WO2008063178A1

WO2008063178A1 - Tire with improved bead portion

Info

Publication number: WO2008063178A1
Application number: PCT/US2006/045308
Authority: WO
Inventors: Robert C. Lawson; Daniel R. Rey
Original assignee: Michelin Recherche Et Technique S.A.; Societe De Technologie Michelin
Priority date: 2006-11-22
Filing date: 2006-11-22
Publication date: 2008-05-29

Abstract

A tire includes bead portions (300) that each have a bead ply (350) encompassing a profile (345) and then turning around a bead core (310). One or more carcass layers (365, 375) are extended into each bead portion (300). A method of manufacturing the tire includes preparing an intermediate comprising the bead ply (350) and the profile (345) prior to tire construction on an assembly drum.

Description

TITLE

TIRE WITH IMPROVED BEAD PORTION

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a tire having an improved bead portion that also provides advantages in manufacturing the tire, hi general, the tire includes bead portions that each have a bead ply encompassing a profile and then turning around a bead core. One or more carcass layers are extended into each bead portion. The present invention also provides for an improved manufacturing method in which an intermediate comprising the bead ply and the profile can be prepared prior to tire construction on an assembly drum.

BACKGROUND OF THE INVENTION

[0002] U.S. Patent No. 5,971,047 describes an exemplary embodiment of a unique tire design in which a carcass layer is wrapped around a profile located adjacent to the bead core. More specifically, in the exemplary embodiment of Fig. 2 of such patent, a bead portion is described in which the carcass completely surrounds a profile located adjacent to the bead core. The carcass wraps around the outside of the profile and then turns up around the bead core such that the turn-up end of the carcass is located radially above, and axially inside the bead core. Another variant that includes a wrapped profile is shown in Fig. 4 for example. [0003] Challenges are encountered when manufacturing a bead portion have a profile analogous to the profile described in U.S. Patent No. 5,971,047. Equipment and techniques have been proposed for accomplishing the step by which the carcass is wrapped around the profile and then turned up around the bead core. For example, U.S. Patent No. 6,250,356 describes such an assembly drum and method for tire manufacture. As shown in Figs. 6A through 6H of this patent, the wrapping of the carcass reinforcement ends about the bead profiles is a multi-step process. In general, each end of the carcass reinforcement is positioned over a support element having a bearing groove or depression in its radial outermost surface. Along each end, a profile is positioned over the carcass reinforcement. Lifting fingers, located along each side of the assembly drum, are actuated so as to lift the carcass reinforcement ends in a manner that begins the maneuver of wrapping the carcass around the profile. Guide wires, carrying the bead cores, are advanced axially inward along the drum to engage the ends of the carcass reinforcement and further turn the ends around the profiles. Then, the advancement of the guide wires is synchronized with the expansion of the drum so that along each side of the carcass reinforcement, the profile and bead are moved into a respective bearing groove in a manner that completes the wrapping of the carcass reinforcement end around the profile while also turning up the carcass reinforcement end around the bead core.

[0004] The present invention provides an improved tire structure that may be constructed according to an inventive method that eliminates certain maneuvers previously undertaken on the tire assembly drum. More specifically, the present invention provides a unique and improved tire structure that allows a manufacturer to avoid the process of wrapping a carcass reinforcement about a profile and the turning up the carcass reinforcement end about a bead core using a tire assembly drum. As will be described below, an inventive intermediate is employed that allows elimination of one or more such steps during the process of manufacturing a tire on the assembly drum.

