JP2005231583A - Pneumatic radial tire for high-speed and heavy load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve high-speed durability performance while effectively suppressing the generation of partial wear of a shoulder portion, in a radial tire 11 for high-speed and a heavy load. <P>SOLUTION: In the radial tire 11 for high-speed and the heavy load, a curvature CR of radius at a crown center portion 50 in a area A1 which is 35 to 40% of a grounding surface width Tw at specified inner pressure and a specified load with reference to the tire equator surface E is made to be 600 to 720mm at the specified inner pressure and no load. On both sides of the crown center portion 50, a curvature radius ShR of a shoulder portion 49 that is an area A2 from 85% to 110% of the grounding surface width Tw at specified inner pressure and the specified load with reference to the tire equator surface E is structured to be 30 to 50mm at specified inner pressure and no load. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-speed heavy-load pneumatic radial tire mounted on an aircraft or the like.

  In general, a pneumatic radial tire for high-speed heavy loads mounted on an aircraft or the like is in a use state in which the aircraft travels at a high speed while being loaded with a heavy load when the aircraft takes off, and high-speed durability performance is required.

In such a high-speed heavy-duty pneumatic radial tire, as an effective technique for improving high-speed durability performance, a technique is known in which an endless belt layer composed of a plurality of endless plies is disposed between a carcass layer and a tread rubber. (For example, see Patent Documents 1 to 3). Such an endless ply is formed by crossing the tire equator plane at a small angle and bending the cord alternately in opposite directions at both ends of the ply so that the cord extending in the tire circumferential direction is embedded almost uniformly in the entire region. Has been.
JP-A-8-207510 JP 2001-138712 A JP 7-179102 A

  However, according to the technique disclosed in Patent Document 1, although the durability of the tire is improved by arranging the endless belt layer, the rigidity at the end of the endless belt layer is near the tire equatorial plane of the endless belt layer. Therefore, there is a problem in that a diameter difference occurs between the crown center portion and the shoulder portion, and drag uneven wear occurs in the shoulder portion.

  Further, according to the technique disclosed in Patent Document 2, by increasing the radius of curvature of the endless belt layer in the vicinity of the tire equator plane, by reducing the diameter difference between the crown center portion and the shoulder portion, Drag uneven wear at the portion can be reduced.

  However, in the technique disclosed in Patent Document 2, the belt tension at the end portion of the endless belt layer is reduced by limiting the shape of the outer ring portion of the endless belt layer. As a result, the technique disclosed in Patent Document 2 has a problem in that it cannot satisfy the durability performance (ply rating of 40 PR or more) of a tire that will be required with the future enlargement of aircraft. It was.

  Further, according to the technique disclosed in Patent Document 3, by specifying the rubber thickness of the tire surface at the end of the endless belt layer, cracks in the shoulder can be suppressed, but uneven wear in the shoulder is prevented. There was a problem that it could not be suppressed.

  Therefore, the present invention has been made in view of the above-described problems, and in a high-speed heavy-duty pneumatic radial tire mounted on an aircraft or the like, while effectively suppressing the occurrence of uneven wear at the shoulder portion, the high-speed The purpose is to improve durability.

  In order to solve the above problems, the present invention is characterized by a toroidal carcass layer in which a large number of cords substantially perpendicular to the tire equatorial plane are embedded, and a tread disposed radially outward of the carcass layer. Rubber, and an endless belt layer composed of a plurality of endless plies disposed between the carcass layer and the tread rubber and stacked in the radial direction, and the endless ply at a small angle with respect to the tire equator plane. In a radial tire for high-speed heavy loads in which the cords extending in the circumferential direction of the tire are zigzag by crossing and alternately bending in opposite directions at both ends of the ply, the tire equatorial plane is from the tire equator to At the center of the crown in the region of 35 to 40% of the ground contact creepage width at the specified internal pressure and specified load The radius of curvature is 600 to 720 mm at the specified internal pressure and no load, on both sides of the crown center portion, and from 85% to 110% of the ground contact creepage width at the specified internal pressure and specified load with respect to the tire equatorial plane The gist is that the radius of curvature of the shoulder portion, which is the region of, is 30 to 50 mm when the specified internal pressure and no load are applied.

