JP3145814B2 - Radial tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire capable of improving structural durability and reducing the weight of a tire, and at the same time, making the thickness uniform and improving the quality.

[0002]

2. Description of the Related Art In recent years, tires used under high load and high speed conditions, such as tires for aircraft, have been adopting a radial structure in order to improve structural durability, running performance, fuel efficiency and the like. Further, as such a radial tire for aircraft, there is known a tire in which a carcass outside is loosely fastened with a belt layer and a cut breaker is provided between the carcass and the belt layer. However, such aircraft tires are used under conditions of high internal pressure, high load, and high speed, and therefore require higher durability performance than tires in other fields.

[0003] In particular, the bead portion and the end of the cut breaker
Large distortion is likely to occur due to deformation due to a large load during takeoff and landing, and bead damage and cut breaker end damage are likely to be induced. Accordingly, the present inventors have conducted various studies to determine the cause of the occurrence of these damages.

As a result, it has been found that one of the main causes is in the coding sequence of carcass and cut breaker ply.

[0005]

That is, as shown in FIG. 14, for example, a cross-woven fabric material in which cords A arranged in parallel to each other are woven by thin wefts B. Have been. Therefore, in the interwoven portion of the weft yarn A, as shown in FIG. 15, the cords A greatly vary in a zigzag manner in the thickness direction of the ply to increase the thickness of each ply, while the cords A Significantly close locally. As a result, when the tire is deformed, the shearing force acting between the cords concentrates on the adjacent portion, which becomes a weak point and induces cord loose.

[0006] In addition, the increase in the thickness of the carcass ply increases the internal temperature in the bead portion where bending deformation is large, further promoting a decrease in bead durability.

Further, in order to suppress damage to the end of the cut breaker,
At the end of the cut breaker, it may be proposed to interpose a protective rubber between the plies to absorb and reduce the shearing force concentrated at the end, but this reduces the total thickness of the tread at the shoulder to the tire equator. The tread above is locally increased compared to the thickness. As a result, the temperature of the shoulder portion is increased, and the durability of the breaker end is reduced.

When the thickness of the tread rubber on the outer side of the belt layer is reduced corresponding to the thickness of the protective rubber in order to prevent such unevenness in the total thickness of the tread, the rigidity outside the tread surface is reduced. Induces uneven wear such as excessive increase in the shoulder.

On the other hand, the present applicant has disclosed in Japanese Patent Application Laid-open No. Hei.
In the publication No. 4, the carcass cord has an elongation at a load of 5 kg of 5 to 10, or a value Ds (% / d) obtained by dividing the elongation S ₅ (%) at a load of 5 kg by the denier number of the cord is 7.35 × 1.
An elastic cord having a relatively large extensibility of 0 ^{-4 to} 14.7 × 10 ^-4 was adopted, and a large elongation was previously given to the carcass cord at the time of internal pressure filling. This has the effect of reducing the compressive stress generated in the carcass cord of the bead portion at the time of bead deformation, thereby preventing the carcass cord from being compressed and broken. However, when a carcass cord having such a large extensibility is used, there is a problem that the shearing force acting between the cords is increased due to the large elongation. It is necessary to suppress cord loose.

That is, the present invention is based on the use of plies arranged in parallel to each other in the same plane without splicing the cords with weft yarns. When the plies are used for a carcass, a necessary cord gap is maintained. The bead thickness can be reduced while the bead durability can be greatly improved. Further, when used as a cut breaker, the durability at the end of the cut breaker can be similarly improved.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, the bead portion is turned around the bead portion from the tread portion to the side wall portion and is formed at an angle of 75.degree. To the tire equator. A carcass comprising a plurality of carcass plies having carcass cords arranged at an angle of not less than 90 ° and overlapping inside and outside; a belt layer arranged radially outside of the carcass and inside the tread portion; And a cut breaker comprising one or more cut breaker plies of a breaker cord interposed between the carcass plies and at least the carcass plies arranged in parallel in the same plane without splicing the carcass cords by weft yarns. the life and death the carcass cord with forming a Umachaku sheet-shaped into the rubber, the Kakasuko
The elongation S10 (%) at 10% of the cord breaking strength is 5%.
And a gap between the carcass cords in the carcass ply overlapping the inside and outside, at least in a region from the bottom of the bead to the folded upper end of the carcass ply, having a diameter K1 of the carcass cord. On the outer surface of the tire, which is not less than 1/4 and not more than 2 times, and which is separated from the bead heel point Q of the tire 1 to which the specified internal pressure is applied by a distance L1 which is 0.2 times the height H of the tire cross section outward in the tire radial direction. Bead thickness F at reference point P
And the ratio F / X between the bead heel point Q and the length X in the tire axial direction from the bead core to the inner edge in the tire axial direction of the bead core is 0.1.
The radial tire has a diameter of 6 or less.

