AIRCRAFT PNEUMATIC TIRE

Abstract

An aircraft pneumatic tire includes a spirally wound belt layer in which a ribbon-shaped first strip material with a first belt cord including organic fibers and being covered with rubber is spirally wound; and zigzag belt layers in which a ribbon-shaped second strip material with a second belt cord including organic fibers and being covered with rubber extends and is wound in a circumferential direction while bending zigzag by being folded back at width directional end edges to an outer circumferential side of the spirally wound belt layers. The maximum width of the spirally wound belt layers is wider than the maximum width of the zigzag belt layers, and the width of the second strip material is wider than the width of the first strip material.

Claims

1. An aircraft pneumatic tire comprising: a pair of bead cores (6); a radial carcass (7) including one or more carcass plies (7a) extending toroidally between both the bead cores (6); and belt layers (10) that are disposed on an outer circumferential side of a crown region of the radial carcass (7) and reinforce the radial carcass (7),characterized in that the belt layers (10) include a spirally wound belt layer (20) that has one layer or a plurality of layers (21, 22, 23) stacked and in which a ribbon-shaped first strip material (26) with a first belt cord (26a) including organic fibers and being covered with rubber is spirally wound, and zigzag belt layers (30) in which a ribbon-shaped second strip material (36) with a second belt cord (36a) including organic fibers and being covered with rubber extends and is wound in a circumferential direction while bending zigzag by being folded back at width directional end edges (30a) to an outer circumferential side of the spirally wound belt layer (20) and in which a plurality of layers (31, 32, 33, 34) are stacked, a maximum width Ws of the spirally wound belt layer (20) is wider than a maximum width We of the zigzag belt layers (30), and a width Wse of the second strip material (36) is wider than a width Wss of the first strip material (26).

2. The aircraft pneumatic tire according to claim 1, wherein a ratio of the width Wse of the second strip material to the width Wss of the first strip material is in a range of 0.25≤Wss/Wse≤0.8.

3. The aircraft pneumatic tire according to claim 1, wherein the first belt cord (26a) of the spirally wound belt layer (20) extends at an angle of equal to or less than 5° relative to a tire equatorial plane (CL), and the second belt cord (36a) of the zigzag belt layers (30) extends at an inclination of an angle of 5° to 30° relative to the tire equatorial plane (CL), to folding-back points (36b) where the second belt cord (36a) is folded back at each width directional end edge (30a) of the zigzag belt layers (30).

4. The aircraft pneumatic tire according to claim 1, wherein a spacing (L1) between a cord center (26ac) of the first belt cord (26a) and the cord center (26ac) of the adjacent first belt cord (26a) is 1.1 to 2.0 times the diameter (d1) of the first belt cord (26a), and a spacing (L2) between a cord center (36ac) of the second belt cord (36a) and the cord center (36ac) of the adjacent second belt cord (36a) is 1.1 to 2.0 times the diameter (d2) of the second belt cord (36a).

5. The aircraft pneumatic tire according to claim 1, wherein the first strip material (26) has two to six first belt cords (26a) in a width direction, the second strip material (36) has seven to eleven second belt cords (36a) in the width direction, the number of the spirally wound belt layer (20) is in the range of one to five, and the number of the zigzag belt layers (30) is in the range of two to six.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 is a width direction sectional view of an aircraft pneumatic tire of a first embodiment of the present invention in a state in which the aircraft pneumatic tire is assembled in a prescribed rim and loaded with air to a prescribed internal pressure.

[0030] FIG. 2 is a width direction sectional view in which major parts on one lateral side of the aircraft pneumatic tire of FIG. 1 are enlarged.

[0031] FIG. 3 is a partial development view depicting a formation example of a spirally wound belt layer.

[0032] FIG. 4 is a partial development view depicting a formation example of a zigzag belt layer.

[0033] FIG. 5 is an enlarged vertical sectional view through the center of rotation of the main parts of the tire in the vicinity of the width directional end edge of the zigzag belt layer.

