JPH0891013A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To provide a pneumatic radial tire which wan improve the high speed durability and the steering stability. CONSTITUTION: As for a pneumatic radial tire 10 in which at least two belt layers 22 consisting of belts 24 and 26 between a tread 12 and a carcass 20, a belt reinforcing member 32 which bends both the end parts of the belt layer 22 at the end of the belt layer 22 and enfolds them is arranged, and the belt reinforcing member 32 is formed of the cords 34 which incline for the tire circumferential direction, and the cord 34 of the belt reinforcing member 32 crosses, in the reverse inclination direction for the tire circumferential direction, with the cords 28 and 30 which constitute the contiguous belts 24 and 26.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a pneumatic radial tire.

[0002]

2. Description of the Related Art Conventionally, in a pneumatic radial tire, particularly a radial tire for passengers, in order to improve high-speed durability, it is necessary to add a belt auxiliary layer to a belt arranged between a tread and a carcass layer. (Japanese Patent Publication No. 57-61601).

For example, as shown in FIG. 9, in a conventional tire 100, a belt layer 103 surrounding the carcass layer 102 in the tire circumferential direction is arranged between a tread 101 and a carcass layer 102, and the belt layer On the top of 103
An edge ply and a cap ply 104 made of an organic fiber cord such as nylon are added as a belt auxiliary layer.

The belt layer 103 is composed of the upper and lower two belts 10.
3a, 103b, the upper belt 1
The steel cord constituting 03a has an angle θ = 10 ° to 35 ° with respect to the tire circumferential direction, and the steel cord constituting the lower belt 103b has an angle θ = −10 ° to −35 ° with respect to the tire circumferential direction. It is distributed and has.
As a result, both steel cords intersect each other.
The angle θ of the belts 103a and 103b with respect to the tire circumferential direction may be reversed depending on how the belts are attached. Here, the angle θ is an angle with respect to one direction in the tire circumferential direction, and in FIG. 3, the one tilted to the right is positive, and the one tilted to the left is negative (hereinafter, similarly used. Yes.).

The edge ply and cap ply 104 are
Edge plies 104a surrounding both ends of the belt layer 103
And a cap ply 104b surrounding the entire surface of the belt layer 103 on the outer side of the ply 104a.
The cords forming 104b make an angle of approximately 0 ° with the tire circumferential direction.

By the auxiliary layer 104, the tread 10
Since the rigidity of the shoulder portion 105, which is the both end portions of No. 1, is increased, the shoulder portion 105 is prevented from rising during high-speed traveling, and high-speed durability is improved.

[0007]

However, in the conventional tire 100, at the time of vulcanization molding, the number of ends, which is the number of cords driven per inch in the belt width direction, decreases at both ends of the belt layer 103, and the density thereof is reduced. Becomes sparse.
That is, the cords at both end portions of the belt layer 103 have sidewall portions 106 that are continuous from the tread shoulder portion 105,
It spreads in the direction of 106. This is because the restraint due to the intersection of the steel cords of the two belts 103a and 103b is weak at the end portion of the belt layer 103.

[0008] The belt auxiliary layer 104 does not contribute to the maintenance of the end number at all, so that the belt rigidity is lowered,
In addition, it becomes non-uniform and the driving stability cannot be improved. This is because the steering stability is greatly affected by the end number distribution at the belt end.

In view of the above points, an object of the present invention is to provide a pneumatic radial tire having improved both high speed durability and steering stability.

[0010]

A pneumatic radial tire according to claim 1 of the present invention is a pneumatic radial tire in which a belt layer composed of at least two belts is arranged between a tread and a carcass. A belt reinforcing material that folds and encloses both ends of the layer at the belt layer end is arranged, and the belt reinforcing material is formed by a cord inclined with respect to the tire circumferential direction, and the cord of the belt reinforcing material is The cords forming the adjacent belts intersect with each other in the direction of inclination opposite to the tire circumferential direction.

A pneumatic radial tire according to a second aspect of the present invention is the pneumatic radial tire according to the first aspect, wherein the cord forming the belt reinforcing material is made of an organic fiber such as nylon, rayon or polyester.

A pneumatic radial tire according to a third aspect is the pneumatic radial tire according to the first or second aspect, wherein the belt reinforcement is
It is formed of two reinforcing materials that respectively wrap around the respective end portions of the belt layer.

