JPH0456604A - Radial tire for motorbicycle - Google Patents

Abstract

PURPOSE:To balance linear forward properties with cornering running properties by causing a bead apex to rise to a bead part, reducing rigidity of the central part of a tread part to a value smaller than that of a shoulder part, and reducing the cornering power of the central part to a value lower than that of the shoulder part. CONSTITUTION:A winding-up height Ht of a winding-up part 6b of a carcass 6 of a tire 1 from a bead bottom 15 is set to a value 1.0-1.2 times as large as a tread edge height Hs of a tread part 2 from bead bottom 15 of edges E1 and E2 of a tread part 2. A belt layer 7 is formed such that a beltlike and long narrow ply is wound around the outside of the carcass 6, the fibers of Nylon 66 are used for a belt cord, and helically wound at a low angle with a tire equator C. A bead apex 9 is formed of relatively soft rubber having JISA hardness of 50-65 deg.. A terminal H of rubber is arranged inside a 1/4 point P separated from the tire equator C by a distance 0.25 timed as long as a tread width WT and outside 1/8 point Q separated from the tire equator C by a distance being 0.125 times as long as the tread width WT.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radial tire for a motorcycle that can improve straight running performance and turning stability during high-speed running.

[Conventional technology]

In recent years, with the development of expressway networks, the demand for high-speed driving is increasing even for motorcycles.

For such radial tires for motorcycles,
Conventionally, tires have been designed and manufactured based on radial tires for four-wheeled vehicles, so they cannot match the turning performance and straight-line performance characteristic of two-wheeled vehicles, and their handling stability is particularly poor at high speeds.

The reason for this is that the belt layer a conventionally provided for reinforcing the tread portion is
As shown in the figure, the code b is 15~
The heald layer 3 with the cord b inclined in this way is arranged so that the cord b extends along the lengthwise direction of the belt d, for example, as shown in FIG. 5 (bl). A bright spot is formed according to the inclination angle α of I″b to form a parallelogram-shaped block e, and the edge f of the block 8,
It was formed into a band-like shape by aligning the f's and connecting them in a series.

The belt layer a formed in this way has the abutting portions f, f
Since the wheels pass diagonally to the direction of tire rotation, the abutting parts do not land at the same time when driving, making handling operations unstable and hindering straight-line performance. Handling performance is also poor when turning, especially at high speeds. These effects are most noticeable when driving.

In order to solve part of the above problems, for example, Utility Model Application No. 58-1
In Japanese Patent No. 60805, it is proposed that a belt layer can be formed by spirally winding a belt cord in the tire equator direction so that a belt layer does not appear in a direction crossing the running direction of the tire.

[Problem to be solved by the invention]

However, in the above-mentioned proposal, the steering stability at high speeds is slightly improved due to the elimination of rigid faults in the tread, but the sidewall and bead portions that form the sidewalls of the tire are not improved. Especially in motorcycles that run with a large camber angle when turning, there is a problem of insufficient grip when turning.

Furthermore, when driving straight at high speed, the cornering power becomes large, causing vibration of the vehicle body induced from the road surface, that is, a riding phenomenon, which impedes higher speeds.

As a result of intensive research to solve the above problems, the inventors found that
By raising the bead apex to the bead, making the center part of the tread less rigid than the shoulder part, and lowering the cornering power in the center part than in the shoulder part, straight-line running performance and cornering performance are improved. On the other hand, by forming the belt layer with a narrow ply using a belt cord made of nylon 66 by spiral winding, the movement of the tip of the bead apex caused by tire running and the I! They discovered that it can prevent 11 distances and improve high speed and durability.

An object of the present invention is to provide a radial tire for a motorcycle that can improve steering stability when traveling straight at high speed and when turning at high speed, and can solve the above-mentioned problems by increasing durability and scaling.

