Lightweight aircraft tire

Abstract

To provide an improved aircraft tire which can support the high speed and high load while being reduced in weight.SOLUTION: A pneumatic tire includes a carcass and a belt reinforcement structure. The belt reinforcement structure comprises a main belt structure which includes a first belt layer and a first zigzag belt reinforcement structure. The first belt layer has a cord which is arranged at an angle equal to or less than 5 degrees with respect to the intermediate circumferential surface. The first zigzag belt reinforcement structure forms two layers of cords. The cords are inclined at 5 to 30 degrees with respect to the center circumferential surface and alternately extend to the folded point of the end in each lateral direction. The first zigzag belt reinforcement structure is wider than the first belt layer. The belt reinforcement structure further includes an auxiliary belt which is located on the radial direction outer side of the main belt. The auxiliary belt is the zigzag belt. The belt reinforcement structure further includes a cut protector belt 70 that is located on the radial direction outer side of an auxiliary layer. The cut protector belt 70 is the zigzag belt or geodesic line belt.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a pneumatic tire having a carcass and a belt reinforcement structure, and more particularly to a high-speed and high-load tire such as used in aircraft.

Background Art

[0002] Pneumatic tires for high-speed applications are subject to high levels of flexing in the crown region of the tire as the tire enters and exits the contact patch area. This problem is particularly exacerbated in aircraft tires where the tire can reach speeds in excess of 200 miles per hour during takeoff and landing.

[0003] As the tire rotates at very high speeds, the dimensions of the crown region tend to increase due to high angular acceleration and speed, tending to pull the tread region radially outward. Counteracting these forces is the vehicle load, which is supported only in a small area of the tire known as the contact patch area.

[0004] Current tire design drivers are aircraft tires that can be lightweight while still being capable of high speed and high load. In the prior art, it is known to use a zigzag belt layer in aircraft tires, as disclosed in Watanabe of U.S. Patent No. 5,427,167. The zigzag belt layer has the advantage of eliminating cut belt ends at the outer lateral edges of the belt package. The inherent flexibility of the zigzag belt layer also helps to improve cornering forces. However, tires designed to have a zigzag belt layer cannot carry as heavy a load as is required by current commercial aircraft design requirements. Further, generally there is a trade-off between load capacity and weight. Thus, there is a need for an improved aircraft tire that can be lightweight while still being capable of high speed and high load.

Summary of the Invention

[0005] (Definition) "Carcass" means a tire structure other than the belt structure, tread, undertread, and sidewall rubber on the ply, and includes the bead.

[0006] "Circumferential" means a line or direction extending along the perimeter of the annular tread surface perpendicular to the axial direction.

[0007] "Cord" means one of the reinforcing strands that make up the ply of a tire.

[0008] "Equatorial plane (EP)" means a plane perpendicular to the axis of rotation of the tire and passing through the center of the tread of the tire.

[0009] "Ply" means a continuous layer of parallel cords coated with rubber.

[0010] "Radial" and "radially" mean a direction radially towards the axis of rotation of the tire or a direction radially away from the axis of rotation of the tire.

[0011] "Radial ply tire" means a belt structure or pneumatic tire constrained circumferentially, with the ply cords extending from bead to bead and arranged at a cord angle of 65 to 90 degrees with respect to the equatorial plane of the tire.

[0012] "Zigzag belt reinforcement structure" means at least two layers of cords or a ribbon of parallel cords, each ribbon having 1 to 20 cords, and arranged in an alternating pattern extending at an angle of 5 to 30 degrees between the lateral ends of the belt layer. The present invention will be described by way of example with reference to the following accompanying drawings.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0014] FIG. 1 shows a cross-sectional view of a half of a radial aircraft tire 10 of the present invention. The tire is symmetric about a central circumferential plane, and only one half is shown. As shown, the aircraft tire includes a pair of bead portions 12, each including a bead core 14 embedded therein. An example of a bead core suitable for use in an aircraft tire is shown in U.S. Patent No. 6,571,847. The bead core 14 preferably has aluminum, an aluminum alloy or other lightweight alloy in a central portion, and the central portion is surrounded by a plurality of steel sheath wires. Those skilled in the art will be able to understand that other bead cores are also available.