SUMMARY OF THE INVENTION

[0005] Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0006] hi one exemplary embodiment of the present invention, a that defines axial and radial directions is provided. The tire includes a crown portion having a tread, a belt package located radially inward of the tread, and an innerliner portion formed on an interior surface of the tire. A pair of bead portions are included that are axially spaced apart, each bead portion comprising a bead core and a bead filler. This exemplary tire also has a pair of axially spaced apart sidewall portions, where each sidewall portion is disposed radially between a respective axial edge of the crown portion and a respective bead portion. A first carcass layer is disposed radially inward of the belt package near the crown portion of the tire and axially inward of each of the pair of sidewall portions along the sides of the tire. The first carcass layer extends between the pair of bead portions and has a pair of first carcass layer ends. Each first carcass layer end is positioned within a respective bead portion radially inward of a respective bead core. The tire includes a pair of fill portions with each fill portion being located in a respective bead portion at a position that is axially outward and radially inward of a respective bead core. On each side of the tire, a bead ply encompasses each fill portion but not a respective bead core. Each bead ply also extends from a respective fill portion in a manner that is radially inward of and around a respective bead core and then along a radially outward direction. Each bead ply has a bead ply inside end and a bead ply outside end. Each bead ply inside end is positioned radially outward and axially inward of a respective bead ply outside end.

[0007] Other variations of this exemplary embodiment are within the scope of the present invention as well. For example, a second carcass layer may be provided, with such layer being disposed radially inward of the belt package and axially inward of each of the pair of sidewall portions. The second carcass layer extends between a pair of bead portions while remaining radially outward of each of the bead cores. The second carcass layer has a pair of second carcass layer ends, wherein each of the ends is positioned radially outward of a respective bead core along each side of the tire. In certain embodiments, the second carcass layer may be disposed axially inward of the first carcass layer along each respective bead portion.

[0008] Each of the bead plies may be positioned adjacent to a respective first carcass layer in the respective pair of bead portions, with each bead ply inside end extending radially outward of a respective bead ply outside end by a distance that is in a range of about 5 mm to about 8 mm. Additionally, each of the bead ply inside ends may extend radially outward of a respective second layer carcass end by a distance that is in a range of about 5 to about 10 mm. Each first carcass layer end may have a portion that is located radially inward of each radially inside end with such portion having a length that is in a range of about 30 mm to about 35 mm. Each bead ply inside end may extend past the outermost edge of a respective bead core by a distance that is in a range of about 5 mm to about 8 mm. This exemplary embodiment of the present invention may also include a pair of bead cradle strips, each strip being located between a respective bead core and a respective bead ply. Each bead ply outside end may extend radially outward and past the outermost edge of a respective bead core. Each of the first carcass ply ends may be located radially inward of the center-of a respective bead core. [0009] In another exemplary embodiment of the present invention, a tire defining axial and radial directions is provided. The tire has two sides that are axially displaced from each other. The tire includes a crown portion having a tread, an innerliner portion formed on an interior surface of the tire, and a pair of bead portions with one located on each side of the tire. Each bead portion comprises a bead core. A pair of sidewall portions are included with one on sidewall portion located on each side of the tire, wherein each sidewall portion is disposed radially between a respective edge of the crown portion and a bead portion. A first carcass layer is disposed radially inward of the tread and axially inward of the pair of sidewall portions. The first carcass layer extends between the pair of bead portions and has a pair of first carcass layer ends, wherein on each side of the tire the first carcass layer end is positioned within a respective bead portion at a location that is radially inward of the bead core. A pair of bead plies is provided, with one located on each side of the tire in a respective bead portion, each bead ply being wrapped around a profile that is located axially outward of a bead core. Each bead ply extends axially inward from a profile to an intermediate position that is between a bead core and a first carcass layer end. Each bead ply then extends radially outward from the intermediate position into an inside bead ply end and an outside bead ply end with both such bead ply ends being located within a respective bead portion. Each inside bead ply end extends radially outward of a respective bead ply outside end by a distance in a range of about 5 to about 8 mm. The first carcass layer, on each side of the tire, has a length located radially inward of a the inside bead ply end that is in a range of about 30 mm to about [0010] The present invention also includes methods of building a tire. For example, in one such method, a tire is constructed by steps that include applying a carcass material to a drum surface, the carcass material having a pair of sides. A tire intermediate is placed on each side of the carcass material, each tire intermediate comprising a fill portion wrapped in a bead ply, the bead ply having an inside end and an outside end, wherein the inside extends past the outside end. A bead core is presented over each side of the carcass material and adjacent the intermediate at a position that is between the fill portion and the inside and outside ends of the bead ply. Each bead core is then wrapped at least partially within the tire intermediate. If desired, this inventive process may further include the step of positioning a bead cradle strip against the manufacturing intermediate on each side of the carcass material before presenting the bead core. The present invention also includes a tire constructed according to such exemplary method.

