JP2012066798A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire reducible in weight and respectively suppressed in the generation of standing waves, the occurrence of the cut and peel-off caused by scratches and the generation of separation at both ends of an outer belt.SOLUTION: The tire includes: at least one layer of an inner belt 16 in which a cord is embedded in the whole region and the cord intersects the equator plane of the tire at a first angle that is an acute angle, and the cord extends in a tire circumference direction while meandering by bending on both edges 16A in the dire width direction; and at least one layer of an outer belt 18 which is arranged between the inner belt 16 and a tread 14 in a radial direction of the tire, and in which a cord is embedded in the whole region and the cord intersects the equator plane of the tire at a second angle that is an acute angle larger than the first angle, cut ends 18A on both sides in the tire width direction are folded inward in the tire width direction, and the cut ends 18A on both sides are positioned in a range of (0.15 to 0.35)W from the equator plane of the tire where W represents a grounded width of the tread 14.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire used in an aircraft.

  A structure is disclosed in which the belt layer extends in the tire circumferential direction while zigzag by being bent at both ends of the belt (see Patent Document 1 and Patent Document 2). Further, a structure is disclosed in which the inclination angle of the cord of the outer belt with respect to the tire circumferential direction is larger than the inclination angle of the cord of the inner belt and both ends of the outer belt are cut (see Patent Document 3).

  Further, a pneumatic tire is disclosed that includes a fold structure belt that is folded at at least one of the side edges in the width direction of the strip (see Patent Document 4 and Patent Document 5).

JP 2000-52710 A JP-A-6-211003 JP-A-5-193306 JP-A-2-141306 Japanese Patent Laid-Open No. 2-198828

  For example, pneumatic tires for aircraft are required to suppress the generation of standing waves during high-speed driving and to suppress the occurrence of cuts and peel-off due to trauma under the restrictions of weight reduction. These goals have been achieved.

  However, in the conventional examples according to Patent Documents 2 and 3 described above, the cord cut end portion of the outer belt is exposed, and it is considered that separation is likely to occur with the cord cut end portion as a nucleus.

  In view of the above facts, an object of the present invention is to reduce the weight and to suppress the occurrence of standing waves, the occurrence of cuts and peel-off due to trauma, and the occurrence of separation at both ends of the outer belt. And

  According to the first aspect of the present invention, there is provided at least one layer of a carcass disposed between the pair of bead portions in a toroidal shape, and a plurality of circumferential mains disposed on the outer side in the tire radial direction of the carcass and extending in the tire circumferential direction. A zigzag is formed between the tread formed with the groove and the carcass and the tread in the tire radial direction, intersecting the tire equator plane at an acute angle and bending at both ends in the tire width direction. However, at least one layer of an inner belt in which a cord extending in the tire circumferential direction is embedded in the entire region and the inner belt in the tire radial direction and the tread are disposed between the first belt and the tire equator plane. Cords that intersect at an acute second angle larger than the angle are embedded in the entire region, and the cut ends on both sides in the tire width direction are folded back inward in the tire width direction, When the contact width of the tread is W, the cut ends on both sides have at least one outer belt located in the range of (0.15 to 0.35) W from the tire equator plane. ing.

  Here, the lower limit of the position of the cut end portion of the outer belt is set to 0.15 W from the tire equatorial plane in order to avoid tire pressure resistance and concentration of strain at the time of ejection due to centrifugal force. The reason for setting the tire equatorial plane to 0.35 W is to avoid concentration of shear strain.