According to a third aspect of the present invention, there is provided a carcass cord having a bead portion which is turned around from a tread portion to a sidewall portion around a bead core and arranged at an angle of not less than 75 ° and not more than 90 ° with respect to the tire equator. A carcass comprising at least one carcass ply, and a belt layer comprising at least one ply having a belt cord located radially outward of the carcass and inside the tread portion and arranged at an angle of 5 degrees or less with respect to the tire equator. And between 0 and 7 with respect to the tire equator interposed between the carcass and the belt layer.
A cut breaker consisting of one or more cut breaker plies of breaker cords arranged at an angle of 0 ° or less, while at least said cut breaker plies are parallel to each other in the same plane without splicing the breaker cords with weft yarns. The breaker cords of the cut breaker ply are arranged in a sheet shape in which the breaker cords are embedded in rubber, and the breaker cords of the cut breaker ply have at least a distance between the ply and a cord of another ply adjacent inside and outside. In the region extending from both ends of the ply to 60% of the spread width of the ply, the breaker cord is not less than 1/4 and not more than 4 times the diameter K2.

[0013]

As described above, since the ply eliminates the weft yarn woven between the cords, it is possible to prevent the carcass cords from varying in the thickness direction in the ply.

As a result, the ply thickness per sheet can be reduced, the calorific value of the rubber can be reduced, and the weight of the tire can be reduced. In addition, since a uniform and stable cord gap between plies can be obtained, local weakness of cord loose can be eliminated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in which the tire size is four.
The case of a 6 × 17R20 aircraft tire will be described as an example with reference to the drawings.

In FIG. 1, which shows a cross section of a tire in a specified internal pressure state in which the tire is mounted on a specified rim Rm and a specified internal pressure is applied, a radial tire 1 (hereinafter referred to as a tire 1)
The vehicle includes a bead portion 3 through which the bead core 2 passes, a sidewall portion 4 extending to the bead portion 3 and extending outward in the tire radial direction, and a tread portion 5 connecting between outer ends thereof.

Further, between the bead portions 3, 3, a plurality of layers of carcass 6 formed by overlapping a plurality of carcass plies 7 inside and outside.
On the other hand, a belt layer 10 is disposed radially outward and inside the tread portion 5, and a cut breaker 11 is disposed between the belt layer 10 and the carcass 6.

The outer surface (tread surface) of the tread portion 5 is curved along a reference curve SS having a single crown radius or a double crown radius. Also, on the tread surface, two or less, in this example, two main longitudinal grooves G1 extending in the circumferential direction through the tread central portion, and at least one of the main longitudinal grooves G1 passing outside the main longitudinal grooves G1 in the tire axial direction, In this example, one sub-vertical groove G2 is provided. These four vertical grooves G
According to 1, G2, the tread surface is divided into five ribs R in this example. As shown in FIG. 13, the sub-vertical groove G2 is shallower than the main vertical groove G1, and has a groove depth f of the sub-vertical groove G2.
Reference numeral 2 denotes a groove depth f1 of the main vertical groove G1 of 0.65 to 0.95. Further, when the sub-vertical groove G2 or, for example, a plurality of sub-vertical grooves is formed on both outer sides of the main vertical groove G1, the outermost sub-vertical groove G2a in the tire axial direction is the tire sectional width from the tire equator C. It is formed in a region separated by a distance J of 0.215 to 0.31 times W. Also, the outermost sub-vertical groove G2a
Outer surface S of the inner adjacent rib Ra adjacent to the inner side in the tire axial direction
Ra is inclined radially inward toward the outside in the tire axial direction with respect to the reference curve SS. That is, the rib thickness r1 that is the height of the outer end E1 of the inner adjacent rib Ra from the bottom of the sub-vertical groove G2 is smaller than the rib thickness r2 of the inner end E2 of the outer adjacent rib Rb, and the ratio r1 / r2 is set to 0.75 to 0.95 in this example. Here, the outer adjacent rib Rb refers to a rib adjacent to the sub longitudinal groove G2a on the outer side in the tire axial direction. Further, the vertical groove depths f1 and f2 are the depths from the reference curve SS to the groove bottom, and the groove depth f2
And the rib thickness r2 substantially coincide with each other.