[0034] FIG. 6 is a width direction sectional view of a spiral winding strip material.

MODE FOR CARRYING OUT THE INVENTION

[0035] A first embodiment of an aircraft pneumatic tire 1 according to the present invention will be described based on FIGS. 1 to 6. FIG. 1 depicts a sectional view in a tire width direction of the aircraft pneumatic tire 1 (hereinafter referred to as the tire 1) of the first embodiment of the present invention. The tire 1 is assembled onto an applied rim 40.

[0036] In the figure, symbol CL corresponds to the tire width center, and indicates a tire equatorial plane which is a plane orthogonal to the tire rotational axis. The tire width direction is a direction parallel to the tire rotational axis, and the tire radial direction is a direction of approaching or spacing away from the tire rotational axis perpendicularly to the tire rotational axis.

[0037] The tire 1 includes bead sections 5 in which a pair of left and right ring-shaped bead cores 6 are embedded; a radial carcass 7 arranged to extend toroidally between the pair of bead cores 6; belt layers 10 in circumferential contact with the radial directional outer side of the radial carcass 7; a tread section having a tread rubber 38 in circumferential contact with an outer circumferential surface of the belt layers 10; and side wall sections 4 covering side portions of the tire 1.

[0038] The radial carcass 7 has one or more carcass plies 7a stacked, for example, four to seven carcass plies 7a are stacked, and both end portions thereof are fixed by being wound up to the radial directional inner side to the outer side in the periphery of the bead cores 6. In the tire 1 of the present embodiment, seven carcass plies 7a including nylon cords are stacked.

[0039] On the tire radial directionally outer side on the outer circumferential side of a crown region 7b of the radial carcass 7, the belt layers 10 reinforcing the radial carcass 7 are provided. The belt layers 10 include spirally wound belt layers 20 wound on the outer circumferential surface of the radial carcass 7, zigzag belt layers 30 stacked on the outer circumference of the spirally wound belt layers 20, and a protective belt layer 37 wound around the outer circumference of the zigzag belt layers. The tread rubber 38 is attached to the outer circumferential surface of the protective belt layer 37, to form the tread section 3. Both ends of the belt layers 10 in the width direction are defined as width directional end edges 10a.

[0040] As depicted in FIGS. 3 to 5, the spirally wound belt layers 20 and the zigzag belt layers 30 are respectively made of a spiral winding strip 26 as a ribbon-shaped first strip material and a zigzag winding strip 36 as a ribbon-shaped second strip material, which are wound in a predetermined manner of winding respectively. The spiral winding strips 26, the zigzag winding strips 36, the organic fiber-made first belt cords 26a, and the organic fiber-made second belt cords 36a are aligned in plural numbers, and the assembly is covered with rubber, to be formed in a ribbon shape with a predetermined width.

[0041] As the organic fiber-made belt cords 26a and 36a used for the spiral winding strip 26 and the zigzag winding strip 36, organic fiber cords of an aromatic polyamide such as aramid are used. Alternatively, hybrid fiber cords produced by combining an aromatic polyamide and an aliphatic polyamide such as nylon may also be used.

[0042] The hybrid cord of the aliphatic polyamide fiber and the aromatic polyamide fiber may be a twined combination of yarn of an aliphatic polyamide fiber and yarn of an aromatic polyamide fiber or may be twined yarn obtained by twining preliminarily hybridized yarn of an aliphatic polyamide fiber and an aromatic polyamide fiber.

[0043] The number of the belt cords 26a of the spiral winding strips 26 is preferably in the range of two to six, and, in the present embodiment, the number is set to four as depicted in FIG. 6. The width Wss of the spiral winding strips 26 is preferably in the range of 3.0 to 9.0 mm, and, in the present embodiment it is set to 6.0 mm.

[0044] A spacing L1 between a cord center 26ac of the belt cord 26a and the cord center 26ac of the adjacent belt cord 26a in the spiral winding strip 26 is preferably in the range of 1.1 to 2.0 times the diameter d1 of the belt cord 26a.