[0013]

According to the pneumatic radial tire of claim 1,
Both ends of the belt layer are wrapped by the belt reinforcing material, and the cords of the belt reinforcing material intersect the cords of the adjacent belts in the direction of inclination opposite to the tire circumferential direction. Therefore, at the time of vulcanization molding, the belt reinforcing material sufficiently wraps the belt layer, so that the number of ends at the end portion of the belt layer does not decrease and the number of ends can be maintained in a dense state before vulcanization molding. it can.

Further, in the tire according to the second aspect, since the cord of the belt reinforcing material is made of organic fiber such as nylon, rayon, polyester, etc., it is arranged at both ends of the belt so as to be doubled up and down. The belt reinforcement does not increase the rigidity of both ends of the belt too much.

Further, in the tire of claim 3, since the belt reinforcing material is formed by two reinforcing materials which respectively wrap each end portion of the belt layer, the reinforcing material is provided only at both end portions of the belt layer. can do.

[0016]

EXAMPLES A radial tire 10 according to an example of the present invention will be described below with reference to FIGS.

Reference numeral 12 is a tread of the tire 10, and the tread 12 has four linear grooves 14 continuous in the tire circumferential direction. The four grooves 14 form a center rib 12a located at the center of the tread 12, shoulder ribs 12c and 12c located at both ends of the tread 12, and a center rib 12a and shoulder ribs 12c and 12c. Five ribs, which are the 1/4 point ribs 12b and 12b located between them, are separated. In addition, CL is a tire center line which shows the tread crown center of the tire 10.

Reference numeral 16 is a pair of sidewall portions which are continuous with both shoulder ribs 12c, 12c of the tread 12 and extend inward in the radial direction of the tire 10. A ring-shaped bead wire 18 is arranged on the inner circumference of each sidewall portion 16, and the both sides 18 and 18 form a pair.

Reference numeral 20 is a carcass layer in which cords are arranged in the radial direction of the tire 10. This carcass layer 2
No. 0 has its both ends wound around the bead wire 18, and is formed of a one-layer or two-layer ply made of polyester cords or organic fiber cords such as rayon fibers arranged at about 90 ° with respect to the tire circumferential direction. Has been done.

Reference numeral 22 indicates the tread 12 and the carcass layer 2
It is a belt layer which is disposed between the carcass layers 20 and 0. The belt layer 22 is on the lower side, that is, the carcass layer 2
It is formed by two belts, a first belt 24 on the 0 side and a second belt 26 on the upper side, that is, on the tread 12 side.

Each of the belts 24 and 26 has a structure in which a plurality of steel cords are embedded in rubber formed in an annular shape. The steel cord 28 of the first belt 24 has an angle θ = −1 with respect to the circumferential direction of the tire 10.
The second belt 26 is arranged at an angle of 0 ° to −35 °.
Steel cords 30 are arranged at an angle θ = 10 ° to 35 ° with respect to the tire 10 circumferential direction. The first
The angle θ between the belt 24 and the second belt 26 may be reversed depending on how to attach.

As described above, the steel cords 28 and 30 of the belts 24 and 26 are arranged so as to intersect each other with the inclination direction opposite to the tire circumferential direction.

Reference numeral 32 is a belt reinforcing material that wraps the belt layer 22 from the lower surface side. This belt reinforcement 32
Is a lower surface side of the first belt 24, that is, the main body 32a disposed between the carcass layer 20 and the first belt 24, and the main body 3
The bent portions 32b are bent from both ends of the second belt 26 to the upper surface of the second belt 26, and wrap around both ends of the two belts 24 and 26 over the entire tire circumferential direction.

The cord 3 constituting the belt reinforcing member 32
4 is made of nylon fiber and is arranged at an angle with respect to the tire 10 circumferential direction. The angle is, on the lower surface side of the first belt 24, that is, on the main body 32a,
Angle θ = 10 ° to 40 ° with respect to the tire circumferential direction, −10 ° at the upper surface side of the second belt 26, that is, at the bent portion 32b.
It is -40 degree. As a result, as shown in FIG. 3, between adjacent layers, that is, between the belt reinforcing material main body 32a and the first belt 24, between the first belt 24 and the second belt 26, and between the second belt 26 and the bent portion 32b. , Each code 34, 2
8 and 30 are configured to have an angle that alternates with the tire circumferential direction.

