JPH0655906A - Tire for motorbicycle - Google Patents

Abstract

PURPOSE:To enhance high speed durability, straight running stability, turn- running stability and riding comfort by composing a belt layer of plural number twist of specific fineness strands of twisted aromatic polyamide fiber, forming it of belt plies in which flat low twist cords of the specific twist number are arranged in parallel to each other. CONSTITUTION:A carcass 6 consists of carcass plies equipped with carcass cords in radial arrangement inclined by 70-90 degrees of angle to the tire equator C, and organic fiber cords are used as the carcass cords. A belt width WB of a belt layer 7 is set at 0.5-1.1 times of a tread width WT, a belt cord is formed of plural twisted strands 13 composed of aromatic polyamide fiber filaments twisted together into fineness 840d-1890d and the twist number is set to be 29 turn or less per 10cm. In a belt ply 7a, a belt-like ply of small width and long size comprising low twist cord covered with topping rubber is spirally wound to arrange the belt cords in parallel to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle capable of simultaneously satisfying the steering stability and riding comfort of tires, which have been in a contradictory relationship with each other at the same time, promoting weight reduction, and realizing low heat generation and low fuel consumption. For tires.

2. Description of the Related Art In recent years, with the improvement of the highway network and the higher performance of the vehicle body, motorcycles have improved durability against high speed running and stability during straight running and turning running. Is required. In order to meet these requirements, JP-A-1-109106 and JP-A-1091010
No. 7 has a structure in which spiral belt plies in which cords parallel to the tire equator are arranged inside or outside of two or more cross belt plies in which the belt layers are inclined in the tire circumferential direction at an inclination of 10 to 30 ° In Japanese Patent Application Laid-Open No. 1-289703, it is proposed to provide a belt layer in which highly elastic cords are arranged directly outside the radial structure carcass in parallel to the tire equator. Further, Japanese Patent Laid-Open No. 61-85203 proposes a belt layer in which a belt cord is spirally wound substantially parallel to the tire equator and is wound in opposite directions on both sides of the tire equator.

Further, in JP-A-4-15103, the belt cord is an aromatic polyamide fiber cord and the twist number is 2
It has been proposed to tilt a 0-57T / 10cm cord on the carcass at a small angle to the equator.

[0003]

However, in the above-mentioned proposal, the structure of the belt layer is complicated, the productivity is lowered and the cost is increased. There is also a method of obtaining a belt layer by a method of spirally winding a cord on a profile drum, but a manufacturing method using such a step has a problem that it takes a long time to wind the cord. Furthermore, since the belt layer wound on the profile drum is moved onto the carcass to form a raw tire and the raw tire is vulcanized in the mold, the cord is apt to be disturbed in these steps. There is also.

Further, the concavo-convex pattern provided on the tread surface is formed by putting a raw tire in a mold, inflating the raw tire and pressing the tread surface against the mold, but the cord is stretched to some extent. Otherwise, the uneven pattern will not be formed. Especially in deep patterns with unevenness,
It was necessary to further enhance the extensibility of the cord. For this reason, in most conventional motorcycle tires, high-twisted cords having a cord twist number of 30 to 57 T / 10 cm have been used.

When a belt layer is formed by using such a high twist cord, the belt cord itself has a large elongation, so that the tread portion rises due to centrifugal force during high speed running, so-called tire growth occurs. There is a problem that the durability is poor and the running stability is poor when traveling straight and turning.

Moreover, since the belt cord has a circular cross section, it is inferior in stability of work during winding, and it is difficult to make a uniform spiral winding, and unevenness is apt to occur. Was a factor that reduced the uniformity of the. Further, there is a problem that the surface on which the tightening force per cord acts is narrow and the rigidity on the outer side in the radial direction of the belt layer is insufficient. Further, there is a problem that the number of times of winding the cord is increased and the productivity is lowered.

As a result of repeated trial manufacture and experiments, the inventors of the present invention paid attention to the constitution of the belt cord itself, and as a result, flattened the twist and the cross section, and regulated the number of twists and the fineness of the strand to solve the above problems. The inventors have found that the points can be solved and completed the present invention.

The present invention improves high-speed durability as well as straight running stability, turning stability and riding comfort.
Moreover, it is an object of the present invention to provide a motorcycle which has high stability of tire dimensions and can be economically produced.