[0045] As the belt cords 26a of the spiral winding strips 26, for example, hybrid cords including aramid and nylon or aramid cords composed only of aramid is used.

[0046] The number of the belt cords 36a of the zigzag winding strips 36 is preferably in the range of seven to eleven, and, in the present embodiment, the number is set to nine as depicted in FIG. 5. The width Wse of the zigzag winding strips 36 is preferably in the range of 6.0 to 18.0 mm, and, in the present embodiment, it is set to 12.0 mm.

[0047] The spacing L2 between a cord center 36ac of the belt cord 36a and the cord center 36ac of the adjacent belt cord 36a in the zigzag winding strip 36 is preferably in the range of 1.1 to 2.0 times the diameter d2 of the belt cord 36a.

[0048] As the belt cords 36a, for example, hybrid cords including aramid and nylon or aramid cords composed only of aramid are used.

[0049] As illustrated in FIGS. 1, 2, and 3, the spirally wound belt layers 20 of the tire 1 have a structure in which the spiral winding strips 26 as described above are spirally wound on the crown region 7b of the radial carcass 7 of a raw tire. The spirally wound belt layers 20 have the spiral winding strip 26 helically wound in the tire circumferential direction with a predetermined amount of deviation in the tire width circumferential direction such that gaps are not generated between the spiral winding strip 26 and the adjacent spiral winding strips 26.

[0050] As depicted in FIGS. 2 and 3, the spiral winding strip 26 is folded back after being wound to the width directional end edge 20a of the spirally wound belt layer 20, a second layer 22 starts being wound on an outer circumferential surface of a first layer 21, is wound around toward the other width directional end edge 20a, and is sequentially folded back and stacked, and, thus, the first layer 21 and a third layer 23 of the spirally wound belt layers 20 are stacked.

[0051] The spiral winding strip 26 is wound with the angle of its belt cord 26a set to a predetermined angle relative to the tire equatorial plane CL. In the present embodiment, the spiral winding strip 26 is wound such that the belt cord 26a is at an angle of equal to or less than 5° relative to the tire equatorial plane CL. When the spiral winding strip 26 starts being wound on the crown region 7b of the radial carcass 7, the winding is started from a position of the width directional end edge 10a in the tire width direction of the belt layers 10.

[0052] The number of the spirally wound belt layers 20 is preferably in the range of one to five, and, in the present embodiment, the spirally wound belt layers 20 are composed of three layers of the first layer 21, the second layer 22, and the third layer 23 from the inside in the tire radial direction.

[0053] In the spirally wound belt layers 20, the spiral winding strip 26 is wound such as to have a predetermined angle relative to the tire equatorial plane CL and such as not to generate gaps between the spiral winding strip 26 and the adjacent spiral winding strips 26. Thus, in the vicinity of the width directional end edges 20a of the spirally wound belt layer 20, non-stacked regions 20b where the spiral winding strip 26 is not wound is generated, as depicted in FIG. 3. As the width Wss of the spiral winding strip 26 is larger, the area of the non-stacked regions 20b becomes larger, resulting in a lowering in the strength at end portions of the spirally wound belt layer 20 in the width direction. In view of this, the width Wss of the spiral winding strip 26 is narrowed, whereby the strength at width directional end edges 20a of the spirally wound belt layer 20 is enhanced.

[0054] The zigzag belt layers 30 are configured by winding the zigzag winding strip 36 by a predetermined method, as depicted in FIGS. 4 and 5, on an outer circumferential side of the spirally wound belt layers 20. As illustrated in FIG. 1, the zigzag winding strip 36 is wound on the spirally wound belt layers 20 such that the maximum width We of the zigzag belt layers 30 is narrower than the maximum width Ws of the spirally wound belt layers 20.

