JPH10278519A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain and improve the various characteristic of tire, and while to reduce the weight thereof by winding and heaping a rubber coated cord in the circumferential direction of a tire so that a bead core and a filler are integrally formed with each other. SOLUTION: A bead core-filler structure, which is obtained by integrally forming a bead core and a bead filler with each other, is arranged in a bead part 12. The bead filler structure 24 is a complex obtained by embedding a cord 26, which is arranged in the circumferential direction of a tire, in the hard rubber, and formed by winding a cord-like material 30, which is formed by coating the cord 26 with rubber, in the circumferential direction of the tire and heaping so as to be tapered outside in the radial direction. With this structure, the bead core-filler body 24, in which the cord 26 is arranged over the whole thereof, is sufficiently reinforced. Lowering of volume is thereby enabled, and a bead reinforcing layer is unnecessary. As a result, while various characteristic of tire is maintained and improved, lowering of volume and reduction of weight of the bead part 12 are realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a pneumatic radial tire.

[0002]

2. Description of the Related Art A pneumatic radial tire is usually provided with a carcass running in a tire radial direction and a belt running in a tire circumferential direction. Further, as a main rigid reinforcing material in a bead portion of the tire, an outer peripheral side of a bead core is used. Is provided with a hard rubber bead filler.

For example, as shown in FIG. 6, a bead portion 100 of a conventional tire includes a bead core 101 for locking both side ends 20a of a carcass 20, and a bead filler 102 disposed on the outer peripheral side thereof. The bead core 101 is made of a steel wire, a steel plate, or an organic fiber wound in an annular shape, and the bead filler 102 is made of a hard rubber having a substantially triangular cross section.

In recent years, as the performance of tires has been improved, a bead reinforcing layer 103 made of a steel cord or the like has been provided on the outer surface of the bead filler 102.

[0005]

By the way, resource saving has come to be said from various fields, and the demand for tires to reduce the amount of material used and to reduce rolling resistance (to improve fuel efficiency) by reducing the thickness and weight has increased. I have.

However, in the above-mentioned conventional structure, the rigidity of the tire bead portion is limited to the carcass 20, the bead core 101, the bead filler 102, and the bead reinforcing layer 103.
If the weight is reduced with the above-mentioned conventional structure and material, the rigidity of the tire bead portion becomes insufficient, and a problem arises in that the running performance of the tire is impaired. That is, it is difficult to reduce the weight while maintaining the various characteristics of the tire with the conventional structure and material.

In the case of the above conventional structure, the bead core 101, the bead filler 102, and the bead reinforcing layer 103
Are prepared in separate facilities and processes, respectively, and are combined at the time of molding a green tire, so there is room for improvement in terms of facilities and production man-hours.

Accordingly, an object of the present invention is to provide a pneumatic radial tire capable of reducing the weight while maintaining and improving the kinetic performance of the tire by means described below.

[0009]

According to a first aspect of the present invention, there is provided a pneumatic radial tire according to the present invention, wherein a bead core for locking both ends of a carcass and a bead filler on an outer peripheral side thereof are formed by rubber-coated cords in the tire circumferential direction. Bead core that is stacked in a shape that tapers outward in the tire radial direction while being wound around
It is characterized by being integrally formed as a filler body.

[0010] As described above, the bead core and the bead filler are integrally formed as a bead core-filler body by winding up the rubber-coated cord while winding the cord in the tire circumferential direction. Is sufficiently reinforced by cords having a modulus sufficiently higher than the hard rubber disposed throughout. As a result, the volume of the bead filler can be reduced, and a bead reinforcing layer is not required.Thus, while maintaining and improving various tire characteristics, it is possible to achieve low volume and light weight of the bead portion, The weight of the tire can be reduced. In addition, bead core-
Since the filler body is formed, the productivity is superior and the cost can be reduced as compared with the conventional case where a plurality of members are combined.

According to a second aspect of the present invention, in the tire according to the first aspect, the rubber-coated cords constituting the bead core-filler body are composed of a plurality of cords having different stiffness, and the stiffness increases inward in the radial direction. A high code is provided. Thereby, it is possible to easily make a good rigidity balance of the tire from the bead portion to the side portion while maintaining the rigidity of the bead portion high.