  In the pneumatic tire according to claim 1, the cord of the inner belt intersects at a first angle that is an acute angle with respect to the tire equatorial plane, and extends in the tire circumferential direction while zigzag by being bent at both ends in the tire width direction. Therefore, it is possible to reduce the number of layers while maintaining the total strength of the inner belt, thereby reducing the weight and suppressing the occurrence of standing waves. Moreover, since the cord of the outer belt intersects the tire equator plane at an acute second angle larger than the first angle, the occurrence of cut and peel-off due to trauma is suppressed. Furthermore, since the cut end portions on both sides of the outer belt in the tire width direction are folded back inward in the tire width direction, it is possible to avoid the cut end portions being positioned at the maximum width position of the outer belt where the shear strain is maximized. it can. Since the position of the cut end is appropriately set, the tire pressure resistance can be secured and the concentration of shear strain can be avoided. For this reason, generation | occurrence | production of the separation in the both ends of an outer side belt can be suppressed, respectively.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the cut end portion is disposed so as to avoid a position in the tire radial direction of the circumferential main groove.

  In the pneumatic tire according to claim 2, since the cut end portion of the outer belt is not located at the inner side in the tire radial direction of the circumferential main groove where deformation in the cross section becomes relatively large, the separation at the cut end portion Can be suppressed.

  According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the cut end portions are arranged so as to face each other in the tire width direction, and a complementary belt is provided between the cut end portions. It is arranged.

  When the folded cut end portions are arranged so as to face each other in the tire width direction, the number of belt plies between the cut end portions decreases, but in the pneumatic tire according to claim 3, the cut end portions Since the complementary belt is disposed between the belts, the number of belts on the outer belt can be made uniform.

  According to a fourth aspect of the present invention, in the pneumatic tire according to the third aspect of the present invention, the additional belt is disposed between the outer belt and the complementary belt.

  In the pneumatic tire according to claim 4, since the additional belt is disposed between the outer belt and the complementary belt, the progress of separation from the additional belt to the outside can be suppressed. it can.

  According to a fifth aspect of the present invention, in the pneumatic tire according to the third or fourth aspect, both ends of the complementary belt in the tire width direction are disposed so as to avoid the positions of the circumferential main grooves.

  In the pneumatic tire according to claim 5, both ends in the tire width direction of the complementary belt are not located at positions on the inner side in the tire radial direction of the circumferential main groove where deformation in the cross section is relatively large. Occurrence of separation at the part can be suppressed.

  As described above, according to the pneumatic tire of the first aspect of the present invention, weight reduction is achieved, standing waves are generated, cuts and peel-offs are caused by trauma, and separation is performed at both ends of the outer belt. It is possible to obtain an excellent effect that the occurrence of each can be suppressed.

  According to the pneumatic tire of the second aspect, it is possible to obtain an excellent effect that the occurrence of separation at the cut end portion of the outer belt can be suppressed.

  According to the pneumatic tire of the third aspect, it is possible to obtain an excellent effect that the number of belts in the outer belt can be made uniform.

  According to the pneumatic tire of the fourth aspect, it is possible to obtain an excellent effect that the progress of separation from the additional belt to the outside can be suppressed.

  According to the pneumatic tire of the fifth aspect, it is possible to obtain an excellent effect that it is possible to suppress the occurrence of separation at both ends of the complementary belt in the tire width direction.

It is sectional drawing which shows a pneumatic tire. It is a perspective view which shows an inner side belt. It is an expanded view which shows an inner side belt. (A) It is a principal part perspective sectional view which shows an outer side belt and a complementary belt. (B) It is a principal part expanded view which shows an outer side belt and a complementary belt. It is a principal part perspective sectional view which shows the example arrange | positioned so that an additional belt may be wrapped between an outer side belt and a complementary belt. (A) It is a principal part expanded sectional view which shows the positional relationship of the cutting end part of an outer side belt, the tire width direction both ends of a complementary belt, and the circumferential direction main groove. (B) It is a principal part expanded sectional view which shows the positional relationship of the tire width direction both ends of an outer side belt, and the circumferential direction main groove.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In FIG. 1, a pneumatic tire 10 according to the present embodiment is an aircraft tire, for example, and includes at least one carcass 12, a tread 14, at least one inner belt 16, and at least one outer belt. 18.

  The carcass 12 is disposed between the pair of bead portions 20 in a toroidal shape, and both ends of the carcass 12 are folded, for example, from the inner side in the tire width direction to the outer side with respect to the bead core 22 of the bead portion 20. A bead filler 24 is provided between the carcass 12 and the bead core 22.