Since the tread surface is formed as described above, shoulder wear, particularly at the outermost rib Rb on the outermost side, is suppressed, and the life of the tread wear can be extended. This is because, for example, in the case of an aircraft tire for large-size transportation having a deflection rate of 30 to 35%, for example, a ground contact is made at a distance J of 0.215 to 0.310 times the tire width W from the tire equator C. The pressure is at its maximum. Then, at the outer ribs, the contact pressure decreases rapidly toward the tread edge, and uneven wear such as shoulder drop wear occurs. Therefore, by forming the tread surface as described above, the contact pressure at a position separated by the distance J can be reduced.

In this embodiment, the carcass 6 has a plurality of, for example, four, carcass plies 7a which are turned around the bead core 2 from the inside to the outside of the tire.
And a plurality of, for example, two outer carcass plies 7 surrounding the folded portion of the inner layer 7A and rolling down from the outside to the inside of the tire.
b, 7b.

The carcass ply 7a in the tread portion 5
At both ends of a toroidal body portion 70 extending from the side wall portion 4 to the bead portion 3, a turn-back portion 71 for turning around the bead core 2 from the tire inner side to the outer side is provided, and the outer carcass ply 7 b is At both ends of the toroidal main body 73, there are provided unwinding portions 74 unwound outside the bead core 2.

Each of the inner and outer carcass plies 7a and 7b has a carcass cord 18 arranged at an angle of 75 ° to 90 ° with respect to the tire equator. In this embodiment, the carcass 6 is located between the carcass plies overlapping inside and outside. The carcass cords 18 are superposed in different directions so that the carcass cords 18 alternately cross and incline in the circumferential direction.

In the present embodiment, the bead portion 3 is provided with a bead apex 9 which rises in a tapered shape from the bead core 2 and passes between the main body portion 70 and the folded portion 71. 4, the tread portion 5 is provided with a belt layer 10 via a cut breaker 11 inside the tread portion 5 at a position radially outside the carcass 7.

In this embodiment, the carcass cord 18 has an elongation S at 10% of the breaking strength.
₁₀ (percent) using a high stretch elastic cord which is 5 to 10
And the carcass cord 18 has a breaking strength of 20.
The elongation S ₂₀ (%) at% is 9 to 15, and the elongation S ₄₀ (%) at 40% of the breaking strength is 14 to 20.

[0025] As the carcass cords 18, the value D ₁₀ obtained by dividing the elongation S ₁₀ when 10% of the breaking strength (%) in denier of the cord 7.35 × 10 ^-4 ～14.7〓 × 10 ^{- 4} ,
Further, a value D _{20 obtained} by dividing the elongation S ₂₀ (%) at 20% of the breaking strength by the denier number, the elongation S at 40% of the breaking strength.
_The value D _{40 obtained} by dividing ₄₀ (%) by the denier number is 13.2 ×
10 ^{-4 to} 22.1 × 10 ^-4 , 20.5 × 10 ^{-4 to} 29.
An elastic cord of 4 × 10 ⁻⁴ is also preferably used.

Such an elastic cord has characteristics of a region sandwiching the lower limit curves a1 and a2 and the upper limit curves b1 and b2 in FIGS. The elastic cords are represented by curves a and b (a by combining curves a1 and a2, b by combining curves b1 and b2).
(Referred to collectively as ")", when the load is small, the elongation is large, and the elongation decreases as the load increases.

By using an elastic cord having such characteristics, the carcass cord undergoes large elongation together with the internal pressure filling at the initial stage of the internal pressure filling.