Here, the bead core-filler body is formed of a radially inner high rigid portion and a radial outer low rigid portion, and an interface between the high rigid portion and the low rigid portion is formed on the bead base surface. On the other hand, by inclining radially outward from the inner side to the outer side in the tire width direction (Claim 3), the rigidity in the outer side in the tire width direction is increased, and when a lateral force is applied to the tire, the lateral force applied to the tire is reduced Can withstand enough force. as a result,
Steering response characteristics are improved, and steering stability can be improved.

Conversely, the interface between the high-rigidity portion and the low-rigidity portion is inclined radially inward from the inside in the tire width direction to the outside with respect to the bead base surface.
The rigidity on the outer side in the tire width direction is reduced, and the tire is easily distorted. As a result, the generated noise can be reduced by absorbing the impact force during traveling.

As described above, by changing the slope of the interface, the optimum balance can be more easily made in accordance with the application and required performance of the tire.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic radial tire according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the right half of a radial tire 10 according to the first embodiment. In the figure, 12
Is a bead part, 14 is a side part, 16 is a shoulder part, 1
Reference numeral 8 denotes a tread portion, reference numeral 20 denotes a carcass, reference numeral 22 denotes a belt, and the tire 10 includes a pair of right and left bead portions 12, a side portion 14, a shoulder portion 16, and a tread portion 18 extending between the shoulder portions 16. The carcass 20
It consists of one or more carcass plies in which fibers or steel cords are arranged at an angle of about 90 ° with respect to the center (equator) in the tire width direction. 16 and the side portions 14, the end portions 20 a at the left and right bead portions 12.
Is wound up and locked. In the drawings, R indicates a rim on which the bead portion 12 of the tire 10 is arranged.

The bead portion 12 is provided with a bead core-filler body 24 formed integrally with a bead core and a bead filler. Here, the term “integrally” means that the rubber coated with both the bead core and the bead filler is wound in the tire circumferential direction, instead of being formed by winding a rubber-coated cord with only the bead core as in the related art. Means that it is formed by
The codes need not necessarily be continuous. The bead core-filler body 24 is an annular member having a substantially triangular cross section, and the end 20a of the carcass 20 is wound therearound from the inside toward the outside.

The bead core-filler body 24 is a composite in which a cord 26 running in the tire circumferential direction is embedded in a hard rubber, and as shown in FIG.
8 is formed by winding a single cord-like material 30 covered with 8 and winding up in the tire circumferential direction so as to taper outward in the radial direction. In this way, by stacking in the outwardly tapered shape, the number of the cords 26 arranged at the upper end portion of the bead core-filler body 24, that is, at a portion radially outward, is reduced, and A desired rigidity distribution is obtained in a portion reaching 14.

The cord 30 is usually made of a single cord 26 covered with a rubber 28. In some cases, a plurality of cords 26 covered with a rubber 28 is used. May be used.

As the cord 26, an organic fiber such as nylon, polyester, vinylon, rayon, and aramid, or a composite cord in which metal fibers such as steel are singly or twisted can be used.

When manufacturing a tire having such a bead core-filler body 24, the bead core-filler body 24 is formed by winding and stacking a string 30 in advance, and the bead core-filler body 24 is formed into a carcass 20 at the time of tire molding. Alternatively, the bead core-filler body 24 may be formed by assembling with other tire constituent members, or by winding and stacking the cord-like material 30 directly on both ends of the carcass 20 at the time of forming the tire.

As described above, since the bead core and the bead filler are integrally formed by winding and stacking the cords 26, the integrally formed bead core-filler body 24 is formed as a whole. Code 26 over
Are provided, and are sufficiently reinforced by the cord 26.
Therefore, it is possible to reduce the volume in a portion corresponding to the conventional bead filler, and the bead reinforcing layer is not required. As a result, the volume and weight of the bead portion 12 can be reduced while maintaining and improving various tire characteristics. Further, in order to form the bead core-filler body 24 by winding and stacking the cord 26,
It is easy to change the width, and it is superior in productivity as compared with a conventional combination of a plurality of members.

FIG. 3 shows a structure of a bead portion 12 in a pneumatic radial tire according to a second embodiment of the present invention.

