JPH03231003A - Pneumatic radial tire for bicycle - Google Patents

Abstract

PURPOSE:To increase a side force by embedding a reinforcing layer, formed of organic fiber cords, throughout the specified region of the side end part of a tread and setting a crossing angle of the organic fiber cord with a tire equator surface to a value within a specified range. CONSTITUTION:A tire comprises a carcass ply 2 formed of organic fiber cords extending in the direction of width, a belt layer 3 formed of peripherally extending organic fiber cords having a modulus of elasticity of 600kg/m<2> or more, and a tread part 4 with which a tread is formed. In this case, a reinforcing layer 5 formed of organic fiber cords is embedded in the side end part of a tread. The reinforcing layer 5 is disposed internally of a position outside the side edge of the belt layer 3 and in a range of from the side edge of the belt layer 3 to a position located approximate 1/4 of the belt layer. The crossing angle of the organic fiber cords, of which the reinforcing layer 5 is formed, with a tire equator surface X-X is set to a value within a range of 20-45 deg..

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention provides a motorcycle for use in motorcycles that provides excellent running stability and ride comfort, and that can ensure generation of side force of a sufficiently satisfactory magnitude. It relates to pneumatic radial tires.

(Prior Art) Conventional pneumatic tires for motorcycles include a carcass formed of one or more carcass plies made of organic fiber cords extending in the width direction of the tire, and cord elastic modulus extending in the tire circumferential direction. In addition to those comprising a belt formed of one or more belt layers made of organic fiber cord of 600 kg/mm2 or more, a carcass similar to that described above and an angle of 0° to 15° with respect to the tire equatorial plane. The belt includes a plurality of belt layers made of organic fiber cords extending in a direction in which the cords intersect with each other, and a reinforcing belt made of organic fiber cords that covers both end portions of the belt. Is there anything I can do?

Here, the former tire has excellent flexibility, so it is possible to increase the ground contact width to improve running stability, and it is also possible to improve the riding comfort by increasing the envelope characteristic. On the other hand, the latter tire can generate a large site force during cornering by providing high rigidity with a cross belt and a reinforcing belt.

(Problem to be solved by the invention) However, because of its flexibility, the former tire has a small camber thrust and cornering thrust that occur when turning, and especially when the tire has a large camber angle. When applied, this tendency is noticeable, and it cannot be denied that a feeling of stiffness occurs.

This is due to the fact that the rigidity of the tire ground contact area is lowered depending on whether the belt cord extends in the extending direction or the tire circumferential direction.

On the other hand, with the latter type of tire, the cross belt and reinforcing belt make the tire too hard, which makes the ride uncomfortable for the vehicle. When the vehicle is turning, the vehicle body reacts sensitively to irregularities in the tires or the tread, causing vibrations, or chattering, which greatly impairs driving stability.

The present invention advantageously solves the problems of the prior art, and provides a pneumatic radial tire for two-wheeled vehicles that provides excellent riding comfort and running stability to a vehicle, while also being able to generate a sufficiently large side force. It provides:

(Means for Solving the Problems) The present invention provides at least one carcass ply consisting of an organic fiber cord extending substantially in the tire width direction, and a cord elasticity modulus extending substantially in the tire circumferential direction. Or 600
A pneumatic radial tire for two-wheeled vehicles, comprising at least one belt layer made of organic fiber cords of kg/mm2 or more, and a tread portion forming a tread surface, the tread side end portions being made of organic fiber cords. One or two reinforcing layers are buried, and the area where this reinforcing layer is buried is
From a position outside in the tread width direction of the side edge of the belt layer buried over almost the entire tread width, inward in the tread width direction, approximately 1/4 from the belt layer side edge of the belt layer width along the belt layer surface. The intersection angle of the organic fiber cord forming the reinforcing layer with the tire equatorial plane is in the range of 20° to 45°.