[Problem to be solved by the invention]

The present invention has a main body extending from the tread part through the sidewall part to the bead part, and a winding part connected to the main body part and folded around the bead core of the bead part, and at an angle of 70 to 90 degrees with respect to the tire equator. A belt layer consisting of a carcass using one or more carcass plies having a carcass cord made of S-bearing fibers inclined at a tread portion and one or more belt plies disposed inside the tread portion and outside the carcass in the radial direction. and a bead apex extending outward from the bead core in the tire radial direction and between the main body part and the winding part and between the main body part and the belt layer, and the winding part has a winding height from the bottom surface of the bead. difference(
Ht) is 1.0 times or more and 1.5 times or less the tread edge height (Hs) of the edge of the tread portion from the bottom surface of the bead, and the belt bridle is a belt cord made of wI coarse nylon 66. The bead apex is formed by winding a belt-like long narrow braise embedded in the tread rubber at a small angle with respect to the tire equator, while the bead apex is made of rubber with a JISA hardness of 50 to 65 degrees. At the same time, the end of the rubber is 0.2 of the tread width (WT), which is the distance from the tire equator to the edge of the tread.
This is a radial tire for a motorcycle, which is located inward in the tire axial direction from a 1/4 point separating 5 times the tread width (TW) and axially outward from a 1/8 point separating 1.25 times the tread width (TW). .

[Effect]

The carcass code of the carcass is 70~ relative to the tire equator.
90" and the belt cord of the belt layer is wound at a small angle with respect to the tire equator,
The carcass cord and the belt cord intersect to form a threaded shape, exhibiting a hoop effect and increasing the rigidity of the tread portion.

In addition, since the belt layer is formed by winding a narrow belt ply in which the belt cord is embedded in the topping rubber, the belt layer is inclined with respect to the tire equator like the conventional belt layer shown in Fig. 5 (al). There is no seam in direction, which improves steering stability when going straight and turning.

In addition, since the belt cord was formed using nylon 66 ism, nylon 66 has higher tensile strength and elastic elongation than steel and other organic fibers, so the tip of the bead apex can be securely pressed between the carcass and the bead apex. This prevents the tip of the bead apex from moving and prevents the end of the belt layer from peeling off, thereby further improving the durability of the bead.

Further, in the sidewall portion and bead portion, the winding height Ht of the carcass winding portion is made larger than the tread edge height Hs, so that the rigidity of the sidewall portion can be increased.

In addition, the bead apex passes between the main body part and the winding part of the carcass, extends between the main body part and the belt layer, and has its terminal end located between the 1/4 point and the 1/8 point. The bead apex allows the bead portion, sidewall portion, and shoulder portion of the bead portion to be continuously reinforced without generating rigid faults, thereby increasing rigidity. Furthermore, since the rubber hardness of the bead apex is lower than that of conventional bead apex, in the JISA hardness range of 50 to 65 degrees, elasticity can be imparted to the bead portion and sidewall portion even when the bead apex is set up.

The bead apex formed in this way is organically combined with the structure of the winding part of the carcass, and the rigidity of the central part of the tread part is lower than that of the shoulder part, and cornering power can be lowered when traveling straight at high speed. It can suppress the weaving phenomenon that tends to occur when driving straight at high speeds, improve driving stability when driving straight at high speeds, and improve cornering as the camber angle increases when turning with a camber angle. Power increases gradually, especially with camber
When the angle is in the range of 20 to 40 degrees, cornering power is effectively increased, resulting in improved grip during turning, and high-speed turning performance.

In this manner, the present invention integrates each of the above-mentioned components, and can improve both straight-line performance and turning performance during high-speed running, and can also improve steering stability.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, 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 portion 4 located at the inner end of the sidewall portion 3 in the tire radial direction. The length between the edges E1 and 82 of the tread portion 2 is determined by the maximum weight. Further, the radial motorcycle tire 1 is provided with a winding part 6b that winds up the bead core 5 from the inner side to the outer side in the axial direction of the tire, on the main body part 6a extending from the tread part 2 through the sidewall part 3 to the repeat part 4. a carcass 6, and a belt layer 7 disposed inside the tread portion 2 and outside the carcass 6 in the radial direction. The main body portion 6a passes between
A bead apex 9 extending between the belt layer 7 and the belt layer 7 is raised.

The carcass 5 is made of one or more carcass plies, in this example, one carcass ply, which has a radially arranged carcass cord inclined at an angle of 70 to 90 degrees with respect to the tire equator C, and the carcass cord is made of nylon, Conventional fiber cords such as rayon, polyester, aromatic polyaramid, etc. are used.

The winding portion 6a has a winding height Ht from the bead bottom surface 15 that is at least 1.0 times the tread edge height Hs from the bead bottom surface 15 of the end edges El and E2 of the tread portion 2, and 1.
It is set to be less than twice that.