[0009]

According to the present invention, the tread width, which is the distance between the edges of the tread portion in the tire axial direction, is the maximum width of the tire, and the tread portion passes through the sidewall portion to surround the bead core of the bead portion. A toroidal carcass, and a belt layer disposed inside the tread portion and outside the carcass in the radial direction and having a width in the tire axial direction of 0.5 times or more and 1.1 times or less of the tread width. A motorcycle tire including the carcass, wherein a carcass cord made of an organic fiber is 70
The belt layer is formed by a belt ply in which belt cords are arranged in parallel while being formed by a carcass ply having a radial arrangement inclined at an angle of ˜90 °.
The belt cord is a plurality of strands of 840 to 1890d formed by twisting filaments made of aromatic polyamide fibers, and is a low twist twisted with a twist number of 29 per 10 cm or less, and in the tire axial direction. A tire for a motorcycle, comprising a cord having a flat cross-sectional shape with a longitudinal axis.

In the belt ply, the belt cords may be arranged in parallel by spirally winding a narrow width and long belt-shaped ply in which the low twist cord is covered with a topping rubber at a small angle with respect to the tire equator. preferable.

The belt cord preferably has an aspect ratio of 0.5 or more and 0.8 or less. The belt cord may be formed by twisting filaments to directly form a strand, or may be formed by twisting filaments to form a yarn and twisting a plurality of the yarns to form a strand.

[0012]

Since the carcass has a radial arrangement in which the carcass cords are inclined at an angle of 70 to 90 ° with respect to the tire equator, the rigidity of the tire as a whole is softened, and high-speed running performance is improved when straight ahead, and riding comfort is improved. Can be raised.

In the belt layer, the belt cords made of aromatic polyamide fibers are arranged in parallel on the outer side of the carcass, so that the bending rigidity of the tread portion inward in the radial direction is lowered, the grounding property is improved, and the steering stability is improved. It Aromatic polyamide fibers have high tensile strength and tensile modulus.

When the belt cords are spirally wound in parallel with each other substantially parallel to the equator and are arranged in parallel, the effect of suppressing the lifting of the carcass due to the centrifugal force due to the high speed rotation of the tire is great, so that the high speed durability is improved and the vibration is generated. Can increase speed. Further, since the rigidity of the tread contact surface is lowered, the cornering force is lowered, and the lateral sliding at the time of turning is suppressed, so that the turning stability is improved.

Moreover, the belt cord is made of a filament made of aromatic polyamide fiber and has a fineness of 840.
It is a cord of a low twist in which a plurality of strands of d or more and 1890 d or less are twisted together and the number of twists is 29 or less per 10 cm. As a result, the rigidity of the belt layer outward in the radial direction can be further increased. The number of twists is 1
More preferably, it is in the range of 24 to 29 per 0 cm.
With a single-stranded cord having a strand fineness of less than 840d, the rigidity of the belt ply is low, and high-speed durability, straight running performance, and turning performance are all deteriorated. If more than 6 strands of 1890d are twisted in multiple strands, the cord becomes too thick and the workability becomes poor, and it becomes difficult to maintain and improve the uniformity of the tire, and there is a risk that the riding comfort will deteriorate. Preferably.

Further, since the belt cord has a flat cross section whose longitudinal axis is in the tire axial direction, when the cord is spirally wound, the spiral winding pitch can be increased, and at the time of winding the belt cord. , The work becomes easier and the work efficiency can be improved. Further, since the belt cord has a flat cross section with the tire axis as the longitudinal axis as described above, when this belt cord is wound on the profile file drum, it can be stably wound and wound. Later, the uniformity of the tire is improved without disturbing the belt cord even in the treatment process during moving to the carcass to mold the green tire and vulcanize in the mold.

In addition, since the belt cords are arranged in parallel with the tire axial direction as the longitudinal axis, lateral rigidity is increased from the tread portion to the buttress portion of the sidewall portion, and the camber thrust is improved, so that the turning performance is improved. It When the belt cord is formed as a long strip-shaped ply covered with a topping rubber, the side edges of the strip-shaped ply facing each other can be widely wrapped and spirally wound to further increase the lateral rigidity. Becomes

The flatness of the belt cord (cord minor axis length / major axis length) is preferably in the range of 0.5 to 0.8. When the flatness is less than 0.5 in the cord of the fineness and the number of strands limited by the present invention, when the centrifugal force acts radially outward, the radial rigidity of the belt layer becomes small, and the lifting suppressing effect is poor. . Therefore, the high speed durability of the tire is reduced and the steering performance is reduced. On the other hand, if the flatness ratio exceeds 0.8, it becomes close to the cross-sectional shape of the conventional belt cord, the parallel work of the belt cords requires time and labor, and the cords are apt to be disturbed, which deteriorates the uniformity of the tire.