(Function) In this tire, the belt layer made of organic fiber cords extending substantially in the circumferential direction of the tire can sufficiently reduce the rigidity of the belt layer against the force in the pushing direction of the tread surface. When applying a small camber angle, it is possible to improve the ride comfort of the vehicle due to the high envelope characteristics of the tire, and also ensure a wide ground contact width and provide excellent driving stability. .

On the other hand, when a large camber angle is imparted to the vehicle, the contact area at that time will be The rigidity can be increased appropriately, and therefore, it is possible to generate a sufficiently large side force and still effectively prevent the occurrence of chattering.

Note that the reinforcing layer is made of organic fiber cords because the same organic fibers are used for the carcass ply, which provides smooth cornering characteristics from straight-ahead driving to cornering (from a part of the tread center). This is to prevent sudden changes in the rigidity of the tread surface over a portion of the tread shoulder, and the reason why the number of reinforcing layers embedded is one or two is that without the reinforcing layer, a large camber angle would be created. It is not possible to increase the rigidity of the contact area as expected, and if there are more than three layers, the rigidity of the contact area becomes too high.
This is because charing similar to the conventional technology occurs.

In addition, the area where the reinforcing layer is buried in the tread side end portion is
From a position outside the side edge of the belt layer in the tread width direction,
Inward in the tread width direction, up to about 1/4 of the belt layer width along the belt layer surface from the belt layer side edge, if the reinforcing layer width in the tread width direction is made narrower than this. , the reinforcing layer cannot function effectively over the entire ground contact width when a camber angle is applied,
This will result in a lack of canker thrust, and if it is widened, stability during straight-ahead driving and performance on riding surfaces may be lacking. Here, the outer edge of the reinforcing layer in the tread width direction is located on the outer side than that of the belt layer, in order to make the camber thrust sufficiently large when the maximum camber angle is applied, and also, This is to eliminate inconveniences in terms of manufacturing, belt edge peeling, and other durability aspects, and the inner edge of the reinforcing layer in the tread width direction is separated from the edge of the belt layer side by about 1. 7
The reason why it is located at point 4 is due to the effect of the reinforcing layer, because during unnecessary straight running, if it is located on the inner edge of the reinforcing layer or the tread contact area, there is a risk of cord separation or other problems. This is because it is preferable that the inner edge of the reinforcing layer terminates at a position some distance away from the ground contact area during running.

Furthermore, if the intersection angle of the organic fiber cord forming the reinforcing layer with respect to the tire equatorial plane is in the range of 20° to 45°, it is difficult to expect an effective improvement in turning force if it is less than 20°. On the other hand, if the angle exceeds 45 degrees, the rigidity will become too high and the grip will be lost.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view in the width direction of a tire showing an embodiment of the present invention. In the figure, 1 indicates a ped core, and 2 indicates a carcass ply whose both ends are wrapped around a pair of bead cores 1. , 3 indicates one belt layer disposed on the outer peripheral side of the carcass ply 2, and 4 indicates a tread portion forming a tread surface.

Here, the carcass ply 2 is formed of an organic fiber cord extending in the tire width direction, in other words, extending in a direction intersecting the tire equatorial plane XX at an angle of 90°, and the tread portion 4 is Where the belt layer 3 reinforcing the entire area is formed of an organic fiber cord extending substantially in the tire circumferential direction and having a cord elastic modulus of 600 kg/mIn2 or more, at each tread side end portion,
A reinforcing layer 5 made of an organic fiber cord is embedded in the outer peripheral side of the belt layer 3.

Here, as is clear from the developed cross-sectional view shown in FIG. The reinforcing layer 5 is approximately 1/4 of the width of the belt layer along the surface of the belt layer from the edge of the belt layer side.
The intersection angle of the organic fiber cord forming the tire with the tire equatorial plane XX is, for example, 20°. The extending direction of the organic fiber cords forming the reinforcing layer at each side end portion should be symmetrical to each other with respect to the tire equatorial plane so as to provide the same turning characteristics when turning in either the left or right direction. It is preferable to do this, and it is particularly preferable that the cords at both end portions are arranged in a J-shape with respect to each other when viewed from the rear of the tire in the mounting position, as shown in FIG. According to this, it is possible to generate a larger grip force by applying a force in the direction indicated by the arrow in FIG. 3 to the reinforcing layer cord.

