JPH07144516A - Tire for high speed and heavy load - Google Patents

Abstract

PURPOSE:To display high bead durability in the standard and 200% standard load state by using low heat build-up rubber for bead apex rubber, side packing rubber, and the like, and reducing the 100% modulus value. CONSTITUTION:Outside rubber 17 is formed of side wall rubber 21 and chafer rubber 20 covering side packing.rubber 15 and extended upward including a contact area Y with a rim flange Ra in the 200% standard load state. The respective 100% moduli MP, MA, MC, MS of the side packing rubber 15, bead apex rubber 9, chafer rubber 20 and side wall 7L rubber 21 are to be 20-60, 20-60, 10-45, 10-45kg/cm<2> and to have the relation of MS<=MC<=MP<=MA. The loss elastic moduli of the bead apex rubber 9, side packing rubber 15, chafer rubber 20 and side wall rubber 2 21 are to be 20, 20, 15, 15kg/cm<2> or less. The durability of a bead can be thereby improved in both standard and abnormal load state.

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-duty 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, structural durability of tires used under high load and high speed conditions, such as aircraft tires,
A radial structure is being adopted to improve driving performance and fuel efficiency. However, since such an aircraft tire is used under conditions of high internal pressure, high load, high speed and large deflection of 30% or more, it is required to have higher durability than tires in other fields. Due to repeated bending deformation due to a large load during rolling, peeling damage is likely to occur at the carcass end and its vicinity.

Therefore, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 5-92709.
In the gazette, a bead portion is provided with a small thickness of side packing rubber extending along the outer surface of a carcass and a chafer rubber that covers the side packing rubber and is in contact with a rim flange. A 100% modulus MA of a bead apex is 78 to 120 kg. / Cm ² , 100-modulus MP of side-packing rubber is 53-95 kg / cm ² , and 100% modulus MS of chafer rubber is 40-70.
kg / cm ² and 100% modulus for each MC <
Suggested that MP <MA.

In this product, by setting the 100% modulus MA and MP of the bead apex rubber and the side packing rubber to be large as described above, the bead rigidity can be increased, the bead deformation amount can be reduced, and MC <M
By setting P <MA, each modulus is decreased in multiple steps outward in the axial direction of the tire, thereby relaxing the shear stress at the time of loading.

[0005]

However, although the above-mentioned means can improve the bead durability under the standard load condition, an abnormal load is applied to the remaining tire, for example, when one of the two tires is punctured during the use of multiple wheels. It was found that the bead durability was insufficient under the load of 200% standard load, which is supposed to work.

The reason for this is that, under a large load such as 200% standard load, the bead apex rubber, side packing rubber, etc., cannot improve bead rigidity to reduce the bead deformation amount, and the 100% modulus MA. , MP, on the contrary, impairs the ability to follow the carcass at the time of deformation and induces ply separation, and the upper end of the bead apex rubber becomes a local bending point due to the difference in rigidity, resulting in a carcass cord. It is possible to reduce the strength.

Therefore, the present invention is based on the fact that a low heat-generating rubber is used for the bead apex rubber, the side packing rubber, etc., and the value of its 100% modulus is inversely reduced. It is an object of the present invention to provide a high-speed heavy-duty tire capable of exhibiting high bead durability even under both load conditions.

[0008]

In order to achieve the above object, a high-speed heavy-duty tire of the present invention has a body portion extending from a tread portion to a side wall portion to a bead core of a bead portion, and folded around the bead core. A carcass of a radial structure having a folded portion, a belt layer arranged on the tire radial upper side of the carcass and inward of the tread portion, and extending upward in the radial direction above the bead core and between the main body portion and the folded portion of the carcass. A tapered bead apex rubber, at least a side packing rubber of a small thickness arranged along the tire axial outer surface of the carcass in the bead portion, and an outer surface of the tire extending from the bottom surface of the bead portion to the sidewall portion And an outer rubber that covers the side packing rubber from the bottom surface of the bead portion. Moreover, a chafer rubber extending upward in the radial direction of the tire including a contact region in which the tire is mounted on the rim and is filled with a normal internal pressure and is in contact with the flange portion of the rim in a 200% standard state in which a standard load of 200% is applied, A side wall rubber extending upward from the chafer rubber in the radial direction of the tire is provided, and a modulus MP of the side packing rubber at 100% extension is 20 to 60 kg / cm ² , and a modulus MA of the bead apex rubber at 100% extension. 20
˜60 kg / cm ² , the modulus MC of the chafer rubber at 100% extension is 10 to 45 kg / cm ^2, and the modulus MS of the sidewall rubber at 100% extension is 10
.About.45 kg / cm ² , loss elastic modulus E ″ P of the side packing rubber is 20 kg / cm ² or less, loss elastic modulus E ″ A of the bead apex rubber is 20 kg / cm ² or less, loss elastic modulus E of the chafer rubber E "C is 15 kg / cm ² or less and the loss elastic modulus E" S of the sidewall rubber is 1
5 kg / cm ² or less.