In this embodiment, the bead core-filler body 24 of the first embodiment is provided with a radially inward high rigidity portion 2.
4a and a low-rigidity portion 24b radially outward. That is, the bead core-filler body 24 is
The rubber-coated cords 26a and 26b having different rigidities are
The cord 26a having higher rigidity toward the inside in the radial direction and the cord 26b having lower rigidity toward the outside are wound and stacked to be integrally formed. Specifically, first, the high rigidity portion 24a is formed by winding and stacking the high rigidity cord 26a, and then, the low rigidity portion 2 is formed by winding and stacking the low rigidity cord 26b outside thereof.
4b is formed.

FIG. 3B shows an example of a winding / stacking structure of the cords 26a and 26b. In this example,
First, as shown by the arrow, the high rigid cord 26a wound in the circumferential direction is piled up at both ends in the width direction of the bead core-filler body 24 to form a high rigid portion 24a,
Then, the low rigidity cord 26b wound in the circumferential direction is
As indicated by the arrow, the bead core-filler body 24
To form a low-rigidity portion 24b.

The plural kinds of cords 2 having different rigidities as described above
When using No. 6, it is preferable to use a steel cord or an aramid cord for the high rigidity portion 24a and to use a nylon cord, polyester cord, vinylon cord or rayon cord for the low rigidity portion 24b. However, high rigidity part 2
When a steel cord is used for 4a, the low rigidity portion 24
It is also preferable to use an aramid code for b.

In this embodiment, the interface 32 between the high-rigidity portion 24a and the low-rigidity portion 24b is inclined radially outward with respect to the bead base surface 12a from the inside to the outside in the tire width direction. In addition, the bead base surface 12a is the bottom surface of the bead portion 12 arranged in contact with the rim base,
In the present embodiment, they are arranged slightly inclined with respect to a horizontal plane including the tire rotation axis.

In order to enhance the rigidity effect of the bead portion 12, the high rigid portion 24a has a height H (a maximum dimension in a direction perpendicular to the bead base surface 12a) whose width H (a surface parallel to the bead base surface 12a). The maximum width in W)
It is configured to be 1.2 times or more. In this embodiment, since the upper end of the high-rigidity portion 24a is the outer end of the interface 32, the height Ho of the outer end is 1.2 times or more of W.

In the tire of this embodiment, the bead core
Since the filler body 24 includes the radially inner high rigidity portion 24a and the radially outward low rigidity portion 24b, the bead portion 12
While maintaining high rigidity, the rigidity balance from the bead portion 12 to the side portion 14 is excellent. The interface 32
Is inclined radially outward toward the width direction with respect to the bead base surface 12a, so that the outer rigidity of the bead portion 12 is high and the steering stability is high as described later.

FIG. 4 shows an interface 32 according to the second embodiment.
2 shows another configuration example. In this example, the interface 32 is
It is inclined radially inward from the inside in the tire width direction to the outside with respect to the bead base surface 12a. Again, in this case,
As shown in FIG. 4B, first, the cord 26a having high rigidity is used.
Subsequently, as shown by arrows, the low rigidity cords 24b and the low rigidity parts 24b can be formed by stacking the cords 26b with low rigidity at both ends in the width direction of the bead core-filler body 24. it can.

As described above, the interface 32 is formed on the bead base surface 12.
By inclining radially inward toward the width direction outward with respect to a, the outer rigidity of the bead portion 12 is low and the tire is easily bent, so that the road noise performance is high as described later.

In this case, the height H of the high rigidity portion 24a is
Is the height Hi of the inner end of the interface 32, and the height Hi of the inner end is 1.2 times or more the width W of the high-rigidity portion 24a. The interface 32 may be flat as in the example shown in FIG. 3 or may be curved as in this example.

FIG. 5 shows an interface 32 according to the second embodiment.
3 shows still another configuration example. In this example, the interface 32
Has a chevron shape protruding radially outward. That is, the high-rigidity portion 24a has a mountain-like shape, and the height H of the top is high.
It is 1.2 times or more the width W of 4a.

