JP3464184B2 - Motorcycle tires - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle tire capable of improving straight running stability and turning maneuverability at high speed and having excellent productivity.

[0002]

2. Description of the Related Art With the recent development of highway networks and higher performance of vehicles, even motorcycle tires are required to have stability and durability at high speeds. In order to improve the stability and durability during high-speed running, for example, as shown in FIG. 2, a breaker layer c having a cord is arranged on the outer side in the tire radial direction of a carcass a having a radial structure, and the carcass a is tightened with a tag. As a result, the rigidity of the tread portion b is increased. For the breaker layer c, usually two breaker plies c1 and c2 having different widths in the tire axial direction are used, and the width center of each ply in the tire axial direction is aligned with the tire equator C and the cords intersect each other. They are arranged so that they will be stacked. Further, the breaker layer c is provided with breaker plies c1 and c in order to prevent stress concentration at both ends thereof.
Step S is formed by changing the position of the outer end of 2.

[0003]

However, in the conventional breaker layer c, in order to form the step S, it is necessary to prepare at least two types of breaker plies c1 and c2. This preparation requires adjustment of the cutting width when cutting the breaker plies, and the number of ply feeders (molding machine servicer) is two in order to send breaker plies of different widths to the tire molding machine. There is a problem in that the production equipment becomes complicated and the equipment cost rises due to the necessity.

Further, if the rigidity of the tread portion of the tire is excessively increased, the tire has a large cornering power, and there is a problem that the running stability of the motorcycle tire is deteriorated. That is, in a motorcycle, a slight slip angle may occur in the tire even when traveling straight, but in this case as well, cornering power in the direction perpendicular to the traveling direction is generated in the tire, resulting in a so-called weave phenomenon in which the vehicle body vibrates laterally. When the vehicle is traveling at high speed, the running stability tends to decrease.

The present invention has been made in view of the above problems, and has two equal-width plies in which tire widths Wa and Wb in the tire axial direction are substantially the same, and these width-wise plies are the same. Provide a motorcycle tire that can be manufactured efficiently and that can reduce manufacturing costs, based on the use of breaker layers whose centers are opposite to each other from the tire equator and displaced in the tire axial direction at approximately the same distance. For the purpose of
Furthermore, while using plies with the same width, it is possible to easily adjust and optimize the tag tightening effect by the breaker layer and provide a motorcycle tire that can improve running stability at high speeds etc. The purpose is to do.

[0006]

According to a first aspect of the present invention, the tread width, which is the distance between the tread edges in the tire axial direction, has the maximum tire width, and the tread surface is convex outward in the tire radial direction. A motorcycle tire having a curved tread portion in an arc shape, a carcass extending from the tread portion to a bead core of a bead portion through a sidewall portion, and a tire radial direction outer side of the carcass and inside the tread portion. And a breaker layer disposed on the breaker layer, the breaker layer including at least two equal width plies having tire widths Wa and Wb substantially the same in the tire axial direction, and the two equal width plies have respective widths. Since the center of direction is opposite from the equator of the tire and is displaced by the same distance Z in the tire axial direction, the equal width plies are weighted in the tire radial direction inside and outside in the central portion. Comprising a ply overlapping portion that, the non-overlapping portion not overlapping contiguous with such width ply on both sides, the
The tire axial width W2 of the ply overlapping portion is equal to the above breaker.
The layer width is 40 to 80% of the axial width W1 of the tire .

In such a motorcycle tire, the breaker layer has tire widths Wa and Wb that are substantially the same.
By including one equal-width ply, the ply can be supplied by one ply feeder, and the ply can be cut with one kind of width, resulting in simplification of production equipment and reduction in manufacturing cost. Can be reduced.

Further, the breaker layer can be easily adjusted by optimizing the effect of the breaker layer on the carcass by properly setting the width of the ply overlapping portion while using plies having the same width. Therefore, it is possible to easily improve stability, durability and the like when traveling at high speed.
In this case, the tire axial width W2 of the ply overlapping portion is particularly preferably 40 to 80% of the tire axial width W1 of the breaker layer.

Further, the breaker layer has a tire radial direction distance Bh between the outer end in the tire axial direction and the tread edge, the tire radius from the tread edge to the tire radial outermost position of the tread surface. It is desirable to be 20% or less of the tread height Th which is the directional distance. As a result, the breaker layer can be reinforced on the end side of the tread surface that comes into contact with the ground in a full bank state during turning, and as a result, stability during turning can be further ensured.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a motorcycle tire (hereinafter, may be simply referred to as “tire”) 1 of the present embodiment.
FIG. In the figure, a tire 1 has a tread portion in which a tread width TW, which is a distance in the tire axial direction between the tread edges E, has a maximum tire width, and a tread surface 2S is curved in an arc shape protruding outward in a tire radial direction. Have two. Further, the tire 1 includes a carcass 6 extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3, and a breaker layer 7 arranged outside the carcass 6 in the tire radial direction and inside the tread portion 2. It is equipped with

The carcass 6 has, for example, a bead core 5 of a bead portion 4 extending from a tread portion 2 to a sidewall portion 3.
On both sides of the ply body 6a up to the position where the bead core 5 is wound from the inner side to the outer side in the tire axial direction.
It is configured to include one or more carcass plies 6A having the above, and forms a skeleton of the tire. Further, for example, for heavy vehicles, the number of carcass plies 6A can be increased, and further, various aspects can be changed as necessary, such as extending the outer end of the winding portion 6b to a position covering the breaker layer 7. .