[0011] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0013] Fig. 1 is a cross-sectional view of the bead portion of a tire constructed according to an exemplary embodiment of the present invention in which a single carcass layer is used.

[0014] Fig. 2 is a cross-sectional view of the bead portion of a tire constructed according to an exemplary embodiment of the present invention in which two carcass layers are present with a shorter, second carcass layer being positioned axially outward of a longer, first carcass layer.

[0015] Fig. 3 is a cross-sectional view of the bead portion of a tire constructed according to an exemplary embodiment of the present invention in which two carcass layers are present with a longer, first carcass layer being positioned axially outward of a shorter, second carcass layer.

[0016] Figs. 4A through 4D depict an exemplary method of the present invention. Portions is a tire assembly drum are illustrated during certain steps of the exemplary method. [0017] Repeat use of identical or similar reference characters throughout the present specification and appended drawings is intended to represent same or analogous features or elements of the invention. Enlarged dots are used in the drawings to help denote lengths as discussed in the specification and do not, by themselves, represent structure within the tire. More specifically, L₁, L₂, and L₃ each denote a length that falls between two dots along one or more components of exemplary embodiments of the invention as discussed below. In each figure, arrow R represents a direction that is radially outward while arrow A indicates a direction that is axially inward.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention provides for improved constructions for the bead portions of a tire. The improved constructions provides desirable performance benefits while allowing for improvements in manufacturing. Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the figures. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations. It should be noted that for the purposes of discussion, only half of the exemplary tire embodiments may be depicted in one or more of the figures. One of ordinary skill in the art, using the teachings disclosed herein, will understand that the same or substantially similar features are repeated on both sides of the tire. Exemplary embodiments of the invention will be described along with illustrations of cross sections of bead portions and partial sidewall portions along one side of exemplary tires, it being understood that similar constructions are used on both sides of a tire.

[0019] Fig. 1 illustrates a bead portion 100 and part of a sidewall portion 135 along one side of a tire constructed according to an exemplary embodiment of the present invention. Sidewall portion 135 is constructed from a rubber material that typically covers the outer surface of the tire and protects the carcass layers and other reinforcing members from damage. Rim strip 140 makes up the outer component of bead portion 100 and provides a rubber material that is shaped in part for the receipt of a rim or wheel onto which the tire having bead portion 100 will be mounted. Rim strip 140 wraps around various bead components that will be described, including bead core 110 and bead filler 130, to meet with an inner liner 125, which is constructed of an air impermeable material to retain air pressure within the tire.

[0020] By way of example only, rim strip 140 is constructed from a material having a Modulus of Elasticity at ten percent unit strain with a value in the range of about 5 MPa to about 15 MPa. By way of further example, bead filler 130 is constructed from a material having a Modulus of Elasticity at ten percent unit strain with a value in the range of about 10 MPa to about 40 MPa. However, the rubber in bead filler 130, sidewall portion 135, and rim strip 140 can be constructed of any suitable rubber compound based on natural or synthetic rubber or any suitable combination thereof known in the art. Inner liner 125 can be constructed of any suitable material and is preferably constructed of a halobutyl rubber. Bead core 110, which provides a substantially inextensible member for mounting the tire to a rim, is typically constructed from metal wires grouped into a bundle.