FIG. 5 shows a load-elongation curve of the cord itself formed of the organic fiber and its cord composition. Figure 5
As can be understood from the graph of Fig. 6, it was confirmed by the test results that each of the cords a, b, c and d using the aromatic polyamide fiber has higher elasticity than the cord e consisting of 66 nylon. Of.

Therefore, the belt cord is made of aromatic polyamide fiber and the fineness of the strand is 840d to 1870.
The number of twists is 29 per 10 cm.
By the following, the extensibility of the belt layer is reduced,
Since the rigidity is increased, the steering stability of the tire is improved (the low twist effect), and the flatness of a cord having a high fineness is also decreased, so that the rigidity against bending inward in the radial direction is reduced and the riding comfort is improved. Therefore, it is possible to provide a tire that simultaneously satisfies both the controllability and the riding comfort that are in the conventional trade-off relationship.

At the same time, by flattening the cord, the amount of cord used is reduced, the weight of the tire is reduced, the cost is reduced, and the total thickness of the tread portion can be reduced, so that low heat generation and low fuel consumption can be realized.

If the width of the belt layer is less than 0.5 times the tread width, the rigidity of the tread shoulder region of the tread portion may be reduced and uneven wear may occur.
If it exceeds 1.2 times and is increased, the rubber thickness of the buttress portion becomes thin and the rubber is damaged. The width of the belt layer is preferably 0.7 to 1.0 times the tread width.

As described above, according to the present invention, since the above-mentioned components are organically combined and integrated, the straight traveling stability and the turning traveling stability at the time of high speed traveling can be improved and the workability can be improved. is there.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, a motorcycle tire 1 has a tread portion 2
And a sidewall portion 3 extending from both ends thereof inward in the tire radial direction, and a bead portion 4 located at an inner end of the sidewall portion 3 in the tire radial direction, and the motorcycle tire 1 includes: Body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4
A carcass 6 in which a winding portion 6b for folding the bead core 5 from the inner side in the tire axial direction to the outer side is extended, and a belt layer 7 arranged inside the tread portion 2 and on the outer side in the radial direction of the carcass 6. In addition, in this embodiment, a bead apex 8 having a triangular cross section is raised outside the bead core 5 in the tire radial direction.

The carcass 6 is composed of at least one carcass ply having a radial array of carcass cords inclined at an angle of 70 to 90 degrees with respect to the tire equator C, and in this embodiment, one carcass ply. Is an organic fiber cord such as nylon, polyester or wholly aromatic polyamide fiber. Also, the bead bottom surface 1 at the tip of the winding portion 6b.
In the present embodiment, the winding height HC from 5 is 0.3 times or more and 1.2 times the tread edge height HE, which is the radial distance from the bead bottom surface 15 of the tread edge E to the tread edge E. It is as follows.

In this embodiment, the belt layer 7 is composed of a belt ply 7a formed by spirally winding a narrow and long strip-shaped ply 10. As shown in FIG. 2, the belt-shaped ply 10 has one belt cord 11 or two belt cords 11, 11 arranged in parallel, as shown in FIG.
2, the belt cord 11 is made of an aromatic polyamide organic fiber cord.

The belt-shaped ply 10 extends from the starting point H1 which is the outer edge F of the belt layer 7 located near one end edge E of the tread portion 2 from left to right in FIG. 1 and at the tire equator C.
The belt ply 7 is spirally wound at a small angle of 5 ° or less with respect to the tire equator C until reaching the end point H2 that forms the outer edge F of the belt layer 7 in the vicinity of the other end edge E.
a can be formed. In addition, in this embodiment, when the strip-shaped ply 10 is wound, as shown in FIG. 4, the vicinity of the opposite side edges 10a and 10a of the strip-shaped ply 10 are wrapped around each other and wound to prevent the strip-shaped ply 10 from loosening. ing. The belt layer 7 includes two or more belt plies according to the above configuration,
That is, the spiral ply 10 may be formed as a plurality of layers by winding two or more layers.

The belt width WB, which is the distance between the outer edges F of the belt layer 7 in the tire axial direction, is 0.5 times the tread width WT, which is the distance between the edges E of the tread portion 2. The range is not less than 1.1 times and preferably not more than 1.1 times.

The belt cord 11 is formed by twisting filaments of the aromatic polyamide fiber and having a fineness of 840d.
A plurality of strands 13 of 1890d, preferably 2
The number of strands is 6 or more and 6 or less. Further, the twist number of the twisting is set to 29 times or less per 10 cm, preferably in the range of 24 to 29 times, so that the twist is formed. 3A shows a 4-strand belt cord 11 and FIG. 3B shows a 6-strand belt cord 1.
1 is shown respectively.