  According to this invention, by setting the radius of curvature at the crown center portion to 600 mm or more at the specified internal pressure and no load, a difference in diameter occurs between the crown center portion and the yash shoulder portion at the specified load. It is possible to prevent uneven wear due to dragging of the shoulder portion having a diameter smaller than the diameter of the crown center portion.

  Further, according to this invention, by setting the radius of curvature at the crown center portion to 720 mm or less at the specified internal pressure and no load, the contact pressure at the crown center portion is higher than the contact pressure at the shoulder portion at the specified load. By lowering, it is possible to avoid the occurrence of a diameter difference between the crown center portion and the shoulder, and to prevent occurrence of uneven wear in the crown center portion.

  Moreover, according to this invention, it can suppress that the gauge (thickness) of a shoulder part increases by making the curvature radius in a shoulder part into 30 mm or more at the time of a prescription | regulation internal pressure and no load, and heat accumulation amount is sufficient. The increase can be reduced.

  Further, according to the invention, by setting the radius of curvature at the shoulder portion to 50 mm or less at the specified internal pressure and no load, it is possible to prevent a diameter difference from occurring between the crown center portion and the shoulder portion, The occurrence of uneven wear due to dragging can be more reliably suppressed.

  In the above feature of the present invention, the creepage width of the endless ply of the outermost layer is 1.01 times or more of the grounding creepage width at a specified load and a specified internal pressure, and the creepage width of the endless ply of the outermost layer is the tire. You may be comprised so that it may be 1.05 times or more of the distance from the equator surface to the intersection of the normal line in the contact surface end on the tire surface at the specified load and specified internal pressure and the endless ply of the outermost layer. In such a case, the distortion generated at the end of the endless belt layer can be reduced.

  Further, in the above-described feature of the present invention, the endless belt layer is in a region from 70 to 75% of the ground contact creepage width at the specified internal pressure and specified load with respect to the tire equator plane as a reference from the tire equator plane. You may be comprised so that it may be substantially parallel with respect to the surface of the said tread rubber.

  According to the present invention, in a high-speed heavy-duty pneumatic radial tire mounted on an aircraft or the like, while effectively suppressing the occurrence of uneven wear in the shoulder portion, the high-speed durability performance is improved and the size of the future aircraft is increased. Accordingly, it is possible to cope with the durability performance (high ply rating) of the tire that would be required.

(Configuration of High-Speed Heavy Load Pneumatic Radial Tire According to One Embodiment of the Present Invention)
A high-speed heavy-duty pneumatic radial tire according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a high-speed heavy-load pneumatic radial tire according to this embodiment.

  As shown in FIG. 1, the radial tire 11 according to the present embodiment is a high-speed heavy-load pneumatic radial tire mounted on an aircraft or the like, and is disposed between the carcass layer 21 and the tread rubber 15 in the radial direction. A belt layer 29 composed of a plurality of laminated endless plies 31 and separating plies 32 is provided.

  The radial tire 11 includes a pair of bead portions 13 each having a bead core 12 embedded therein, and sidewall portions 14 formed from the bead portion 13 toward the outer side in the radial direction.

  Further, the radial tire 11 is reinforced by a toroidal carcass layer 21 extending from one bead portion 13 to the other bead portion 13. The carcass layer 21 is composed of one or more (eight layers in the present embodiment) carcass plies 22 that overlap each other.

  In the present embodiment, in each carcass ply 22, a cord made of a large number of nylon fibers or aramid fibers that are substantially orthogonal to the tire equatorial plane E (extending in the radial direction) is embedded.

  Among the carcass plies 22, six layers on the inner layer side are turn-up plies (four high turn-up plies 16 a and two low turn-up plies 16 b) folded around the bead core 12. The two layers on the side are down plies 16a extending to the bead core 12 along the outside of the folded portion.

  The tread rubber 15 is disposed on the outer side in the radial direction of the carcass layer 21, and a plurality of wide circumferential grooves 27 are formed in the tread rubber 15.

