JP2786805B2 - High speed heavy duty 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 high-speed heavy-load tire which can be suitably used as an aircraft tire, and can exhibit high bead durability even when an abnormal load exceeding a standard load is applied.

[0002]

2. Description of the Related Art In recent years, tires used under high-load, high-speed conditions, for example, tires for aircraft, have structural durability.
Radial structures are being adopted in order to improve running performance and fuel efficiency. However, since such aircraft tires are used under conditions of high internal pressure, high load, high speed, and a large deflection of 30% or more, they are required to have higher durability than tires in other fields. Peeling damage is likely to occur at and near the carcass end due to repeated bending deformation due to a large load during rolling.

[0003] Accordingly, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 5-92709.
In the publication, a small thickness side packing rubber extending along the outer surface of the carcass and a chafer rubber covering the side packing rubber and contacting the rim flange are provided in the bead portion, and a 100% modulus MA of the bead apex is 78 to 120 kgf. / Cm ² , 100 modulus MP of side packing rubber is 53 to 95 kgf / cm ² ,
And 100% modulus MS of chafa rubber
70 kgf / cm ^2, and each 100% modulus with a 100% modulus MS of the sidewall rubber and 10~45kgf / cm ² was proposed that an MS <MC <MP <MA.

[0004] By setting the 100% modulus MA, MP of the bead apex rubber and the side packing rubber to a large value as described above, the bead rigidity can be increased, the bead deformation can be reduced, and the MC <M
As P <MA, each modulus is reduced in multiple steps toward the outside in the tire axial direction to reduce the shear stress under load.

[0005]

However, although the above-mentioned means can improve the bead durability under a standard load condition, for example, when one of the tires is punctured when using two or more wheels, an abnormal load is applied to the remaining tire. It was found that the bead durability was insufficient under a load of 200% standard load, which was assumed to act.

The reason for this is that under a large load such as a 200% standard load, the bead deformation cannot be reduced by improving the bead stiffness by bead apex rubber, side packing rubber, etc., and the 100% modulus MA Setting MP to a large value, on the contrary, impairs the ability to follow the carcass during deformation and induces cord loose and ply peeling of the carcass. In addition, the upper end of the bead apex rubber is locally bent due to a difference in rigidity. It is considered that the strength of the cord of the carcass is reduced, and furthermore, crack damage such as cracks is induced between the rubber and the sidewall rubber and the chafer rubber due to the difference in modulus.

Accordingly, the present invention uses a low heat-generating rubber for the bead apex rubber and the side packing rubber, reduces the value of the 100% modulus of the rubber, and adapts the carcass rubber to the above rubber properties. It is an object of the present invention to provide a high-speed heavy-load tire capable of exhibiting high bead durability under both a standard load state and a 200% standard load state on the basis of regulating the distance between carcass cords.

[0008]