[0015] The aircraft tire further includes a sidewall portion 16, and the sidewall portion 16 extends substantially outward from each of the bead portions 12 in the radial direction of the tire. The aircraft tire further includes a tread portion 20, and the tread portion 20 extends between the radially opposite end portions of the sidewall portion 16. Further, the tire 10 is reinforced by a carcass 22, and the carcass 22 extends annularly from one bead portion 12 to the other bead portion 12. The carcass 22 is preferably composed of an inner carcass ply 24 and an outer carcass ply 26, and these are oriented in the radial direction. Among these carcass plies, typically four inner plies 24 are wound around the bead core 14 from the inner side to the outer side of the tire to form a folded-back portion, while typically two outer plies 26 extend downward to the bead core 14 along the outside of the folded-back portion of the inner carcass ply 24. Each of these carcass plies 24, 26 contains any suitable cord, and typically may contain a nylon cord such as a nylon-6,6 cord. Each of the carcass plies 24, 26 extends substantially perpendicular to the equatorial plane EP of the tire (i.e., extends in the radial direction of the tire). Preferably, the nylon cord has a 1890 denier / 2 / 2 or 1890 denier / 3 structure. One or more of the carcass plies 24, 26 may include an aramid and nylon cord structure, for example, may include a hybrid cord, a high energy cord, or a mixed cord. Examples of suitable cords are described in U.S. Patent No. 4,893,665, U.S. Patent No. 4,155,394, or U.S. Patent No. 6,799,618.

[0016] (Main belt layer) The aircraft tire 10 further includes a main belt package 40, and the main belt package 40 is disposed between the carcass 22 and the tread rubber 20. FIG. 2 shows a first embodiment of a half portion of the belt package 40 suitable for use in an aircraft tire. Since the main belt package 40 is symmetric with respect to the central circumferential surface, only half of the belt package is shown. The illustrated main belt package 40 includes a plurality of belt layers located adjacent to the carcass. The belt layers are arranged such that their widths decrease, with the outermost belt in the radial direction having the smallest width and the innermost belt in the radial direction having the largest width. The innermost belt 42 in the radial direction is preferably a low-angle belt layer, and its angle is less than 10 degrees. More preferably, the innermost belt in the radial direction is less than 5 degrees and is wound spirally. The width of the low-angle belt is preferably in the range of 40% to 100% of the widest belt width.

[0017] The main belt layer 40 further includes one or more zigzag belt layers 44. Preferably, at least two zigzag belt layers 44, 46 are provided. More preferably, three zigzag belt layers 44, 46, 48 are provided. The angle of the zigzag belt layer is in the range of 10 degrees to 40 degrees. The zigzag belt layer is formed by winding one or more strips of cord in a zigzag pattern on a drum. The main belt layer is preferably formed from a hybrid or mixed cord of nylon and aramid. More preferably, the main belt cord structure is 3000d / 2 aramid and 1680d / 1 nylon.

[0018] The belt package 40 further includes an auxiliary belt layer 50, and the auxiliary belt layer 50 is located radially outside the main belt layer 50. The auxiliary belt layer 50 is preferably a zigzag belt layer and is formed of a nylon cord having a structure of 1890d / 4 or 1890d / 3. The angle of the auxiliary belt layer can be in the range of 0 degrees to 30 degrees. The auxiliary belt layer has a smaller width than the main belt layer 40, and the belt width is preferably in the range of 50% to 1110% of the widest layer of the main belt width.

[0019] The cushion gum layer 60 is located radially outside the auxiliary belt layer 50. The cushion gum layer 60 is formed from a hard rubber compound and preferably has a modulus of elasticity of 20 to 22 mpa.

