JPH05270211A - Radial tire for aircraft - Google Patents

Abstract

PURPOSE:To prevent eccentric wear such as off-shouldering without impairing the running performance required of an aircraft tire. CONSTITUTION:A radial tire for aircraft includes a carcass 6 and a belt layer 7, the latter being formed by laying a belt cord 11 or cords in parallel and lining them with rubber to produce a band-shaped element 10, which is positioned aslant to the tire equatorial plane and folded angle-shapedly in alternation at folding points in contact with the two side edges F1, F2 of this layer 7 so as to go for the whole circumference, wherein the inclination angle of the band-shaped element 10 intersecting the tire equator is made between 5-25 deg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire for aircraft having improved wear resistance, particularly uneven wear resistance in the tread shoulder region, without deteriorating the running performance of the tire.

[0002]

2. Description of the Related Art Aircraft tires have recently been increased in operating speed and operating load as the size of aircraft has increased and flight speed has increased.

In order to effectively mitigate the impact when the aircraft takes off and landing on the runway, the amount of flexure of the tire under load is extremely large, for example, 28 to 38%, so that it can withstand large cyclic deformation.

With the increase in speed of airplanes, the speed associated with takeoff and landing is increasing, so that it must withstand high-speed rotation under large load and large deformation.

In order to reduce the weight of an airplane, a burden load of about 130 to 360 times (about 50 times for a normal tire) acts on the tire unit weight, and for that reason, it is extremely ^high such as 10 to 18 kg / cm ^2. High internal pressure is applied.

In addition, although the speed of movement between the runway and the gate is low, it is required to withstand a taxi condition in which a large load acts for a relatively long time.

Further, since an airplane often makes a turn to change the direction of the airplane when it runs between the runway and the gate, it has the above-mentioned durability and prevents the runout at the time of turning and stabilizes the operation. It is necessary to increase the cornering force to improve the property. Further, such an improvement in steering stability is also useful for preventing rolling, swinging, etc. during takeoff and landing.

On the other hand, as a tire for aircraft, a cross-ply structure in which carcass cords are arranged so as to intersect each other is often used. But this one
Since the carcass cords intersect at a relatively large angle, the lateral rigidity is great and the steering characteristics are also relatively excellent, but the rigidity of the tread part is small and the weight is large. However, it is not preferable in other properties such as wear resistance and heat generation property, and the use of the cross-ply structure is being restricted due to the remarkable improvement in performance of large jet aircraft in recent years.

Therefore, in recent years, a plurality of breaker plies are arranged radially outward of a so-called radial or semi-radial structure carcass ply in which carcass cords are arranged substantially at right angles to the tire equator, Radial tires having a belt layer formed by stacking a plurality of belt plies in which belt cords that are substantially parallel to the tire equator are arranged side by side are being used.

[0010]

[0011]

However, in a tire having such a belt layer, there is a problem that the tread shoulder region is rapidly worn when the tire rolls. The tire t bends and deforms at the ground contact portion s as shown in FIG. 9 during load rolling. However, when the belt layer is formed by laminating a plurality of belt plies, the bending deformation of the belt layer causes The vicinity of the center in the thickness direction is defined as the neutral surface l, and the larger the distance from the neutral surface 1 to the inner side in the tire radial direction, the larger the tensile stress FA is received. On the other hand, the larger the distance from the neutral surface toward the outer side in the radial direction, the larger the compressive stress FB will be received.

However, depending on the setting of the inclination angle of the belt cord, it is difficult to extend in the tire circumferential direction, that is, when the ply having the belt cord substantially parallel to the tire equator is arranged inside the tire radial direction. The expansion and contraction of the belt layer itself is significantly hindered. As a result, the elastic elongation of the belt layer alone cannot absorb the difference in circumferential length between the central region of the tread portion and the tread shoulder region based on the radius of curvature which is an arc in the meridional section of the tread surface at the time of contact with the ground. For this reason, the tread rubber in the tread shoulder region, when landing, increases the circumferential shear deformation between the start of stepping and the start of kicking, which increases the shear deformation in the circumferential direction. When kicked out, the tread rubber is removed from the tread rubber all at once, so that the tread rubber in the tread shoulder region slips between the tread rubber and the road surface, which causes so-called shoulder drop wear.

