JPH04189608A - Tire for high speed and heavy load - Google Patents

Abstract

PURPOSE:To effectively ease the shearing force between a carcass body and a folding section and improve the bead durability of a tire by providing a bead filler having an internal piece Which intervenes between the carcass body and folding, section and ends between the upper end of the folding section and the tire maximal width point. CONSTITUTION:The bead section 3 of a tire for high speed and heavy load for an aircraft is provided with a bead filler 10, which wraps the periphery of a bead evepques 9 together with a bead core 2 in a body. This bead filler 10 is formed so as to have an internal piece 12 arranged along the inside surface of the bead evepques 9, bottom piece 13 arranged along the bottom surface of a bead core 2 and external piece 14 arranged along the external surface of the evepques 9 from at least one reinforcing ply 10A to which a reinforcing cord using organic fiber such as aromatic polyamide is arranged at angle of the range from 70 deg. to 90 deg. to the peripheral direction of the tire. The upper side 12a of the internal peace 12 is extended in the upper direction in the radial direction over the upper end 71a of the folding section 71 of a carcass 7 and in the lower direction of the tire maximal width point Q2 of a side wall 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a high-speed, heavy-load tire that can improve the durability of a bead portion and can be particularly suitably used as an aircraft tire.

[Conventional technology]

High-speed, heavy-duty tires, especially tires used for aircraft, have increased in size and flight speed in recent years, resulting in increased speeds and loads during takeoff and landing. The amount of deflection in the radial direction of the tire is set relatively large, for example, about 28 to 35%.

Therefore, for safe takeoff and landing, aircraft tires must withstand such repeated large deformations, large loads, and high speeds.

On the other hand, as such aircraft tires, those having a cross-brie structure in which the carcass cords intersect with each other between braises are often used.

However, this type of tread has low tread rigidity and high weight, which makes it unfavorable in terms of wear resistance, heat generation, etc., and there are limits to its use due to the remarkable performance improvements of large jet aircraft in recent years.

Therefore, in recent years, radial tires in which carcass cords are arranged radially and a strong belt layer is wrapped around the outside of the carcass are being used.

[Problem to be solved by the invention]

However, as the service life of such radial structure aircraft tires increases, it has been found that the durability of the bead portion in particular is relatively low compared to the durability of the tire as a whole.

Note that this is because the amount of deflection in the tire radial direction is 2 as described above.
This is thought to be due to the fact that they are dogs, accounting for approximately 8 to 35% of cases. That is, as shown in Fig. 4, a large tensile stress F is generated in the carcass case A under load, and this stress acts in a spiral manner around the bead core B, so that the carcass main body part A1 and the carcass folded part A2 are significantly increases the shear force between Further, when the bead portion C is deformed, the bead portion C greatly protrudes to the outside of the tire, and a compressive force acts on the outer side and a tensile force acts on the inner side, which promotes an increase in the shearing force. It is presumed that this causes cord loosening to progress starting from the upper end of the folded portion A2, thereby inducing bead damage.

Conventionally, in order to reduce the amount of deformation of the bead, the bead apex has been made thicker and taller, but this increases the internal temperature due to the increased volume of the bead, which causes adverse effects. This tends to impair bead durability.

The present invention is based on interposing a bead filler between the main body part and the folded part of the carcass, so that the shearing force can be alleviated without increasing the volume of the bead part, and the bead durability can be improved. The aim is to provide tires for heavy loads.

[Means to solve the problem]

In order to solve the above object, the high speed heavy load tire of the present invention has a toroidal main body part which extends from the tread part through the sidewall part to the bead core of the bead part, and a toroidal body part which extends from the main body part and extends around the bead core. a carcass having a folded part folded back from the inside to the outside and having carcass cords arranged radially; a belt layer disposed above the carcass in the radial direction and inside the tread; and above the bead core and the main body of the carcass. a bead apex extending upward in the tire radial direction between the folded portion and the folded portion;
An outer piece consisting of reinforcing cords arranged at an angle of ~90° and extending from the inner piece along the axially inner side of the bead apex to the bottom piece along the bottom side of the bead core to the outer side of the bead apex. The upper end of the inner piece of the bead filler is located above the upper end of the folded part of the carcass in the tire radial direction and below the tire maximum width point of the sidewall part, and the upper end of the outer piece of the bead filler is 1/1/2 of the bead apex length, which is the length in the tire radial direction from the upper edge of the bead core to the upper end of the bead apex.
The double length is located below the center height position of the bead apex, which is spaced from the upper edge, in the tire radial direction.

