JPH07164840A - Tire for high speed and heavy load - Google Patents

Abstract

PURPOSE:To provide such a tire as making the extent of high bead durability manifestable even at a time when a stadard load and any heavier load than the former have acted. CONSTITUTION:Each value of respective 100% moduli of carcass rubber 8, bead apex rubber, side packing rubber, chafer rubber and sidewall rubber is set to be 20 to 60kgf/cm<2>, 20 to 60kgf/cm<2>, 10 to 45kgf/cm<2> and 10 to 45kgf/cm<2> respectively. In addition, each value of respective loss elastic moduli of the carcass rubber, the bead apex rubber, the side packing rubber, the chafer rubber and the sidewall rubber is set to those of less than 20kgf/cm<2>, 20kgf/cm<2>, 20kgf/ cm<2>, 15kgf/cm<2> and 15kgf/cm<2> respectively. In a bead area between both upper and lower limit lines, gaps d1 and d2 between carcass cords is set to be 1/4 to two times over a diameter D of each carcass cord.

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 side packing rubber extending along the outer surface of the carcass and a chafer rubber that covers the side packing rubber and is in contact with a rim flange. A 100% modulus MA of the bead apex is 78 to 120 kgf. / Cm ² , 100-modulus MP of side-packing rubber 53-95 kgf / cm ² ,
And 100% modulus MS of chafer rubber 40 ~
It was proposed that the 100% modulus MS of 70 kgf / cm ² and the sidewall rubber be 10 to 45 kgf / cm ² and that each 100% modulus be MS <MC <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 during deformation and induces cord looseness and ply separation of the carcass, and the upper end of the bead apex rubber is locally bent due to the difference in rigidity. It is conceivable that the cord strength of the carcass is lowered, and furthermore, crack damage such as cracks is induced between the rubber due to the difference in modulus between the sidewall rubber and the chafer rubber.

Therefore, according to the present invention, a low heat-generating rubber is used for the bead apex rubber, the side packing rubber and the like, the 100% modulus value thereof is reduced conversely, and the carcass rubber is adapted to the above-mentioned physical properties of the rubber. The purpose of the present invention is to provide a high-speed heavy-duty tire capable of exhibiting high bead durability under both standard load condition and 200% standard load condition, based on the regulation of the distance between cords of the carcass.

[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 200 standard load in internal pressure state of the tire filled with mounted and normal internal pressure to the rim
A chafer rubber that extends upward in the tire radial direction including a contact area that comes into contact with the flange portion of the rim in a 200% standard state in which a% load is applied; and a sidewall rubber that extends upward from the chafer rubber in the radial direction of the tire. The modulus MP of the side-packing rubber at 100% elongation is 20 to 60 kgf / cm ² , the modulus MA of the bead apex rubber at 100% elongation is 20 to 60 kgf / cm ² , and the chafer rubber is 100%.
The modulus MC at extension is 10 to 45 kgf / cm ² and the modulus M at 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, while the bead bottom surface is filled with the internal pressure. To tire section height H
The upper limit line that intersects the tire outer surface at a point on the tire outer surface that is separated by 1/3 of the distance on the tire radial upper side, and the distance that is equal to the rim flange height HR from the bead bottom surface is separated on the tire radial upper side. In the region of the bead portion between the lower limit line that intersects the tire outer surface at a right angle at a point on the tire outer surface, the carcass has a gap between the carcass cords in each carcass ply and a gap between the carcass cords in adjacent carcass plies, 1/4 of carcass cord diameter D ~
The carcass cord is doubled to be embedded in the carcass rubber, and the modulus MO at 100% elongation of the carcass rubber is 20 to 60 kgf / cm ² and the loss elastic modulus E ″.
O is set to 20 kgf / cm ² or less.

[0009]

[Effect] Especially 100% modulus M of bead apex rubber, side packing rubber and chafer rubber
By reducing A, MP, and MC to the above range and moderately relaxing the bead rigidity, the bead deformation is dispersed in a wide range and the followability of the rubber to the carcass is enhanced. Moreover, 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 due to the increase in the amount of bead deformation can be sufficiently relaxed, and as a result, The cord loose of the carcass can be prevented and the separation between the plies and with other rubber can be suppressed. Further, the dispersion of the bead deformation can prevent local bending at the upper end of the bead apex rubber and prevent the strength of the carcass cord from being lowered at the upper end.