[0021] Bead portion 100 includes a carcass ply 165 having a carcass ply end 170 that is located at a position that is radially inward of bead core 110. Carcass ply 165 extends between axially spaced-apart bead portions 100 located on both sides of the tire and is positioned radially inward of the tread and any belts in the crown region and axially inward of sidewall portion 135 on both sides of the tire. Carcass ply 165 can be made of any suitable materials including, by way of example only, various textile materials. For example, ply 165 may be constructed as a composite of rubber and cords made from polyester, nylon, or rayon. As stated, carcass ply end 170, one on each side of the tire, is positioned radially inward of core 110 such that the radial distance Y₃ between the center 105 of core 110 and carcass ply end 170 is always greater than zero.

[0022] A bead ply 150 is also located within bead portion 100. As illustrated in Fig. 1 , bead ply 150 wraps around a fill portion or profile 145. The profile 145 is located at a position that is axially outward and radially inward of bead core 110 and appears partially shaped to the circumference of bead core 110. Bead ply 150 encompasses, or wraps around, profile 145, curves around core 110 and then extends radially outward into a pair of ends including bead ply outside end 155 and bead ply inside end 160. Bead ply 150 may be constructed of a variety of suitable materials including, by way of example, composites of rubber and cords made from polyester, nylon, or rayon. Profile 145 may be constructed from any suitable rubber materials. For example, profile 145 may be constructed from a material having a Modulus of Elasticity at ten percent unit strain with a value in the range of about 50 MPa to about 60 MPa.

[0023] Both bead ply ends 155 and 160 extend radially past the outer circumference of bead core 110. More specifically, for this exemplary embodiment, distance Y₁ is in a range of about 5 mm to about 8 mm while Y₂ is greater than zero. Additionally, bead ply inside end 160 preferably extends radially outward of bead ply outside end 155 by a distance L₁ that is in a range of 5 mm to about 8 mm. Carcass ply 165 has a length L₂ that is shown to be the length of ply 165 that is located radially inward of bead ply inside end 160. Preferably, L₂ is in a range of about 30 mm to about 35 mm. Finally, cradle strip 115 is positioned between bead core 110 and the portion of bead ply 150 that wraps around core 110. As such, cradle strip 115 provides protection of ply 150 from the inextensible components of core 110. Cradle strip 115 may be constructed from any suitable rubber materials. For example, cradle strip 115 may be constructed from a material having a Modulus of Elasticity at ten percent unit strain with a value in the range of about 5 MPa to about 15 MPa [0024] The structure of bead portion 100 provides certain manufacturing advantages. As will now be described, the preparation of an intermediate structure off-line, i.e. before positioning on the assembly drum, allows a manufacturer to avoid undertaking the turning up of the carcass layer about a profile while on the assembly drum itself. For example, using the exemplary embodiment of a bead portion 100 for illustration and referring to Figs. 4A through 4D, carcass 165 is placed on support elements 400 and 405 of an assembly drum (Fig. 4A). Rather than attempting to turn the ends 170 about profile 145, an already assembled manufacturing intermediate 166 is placed on carcass 165 (Fig. 4B). The intermediate comprises bead ply 150 that has already been wrapped about profile 145 with ends 155 and 160 appropriately positioned relative to one another as previously described. The ends (not shown) of the intermediate 166 are then joined by, for example, an angle-joint or a butt-joint on the assembly drum so that intermediate 166 is secured around the drum. For each side, a bead core 110 is then presented to the assembly drum by guide wire 410 at a position that is between the profile 145 and the ends 155 and 160 of the bead ply (Fig. 4C). The assembly drum is expanded (arrow A) and the intermediate 166 is then molded about the bead core 110 (Fig. 4D). Where desired, the intermediate 166 can also be provided with cradle strip 115 already in place on bead ply 150. Alternatively, as an additional step., after carcass 165 and intermediates 166 have been placed upon the assembly drum, cradle strips 115 can be placed upon each intermediate 166 on both sides of carcass 165 before positioning bead core 110. Thus, using the present invention, difficulties in turning carcass layer 165 about profile 145 are avoided.

