Pneumatic tire with reinforcing belt that minimizes belt end gyroscopic effect

Abstract

The pneumatic tire incorporates a reinforcement belt comprising two superposed median plies of metallic material and two laterally disposed marginal plies of nonmetallic material. The marginal plies are folded to form superposed flaps, with the corresponding flaps of each marginal ply being substantially aligned.

In all embodiments of the invention at least one pair of corresponding opposite, laterally disposed flaps align with one of the median plies. In at least one embodiment of the invention the second pair of opposite, laterally disposed flaps align with the second median ply. In other embodiments of the invention the second pair of opposite, laterally disposed flaps overlap the terminal ends of the second median ply. And in still further embodiments of the invention the second pair of opposite, laterally disposed flaps are positioned radially outward or radially inward of the second median ply. In all embodiments of the invention there are at least two and at the most three layers of ply material at various points along the crosswise width of the reinforcing belt.

Description

The present invention relates to pneumatic tires and more particularly to a pneumatic tire having an improved reinforcement belt construction.

The invention is especially applicable to radial carcass pneumatic tires. The term radial, as used herein, refers to directions perpendicular to the axis of rotation of the tire, and the term crosswise refers to directions parallel to said axis.

Tires having reinforcement belts are well known and generally include one or more plies of rubberized fabric reinforced with parallel filaments, cords or cables. A common type of reinforcement belt generally includes one or more plies incorporating metallic filaments or cables, associated with one or more plies incorporating nonmetallic filaments or cables.

In one known tire construction the reinforcement belt comprises a first pair of laterally spaced plies incorporating metallic cables. The plies are folded and substantially aligned in a crosswise direction with the folded portions forming one lateral crosswise extremity. A second pair of laterally spaced plies incorporating nonmetallic cables are also folded and substantially aligned, with the folded portion forming another lateral crosswise extremity. The first pair of folded plies is superposed with the second pair of folded plies, the folded ends of the second pair extending crosswise beyond the folded ends of the first pair without encompassing or bracketing the first pair.

One of the problems present in this known tire construction is an undesirable gyroscopic effect caused by the belt that adversely affects steering of the tires. This gyroscopic effect, which is attributable in part to a relatively large belt mass at the extreme lateral edges or marginal regions of the reinforcement belt, is especially noticeable during high speed movement of the tires. For example, any rotation of the steering wheel which changes the spin axis of the steered wheels is opposed by a gyroscopic restoring torque that is a function of the angular momentum of the steered wheels.

Another problem present in known tire constructions having reinforcing belts is the tendency of the marginal folds of a ply incorporating metallic cable to separate from the tread. The likelihood of such breakage can be reduced by using cables having finer wires, strands or filaments, but at considerably more cost than the coarser cable components.

A further problem of known tires with reinforcing belts is a decrease in travelling comfort due to the presence of relatively rigid metallic constituents at the edge portions of the reinforcing belt that can cause the tire to reflect or amplify unsmooth road conditions. This is especially apparent with tires having a reinforcing belt that comprises plies of metallic cables only. Such tires are relatively inadequate in deforming to permit expansion. Moreover the vulcanization and formation of profiles in the tread of such tires often requires complex and expensive molds having multiple segments.

It is thus desirable to provide a pneumatic tire having a reinforcement belt construction that minimizes the problems of gyroscopic effect and belt end separation, yet furnishes improved travel comfort, and is economical to manufacture.

Among the several objects of the invention are the provision of a pneumatic tire having a novel reinforcement belt construction of relatively low belt mass at the marginal edge portions of the reinforcing belt. A pneumatic tire incorporating a novel reinforcement belt construction which minimizes the likelihood of separation between the tread and the plies incorporating metallic cable, and a tire having a reinforcing belt construction that affords improved travelling comfort and is relatively inexpensive to manufacture. Other objects and features will be in part apparent and in part pointed out hereinafter.

The present invention relates to a pneumatic tire wherein an annular reinforcement belt surrounds a carcass intermediate the carcass and the tread in substantially symmetrical relationship to an equatorial plane of the tire. The reinforcement belt, in cross section, comprises two crosswise spaced, opposite, laterally disposed plies of non-metallic material, each folded to form a pair of confronting flap portions having ends directed toward the equatorial plane of the tire. Homologous ends of the flap portions are aligned and have respective predetermined crosswise spacings therebetween.

A first ply of metallic material is disposed intermediate a first pair of opposite, laterally disposed flaps in alignment with the ends of the flaps, enabling the flaps to form terminal extensions of the first ply of metallic material.

A second ply of metallic material, which can be of lesser or greater crosswise extent than the first ply of metallic material, is arranged adjacent the first ply of metallic material to provide at least two and at the most three layers of ply material at various points along the crosswise width of the reinforcing belt. The crosswise extent of the second ply of metallic material is predetermined so as not to extend past the marginal ends of the opposite, laterally disposed plies of nonmetallic material. Under this arrangement the reinforcing belt constituents include two plies of metallic material in the median portion and two plies of nonmetallic material at the marginal end portions.

