RUN-FLAT TIRE

• US 20120145299A1
• Filed: 07/21/2010
• Published: 06/14/2012
• Est. Priority Date: 08/20/2009
• Status: Abandoned Application

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Hino, Hidehiko, Hanya, Masahiro
• Application Number:
  US13/391,209
• Publication Number:
  US 20120145299A1
• Time in Patent Office: Days
• US Class Current: 152/516
• CPC Class Codes: B60C 13/02 Arrangement of grooves or ribs
• CPC Class Codes: B60C 15/024 Bead contour, e.g. lips, grooves, or ribs
• CPC Class Codes: B60C 17/0009 comprising sidewall rubber inserts, e.g. crescent shaped inserts
• CPC Class Codes: B60C 2015/0614 characterised by features of the chafer or clinch portion, i.e. the part of the bead contacting the rim
• CPC Class Codes: B60C 5/14 with impervious liner or coating on the inner wall of the tyre
• CPC Class Codes: B60C 9/14 built-up with sheets, webs, or films of homogeneous material, e.g. synthetics, sheet metal, rubber

Abstract

Disclosed is a run-flat tire having greatly increased run-flat endurance. The disclosed run-flat tire is provided with: a carcass (6) extending from a tread section (2) through a sidewall portion (3) to a bead core (5) of a bead portion (4); and a side-reinforcement rubber layer (9) that has a crescent-shaped cross-section and is disposed inside the carcass (6) in the sidewall portion (3). A heat-conducting rubber (11) having a coefficient of thermal conductivity of not less than 0.3 W/(m·K) is disposed on the inner cavity surface (12) of the tire. At least part of said heat-conducting rubber (11) is disposed in a side-reinforcement rubber layer projection area (T) where the side-reinforcement rubber layer (9) is projected onto the inner cavity surface (12) of the tire.

Claims

1. A run-flat tire provided with a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion and a side-reinforcement rubber layer having a crescent-shaped cross-section and being disposed inside the carcass in said sidewall portion;

characterized in that

a heat-conducting rubber having a coefficient of thermal conductivity of not less than 0.3 W/(m·

K) is disposed on the inner cavity surface of the tire, and

at least part of said heat-conducting rubber is disposed in a side-reinforcement rubber layer projection area where the side-reinforcement rubber layer is projected onto the inner cavity surface of the tire.

2. The run-flat tire as set forth in claim 1, characterized in that said heat-conducting rubber extends from said side-reinforcement rubber layer projection area to at least a bead bottom surface of said bead portion.

3. The run-flat tire as set forth in claim 2, characterized in that said heat-conducting rubber extends through said bead bottom surface to an axially outside surface of said bead portion.

4. The run-flat tire as set forth in any one of claims 1 to 3, characterized in that said heat-conducting rubber is disposed on a whole extent of the inner cavity surface of the tire.

5. The run-flat tire as set forth in any one of claims 1 to 3, characterized in that

a radially inner end or a radially outer end of said heat-conducting rubber terminates within the side-reinforcement rubber layer projection area, and

a radial length H4 of the heat-conducting rubber within the side-reinforcement rubber layer projection area T is not less than 30% of a radial length H3 of the side-reinforcement rubber layer projection area T.

6. The run-flat tire as set forth in claim 1, characterized in that the maximal thickness of said heat-conducting rubber is in a range of from 0.3 to 3.0 mm.

7. The run-flat tire as set forth in claim 1, characterized in that said heat-conducting rubber comprises

base material rubber comprising diene rubber, and

coal pitch-based carbon fiber.

8. The run-flat tire as set forth in claim 7, characterized in that

said heat-conducting rubber comprises from 20 to 80% by mass of natural rubber and/or isoprene rubber based on 100% by mass of said diene rubber.

9. The run-flat tire as set forth in claim 7 or 8, characterized in that

said heat-conducting rubber comprises from 1 to 50 parts by mass of coal pitch-based carbon fiber based on 100 parts by mass of said base material rubber.

10. The run-flat tire as set forth in claim 7, characterized in that said coal pitch-based carbon fiber has an average diameter of from 1 to 80 μ

m and an average length of from 0.1 to 15 mm

11. The run-flat tire as set forth in claim 1, characterized in that at least one of outer surfaces of said sidewall portion 3 has a plurality of dimples having a diameter D2 of from 2 to 70 mm and a depth (e) of from 0.1 to 4.0 mm.