Run-flat tire with an improved bead to rim interface

• US 5,968,294 A
• Filed: 06/24/1998
• Issued: 10/19/1999
• Est. Priority Date: 06/10/1997
• Status: Expired due to Term

• Current Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Willard, Walter Lee Jr., Craddock, Jeffrey Scott, Endicott, James Milo
• Primary Examiner(s): Johnstone, Adrienne C.
• Application Number:
  US09/103,693
• Time in Patent Office: 482 Days
• Field of Search: 152/517, 152/539, 152/540, 152/541, 152/543, 152/544, 152/547, 152/550, 152/552, 152/555, 152/165, 152/166, 152/516, 152/155, 152/520, 152/554, 301/38.1, 301/39.1, 301/40.3
• US Class Current: 152/517
• CPC Class Codes: B60C 15/0018 not folded around the bead core, e.g. floating or down ply
• CPC Class Codes: B60C 15/0072 with ply reverse folding, i.e. carcass layer folded around the bead core from the outside to the inside
• CPC Class Codes: B60C 15/024 Bead contour, e.g. lips, grooves, or ribs
• CPC Class Codes: B60C 15/04 Bead cores
• CPC Class Codes: B60C 15/06 Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
• CPC Class Codes: B60C 15/0607 comprising several parts, e.g. made of different rubbers
• CPC Class Codes: B60C 17/00 Tyres characterised by means enabling restricted operation in damaged or deflated condition; Accessories therefor
• CPC Class Codes: Y10T 152/10819 Characterized by the structure of the bead portion of the tire
• CPC Class Codes: Y10T 152/10828 Chafer or sealing strips
• CPC Class Codes: Y10T 152/10846 Bead characterized by the chemical composition and or physical properties of elastomers or the like

Abstract

The run-flat tire has a tread for contacting a ground surface and a belt package with belt plies interior to the tread for support of the tread. A plurality of radially reinforced carcass layers are positioned interior to the belt plies and include at least one carcass layer that extends between spaced apart annular beads. The tire has a pair of sidewalls each extending radially inward from shoulders at lateral edges of the belt package to the annular beads. The sidewalls have a plurality of sidewall stiffening members to support the tire during a loss of inflation pressure. The carcass layers are disposed with the sidewall stiffening members to help support the run-flat tire with a loss of inflation pressure. The spaced apart beads have a unique design including bead cores placed at a predetermined diameter with respect to a rim diameter, dual bead fillers above the bead cores, a heel corner spaced at a radial gap distance from a rim flange and rim interface components having a seat interface distance below the bead core for mounting the run-flat tire on a conventional rim and for sustaining the run-flat tire on the conventional rim with a loss of inflation pressure within the run-flat tire.

Claims

1. A radial pneumatic tire for mounting on a conventional rim for the tire which sustains vehicle loads by contacting a ground surface at a contact patch of said tire when inflated to its conventional inflation pressure and with a loss of inflation pressure, said tire comprising:

a pair of sidewall portions including radially reinforced carcass layers disposed about sidewall stiffening members for supporting a conventional maximum tire loading from said vehicle loads with the loss of inflation pressure;

a pair of spaced apart annular beads, including elastomeric interface component portions for mounting and sustaining said tire on said conventional rim, said beads being interconnected by said carcass layers;

said elastomeric interface component portions of said beads each include a toe portion, a rim seat portion, and a heel flange portion, wherein said elastomeric interface component portions have predetermined hardness values for interfacing with said conventional rim;

said heel flange portion of said elastomeric interface component portions having a heel corner which, when said tire is mounted on said conventional rim, is radially spaced from a rim flange of said rim, over substantially all of a circumferential extent of said heel flange portion by a radial gap distance having a value in the range of about 3 millimeters to about 8 millimeters when said tire has 100 percent of said conventional inflation pressure and said conventional maximum tire loading from said vehicle loads and a radial gap distance having a zero value when said tire has a reduced inflation pressure of less than about 15 percent of said conventional inflation pressure and said conventional maximum tire loading from said vehicle loads.

2. The tire of claim 1 wherein each one of said annular beads has a bead core and a bead filler, said bead core having an annular coil of wire filaments forming a polygonal shaped cross-section with a predetermined tensile strength, said bead core having a flat innermost surface defined by an imaginary plane contacting said filaments, said flat innermost surface forming an internal bead diameter of said bead core when said annular beads are spaced apart an axial distance equal to a mounted width of said conventional rim on which said tire is to be mounted, said bead core internal diameter being about 5 millimeters larger than a rim diameter of said conventional rim.

3. The tire of claim 2 wherein said bead filler has a first bead filler extending from said bead core radially outward to form an outer stiffening member of said sidewall stiffening members and a second bead filler bounded by said first bead filler and said bead core for providing a filler material adjacent the bead core with a lower hardness than that of the first bead filler.

4. The tire of claim 3 wherein said first bead filler has a Shore A hardness value in a range of about 70 to about 90 and said second bead filler has a Shore A harness value in a range of about 20 to about 40.

5. The tire of claim 2 wherein a seat interface radial distance, measured between the flat innermost surface of said bead core and the innermost surface of said rim seat portion at a lateral centerline of said bead core after said tire is cured and before mounting on said convention rim, is in a range of about 4 millimeters to about 6 millimeters.

6. The tire of claim 5 wherein said rim seat portion of said elastomeric interface component portions has a radial thickness along said lateral centerline of said bead core which comprises more than 70 percent of the seat interface radial distance.

7. The tire of claim 6 wherein said elastomeric interface component portions have a Shore A hardness value in the range of about 50 to about 80 and a modulus of elasticity in tension at ten percent unit strain in the range of about 5 to about 9 MegaPascals (MPa).

8. The tire of claim 2 wherein a first carcass layer of said radially reinforced carcass layers is partially wrapped around said bead core in each bead forming a turn-up extending radially outward adjacent to said bead filler to an end point radially outward of said rim flange when said tire is mounted on said rim.

9. The tire of claim 8 wherein a radial distance of said turn-up from said innermost surface of said bead core to said end point has a value in a range of about 15 millimeters to about 35 millimeters.

10. The tire of claim 2 wherein said tensile strength of said bead core is defined by a tensile strength at one percent unit strain with a value in a range of about 1100 Newtons per square millimeter to about 3000 Newtons per square millimeter.

11. The tire of claim 1 including an inflated section height of said tire defined when said tire is mounted on said conventional rim and fully inflated at said conventional inflation pressure and a zero pressure section height, defined at a circumferential center of said contact patch when said tire is mounted on said conventional rim, has a zero inflation pressure and is loaded with said conventional maximum tire loading, wherein a height ratio of said inflated section height to said zero pressure section height has a value in the range of about 20 percent to about 35 percent.

12. The tire of claim 1 wherein said elastomeric interface component portions form a single component having a Shore A hardness value in the range of about 50 to about 80 and a modulus of elasticity in tension at ten percent unit strain in a range of about 5 to about 9 MegaPascals (MPa).

13. The tire of claim 1 including a heel corner angle, defined as the angle between a line tangent to said sidewall portion and said heel flange portion of said elastomeric interface component portions at said heel corner, having a value of at least 30 degrees when said tire is cured.