In this case, the winding of the cords 26a and 26b
FIG. 5B shows an example of the stacking configuration. In this example, the low-rigidity portion 24b is wound separately into two regions I and II. That is, first, a highly rigid cord 2 wound in the circumferential direction.
6a are stacked so as to be folded at both ends of the chevron forming the interface 32 to form the high rigidity portion 24a. Subsequently, the first regions I are formed by sequentially winding the cords 26b having low rigidity on the outer side in the width direction of the high rigidity portion 24a to form the first region I. Further, the rigidity is low on the inner side in the width direction of the high rigidity portion 24a. The second region II is formed by winding the cords 26b so as to be sequentially stacked, thereby forming the low rigidity portion 24b.

[0035]

EXAMPLES In order to confirm the above-mentioned effects, the following examples were performed with a tire size of 205 / 55R16.

[0036] was created each tire of Examples 1 to 4 and Comparative Example 1 by the bead member configuration shown in Examples 1 to 4 and Comparative Example 1 in Table 1. Details are as follows.

Embodiment 1: The structure shown in FIG. As the cord 26, a 3,000-denier aramid four-strand cord is used, and a cord-like object 30 having a cross-sectional area of 2.0 mm ² and a width W = 8.0 mm and a height (bead base surface 1)
(Maximum dimension in the direction perpendicular to 2a) Ht = 60 mm.

Embodiment 2: The structure shown in FIG. Bead core
The width W of the filler body 24 is 8.0 mm, and the height Ht is 60 m.
m. In the high-rigidity portion 24a, the cord 30 similar to that of the first embodiment was wound and stacked so that the height Ho at the outer end of the interface 32 was 25 mm and the height Hi at the inner end of the interface 32 was 7.0 mm. In the low rigidity portion 24b, 126
Using a two-strand cord of 0 denier nylon 6,6,
This is a rubber-coated material 3 having a cross-sectional area of 1.1 mm ^2.
0 was wound and stacked.

Embodiment 3: The structure shown in FIG. Bead core
The width W of the filler body 24 is 7.0 mm and the height Ht is 60 m
m. The high-rigidity section 24a, using a steel cord having a diameter of 0.96mm as code 26a, which the cord-like material 30 of the cross-sectional area 1.5 mm ² formed by rubber-coated, height Ho = 15 mm of the outer end of the interface, Winding and stacking were performed so that the height Hi of the inner end of the interface 32 was 2.6 mm. Low rigidity part 24b
In using the 2-ply cords of 1500 denier aramid as code 26b, which was wound, stacked string-like material 30 of the cross-sectional area 1.1 mm ² formed by a rubber coating.

Embodiment 4: The structure shown in FIG. Bead core
The width W of the filler body 24 is 7.0 mm and the height Ht is 60 m
m. In the high-rigidity portion 24a, the high-rigidity portion 2 of the third embodiment is used.
A string 30 similar to that of FIG.
It was wound and stacked to a height of 2.6 mm and a height Hi = 15 mm at the inner end of the interface 32. In the low-rigidity portion 24b, the string 30 similar to the low-rigidity portion 24b of the third embodiment was used for winding and stacking.

Comparative Example 1: The structure shown in FIG. Bead core 1
No. 01 is a ring-shaped bundle in which a total of 25 steel wires each having a diameter of 0.96 mm, five, five, five, five, and five, are arranged from the radial inside, and a width w = 7.0 mm. , Height h1
= 7.0 mm. As the bead filler 102,
Using a substantially triangular rubber member, height h2 = 45 mm
And 2 + 2 × 0.2 as the bead reinforcing layer 103
Height h3 = 5 using a member made of steel cord No. 2
3 mm.

With respect to the tires of Examples 1 to 4 and Comparative Example 1, tire stiffness (lateral stiffness, front-back stiffness), cornering power, rolling resistance, steering stability and road noise performance were measured. Table 1 shows the results. In Table 1, all of these physical properties are represented by indices when the value of the tire of Comparative Example 1 is set to 100. Only the rolling resistance is smaller when the index is smaller, and other performances indicate that the larger the index is better.

[0043]

[Table 1] The measuring method of each physical property is as follows.

