JPH0592709A - High speed and heavy load tire - Google Patents

Abstract

PURPOSE:To reduce bending deformation and heat generation in a bead part, suppress damages of chafing or the like, and improve the bead durability in the basic design where the outside rubber is divided into a chafer rubber and a side wall rubber which are provided with specified moduli respectively. CONSTITUTION:A tire is provided with at least an outside rubber 17 forming the outside surface of a tire from the bottom side surface of a bead part to a side well part. The outside rubber 17 is divided into a chafer rubber 20 including a region (Y) which is brought into contact with a flange RA of a regular rim (R) in the 200% load condition, and a side wall rubber 21 located above the chafer rubber. The respective 100% module MP, MA, MC, MS of the side packing rubber 15, the bead apex rubber 9, the chafer rubber 20 and the side wall rubber 21 are set to 53-95kg/cm<2>, 78-120kg/cm<2>, 40-70kg/cm<2>, 10-45kg/cm<2>, in order. The respective moduli are set to satisfy the relationship MS<MC<MP<MA.

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 capable of reducing bead deformation and heat generation of bead, suppressing damage such as rim chafing, and improving bead durability.

[0002]

2. Description of the Related Art In recent years,
Even in tires used under high load and high speed conditions, for example, aircraft tires, radial structure tires are being adopted in order to improve structural durability, running performance, fuel efficiency, and the like. However, since such aircraft tires are used under conditions of high internal pressure, high load, and high speed, they are required to have higher durability performance than tires in other fields, and in particular, the bead part is bent by a large load during takeoff and landing. Peeling damage is likely to occur at the carcass edge and its vicinity due to the strain caused by deformation, and therefore, conventionally, by increasing the bead volume, using a reinforcing layer composed of organic and inorganic fiber cords, the rigidity of the bead portion is increased, and the bending Deformation is controlled.

However, such a rigidity strengthening measure cannot reduce internal heat generation due to bending deformation, and has not achieved a satisfactory effect of preventing damage to the bead portion.

Therefore, the present inventors have accumulated various studies on the bending deformation of the bead portion by using a take-off taxi simulation test based on the United States Civil Aviation Bureau standard TSO-C62c. As a result, when comparing the no-load tire bead portion AO shown in FIG. 3 mounted on the regular rim R and filled with the regular internal pressure with the tire bead portion A1 under the regular load, the inside of the bead portion is compared. As shown in FIG. 4, the heat generation is, for example, each length between the outer surface of each bead portion AO, A1 and the upper edge of the rim flange Ra, that is, the initial height on a perpendicular line rising from the outer edge of the rim flange Ra. It was found that the smaller the bead deformation amount h0-h1 which is the difference between h0 and the load height h1, the lower the bead deformation amount h0-h1.

Further, as a result of the accumulation of further studies, the present inventors have increased the load height h1 by placing a rubber having a relatively high modulus in the bead apex with almost no change in the initial height h0. Deformation amount h0-h1
It was found that the shear stress generated in the bead portion under load can be relieved and the bead durability can be improved by reducing the modulus from the inside to the outside in multiple steps.

Therefore, the inventors of the present invention have filed Japanese Patent Application No. 1-3446.
No. 38, a bead portion is provided with a small thickness of side packing rubber that extends along the outer surface of the carcass, and the bead apex has a 100% modulus MA of 78 to 120.
kg / cm ² , 100 modulus M of side packing rubber
P is 53 to 95 kg / cm ² , and 100% modulus MS of the outer rubber that covers the side packing rubber and extends from the bead portion to the sidewall portion is 14 to 50 kg / cm ^2, and each 100% modulus is MS <MP < Proposed to be MA.

However, in this case, since the outer rubber is formed of a single and soft rubber material over the entire length thereof, it is easy to cause external damage such as chafing between the outer rubber and the rim flange Ra at the time of bead deformation. Moreover, it has been found that cracks and the like progress early from the external damage and impair the bead durability.

Therefore, the present invention is based on the fact that the outer rubber is divided into a chafer rubber and a sidewall rubber each having a predetermined modulus, and is caused by a rim shift while reducing bead bending deformation and bead heat generation. An object of the present invention is to provide a high-speed heavy-duty tire capable of suppressing external damage such as chafing and improving bead durability.

