JPH11222007A - Pneumatic bias tire for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve road holding and operational stability by achieving reconciliation of conflicting properties of rigidity and flexibility of a tire case. SOLUTION: In a pneumatic bias tire for a motorcycle, cords of a first and second carcass plies 5, 6 in a product tire comprise cords using organic fibers of the initial tensile resistance 18-617 cN/dtex, and the first and second carcass ply cords are inclined in the opposite direction to the tire equator between the ply layers and have angles 20 deg.-40 deg. to the tire equator in the central region of a tire crown. A count in the central region of the tire crown of the first and second carcass ply cords is 30-70/5 cm when measuring in the right angle direction and the difference of the constant-load intermediate elongation is 1.0-10.0%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic bias tire for a motorcycle having excellent steering stability, and more particularly, to a ground contact tire capable of achieving both required tire case rigidity and tire case flexibility, which are mutually contradictory characteristics. The present invention relates to a pneumatic bias tire for a motorcycle, which further enhances steering performance and improves steering stability.

[0002]

2. Description of the Related Art Generally, in a bias tire structure of a pneumatic bias tire for a motorcycle, a carcass cord is arranged in a cross between carcass plies, and a ply steer phenomenon accompanying the bias arrangement of the cord is generally caused between the plies. Generally, a plurality of carcass plies are provided to cancel each other.

Conventionally, such a plurality of carcass plies are formed of the same material, and there has been no carcass ply having a difference in the material characteristics of the carcass cords or different carcass cord types.

[0004]

As described above, when a plurality of carcass plies of a pneumatic bias tire for a motorcycle are all formed of only the same kind of cord, for example, the material of the carcass ply cord is changed due to a slight level of machine performance. Must be switched in units of a plurality of high or low stiffness units, and in this case, there is a problem that it is difficult to adjust the tire case stiffness in accordance with the slight performance difference between them. Was. In particular, it has been difficult to achieve the conflicting characteristics of providing appropriate tire case flexibility on the one hand while maintaining tire case stiffness and on the other hand vibration absorption from the road surface.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic bias tire for a motorcycle in which the opposite characteristics of tire case stiffness and tire case flexibility can be achieved at the same time to further improve the contact property and improve the steering stability. It is in.

[0006]

The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, has determined a predetermined characteristic difference between carcass plies by appropriately selecting the designer himself according to the required characteristics required for the target tire. The characteristics of the two materials between the carcass plies cooperate complementarily with each other to maintain the required tire case rigidity, while maintaining the appropriate tire case flexibility against vibration absorption from the road surface Have been found, and the present invention has been completed.

That is, a pneumatic bias tire for a motorcycle according to the present invention comprises: a first carcass ply which is turned from the inside to the outside around a core of a bead portion from a tread portion to a sidewall portion, and the first carcass ply. Motorcycle air having a carcass layer formed by at least two carcass plies with a second carcass ply disposed outside the ply in the tire radial direction and extending from the tread portion through the sidewall portion to at least the vicinity of the bead core. In the biased tire, the cords of the first and second carcass plies in the product tire are both cords using organic fibers having an initial tensile resistance of 18 to 617 cN / dtex, and the first and second carcass plies are used. The cords incline in opposite directions with respect to the tire equator between the ply layers At the same time, the angle with respect to the tire equator in the central region of the tire crown is 20 ° to 40 °, and the number of hits of the first and second carcass ply cords in the central region of the tire crown is measured at right angles to the cord. The value is 30 to 70 pieces / 5 cm, and the difference in constant load intermediate elongation is 1.0 to 10.0%.

[0008] Preferably, at least one layer of a breaker cord disposed in the tire crown region adjacent to the carcass layer in the tire radial direction is made of an organic fiber having an initial tensile resistance of 18 to 617 cN / dtex in a product tire. When the breaker cord has an angle of 20 ° to 40 ° with respect to the tire equator in the tire crown central region of the breaker cord, and the number of hits in the tire crown central region of the breaker cord is measured in a direction perpendicular to the cord. The value is 30 to 70 lines / 5 cm.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the left half section of the tire shown in FIG. FIG.
The pneumatic bias tire for a motorcycle according to the embodiment of the present invention shown in FIG. 1 includes a first carcass ply 5 that turns around the core 4 of the bead portion 1 from the tread portion 3 through the sidewall portion 2 to the outside from the inside. And a second carcass ply 6, which is arranged radially outside of the first carcass ply 5 in the tire radial direction, passes through the tread portion 3, passes through the sidewall portion 2, and is similarly folded around the bead core 4. It has a carcass layer to be formed. In the present invention, the number of carcass plies may be two or more, and the second carcass ply 6 extends near the bead core 4 without folding around the bead core 4 as described above. Just do it.

In the present invention, the cords of the first and second carcass plies 5 and 6 in the product tire are both cords using organic fibers having an initial tensile resistance of 18 to 617 cN / dtex. This value is 18 cN / dt
If it is less than ex, the rigidity is insufficient and tire performance in a real vehicle cannot be satisfied. On the other hand, if it exceeds 617 cN / dtex, vibration absorption is deteriorated due to excessive rigidity, and tire performance in a real vehicle is also satisfied. Can not. Here, the "initial tensile resistance" is a value determined in accordance with 7.8 of JIS L1017 (Testing method for chemical fiber tire cord).

However, the mutual magnification of the initial tensile resistance between the carcass plies 5 and 6 is preferably 2 to 6 times, and if less than 2 times, the mutual complementation of the rigidity and flexibility between the carcass plies which is the object of the present invention. On the other hand, if it exceeds 6 times, the rigidity difference between the carcass plies is too large, which may cause interlayer separation failure or the like, resulting in poor durability.

