JP2007331707A - Bias tire for aircraft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To substantially improve pressure resistance with slight increase in weight. <P>SOLUTION: In a bias tire for an air craft, an even number of carcass plies 4 including a plurality of arranged fiber cords are mounted between a pair of bead parts 3, 3, and half of the carcass plies 4 are arranged so that the fiber cords are inclined in one direction with respect to a tire circumferential direction and remaining half of the carcass plies 4 are arranged so that the fiber cords are inclined in the other direction with respect to the tire circumferential direction. Reinforcing plies 7 having the same cord orientation as that of the carcass ply 4 positioned on an innermost side and having width W1 of 0.35 to 1.0 times as wide as grounding width W are integrally laminated with respect to the even number of carcass plies in a tread part 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aircraft bias tire having an even number of carcass plies, and more particularly to an aircraft bias tire that can significantly improve high-pressure resistance with a slight increase in weight.

  An aircraft bias tire has a bias structure in which a plurality of carcass plies are mounted between a pair of bead portions, and these carcass plies are arranged so that fiber cords cross each other between adjacent carcass plies. Such a bias structure is usually composed of an even number of carcass plies (see, for example, Patent Document 1 and Patent Document 2).

Aircraft bias tires are required to support a very large load with a structure that is as small and light as possible as compared with general vehicle tires. This is because, while taking off and landing, a very large load is applied to the tire, while the total weight of the aircraft is severely limited. In order to support a larger load, it is necessary to increase the internal pressure, and it is effective to increase the number of carcass plies in order to withstand the use conditions of ultra-high internal pressure. However, if the number of carcass plies is increased, the tire weight increases accordingly. Therefore, the method of increasing the number of carcass plies cannot sufficiently satisfy the required characteristics of aircraft bias tires.
JP-A-6-1105 JP-A-6-143913

  An object of the present invention is to provide an aircraft bias tire capable of significantly improving high pressure resistance with a slight increase in weight.

  In order to achieve the above object, an aircraft bias tire according to the present invention is configured such that an even number of carcass plies including a plurality of aligned fiber cords are mounted between a pair of bead portions, and half of the carcass plies are fibers. In the aircraft bias tire, the cord is arranged so as to be inclined in one direction with respect to the tire circumferential direction, and the remaining half of the carcass ply is arranged so that the fiber cord is inclined in the other direction with respect to the tire circumferential direction. A reinforcing ply having the same cord orientation as the innermost carcass ply and having a width of 0.35 to 1.0 times the ground contact width is integrally laminated on the even number of carcass plies in the tread portion. It is characterized by that.

  The present inventor has repeatedly conducted a test for destroying a tire by applying an internal pressure in a rim assembled state on an aircraft bias tire in which an even number of carcass plies are arranged so that fiber cords alternately cross between adjacent carcass plies. As a result, it was found that odd-numbered carcass plies, counted from the innermost side, break before even-numbered carcass plies, and tires often tear along the fiber cords of even-numbered carcass plies. did. Looking at the cause, in the final process of manufacturing the tire, that is, the vulcanization process, heat deterioration occurred in the fiber cord of the innermost carcass ply due to high temperature applied to the tire from the inside. There was found.

  Therefore, in the present invention, the same cord orientation as the innermost carcass ply is used to compensate for the cord deterioration of the carcass ply located on the innermost side in the tread portion where the force is most applied when internal pressure is applied to the tire. Reinforcing plies having are added locally. As a result, the breaking pressure of the aircraft bias tire can be effectively increased with a slight increase in weight, and the high-pressure resistance can be greatly improved.

  In the present invention, it is preferable to dispose an even number of carcass plies so that fiber cords alternately cross between adjacent carcass plies. In the case of such a bias structure, an excellent internal pressure holding capability can be exhibited.

  It is preferable to stack a single auxiliary ply on the even number of carcass plies. Increasing the number of auxiliary plies contributes to the improvement of the high pressure resistance, but when a plurality of auxiliary plies are added, the reinforcing efficiency is lowered and the weight is increased. That is, only one auxiliary ply is sufficient to compensate for the cord deterioration of the innermost carcass ply.

  In the present invention, the contact width is a contact width measured in the tire axial direction when the tire is grounded on a flat surface under the conditions of rated internal pressure and rated load defined by the American Tire and Rim Association (TRA).

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an aircraft bias tire according to an embodiment of the present invention. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. Between the pair of left and right bead portions 3 and 3, an even number of carcass plies 4 made of organic fiber cords are mounted. The organic fiber cord constituting the carcass ply 4 is not particularly limited, but nylon cord, polyester cord, or the like can be used.

  The carcass ply 4 is locked to the three bead cores 5 while being bundled in a plurality of ply groups 41 to 45. More specifically, the intermediate ply groups 42 to 44 except for the innermost ply group 41 and the outermost ply group 45 are wound around the bead core 5 from the tire inner side to the outer side, respectively. 45 are folded into the lower area of the three bead cores 5. These carcass plies 4 are arranged so that fiber cords alternately cross between adjacent carcass plies. That is, half of the carcass ply 4 is arranged so that the fiber cord is inclined in one direction with respect to the tire circumferential direction, and the other half of the carcass ply 4 is so arranged that the fiber cord is inclined in the other direction with respect to the tire circumferential direction. Is arranged. A tire having such a bias structure can withstand the use conditions of high internal pressure.