In at least one embodiment of the invention the second ply of metallic material is disposed intermediate the second pair of opposite, laterally disposed flaps in alignment with the ends of the flaps to form terminal extensions of the second ply of metallic material.

In still other embodiments of the invention only one ply of metallic material is aligned with the ends of one pair of opposite, laterally disposed flaps of nonmetallic material. The second pair of opposite, laterally disposed flaps of non-metallic material are bent over the terminal ends of the second ply of metallic material to form a third layer in the median portion of the reinforcement belt.

The invention also contemplates embodiments wherein the second ply of metallic material is entirely disassociated from the second pair of opposite, laterally disposed flaps of nonmetallic material, the second ply being radially inward or outward of the second pair of flaps to form a third layer in the median portion of the reinforcing belt.

In still another embodiment of the invention one ply of metallic material is substantially aligned with the homologous ends of the first and second pairs of opposite laterally disposed flaps of nonmetallic material. The second ply of metallic material is arranged radially outward of the first ply of metallic material and the folded flaps to form a third layer of the reinforcing belt.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawing in which mediamincludea include a tire having a reinforcementbelt reinforcement belt with relatively lightweight, substantially inextensible marginal edge portions for reducing the undesirable gyroscopic effect and thereby facilitating operation of the steering wheel. The use of Kevlar material or an equivalent substance in the marginal plies renders said plies lightweight and substantially inextensible. The disclosed arrangements of marginal nonmetallic filament plies with median plies of metallic material improves travel confort comfort and minimizes the hazard of belt ply separation at the edges of the tread, since the plies of metallic materal are intermediate the edge portions of the belt, and are not turned up. A further advantage is that there are not less than two plies nor more than three plies of belt material at all points throughout the crosswise extent of the reinforcing belt and no ply surrounds another ply. Moreover the plies of nonmetallic material are not inserted between plies of metallic material, and the plies of metallic material are not inserted between confronting folded portions of the plies of nonmetallic material, making it possible to reduce the number of superposed plies or flaps to a minimum. The disclosed tire construction incorpoarates incorporates a reinforcement belt or of relatively simple design, is economical to maufacture since a two part vulcanization mold can be used, and provides improved operating reliability.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

1. A pneumatic tire comprising an annular carcass having a radially outerlying crown portion, a tread constituting an annular cover surrounding the crown portion of said carcass, and an annular reinforcement belt interpositioned between the crown portion of said carcass and said tread, said reinforcement belt comprising, in cross-section, a pair of opposite, laterally disposed, crosswise spaced, first and second plies of a first cord material, each of said first and second plies being folded to form two respective flap portions having ends directed toward an equatorial plane of the tire and respective folded margins directed away from said equatorial plane, one of the flaps of each said first and second folded ply confronting at least a portion of the other said respective flap, a first ply of second cord material having opposite terminal ends being disposed between homologous ends of one of the pairs of corresponding opposite, laterally disposed flap portions such that said one pair of opposite, laterally disposed flap portions extends laterally beyond corresponding terminal ends of said first ply of second cord material in substantial alignment with said corresponding opposite terminal ends, and a second ply of said second cord material having opposite terminal ends, said second ply of second cord material being disposed adjacent said first ply of second cord material such that said second ply of second cord material does not extend laterally beyond the folded margins or between the confronting flap portions of the first and second folded plies, whereby said first and second plies of the first cord material are positioned at the marginal ends of said reinforcement belt and said first and second plies of the second cord material are positioned at the median portion of the reinforcement belt.

2. A pneumatic tire as claimed in claim 1 wherein said first cord material comprises textile cords and said second cord material comprises metallic wire cords.

3. A pneumatic tire as claimed in claim 2 wherein said textile cord material is formed of a synthetic substance on an aromatic polyamide base identified by the trade name Kevlar.

4. A pneumatic tire as claimed in claim 1 wherein said reinforcement belt is symmetrical with respect to the equatorial plane of said tire.

5. A pneumatic tire as claimed in claim 1 wherein homologous ends of the first and second pairs of corresponding opposite, laterally disposed flaps are crosswise aligned.

6. A pneumatic tire as claimed in claim 1 wherein said first pair of corresponding opposite, laterally disposed flap portions constitute substantially contiguous extension extensions of said first ply of second cord material.

7. A pneumatic tire as claimed in claim 1 wherein the crosswise width of said reinforcement belt has a maximum width of 125% of the tread width.

8. A pneumatic tire as claimed in claim 7 wherein the second ply of second cord material is of a different crosswise extent than the first ply of second cord material, the narrower of said plies of second cord material ranging in size from 50% to 90% of the crosswise width of said tread.

9. A pneumatic tire as claimed in claim 8 wherein the wider of said plies of second cord material ranges in size from a crosswise extent less than said tread width to a crosswise extent greater than said tread width.

10. A pneumatic tire as claimed in claim 1 wherein said second ply of second cord material is of lesser crosswise extent than the crosswise distance from one of the folded margins to the other said folded margin.

