflection correlation is determined and expressed as the slope of the tangent at the actual operating load in the deflection curve. Note that the actual operating load is the actual vehicle load, which is the actual vehicle load obtained by adding the rider's weight to the maintenance weight of the motorcycle, and is distributed to each wheel according to the sharing ratio of the front wheels and rear wheels.

[0009]

[Function] The carcass has a radial arrangement in which the inclination of the carcass cords is 70 to 90 degrees with respect to the tire equator, and the belt cords of the belt layer are inclined at a small angle with respect to the tire equator. The carcass cord and the belt cord intersect at a large intersecting angle, increasing the rigidity of the tread portion. With such a configuration, running performance when traveling straight can be maintained.

[0010] Furthermore, since the belt layer is formed of ply pieces wound around a long belt-shaped ply, the belt layer does not have seams in the tire circumferential direction like the belt layer formed by splicing together conventional sheet plies. This makes it possible to further enhance straight-line driving performance and improve riding comfort.

[0011] Further, the regulation of the longitudinal spring constant is determined by the tire configuration, such as the modulus of the rubber in the tread and sidewall parts, the thickness of the rubber, the composition of the carcass and belt layers, and the composition of the bead apex. Many elements are related, and as an example of each configuration,

This is shown in Examples 1 to 4 of Table 1 in the [Specific Examples] section.

If the longitudinal spring constant is less than 14 kgf/mm, the straight-line stability and turning performance during high-speed running will be poor, and if the longitudinal spring constant is more than 17 kgf/mm, the riding comfort will be reduced.

[0013] In conventional motorcycle tires, the longitudinal spring constant is set to 20 kgf/mm or more, and the rubber in the tread and the rubber in the sidewall are of the same type and have the same performance. However, if the 100 modulus of the sidewall portion is lower than that of the rubber of the tread portion as in the present invention, ride comfort can be improved without reducing straight-line stability and turning performance. .

[0014] Thus, in the present invention, by organically combining and integrating the above structures, it is possible to improve straight-line stability, turning performance, and riding comfort during high-speed running in a well-balanced manner.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 to 5, a radial tire 1 for a motorcycle includes a tread portion 2, a sidewall portion 3 extending from both ends of the tread portion 3 inward in the tire radial direction, and a bead located at the inner end of the sidewall portion 3 in the tire radial direction. part 4, passing from the tread part 2 through the sidewall part 3,
A carcass 6 is provided with a winding part 6b for winding up the bead core 5 from the inner side in the tire axial direction to the outer side in the main body part 6a extending in the bead part 4, and the carcass 6 is arranged inside the tread part 2 and on the outer side in the radial direction of the carcass 6. A belt layer 7 is provided. Further, a bead apex 9 having a triangular cross section is raised on the outer side of the bead core 5 in the tire radial direction and between the winding portion 6b and the main body portion 6a.

The carcass 5 is made of one or more carcass plies, in this embodiment one carcass ply, in which the carcass cord is inclined at an angle of 70 to 90 degrees with respect to the tire equator C, and the carcass cord is made of nylon, rayon, A cord made of organic fiber such as polyester or aromatic polyamide and having an elastic modulus of 30 to 65 g/d is used.

In this example, the carcass ply and the carcass cord have a 100% modulus of 18 to 25 kg/
The dots are formed on a cm2 top pig with a number of dots in the range of 35 to 45 per 5 cm.

In this embodiment, the winding portion 6b has a winding height Hc from the bead bottom surface 15 equal to the tread edge height H from the bead bottom surface 15 of the edges E1 and E2 of the tread portion 2.
It is set in a range of 0.18 to 0.45 times s to give flexibility to the sidewall portion and reduce the longitudinal spring constant.

The belt layer 7 is composed of one or more ply pieces 7a in this embodiment, and the ply piece 7a is formed by winding a long belt-shaped ply 10 around the outside of the carcass 6. .

As shown in FIG. 2, the belt-shaped ply 10 is made up of one belt cord 11 or a plurality of belt cords 11 arranged in parallel, two belt cords 11 in this embodiment, embedded in top pig rubber 12, and the belt cord 11 is made of nylon or aromatic rubber. Polyamide, polyester, etc. having an elastic modulus of 200 to 350 g/d are used.

In this embodiment, the topping rubber 1
2 has its 100% modulus of 25 to 40 kg/cm
It is set in the range of 2.