The cords of the first and second carcass plies 5, 6 are inclined in opposite directions with respect to the tire equator between the ply layers, and have an angle of 20 ° to 40 ° with respect to the tire equator in the central region of the tire crown. It is. If this angle is less than 20 °, the rigidity is too high, while if it is more than 40 °, the rigidity is too low to ensure the actual vehicle performance.

Further, the first and second carcass plies 5,
When the number of hits of the cord No. 6 in the central region of the tire crown was measured in a direction perpendicular to the cord, the value was 30 to
It is within the range of 70 lines / 5 cm. This value is 30 lines / 5c
If it is less than m, the safety factor and rigidity are insufficient, while 70/5
If it exceeds cm, the code interval becomes too narrow, and separation failure is likely to occur.

Further, the difference in the constant load intermediate elongation between the cords of the first and second carcass plies 5, 6 is set to 1.0 to 1
Within the range of 0.0%. If this difference is less than 1.0%, the vibration absorption will deteriorate, while if it exceeds 10.0%, the case rigidity will be insufficient. Here, the "constant load intermediate elongation" refers to a constant load W measured in accordance with the constant load elongation described in 7.7 of JIS L1017 (Test method for chemical fiber tire cord). It is the elongation rate (%) at the time, and is performed based on the standard time test of 7.7.1. Here, the constant load W is calculated by the following equation: W (kgf) = 4.5 × (d2 / d1) (where d1 is a reference denier determined by the type of fiber, and d2 is a display denier of the sample). It is stipulated that the test is performed 10 times and the average value is calculated to one decimal place.

In the pneumatic bias tire for a motorcycle according to the embodiment of the present invention shown in FIG. 1, a single layer breaker 7 is disposed in a tire crown region adjacent to a carcass layer on a radially outer side of the carcass layer. I have. In the present invention, the number of breakers may be plural. The cord of the arranged single-layer breaker is preferably a cord using an organic fiber having an initial tensile resistance of 18 to 617 cN / dtex in the product tire for the same reason as the cord of the carcass ply.

The angle of the breaker cord with respect to the tire equator in the central region of the tire crown is preferably 20 ° to 40 °, and the number of hits of the breaker cord in the central region of the tire crown is measured in a direction perpendicular to the cord. Value is preferably 30 to 7
It is 0 / 5cm.

The organic fiber cord suitably applicable to the carcass ply and the breaker of the tire of the present invention includes at least polyamide (for example, nylon), polyethylene terephthalate (PET), PEN, aramid (for example, Kevler, trade name) ), Organic fibers such as rayon, and those having material properties comparable to those of these fiber materials. The present invention relates to the improvement of a carcass ply and a breaker of a tire as described above, and other structures and materials can be appropriately selected according to common use.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. As an example of the present invention and a comparative example (conventional example), under the conditions of a carcass and a breaker shown in Table 1 (Example) and Table 2 (Comparative Example), a motorcycle bias tire (size: MCS110) shown in FIG. / 90-17). Note that the angles in the table are angles with respect to the tire equator, and the first carcass ply and the second carcass ply have a cross arrangement in which the layers are mutually inclined in opposite directions with respect to the tire equator.

[0019]

[Table 1]

[0020]

[Table 2]

The tires of the example and the comparative example were mounted on a motorcycle, respectively, and a skilled driver evaluated the feeling of the actual vehicle on a test course to evaluate the speed of vibration reduction after passing through a road gap.
The comparative example tires were set to 100 and indexed. The results obtained are shown in Table 3 below.

[0022]

[Table 3]

[0023]

As described above, in the present invention, the characteristics of the two materials between the carcass plies cooperate complementarily with each other to maintain the required tire case rigidity.
Suitable tire case flexibility can be imparted also to vibration absorption from the road surface, and as a result, the ground contact property is further improved, and the steering stability is improved.

[Brief description of the drawings]

FIG. 1 is a left half sectional view of a pneumatic bias tire for a motorcycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Bead core 5 First carcass ply 6 Second carcass ply 7 Breaker

Claims (2)

[Claims] 1. A first carcass ply that is folded from the inside to the outside around a core of a bead portion through a sidewall portion from a tread portion to a bead portion, and a first carcass ply is disposed radially outside of the first carcass ply in a tire radial direction. A pneumatic bias tire for a motorcycle, comprising a carcass layer formed by at least two carcass plies with a second carcass ply extending at least in the vicinity of the bead core through a sidewall portion, The cords of the second carcass ply both have an initial tensile resistance of 18 to 617 cN.
/ Dtex comprising a cord using an organic fiber, and wherein the first and second carcass ply cords are mutually inclined in opposite directions to the tire equator between the ply layers,
The angle with respect to the tire equator in the central region of the tire crown is 20 ° to 40 °, and the value obtained when the number of hits of the first and second carcass ply cords in the central region of the tire crown is measured in a direction perpendicular to the cord is 30 ~
70 pieces / 5cm, and the difference of constant load middle elongation is 1.0
A pneumatic bias tire for a motorcycle, characterized in that the tire has a tire content of up to 10.0%. 2. At least one of the carcass layers disposed in a tire crown region adjacent to a radially outer side of the carcass layer.
The breaker cord of the layer comprises cords using organic fibers having an initial tensile resistance of 18 to 617 cN / dtex in the product tire, and the angle of the breaker cord with respect to the tire equator in the central region of the tire crown is from 20 ° to 20 °.
2. The pneumatic bias tire for a motorcycle according to claim 1, wherein a value obtained by measuring the number of shots of the breaker cord in the central region of the tire crown at 40 [deg.] In a direction perpendicular to the cord is 30 to 70 pieces / 5 cm.