JP2786804B2 - 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 tire for high-speed heavy loads which can be suitably used as an aircraft tire, and which 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 ply peeling.In addition, the upper end of the bead apex rubber becomes a local bending point due to the difference in rigidity, and the carcass cord It is conceivable that the strength is reduced, and furthermore, crack damage such as cracks is induced between the sidewall rubber and the chafer rubber due to a difference in modulus between the rubber and the like.

Accordingly, the present invention uses a low heat-generating rubber for bead apex rubber and side packing rubber, reduces the 100% modulus of the rubber, and reduces the modulus difference between the sidewall rubber and chafer rubber by 5 kgf. / Cm ² or less, and an object of the present invention is to provide a high-speed heavy-load tire capable of exhibiting high bead durability under both a standard load application state and a 200% standard load application state.

[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. And a chafer rubber extending upward in the tire radial direction including a contact area in which the tire is mounted on the rim, filled with the normal internal pressure, and in contact with the flange portion of the rim in a 200% standard state where a 200% load of the standard load is applied; A sidewall rubber extending upward from the chafer rubber in the tire radial direction; a modulus MP of the side packing rubber at 100% elongation of 20 to 60 kgf / cm ² ; and a modulus MA of the bead apex rubber at 100% elongation. 20 to
60 kgf / cm ² , the modulus MC at 100% elongation of the chafer rubber is 10 to 45 kgf / cm ^2, and the modulus MS at 100% elongation of the sidewall rubber is 1
0 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.
Hereinafter, the loss elastic modulus E ″ C of the chafer rubber is 15 kg.
f / cm ² or less and the loss elastic modulus E ″ S of the sidewall rubber is 15 kgf / cm ² or less, and the difference | MC−MS | between the modulus MC of the chafer rubber and the modulus MS of the sidewall rubber is 5 kgf. / Cm ²
It is as follows.

[0009]

[Effects] Especially 100% modulus M of bead apex rubber, side packing rubber and chafer rubber
A, MP, and MC are reduced to the above ranges, and bead stiffness is moderately reduced, thereby dispersing bead deformation in a wide range. As a result, the followability of the rubber to the carcass is enhanced, and separation with the carcass can be suppressed. In addition, this dispersion can prevent local bending at the upper end of the bead apex rubber, and can prevent the strength of the carcass cord from decreasing at the upper end. 1 between the sidewall rubber and chafer rubber
Since the rigidity difference is reduced by setting the 00% modulus difference | MC-MS | to 5 kgf / cm ² or less, it is possible to prevent the occurrence of cracks and the like between the sidewall rubber and the chafer rubber due to an increase in the bead deformation.

[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 separation from the carcass, the effect of suppressing crack damage between the side wall rubber and the chafer rubber, and the effect of suppressing the rise in bead temperature can be reduced. The bead durability under both loads can be greatly improved.

[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 the tire in a normal internal pressure state where the tire is mounted on the rim R and 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 a plurality of, for example, four, inner layers 7A formed by folding the bead core 2 from the inside to the outside of the tire, and a folded portion 71 of the inner layer 7A to surround the inside of the tire from the outside to the inside of the tire. And a carcass 7 having an outer layer 7B composed of two outer plies, for example, two outer plies.

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 ply and the outer ply use a carcass cord made of an organic fiber cord.
In the present embodiment, the carcass 7 is arranged in the radial direction having an inclination of 0 degree, and the carcass cords are alternately inclined with respect to the circumferential direction between the adjacent carcass plies. 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.

In the tread portion 5, a belt layer 10 is provided inside the carcass 7 in a 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.

In the present invention, the outer rubber 1
7 from the bottom of the bead portion 3 to the side packing rubber 1
5 and the normal internal pressure condition and the standard load of 200
The rim R is divided into a chafer rubber 20 extending upward in the tire radial direction including a contact area Y in contact with the flange Ra of the rim R and a sidewall rubber 21 thereabove in a 200% standard load state where a load of 200% is applied. . Moreover, the 100% modulus MP of the side packing rubber 15 is 20 to 60 kgf / cm ² , and the 100% modulus MA of the bead apex rubber 9 is 20 to 60 kgf / cm 2.
^2. 100% modulus MC of the chafer rubber 20
10 to 45 kgf / cm ² and the sidewall rubber 2
The 100% modulus MS of No. 1 is set to 10 to 45 kgf / cm ² . On the other hand, the difference between the 100% modulus MC and MS |
MC-MS | is set to 5 kgf / cm ² or less.

Further, the loss elastic moduli E ″ A, E ″ P, E ″ C of the bead apex rubber 9, side packing rubber 15, chafer rubber 20 and side wall rubber 21.
E ″ S is set to 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, respectively.

As described above, the bead apex rubber 9, the side packing rubber 15, and the chafer rubber 20
Since the soft rubber having the 100% modulus in the above range is used, the bead rigidity can be moderately reduced, and the bead deformation can be dispersed over a wide range. This prevents local bending at the upper end 9a of the bead apex 9,
The strength of the carcass cord in the vicinity can be prevented from decreasing.
By using the soft rubber, the followability with the carcass 7 is enhanced, and separation of the carcass 7 can be prevented.