[0055] The zigzag belt layers 30 have a structure in which the zigzag winding strip 36 is folded back at width directional end edges 30a of the predetermined zigzag belt layers 30 and extends and is wound in the circumferential direction while bending zigzag. The zigzag winding strip 36 is wound with a desired amount of deviation in the circumferential direction so as not to generate gaps between the zigzag winding strip 36 and the adjacent zigzag winding strips 36.

[0056] The zigzag winding strip 36 is wound such that the belt cord 36a of the zigzag winding strip 36 extends at an inclination of an angle of 5° to 30° relative to the tire equatorial plane CL, to folding-back points 36b folded back at both width directional end edges 30a of the zigzag belt layers 30.

[0057] The zigzag belt layers 30 are a plurality of layers stacked in a prescribed number, the number being preferably in the range of two to six and being four in the present embodiment.

[0058] In the vicinity of the width directional end edges 30a of the zigzag belt layers 30, the zigzag winding strip 36 is folded and is stacked in plural numbers. Thus, if the width of the zigzag winding strip 36 is narrow, the area of that part of the folding-back parts where three or four layers are stacked is enlarged, possibly leading to a trouble at the width directional end edges 10a of the belt layers 10. In view of this, the width of the zigzag winding strip 36 is set large, whereby the strength of the zigzag belt layers 30 is enhanced.

[0059] As described above, as the width Wss of the spiral winding strip 26 is narrower, the strength of the spirally wound belt layers 20 can be enhanced, while as the width Wse of the zigzag winding strip 36 is wider, the strength of the zigzag belt layers 30 can be enhanced. In view of this, the width Wse of the zigzag winding strip 36 is set larger than the width Wss of the spiral winding strip 26, and the ratio between the width Wse of the zigzag winding strip 36 and the width Wss of the spiral winding strip 26 is preferably in the range of

0.25≤Wss/Wse≤0.8

whereby the strength of the belt layers 10 as a whole can be more enhanced.

[0060] After the raw tire is produced such as to obtain a state in which the spirally wound belt layers 20, the zigzag belt layers 30, and the protective belt layer 37 are wound on the circumferential direction outer side of the crown region 7b of the radial carcass 7 and the tread rubber 38 is wound on the outer circumferential surface thereof, the raw tire is subjected to vulcanization molding, whereby the tire 1 of the present embodiment is obtained.

[0061] Since the tire 1 of the present embodiment is configured as described above, by narrowing the width Wss of the spiral winding strip 26 to thereby reduce the area of the non-stacked regions 20b in the vicinity of the width directional end edges 20a of the spirally wound belt layers 20, the strength at the width directional end edges 20a of the spirally wound belt layers 20 can be enhanced. In addition, by widening the width Wse of the zigzag winding strip 36 to thereby reduce the area of the part where three or four or more zigzag winding strips 36 are stacked at the width directional end edges 30a of the zigzag belt layers 30, the strength in the vicinity of the width directional end edges 30a of the zigzag belt layers 30 can be enhanced. Thus, the strength of the tire 1 as a whole can be enhanced.

EXAMPLES

[0062] Each of the tires having the abovementioned configuration and a size of 52×22.OR22, of Prior Art Examples 1 and 2 and Examples 1 to 6 of which the specifications are set forth in Table 1 and those of Prior Art Examples 3 and 4 and Examples 7 to 12 of which the specifications are set forth in Table 2, belt cord strength after drum traveling is obtained, and the results are represented in terms of indices.

[0063] The tires set forth in Tables 1 and 2 all include the radial carcass 7 having seven carcass plies 7a including nylon cords being stacked; and the belt layers 10 including the spirally wound belt layers 20 and the zigzag belt layers 30. In the tires set forth in Table 1, aramid is used as the belt cord material for the spiral winding strip 26 and the zigzag winding strip 36. In the tires set forth in Table 2, hybrid cords including aramid and nylon are used as the belt cord material for the spiral winding strip 26 and the zigzag winding strip 36.