As a result of earnest research to reduce the occurrence of uneven wear while maintaining various running performances as an aircraft tire, the inventor has used a belt-shaped body in which a belt cord intervenes in a belt layer, and the belt-shaped body is broken. By increasing the rigidity of the side edge part of the belt layer by repeatedly forming it in a letter shape,
It was found that the above-mentioned uneven wear can be prevented.

It is an object of the present invention to provide a radial tire for an aircraft which can prevent uneven wear, especially shoulder wear without lowering various running performances and can improve durability.

[0015]

SUMMARY OF THE INVENTION The present invention is directed to a carcass consisting of a carcass ply in which a tread portion passes through a sidewall portion and is folded back around a bead core of a bead portion and carcass cords of a radial arrangement are juxtaposed, and a tread portion of a tread portion. A radial tire for an aircraft, comprising a belt layer arranged inside and on a radially outer side of a carcass, wherein the belt layer is a tire in which one or a plurality of belt cords are aligned in parallel and are rubberized. The belt-shaped body is formed by alternately folding back and forth in a V shape at a turning point that is inclined with respect to the equator and is in contact with both side edges of the belt layer, and the belt-shaped body is an inclination angle intersecting with the tire equator on the tire equator. A radial tire for an aircraft, wherein θ is set to 5 ° or more and 25 ° or less.

[0016]

The belt layer is formed by wrapping a belt-shaped band made of rubber on a belt cord and continuously wrapping the band at both side edges of the belt layer. It is possible to prevent the peeling at the side edge as when using a ply and improve the durability.

Moreover, since the belt-like member is bent in a V shape in the plane of the belt-like member, it is possible to prevent non-uniform stress from being generated inside the belt layer due to the reaction force of the belt cord caused by the folding. The durability of the tire can be further improved.

Further, on the tire equator, the belt-like body has an inclination angle θ intersecting with the tire equator of 5 ° or more and 25 ° or less.

In a radial tire with a normal internal pressure applied, assuming that no belt layer is present, the carcass bridged between the bead cores has a circular cross section due to the internal pressure. A characteristic of radial tires is that they are fastened with a belt layer to maintain their shape. Further, the higher the speed and the higher the load, the higher the internal pressure is set, so that the tightening force of the belt layer must be increased in order to suppress the expansion of the carcass. For this purpose, it is necessary to set the inclination angle θ of the strip to 25 ° or less. On the other hand, the tread surface is formed as an arc in the tire axial cross section, and a difference in circumferential length occurs between the central region of the tread portion and the tread shoulder region based on this arc. If the inclination angle θ of the strip is small,
At the time of landing, as a result of the expansion and contraction of the belt layer being hindered, the difference in circumferential length in the tread portion cannot be absorbed, and the rubber in the tread shoulder area accumulates the difference in circumferential length between the start of stepping and the start of kicking. The shear deformation in the circumferential direction increases, but this shear deformation is temporarily removed from the tread rubber at the time of kicking, so that the tread rubber in the tread shoulder area at the time of kicking is It is not possible to prevent the occurrence of uneven wear in the tread shoulder region due to slippage between the two. Therefore, the inclination angle is set to 5 ° or more to facilitate the expansion and contraction of the belt layer in the tire axial direction.

Based on such a technical idea, in the present application, the inclination angle θ is set to 5 ° or more and 25 ° or less. In order to achieve the above purpose, the tilt angle θ is set to 1
It is preferably in the range of 0 ° to 20 °.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Referring to FIG. 1, which shows a cross section of a tire mounted on a regular rim R and in a regular internal pressure state in which a regular internal pressure is applied, a radial tire 1 for an aircraft extends from a tread portion 2 and both ends of the tread portion 2 inward in the tire radial direction. It is provided with sidewall portions 3 and 3 and bead portions 4 and 4 which are continuous with the sidewall portion 3 and through which a bead core 5 passes.