When the first belt 24 and the second belt 26 are attached in the opposite manner, the angles of the main body 32a and the bent portion 32b are also opposite.

In manufacturing the tire 10, in the molding step, the carcass 20 is wound around a flat drum, and sidewall portions and bead portions are formed at both ends thereof. Then, while holding the bead portion,
The carcass 20 is inflated to the product size by air pressure. On the other hand, the belt layer 22 is placed on the upper surface of the belt reinforcing material 32 formed in advance in the shape of a blind, and both end portions 32b of the reinforcing material 32 are
32b is bent on the upper surface of the belt layer 22, and the tread portion 12 is bonded to the upper surface of the belt layer 22.
Then, the belt layer 22 on which the tread portion 12 is arranged is pasted on the inflated carcass 20 and then vulcanized and molded to manufacture.

Next, a radial tire 40 according to another embodiment of the present invention will be described with reference to FIGS.

The tire 40 is different from the above-described tire 10 in the structure of the belt reinforcing material that wraps the belt layer 22.

The belt reinforcing member 42 of the tire 40 wraps the belt layer 22 from the upper surface side. That is, the belt reinforcing member 42 is provided on the upper surface side of the second belt 26, that is, between the tread 12 and the second belt 26.
And from both ends of the main body 42a to the lower surface side of the first belt layer 24,
That is, the bent portion 42b is bent between the carcass layer 20 and the first belt 24.

The cord 4 constituting the belt reinforcing member 42
4 is made of nylon fiber, and tire 40
It is arranged at an angle to the circumferential direction. In the main body 42a, the angle is the angle θ = with respect to the tire circumferential direction.
-10 ° to -40 °, θ = 10 ° to the bent portion 42b
It is 40 °. As a result, as shown in FIG. 6, the adjacent layers, that is, the belt reinforcing material main body 42a and the second belt 2 are
6, the second belt 26 and the first belt 24, the first belt 24
And the bent portions 42b between the cords 44, 28, 30
Have an angle that alternates with the tire circumferential direction. When the attaching directions of the first belt 24 and the second belt 26 are opposite, the main body 42a and the bent portion 42
The angle of b is also reversed.

In manufacturing the tire 40, a belt reinforcing member 42 formed in a blind shape is formed in the molding process.
On the upper surface of the belt layer 22. Then, the tread portion 12 is further attached to the upper surface thereof, while both end portions 42b, 42b of the belt reinforcing member 42 are bent to the lower surface side of the belt layer 22 and temporarily fixed. This is laminated on the carcass 20 which is inflated to near the product size. Then, it is vulcanized and molded.

As described above, when the end portions of the belt layer 22 are wrapped with the belt reinforcing members 32 and 42 like the tires 10 and 40,
The spread of the cord at the end portion of the belt layer 22 during vulcanization molding is suppressed, and the decrease in the number of ends at that portion is eliminated. Therefore, the rigidity of the end portion of the belt layer 22 is maintained, the belt rigidity as designed in the tire is maintained, and the rigidity balance can be improved. This improves steering stability. Further, the belt reinforcing members 32 and 42 prevent the shoulder portion 12c from rising, so that high-speed durability is improved.

Particularly, in the case of the belt reinforcing member 42 that wraps the belt layer 22 from the upper surface side, the bent portion 42b is sandwiched between the first belt 24 and the carcass layer 20 and restrained.
The nylon cord 44 has more tension. That is,
Since the restraining force for suppressing the spread of the end portion of the belt layer 22 becomes large, the number of ends becomes dense and the belt rigidity is improved, so that the steering stability is further improved.

The belt reinforcing members 32 and 42 are not limited to the nylon fiber cords 34 and 44 described above, and various types can be used. However, the tensile modulus of nylon, polyester, rayon, etc. is 1000 kg.
It is preferable to use organic fibers of f / mm ² or less.

When the tensile modulus is too large like the steel cord, the bent portion 32 that goes around only the tire end portion.
By b and 42b, the rigidity of the end portion of the tire becomes too strong, and the rigidity balance with the central portion deteriorates. Therefore, during high-speed traveling, the central portion of the tire rises, causing a peeling phenomenon between the cord and the rubber, resulting in low high-speed durability.