In order to achieve the above object, a high-speed heavy-load tire according to the present invention comprises: a main body portion extending from a tread portion to a sidewall portion to a bead core of a bead portion; and a turn around the bead core. A radially structured carcass having a folded portion, a belt layer disposed radially above the carcass in the tire and inside the tread portion, and extending radially upward above the bead core and between the main body portion and the folded portion of the carcass. Tapered bead apex rubber, side packing rubber of small thickness arranged along the tire axial direction outer surface of the carcass at least in the bead portion, and forming the outer surface of the tire from the bottom surface of the bead portion to the sidewall portion And the outer rubber covers the side packing rubber from the bottom surface of the bead portion. Moreover 200 standard load in internal pressure state of the tire filled with mounted and normal internal pressure to the rim
A chafer rubber extending upward in the tire radial direction including a contact area in contact with the flange portion of the rim in a 200% standard state where a% load is applied, and a sidewall rubber extending upward from the chafer rubber in the tire radial direction. The modulus MP at the time of 100% elongation of the side packing rubber is 20 to 60 kgf / cm ² , the modulus MA at the time of 100% elongation of the bead apex rubber is 20 to 60 kgf / cm ² , and 100% of the chafer rubber.
The modulus MC at the time of extension is 10 to 45 kgf / cm ² and the modulus M at the time of 100% extension of the sidewall rubber.
S is 10 to 45 kgf / cm ² , the loss elastic modulus E ″ P of the side packing rubber is 20 kgf / cm ² or less, and the loss elastic modulus E ″ A of the bead apex rubber is 20 kgf.
/ Cm ² or less, the loss elastic modulus E ″ C of the chafer rubber is 15 kgf / cm ² or less, and the loss elastic modulus E ″ S of the sidewall rubber is 15 kgf / cm ² or less. From the tire height H
The upper limit line that intersects the tire outer surface at a point on the tire outer surface that is 1/3 of the distance upward in the tire radial direction and that is at a distance equal to the rim flange height HR from the bead bottom surface in the tire radial upper direction In the region of the bead portion between the lower limit line perpendicular to the tire outer surface at a point on the tire outer surface, the carcass has a gap between carcass cords in each carcass ply and a gap between carcass cords in adjacent carcass plies, 1/4 of diameter D of carcass cord
The carcass cord is buried in the carcass rubber with a factor of ^two, the modulus of the carcass rubber at the time of 100% elongation is 20 to 60 kgf / cm ² and the loss modulus E ″.
O is set to 20 kgf / cm ² or less.

[0009]

[Effects] Especially 100% modulus M of bead apex rubber, side packing rubber and chafer rubber
By reducing A, MP, and MC to the above ranges and moderately reducing the bead rigidity, the bead deformation is dispersed over a wide range and the followability of the rubber to the carcass is enhanced. In addition, since the distance between the cords of the carcass is restricted to 1 / 4D to 2D and the 100% modulus MO of the carcass rubber is also reduced, the shear stress between the cords caused by the increase in the bead deformation can be sufficiently relaxed. In addition, it is possible to prevent cord loose of a carcass and to suppress separation between plies and separation with other rubber. Further, the dispersion of the bead deformation can prevent local bending at the upper end of the bead apex rubber, and can prevent reduction in the strength of the carcass cord at the upper end.

[0010] Moreover, since low heat-generating rubber is used for each rubber in which the upper limit of the loss elastic modulus E ″ is regulated to 20 kgf / cm ² and 15 kgf / cm ² , the rise in the temperature of the bead portion is suppressed. It can prevent thermal destruction of rubber.

Therefore, the effect of preventing the carcass cord from being reduced in strength, the effect of preventing carcass cord loose and ply separation, the effect of preventing peeling of the carcass from other rubbers, the effect of suppressing the increase in bead temperature, etc. The bead durability can be greatly improved both under a standard load of 200%.

[0012]

An embodiment of the present invention will be described below with a tire size of 46 ×.
A 17R20 aircraft tire will be described as an example with reference to the drawings.

FIG. 1 shows a cross section of a tire mounted on the rim R and filled with an internal pressure to which a normal internal pressure is applied.
A high-speed heavy-load tire 1 (hereinafter referred to as a tire 1) includes a bead portion 3 through which a bead core 2 passes, and a sidewall portion 4 connected to the bead portion 3 and extending upward in the tire radial direction.
And a tread portion 5 connecting between the upper ends thereof.

Further, the tire 1 has an inner layer 7A composed of a plurality of, for example, four, carcass plies 7a in which the bead core 2 is folded from the inside to the outside of the tire, and the inner layer 7A.
And a carcass 7 having a plurality of, for example, two outer carcass plies 7b, which are wound down from the outside of the tire to the inside around the folded portion 71 of the inner layer 7A.

The inner layer 7A has, at both ends of a toroidal body 70 passing through the side wall portion 4 and the tread 5 portion, a folded portion 71 for folding the bead core 2 from the inside to the outside of the tire, and the outer layer 7B has a toroidal shape. The main body 73 has an unwinding portion 74 which is unwound from the outside of the bead core 2.