[Effect]

In the bead filler of a high-speed, heavy-duty tire constructed in this way, the inner piece along the outer surface of the bead apex extends upward beyond the upper end of the folded part of the carcass, thereby creating a gap between the folded part and the main body of the carcass. May intervene. In addition, since the inner piece is discontinued below the maximum midpoint of the tire, the tensile stress that acts upon the tire during deformation is extremely small compared to the main body of the carcass. The shear force between the parts can be effectively alleviated. As a result, cord looseness from the upper end of the folded portion can be suppressed.

Furthermore, since the bead filler wraps the bead apex together with the bead core by the inner piece, bottom piece, and outer piece, the bead rigidity can be improved without increasing the volume of the bead part, and the amount of deformation of the bead part can be reduced.

〔Example〕

Below, one embodiment of the present invention is tire size 46×17R20.
This will be explained based on the drawings, taking as an example the case of an aircraft tire.

In FIG. 1, which shows a cross section of the tire in a normal internal pressure state when it is mounted on a normal rim R and a normal internal pressure is applied, a high-speed heavy load tire (hereinafter referred to as tire 1) has a bead portion 3 through which a bead core 2 passes, and the bead portion. 3 and extending upward in the tire radial direction, and a tread part 5 connecting the upper ends of the sidewall part 4.

In addition, in this example, a bead core 2 is provided between the bead portions 3 and 3.
an inner layer 7A consisting of a plurality of inner plies, for example four inner plies, which are folded from the inside to the outside of the tire, and a plurality of inner plies, for example two outer plies, surrounding the folded part 71 of the inner layer 7A and folded from the outside to the inside of the tire. The carcass 7 having an outer layer 7B consisting of

The inner layer 7A has folded parts 71 for folding the bead core 2 from the inside of the tire to the outside, at both ends of a toroidal main body part 70 extending from the tread part 5 through the sidewall part 4 to the bead part 3 along the inner cavity of the tire. In addition, the outer layer 7B extends from the main body part 73 arranged outside the main body part 70 to a rolled-up part 74 which wraps around the folded part 71 by being folded back from the outside of the bead core 2 to the inside.

In this example, a carcass cord 8 made of organic fiber cord is used for the inner and outer briers, and the carcass cord has a diameter of 70 to 90 in the tire circumferential direction.
arranged in a radial direction with an inclination of
In this example, the carcass cords alternately intersect and are inclined in the circumferential direction between the inner and outer plies adjacent to each other. Note that rayon, polyester, vinylon, nylon, aromatic polyamide, etc. can be used as the organic fiber cord.

Further, a belt layer 15 is wound on the upper side of the carcass 7 in the tire circumferential direction.

The belt layer 15 is a multilayer body made up of a plurality of belt plies 15A, for example, eight belt plies 15A, and the outer ends thereof are aligned with a slope along the outer surface of the tire. The belt layer 15 has a belt width of about 70 to 85% of the cross section of the tire, and restrains the carcass 7 with a hoop effect, thereby increasing tire rigidity and improving running performance.

Note that the belt cords forming the belt brace 15A are arranged side by side and inclined at an angle of 0 to 30 degrees with respect to the tire equator.

Moreover, the main body part 70 and the folded part 7 of the inner layer 7A of the carcass 7
A bead apex 9 is disposed above the bead core 2 and extends upward in the radial direction in a tapered shape.

Bead Apex 9 has a JISA hardness of 65.
A relatively hard rubber of ~95° is preferably used.

In this embodiment, the bead core 2 is moved from the bead heel point Q1, which is the point where the extension line of the rim base Rb and the extension line of the inner surface of the rim flange Ra intersect, as shown in FIG.
The distance X in the tire axial direction from the bead core 2 to the inner edge in the tire axial direction, and the rim flange R from the bead heel point Q1
The ratio X/H to the flange height H, which is the distance in the tire radial direction to the upper end of a, is set to be 0.8 or more and 1.05 or less.

Furthermore, the upper edge of the bead core 2 in the tire radial direction is located below the upper end of the rim flange Ra, and the ratio Y of the radial distance Y from the upper end of the rim flange Ra to the upper edge of the bead core 2 and the flange height H is /H is 0 or more and 0
．． It is set at 3 or less.

Further, a rubber thickness Fl that is arranged on the outside of the carcass 7 and forms the tire outer skin at a reference point Q3 that is spaced upward in the tire radial direction from the bead heel point Q1 at a distance of 0.2 times the tire cross-sectional height HO; While the ratio Fl/X to the distance X is greater than O and 0.20 or less, the carcass 7
Total tire thickness F including
2 and the distance X is set to be larger than the ratio Fl/X and 0.60 or less.

Note that these values are intended to reduce the amount of bead deformation by forming the shape of the bead apex 9 in advance into a shape close to the loaded shape.