When the load further increases to 20% or 40% of the breaking load, the carcass cord elongates as the load increases, but the elongation decreases gradually.

As shown by a curve c in the conventional code,
The rise is larger and substantially linear compared to the curve a. Accordingly, when such a conventional cord is used, the elongation of the carcass cord is small even when the internal pressure is charged, and the carcass cord is inferior in the ability to relieve the compressive stress acting upon deformation. Trigger.

On the other hand, the elastic cord of the present embodiment can improve the durability of the tire because it has the characteristics of the region between the curves a and b. For this reason, as described above, the elastic cord has an elongation (%) under load of elongation S ₁₀ (%) at 10% of the breaking strength of 5 or more and 10 or less, preferably 5 or less.
More than and equal to or less than 8. Elongation S at 20% of breaking strength
₂₀ (%) is 9 or more and 15 or less, preferably 10 or more and 12 or less.

In another example, a value D obtained by dividing each elongation S (%) by a denier number d is set as described above.

The breaking strength is 10%, preferably 20%.
The percentages of elongation S ₁₀ , S ₂₀ , and S ₄₀ at the time of% and 40% determine the value itself of the elongation of the cord due to the load irrespective of the denier number of the carcass cord used. On the other hand, the definition of the value obtained by dividing the elongation S ₁₀ at 10% of the breaking strength by the denier number means the elongation percentage at 10% of the breaking strength per denier of the cord. We understand mainly from the characteristics of the code. Therefore, the latter can be used for a wide range of heavy-duty high-speed tires, including aircraft tires. In the former, it means the elongation of the cord at 10% of the breaking strength without asking the denier number as described above,
It can be suitably used mainly as an aircraft tire, and also as a tire for a large jet machine.

The initial elastic modulus E _{s of the} elastic cord (kg / c)
m ² ) is at least 130, preferably at least 140 and 200
The following is assumed. The initial elastic modulus E _s (kg / cm ² ) is defined as a load (k) using a constant-speed elongation type tensile tester as shown in FIG.
g) -Elongation (%) A curve U is drawn, and is a value defined as a gradient of a tangent Y to the curve U at an elongation of 7%, and is an initial elastic modulus E _s (kg / cm ^{2) as} compared with a conventional elastic cord. By reducing the value of ()) in the above range, the extensibility of the elastic cord can be increased, and the carcass cord can be given elongation.

As the elastic cord, those having a load at break, that is, cord strength of 20 kg or more, preferably about 40 kg or more and about 60 kg or less can be suitably used. Further, as the elastic cord, a nylon cord, a polyester cord, an aromatic polyamide cord, a carbon cord, and a hybrid cord of one or more cords among metal cords can be used.

Further, such a highly extensible carcass cord 1
To suppress the carcass cord loose at the bead portion 3 in particular increased by 8 adoption of each carcass ply 7
Meanwhile, while adopting a novel structure in which the carcass cords 18 are arranged flat without variation in the thickness direction of the ply,
As shown in FIG. 3, the gap i2 between the carcass cords 18 in the carcass plies 7, 7 overlapping inside and outside is set to be at least 1/4 times and not more than 2 times the diameter K1 of the carcass cords 18.

That is, the carcass ply 7 is a sheet body in which a cord arrangement body 20 in which carcass cords 18 are arranged in parallel on the same plane without being joined by a weft is embedded in a doping rubber 19.

Therefore, compared with the conventional ply using the fabric of the blind weave, the thickness of the ply can be greatly reduced while the coating thickness of the topping rubber is kept equal, and the internal heat generation is reduced. In addition, the weight can be reduced. Moreover, the carcass cord 1 between the plies 7, 7 overlapping inside and outside
8 can be prevented from locally approaching, so that the starting point of the cord loose can be eliminated, and the vertical runout (RRO), lateral runout (LRO), etc. of the tire can be reduced by improving the uniformity. Driving performance can be improved.