In this embodiment, the inner and outer carcass plies 7a and 7b are made of a carcass cord 6 having an organic fiber cord arranged at an angle of 70 to 90 degrees with respect to the tire equator C. 8 to form a sheet. In the present example, the carcass 7 has a carcass cord 6 between adjacent carcass plies.
Are alternately crossed and inclined with respect to the circumferential direction. As the organic fiber cord, rayon, polyester, vinylon, nylon, aromatic polyamide and the like can be used.

The body 70 of the inner layer 7A of the carcass 7
A bead apex rubber 9 having a tapered shape extending radially upward from the bead core 2 is disposed between the bent portion 71 and the folded portion 71. In the bead portion 3, a side packing rubber 15 having a small thickness is provided on the main body portion 73 of the outer layer 7B of the carcass 7 so as to extend vertically in the radial direction along the outer surface thereof.

As shown in FIG. 2, the side packing rubber 15 has tapered upper and lower portions 15 whose thickness is gradually reduced above and below a central portion 15A having a maximum thickness t in this example.
B, 15C form a substantially crescent shape extending.

It is preferable that the maximum thickness t is not less than 2.5 mm and not more than 4.5 mm, or not less than 0.1 times and not more than 0.18 times the diameter of the bead core 2. In addition, the side packing rubber 15 has a bead outer surface that is concavely curved outward in the tire axial direction, of the tire outer surface,
The central portion 15A is located near the inflection point position P between the convex portion and the sidewall outer side surface, and the lower portion 15C has a lower end 15a that is connected to the bead core 2.
Breaks over the height of the upper edge. The lower end 15
The reinforcement filler 16 is continuously provided along the lower surface of the unwinding portion 74 of the outer layer 7B. Then, the side packing rubber 15 is covered by the outer rubber 17 forming the outer surface of the tire from the bottom surface of the bead portion 3 to the side wall portion 4.

The outer rubber 17 covers the side packing rubber 15 from the bottom surface of the bead portion 3 and is in contact with the flange Ra of the rim R in a 200% standard load state where a load of 200% of the standard load is applied. Chafer rubber 20 extending upward in the tire radial direction including Y
And the side wall rubber 21 thereabove.

Further, 100 of the side packing rubber 15
% Modulus MP is 20 to 60 kgf / cm ² , and 100% modulus MA of the bead apex rubber 9 is 20 to 60 kgf / cm ² .
^{60kgf / cm 2, 10~45kgf / cm} 2 and the 100% modulus MC of the chafer rubber 20, 10~45kg 100% modulus MS of the sidewall rubber 21
f / cm ² and 100% modulus M of carcass rubber 8
O is set to 20 to 60 kgf / cm ² .

Furthermore, the loss elastic moduli E ″ O of the carcass rubber 8, the bead apex rubber 9, the side packing rubber 15, the chafer rubber 20, and the side wall rubber 21,
E "A, E" P, E "C, E" S were each 20 kgf / cm ²
Below, 20 kgf / cm ² or less, 20 kgf / cm ² or less, 15
kgf / cm ² or less and 15 kgf / cm ² or less.