[0020] The cut protector belt 70 is located radially outside the cushion gum layer 60. The cut protector belt may be formed of nylon, but is preferably made of a hybrid or mixed cord of nylon and aramid. Preferably, the cut protector belt 70 is formed from a mixed cord of two aramid cords having a 3000d / 2 structure and a nylon cord having a 1680d / 1 cord structure. The two aramid cords and the nylon cord are twisted together to form a mixed cord. The cut protector belt may be a zigzag belt, and more preferably a geodesic belt. The geodesic belt is shown in FIG. 3 and is made by the process described in U.S. Patent No. 9,199,512, which is incorporated herein by reference in its entirety. The geodesic belt is selected to have a high density of cords in the crown region of the belt and a sparse amount of cords in the shoulder region.

[0021] Modifications of the present invention are possible in light of the description provided herein. For purposes of illustration of the present invention, specific representative embodiments and details have been shown, but it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the present invention. Accordingly, it is to be understood that changes may be made in the particular embodiments described, which are described as being within all intended scopes of the present invention as defined by the following appended claims.

Claims

1. A pneumatic tire having a carcass and a belt reinforcing structure, wherein the belt reinforcing structure has a main belt structure including a first belt layer and a first zigzag belt reinforcing structure, the first belt layer has cords arranged at an angle of 5 degrees or less with respect to the central circumferential surface, the first zigzag belt reinforcing structure forms two layers of cords, the cords are inclined at 5 to 30 degrees with respect to the central circumferential surface of the tire, and extend alternately to the turning points at the ends in each lateral direction, and the first zigzag belt reinforcing structure is wider than the first belt layer, the belt reinforcing structure further includes an auxiliary belt located radially outside the main belt structure, and the auxiliary belt is a zigzag belt, the belt reinforcing structure further includes a cut protector belt located radially outside the auxiliary belt, and the cut protector belt is a zigzag belt or a geodesic belt, a cushion layer is provided between the cut protector belt and the auxiliary belt, and the cushion layer is formed of a hard rubber having an elastic modulus of 19 to 22 mpa. A pneumatic tire characterized by this.

2. The pneumatic tire according to claim 1, wherein the zigzag belt reinforcing structure is located radially outside the first belt layer.

3. The pneumatic tire according to claim 1, wherein the first belt layer is formed by spirally winding the cords.

4. The pneumatic tire according to claim 1, wherein the cut protector belt is formed of nylon.

5. The pneumatic tire according to claim 1, wherein the cut protector belt is formed of a mixed cord of nylon and aramid.

6. The pneumatic tire according to claim 1, wherein the auxiliary belt is formed of a nylon cord.

7. The pneumatic tire according to claim 1, wherein the auxiliary belt is formed of a mixed cable of two nylon cords and one aramid cord.

8. The pneumatic tire according to claim 1, wherein the main belt structure is formed of a mixed cable of two aramid cords and one nylon cord.

9. The pneumatic tire according to claim 1, wherein the cut protector belt is formed of an aramid cord.

10. The pneumatic tire according to claim 1, wherein the cut protector belt is formed of aramid and nylon cords.

11. The pneumatic tire according to claim 1, wherein the cut protector belt is formed of one aramid and two nylon cords.

12. A pneumatic tire having a carcass and a belt reinforcing structure, wherein the belt reinforcing structure has a main belt structure having a first belt layer and a first zigzag belt reinforcing structure, the first belt layer has cords arranged at an angle of 5 degrees or less with respect to the central circumferential surface, the first zigzag belt reinforcing structure forms two layers of cords, the cords are inclined at 5 to 30 degrees with respect to the central circumferential surface of the tire, and extend alternately to the turning points at the ends in each lateral direction, and the first zigzag belt reinforcing structure is wider than the first belt layer, the belt reinforcing structure further includes a cut protector belt located radially outside the main belt structure, the cut protector belt is a zigzag belt or a geodesic belt, a cushion layer is provided between the cut protector belt and an auxiliary belt provided in the belt reinforcing structure, and the cushion layer is formed of a hard rubber having an elastic modulus of 19 to 22 mpa. The pneumatic tire is characterized by this.

13. The pneumatic tire according to claim 12, wherein the cut protector belt is formed of a cord mixed with nylon and aramid.

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