If the winding height Ht is less than 1.0 times the tread edge height Hs, the bending stress acting on the bead portion 4 cannot be absorbed and the rigidity of the bead portion 4 is insufficient, resulting in a decrease in durability. , exceeds 1.2 times, the rigidity of the tread shoulder portion SH increases and the ride comfort during cornering decreases.

Further, in this embodiment, the winding portion 6b has an overlapping portion 16 that overlaps both side portions of the belt layer 7 at the terminal end thereof. By providing such an overlapping part 16, movement of the carcass due to tire deformation can be prevented, and IIIM of the carcass 6@ part can be prevented.
prevents this and improves tire durability. Note that the overlap part 15
The overlapping length shall be 10 meters or more and 20 meters or less. If the length is less than 10, the carcass 6 will be misaligned, and if it is 20 or more, the cost will be high.

The belt layer 7 is formed by wrapping a strip-shaped and long narrow ply lO around the outside of the carcass 6.

Small braai! 0 is one line or flat i〒 as shown in Figure 2.
A plurality of belt cords 11, two in this embodiment, are arranged in the belt cord 11.
is embedded in the topping rubber 12, and the belt cord 11 is made of nylon 66 fiber.

Nylon 66, steel and other materials
It has both high tensile strength and high initial elastic elongation compared to the above-mentioned high tensile strength and high initial elastic elongation. By carcass 6, bead apex 9
It is possible to forcefully press the tip of the holder to prevent its movement.

Also, nylon 66 has higher heat resistance than nylon 6.
Therefore, even if the tread portion becomes overripe due to high-speed running, there is little deterioration, making it suitable as a belt cord for high-speed running.

Further, in this embodiment, the narrow ply 10 has a flat rectangular shape,
The distance N from the side m1oa to the center of the outermost belt cord 11 is set to 1/2 or less of the pitch P between the belt cords 11 and 11.

In this embodiment, the two-width braai 10 is arranged as shown in FIG. 3 (as shown by the arrow in FIG. One of the braai pieces 7a is formed by winding it in a spiral shape toward the tire equator C and at a small angle with respect to the tire equator C, with the end point G near the tire equator C. When wrapping the width ply 10,
As shown in FIG. 4, the adjacent side edges 10a and the vicinity of 10a are wrapped and wound. Therefore, it is possible to prevent the narrow width ply 10 from loosening at the starting point, and also to prevent the narrow width ply 10 from peeling off at the edge of the belt layer 7 where a large force is applied during running.

Further, in this embodiment, the narrow ply 10 is attached to the other tread end E.
The one ply piece 7b is wound toward the tire equator C using a point located on the outside of the carcass 6 near the second ply piece 7b as a base point F2.
The other ply piece 7b extending near the end point G is formed.

The other ply piece 7b is wound with a narrow ply 10 in a direction opposite to the one ply piece 7a with respect to the tire equator C and inclined at the same angle as one belt braai.

When the ply pieces 7a and 7b are formed by two ply pieces 7a and 7b whose inclination angles are opposite to each other as in this embodiment, it becomes possible to wrap two narrow plies 10 and 10 on the carcass 6 at the same time, and in a short time. Thus, two ply pieces 7a, 7b can be formed.

On the other hand, since the other ply pieces 7a and 7b are wound starting at both end edges F1 and F2 of the belt layer 7, the winding starting point of the narrow width braai 10 is firmly fixed and the winding end ends close to the belt. Since it is not located at the edge of layer 7,
It is possible to prevent the belt layer 7 from becoming loose from the end of the winding.

On the other hand, the other ply pieces 7a and 7b are the narrow ply 1.
0 may be aligned in the same direction, and the belt layer 7 can also be formed by winding a single narrow braai 10 starting from one end edge of the belt layer 7 and ending at the other end. be able to.

The width of the belt layer 7 in the tire axial direction is the width of the tread portion 2.
It is preferable that the distance between the end edges E1.82 of the tread width WT be 0.7 times or more and 1.0 times or less.

The Bead Apex 9 has a JiSA hardness of 50 to 6.
It is formed of relatively soft rubber with a diameter of 5 degrees, and the terminal end H of the rubber is located inside a 1/4 point P that is separated from the tire equator C by 0.25 times the tread width WT, and at 0 of the tread width WT. 1/ separating .125 times from tire equator C
It is located outside of point 8 Q.