  In the present embodiment, a protective layer 35 that covers the belt layer 29 from the outside in the radial direction and protects the belt layer 29 from being cut is disposed between the belt layer 29 and the tread rubber 15.

  Here, with reference to FIG. 2, the structure of the endless ply 31 in the belt layer 29 in the present embodiment will be described in detail.

  As shown in FIG. 2, the endless ply 31 is moved back and forth between the ply ends 34 a and 34 b almost every round while being shifted by the width of the ribbon 33 so that no gap is generated between the ribbons 33. However, it is formed by winding a plurality of ribbon-like bodies 33 in the circumferential direction. The ribbon-like body 33 is constituted by arranging a plurality of cords 36 made of nylon fibers, aramid fibers, or the like and covering them with rubber.

  That is, each endless ply 31 intersects the tire equator plane E at a small angle (for example, an angle of 5 to 20 degrees), and the ply ends 34a and 34b are alternately bent in opposite directions to zigzag the tire. A cord 36 extending in the circumferential direction is embedded substantially uniformly in the entire region.

  At the ply ends 34a and 34b, the ribbon-like body 33 may be bent in an arc shape or may be bent via a short straight portion extending in the circumferential direction along the ply ends 34a and 34b. .

  Since the endless ply 31 is formed by folding and winding the ribbon-like body 33, the cord 36 has a double-layer structure in which the cords 36 are doubled, and the cords 36 cross each other between the two layers. Yes.

  Further, the endless ply 31 having such a two-layer structure is a “knitted ply structure” in which both ends in the width direction are closed (edges are continuous), and the cord 36 does not have a separated end. ing. According to the structure of the endless ply 31, interlayer shear strain at the ply ends 34 a and 34 b can be significantly reduced, and separation at the ply ends 34 a and 34 b can be suppressed.

  Further, according to the structure of the endless ply 31, since the crossing angle of the cord 36 with respect to the tire equator line E can be reduced by reducing the interlaminar shear strain, the weight of the tire can be reduced.

  Furthermore, according to the structure of the endless ply 31, the extension direction of the cord 36 at the ply ends 34 a and 34 b is an angle close to the circumferential direction. (Standing wave resistance) can be improved.

  On the other hand, in each separation ply 32, a large number of cords 36 inclined at the same predetermined angle (for example, an angle of 10 to 35 degrees) with respect to the tire equatorial plane E are embedded almost uniformly in the entire region. The cord 36 is terminated at the ply ends 34a and 34b, that is, the cut end is exposed. Further, at least two of the separating plies 32 are arranged so that the cords 36 cross each other between the two layers, that is, are inclined in the opposite direction.

  As shown in FIG. 2, in the radial tire 11 according to the present embodiment, a region from the tire equatorial plane E to 35 to 40% of the ground contact creepage width Tw at the time of a specified internal pressure and a specified load with reference to the tire equatorial plane E. The radius of curvature CR at the A1 crown center portion 50 is 600 to 720 mm at the specified internal pressure and no load.

  Further, in the radial tire 11 according to the present embodiment, in the region A2 that is located on both sides of the crown center portion 50 and is 85% to 110% of the ground contact creepage width Tw at the specified internal pressure and the specified load with respect to the tire equatorial plane E. The curvature radius ShR at a certain shoulder portion 49 is 30 to 50 mm when the specified internal pressure and no load are applied.

  Further, the creepage width W of the outermost endless ply 31a is 1.01 or more times the ground creepage width Tw at the specified load and the specified internal pressure. Further, the creepage width W of the outermost endless ply 31a is determined from the tire equator plane E to the normal line (AB) at the ground contact end A on the tire surface at the specified load and specified internal pressure, and the outermost endless ply 31a. It is 1.05 times or more the distance Wb to the intersection B.

  Further, the endless ply 31 is located on the surface of the tread rubber 15 in the region Wp from the tire equatorial plane E to 70 to 75% of the contact creepage width Tw at the specified internal pressure and the specified load with reference to the tire equatorial plane E. Are almost parallel.

  Next, test examples will be described. As tests, a durability test using a drum tester and a wear test using a drum tester were performed.

