Patent ID: 11926182
Assignee: BRIDGESTONE CORPORATION
Field: Transport (Mechanical engineering)
Classification: CPC B  Y | IPC B

Claim 0:
1. An aircraft pneumatic tire comprising:
a pair of bead cores (6);
a radial carcass (7) including at least one carcass ply (7a) extending toroidally between both the bead cores (6); and
a belt layer (10) that is disposed on an outer circumferential side of a crown region of the radial carcass (7) and reinforces the radial carcass (7), characterized in that
the belt layer (10) includes
a spirally wound belt layer (20) in which a ribbon-shaped first strip material (26) with a first belt cord (26a) including organic fibers and being covered with rubber has a spirally wound structure, and a prescribed plurality of layers (21, 22, 23, 24, 25) are laid on one another, and
a zigzag belt layer (30) in which a ribbon-shaped second strip material (36) with a second belt cord (36a) including organic fibers and being covered with rubber has a structure of being wound and extending 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),

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),
the second belt cord (36a) of the zigzag belt layer (30) extends at an inclination of an angle of 2° to 45° 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 layer (30), and
a relation of

N95>N50, is satisfied,
where N50 is the number of stacked belt layers of the spirally wound belt layer (20) at a distance of 50% of half the length of a maximum belt width (Wb) of the belt layers (10) from the tire equatorial plane (CL), and
N95 is the number of stacked belt layers of the spirally wound belt layer (20) at a distance of 95% of half the length of the maximum belt width (Wb) from the tire equatorial plane (CL),
an innermost side layer (21) located on a most inner side in a tire radial direction, of the plurality of spirally wound belt layers (20), is disposed on one side of the tire equatorial plane (CL) in a tire width direction,
an inner end portion (21a) on an inner side in the tire width direction, of end portions (21a, 21b) of the innermost side layer (21) in the tire width direction, is located with a predetermined spacing Ws1 from the tire equatorial plane (CL),
an outer end portion (21b) on an outer side in the tire width direction, of the end portions (21a, 21b) of the innermost side layer (21), is located on a tire width directionally outer side than the inner end portion (21a) of the innermost side layer (21),
an outermost side layer (25) located on the most outer side in the tire radial direction, of the plurality of spirally wound belt layers (20), is disposed on said one side relative to the tire equatorial plane (CL) in the tire width direction,
an inner end portion (25a) on an inner side in the tire width direction, of end portions (25a, 25b) of the outermost side layer (25) in the tire width direction, is located with a predetermined spacing Ws2 from the tire equatorial plane (CL),
an outer end portion (25b) on an outer side in the tire width direction, of the end portions (25a, 25b) of the outermost side layer (25), is located on a tire width directionally outer side than the inner end portion (25a) of the outermost side layer (25), and
the plurality of spirally wound belt layers (20) comprises a folded back portion on the outer side in the tire width direction relative to the tire equatorial plane (CL), wherein the plurality of spirally wound belt layers (20) is folded back at a width directional end edge (20a), is folded back without being wound to the tire equatorial plane (CL), and is then folded back again at the width directional end edge (20a).