The belt cord 11 is formed into a flat cross section with the longitudinal axis X in the tire axial direction when twisted. When forming the flat shape, as shown in FIGS. 3 (A) and 3 (B), the pitch between the strands 13 is set to the longitudinal axis X.
It is formed by making it large in the direction and small in the short axis Y direction perpendicular to the long axis X.

The value of the ratio Y / X of the short axis Y to the long axis X is preferably in the range of 0.5 to 0.8. Further, by increasing the pitch in the direction of the longitudinal axis X in this manner, a gap g is created between the strands 13 and 13, the rubber easily penetrates into the gap g during topping of the cord, and strong topping can be achieved.

Such a belt ply 7a is formed, for example, by the steps described below. Strip ply 1 as described above on the profile drum
0 is spirally wound with the longitudinal axis of the belt cord 11 aligned with the surface direction of the drum. This spirally wound strip-shaped ply 10 is moved onto the carcass, and a rubber member such as tread rubber is attached to form a green tire. A green tire is loaded into a vulcanization mold and vulcanized and molded. The uneven pattern formed on the tread surface is formed by pressing and deforming the raw tire against the vulcanization mold during vulcanization.

As described above, the belt ply 7a moves a lot during the vulcanization process, and conventionally, during this movement,
Although the band-shaped ply 10 tends to be disturbed, since the belt cord 11 is spirally wound on the profile drum with the tire axial direction as the longitudinal axis, the wrap width of the side edges 10a and 10a of the band-shaped ply 10 is widened. As a result, it is possible to form a highly accurate and uniform belt ply without the cord being disturbed in the working process.

As a result, the lateral rigidity of the tire is improved,
When turning with a bank angle, the camber thrust is increased and the turning performance is improved.

The belt width WB which is the distance between the outer edges F of the belt layer 7 in the tire axial direction is 0.7 times the tread width WT which is the distance between the edges E of the tread portion 2. It is above and 1.0 times or less.

In the tread portion 2, a reinforcing layer made of a cross belt may be interposed between the carcass 6 and the belt layer or outside the belt layer 7 in the radial direction. This reinforcing layer is composed of one or more reinforcing plies in which a reinforcing cord made of an organic fiber cord is tilted at an angle of 10 to 30 ° with respect to the tire equator similarly to the carcass cord, and is composed of two or more reinforcing plies. Are arranged such that the reinforcing cords of each ply cross each other. The reinforcing layer thus formed is
Cooperate with the carcass and the belt layer to enhance the hoop effect and efficiently reinforce the tread portion, if necessary.

The belt ply 7a may be a cut ply composed of a sheet body in which belt cords are arranged in parallel, as long as the belt cords are made of aromatic polyamide fibers and have the regulated twist. Can be modified in various ways.

[0038]

SPECIFIC EXAMPLE A tire having a tire size of 170/60 VR17 and having the configuration shown in FIG. 1 is experimentally manufactured with the specifications shown in Table 1 and the rubber composition shown in Table 2 (Example 1
~ 4) and tested its performance. For comparison, tires having conventional structures (Comparative Examples 1 to 6) were also tested and their performances were compared.

The test conditions are as follows. A) Drum test Using each of the example tires and comparative example tires, the high speed durability, the camber thrust and the generation speed of the standing wave were investigated using an indoor drum tester. The high-speed durability and the chamber thrust are indicated by an index with Comparative Example 1 being 100. The larger the value, the better.

B) Actual vehicle test Each test tire was mounted on the rear wheel of the motorcycle, and
On a test road, the vehicle was run on a straight road and a curved road at a speed of 250 to 280 km / H, and the ride comfort including vibration generation speed, high-speed straight-run stability, high-speed turning stability, and tire uniformity was investigated. The high-speed straight running stability, the high-speed turning stability, and the riding comfort were evaluated based on the driver's feeling, and displayed as an index with Comparative Example 1 as 100. The larger the value, the better.

C) Workability When the belt-shaped ply having the belt cord covered with the topping rubber is spirally wound around the profile drum, the winding speed is set to 100 at the winding speed of the belt-shaped ply of the conventional structure (Comparative Example 1). Displayed as an index. The higher the value, the higher the workability. The test results are shown in Table 1.

[0042]

[Table 1]

[0043]

[Table 2]

As a result of the test, it was found that the tires of Examples had better running performance and workability and the tire uniformity was improved as compared with the tires of Comparative Examples.