(Durability test with drum tester)
In this test, using conventional tires having the values shown in Table 1 below, tires according to comparative examples, and tires according to examples, each tire is filled with a specified internal pressure,
(1) 50 take-off tests with 100% specified load,
(2) 8 taxi tests with 100% specified load
(3) Two taxi tests with 120% specified load,
(4) Takeoff test with 120% specified load 5 times,
And passed if no failure was completed.

  As a result, the tire according to the example completed running and no abnormality was observed even in the non-destructive inspection after the test, whereas in the tire according to the comparative example, the shoulder portion swollen in (2) and ( In 4), a tread peel-off starting from the end of the endless ply was generated, and the test was stopped. On the other hand, although the conventional tire completed, abnormalities were found in the nondestructive inspection after the test.

(Abrasion test with drum tester)
In this test, a conventional tire, a tire according to a comparative example, and a tire according to an example similar to those shown in Table 1 above were used, and a specified internal pressure, a normal load with a normal load, a lateral force, and a braking force were applied. In this state, it was run on a drum having a file surface, and the running time until the outermost ply was exposed at the shoulder portion was measured.

  As a result, the running time of the tire according to the example was “120”, whereas the running time of the tire according to the comparative example was “119”. This numerical value is indicated as an index with the running time of the conventional tire as “100”, and the larger the value, the longer the running time until exposure and the better the uneven wear resistance.

1 is a cross-sectional view of a high-speed heavy-duty pneumatic radial tire according to an embodiment of the present invention. It is explanatory drawing of the endless belt layer which concerns on one Embodiment of this invention. It is an expanded sectional view of the crown part concerning one embodiment of the present invention.

Explanation of symbols

E: Tire equatorial plane CR: Radius of curvature at the crown center portion ShR: Radius of curvature at the shoulder portion Tw: Ground contact creepage width at the specified internal pressure and specified load 11: Radial tire 12 ... Bead core 13 ... Bead portion 14 ... Side wall portion 15 ... Tread rubber 16a ... down ply 16b ... low turn up ply 16c ... high turn up ply 21 ... carcass layer 22 ... carcass ply 27 ... circumferential groove 29 ... belt layer 31 ... endless ply 31a ... outermost endless ply 32 ... separation ply 33 ... Ribbon 34a, 34b ... Ply end 35 ... Protective layer 36 ... Cord 49 ... Shoulder part 50 ... Crown center part

Claims (3)

A toroid-shaped carcass layer in which a large number of cords substantially perpendicular to the tire equatorial plane are embedded, a tread rubber disposed radially outward of the carcass layer, and between the carcass layer and the tread rubber An endless belt layer composed of a plurality of endless plies arranged and radially stacked, wherein the endless ply intersects the tire equatorial plane at a small angle and bends alternately in opposite directions at both ends of the ply. In the radial tire for high-speed heavy loads in which the cord extending in the tire circumferential direction while being zigzag is embedded almost uniformly in the entire region,
The radius of curvature at the crown center in the region from 35 to 40% of the contact creepage width at the specified internal pressure and specified load relative to the tire equatorial plane is 600 to 720 mm at the specified internal pressure and no load. Yes,
The radius of curvature at the shoulder portion, which is on both sides of the crown center portion and is in the region of 85% to 110% of the ground contact creepage width at the time of the specified internal pressure and specified load with reference to the tire equatorial plane, is the specified internal pressure and no load. A pneumatic radial tire for high speed heavy loads, characterized in that it is 30 to 50 mm in time. The creepage width of the outermost endless ply is at least 1.01 times the ground creepage width at the specified load and specified internal pressure.
The creepage width of the endless ply of the outermost layer is 1.05 times the distance from the tire equatorial plane to the intersection of the normal line at the ground contact edge on the tire surface at the specified internal pressure and specified load and the endless ply of the outermost layer. The high-speed heavy-duty pneumatic radial tire according to claim 1, which is as described above. The endless belt layer is substantially parallel to the surface of the tread rubber in a region from the tire equator surface to 70 to 75% of the ground contact creepage width at the specified internal pressure and specified load with reference to the tire equator surface. The pneumatic radial tire for high-speed heavy loads according to claim 1.

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