On the other hand, when the above-mentioned organic fiber is used as the cord, the cord can easily cope with the deformation of the tire during vulcanization molding, and the deformation can be allowed. Furthermore, nylon fiber cords are more preferable in terms of heat resistance and adhesiveness with rubber.

The folding margin of the belt reinforcing members 32 and 42, that is, the size of the bent portions 32b and 42b may be 10% or more of the half width of the first belt 24. If it is less than 10%,
The restraining force of the belt layer 22 is small and the wrapping effect is not sufficient. In addition, this bending allowance is in terms of wrapping effect,
70% is sufficient, and 40 to 50% is the best in consideration of workability, cost, tire weight and the like.

The cord 3 of the belt reinforcing members 32 and 42
The number of ends of 4, 44 is preferably 10 or more per inch.

The angle of the reinforcing cords 34 and 44 with respect to the tire circumferential direction is θ = 10 ° to 40 ° or
θ = −10 ° to −40 ° is desirable.

In the belt reinforcing members 32 and 42, the cords 34 and 44 are the cords 2 of the adjacent belts 24 and 26.
Since the belt layers 22 are arranged so as to intersect with the tire circumferential direction 8 and 30 in the direction opposite to the tire circumferential direction, the belt layer 22 is firmly held and its rigidity balance is maintained well.

Further, when the reinforcing cords 34, 44 have the above-mentioned angle with respect to the tire circumferential direction, the reinforcing members 32, 42 can be easily bent at the time of manufacturing.

The belt reinforcing members 32 and 42 do not need to be constructed such that the main bodies 32a and 42a cover the lower surface or the upper surface of the belt layer 22 over the entire width as described above. It may be composed of two reinforcing materials that respectively wrap each end so that only both ends of the layer 22 are wrapped.

The cords of the belt layer 22 are not limited to the steel cords 28 and 30 described above, but may be, for example, aromatic polyamide fiber cords or a combination cord of steel and aromatic polyamide fibers.
However, considering the tire rigidity, the tensile modulus is 10
It is necessary to use a material larger than 00 kgf / mm ² .

Further, the belt layer 22 includes two belts 2
The belt is not limited to the belt made of 4, 26 and may be made up of three or more belts. However, it is preferable to use an even number of sheets such as two sheets or four sheets because the cords can be alternately crossed between the belt reinforcing material and the belts and between all adjacent layers between the belts.

In order to confirm the above effects, the tire 10 according to one embodiment of the present invention (Example 1), the tire 40 according to another embodiment (Example 2), and the conventional edge ply and cap ply were reinforced. Tire 100 (Comparative Example 1), and
Various properties were evaluated for the unreinforced tire (Comparative Example 2).

In both Examples 1 and 2 and Comparative Examples 1 and 2, tires under the following conditions were used.

Tire size: 225/50 R169
2V, belt layer; the above-mentioned two-layer structure 24, 26, belt cord; steel cord having tensile modulus 18400 kgf / mm ² , steel cord constitution; 2 + 3 × 0.23 mm belt cord driving number; 18.9 / Inch, angle of cord 28 of first belt 24 with respect to tire circumferential direction; -23 °, angle of cord 30 of second belt 26 with respect to tire circumferential direction; 23 °.

Table 1 shows the reinforcing conditions for each tire.
Here, with regard to the reinforcing structure, "uphold" means
The structure in which both ends of the belt layer 22 are wrapped from the bottom to the top like the belt reinforcement 32, and the “down hold” is a structure in which both ends of the belt layer 22 are wrapped from the top to the bottom like the belt reinforcement 42. .

[0049]

[Table 1] FIG. 7 is a graph of the belt end number distribution of each tire. Here, the "measurement position" is defined as the half width of the belt layer being 100
Is shown by the distance from the belt center line CL. That is, the center line CL of the belt is 0, and the belt end is 100.
Is.

In both Examples 1 and 2, since the number of ends at the end portions of the belt did not decrease as in Comparative Examples 1 and 2, the belt rigidity was maintained at the end portions, and the belt rigidity in the tire width direction was maintained. Good balance. Therefore, the steering stability is improved.

Particularly, in the tire of Example 2, the number of ends at the belt ends is dense, and the belt rigidity at the ends is improved. Therefore, it is more preferable in terms of improving the steering stability.