In order to effectively prevent thermal destruction due to internal heat generation, as shown in FIG. 1, the tire section height H of the tire 1 to which a specified internal pressure is applied is radially outward from the bead heel point Q in the tire radial direction. The ratio F / of the bead thickness F at the reference point P on the outer surface of the tire separated by a distance L1 twice and the length X in the tire axial direction from the bead heel point Q to the inner edge of the bead core 2 in the tire axial direction. It has been found that X is desirably 0.6 or less, and the ratio F / X can be set smaller by employing the carcass ply having the above structure.

Further, as shown in FIG. 2, the cut breaker 11 connects the breaker cord 27 with respect to the tire equator by 0-7.
For example, two plies 11a1, 1 arranged at an angle of 0 degree
1a2, each ply having a breaker cord 27
Are oriented differently so that they cross each other between plies.
In this example, the width W1 of the outer ply 11a1 in the tire axial direction is smaller than the width W2 of the inner ply 11a2 adjacent on the inner side and the width B3 of the ply 10a1 of the belt layer 10 adjacent on the outer side. The dispersion of the stress is measured by setting and changing the position of each ply end. The width W2, which is the maximum width of the cut breaker, is the tire sectional width W.
Is set to 70 to 85%, more preferably 73 to 78%. The width W1 may be set equal to or wider than the widths W2 and W3.

The cut breaker 11 has a tread 5
In order to increase the in-plane bending stiffness and to increase the cornering force, the carcass cord 18 and the belt cord 26 are arranged in a triangle structure. That is, the carcass cord 18 and the belt cord 26
And the respective break angles of the breaker code 27 are different from each other. Carcass cord 18 is 75 with respect to tire equator
Since the belt cord 26 is tilted at an angle of 5 degrees or less, the breaker cord 27 is preferably tilted at an angle of 10 to 45 degrees, more preferably 10 to 30 degrees with respect to the tire equator, to form a strong triangle. Form the structure. When the carcass cord 18 has an angle of 75 to 80 degrees, the inclination of the breaker cord 27 with respect to the tire equator can be set to be close to 0 degrees.

As described above, the addition of the cut breaker 11 itself and the carcass cord 1 as described above
8. The belt cord 26 and the triangle structure increase the in-plane bending stiffness, increase the cornering force, and suppress the generation of the standing web.

[0042] And, the due to the formation of the cut breaker 11, such as this, in order to suppress the ply end peeling to proceed from the respective ends of the ply 11a1 and 11a2, each ply 11a1 and 11a2, the carcass It has a structure that is approximately the same as the ply.

That is, each of the plies 11a1 and 11a2
This is a sheet body in which a cord array 20 in which the breaker cords 27 are arranged in parallel on the same plane without being joined by weft yarns is embedded in a topping rubber 19.

Accordingly, as in the case of the carcass ply, the ply thickness can be greatly reduced while keeping the coating thickness of the topping rubber equal to that of the conventional ply. Also, internal heat generation can be reduced and weight can be reduced. Moreover, in order to prevent local proximity of cords between adjacent plies, the distance e between cords over the entire width of the plies is reduced to the minimum necessary for absorbing and relaxing the shear stress acting between the plies. Can be set to a range.

The inter-cord distance e means a distance between the cords measured in a direction perpendicular to the outer surface of the ply of the cut breaker 11, as shown in FIG. The code distance e
Is the distance e1 between the breaker code 27 of the outer ply 11a1 and the breaker code 27 of the inner ply 11a2,
Outer ply 14a1 breaker cord 27 and belt layer 1
0, including the distance e2 between the innermost ply 10a1 and the belt cord 26, and the distance e3 between the breaker code 27 of the inner ply 14a2 and the carcass cord 18 of the outermost ply 7b1 of the carcass 7. In the invention, each distance e
1, e2 and e3 are 1/4 of the diameter K2 of the breaker cord 27.
The shear force is reduced by the rubber elasticity of the topping rubber 19 interposed between the cords. Note that the regulation of the distances e1, e2, and e3 must be achieved at least in a region N extending from both ends of the ply to 60% of the ply development width.

The belt layer 10 has a plurality of layers, for example, 8 layers.
A multilayer body composed of a plurality of belt plies 10a, the outer end of which is in contact with the cut breaker 11 and extends beyond the outer end of the cut breaker 11, and is formed by a slope 10S along the tire outer surface SB. One. Belt layer 10
Is a belt width WB of about 70 to 85% of the tire sectional width W.
By restraining the carcass 6 with a tag effect, the rigidity of the tire together with the cut breaker 11 is increased, and the running performance and the like are improved.

