IL44993A - Pneumatic tire with reinforced carcass and tread - Google Patents

Abstract

1477210 Pneumatic tyres MICHELIN & CIE (COMPAGNIE GENERALE DES ETABS MICHELIN) 11 June 1974 [12 June 1973] 25912/74 Heading B7C A pneumatic tyre comprises at least one parallel cord carcass ply, the cords of which form an angle of 70 to 90 degrees with the circumferential direction in the sidewalls and in the crown a smaller angle with the circumferential direction, and three superposed oblique parallel cord breaker plies making respective angles with the circumferential direction, wherein the direction of the cords of the breaker ply next adjacent the carcass differs by at most approximately 30 degrees from the perpendicular to one diagonal of a parallelogram with sides parallel to the cords of the other two breaker plies, the other diagonal being parallel to the circumferential direction. As illustrated in Fig. 3, angles α, #, γ are + 23, - 16, and + 31 degrees respectively. The embodiment of Figs. 4 and 5 comprises a rayon cord carcass ply 1, and a breaker consisting of a rayon cord ply 53, a polyvinyl alcohol cord ply 4, and a steel cord ply 5. Initially the plies are wound in a cylindrical drum with cord angles #=80 degrees (the carcass ply has same cord angle over its whole width prior to shaping), α= +38, #= -31, γ= + 73 degrees. After shaping (with the tyre diameter being 1À5 times the diameter of the cylindrical blank) the cord angles were #= -55¢, α= +23, # = - 16, and γ= +31 degrees. Rubber strips 55 are positioned beneath folded edges 54. [GB1477210A]

Claims (14)

• I CLAIM:

1. A pneumatic tire comprising a crown, a pair of sidewalls . extending inwardly from opposite edges of the crown, a pair of beads at the inner edges of the sidewalls, and a reinforcement, the reinforcement comprising, proceeding in a direction from the inside towards the outside of the tire, a carcass reinforcement comprising at least one ply of cords continuous from one to the other of the beads and forming with the circumferential direction an angle between 70° and 90° in the sidewalls and, in the region of the crown, an angle smaller than the angle formed by the cords of the carcass reinforcement in the sidewalls, and three superimposed plies of cords in the region of the crown, the cords of the three crown plies forming acute angles a, 3 and γ, respectively, with the circumferential direction, the cord angle a of the one of the three crown plies nearest the carcass reinforcement being such that the expression tan β - tan γ - 2 tan a tan β tan γ 2 tan 3 tan γ + tan a (tan 3 - tan γ) is, in absolute value, less than 0.6.

2. A tire according to claim 1 wherein the cord angle a differs by at most 30° from the perpendicular to a diagonal of a unit parallelogram, the unit parallelogram having sides parallel to the cords of the other two of the three crown plies, the diagonal intersecting a unit diagonal of the parallelogram, and the unit diagonal being parallel to the circumferential direction of the tire.

3. A tire according to claim .1 wherein tan a is substantially equal to tan β - tan γ 2 tan β tan γ

4. A tire according to claim 1 wherein the cords of the other two of the three crown plies form with the circum ferential direction angles less than 45°.

5. . 5. A tire according to claim 1 wherein the cords of the other two of the three crown plies form with the circum ferential direction angles between 15° and 35°.

6. A tire according to claim 1 comprising means reinforcing the edges of the crown reinforcement constituted by the three crown plies.

7. A tire according to claim 1 wherein the cords of the one of the three crown plies nearest the carcass reinforcement have a total cross sectional area per unit of ply width which is less than that of the cords of the other plies present in the region of the crown.

8. A tire according to claim 1 wherein the one of the three crown plies nearest the carcass reinforcement is narrower than the other two of the three crown' lies.

9. A tire according to claim 8 wherein the width of the one of the three crown plies nearest the carcass reinforcement is between 50% and 90% of the average width of the other two of the three crown plies.

10. A tire according to claim 8 wherein the width of the one of the three crown plies nearest the carcass reinforcement is between 70% and 75% of the average width of the other two of the three crown plies.

11. A tire according to claim 8 comprising rubber inserts between the carcass reinforcement and the portion of the other two of the three crown plies that overhang the one of the three crown plies nearest the carcass reinforcement.

12. A cylindrical blank for the manufacture of a pneumatic tire formed with a crown and pair of beads spaced apart from the crown, comprising a reinforcement , the reinforcement comprising, proceeding in a direction from the inside towards the outside of the blank, a carcass reinforcement comprising at least one ply of cords continuous from one to the other of the beads and forming with the circumferential direction over at least part of their length an angle between 70° and 90°, and three superimposed plies in the region of the crown, the cords of the three crown plies forming acute angles α, β, and γ, respectively, with the circumferential direction, the cord angle a of the one of the three crown plies nearest the carcass reinforcement being such that the expression tan β - tan γ - 2 tan a tan β tan γ 2 tan β tan γ + tan a (tan β - tan γ) is, in absolute value, less than 0.6.

13. - Λ cylindrical blank according to claim 12 wherein the cords of the carcass ply form an angle δ with the circumferential direction in the region of the crown plies, the cord angle δ being such that the expression tan a + tan 5 tan β + tan γ is at least equal to 1.

14. A cylindrical blank according to claim 12 wherein the cords of the carcass ply form an angle δ with the circumferential direction in the region of the crown plies, the cord angle δ being such that the expression • tan a + tan δ tan 3 + tan γ is betwee 1 and 4. For the Applicants Dr. Yitzhak Hess