[0009]

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 sidewall portion to a bead core of a bead portion, and folded around the bead core. A carcass having a radial structure having a folded portion, a belt layer disposed 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 small thickness side packing rubber 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% of the normal load with tire filling mounted in a normal rim and standard pressure
In addition to 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 regular rim in a loaded 200% load state, and a sidewall rubber that extends upward from the chafer rubber in the radial direction of the tire, 100% of the side packing rubber
The modulus MP at extension is 53 to 95 kg / cm ² , and the modulus M at 100% extension of the bead apex rubber.
A of 78 to 120 kg / cm ² , 10 of the chafer rubber
0% elongation at a modulus MC 40~70kg / cm ² and the side wall of the modulus MS at 100% elongation of the rubber 10~45kg / cm ^2, yet each modulus M
P, MA, MC, and MS are set as MS <MC <MP <MA.

[0010]

The bead apex rubber has a modulus at 100% elongation, that is, a 100% modulus of 78.
A high hardness rubber of 120 kg / cm ² is used. This increases the bead rigidity and reduces the bead deformation amount h0-h1. Further, of the outer rubber forming the tire outer surface, the chafer rubber extending from the bottom surface of the bead portion including the contact area with the flange has a relatively soft 100% modulus of 40.
Use ~ 70 kg / cm ² and 10
A side packing rubber having a 0% modulus of 53 to 95 kg / cm ² and smaller than the bead apex rubber and larger than the chafer rubber is interposed. As a result, the bead rigidity is further increased, and at the same time, the shear stress at the time of bead deformation is relaxed and the bead durability is increased. Moreover, chafer rubber has a 100% modulus of at least 40.
Since it is kg / cm ² or more, the occurrence of external damage such as rim slippage can be suppressed. As described above, the bead damage can be suppressed by the synergistic effects of the bending stress and the deformation heat generation reducing effect due to the reduction of the bead deformation amount, the shear stress relaxing effect, and the external damage suppressing effect.

Since the sidewall rubber extending upward from the chafer rubber has a 100% modulus of 10 to 45 kg / cm ² of the outer rubber, the outer rubber forms a carcass in the sidewall portion which is most deformed when the tire is deformed. It is possible to follow and expand and contract, prevent its separation, and prevent stress from propagating to the bead portion. Moreover, by dividing the outer rubber in this way, it is possible to adopt different rubber compositions having different physical properties for both the chafer rubber and the sidewall rubber, thereby expanding the freedom of design and improving the overall tire durability. Can be measured.

[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 showing a tire cross section in a normal internal pressure state in which a normal internal pressure is applied to the normal rim R, a high speed heavy load tire 1 (hereinafter referred to as tire 1) is
It is provided with a bead portion 3 through which the bead core 2 passes, a sidewall portion 4 which is continuous with the bead portion 3 and extends upward in the tire radial direction, and a tread portion 5 which joins between the upper ends thereof.

Further, in the tire 1, the bead core 2 is folded from the inner side of the tire to the outer side, and the inner layer 7A is composed of a plurality of inner plies, for example, four inner plies. A carcass 7 having a plurality of, for example, two outer layers 7B made of outer plies to be wound is provided.

The inner layer 7A has folded portions 71 at which the bead core 2 is folded from the tire inner side to the outer side at both ends of the toroidal main body portion 70 passing through the side wall 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 part 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. Further, in the bead portion 3, a side packing rubber 15 having a small thickness 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 having a thickness gradually reduced above and below a central portion 15A having a maximum thickness t in this embodiment.
The crescent shape is formed by extending B and 15C.

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

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 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 sandwiching the tire equator and 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 total width W of the tire, preferably 70 to 7
It ends at a position 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
Low-stretch elastic cords are 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 is provided on the outer surface of the belt layer 10 to enhance cut resistance.

In the present invention, the outer rubber 1
7 from the bottom surface of the bead portion 3 to the sidewall rubber 1
5 and 200 of the normal internal pressure state and the normal load.
%, A chafer rubber 20 that extends upward in the tire radial direction including a contact area Y that contacts the flange Ra of the regular rim R in a 200% load state and a sidewall rubber 21 above the chafer rubber 20. .. Moreover, the 100% modulus MP of the side packing rubber 15 is 53 to 95 kg / cm ² , and the 100% modulus MA of the bead apex rubber 9 is 78 to 120 kg / c.
m ² , 100% modulus M of the chafer rubber 20
C is 40 to 70 kg / cm ² and the side wall rubber 2
100% modulus MS of 1 is 10 to 45 kg / cm ² , while each modulus MP, MA, MC, MS is MS <
MC <MP <MA.