Further, an upper limit line J1 and a lower limit line J2 described later.
In the region of the bead 3 between, the inter-cord distance of the carcass cord 6 is regulated. The upper limit line J1 is
As shown in FIG. 1, in the above-mentioned internal pressure filling state, the tire outer surface is separated from the bead bottom surface 3A by a point Q1 on the tire outer surface separated from the bead bottom surface 3A by 1 / times the tire cross-sectional height H in the tire radial direction. Lines that cross at right angles. Also, the lower limit line J2 is
A point Q2 on the tire outer surface that is separated from the bead bottom surface 3A by a distance equal to the rim flange height HR upward in the tire radial direction.
Is a line that intersects the tire outer surface at right angles. And above,
The area between the lower limit lines J1 and J2 is the area where bead damage is most likely to occur. As shown in FIG. 4, the gap d1 between the carcass cords 6 in each of the carcass plies 7a and 7b.
And carcass cord 6 in adjacent carcass ply
The gap d2 between them is at least 1/4 times and not more than 2 times the diameter D of the carcass cord. In addition, if the carcass ply is adjacent to each other, the gap d2 may be an overlapping portion where the main body portions 70 and 73 of the inner and outer layers 7A and 7B overlap with each other, as well as the main body portion 70 of the inner layer 7A and its folded portion 71. And a gap in the overlapping portion where the folded portion 71 and the main body portion 73 of the outer layer B overlap. In addition, the cord array that forms the carcass ply preferably does not include a weft thread in order to reduce variation in cord intervals.

As described above, since the carcass rubber 8, the bead apex rubber 9, the side packing rubber 15, and the chafer rubber 20 are made of a soft rubber having a modulus of 100% in the above range, the bead rigidity can be moderately reduced.
Bead deformation can be dispersed over a wide range. Thereby, local bending at the upper end 9a of the bead apex 9 can be prevented, and strength reduction of the carcass cord near the upper end 9a can be prevented. By using the soft rubber, the followability with the carcass 7 is enhanced, and the separation between the carcass 7 and another rubber can be prevented.

Moreover, the gap d1 of the carcass cord 6
Since d2 is regulated to 1/4 D to 2D, and the modulus MO of the carcass rubber 8 is reduced similarly to other rubbers, the shear stress between the carcass cords 6 can be sufficiently reduced,
As a result, cord loose of the carcass can be prevented, and occurrence of peeling between the carcass plies can be suppressed.

Also, 100% modulus M of the outer rubber 17
C and MS are 10 to 45 kgf / cm ² respectively,
It is possible to expand and contract following the rim R and the carcass 7, and it is possible to prevent the separation from the carcass while suppressing the rim displacement and to prevent the transmission of the stress to the bead portion.

Further, the loss modulus E "O, E" A, E "
Since a low heat-generating rubber having P, E "C, and E" S within the above ranges is used, a rise in the temperature of the bead portion can be effectively suppressed.

Here, the loss elastic modulus was determined by cutting a test piece from a tire and using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. at a temperature of 70 ° C., a frequency of 10 Hz, and an initial strain of 10%.
It is a value measured under the condition of dynamic strain ± 1%.

The 100% modulus MA, MP is greater than 60 kgf / cm ² and the 100% modulus MC, M
When S is larger than 45 kgf / cm ^2, the rigidity of the bead portion 3 becomes excessive, and under a standard load of 200%, the strength of the carcass cord is reduced near the upper end 9 a of the bead apex rubber 9, and separation and the like are induced. The 100% modulus MO is greater than 60 kgf / cm ² and the cord gap d.
If 1,2 is smaller than 1/4 D, the effect of alleviating the shear stress becomes insufficient, and cord loose, ply peeling, cracks, etc. are induced, and the durability particularly at low speeds is reduced.

Also, 100% modulus MO, MA, MP is less than 20 kgf / cm ² , and 100% modulus MC,
When the MS is less than 10 kgf / cm ² , the required rigidity of the bead portion 3 cannot be obtained, and the running performance is greatly impaired. Further, the loss elastic modulus E "O, E" A, E "P is larger than 20 kgf / cm ² ,
When the loss elastic moduli E ″ C and E ″ S are greater than 15 kgf / cm ² and the cord gaps d1 and d2 are greater than 2D, the bead heat is increased and rubber breakage occurs. Conversely, the loss modulus E ″
O, E "A, E" when P is 1 kgf / cm ² than the small and the loss modulus E "C, E" S is smaller than 1kgf / cm ^2, 100%
It is difficult to maintain the modulus at the time of extension at a sufficient value, which adversely affects running performance. Thus the loss modulus E "O, E" A, E "P, E" C, E " lower limit of S is preferably 1 kgf / cm ^2.