In the belt layer 10, the shortest distance tB between the slope 10S and the tire outer surface SB is set to about 3 to 15 mm. The belt ply 10a is formed of a fabric material in which a belt cord is inclined at an angle of 0 to 5 degrees with respect to the tire equator. In the first invention, the belt cords 26 can be arranged at an angle of 0 to 20 degrees, but preferably in the range of 0 to 5 degrees.

Since the carcass ply 7 and the cut breaker ply 11 used in the present invention eliminate the restraining force of the weft yarn, they can be arranged with high precision in the same plane. Since the breaker code 27 is independent, the code arrangement may be significantly disturbed during the formation process. However, the formation has become possible by adopting a new means devised by the present inventors. That is, as shown in FIGS. The tape-like body 35 having a uniform thickness and width is formed by applying rubber with a coating thickness. Thereafter, the tape-shaped member 35 is placed on a drum 36 having an outer dimension according to the tire size.
A single-layer cylindrical body 37 is spirally wound, and is cut along a slit 38 on a drum extending in the width direction to form a wide and uniform sheet-like carcass ply. The guide 31 has, for example, a block shape in which guide holes 39 for inserting the cords are formed on the same straight line at an equal pitch as shown in FIG. 9, and uses a tension acting between the bobbin 30 and the pressing roller 40. Thus, the cords are arranged in parallel on the downstream side in the same plane. The die 33 communicates with a rubber extruder 41 and has a rubber chamber 42 through which the cord alignment body 20 passes.
3A and an end member 33B detachably attached to the front and rear ends of the rubber chamber 42 and having a hole 43 for molding.
B is a tape-shaped body 3 having a cross section corresponding to the opening shape of the hole 43 and having the code alignment body 20 buried in the center thereof, since the hole 43 is arranged concentrically with the cord alignment body 20.
5 may be formed. The base 33A is provided with a rubber chamber 42.
A take-out port 42A for taking out the surplus rubber is provided.

Further, it can be formed by using other means shown in FIGS. That is, the drum 23 having the positioning fitting grooves 22 for receiving the lower surfaces of the cords 18 and 26 arranged side by side.
And a plurality of cords 18 and 26 supplied to the drum 2
3 are supported in parallel with each other on the outer peripheral surface. The topping rubber piece 19A extruded on its outer surface is rubberized with a uniform thickness.
A similar topping rubber piece 19B is attached to the other surface of the code array body 20 with reference to the outer surface of 9A.

As a result, the cords 18 and 26
In 9, they are arranged in parallel in the same plane without dispersion in the thickness direction.

Here, "arranged in the same plane" means that the carcass cords 18 are arranged from the reference plane S as shown in FIG.
Diameter K1 or 1/1 of diameter K2 of breaker cord 26
It means that the carcass cords 18 or the breaker cords 26 are arranged in parallel between the upper and lower critical planes S1 and S1 separated by a distance Lo of 0 times, with the center thereof positioned.
Is preferably no more than 1/12 times the diameter K, more preferably 1
/ 14 times or less.

The diameters K1 and K2 are the diameters of the smallest circumscribed circles circumscribing the carcass cord 18 or the breaker cord 26. In the present invention, the shear force acting between the cords is reduced. As described above, in the carcass 6, the gap i2 is set to 1/4 to 2 times the diameter K1 and the cut breaker
In this case, the gaps e1, e2, and e3 are each 1/4 of the diameter K2.
It is restricted to a range of up to four times.

In order to improve the bead durability,
The both ends of the plies adjacent to each other are particularly important. Therefore, the regulation of the gap i2 between the carcass cords in the adjacent carcass plies overlapping inside and outside at least extends from the bottom of the bead to the folded upper end Z2 of the carcass 6. Need to be achieved in the region M over the length of
If the gap i2 is less than 1/4 of the diameter K, the effect of alleviating the shear stress becomes insufficient and cord loose is caused. If the diameter exceeds twice the diameter K1, the thickness of the tire is excessively increased, which causes an increase in the weight of the tire, and an increase in the internal temperature, thereby inducing thermal destruction of the rubber. Similarly, in the cut breaker 11, it is necessary that the inter-cord distance e is 1/4 to 4 times the diameter K2 in a region extending from the end of the cut breaker ply to 60% of the width of the ply. If the inter-cord distance e is less than 1/4 of the diameter K2, the effect of alleviating the shearing force cannot be expected, and if it exceeds 4 times, the heat generation becomes large.