Further, in the radial tire 1 for an aircraft, both ends of the tread portion 2 pass through the sidewall portion 3 and are folded back around the bead core 5 of the bead portion 4, and a belt is provided outwardly in the radial direction thereof. The layer 7 is wound in the tire circumferential direction. Further, a reinforcement fabric 17 using a protective cord is arranged outside the belt layer 7.

In the present embodiment, the carcass 6 is an inner layer 6A composed of a plurality of carcass plies 6a ...
And a plurality of, for example, two, outer carcass plies 6 surrounding the folded-back portion of the inner layer 6A and wound inward from the outside of the tire.
and an outer layer 6B made of b.

The inner and outer carcass plies 6a and 6b each have a carcass cord 15 of a radial or semi-radial arrangement inclined at an angle of 70 to 90 ° with respect to the tire equator C. Between the carcass plies that overlap with each other, the carcass cords are stacked in different directions so that the carcass cords alternately intersect and incline with respect to the circumferential direction.

In the present embodiment, the bead portion 3 is provided with a bead apex 8 which rises radially outward from the bead core 2 through a space between the main body portion and the folded portion. Reinforce the wall 3.

The belt layer 7 is composed of a continuous breaker layer in which the strip 10 is continuously wound in a zigzag shape. As shown in FIG. 3, the strip-shaped body 10 has one or more and 1 arranged in parallel.
0 or less, and in the present embodiment, it is an elongated body formed by rubberizing three belt cords 11 with rubber 12 and having a substantially rectangular cross section and a small width. The width W of the band
It is preferable that o be 5 to 15 mm.

As the belt cord 11, an organic fiber such as nylon, polyester or aromatic polyamide, a steel cord or the like is used. The aromatic polyamide fiber has strength substantially equivalent to that of steel and is highly flexible, and thus can be suitably used.

In the present embodiment, the continuous breaker layer uses one strip 10 as shown in FIG.
Is inclined at an angle of θ with respect to the tire equator C, and is bent alternately in the plane of the strip 10 at the turning points B1 and B2 contacting at both side edges F1 and F2 of the belt layer 6. By returning it, it makes a zigzag shape and circulates in the tire circumferential direction.

As a result of the circulation, the belt-shaped body 10 makes one round in the tire circumferential direction as shown in FIG. 5 and returns to the position adjacent to the starting end point S, and the end surfaces 10a, 10a of the belt-shaped body facing each other.
Are made to abut each other and are turned around at both side edges F1 and F2 of the belt layer 7 in the same manner as in the first round, and are made to go around in the second round. In this way, the belt-shaped body 10 orbits with the circumferential pitch P, which is the folded length of the belt-shaped body 10, being displaced in the tire circumferential direction.

Further, in the present embodiment, the belt-shaped body 10 is formed with the product PN of the circumferential pitch P and the number of turns N at any one of the side edges F1 (F2) as the circumferential length of the belt layer 7. Is doing. Therefore, by rotating the belt-shaped body 10 a plurality of times by using the above-described method, the belt-shaped body 1 is spaced between the circumferential pitches P.
Filled with 0s. The strip 10 is bent in a zigzag shape, and two continuous breaker layers in which the inclination angle θ of the strip 10 is reversed are formed in the inner and outer layers. By repeating the above method, a continuous breaker layer composed of three or more layers can be formed.

Here, the number of turns n of the strip 10 is the belt layer 7
The following relationship is established with the width W of the tire in the axial direction, the inclination angle θ, and the width Wo of the belt-shaped body 10.

The circumferential pitch P is Wo / sin θ between the width Wo of the strip 10 and the repeating pitch Pt of the strip 10 in the first round is Pt = P × n and Wcot θ = Pt− P / 2 = P (n-1) / 2 Therefore, cot θ = P (n-1) / 2W ...... When the equations are combined with each other, cot θ = {Wo / sin α (n-1) } / 2W = Wo (n-1) / 2W sin θ ... Further, since cot θ = cos θ / sin θ, the equation can be modified as follows. cos θ = Wo (n-1) / 2W ... Therefore, n-1 = 2Wcos θ / Wo ... Therefore, n is n = (2Wcos θ / Wo) +1.