If the rubber hardness is less than 50 degrees, the rigidity of the bead portion 4 and sidewall portion 3 will be insufficient, and the steering stability during straight running and turning will be poor, such as bending of the bead portion 4. On the other hand, if it exceeds 65 degrees, the rigidity will be poor. is high, resulting in poor handling.

In addition, if the terminal end K of the bead apex 9 is located outside the 1/4 point P, the rigidity reinforcement of the tread portion 2 will be incomplete, and weaving is likely to occur when traveling straight at high speed, and camber When turning at an angle, cornering power is insufficient and grip is reduced. On the contrary, the above 1
If the end point K is located closer to the tire equator than the /8 point, the rigidity of the central part of the tread near the tire equator C becomes excessive, cornering power increases, and high-speed running performance deteriorates.

〔Concrete example〕

A tire with a tire size of 170/60VR17 has the configuration shown in Figure 1 and the specifications shown in Table 1 (Specific Example 1).
, 2.3) was prototyped and tested. For comparison, tests were also conducted on conventional tires (Comparative Examples 1 and 2) manufactured according to specifications other than those of the present invention.

The test conditions are as follows.

■) High-speed straight-line stability, high-speed cornering stability A trial tire was attached to the rear wheel of a motorcycle, and the motorcycle was run on a test road at 200 to 270 kmr/Hr, and evaluated by the test driver's feeling. The numerical values in the table are expressed with Comparative Example 1 as 100. The larger the value, the better.

In addition, for the test run, the front wheels in both the specific example and the comparative example had a tire size of 120/70R/17, and the belt layer had a structure consisting of a sheet braai as shown in Figure 5 (a), and a conventional tire size as shown in Table 2. Tires with specifications were installed.

As a result of the test, it was found that the specific example was superior to the comparative example in each test item.

〔Effect of the invention〕

The radial tire for motorcycles of the present invention is as follows:
The above-mentioned configurations are organically integrated, and when going straight at high speed, the cornering power can be lowered to prevent weave, and when turning with a camber angle, the cornering power increases as the camber angle increases. By gradually increasing the cornering power, particularly in the camber angle range of 20 to 40 degrees, the cornering power can be effectively increased, thereby improving grip during turning and improving high-speed turning performance.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the flow side of the present invention, Fig. 2 is a perspective view showing an example of the narrow ply, Fig. 3 is a sectional view showing the winding of the narrow ply, and Fig. The figure is a cross-sectional view showing the heald layer, and FIG.
- bead part, 5- bead core, 6- carcass, 6a- main body part, 6b-- winding part, 7- belt layer, 9- bead apex, 10- width ply, 11- belt cord, 12-. -Topping rubber, 16-overlapping part, C-tire equator, El, E2 one edge, Hs-
Tread edge height, H - winding height, K - end, P - 1/4 point, Q - 178 point, WT - tread width. 21st!1 1g4 Figure 5! ! (a) Toku 5-dong (b) 312th floor

Claims (1)

[Scope of Claims] 1. A main body extending from the tread through the sidewall to the bead, and a winding part continuous to the main body and folded around the bead core of the bead, and having a diameter of 70 to 90 with respect to the tire equator. A carcass consisting of one or more carcass plies having a carcass cord made of organic fibers inclined at an angle of 100 degrees, and one or more belt plies disposed inside the tread portion and radially outward of the carcass. a belt layer; and a bead apex extending outward in the tire radial direction from the bead core and between the main body and the winding part, and the winding part extends from the bottom surface of the bead. Hoisting height (Ht)
1.0 times or more and 1.5 times or less the tread edge height (Hs) of the edge of the tread portion from the bottom surface of the bead,
The belt ply is formed by winding a belt cord made of nylon 66 fibers embedded in the tread rubber and winding the belt cord at a small angle with respect to the tire equator. Apex is
Made of rubber with a JISA hardness of 50 to 65 degrees,
The end of the rubber is located inward in the tire axial direction from a 1/4 point that is separated from the tire equator by 0.25 times the tread width (WT), which is the distance between the edges of the tread portion, and at the tread width (WT). A radial tire for a motorcycle that is located axially outside of the 1/8 point that separates 0.125 times the tire. 2. The radial tire for a motorcycle according to claim 1, wherein the carcass has an overlapping part in a rolled-up part thereof that overlaps with the belt layer.