If the carcass plies 7 are adjacent to each other, the gap i2 is between the body portions 70 of the inner layer 7A, between the folded portions 71 of the inner layer 7A, between the body portions 73 of the outer layer 7B, and between the body portions 73 of the outer layer 7B. Between the unwinding section 74, between the folded section 71 and the main body section 70, between the folded section 71 and the main body section 73,
And a gap between the unwinding section 74 and the main body section 70.

The regulation of the gap i2 has been made possible by using a new carcass ply from which wefts have been eliminated. In addition to the extensible carcass cord, a low-extensible carcass cord such as steel can also be used.

The cut protector 16 disposed outside the belt layer 10 is composed of at least one ply 16a using the protection cord, in this example, two plies 16a. In addition to improving the performance, the rigidity step between the belt layer 10 and the rubber of the tread portion 5 is reduced, and the shear stress therebetween is reduced.

Therefore, it is preferable that the cut protector 16 is disposed on the entire surface of the belt layer 10. Belt layer 1
In order to allow a preferable deformation to 0, the cord angle with respect to the tire equator may be made close to 0 degree to give the protective cord extensibility.

Further, the cut protector 16 may be formed of two or more layers, in addition to using one layer of ply.
Further, as shown in FIG. 2, a rubber layer 15 may be provided between the belt layer 10. The rubber layer 15 facilitates removal of the cut protector 16 without damaging the belt layer 10 during tire rehabilitation.

Also, in the present invention, the 90% of the total tread thickness TA on the tire equator CO and 90% of the length L from the tire equator CO to the ground end PA in the normal state is separated from the tire equator CO by 90%. The thickness ratio TB / TA to the total tread thickness TB at the point B is set to 1 or less. The tread total thicknesses TA and TB are the total thickness from the tread surface measured in a direction perpendicular to the tread surface to the inner surface facing the tire bore, and the use of the cut breaker 11 allows the belt layer 10 at the grounding end to be used. The thickness ratio TB / TA can be 1 or less without significantly reducing the thickness tB of the tread rubber from the outer surface to the tread surface as compared with the thickness tA of the tread rubber at the tire equator CO. Thereby, the bending stiffness of the shoulder portion is relatively reduced, and a tire profile with a small bead deformation is obtained.

(Specific Example) The tire structure shown in FIG.
Table 1 shows aircraft tires with a tire size of 46 × 17R20.
And a high-speed durability and a low-speed durability at a bead portion of the prototype tire were measured.

As a high-speed endurance test, a takeoff test based on the U.S. Aviation Administration Standard TSO-C62c was performed 100 times under a 150% reference load, and the presence or absence of carcass rubber breakage at that time was evaluated. The bead heat generation index is a value obtained by dividing a temperature difference obtained by subtracting a bead temperature before traveling from an average bead heat generation temperature after traveling 100 times by a bead temperature before traveling.

As a low-speed endurance test, the vehicle was continuously run at a speed of 11 km / H under a reference load of 120%, and the running distance leading to bead damage at that time was evaluated.

Similarly, a tire having the tire structure shown in FIG. 1 and a tire size of 46 × 17R20 was prototyped based on the specifications shown in Table 2, and the durability of the prototype tire was compared with that of a comparative example.

In the endurance test, 120%
Under load, the vehicle was continuously driven up to 3000 km at a running speed of 11 km / h, and the damage at that time was compared. Further, the cornering force is measured by using an indoor testing machine, and is indicated by an index with the value when the cut breaker is excluded being taken as 100. The higher the number, the better.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

As described above, the radial tire according to the first aspect of the present invention regulates each gap between carcass cords by using a new carcass ply from which wefts are eliminated. The bead durability can be improved, the tire can be reduced in weight, and the uniformity can be improved. According to the third aspect of the present invention, separation at both ends of the cut breaker can be suppressed without causing damage to the bead and adverse effects of uneven wear.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing a tread portion.