The belt width and the inclination angle θ are values determined from the functional aspect of the tire, and the belt W is rotated by determining the width Wo of the belt 10 and the number of turns n of the belt so as to satisfy the above expression. The belt layer 7 can be formed without forming a gap between the strip-shaped bodies 10, and the end of the strip-shaped body 10 can be brought into abutment with the starting end S of the strip-shaped body 10. By circling the belt-shaped body 10 in this manner, the belt cords 11 are arranged in series without being divided.

Here, as shown in FIG. 3, the belt-like body 10 has an opening angle α at one of the side edges F1 (F2), which is centered on the tire axis L sandwiching the turning points adjacent in the circumferential direction. When one strip 10 is sequentially displaced and circulated as described above, the opening angle α1 is a value obtained by subtracting the displacement of the strip 10 from 360 °, that is, a value slightly below 360 °. In addition, the unfolded length of the belt layer 7 in the circumferential direction is 30
When the belt width of 00 mm is 300 mm, the inclination angle θ1 of the belt 10 with respect to the tire equator C is about 5 °.

Further, as shown in FIG. 8, when the belt-shaped body 10 is folded back approximately every half circumference, that is, at a pitch of approximately 180 °, the inclination angle θ2 is approximately 15 to 18 ° although the belt width changes.
It becomes the range of.

The strips 10 are adjacent strips 1
The end faces 10a and 10a may be arranged so as to slightly overlap with each other between 0 and 10, and as shown in FIG. 6, a plurality of, for example, three strips 10 ... This can be formed by folding back the pushing points B1 (B2) at the immediate edges F1 (F2) of the strips 10 ...

Further, as shown in FIG. 7, it is possible to form a belt layer 6 by arranging a plurality of strips having different widths, for example, two strips 10A and 10B side by side and folding back in a V shape.

Between the folding points B1 and B2 on one side of the belt ply, the belt-shaped body may be linearly arranged as shown in FIG. 2 or may be formed by a curve such as a sine curve. The present invention can be modified into various aspects.

[0039]

INDUSTRIAL APPLICABILITY As described above, the radial tire for an aircraft of the present invention is characterized in that the belt layer is formed by folding the belt-shaped rubber band-shaped member into a doglegged shape so as to circulate. It is possible to prevent uneven wear such as shoulder drop wear and improve durability without lowering performance.

[Brief description of drawings]

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

FIG. 2 is a developed plan view illustrating the configuration of the carcass and the belt layer.

FIG. 3 is a perspective view showing an example of the circulation of the strip.

FIG. 4 is a perspective view showing an example of a band-shaped body.

FIG. 5 is a plan view schematically showing folding of the band-shaped body.

FIG. 6 is a plan view showing another example of the winding of the strip.

FIG. 7 is a plan view showing another example of the circulation of the strip.

FIG. 8 is a perspective view showing another example of the circulation of the strip.

FIG. 9 is a partial front view showing deformation of a tire during traveling.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 10, 10A, 10B belt-like body 11 belt cord 12 rubber B1, B2 folding point F1, F2 side edge L tire shaft

Claims (1)

[Claims] 1. A carcass consisting of a carcass ply in which a tread portion passes through a sidewall portion and is folded back around a bead core of a bead portion and carcass cords of a radial arrangement are juxtaposed, and inside the tread portion and outside in a radial direction of the carcass. A radial tire for an aircraft comprising a belt layer arranged, wherein the belt layer has one or a plurality of belt cords aligned in parallel and a rubberized belt is inclined with respect to a tire equator, and The belt-shaped member is formed by alternately turning back and forth in a V shape at turning points contacting at both side edges of the belt layer, and the belt-shaped body has an inclination angle θ intersecting with the tire equator at 5 ° or more and 25 on the tire equator. Radial tires for aircraft characterized by having a temperature of ° or less.