In the carcass ply 6A, the carcass cord is 75 to 90 with respect to the tire equator C in this example.
A radial structure tilted at an angle of degrees is used, and as the carcass cord, an organic fiber cord such as nylon, rayon or polyester is preferably used. The carcass ply 6A is exemplified by a bead apex rubber 8 having a triangular cross section extending from the bead core 5 to the tire radial direction outer side between the ply body 6a and the winding portion 6b.

In this embodiment, the breaker layer 7 is composed of at least two equal width plies 7a and 7b having substantially the same widths Wa and Wb in the tire axial direction. The two equal-width plies 7a and 7b have respective width-direction centers Ca and Cb.
Are displaced from the tire equator C in mutually opposite directions and at substantially the same distance Z in the tire axial direction. This allows the breaker layer 7
Has a ply overlapping portion 9 where the equal width plies 7a and 7b overlap in the tire radial direction inside and outside in the central portion, and a non-overlapping portion 10 where the equal width plies 7a and 7b are continuous and which do not overlap. .

The equal-width plies 7a and 7b are plies in which, for example, organic fiber cords are arranged at a small angle of, for example, 15 to 35 degrees with respect to the tire equator C, and both surfaces are covered with topping rubber. , The cords of the equal-width plies 7a and 7b intersect at the ply overlapping portion 9, and the same ply is used in this example. The same ply means substantially the same ply cord material, cord angle, number of cords to be driven, and topping rubber. Such equal-width plies 7a and 7b can be continuously cut with a constant width by, for example, a ply cutting machine, so that it is not necessary to cut plies of a plurality of kinds of widths by changing the cutting width and productivity is improved. Further, since the equal width plies 7a and 7b have the same width, it is possible to supply the plies to the tire molding apparatus by using one ply supply device, which is useful for simplifying the production equipment.

Further, the breaker layer 7 uses plies having the same width, but by appropriately setting the width W2 of the ply overlapping portion 9, the effect of the breaker layer 7 on the carcass can be easily adjusted. Can be optimized. That is, the width W2 of the ply overlapping portion 9 is relatively increased to increase the rigidity of the tread portion 2, and conversely, the width W2 of the ply overlapping portion 9 is relatively decreased to weaken the rigidity of the tread portion 2. Therefore, it is possible to easily set and improve the stability, durability, etc. when traveling at high speed as required.

Further, the width center lines Ca and Cb of the equal-width plies 7a and 7b are opposite to each other with respect to the tire equator C and are displaced from each other by substantially the same distance Z in the tire axial direction. In addition to arranging the ply overlapping portion 9 in the center of the tire, it becomes possible to secure the substantial symmetry of the tire. In addition, such a breaker layer 7 has a non-overlapping portion 10
2 is also greatly different from the breaker layer shown in FIG. 2 in that the cords of the equal-width plies 7a and 7b incline in the same direction with respect to the tire rotation direction. In particular, for a motorcycle tire that gives a camber angle to the tire and runs with the tread side end contacting the ground, by including such a breaker layer 7, the amount of camber thrust generated with respect to the camber angle can be turned left and right. Is almost uniform, and stability during turning can be further improved.

If the width W2 of the ply overlapping portion 9 in the tire axial direction is too small, the force of the breaker layer 7 to restrain the carcass 6 is insufficient, and high-speed durability tends to be relatively low. The steering stability tends to decrease due to the decrease in rigidity. On the contrary, if the width W2 of the ply overlapping portion 9 in the axial direction of the tire is too large, the weight of the tire becomes heavy and the rigidity of the tread portion 2 tends to be relatively increased. From such a viewpoint, the tire axial width W2 of the ply overlapping portion 9 is the tire axial width W1 of the breaker layer 7.
By setting it to 40 to 80%, more preferably 40 to 50%, it is possible to more reliably improve the stability, durability and the like during high speed running.

Further, the breaker layer 7 is formed over the arc width of substantially the entire region of the tread portion 2 in this example, thereby protecting the carcass 6 in a wide range and reinforcing it with a hoop effect. Further, in this example, since the cords of the equal-width plies 7a and 7b are overlapped in the ply overlapping portion 9 of the breaker layer 7 in such a direction that the plies intersect each other, the carcass 6 is firmly fixed particularly in the ply overlapping portion 9. You can tighten the tag. As the cords used for the equal-width plies 7a and 7b, in addition to organic fiber cords such as nylon, rayon, polyester, and aromatic polyamide, steel cords, carbon fiber reinforced cords, and the like are preferable if necessary.