  The tread 14 is disposed outside the carcass 12 in the tire radial direction. A plurality of circumferential main grooves 26 extending in the tire circumferential direction are formed in the tread 14.

  In FIG. 1, the inner belt 16 is disposed between the carcass 12 and the tread 14 in the tire radial direction. As shown in FIGS. 2 and 3, the cord 28 is embedded in the entire area of the inner belt 16. The cord 28 intersects the tire equatorial plane CL at an acute angle A, and is bent at both ends 16A in the tire width direction so as to extend in the tire circumferential direction while zigzag.

  Specifically, the inner belt 16 is provided with an elongated body 30 configured by rubber-covering one or more, usually one or several cords 32, and the elongated belt 30 is rotated approximately once in the tire circumferential direction. Each time it is wound, it is wound in the circumferential direction while reciprocating between both ends 16A in the tire width direction, for example, only once, and such winding is substantially the width of the elongated body 30 in the circumferential direction so that no gap is formed between the elongated bodies 30. It is formed by shifting many times.

  As a result, the cords 32 extending in the tire circumferential direction while being zigzag by changing the bending direction at both ends 16A in the tire width direction are embedded substantially uniformly in the entire region in each inner belt 16.

  If the inner belt 16 is formed by the above-described method, the cords 32 are doubled, so that the two inner belts 16 are formed so that the cords 32 cross each other between the layers at a time. .

  There are various sizes of pneumatic tires for aircraft. As described above, every time the elongate body 30 is made to make one round, the tire width direction both ends 16A are reciprocated only once. Even so, the cord 32 intersects the tire equatorial plane CL within a range of the first angle A of 5 to 15 °. As the cord 32, for example, a synthetic resin fiber such as nylon or Kevlar (polyamide fiber) or steel is used.

  In FIG. 1, the outer belt 18 is disposed between the inner belt 16 and the tread 14 in the tire radial direction. As shown in FIGS. 4A and 4B, the outer belt 18 has a cord 34 that intersects the tire equatorial plane CL at an acute second angle B larger than the first angle A in the entire region. The embedded end portions 18A on both sides in the tire width direction are folded back, for example, on the outer side in the tire radial direction and on the inner side in the tire width direction. That is, the outer belt 18 is a so-called fold belt.

  As shown in FIG. 6 (A), the cut end 18A is disposed so as to avoid the position in the tire radial direction of the circumferential main groove 26. As shown in FIG. 6B, in this embodiment, both ends 18B in the tire width direction of the outer belt 18 are also arranged so as to avoid the positions in the tire radial direction of the circumferential main grooves 26.

  In FIG. 1, when the ground contact width of the tread 14 is W, the cut ends 18A on both sides are located in a range of (0.15 to 0.35) W from the tire equatorial plane CL. When this range is converted to the full width centered on the tire equatorial plane CL, it is (0.3 to 0.7) W. Here, the reason why the lower limit of the position of the cut end portion 18A of the outer belt 18 is set to 0.15 W from the tire equatorial plane CL is to avoid tire pressure resistance and concentration of strain at the time of ejection due to centrifugal force. The reason why the upper limit is set to 0.35 W from the tire equatorial plane CL is to avoid concentration of shear strain.

  The “contact width” means that the pneumatic tire 10 is mounted on a standard rim prescribed in JATMA YEAR BOOK (2010 edition, Japan Automobile Tire Association Standard), and applied size and ply rating in JATMA YEAR BOOK. The outermost end in the tire width direction in the ground contact area when the maximum load capacity is loaded by filling the internal pressure of 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (inner pressure-bold load in the load capacity correspondence table) Is the distance between. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  As shown in FIG. 4, the cut end portions 18A on both sides are folded back outward in the tire radial direction and arranged to face the tire width direction, and a complementary belt 36 is interposed between the cut end portions 18A. It is arranged. In the present embodiment, the cord 38 of the complementary belt 36 is also embedded in the entire region in the same manner as the cord 34 of the outer belt 18 and intersects the tire equatorial plane CL at the second angle B. Both the end portions 36A in the tire width direction of the complementary belt 36 are desirably arranged so as to avoid the positions of the circumferential main grooves 26, like the cut end portions 18A of the outer belt 18. The interval between the cut end portion 18A and the tire width direction both end portions 36A is not limited to the illustrated example. This interval may be made smaller so that they are close to each other, or may be set so that they are in contact with each other.