Moreover, since each rubber is made of a low heat-generating rubber whose upper limit of the loss elastic modulus E ″ is restricted to 20 kgf / cm ² and 15 kgf / cm ² , the temperature rise of the bead portion is suppressed, It can prevent thermal destruction of rubber.

Therefore, in combination with the above-mentioned carcass cord strength prevention effect, carcass cord looseness and ply separation prevention effect, carcass and other rubber separation prevention effect, bead temperature rise suppression effect, etc. The bead durability can be greatly improved under both conditions of 200% standard load.

[0012]

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 an internal pressure filled state in which a regular 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, an inner layer 7A composed of a carcass ply 7a among a plurality of, for example, four bead cores 2 folded back from the inside to the outside of the tire, and the inner layer 7A.
A carcass 7 is provided which covers the outer side of the inner layer 7A and surrounds the folded-back portion 71 of the inner layer 7A and is wound down from the outer side to the inner side of the tire, for example, an outer layer 7B including two outer carcass plies 7b.

The inner layer 7A has folding portions 71 at which the bead core 2 is folded from the tire inner side to the tire outer side at both ends 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.

The inner and outer carcass plies 7a and 7b are carcass rubbers, which are topping rubbers in which a carcass cord 6 made of an organic fiber cord is arranged at an angle of 70 to 90 degrees with respect to the tire equator C in this example. The sheet is covered with 8. In this example, the carcass 7 is provided between the adjacent carcass plies and the carcass cords 6 respectively.
Alternate with the circumferential direction and are inclined. 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 taper-like upper and lower portions 15 having 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 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 condition in which a load of 200% of the standard load is applied. Chafer rubber 20 including Y and extending upward in the tire radial direction
And the sidewall rubber 21 above it.

The side packing rubber 15 of 100
% Modulus MP is 20 to 60 kgf / cm ² , 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 .

Moreover, each loss elastic modulus 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 20 kgf / cm ^{2 respectively}
20kgf / cm ² or less, 20kgf / cm ² or less, 15
kgf / cm ² or less, 15 kgf / cm ² or less.

Further, an upper limit line J1 and a lower limit line J2 which will be described later are provided.
In the area of the bead 3 between and, the inter-cord distance of the carcass cord 6 is regulated. The upper limit line J1 is
As shown in FIG. 1, in the internal pressure filled state, the tire outer side surface is separated at a point Q1 on the tire outer side surface that is separated from the bead bottom surface 3A by 1/3 times the tire section height H in the tire radial direction. It is a line that intersects at a right angle. The lower limit line J2 is
A point Q2 on the outer side surface of the tire that separates a distance equal to the rim flange height HR from the bead bottom surface 3A upward in the tire radial direction.
Is a line that intersects the outer surface of the tire at a right angle. And above
The region between the lower limit lines J1 and J2 is the region where bead damage is most likely to occur, and as shown in FIG. 4, the gap d1 between the carcass cords 6 in each carcass ply 7a, 7b.
And the carcass cord 6 in the adjacent carcass plies
The gap d2 between them is both 1/4 times or more and 2 times or less the diameter D of the carcass cord. If the carcass ply is adjacent to each other, the gap d2 is not only the overlapping portion where the main body portions 70 and 73 of the inner and outer layers 7A and 7B overlap each other, but also 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-back portion 71 and the main body portion 73 of the outer layer B overlap. In addition, it is preferable that the cord array forming the carcass ply does not include a weft thread in order to reduce the variation in cord intervals.

Since the soft rubber having 100% modulus within the above range is used as the carcass rubber 8, the bead apex rubber 9, the side packing rubber 15, and the chafer rubber 20, the bead rigidity can be moderated appropriately.
The bead deformation can be dispersed in a wide range. As a result, local bending at the upper end 9a of the bead apex 9 can be prevented, and the strength of the carcass cord near the upper end 9a 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 and other rubber can be prevented.

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

The outer rubber 17 has a 100% modulus M.
Since 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, prevent rim displacement and prevent separation from the carcass, and prevent stress from propagating to the bead portion.

Further, loss elastic moduli E "O, E" A, E "
Since the low heat-generating rubber having P, E ″ 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., temperature 70 ° C., frequency 10 Hz, initial strain 10%,
It is a value measured under the condition of dynamic strain ± 1%.