The breaker layer 7 preferably has a tire radial direction distance Bh between the outer end 9e in the tire axial direction and the tread edge E of 20% or less of the tread height Th. Here, the tread height Th is a tire radial direction distance from the tread edge E to the tire radial outermost position P of the tread surface 2S. In this way, by controlling the position of the outer end 7e of the breaker layer 7, the tread surface 2S grounded in the full bank state during turning.
As a result of being able to reinforce with the breaker layer 7 also on the end side of
The stability during turning is further ensured.

Although the embodiment of the present invention has been described above, for example, the breaker layer 7 may be composed of three or more plies. In this case, the other one ply may have the same width as or different widths from the equal-width plies 7a and 7b. However, in order to ensure the symmetry of the tire, the plies other than the equal-width plies 7a and 7b are used. Regarding the ply, it is preferable that the center of the width of the ply is aligned with the tire equator C. Further, the present invention can be applied to various forms such as being applicable to a so-called cut breaker of a motorcycle tire having a carcass having a bias structure.

[0021]

EXAMPLES Next, more specific examples of the present invention will be described. The tire size that makes the specifications shown in Table 1 is 120 /
70ZR17 radial tires for motorcycles were prototyped, and the cornering power of each trial tire,
High-speed durability and running stability (straight running, turning) were tested according to the following procedures. In addition, the tire has a radial structure carcass reinforced with two carcass plies of polyester cord as a common specification.

<Cornering Power> A test tire was tested with an indoor tester at a speed of 30 km under the conditions of rim (MT3.50 × 17), internal pressure (250 kPa) and load (1.5 kN).
Cornering power was obtained from the cornering force measured at a slip angle of 0 ° and 30 °, and the results were compared by an index with the conventional example being 100. The larger the value, the higher the cornering power.

<High-speed durability> A test tire was mounted on a bench drum tester with a rim (MT3.50 × 17) and an internal pressure (2).
90 kPa), speed 2 under the condition of load (1.13 kN)
The case of running at 70 km / h and being able to run for 10 minutes without damage was regarded as acceptable.

<Driving Stability> A test tire is used as a rim (MT
3.50 × 17), under the condition of internal pressure (250kPa), it is mounted on the front wheel of a motorcycle (750cc, 4 cycles), runs on a dry paved road, and the stability of the driver when traveling straight and turning is sensed by the driver. Evaluation was made by a 5-point method. The larger the value, the better. The test results are shown in Table 1.

[0025]

[Table 1]

As a result of the test, it was confirmed that the tires of the examples had a smaller cornering power than the conventional examples, and as a result, the running stability was also improved. Moreover, the high-speed durability was comparable to the conventional example.

[0027]

As described above, in the motorcycle tire of the present invention, the breaker layer includes two equal width plies having substantially the same width in the tire axial direction. Can be performed by one ply feeder, and cutting of these plies can be performed with one width, so that the production facility can be simplified and the tire manufacturing cost can be reduced. Also, steps can be formed while using equal width plies having the same width, and by setting the width of the ply overlapping portion appropriately, the breaker layer can easily adjust and optimize the tightening effect on the carcass. Because you can
It is easy to improve stability and durability when driving at high speed. In particular, the tire axial direction width W2 of the ply overlapping portion, and 40% to 80% of the tire axial direction width of the breaker layer
Therefore , stability, durability, etc. when traveling at high speed can be more reliably improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional tire.

[Explanation of symbols]

1 motorcycle tires 2 tread section 3 Side wall part 4 bead part 5 bead core 6 carcass 6a main body 6b Winding section 7 breaker layers 7a, 7b equal width plies 9 ply overlap 11 ply non-overlapping part C tire equator Th tread height

Continuation of the front page (56) Reference JP 58-73404 (JP, A) JP 57-66004 (JP, A) JP 58-73405 (JP, A) JP 7-132706 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 9 / 06,9 / 08,9 / 18,9 / 30

Claims (2)

(57) [Claims] 1. A motorcycle tire comprising a tread width, which is a distance between tread edges in the tire axial direction, having a maximum tire width, and a tread surface having a tread portion curved in an arc shape convex outward in a tire radial direction. There is a carcass from the tread portion through the sidewall portion to the bead core of the bead portion, and a breaker layer disposed on the tire radial direction outer side of the carcass and inside the tread portion, wherein the breaker layer is a tire. The axial widths Wa and Wb include at least two equal-width plies having substantially the same width, and the two equal-width plies have their width-direction centers opposite to each other from the tire equator and substantially in the tire axial direction. By shifting the positions by the same distance Z, the equal-width plies are overlapped in the tire radial direction in the center in the tire radial direction, and the ply overlapping portion is connected to both sides of the ply overlapping portion. Comprising a non-overlapping part b do not overlap, the tire axial direction width W2 of the ply overlapping portion, the blurring
A tire for a motorcycle , wherein the width of the tire layer in the axial direction of the tire layer is 40 to 80% . 2. A distance Bh in the tire radial direction between an outer end of the breaker layer in the tire axial direction and the tread edge.
The tire for a motorcycle according to claim 1 , wherein is 20% or less of a tread height Th that is a tire radial direction distance from the tread edge to a tire radial outermost position of the tread surface.