TABLE-US-00001 TABLE 1 Prior Prior Art Art Example Example Example Example Example Example Example Example 1 2 1 2 3 4 5 6 Strip material 6.0 12.0 6.0 6.0 6.0 6.0 4.5 3.0 width of spirally wound belt layer Strip material 6.0 12.0 12.0 10.5 9.0 7.5 12.0 12.0 width of zigzag belt layer Wss/Wse 1.00 1.00 0.50 0.57 0.67 0.80 0.38 0.25 Belt cord Aramid Aramid Aramid Aramid Aramid Aramid Aramid Aramid material Belt cord Spirally 97 80 97 97 97 97 99 100 strength wound after belt drum layer traveling Zigzag 80 98 98 96 94 91 98 98 belt layer

TABLE-US-00002 TABLE 2 Prior Prior Art Art Example Example Example Example Example Example Example Example 3 4 7 8 9 10 11 12 Strip material 6.0 12.0 6.0 6.0 6.0 6.0 4.5 3.0 width of spirally wound belt layer Strip material 6.0 12.0 12.0 10.5 9.0 7.5 12.0 12.0 width of zigzag belt layer Wss/Wse 1.00 1.00 0.50 0.57 0.67 0.80 0.38 0.25 Belt cord Hybrid Hybrid Hybrid Hybrid Hybrid Hybrid Hybrid Hybrid material Belt cord Spirally 98 86 98 98 98 98 99 100 strength wound after belt drum layer traveling Zigzag 86 99 99 97 96 94 99 99 belt layer

[0064] The belt cord strength after drum traveling is measured as follows. Each tire is attached to a prescribed rim, is filled with air to a prescribed pressure, and is subjected to a drum test. After drum traveling for a predetermined distance under a load and a speed in simulation of a market, the tire 1 is dissected, the belt cords 26a and 36a on the outermost side in the width direction of the spirally wound belt layers 20 and the zigzag belt layers 30 are taken out and are subjected to measurement of strength, and the strength is evaluated. The test results are represented in terms of index with the strength of the cord taken out from a new tire set as 100, and are compared. A higher index indicates small fatigue of the belt cord and good fatigue resistance performance, and indicates that the tire is higher in durability.

[0065] In Examples 1 to 12 of the present invention, since the tire is configured as described above, durability of the spirally wound belt layers 20 and durability of the zigzag belt layers 30 are both secured, and durability of the tire 1 can be enhanced.

[0066] While the embodiment of the present invention has been described above, it is natural that the modes of the present invention are not limited to the abovementioned embodiment, and include the modes carried out in various forms within the scope of the gist of the present invention.

REFERENCE SIGNS LIST

[0067] 1: Aircraft pneumatic tire

[0068] 3: Tread section

[0069] 4: Side wall section

[0070] 5: Bead section

[0071] 6: Bead core

[0072] 7: Radial carcass

[0073] 7a: Carcass ply

[0074] 7b: Crown region

[0075] 10: Belt layer

[0076] 10a: Width directional end edge

[0077] 20: Spirally wound belt layer

[0078] 21: First layer

[0079] 22: Second layer

[0080] 23: Third layer

[0081] 26: Spiral winding strip

[0082] 26a: Belt cord

[0083] 26ac: Cord center

[0084] 30: Zigzag belt layer

[0085] 31: First layer

[0086] 32: Second layer

[0087] 33: Third layer

[0088] 34: Fourth layer

[0089] 36: Zigzag winding strip

[0090] 36a: Belt cord

[0091] 36ac: Cord center

[0092] 36: Folding-back point

[0093] 37: Protective belt layer

[0094] 38: Tread rubber

[0095] 40: Applied rim

[0096] CL: Tire equatorial plane

[0097] Ws: Maximum width of spirally wound belt layer.

[0098] We: Maximum width of zigzag belt layer

[0099] Wss: Width of spiral winding belt strip

[0100] Wse: Width of zigzag belt strip

[0101] d1: Diameter

[0102] d2: Diameter

[0103] L1: Spacing

[0104] L2: Spacing.