The side packing rubber 15 has a height HP in the radial direction from the bead bottom surface 3A at the upper end 15b.
Is larger than the height HA of the upper end 9a of the bead apex rubber 9 from the bead bottom surface 3A and the tire section height H
The height HA of the upper end 9a of the bead apex rubber 9 is smaller than 1/2.
It is larger than R.

The bead bottom surface 3A corresponds to the position of the nominal rim diameter (NRD) of the tire, and when the bottom surface 3A is inclined as in this example, it is defined as the upper edge position.

In order to impart bending rigidity to the bead portion, the height HA of the upper end 9a of the bead apex rubber 9 needs to be larger than the height HR of the rim flange Ra.
By making the height HP of the upper end 15b of the side packing rubber 15 larger than the height HR, the rigidity of the bead bent portion can be effectively increased. Also, this height HP,
It is not necessary to make it larger than 1/2 of the tire section height H.

It is necessary that the chafer rubber 20 completely covers the side packing rubber 15. Therefore, the height HC of the upper end from the bead bottom surface 3 A is larger than the height HP of the side packing rubber 15, and is preferable. The difference HC-HP between the height HC and the height HP is 0.5 times or more and 2.5 times or less the thickness of the chafer rubber 20.

In this embodiment, in order to suppress separation and the like due to a difference in modulus between the chafer rubber 20 and the sidewall rubber 21, the upper end of the chafer rubber 20 is moved outward in the tire axial direction and downward in the tire radial direction. The height HS of the lower end of the slope S from the bead bottom surface 3A is smaller than the height HP while being formed by the slope S. This increases the bonding area with the sidewall rubber 21.

In the present application, the carcass rubber 8, the bead apex rubber 9 and the side packing rubber 15 may be formed of the same rubber, and the chafer rubber 20 and the sidewall rubber 21 may be formed of the same rubber.

In the tread portion 5, a belt layer 10 is provided inside the carcass 7 in the radial direction above the carcass 7, and in the present embodiment, a cut is provided between the belt layer 10 and the carcass 7. The breaker 14 is interposed.

The belt layer 10 includes a plurality of, for example, eight belt plies. The cut breaker 14
For example, while a two-layer cut breaker ply is used, the cut breaker 14 extends along the carcass 7 at the center of the tread surface across the tire equator, and gradually separates from the carcass 7 outside thereof. The outer end is located at a position of about 65 to 85% of the total width W of the tire, preferably 70 to 7%.
Terminate at a position in the range of about 8%.

Further, the belt layer 10 includes the cut breaker 1
4 and its outer end extends outward beyond the outer end of the cut breaker 14 and is flush with a slope along the tire outer surface. The belt width is 70 to 85 of the tire width W.
%, And the shortest distance L1 from the outer end of the belt to the outer surface of the tire is set to a range of about 3 to 15 mm.

The belt cord forming the belt ply is:
A low-stretch elastic cord is used, and the belt cords are juxtaposed at an angle of 0 to 20 degrees with respect to the tire equator. A protective layer 18 for improving cut resistance is provided on the outer surface of the belt layer 10.

(Specific Example) An aircraft tire having a tire structure shown in FIG. 1 and a tire size of 46 × 17R20 was prototyped based on the specifications shown in Tables 1 and 2, and a high-speed height at a bead portion of the prototype tire was obtained. As a load performance test, a take-off test with a 20% standard load load based on the U.S. Aviation Administration Standard TSO-C62c was performed, and as a low-speed high-load performance test, the vehicle was continuously run at a speed of 11 km / h with a 120% standard load load. The low-speed and high-load performance test was evaluated based on a traveling distance that led to bead damage. Table 3 shows examples of compounding of the rubber used in Tables 1 and 2.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

Since the tire for high-speed heavy load of the present invention is constructed as described above, the bead durability can be greatly improved even under a standard load state and a higher load state.