When the ply piece 7a is molded,
As shown in FIG. 3, adjacent side edges 10a of the strip ply 10
, 10a are wrapped around each other and inclined at a small angle close to 0° with respect to the tire equator C, and the tread portion 2 is wound spirally from one side edge E1 to the other side edge E2. The belt-shaped ply 10 is prevented from loosening. When winding the belt-shaped ply 10, it is preferable to wind the belt cords at a pitch corresponding to a number of belt cords of 30 to 40 cords/5 cm.

In this embodiment, the bead apex 9 has the following characteristics:
A rubber having a rubber hardness of JISA hardness of 60 degrees or more is used, and the tip height Hb from the bead bottom surface 15 is the tread edge height, which is the height of the end edges E1 and E2 of the tread portion 2 from the bead bottom surface 15. It is set to be 0.15 times or more and 0.40 times or less of Hs.

Furthermore, in this embodiment, the composition of the rubber disposed on the outside of the carcass 6 or the belt layer 7 is different between the tread portion 2 and the sidewall portion 3. The rubber 13 of the tread portion 2 has a 100% modulus of 18
While the modulus is set to a normal value of ~25 kg/cm2, the rubber of the sidewall portion 3 has a modulus of 1
The 100% modulus is 10 to 16 kg/cm2, that is, the 100% modulus is lower than that of the rubber of the bead portion 2.

Furthermore, in this embodiment, the average value of the cross-sectional thickness Ts in the axial direction of the tire located radially inward from the carcass maximum width WK position in the sidewall portion 3 is in the range of 3 to 5 mm, It is slightly smaller than the rubber thickness of the wall part.

The carcass 6 and the belt layer 7 may be formed by overlapping two or more carcass plies or belt pieces.

The present invention comprises the carcass 6, the belt layer 7, and the bead apex 9 having the above-described structure, and the tread portion 2 and the sidewall portion 3 have the above-mentioned 100%
By using rubber with a high modulus and rubber thickness, the longitudinal spring constant of the tire can be increased from 14.0 kgf/mm to 17.0 kg without having to form the tire into a unique cross-sectional configuration.
gf/mm range, and it is possible to improve straight running performance and turning performance at high speeds, as well as ride comfort.

[0028]

[Specific Example] A tire with a tire size of 170/60VR and a configuration shown in Figure 1 was prototyped (Examples 1 to 4) with the specifications shown in Table 1, and a test was conducted to confirm its performance. . Note that tires with conventional configurations (Comparative Examples 1 and 2) and tires other than the configuration of the present application (Comparative Example 3)
-10) were also prototyped and their performances were compared. Note that the longitudinal spring constant is expressed as a measured value in the range of (150±25) kg.

In the test, a sample tire was mounted on the rear wheel of a 750 cc class motorcycle, and the tire was run on a test road, and the results were judged based on the driver's feeling, and the result was expressed as an index, with Comparative Example 1 being 100. The larger the value, the better.

The test results are shown in Table 1.

[0031]

[Table 1]

As a result of the test, it was confirmed that the high-speed straight running stability, turning performance, and ride comfort of the example were improved in a well-balanced manner compared to the comparative example.

[0033]

As described above, the motorcycle tire of the present invention includes a radially arranged carcass and a belt layer made of ply pieces formed by winding belt-shaped ply, and also has a longitudinal spring of the tire. Since the constant is lower than that of conventional models and within a certain range, it improves straight running performance, turning performance, and riding comfort at high speeds in a well-balanced manner, making it possible to respond to the increasing speeds of motorcycles.

[0034]

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the belt-like ply.

FIG. 3 is a cross-sectional view illustrating the winding of a band-shaped ply.

FIG. 4 is a developed plan view showing a carcass and a belt layer.

[Explanation of symbols]

2 Tread part 3 Sidewall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 7a　Ply piece 10 Band ply 11 Belt cord 12 Topping rubber 13, 14 Rubber C Tire equator

Claims (1)

[Claims] [Claim 1] A carcass consisting of at least one carcass ply having a carcass cord that extends from the tread part, passes through the sidewall part, wraps around the bead core of the bead part, and is inclined at an angle of 70 to 90 degrees with respect to the tire equator. and at least a long and narrow band-shaped ply arranged inside the tread part and outside the carcass in the tire radial direction and having one or more belt cords embedded in the toppig rubber and wound at a small angle with respect to the tire equator. a belt layer consisting of one ply piece, and the 100% modulus of the rubber in the sidewall portion is smaller than the 100% modulus of the rubber in the tread portion, while the bead portion is attached to the rim and the tire A motorcycle tire having a longitudinal spring constant of 14.0 kgf/mm or more and 17.0 kgf/mm or less when a specified internal pressure and load are applied to the tire.