[0009]

[Function] In particular, each modulus MA, M of bead apex rubber, side packing rubber and chafer rubber
By reducing P and MC to the above range and moderately relaxing the bead rigidity, the bead deformation is dispersed in a wide range.
As a result, the followability of the rubber to the carcass is enhanced and the separation with the carcass can be suppressed. And this dispersion is
Prevents local bending at the top of the bead apex rubber,
It is possible to prevent the strength of the carcass cord from being lowered at the upper end.

The upper limit of the loss elastic modulus E ″ is 2 for each rubber.
Since the low heat-generating rubber regulated to 0 kg / cm ² and 15 kg / cm ² is used, the temperature rise of the bead part is suppressed,
It can prevent thermal destruction of rubber.

Therefore, in combination with the effect of preventing the reduction of the strength of the carcass cord, the effect of preventing the separation from the carcass, and the effect of suppressing the increase in the bead temperature, under the standard load and 20.
The bead durability can be greatly improved under both of 0% standard load.

Further, when MS ≦ MC <MP ≦ MA, the modulus is gradually reduced outward in the axial direction of the tire, so that the shear stress under load can be relaxed and the bead durability can be further enhanced.

[0013]

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

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

Further, in the tire 1, the bead core 2 is folded from the inside of the tire to the outside, and the inner layer 7A composed of a plurality of inner plies, for example, four inner plies, and the folded-back portion 71 of the inner layer 7A are surrounded from the outside of the tire. A carcass 7 having a plurality of, for example, two outer plies 7 </ b> B made of outer plies, is provided.

The inner layer 7A has folded portions 71 at which the bead core 2 is folded from the inside of the tire to the outside of the toroidal main body portion 70 passing through the sidewall portion 4 and the tread 5 portion, and the outer layer 7B has a toroidal shape. The main body 73 is provided with an unwinding portion 74 that is unwound from the outside to the inside of the bead core 2.

In this embodiment, the inner ply and the outer ply are carcass cords made of organic fiber cords, and the carcass cords are 70 ° to 9 ° with respect to the tire equator.
The carcass 7 is arranged in the radial direction having an inclination of 0 degree, and in the present example, the carcass cords in the adjacent carcass plies are alternately inclined with respect to the circumferential direction. As the organic fiber cord, rayon, polyester, vinylon, nylon, aromatic polyamide or the like can be used.

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

As shown in FIG. 2, the side packing rubber 15 has tapering upper and lower portions 15 with a thickness gradually decreasing above and below a central portion 15A having a maximum thickness t in this embodiment.
It has a substantially crescent shape with B and 15C extended.

The maximum thickness t is preferably 2.5 mm or more and 4.5 mm or less, or 0.1 times or more and 0.18 times or less the diameter of the bead core 2. The side packing rubber 15 includes a bead outer surface that is concavely curved outward in the tire axial direction among the tire outer surface,
The central portion 15A is disposed near the inflection point position P between the convexly curved side wall outer surface, and the lower portion 15C lower end 15a is provided at the lower end 15C.
It breaks below the height of the upper edge. Also, the lower end 15
A reinforcing filler 16 is continuously provided at a, along the lower surface of the unwinding portion 74 of the outer layer 7B. The side packing rubber 15 extends from the bottom surface of the bead portion 3 to the side wall portion 4 and is covered with the outer rubber 17 that forms the outer surface of the tire.

The tread portion 5 is provided therein with a belt layer 10 which is located on the upper side in the radial direction of the carcass 7. In this example, a cut layer is provided between the belt layer 10 and the carcass 7. The breaker 14 is interposed.