  When the number of layers of the outer belt 18 is desired to be three or more, as shown in FIG. 5, an additional belt 40 may be disposed between the outer belt 18 and the complementary belt.

  In the tire width direction, the width of the inner belt 16 (distance between both ends 16A in the tire width direction) is, for example, (0.9 to 1.15) W. Thereby, the rigidity of both ends 16A in the tire width direction of the inner belt 16 can be improved, and the occurrence of standing waves can be suppressed.

  In the tire width direction, the width of the outer belt 18 (distance between both ends 18B in the tire width direction) is, for example, (0.6 to 0.85) W. The lower limit is set to 0.6 W, and if it is less than this, the cut at the time of trauma becomes easy to reach the inner belt 16 directly, and the upper limit is set to 0.85 W if it exceeds this, This is because the strain between the inner belt 16 and the outer belt 18 increases.

  In FIG. 6B, the interlayer distance D between the outer belt 18 and the inner belt 16 at the cut end 18A of the outer belt 18 is D ≧ d, where d is the diameter of the cord 34 of the outer belt 18. is there. This is because when D <d, the strain between the inner belt 16 and the outer belt 18 increases. In FIG. 6B, only a part of the cord 32 is drawn to show the interlayer distance D, but the cord 32 is embedded substantially uniformly in the entire area of the inner belt 16 as described above. Is.

(Function)
This embodiment is configured as described above, and the operation thereof will be described below. 1 to 6, in the pneumatic tire 10 according to the present embodiment, the cord 32 of the inner belt 16 intersects the tire equator plane CL at a first angle A that is an acute angle, and at both ends 16A in the tire width direction. Since it bends and extends in the tire circumferential direction while zigzag, it is possible to reduce the number of layers while maintaining the total strength of the inner belt 16, thereby reducing the weight and suppressing the occurrence of standing waves. Further, since the cord 34 of the outer belt 18 intersects the tire equator plane CL at an acute second angle B that is larger than the first angle, the occurrence of cut or peel-off due to trauma is suppressed.

  Furthermore, since the cut end portions 18A on both sides of the outer belt 18 in the tire width direction are folded back inward in the tire width direction, the maximum width position (the tire width direction both ends 18B) of the outer belt 18 at which the shear strain becomes maximum, It is possible to avoid the position of the cut end 18A. Furthermore, since the position of the cut end 18A is set appropriately, the tire pressure resistance can be secured and the concentration of shear strain can be avoided. For this reason, generation | occurrence | production of the separation in the tire width direction both ends 18B of the outer side belt 18 can be suppressed, respectively.

  In the outer belt 18, when the folded cut end portion 18A is arranged so as to face the tire width direction, the number of belt plies between the cut end portions 18A is reduced. Since the complementary belt 36 is disposed between the portions 18A, the number of belts in the outer belt 18 can be made uniform.

  Further, the cut end 18A of the outer belt 18, the tire width direction both ends 36A of the complementary belt 36, and the tire width direction both ends 18B of the outer belt 18 are formed in the circumferential main groove 26 where the deformation in the cross section is relatively large. Since there is no inner position in the tire radial direction, it is possible to suppress the occurrence of separation at the cut end 18A, both ends 36A in the tire width direction, and both ends 18B in the tire width direction.

  When the additional belt 40 is disposed between the outer belt 18 and the complementary belt 36 so as to wrap, the number of layers of the outer belt 18 is increased, and the progress of separation from the additional belt 40 to the outside is suppressed. be able to.