Also, bead apex rubber 9, side pad
King rubber 15, chafer rubber 20, side wall
Rubber The 100% modulus of 21, the elongation at break
(%), Stress at break (kg / cm2), carcass
Shown in Table 1 together with the numerical values of the 7 topping rubbers.
You

[0027]

[Table 1]

Like this Bead apex rubber 9
High hardness with 100% modulus of 78-120 kg / cm2
The rubber is used. This increases the rigidity of the bead section.
Therefore, the bead deformation amount h0-h1 is reduced. Jijiru More chefs
100% modulus as rubber 20 is 40 to 70 kg /
cm2 relatively Use a soft one and 1
00% modulus is 53 ~ 95kg / cm2,
Is smaller than bead apex rubber 9 and chafer
Insert a side packing rubber 15 that is larger than the rubber 20.
Let This increases rigidity and reduces rigidity steps
And shear stress are alleviated to improve the durability of the bead It Moreover,
Chafer rubber 20 has at least 100% modulus
Since it is 40 kg / cm2 or more, it is
External damage such as rim displacement can be suppressed. Like this, bee
Effect of reducing bending stress and deformation heat by reducing the amount of deformation
Phase of effect of relaxation of shear stress and effect of suppressing external damage
By the riding action, bead damage can be greatly suppressed.

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. 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 is because in order to increase the bending rigidity of 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, and Side packing rubber 1 than this 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 the height HP 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. 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. However, when the height HC is excessively increased, the following capability of the sidewall portion 4 for tire deformation is deteriorated, and therefore the difference HC-HP between the height HC and the height HP is equal to the thickness of the chafer rubber 20. It is preferable to set it to 0.5 times or more and 2.5 times or less.

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 forming the 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 in the tire axially outward direction in multiple steps.

(Specific Example) As shown in Table 2, an aircraft tire having the tire structure shown in FIG. 1 and a tire size of 46 × 17R20 is made of bead apex rubber, side packing rubber, chafer rubber, and sidewall rubber. A 100% modulus was changed, and a trial tire was produced along with a comparative example.
The result of repeatedly measuring the bead durability under the condition of taxi simulation (load 100%) based on C62c is shown in the table by an index with Example as 100. It is preferable that the index is large, and it can be seen that the products of Examples have excellent bead portion durability.

[0036]

[Table 2]

Further, the example product is
Under the above conditions, the bead temperature was low by about 5 ° C. and the bead deformation amount was reduced by about 1 to 1.5%.

Furthermore, after running the tires of the examples, visual inspections showed no external damage such as rim chafing and cracks.

[0039]

As described above, the high-speed heavy-duty tire of the present invention can prevent bead deformation, bead heat generation, and external damage such as rim chafing without changing the tire internal structure and without lowering running performance. It can be effectively suppressed and the bead durability can be greatly improved.

[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.

FIG. 3 is a schematic diagram showing a bending deformation state of a bead portion.

FIG. 4 is a diagram showing a relationship between bead outer surface heights h0 and h1 and a bead portion temperature.

[Explanation of symbols]

 2 bead core 3 bead part 3B bead bottom 4 sidewall part 5 tread part 7 carcass 9 bead apex rubber 10 belt layer 15 side packing rubber 16 sidewall rubber 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 folded around the bead core, an upper side of the carcass in a radial direction of a tire 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 tire is mounted on the regular rim and covers the packing rubber, and is filled with the regular internal pressure as well as the regular load. The tire includes a chafer rubber that extends upward in the tire radial direction including a contact region that comes into contact with the flange portion of the regular rim in a 200% load state in which a 200% load is applied, and a sidewall rubber that extends upward from the chafer rubber in the radial direction of the tire. In addition, the modulus MP at 100% elongation of the side packing rubber is 53 to 95 kg / cm ² , and the modulus of the bead apex rubber is 1
Modulus MA at 00% elongation is 78-120kg / c
m ² , the modulus MC of the chafer rubber at 100% extension is 40 to 70 kg / cm ^2, and the modulus MS of the sidewall rubber at 100% extension is 10 to 45 kg /
cm ² , and above each modulus MP, MA, MC, MS
High-speed heavy-duty tire with MS <MC <MP <MA. 2. The side packing rubber has a height HP at the upper end in the radial direction from the bead bottom surface that is larger than the height HA from the bead bottom surface at the upper end of the bead apex rubber and is 1/1 / the tire cross-section height H. Smaller than 2 and
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.