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

Further, the belt layer 10 is a cut breaker 1
4 and its outer end extends outwardly beyond the outer end of the cut breaker 14 and is aligned with a slope along the outer surface of the tire. The belt width is 70 to 85 of the total 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 be in the 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 that enhances cut resistance is provided on the outer surface of the belt layer 10.

In the present invention, the outer rubber 1 is used.
7 from the bottom surface of the bead portion 3 to the side packing rubber 1
No.5, and the normal internal pressure state and standard load of 200
%, A chafer rubber 20 that extends upward in the tire radial direction including a contact area Y that contacts the flange Ra of the rim R in a 200% standard load state and a sidewall rubber 21 above the chafer rubber 20. . Moreover, the 100% modulus MP of the side packing rubber 15 is 20 to 60 kg / cm ² , and the 100% modulus MA of the bead apex rubber 9 is 20 to 60 kg / cm ² .
1% of 100% modulus MC of the chafer rubber 20
0 to 45 kg / cm ² and 1 of the side wall rubber 21
The 00% modulus MS is 10 to 45 kg / cm ² . In addition, each modulus MP, MA, MC, MS is MS ≦ MC <
MP ≦ MA.

[0026] Moreover, the bead apex rubber 9, a side packing rubber 15, chafer rubber 20, Saidou ^Oh
Rugomu 21 of ^loss elastic modulus ^{E "A, E" P,} E "C,
E ″ ^S is 20 kg / cm2 or less, 20 kg / cm2 or less, 1
5kg / cm2 or less, 15kg / cm2 or less.

In this way, the bead apex rubber 9, the side packing rubber 15, and the chafer rubber 20 are
Since the soft rubber whose 100% modulus is within the above range is used, the bead rigidity can be moderated moderately and the bead deformation can be dispersed in 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 the separation of the carcass 7 can be prevented. Further, since each modulus is gradually reduced outward in the tire axial direction, shear stress can be relaxed.

The outer rubber 17 has a 100% modulus H
Since C and MS are 10 to 45 kg / cm @ 2 respectively, the rim R and the carcass 7 can be expanded and contracted, the separation of the carcass can be prevented while preventing the rim displacement, and the stress can be prevented from propagating to the bead portion. . Further, since the elastic difference between the chafer rubber 20 and the sidewall rubber 21 is small, the separation between the rubbers 20 and 21 can be prevented.

Further, loss elastic moduli E ″ A, E ″ P, E ″
Since the low heat-generating rubber having C and E ″ S in the above range is used, the temperature rise of the bead portion can be effectively suppressed.

Here, the loss elastic modulus was measured by cutting out a test piece from a tire and using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. at a temperature of 70 ° C., a frequency of 10, an initial strain of 10%,
It is a value measured under the condition of a dynamic strain of 2%.

The 100% modulus M ^A , MP is more than 60 kg / cm 2 and the 100% modulus MC, MS
Is greater than 45 kg / cm2, the rigidity of the bead portion 3 becomes excessive, and the strength of the carcass cord decreases near the upper end 9a of the bead apex rubber 9 under a 200% standard load.
Induce separation.

100% modulus M ^A , MP 20 kg
</ Cm2 and 100% modulus MC, MS is 10
When more kg / cm @ 2 of the small, the rigidity of the bead portion 3 need ^Re obtain et al
The driving performance is greatly impaired. Also, the loss elastic modulus E ″ A ^,
E ″ P is greater than 20 kgf / cm 2 and loss elastic modulus E ″ C,
E "when S is larger than 15 kgf / cm @ 2, the ^bead-heating becomes large rubber corruption. Conversely loss modulus ^E" A, E "
P is less than 1 kgf / cm2 and loss elastic modulus E "C, E" S
There when less than 1 kgf / cm @ 2, it is difficult to maintain a modulus at 100% elongation to a value sufficient, ^and adversely affect the traveling performance. Therefore, loss elastic modulus E ″ A, E ″
The lower limit of P, E "C, E" S is preferably 1 kgf / cm @ 2.

Further, the side packing rubber 15
The height HP of the upper end 15b of the bead apex rubber 9 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 less than 1/2 of the tire section height H. While being small, the height HA of the upper end 9a of the bead apex rubber 9 is larger than the rim flange height HR.