  On the outer peripheral side of the carcass ply 4 in the tread portion 1, a tread reinforcing layer 6 made of an organic fiber cord is embedded at a position separated from the carcass ply 4. These tread reinforcing layers 6 have a cord angle with respect to the tire circumferential direction set smaller than that of the carcass ply 4 and function as a reinforcing material for the tread portion 1.

  In the aircraft bias tire, the tread portion 1 has the same cord orientation as the innermost carcass ply 4 (4a) and a width W1 that is 0.35 to 1.0 times the ground contact width W. One reinforcing ply 7 is laminated integrally with the carcass ply 4. In particular, the reinforcing ply 7 is laminated on the outer peripheral side of the carcass ply 4 (4b) located on the outermost side. The reinforcing ply 7 can be composed of an organic fiber cord similar to the carcass ply 4.

  FIG. 2 shows an extracted carcass ply and reinforcement ply of the aircraft bias tire. In FIG. 2, the cord angle θ1 of the carcass ply 4 is set in a range of 30 ° to 34 °. On the other hand, the cord angle θ2 of the reinforcing ply 7 with respect to the tire circumferential direction is set in a range of 30 ° to 34 °. The cord angle θ2 of the reinforcing ply 7 is preferably substantially the same as the cord angle θ1 of the innermost carcass ply 4a. The cord angles θ1 and θ2 are measured at the tire equator position CL.

  In the above-described aircraft bias tire, the reinforcement ply 7 having the same cord orientation as the innermost carcass ply 4a is added to the tread portion 1 which is a portion to which the most force is applied when internal pressure is applied to the tire. Even if the organic fiber cord constituting the innermost carcass ply 4 is thermally deteriorated in the vulcanization process, the reinforcement ply 7 can compensate for the strength reduction due to the thermal deterioration of the organic fiber cord. Thereby, the breaking pressure of the aircraft bias tire can be effectively increased by a slight increase in weight caused by the reinforcing ply 7, and the high-pressure resistance can be greatly improved.

  Here, the width W1 of the reinforcing ply 7 needs to be 0.35 to 1.0 times the ground contact width W. If the width W1 of the reinforcing ply 7 is less than 0.35 times the ground contact width W, the effect of increasing the breaking pressure cannot be obtained. Conversely, if the width W1 exceeds 1.0 times the ground contact width W, the weight increase becomes significant. Further, sufficient consideration is required for the end position of the reinforcing ply 7. That is, since stress concentrates on the end portion of the reinforcing ply 7, it is desirable to dispose the end portion of the reinforcing ply 7 at a position avoiding the position immediately below the groove 8 where the expansion and contraction of the tread portion 1 is increased. In this way, when the end portion of the reinforcing ply 7 is disposed at a position avoiding the position immediately below the groove, a decrease in durability can be avoided.

  Tire size H44.5 × 16.5-21 28PR, an even number of carcass plies including a plurality of aligned fiber cords are mounted between a pair of bead portions, and these carcass plies are connected between adjacent carcass plies. In the aircraft bias tires arranged so that the fiber cords crossed alternately, tires of conventional examples, examples 1 to 4 and comparative examples 1 and 2 having different carcass structures as shown in Table 1 were produced.

  The conventional example and the comparative example 2 are tires to which no reinforcing ply is added. On the other hand, in Examples 1 to 4 and Comparative Example 1, reinforcing plies having the same cord orientation as the innermost carcass ply are laminated on the outer peripheral side of the outermost carcass ply in the tread portion, and the widths of the reinforcing plies are various. It is different. In Table 1, the width of the reinforcing ply is shown as a ratio to the contact width.

  These test tires were evaluated for breaking pressure and mass by the following test methods, and the results are also shown in Table 1.

Breaking pressure:
The test tire was assembled into a rim, and the cavity was filled with water, the water pressure was gradually increased, and the breaking pressure when the tire broke was measured. The evaluation results are shown as an index with the conventional example being 100. A larger index value means a higher breaking pressure.

mass:
The mass of the test tire was measured. The evaluation results are shown as an index with the conventional example being 100. A smaller index value means a lighter weight.

  As can be seen from Table 1, the tires of Examples 1 to 4 were able to effectively increase the breaking pressure with a slight weight increase compared to the conventional example. On the other hand, since the tire of Comparative Example 1 had a narrow reinforcing ply, the effect of increasing the breaking pressure could not be obtained. In the tire of Comparative Example 2, the increase in mass was significant because the breaking pressure was increased by increasing the number of carcass plies.

1 is a half sectional view of an aircraft bias tire meridian according to an embodiment of the present invention. FIG. 2 is a development view showing an extracted carcass ply and a reinforcement ply of the aircraft bias tire of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass ply 5 Bead core 6 Tread reinforcement layer 7 Reinforcement ply 41-45 Ply group W Grounding width W1 Reinforcement ply width

Claims (3)

  An even number of carcass plies including a plurality of aligned fiber cords are mounted between a pair of bead portions, and half of the carcass plies are arranged so that the fiber cords are inclined in one direction with respect to the tire circumferential direction. In the aircraft bias tire in which the other half of the carcass ply is arranged so that the fiber cord is inclined in the other direction with respect to the tire circumferential direction, the carcass ply has the same cord orientation as the innermost carcass ply and is grounded. An aircraft bias tire in which a reinforcing ply having a width of 0.35 to 1.0 times the width is laminated integrally with the even number of carcass plies in a tread portion.   The aircraft bias tire according to claim 1, wherein the even number of carcass plies are arranged such that fiber cords alternately intersect between adjacent carcass plies. The aircraft bias tire according to claim 1 or 2, wherein a single auxiliary ply is laminated on the even number of carcass plies.

Images