[0025] The present invention includes numerous other embodiments which also provide analogous advantages for manufacturing. By way of example, Fig. 2 illustrates a bead portion 200 that includes a bead ply 250 turned about a bead core 210 in a manner similar to that described with regard to the exemplary embodiment of Fig. 1. A first carcass ply 265 extends between the bead portions 200 of the tire and has a pair of first carcass ply ends 270, each of which is positioned radially inward of bead core 210. Other components of bead portion 200 are present in a manner similar to that described with reference to Fig. 1. Bead portion 200 additionally includes a second carcass layer 275 that is located axially outward of first carcass ply 265. Second carcass layer 275 provides additional reinforcement of the tire and may be constructed from a variety of suitable materials as previously described. Second carcass layer 275 terminates in a second carcass layer end 280. As shown in Fig. 2, second carcass layer end 280 extends radially inward past bead ply inside end 260 by an amount L₃. Preferably, L₃ is in a range of about 5 mm to about 10 mm. Dimensions L₁, L₂, Y₁, Y₂, and Y₃ are preferably of a manner as previously described with regard to the exemplary embodiment of Fig. 1.

[0026] As described, in the exemplary embodiment of Fig. 2, second carcass layer 275 was positioned between first carcass layer 265 and bead ply 250. The axial position of second carcass layer 275 may be switched with first carcass layer 265. For example, Fig. 3 illustrates another exemplary embodiment of the present invention having bead portion 300. Here, first carcass layer 365 also extends between bead portions on opposite sides of the tire with each one of a pair of first carcass layer ends 370 being positioned radially inside of a respective bead core 310. For this embodiment, a second carcass layer 375 is positioned axially inside of first carcass layer 365 to a position between layer 365 and inner liner 325. Dimensions L₁, L₂, L₃, Y₁, Y₂, and Y₃ are preferably of a manner as previously described with regard to the exemplary embodiment of Fig. 1.

[0027] Numerous embodiments of the present invention exist within the ranges and values previously described for L₁, L₂, L₃, Y₁, Y₂, and Y₃, and each falls within the scope of the claims that follow, hi addition, each of the exemplary embodiments described with regard to Figs. 1 through 3 allow for the preparation of a manufacturing intermediate, as previously described, that allows the avoidance of problems with turning up a carcass layer. It should be understood that the present invention includes various modifications that can be made to the exemplary embodiments of apparatus and method described herein that come within the scope of the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A tire defining axial and radial directions, the tire comprising: a crown portion having a tread; a belt package located radially inward of said tread; an innerliner portion formed on an interior surface of the tire; a pair of bead portions axially spaced apart, each said bead portion comprising a bead core and a bead filler; a pair of axially spaced apart sidewall portions, wherein each said sidewall portion is disposed radially between a respective axial edge of said crown portion and a respective said bead portion; a first carcass layer disposed radially inward of said belt package and axially inward of each of said pair of sidewall portions, said first carcass layer extending between said pair of bead portions, said first carcass layer having a pair of first carcass layer ends, wherein each said first carcass layer end is positioned within a respective said bead portion radially inward of a respective said bead core; a pair of fill portions, each fill portion being located in a respective said bead portion at a position that is axially outward and radially inward of a respective said bead core; and a pair of bead plies, each said bead ply encompassing a respective said fill portion but not a respective said bead core, each said bead ply also extending from a respective said fill portion in a manner that is radially inward of and around a respective said bead core and then along a radially outward direction, each said bead ply having a bead ply inside end and a bead ply outside end, wherein each said bead ply inside end is positioned radially outward and axially inward of a respective said bead ply outside end.

2. The tire of claim 1 , further comprising a second carcass layer disposed radially inward of said belt package and axially inward of each of said pair of sidewall portions, said second carcass layer extending between said pair of bead portions while remaining radially outward of each said bead core, said second carcass layer having a pair of second carcass layer ends, wherein each of said pair of second carcass layer ends is positioned radially outward of a respective said bead core.

3. The tire of claim 2, wherein said second carcass layer is disposed axially inward of said first carcass layer along each respective said bead portion.