11. A pneumatic tire as claimed in claim 1 wherein said second ply of second cord material is disposed between homologous ends of the other pair of corresponding opposite, laterally disposed flap portions such that said other pair of corresponding opposite, laterally disposed flap portions extend crosswise beyond corresponding terminal ends of said second ply of second cord material in substantial alignment with the corresponding terminal ends of said second ply of second cord material.

12. A pneumatic tire as claimed in claim 11 wherein said other pair of corresponding opposite, laterally disposed flap portions constitute substantially contiguous extensions of said second ply of second cord material.

13. A pneumatic tire as claimed in claim 11 wherein the crosswise extent of the first and second plies of second cord material are substantially equivalent.

14. A pneumatic tire as claimed in claim 13 wherein the crosswise extent of said first and second plies of second cord material is within the range of 50% to 90% of the crosswise width of said tread.

15. A pneumatic tire as claimed in claim 11 wherein said frist first ply of second cord material is of greater crosswise extent than the second ply of second cord material.

16. A pneumatic tire as claimed in claim 1 wherein the crosswise extent of each flap portion is substantially equivalent.

17. A pneumatic tire as claimed in claim 1 wherein the crosswise extent of each flap of the other pair of corresponding opposite, laterally disposed flap portions is greater than the crosswise extent of each flap of said one pair of corresponding opposite, laterally disposed flap portions.

18. A pneumatic tire as claimed in claim 17 wherein said second ply of second cord material is disposed between homologous free ends of the other pair of corresponding opposite, laterally disposed flap portions such that said other pair of corresponding opposite, laterally disposed flap portions extend crosswise beyond the corresponding terminal ends of said second ply of second cord material in substantial alignment with the corresponding terminal ends of said second ply of second cord material.

19. A pneumatic tire as claimed in claim 18 wherein the first ply of second cord material is of greater crosswise extent than the second ply of second cord material and is disposed radially inward of the second ply of second cord material.

20. A pneumatic tire as claimed in claim 18 wherein the first ply of second cord material is of lesser crosswise extent than the second ply of second cord material and is disposed radially inward of the second ply of second cord material.

21. A pneumatic tire as claimed in claim 17 wherein said one pair of corresponding opposite, laterally disposed flap portions is disposed radially outwardly of said other pair of corresponding opposite, laterally disposed flap portions.

22. A pneumatic tire as claimed in claim 21 wherein the second ply of second cord material is of greater crosswise extent than the first ply of second cord material and is disposed radially outward of the first ply of second cord material.

23. A pneumatic tire as claimed in claim 20 wherein the crosswise extent of each flap of the other pair of corresponding opposite, laterally disposed flap portions is approximately one-half the crosswise distance between said folded margins.

24. A pneumatic tire as claimed in claim 17 wherein each flap of said one pair of corresponding opposite, laterally disposed flap portions is disposed radially inward of said other pair of corresponding opposite, laterally disposed flap portions.

25. A pneumatic tire as claimed in claim 24 wherein the second ply of second cord material is of greater crosswise extent than the first ply of second cord material and is disposed radially inward of the first ply of second cord material.

26. A pneumatic tire as claimed in claim 17 wherein each flap of the other pair of corresponding opposite, laterally disposed flap portions overlaps the terminal ends of one of the plies of second cord material.

27. A pneumatic tire as claimed in claim 26 wherein the crosswise width of said overlap is at least 10% of the tread width.

28. A pneumatic tire as claimed in claim 17 wherein said second ply of second cord material is of greater crosswise extent than the crosswise space between homologous free ends of said other pair of corresponding opposite, laterally disposed flap portions, said other pair of corresponding opposite, laterally disposed flap portions being folded over the terminal ends of said second ply of second cord material and being substantially coplanar with said second ply of second cord material between the folded over portion and the folded margins.

29. A pneumatic tire as claimed in claim 28 wherein said second ply of second cord material is of lesser crosswise extent than said first ply of second cord material.

30. A pneumatic tire as claimed in claim 29 wherein said second ply of second cord material is disposed radially outward of said first ply of second cord material.

31. A pneumatic tire as claimed in claim 29 wherein said second ply of second cord material is disposed radially inward of said first ply of second cord material.

32. A pneumatic tire as claimed in claim 31 wherein the crosswise extent of each flap of said other pair of corresponding opposite, laterally disposed flap portions is approximately one-half the crosswise distance between said folded marginal ends.

33. The pneumatic tire as claimed in claim 32 wherein the ends of said other pair of opposite, laterally disposed flap portions form a butt joint substantially at said equatorial plane.

34. A pneumatic tire as claimed in claim 16 wherein said other pair of corresponding opposite, laterally disposed flap portions extend crosswise beyond the corresponding terminal ends of said first ply of second cord material in substantial alignment with said corresponding opposite terminal ends, said second ply of second cord material being disposed radially outward of said first and second folded plies and said first ply of second cord material.