(Other embodiments)
In the above embodiment, the cut end 18A of the outer belt 18, the tire width direction both ends 36A of the complementary belt 36, and the tire width direction both ends 18B of the outer belt 18 are respectively in the tire radial direction inner position of the circumferential main groove 26. However, at least one of these portions may be disposed at the inner side in the tire radial direction of the circumferential main groove 26.

  The cut end 18A of the outer belt 18 is folded outward in the tire radial direction and arranged to face the tire width direction. However, the cut end 18A may be folded back in the tire radial direction. . Further, one of the cut end portions 18A on both sides may be folded back inward in the tire radial direction and the other folded back in the tire radial direction outside. In this case, the complementary belt 36 is omitted or disposed on the inner side and the outer side in the tire radial direction of the outer belt 18 in order to equalize the number of belts.

  The position of the cut end 18A of the outer belt 18 is not necessarily in the range of (0.15 to 0.35) W from the tire equatorial plane CL.

(Test example)
The tires according to the conventional examples, comparative examples, and examples 1 and 2 shown in Table 1 were tested for tire breaking pressure and the number of running times (durability) until the occurrence of an abnormality. The basic structure of the tire is as shown in FIG.

[Test conditions]
Tire size: 42 × 17.0R18
Internal pressure: Normal internal pressure Load: 100% of normal load
Speed: 64km / h
Running time: 10 minutes Test interval: 120 minutes Evaluation method: Sialography inspection (performed every 50 times after running 600 times)

  It supplements about the item of Table 1. The “position of the cut end portion of the outer belt” is a ratio to the contact width from the tire equatorial plane. The “outer width” and “inner belt width” are ratios (belt width / ground width) to the ground width. The “interlayer distance between both ends of the outer belt in the tire width direction” is a ratio to the cord diameter (interlayer distance between the outer belt and the inner belt / the cord diameter). The tire breaking pressure is indicated by an index with the conventional example being 100, and the larger the value, the better the result.

  According to this test result, in the comparative example, since the position of the cut end portion of the outer belt is not appropriate, the durability is lowered, but in Examples 1 and 2, each item is appropriately set. It was confirmed that the durability could be greatly improved.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Carcass 14 Tread 16 Inner belt 16A Both ends of tire width direction 18 Outer belt 18A Cutting end 20 Bead part 26 Circumferential main groove 28 Code 32 Code 34 Code 36 Complementary belt 36A Tire width direction both ends 40 Additional belt A 1st angle B 2nd angle CL Tire equatorial plane

Claims (5)

At least one layer of carcass disposed between the pair of bead portions in a toroidal shape;
A tread having a plurality of circumferential main grooves formed on the outer side in the tire radial direction of the carcass and extending in the tire circumferential direction;
A cord that is disposed between the carcass and the tread in the tire radial direction, intersects at a first angle that is an acute angle with respect to the tire equatorial plane, and extends in the tire circumferential direction while zigzag by being bent at both ends in the tire width direction. At least one layer of inner belt embedded in the entire area;
A cord that is disposed between the inner belt and the tread in the tire radial direction and intersects the tire equator plane at an acute second angle larger than the first angle is embedded in the entire region, and the tire width direction If the cut ends on both sides are folded back inward in the tire width direction and the ground contact width of the tread is W, the cut ends on both sides are located in the range of (0.15 to 0.35) W from the tire equatorial plane. At least one outer belt,
Pneumatic tire having   The pneumatic tire according to claim 1, wherein the cut end portion is disposed so as to avoid a position in the tire radial direction of the circumferential main groove. The cut end is arranged to face the tire width direction,
The pneumatic tire according to claim 1 or 2, wherein a complementary belt is disposed between the cut ends.   The pneumatic tire according to claim 3, wherein an additional belt is disposed between the outer belt and the complementary belt.   The pneumatic tire according to claim 3 or 4, wherein both ends of the complementary belt in the tire width direction are disposed so as to avoid the position of the circumferential main groove.

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