Tire rigidity: The lateral rigidity ky is measured by applying a lateral force corresponding to 30% of the reference load to a tire to which a reference load is applied in the vertical direction by a compression tester, and measuring the lateral deflection. Calculated by dividing the lateral force by the amount of lateral deflection. The longitudinal rigidity kx is calculated by applying a longitudinal force equivalent to 30% of the reference load to the tire to which the reference load is applied, measuring the longitudinal flexure, and dividing the longitudinal force by the longitudinal flexure amount. .

Cornering power: A drum test is performed at a slip angle of 2 °, and the laterally generated force is divided by 2 to calculate the cornering power.

Rolling resistance; reference internal pressure, reference load, speed 8
Run on a drum at 0 km / h and measure rotational resistance.

Road noise performance; air pressure 2.0 kgf /
a tire was cm ² is attached to the domestic passenger car of 3000cc class, speed 60km / h in a state that was allowed to ride the 2 people
The car was driven on rough pavement roads to evaluate the sound inside the car.

Driving stability: The driver evaluated the feeling of the test vehicle on a test course by a predetermined running method.

As shown in Table 1, the tires of Examples 1 to 4 maintain and improve the tire rigidity, cornering power and rolling resistance while reducing the weight of the bead portion as compared with the tire of Comparative Example 1. I was When compared with the same material, the interface 32 between the radially inner high rigidity portion 24a and the radially outer low rigidity portion 24b of the bead core-filler body 24 is obtained.
However, in the tire of Example 3 in which the tire is inclined radially outward from the inside in the tire width direction to the outside with respect to the bead base surface 12a, Example 4 in which the interface 32 is inclined inward in the radial direction. The tires of Example 4 were superior in steering stability, and conversely, Example 4 was more excellent in road noise performance than Example 3.

[0050]

According to the pneumatic radial tire of the present invention, various characteristics of the tire can be obtained by winding and stacking a rubber-coated cord in the tire circumferential direction to integrally form a bead core and a bead filler. Weight can be reduced while maintaining and improving.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a right half of a pneumatic radial tire according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional perspective view of a main part of the radial tire, showing a state in which a rubber-coated cord is stacked while being wound.

FIG. 3A is a cross-sectional view of a bead portion of a pneumatic radial tire according to a second embodiment, and FIG. 3B is a schematic cross-sectional view showing an example of forming a bead core-filler body of the bead portion. FIG.

FIG. 4A is a cross-sectional view illustrating another configuration example of a bead portion in the second embodiment, and FIG. 4B is a schematic cross-sectional view illustrating an example of forming a bead core-filler body of the bead portion. FIG.

FIG. 5A is a cross-sectional view illustrating still another configuration example of a bead portion according to the second embodiment, and FIG. 5B is a cross-sectional view illustrating an example of forming a bead core-filler body of the bead portion. It is a schematic diagram.

FIG. 6 is a sectional view of a bead portion of a conventional pneumatic radial tire.

[Explanation of symbols]

 10 ... pneumatic radial tire 12 ... bead part 20 ... carcass 24 ... bead core-filler body 24a ... high rigidity part 24b ... low rigidity part 26 ... cord 26a ... cord constituting high rigidity part 28b ... low rigidity Cords constituting part 28 Rubber 30 String 32 Interface

Claims (4)

[Claims] 1. A bead core for locking both side ends of a carcass and a bead filler on an outer peripheral side of the bead are piled up in a shape that tapers outward in a tire radial direction while winding a rubber-coated cord in a tire circumferential direction. A pneumatic radial tire formed integrally as a bead core-filler body. 2. The rubber-coated cord constituting the bead core-filler body is composed of a plurality of cords having different rigidities, and the cords having a higher rigidity are arranged radially inward. Item 4. The pneumatic radial tire according to item 1. 3. The bead core-filler body comprises a radially inward high rigidity portion and a radially outward low rigidity portion, the interface of which extends from the tire width direction inner side to the outer side with respect to the bead base surface. 3. The pneumatic radial tire according to claim 2, wherein the pneumatic radial tire is inclined radially outward. 4. The bead core-filler body comprises a radially inward high rigidity portion and a radially outward low rigidity portion, the interface of which extends from the tire width direction inside to the outside with respect to the bead base surface. The pneumatic radial tire according to claim 2, wherein the tire is inclined inward in the radial direction.