[0045]

As described above, in the motorcycle tire of the present invention, the belt cord is formed of the aromatic polyamide fiber, and further, it is formed by the low twist cord in which the fineness and the number of twists of the strand are regulated. Therefore, the uniformity of the tread portion can be improved, the straight traveling stability and the turning traveling stability and the durability can be improved during safe traveling, and the workability can be improved and the economical production can be achieved.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a belt-shaped ply forming a belt layer.

3A and 3B are cross-sectional views illustrating the filament configuration of the belt cord.

FIG. 4 is a cross-sectional view illustrating the winding of a strip-shaped ply.

FIG. 5 is a graph showing a load elongation curve of a belt cord.

[Explanation of symbols]

 2 tread portion 3 sidewall portion 4 bead portion 5 bead core 6 carcass 7 belt layer 7a belt ply 10 belt-shaped ply 11 belt cord 12 topping rubber E edge WB belt layer tire axial width WT tread width X longitudinal axis

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[Procedure amendment]

[Submission date] April 30, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

[0038]

[Specific example] Tire size is 170/60 A tire having R17 and having the configuration shown in FIG. 1 is experimentally manufactured with the specifications shown in Table 1 and the rubber composition shown in Table 2 (Example 1
~ 4) and tested its performance. For comparison, tires having conventional structures (Comparative Examples 1 to 6) were also tested and their performances were compared.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

The test conditions are as follows. A) Drum Test Using a drum tester having a diameter of 60 inches, the high-speed durability, the camber thrust, and the standing wave generation rate were investigated for each of the example tires and the comparative example tires. High-speed durability and chamber thrust are Comparative Example 1
Is shown as an index. The larger the value, the better. (1) Internal pressure of 2.25 kg / cm ² and a load of 150% of the maximum load of JIS standard were applied to each test tire, and the peripheral speed was 65 km / H.
While traveling, the total running distance until cracks were generated on the tire surface was measured. (2) Camber thrust A maximum internal pressure specified by JIS and a load of 40% of the specified maximum load was applied to each test tire, and the drum was rotated at a peripheral speed of 30 km / H to measure the camber thrust. (3) Standing wave generation speed Each standing tire started with an initial speed of 230 km / H under a load of 229 kg and an internal pressure of 2.25 kg / cm ² , and the speed was increased by 10 km / H every 10 minutes to generate a standing wave. It was judged by the speed at which.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

B) Actual Vehicle Test (1) Natural Vibration Generation Speed Each sample tire was mounted on the rear wheel of the motorcycle and traveled on a highway, and the natural vibration speed was determined by the driver's feeling. (2) Each test tire is mounted on the rear wheel of the motorcycle, and the test road is driven at a speed of 250 to 280 km / H on straight roads and curved roads respectively, and vibration generation speed, high-speed straight-running stability, and high-speed turning stability Riding comfort including tire quality and tire uniformity was investigated. The high-speed straight running stability, the high-speed turning stability, and the riding comfort were evaluated based on the driver's feeling, and the comparative example 1 was expressed as an index of 100. The larger the value, the better. In the actual vehicle test, the tire size of the front wheels was 120/7.
A tire with a conventional specification of 0 R17 was attached.

Claims (3)

[Claims] 1. A toroidal carcass in which a tread width, which is a distance in the tire axial direction between end edges of the tread portion, has a maximum tire width, and which is folded back around a bead core of a bead portion through a sidewall portion from a tread portion. , Inside the tread portion and outside in the radial direction of the carcass, and the width in the tire axial direction is 0.5 times or more the width of the tread and 1.1.
A motorcycle tire having a belt layer of not more than double, wherein the carcass is formed by a carcass ply of a radial arrangement in which a carcass cord made of an organic fiber is inclined at an angle of 70 to 90 ° with respect to the tire equator. On the other hand, the belt layer is formed by a belt ply in which belt cords are arranged in parallel, and the belt cord is formed by twisting a plurality of strands of 840 to 1890d in which filaments made of aromatic polyamide fiber are twisted together, and per 10 cm. A tire for a motorcycle, characterized in that it is a low-twist having a twist number of 29 or less and twisted together, and is composed of a cord having a flat cross-sectional shape with the tire axial direction as a longitudinal axis. 2. The belt ply is arranged in parallel by spirally winding a narrow and long strip-shaped ply in which the cord of the low twist is covered with a topping rubber at a small angle with respect to the tire equator. The motorcycle tire according to claim 1, wherein the tire is a motorcycle tire. 3. The tire for a motorcycle according to claim 1, wherein the belt cord has a flat cross-section with an oblateness of 0.5 or more and 0.8 or less.