By the way, it is possible to bury not only one reinforcing layer 5 but also two reinforcing layers 5. In such a case, the cords of the two inner and outer reinforcing layers 5 can be extended in directions that intersect with each other. preferable.

Note that the reinforcing layer 5 can be buried in a state biased toward either the outer circumference side or the inner circumference side of the belt layer 3, regardless of whether it is one layer or two layers. In addition, especially when burying two reinforcing layers 5, each reinforcing layer 5 is
It can also be done with the belt layers separated,
For example, as shown in Fig. 4, when - reinforcing layers 5 are folded inside and outside the belt layer 3 and buried, - reinforcing layers 5 have the same function as burying two reinforcing layers. I can bring it.

According to the tire in which the reinforcing layer 5 is embedded in this manner, sufficient flexibility can be ensured in the area other than the area where the reinforcing layer 5 is embedded, resulting in excellent running stability and ride comfort. In addition, in the buried region of the reinforcing layer 5, it is possible to provide necessary and sufficient tread part rigidity to ensure generation of a sufficiently large side force,
Deterioration of running stability and riding comfort can be extremely effectively prevented.

Although this invention has been described above based on the illustrated example, it is also possible to make each of the carcass ply and the belt layer into a plurality of two or more layers.

[Comparative example]

A comparative test regarding camber thrust and envelope characteristics of the invention tire, conventional tire, and comparative tire will be described below.

Here, the size of the test tires is 170/60 R17, and the reinforcement structure of each tire is as shown in Table I.

For each of these tires, we conducted an indoor test on the tire itself, measured the camber thrust using a drum tester when a camber angle of 45° was given to the tire, and also measured the envelope characteristics on the drum tester. When evaluated by a protrusion riding test, the results shown in Table 2 as index values were obtained.

It should be noted that the larger the index value, the better the result.

Table 2 According to the second table, the invention tire 1. II is both
It is clear that it is possible to exhibit excellent envelope characteristics and also to ensure a sufficiently large camber thrust.

(Effect of the invention) Thus, according to the present invention, when the vehicle turns,
In particular, it is possible to generate a sufficiently large side force under the action of one or two reinforcing layers embedded in the tread side edge, and to prevent excessive increase in the tread side edge rigidity due to the reinforcing layer. In addition to the reinforcing layer itself, the carcass ply and belt layer effectively prevent this, thereby making it possible to realize excellent running stability and riding comfort of the vehicle.

[Brief explanation of drawings]

Fig. 1 is a sectional view in the tire width direction showing an embodiment of the present invention, Figs. 2 and 4 are developed cross-sectional views of the belt layer and the reinforcing layer, respectively, and Fig. 3 is the extending direction of the reinforcing layer cords. FIG. 1... Peedo core 2... Carcass ply 3
...Belt layer 4...Tread portion 5...
Reinforcement layer diagram above! ----Hee F top 2-hh Suarai 3- Bell F layer 4-1・-TO L7 TO'fP 5-・-M strong layer Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] 1. At least one carcass ply consisting of an organic fiber cord extending substantially in the width direction of the tire, and a cord having an elastic modulus of 600 kg/m extending substantially in the tire circumferential direction.
A pneumatic radial tire for two-wheeled vehicles, comprising at least one belt layer made of organic fiber cords of m^2 or more, and a tread portion forming a tread surface, the tread side end portions being made of organic fiber cords. One or two reinforcing layers are buried, and the buried region of the reinforcing layer is buried from a position outward in the tread width direction from the side edge of the belt layer buried over almost the entire tread width.
Inward in the tread width direction, up to about 1/4 of the belt layer width from the belt layer side edge along the belt layer surface, and the intersection angle of the organic fiber cord forming the reinforcing layer with the tire equatorial plane. A pneumatic radial tire for two-wheeled vehicles with an angle in the range of 20° to 45°.