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

This means that the height HA of the upper end 9a of the bead apex rubber 9 must be larger than the height HR of the rim flange Ra in order to impart bending rigidity to the bead portion. Side packing rubber 1 more than height HR
By making the height HP of the upper end 15b of 5 large, the rigidity of the bead bending portion can be effectively increased. Further, it is not necessary to make this height HP larger than 1/2 of the tire cross-section height H.

Further, the chafer rubber 20 is required to completely cover the side packing rubber 15, and therefore the height HC of the upper end from the bead bottom surface 3A is larger than the height HP of the side packing rubber 15, which is preferable. The difference HC-HP with respect to the height HP is 0.5 times or more and 2.5 times or less the thickness of the chafer rubber 20.

Further, in order to suppress the separation and the like due to the modulus difference between the chafer rubber 20 and the sidewall rubber 21, in this example, the upper end of the chafer rubber 20 is directed outward in the tire axial direction and downward in the tire radial direction. While being formed by an inclined slope S, the height HS from the bead bottom surface 3A at the lower end of the slope S is smaller than the height HP. As a result, the joint area with the sidewall rubber 21 is increased, and the rigidity is gradually reduced toward the outer side in the tire axial direction in multiple stages.

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

(Specific Example) An aircraft tire having the tire structure shown in FIG. 1 and a tire size of 46 × 17R20 was prototyped according to the specifications shown in Table 1, and the bead durability of the prototype tire was tested by a drum test. Measured by

In the drum test, the load (92000L
bs), internal pressure (222 PSI), and speed (30 MPH) were run at a constant speed for a predetermined distance. After the running, the tire was disassembled to investigate the bead damage. Those that were damaged before the completion of the race were disassembled and investigated at that time. Table 2 shows a compounding example of the rubber used in Table 1.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

Since the high-speed heavy-duty tire of the present invention is constructed as described above, the bead durability can be greatly improved under the standard load condition and the abnormal load condition.

[Brief description of drawings]

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

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

[Explanation of symbols]

 2 bead core 3 bead part 3B bead bottom face 4 sidewall part 5 tread part 7 carcass 9 bead apex rubber 10 belt layer 15 side packing rubber 17 outer rubber 20 chafer rubber 21 sidewall rubber R rim Ra flange

Claims (3)

[Claims] 1. A carcass having a radial structure 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 that is folded around the bead core, an upper side in a tire radial direction of the carcass, and a tread. A belt layer disposed inward of the portion, a tapered bead apex rubber extending upward in the radial direction between the main body portion and the folded portion of the carcass above the bead core, at least along the tire axial outer surface of the carcass at the bead portion. The outer rubber forming the outer surface of the tire from the bottom surface of the bead portion to the sidewall portion, and the outer rubber is provided from the bottom surface of the bead portion to the side portion. The packing rubber is covered, the tire is mounted on the rim, the internal pressure is filled, and the standard load is 2 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 side wall rubber extending upward from the chafer rubber in the radial direction of the tire is provided, and a modulus MP when the side packing rubber is 100% expanded is 20 to 6.
0 kg / cm ^2, the bead apex 20~60kg / cm ² modulus MA at 100% elongation of the rubber, 10 to the modulus MC at 100% elongation of the chafer rubber
45 kg / cm ² and the side wall 10~45kg / cm ² modulus MS at 100% elongation of the rubber, moreover the loss modulus E "P of the side packing rubber 20 kg /
cm ² or less, the loss elastic modulus E ″ A of the bead apex rubber is 20 kg / cm ² or less, the loss elastic modulus E ″ C of the chafer rubber is 15 kg / cm ² or less, and the loss elastic modulus E ″ S of the sidewall rubber is High speed heavy duty tires with a weight of 15 kg / cm ² or less. 2. Each modulus MP, MA, MC, MS
The high-speed heavy-duty tire according to claim 1, characterized in that MS ≦ MC <MP ≦ MA. 3. The side packing rubber has a radial height HP from a bead bottom surface to an upper end thereof which is larger than a height HA of the upper end of the bead apex rubber from a bead bottom surface and is 1/1 / the tire cross-section height H. The high-speed heavy-duty tire according to claim 1, wherein the height HA of the upper end of the bead apex rubber is larger than the rim flange height HR while being smaller than 2.