In other words, when a high-speed heavy load tire such as an aircraft radial tire receives a load, the bead portion 3 bends and deforms in the tire cross section in the radial direction above the straight line L1 drawn in the tire axial direction at the upper end of the rim flange Ra. arises,
By repeating this deformation, mainly the rubber of the bead apex 9 generates heat. Therefore, by forming the bead apex 9 in advance in a shape close to the deformed state due to load, it is possible to reduce the deformation heat generation of the bead apex 9, and for this purpose, each value of the ratios X/H and Y/H can be reduced. is regulated.

Note that the bead apex 9 includes the inner layer 7A from the bead core 2.
While filling the space between the main body part 70 and the folded part 71,
Since it extends toward the central height position of the sidewall portion 4, which is the minimum position of bending rigidity, its shape is roughly determined by the relative position of the bead core 2 and the rim R, and therefore the ratio X/H1Y/H is By setting within this range, it is possible to approximate a load shape in which the bead apex 9 bends outward. Note that when the ratio X/H is less than 0.80 and the ratio Y/
When H is greater than 0.30, the rising angle of the bead apex 9 becomes large, increasing the amount of bead deformation. Mata ratio X/
When H exceeds 1.05, the volume of the bead portion 3 becomes excessive, which adversely affects durability and rim fitability. Therefore, the ratio X/H is more preferably 0.85 or more and 1.0 or less. Also, when the ratio Y/H is less than 0, bead core 2
The upper edge is radially above the straight line L1, and the bending of the carcass 7 is concentrated on the upper edge of the bead core 2, causing destruction of the carcass 7 itself. Note that the center height position of the sidewall portion 4 and the bead heel point Q1 are determined by the tire size and rim size. Further, the bead core 2 can have a hexagonal shape, a quadrangular shape, etc. in addition to a circular cross section.

Further, the folded portion 71 of the carcass 7 extends along the outer surface of the bead apex 9, and the inner brais are arranged such that the folded ends of the inner braais are gradually lowered toward the outside in the axial direction of the tire. It is terminated. Among them, the height Hl of the lowest folded end is located above the upper end of the bead apex 9. In other words, the height F2 of the bead apex 9 from the bead heel point Q1
is set higher than the flange height H and lower than the lowest folded end height Hl of the inner layer 7A. Moreover, the folded portion 71 has an inner layer 7A in its upper portion.
An overlapping region G extending parallel to and overlapping with the main body portion 70 of
is formed.

In the present invention, the bead portion 3 is provided with a bead filler 10 that integrally wraps around the bead apex 9 together with the bead core 2, thereby reinforcing the bead portion 3 and increasing the bead rigidity.
The shearing force between the folded portion 71 and the folded portion 71 is alleviated.

The bead filler 10 includes at least one reinforcing cord 11 made of organic fiber such as rayon, polyester, vinylon, nylon, aromatic polyamide, etc., arranged at an angle of 70 degrees or more and 90 degrees or less with respect to the tire circumferential direction. In the example, it is formed from one reinforcing ply 10A, and the reinforcing cord 11 preferably has a strength at least equal to or greater than the carcass cord 8.

The bead filler 10 has an inner piece 12 along the inner surface of the bead apex 9, a bottom piece 13 along the bottom surface of the bead core 2, and an outer piece 14 along the outer surface of the bead apex 9, and is wound into a substantially U-shape. By wrapping and integrating the bead apex 9 with the bead core 2, the lateral rigidity of the bead portion is strengthened and the amount of bead deformation is reduced.

Moreover, the upper side 12a of the inner piece 12 extends upward in the radial direction beyond the upper end 71a of the folded part 71 of the carcass 7 and below the tire maximum midpoint Q2 of the sidewall part 4, so that the upper side 12a of the inner piece 12 are located adjacent to both the main body portion 70 and the folded portion 71 in the overlapping region G.

Here, since the upper end 12a of the upper piece 12 is interrupted below the tire maximum width point Q2 as described above, the tensile stress that acts during tire deformation is applied to the main body portion 70 of the carcass 7.
It is extremely small compared to the tensile stress acting on the main body portion 70 and the folded portion 71, and can therefore act as a neutral presence in the stress acting on the main body portion 70 and the folded portion 71, and can effectively alleviate the shearing force between them. Note that when the upper end 12a is interrupted above the tire maximum width point Q2, the tensile stress on the upper piece 12 increases, and the shearing force between the upper piece 12 and the folded portion 71 increases.