FIG. 3 is a sectional view illustrating a cord gap of a carcass ply.

FIG. 4 is a perspective view illustrating a distance e between cords of the cut breaker.

FIG. 5 is a diagram showing characteristics of a carcass cord.

FIG. 6 is a diagram showing characteristics of a carcass cord.

FIG. 7 is a diagram illustrating an initial elastic modulus.

FIG. 8 is a diagram illustrating one means of forming a ply.

FIG. 9 is a diagram further explaining the one means.

FIG. 10 is a diagram illustrating another means for forming a ply.

FIG. 11 is a diagram further explaining the other means.

FIG. 12 is a cross-sectional view illustrating a ply.

FIG. 13 is a partial cross-sectional view of the tread illustrating a main longitudinal groove and a sub longitudinal groove.

FIG. 14 is a cross-sectional view illustrating a conventional technique.

FIG. 15 is a cross-sectional view illustrating a conventional technique.

[Explanation of symbols]

 2 Bead core 3 Bead section 4 Side wall section 5 Tread section 7 Carcass 7a, 7b Carcass ply 10 Belt layer 11 Cut breaker 11a, 11b Cut breaker ply 18 Carcass cord 26 Breaker cord i2 Gap e, e1, e2, e3 Distance

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-57702 (JP, A) JP-A-3-21504 (JP, A) JP-A-61-229515 (JP, A) 125611 (JP, A) JP-A-4-331604 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 9/08 B60C 9/04 B60C 9/18

Claims (3)

(57) [Claims] 1. A carcass cord having a bead core turned around from a tread portion to a sidewall portion and extending at an angle of not less than 75 ° and not more than 90 ° with respect to the tire equator, and overlapping inside and outside. A carcass composed of a plurality of carcass plies, a belt layer disposed radially outside of the carcass and inside the tread portion, and one or more cut breaker plies of a breaker code interposed between the carcass and the belt layer. while comprising a cut breaker composed of at least said carcass ply, together form a Umachaku sheet-shaped rubber in parallel arrangement to and the carcass cords to each other in the same plane without splicing by weft carcass cords, the The carcass cord has an elongation at 10% of the cord breaking strength.
And S10 (%) are from 5 to 10 high-stretch elastic cords.
And the gap between the carcass cords in the carcass ply overlapping the inside and outside is at least 1/4 times and not more than 2 times the diameter K1 of the carcass cord at least in the region from the bottom of the bead to the folded upper end of the carcass ply. , And the bead heel point Q of the tire 1 with the specified internal pressure
A bead thickness F at a reference point P on the outer surface of the tire at a distance L1 that is 0.2 times the cross-sectional height H of the tire radially outward from the tire, and an inner edge of the bead core in the tire axial direction from the bead heel point Q A radial tire having a ratio F / X to the tire axial length X up to 0.6 or less. 2. The carcass cord has a cord breaking strength.
Divide the elongation at 10% S10 (%) by the denier of the cord
Value D10 (% / d) is 7.35 × 10 ^{-4 to} 14.7 × 1
0 Rajiaruta of claim 1, wherein the ^-4
No. (3) A side wall portion is extended from a tread portion to a via hole.
Around the bead core of the bead section and on the tire equator
Carcass arranged at an angle of 75 ° or more and 90 ° or less
Car consisting of one or more carcass plies with scord
Kas and, radially Direction outer and the tread portion of the carcass
It is located inside and less than 5 degrees to the tire equator
From one or more plies with belt cords arranged at an angle
Belt layer, interposed between the carcass and the belt layer
And at an angle of 0 to 70 ° with respect to the tire equator.
One or more cut breaker ply
At least in front of the
For the cut breaker ply, the breaker cord is
Arranged parallel to each other in the same plane without
With the form of a sheet in which the laser code is embedded in rubber
The breaker code of the cut breaker ply is
The distance between the lie and the cords of other adjacent plies inside and outside
From at least both ends of the ply,
In the region over 60%, the diameter K of the breaker cord
Radial tires that are 1/4 times or more and 2 times or less than 2 times.