TIRE WITH SPECIFIED CORD CONSTRUCTION

Abstract

A cord reinforces a rubber article. The cord includes a core strand having a two-layer twisted layer structure formed by intertwining a plurality of filaments, a plurality sheath strands intertwined around the core strand, the sheath strands having a twisted layer structure formed by intertwining a plurality of filaments, and a wrap wire applied around the core strand and at least one of the sheath strands. The wrap wire creating a permanent and stable minimum gap between the core strand and the sheath strands.

Claims

1. A cord for reinforcing a rubber article comprising: a core strand having a two-layer twisted layer structure formed by intertwining a plurality of filaments; a plurality sheath strands intertwined around the core strand, the sheath strands having a twisted layer structure formed by intertwining a plurality of filaments; and a wrap wire applied around the core strand and at least one of the sheath strands, the wrap wire creating a permanent and stable minimum gap between the core strand and the sheath strands.

2. The cord as set forth in claim 1 wherein the plurality of sheath strands includes between 4 and 8 sheath strands.

3. The cord as set forth in claim 1 wherein the core strand has a 1+6 structure with the core of the core strand comprising one core filament and six sheath filaments being intertwined around the core of the core strand to form a sheath.

4. The cord as set forth in claim 1 wherein each sheath strand has a 1+6 structure with a core of the sheath strand comprising one core filament and six sheath filaments being intertwined around the core of the sheath strand to form a sheath.

5. The cord as set forth in claim 1 wherein each filament forming the core strand has an identical diameter.

6. The cord as set forth in claim 1 wherein a diameter of the cord is 4 mm or greater.

7. The cord as set forth in claim 1 wherein a diameter of the cord is less than 5 mm.

8. The cord as set forth in claim 1 wherein the rubber article is a tire.

9. A tire comprising: two bead structures; a carcass extending from one bead structure to the other bead structure; a belt disposed radially outward from the carcass; a tread for engaging a road surface; and a cord including a core strand having a two-layer twisted layer structure formed by intertwining a plurality of filaments, a plurality sheath strands intertwined around the core strand, the sheath strands having a twisted layer structure formed by intertwining a plurality of filaments, and a wrap wire applied around the core strand and at least one of the sheath strands, the wrap wire creating a permanent and stable minimum gap between the core strand and the sheath strands.

10. The tire as set forth in claim 9 wherein the plurality of sheath strands includes between 4 and 8 sheath strands.

11. The tire as set forth in claim 9 wherein the core strand has a 1+6 structure with the core of the core strand comprising one core filament and six sheath filaments being intertwined around the core of the core strand to form a sheath.

12. The tire as set forth in claim 9 wherein each sheath strand has a 1+6 structure with a core of the sheath strand comprising one core filament and six sheath filaments being intertwined around the core of the sheath strand to form a sheath.

13. The tire as set forth in claim 9 wherein each filament forming the core strand has an identical diameter.

14. The tire as set forth in claim 9 wherein a diameter of the cord is 4 mm or greater.

15. The tire as set forth in claim 9 wherein a diameter of the cord is less than 5 mm.

16. The tire as set forth in claim 9 wherein the wrap wire in constructed of steel.

17. The tire as set forth in claim 9 wherein the wrap wire in constructed of a polymer.

18. The tire as set forth in claim 9 wherein the wrap wire in constructed of nylon.

19. The tire as set forth in claim 9 wherein the wrap wire in constructed of polyester.

20. The tire as set forth in claim 9 wherein the wrap wire in constructed of aramid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0105] The present invention will be described with reference to the accompanying drawings, wherein:

[0106] FIG. 1 is a schematic cross-section view of an example tire for use with the present invention; and

[0107] FIG. 2 is a schematic cross-section view of a cord in accordance with the present invention.

DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0108] The following language is of the best presently contemplated example mode or modes for carrying out the present invention. This description is made for the purpose of illustrating the general principals of the present invention and should not be interpreted as a limitation of the appended claims. The scope of the present invention may be best determined by reference to the appended claims. As a supplement to the description below, U.S. Pat. Nos. 6,412,534 and 7,104,299 are hereby incorporated by reference in their entirety.