FIG. 8 is a contact pressure distribution diagram in the tread contact surface of each tire. Here, the ground contact pressure of each tire was measured at 10 points in the width direction of the tread with an air pressure of 2.20 kg / cm ² and a load of 400 kg, and the tire center line CL
The values at the measurement points symmetrical with respect to were averaged. As shown in FIG. 2, the measurement points are one point A in the center rib 12a, two points B and C in the quarter rib 12b, and two points in the shoulder rib 12c with respect to the tire half section. Location D,
It is 5 places with E.

As can be seen from the tires of Example 1 and Comparative Examples 1 and 2, in the same rib, the areas B and D closer to the tread center line have a higher ground contact pressure than the areas C and E farther from the tread center line.

On the other hand, in the tire of Example 2, the contact pressure distribution in each rib was substantially uniform. Therefore, the tire of Example 2 is less likely to have uneven wear.

Next, these tires were tested for high-speed durability. The test conditions are ECE
Rule No. According to 30 high speed durability test. When evaluated in the V range, in Examples 1 and 2 and Comparative Example 1,
Although the tire was able to complete the run, the tire of Comparative Example 2 failed due to the occurrence of peeling between the rubber and the belt at the tread shoulder. That is, the tires of Examples 1 and 2 have the same high-speed durability as the tire of Comparative Example 1 reinforced by the edge ply and the cap ply.

As described above, the tires of Examples 1 and 2 were
Both high-speed durability and steering stability can be improved, and in the tire of Example 2, uneven wear can be suppressed.

[0057]

According to the pneumatic radial tire of the first or second aspect of the present invention, the number of ends of the belt layer end portion can be maintained in a dense state before the vulcanization molding. The rigidity is improved and the rigidity balance of the belt layer can be improved. Therefore, steering stability is improved. Further, since the belt reinforcing material suppresses the belt layer end portion from rising, high-speed durability is improved. Therefore,
Both high speed durability and steering stability can be improved.

Further, in the tire according to the third aspect, it is not necessary to provide an extra reinforcing material in the central portion of the belt layer, and it is possible to achieve only the above effect by wrapping both end portions of the belt layer. It is preferable in terms of tire characteristics. Further, it also contributes to the reduction of tire weight.

[Brief description of drawings]

FIG. 1 is a perspective view of a tire half section in which a pneumatic radial tire 10 according to an embodiment of the present invention is partially omitted.

2 is a partially cutaway sectional view of the radial tire 10. FIG.

FIG. 3 is a partially cutaway plan view of a belt layer 22 and a belt reinforcing member 32 of the radial tire 10.

FIG. 4 is a perspective view of a half section of a tire in which a part of a pneumatic radial tire 40 according to another embodiment of the present invention is cut away.

FIG. 5 is a partially cutaway sectional view of a radial tire 40.

FIG. 6 is a partially cutaway plan view of the belt layer 22 and the belt reinforcing member 42 of the radial tire 40.

FIG. 7 is a graph showing an end number distribution of belt cords in a belt layer.

FIG. 8 is a graph showing a contact pressure distribution on a tread surface of a tire.

FIG. 9 is a partially cutaway sectional view of a conventional radial tire 100.

[Explanation of symbols]

 10, 40 ...... Radial tire 12 ...... Tread 20 ...... Carcass layer 22 ...... Belt layer 24 ...... First belt 26 ...... Second belt 28 ...... First belt cord 30 ...... Second belt cord 32 , 34 …… Belt reinforcement material 34,44 …… Belt reinforcement material cord

Claims (3)

[Claims] 1. At least 2 between the tread and the carcass.
In a pneumatic radial tire in which a belt layer composed of a number of belts is arranged, a belt reinforcing material for bending and enclosing both end portions of the belt layer at the belt layer ends is arranged, and the belt reinforcing material is a tire. It is formed by a cord that inclines with respect to the circumferential direction, and the cord of the belt reinforcing material intersects the cord that configures the adjacent belt with an inclined direction opposite to the tire circumferential direction. Pneumatic radial tire to be. 2. The pneumatic radial tire according to claim 1, wherein the cord forming the belt reinforcing material is made of an organic fiber such as nylon, rayon or polyester. 3. The pneumatic radial tire according to claim 1, wherein the belt reinforcing material is formed of two reinforcing materials that respectively wrap around the ends of the belt layer.