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, since the modulus difference between the chafer rubber 20 and the sidewall rubber 21 is as small as 5 kgf / cm ² or less, the rubber 20,
21 can be prevented.

Further, the loss modulus E "A, E" P, E "
Since the low heat-generating rubber having C and E ″ S within the above range is used, it is possible to effectively suppress a rise in the temperature of the bead portion.

Here, the loss elastic modulus is 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, 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 greater than 45 kgf / cm ^2, the rigidity of the bead portion 3 becomes excessive, and under the 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.

100% modulus MA, MP is 20 kg
Less than f / cm ² and 100% modulus MC, MS is 1
If it is smaller than 0 kgf / cm ² , the required rigidity of the bead portion 3 cannot be obtained, and the running performance is greatly impaired. Also, the loss modulus E ″
A, E "P is greater than 20 kgf / cm ² and loss modulus E"
When C and E "S are larger than 15 kgf / cm ² , heat generation of the bead becomes large and rubber breakage occurs. Conversely, loss elastic modulus E" A,
E ″ P is less than 1 kgf / cm ² and the loss modulus E ″ C,
When E ″ S is less than 1 kgf / cm ^2, it is difficult to maintain the modulus at 100% elongation at a sufficient value, which adversely affects running performance.
A, E "P, E" C, E " lower limit of S is preferably 1 kgf / cm ^2.

Further, the side packing rubber 15
The height HP of the upper end 15b in the radial direction from the bead bottom surface 3A is larger than the height HA of the upper end 9a of the bead apex rubber 9 from the bead bottom surface 3A and is smaller than 1/2 of the tire section height H. The height HA of the upper end 9a of the bead apex rubber 9 is larger than the height HR of the rim flange.

The height from the bead bottom surface 3A is defined as the height from the upper edge when the bottom surface 3A is inclined as in this embodiment.

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. Side packing rubber than height HR 1
By increasing the height HP of the upper end 15b of 5, the rigidity of the bend bent portion can be effectively increased. It is not necessary to make the height HP larger than 1/2 of the tire section height H.

It is necessary that the chafer rubber 20 completely cover 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 preferably used. 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 order to further suppress the separation and the like caused by the difference in modulus between the chafer rubber 20 and the sidewall rubber 21, in this embodiment, the upper end of the chafer rubber 20 is directed 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. As a result, the side wall rubber 21
And increase the bonding area.

In the present application, 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.

(Specific Example) An aircraft 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 1, and the bead durability of the prototype tire was measured by a drum test. Was measured by

The drum test was performed under a load (92,000 L).
bs), the internal pressure (222 PSI), and the speed (30 MPH), the vehicle was run at a constant speed for a predetermined distance, and after running, the tires were disassembled and bead damage was investigated. Those damaged before the run were dismantled at that time. Table 2 shows examples of compounding of the rubber used in Table 1.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

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.

[Explanation of symbols]

 2 Bead core 3 Bead section 3B Bead bottom 4 Side wall section 5 Tread section 7 Carcass 9 Bead apex rubber 10 Belt layer 15 Side packing rubber 17 Outside rubber 20 Chafer rubber 21 Side wall rubber R rim Ra flange

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-92709 (JP, A) JP-A-3-200409 (JP, A) JP-A-3-200402 (JP, A) JP-A-3-200409 16812 (JP, A) JP-A-3-204304 (JP, A) JP-A-55-83606 (JP, A) JP-B-4-29566 (JP, B2) JP-B-58-9005 (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 axial direction outer surface of the carcass at the bead portion. And a side packing rubber having a small thickness disposed thereon, and an outer rubber forming an outer surface of the tire from the bottom surface of the bead portion to the sidewall portion. The packing rubber is covered and the tire is mounted on the rim. A chafer rubber extending radially above the tire include a contact region in contact with the flange portion of the rim at 0% 200% standard state in which a load,
A sidewall rubber extending upward in the tire radial direction from the chafer rubber, and a modulus MP of the side packing rubber when stretched by 100% is 20 to 60 kg.
f / cm ² , the modulus MA at 100% elongation of the bead apex rubber is 20 to 60 kgf / cm ² , and the modulus MC at 100% elongation of the chafer rubber is 10 to 10 kgf / cm ² .
45 kgf / cm ² and 100% of the sidewall rubber
The modulus MS during elongation is 10 to 45 kgf / cm ² , and 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, the loss elastic modulus E ″ of the chafer rubber is 15 kgf / cm ² or less, and the loss elastic modulus E ″ of the sidewall rubber. S is 15 kgf / cm ² or less, and the modulus M of chafer rubber is
Difference between C and modulus MS of sidewall rubber |
MC-MS | 5 kgf / cm ² or less high-speed heavy load tire. 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.