4. The tire of claim 3, wherein each of said pair of bead plies is positioned adjacent to a respective said first carcass layer in said pair of bead portions, with each said bead ply inside end extending radially outward of a respective said bead ply outside end by a distance that is in a range of about 5 mm to about 8 mm

5. The tire of claim 4, wherein each of said bead ply inside ends extends radially outward of a respective said second layer carcass end by a distance that is in a range of about 5 to about 10 mm.

6. The tire of claim 5, wherein for each said first carcass layer end, the length of said first carcass layer that is located radially inward of each said radially inside end is in a range of about 30 mm to about 35 mm.

7. The tire of claim 6, wherein each said bead ply inside end extends past the outermost edge of a respective said bead core by a distance that is in a range of about 5 mm to about 8 mm.

8. The tire of claim 7, further comprising a pair of bead cradle strips, each said strip being located between a respective said bead core and a respective said bead ply.

9. The tire of claim 8, wherein each said bead ply outside end extends radially outward and past the outermost edge of a respective said bead core.

10. The tire of claim 9, wherein each of said first carcass ply ends are located radially inward of the center of a respective said bead core.

11. A tire defining axial and radial directions, the tire having two sides that are axially displaced from each other, the tire comprising: a crown portion having a tread; an innerliner portion formed on an interior surface of the tire; a pair of bead portions with one located on each side of the tire, each said bead portion comprising a bead core; a pair of sidewall portions with one located on each side of the tire, wherein each said sidewall portion is disposed radially between a respective edge of said crown portion and a said bead portion; a first carcass layer disposed radially inward of said tread and axially inward of said pair of sidewall portions, said first carcass layer extending between said pair of bead portions, said first carcass layer having a pair of first carcass layer ends, wherein on each side of the tire said first carcass layer end is positioned within a respective said bead portion at a location that is radially inward of a said bead core; and a pair of bead plies, with one located on each side of the tire in a said bead portion, each said bead ply being wrapped around a profile that is located axially outward of a said bead core, each said bead ply extending axially inward from a said profile to an intermediate position between a said bead core and a said first carcass layer end, each said bead ply then extending radially outward from said intermediate position into an inside bead ply end and an outside bead ply end with both said bead ply ends being located within a said bead portion, wherein each said inside bead ply end extends radially outward of a respective said outside bead ply end by a distance in a range of about 5 to about 8 mm, and said first carcass layer, on each side of the tire, has a length located radially inward of a said inside bead ply end that is in a range of about 30 mm to about 35 mm.

12. The tire of claim 11, further comprising a second carcass layer disposed radially inward of said tread portion and axially inward of said pair of sidewall portions, said second carcass layer extending between a pair of second carcass layer ends, one each located in a respective said bead portion at a position radially outside of said bead core.

13. The tire of claim 12, wherein said second carcass layer is disposed axially inward of said first carcass layer along each respective said bead portion.

14. The tire of claim 12, wherein each said bead ply inside end extends radially outward of a respective said second layer carcass end by a distance in a range of about 5 to about 10 mm.

15. The tire of claim 11, further comprising a pair of bead cradle strips, each said strip being located between a respective said bead core and a respective said bead ply.

16. The tire of claim 11 , wherein each said inside bead ply end extends radially outward of a said second layer carcass end by a distance in a range of about 5 mm to about 10 mm.

17. The tire of claim 11, wherein each said outside bead ply end extends radially outward and past the outermost edge of a respective said bead core.

18. A method of building a tire, comprising the steps of: applying a carcass material to a drum surface, the carcass material having a pair of sides; placing a tire intermediate on each side of the carcass material, each tire intermediate comprising a fill portion wrapped in a bead ply, the bead ply having an inside end and an outside end, wherein the inside extends past the outside end; presenting a bead core over each side of the carcass material and adjacent the intermediate at a position between the fill portion and the inside and outside ends of the bead ply; and wrapping each bead core at least partially within the tire intermediate.

19. A method of building a tire as in claim 19, further comprising the step of positioning a bead cradle strip against the manufacturing intermediate on each side of the carcass material before said step of presenting a bead core.

20. A tire constructed according to the method of claim 18.