[Brief description of the drawings]

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

FIG. 2 is an enlarged partial sectional view showing a bead portion.

FIG. 3 is a sectional view taken along line II of FIG. 1 for explaining a cord gap;

[Explanation of symbols]

 2 Bead core 3 Bead part 3B Bead bottom 4 Side wall part 5 Tread part 6 Carcass cord 7 Carcass 8 Carcass rubber 9 Bead apex rubber 10 Belt layer 15 Side packing rubber 17 Outside rubber 20 Chafer rubber 21 Side wall rubber d1, d2 Carcass cord Gap J1 Upper limit line J2 Lower limit line R Rim Ra Flange

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-81301 (JP, A) JP-A-5-92709 (JP, A) JP-A-3-16812 (JP, A) JP-A-4-16812 81301 (JP, A) JP-A-3-200402 (JP, A) JP-A-3-200409 (JP, A) JP-A-3-204304 (JP, A) JP 4-29566 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60C 15/00 B60C 15/06

Claims (2)

(57) [Claims] 1. A radially structured carcass having a main body portion extending from a tread portion to a bead core of a bead portion through a sidewall portion and a folded portion turned around the bead core, and a tread radially above the carcass in a tire radial direction. A belt layer disposed inward of the portion, a tapered bead apex rubber extending radially upward above the bead core and between the main body portion and the folded portion of the carcass, at least along the tire axially outer surface of the carcass at the bead portion. Side packing rubber having a small thickness, and an outer rubber forming an outer surface of the tire from the bottom surface of the bead portion to the sidewall portion, and the outer rubber is formed from the bottom surface of the bead portion to the side surface. The standard load is applied while the tire covers the packing rubber and the tire is mounted on the rim and the internal pressure is filled. 200% loading the 200% load
A chafer rubber extending upward in the tire radial direction including a contact area in contact with the flange portion of the rim in a standard state; and a sidewall rubber extending upward from the chafer rubber in the tire radial direction, and 100% elongation of the side packing rubber. Modulus of time 20 ~
60 kgf / cm ² , 100 of the bead apex rubber
The modulus MA at% elongation is 20 to 60 kgf / cm ² , the modulus MC at 100% elongation of the chafer rubber is 10 to 45 kgf / cm ^2, and
Modulus MS at 00% elongation is 10-45 kgf / c
m ² , the loss elastic modulus E ″ P of the side packing rubber is 20 kgf / cm ² or less, the loss elastic modulus E ″ A of the bead apex rubber is 20 kgf / cm ² or less, and the loss elastic modulus E ″ C of the chafer rubber is 15 kgf / cm ² or less and the side wall rubber has a loss elastic modulus E ″ S of 15
kgf / cm ² or less, while at the internal pressure filling state, intersect at right angles with the tire outer surface at a point on the tire outer surface separated from the bead bottom surface by a distance of 1/3 times the tire sectional height H in the tire radial direction upper side. In the region of the bead portion between the upper limit line and the lower limit line perpendicular to the tire outer surface at a point on the tire outer surface separated from the bead bottom by a distance equal to the rim flange height HR to the upper side in the tire radial direction, the carcass The gap between the carcass cords in each carcass ply and the gap between the carcass cords in the adjacent carcass plies are set to 1/4 to 2 times the diameter D of the carcass cords, and the carcass cords are embedded in the carcass rubber. Modulus MO at 100% elongation is 20
６０60 kgf / cm ² and loss modulus E ″ O of 20 kgf / cm 2
High-speed heavy-load tires with ² or less. 2. The side packing rubber has a radial height HP from the bead bottom surface to the upper end thereof larger than a height HA of the upper end of the bead apex rubber from the bead bottom surface and 1/1 / the tire sectional height H. 2. The high-speed heavy load tire according to claim 1, wherein the height HA of the upper end of the bead apex rubber is larger than a rim flange height HR.