The above 100% modulus MA, MP is more than 60 kgf / cm ² and 100% modulus MC, M
When S is more than 45 kgf / cm ^2, the rigidity of the bead portion 3 becomes excessive, and the strength of the carcass cord is reduced near the upper end 9a of the bead apex rubber 9 under a 200% standard load, and separation or the like is induced. Further, the 100% modulus MO is larger than 60 kgf / cm ² and the cord gap d is
When 1 and d2 are smaller than 1/4 D, the effect of relaxing the shear stress is insufficient, and cord loose, ply peeling, cracks, etc. are induced, and durability is reduced particularly at low speeds.

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 significantly impaired. Also, loss elastic moduli E ″ O, E ″ A, E ″ P are larger than 20 kgf / cm ² .
When the loss elastic moduli E ″ C and E ″ S are larger than 15 kgf / cm ² and the cord gaps d1 and d2 are larger than 2D, the bead heat becomes large and the rubber breaks. Conversely, loss elastic modulus E ″
100% when O, E ″ A, E ″ P is less than 1 kgf / cm ² and loss elastic modulus E ″ C, E ″ S is less than 1 kgf / cm ^2.
It is difficult to maintain the modulus at extension at a sufficient value, which adversely affects the running performance. Therefore, the lower limit of the loss elastic moduli E ″ O, E ″ A, E ″ P, E ″ C, E ″ S is preferably 1 kgf / cm ² .

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

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

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,
Further, by making the height HP of the upper end 15b of the side packing rubber 15 larger than this height HR, the rigidity of the bead bending portion can be effectively increased. Moreover, this height HP is
It is not necessary to make it larger than 1/2 of the tire sectional 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. This increases the joint 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.

A belt layer 10 is provided inside the tread portion 5 in the radial direction above 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 is composed of 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.

(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 Tables 1 and 2, and the high speed and high speed at the bead portion of the prototype tire were prototyped. As a load performance test, a take-off test was performed at a standard load of 20% based on the United States Civil Aviation Bureau standard TSO-C62c, and a low-speed high-load performance test was continuously run at a speed of 11 km / h at a standard load of 120%. The low speed and high load performance test was evaluated by the running distance leading to bead damage. Further, Table 3 shows an example of compounding the rubber used in Tables 1 and 2.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

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 higher 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.

3 is a cross-sectional view taken along the line I-I of FIG. 1 for explaining the cord gap.

[Explanation of symbols]

 2 bead core 3 bead part 3B bead bottom surface 4 sidewall part 5 tread part 6 carcass cord 7 carcass 8 carcass rubber 9 bead apex rubber 10 belt layer 15 side packing rubber 17 outer rubber 20 chafer rubber 21 side wall rubber d1, d2 of carcass cord Gap J1 Upper limit line J2 Lower limit line R Rim Ra Flange

Claims (2)

[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 inwardly of the portion, a tapered bead apex rubber extending upward in the radial direction between the 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. Cover the packing rubber, and the tire is mounted on the rim and is filled with the normal internal pressure. 200% loading the 200% load
The chafer rubber extends upward in the tire radial direction including a contact area that comes into contact with the flange portion of the rim in a standard state, and the sidewall rubber extends upward in the tire radial direction from the chafer rubber. Further, 100% extension of the side packing rubber is provided. 20-hour modulus MP
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 of 100% elongation of the chafer rubber is 10 to 45 kgf / cm ^2, and the sidewall rubber is 1
Modulus MS at 100% elongation is 10 to 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 loss elastic modulus E ″ S of the sidewall rubber is 15
While not more than kgf / cm ² , in the above-mentioned internal pressure filling state, at a point on the tire outer surface that is separated by 1/3 times the tire cross-sectional height H from the bottom surface of the bead, the point intersects with the tire outer surface at a right angle. In the region of the bead portion between the upper limit line and the lower limit line intersecting at right angles with the tire outer surface at a point on the tire outer surface separated by a distance equal to the rim flange height HR from the bead bottom surface on the tire radial direction upper side, the carcass is 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 to embed the carcass cords in the carcass rubber, and 20 modulus MO at 100% elongation
~ 60kgf / cm ² and loss elastic modulus E ″ O is 20kgf / cm
A high-speed heavy-duty tire with a weight of ² or less. 2. The side packing rubber has a radial height HP from a bead bottom surface to an upper end thereof which is greater 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.