[0109] Referring to FIG. 1, a tire, pneumatic or non-pneumatic, for use with the present invention may include a pair of bead portions 1, a pair of sidewall portions 2, a tread portion 3 extending between each sidewall portion 2, a carcass 5 of one or more plies (one ply in FIG. 1) extending between a pair of bead cores 4 embedded in the bead portions 1 to reinforce the bead, sidewall, and tread portions 1, 2, 3, and a belt 6 reinforcing the tread portion 3 on the outer circumference of the carcass 5. The carcass 5 and belt 6 may include a rubberized ply of multiple cords 100. The belt 6 may include at least two rubberized steel wire element layers (3 shown in FIG. 1). Each cord 100 may be formed of a metal, such as steel, titanium, aluminum, etc., and/or organic fibers, such as an aromatic polyamide fiber, a nylon fiber, a polyester fiber, etc. and/or inorganic fibers, such as carbon fiber, etc., and/or any combination thereof.

[0110] A radially outermost belt layer (e.g., overlay, etc.) 60 of the belt 6 may be a layer(s) containing steel cords/wires or organic cords or inorganic cords 100 arranged between −5 degrees and +5 degrees with respect to an equatorial plane E of the tire. At least one other layer 6M (two layers in FIG. 1) may be located radially inward from the outermost belt layer 60. If steel, the cords 100 may constitute a skeleton of each of the layers 6.sub.O, 6.sub.M of the belt 6 defined by one or more bundles of one or more steel filaments without twisting, and/or one or more steel cords obtained by twisting plural steel filaments, and/or one or more steel monofilaments.

[0111] Multi strand cord reinforcements have been used to reinforce rubber in off the road tires in both plies 5 and belts 6. Conventional tires have used a resin to fill the gap(s) between the inner core strands and outer sheath strands of the multi strand cords 5 or 6 and to optimize the filament crossing angle between the outer sheath strands and the inner core strands. One conventional method has co-extruded a rubber or resin on the inner core strand during cable production. A more robust solution where the gap(s) may be better controlled would be desirable.

[0112] Durability of a tire may be extended if corrosion propagation can be limited. If an external object penetrates to a level of a carcass cord 5 or a belt cord 6, exposing it to oxidation from the service environment, particularly moisture, corrosion may propagate. Depth of rubber penetration may increase when the strands of the multi strand construction have gaps 140 therebetween thereby allowing more rubber to penetrate from and between the outer sheath 130 to the inner core 140 of the strand 100. Such increased rubber penetration may thus decrease exposure of the cords 5, 6 and decrease corrosion following external object penetration.

[0113] In accordance with the present invention, this gap(s) 140 may be advantageously achieved by applying a wrap or gap wire 110, consisting of a fine monofilament around the inner core strand 120 and at least 50 percent of the outer sheath strands 130, as shown in FIG. 2. The wrap wire 110 may be applied at a lay length that is less than the lay length(s) of the strands 130, 140 and may be twisted in the same or opposite direction. The wrap wire 110 may be metallic or polymeric material, such as monofilament steel and/or monofilament polyester. The wrap wire 110 may alternatively be a zinc plated steel cord or a brass plated steel cord with a zinc top coating. The diameter of the wrap wire 110 may be between 0.1 mm and 0.2 mm. The gap wire 110 may thus create a permanent and stable minimum opening/gap 140 between the steel cord strands 120, 130 to maximize the rubber penetration fully to the inner core strand 120. Once the tire is vulcanized, this gap wire 110 may provide no further structural support, and the improvement in durability from the added rubber penetration may exceed any potential deleterious effects of the gap wire 110. Increased rubber penetration may also increase the impact resistance of the cords 5, 6 as rubber between the cord strands 120, 130 may reduce stress concentrations at rubberless, empty gaps between strands 120, 130. A gap wire 110 in accordance with the present invention may also simplify wire manufacturing, eliminating addition of resins or compounds, and achieve a more robust solution where the gap 140 may be better controlled/maintained.

[0114] Variations in the present invention are possible in light of the description of it provided herein. While certain representative examples and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes, modifications, equivalents may be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes may be made in the particular examples described herein which will be within the fully intended scope of the present invention as defined by the following appended claims.