Furthermore, in this example, in order to further enhance the shearing force mitigation effect, as shown in FIG. Both the inter-cord distance t1 in the right angle direction and the inter-cord distance t2 between the reinforcing cord 11 and the carcass cord 8 of the folded portion 71 adjacent thereto are each set to 1 of the diameter of the carcass cord 8.
/ 4 times or more and 2 times or less. If the inter-cord distances t1 and t2 are each smaller than 1/4, the stress relaxation effect of the rubber interposed between the cords will be poor, and if it exceeds 2D, the thickness of the bead portion will increase, leading to an increase in internal temperature. This results in a decrease in bead durability. According to the inventors' consideration, as mentioned above, at the reference point Q3, which is located upward in the tire radial direction from the bead heel point Q1 at a distance of 0.2 times the tire cross-sectional height HO, on the outside of the carcass 7. The ratio Fl/X of the rubber thickness Fl forming the outer skin of the tire arranged and the distance
It has been found that by setting the ratio F2/X of 2 and the distance By setting the inter-cord distances t1 and t2,
This can be achieved.

On the other hand, filler rubber 17 covering the reinforcing cord 11
It is necessary to expand and contract along with the carcass rubber 18 covering the carcass cord 8 following each cord, and therefore,
It is preferable to use a rubber that has excellent adhesion to the carcass rubber 18, that is, a rubber composition that is almost the same as the carcass rubber 18, and whose 100% modulus is 0.6 times or more the 100% modulus of the carcass rubber 18 and 1.3
It is better to set the value to less than twice that. Naori-casu rubber 18 usually has a 100% modulus of 30 to 100 kg/d,
Therefore, it is preferable that the filler rubber 17 exhibits a 100% modulus of about 18 to 130 kg/cd.

Further, the bead filler 10 has an upper end 14a of the outer piece 14.
from the upper edge of the bead core 2 to the bead apex 9
It is located at a position separated by 1/2 the length of the bead apex, which is the tire radial length up to the upper end, that is, below the center height position h3 of the bead apex 9 in the tire radial direction. Note that the area from the center height position h1 to the lower edge of the bead core 2 has high rigidity.
and rim flange Ra, it is a stable region that is hardly affected by bead deformation. Therefore, by terminating the upper end 14a of the outer piece 14 within this region, the distance between the cords from the upper end 14a can be reduced. new outbreaks are being prevented.

〔Concrete example〕

The tire structure is shown in Figure 1, and the tire size is 46x1.
7R20 aircraft tires were prototyped based on the specifications shown in Table 1, and the durability of each of the prototype tires at the bead portion was measured. Note that Table 2 shows the specifications and physical properties of the carcass cord, belt cord, and reinforcement cord listed in Table 1.

In addition, as a durability test, the US Federal Aviation Administration standard TSo-C
The bead damage was compared by running continuously for up to 3,000 km at a running speed of 11 km/h under a standard load based on 62c, that is, a 120% load state. As shown in Table 1, it can be seen that the tires of the examples of the present invention have significantly improved bead durability.

〔Effect of the invention〕

As described above, the high speed heavy load tire of the present invention is provided with a bead filler having an inner piece interposed between the main body of the carcass and the folded part and terminating between the upper end of the folded part and the maximum width point of the tire. Therefore, the shearing force between the main body part and the folded part can be effectively alleviated, and the bead durability can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view showing a bead portion, Fig. 3 is a sectional view illustrating the distance between cords, and Fig. 4 is a sectional view explaining the prior art. FIG. 2--Bead core, 3--Bead part, 4
, side wall part, 5 , , , , h reflex 1 part, 7-carcass, 8-carcass cord, 9
...Bead Apex, 10...Bead Filler, 111.・, Reinforcement cord, 12. -,,,,
, inner piece, 13. ,,,,,bottom piece, 14...outer piece, 15...belt layer. Patent Claimant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura Figure 3 4111 At(A) ＼

Claims (1)

[Scope of Claims] 1. A toroidal main body section extending from the tread section through the sidewall section to the bead core of the bead section, and a folded section continuous to the main body section and folded back from the inside of the tire to the outside around the bead core. a carcass having carcass cords arranged in a radial manner; a belt layer disposed above the carcass in the radial direction and inside the tread; The bead portion has a bead apex extending upward in the tire circumferential direction.
An outer piece consisting of reinforcing cords arranged at an angle of ~90° and extending from the inner piece along the inner side of the bead apex in the tire axial direction to the bottom piece along the bottom side of the bead core to the outer side of the bead apex. The upper end of the inner piece of the bead filler is located above the upper end of the folded part of the carcass in the tire radial direction and below the tire maximum width point of the sidewall part, and the upper end of the outer piece of the bead filler is 1/1/2 of the bead apex length, which is the length in the tire radial direction from the upper edge of the bead core to the upper end of the bead apex.
A high-speed, heavy-load tire having a length twice as long as the center height of the bead apex separated from the upper edge in the tire radial direction. 2. The bead filler has a distance between the reinforcing cord and the carcass cord of the carcass along which the bead filler runs, in a direction orthogonal to the bead filler, which is at least 1/4 times the diameter of the carcass cord and 2.0. The high-speed heavy load tire according to claim 1, characterized in that the tire is less than twice as large.