Pneumatic tire

Patent metadata

Field	Value
Publication number	US-11618283-B2
Application number	US-201916514297-A
Country	US
Kind code	B2
Filing date	Jul 17, 2019
Priority date	Jul 23, 2018
Publication date	Apr 4, 2023
Grant date	Apr 4, 2023

Abstract

In a tire 2, a length from a center in an axial direction of a boundary between a core 30 and an apex 32 of each bead 10 to an outer end PA of the apex 32 is not less than 10 mm and not greater than 15 mm. In a state where the tire 2 is mounted on a normal rim and an internal pressure of the tire 2 is adjusted to a normal internal pressure, a shape of a main body portion 36, of a carcass ply 34, which is located in a zone from a boundary portion between a tread 4 and each sidewall 6 to the outer end PA of each apex 32 is represented by a single circular arc, and a diameter of the circular arc is not less than 75% and not greater than 90% of a cross-sectional height of a carcass 14.

First claim

What is clamed is:

1. A pneumatic tire comprising:
a tread;
a pair of sidewalls each connected to a respective axial end of the tread;
a pair of clinches each located radially inward of a respective one of the pair of sidewalls;
a pair of beads each located axially inward of a respective one of the pair of clinches, each bead having a core extending in a circumferential direction and an apex located radially outward of the core and tapering radially outward to an outermost point;
a carcass extending from one of the pair of beads to the other at an inner side of the tread and the pair of sidewalls
a belt layered over the carcass at the radially inner side of the tread and
a pair of rubber reinforcing layers each located between the carcass and a respective one of the pair of clinches, wherein
the carcass includes at least one carcass ply, a carcass ply located radially innermost among the at least one carcass ply at a tire equatorial plane having a main body portion that extends on and between one of the cores and the other and a pair of turned-up portions that are connected to the main body portion and turned up around the cores from an inner side toward an outer side in an axial direction,
in each bead a length from a center in the axial direction of a boundary between the core and the apex to the radially outermost point of the apex is not less than 10 mm and not greater than 15 mm, and
in a state where the tire is mounted on a normal rim and an internal pressure of the tire is adjusted to a normal internal pressure, on each side of the tire an inner surface cross-sectional shape of the main body portion passing through points CV, CW, and CA from outside to inside in the radial direction is formed by a single circular arc, and a diameter of the circular arc is not less than 75% and not greater than 90% of a cross-sectional height of the carcass,
the point CV being the point of intersection of the inner surface and a reference line that passes through the respective end of the belt and extends in the radial direction, the point CW being the point of intersection of the inner surface and a reference line that passes through the respective tire maximum width position and extends in the axial direction, the point CA being the point of intersection of the inner surface and a reference line that passes through the radially outermost point of the respective apex and extends in the radial direction, and the single circular arc not passing through an inner surface of the apex extending from the radially outermost point to the boundary between the core and the apex.

2. The pneumatic tire according to claim 1 , wherein
in a state where the tire is mounted on the normal rim and the internal pressure of the tire is adjusted to 10% of the normal internal pressure,
in each bead the main body portion extends along the inner surface of the apex at an inclination relative to the axial direction, and an angle of the main body portion relative to the axial direction is not less than 45° and not greater than 50°, the angle being measured between an axial line passing through the center in the axial direction of the boundary between the core and the apex and a straight line passing through both the radially outermost point of the apex and the position on the inner surface of the apex having a radial height equal to half the radial height of the apex from the center in the axial direction of the boundary between the core and the apex to the radially outermost point of the apex.

3. The pneumatic tire according to claim 1 , wherein a distance in a radial direction from a bead base line to an outermost end of each rubber reinforcing layer is not less than 35% and not greater than 45% of a cross-sectional height of the tire.

4. The pneumatic tire according to claim 1 , wherein a maximum thickness of each rubber reinforcing layer is not less than 2 mm and not greater than 4 mm.

5. The pneumatic tire according to claim 4 , wherein each of the rubber reinforcing layers has the maximum thickness along a line normal to an outer surface of the rubber reinforcing layer and passing through the radially outermost point of the respective apex.

6. The pneumatic tire according to claim 1 , wherein each apex is formed from a crosslinked rubber and the complex elastic modulus E*a of each apex is not less than 70 MPa and not greater than 130 MPa, and the loss tangent LTa of each apex is not greater than 0.18.

7. The pneumatic tire according to claim 1 , wherein each clinch is formed from a crosslinked rubber and the complex elastic modulus E*c of each clinch is not less than 7 MPa and not greater than 13 MPa, and the loss tangent LTc of each clinch is not greater than 0.08.

8. The pneumatic tire according to claim 1 , wherein a distance in a radial direction from a bead base line to an outermost end of each turned-up portion is not less than 20 mm and not greater than 30 mm.

9. The pneumatic tire according to claim 1 , wherein the carcass ply includes a plurality of carcass cords aligned with each other, and a fineness of each carcass cord is not less than 1500 dtex and not greater than 1700 dtex.

10. The pneumatic tire according to claim 1 , wherein each clinch is formed from a crosslinked rubber and the complex elastic modulus E*r of each rubber reinforcing layer is higher than the complex elastic modulus E*c of each clinch.

11. The pneumatic tire according to claim 10 , wherein the complex elastic modulus E*r of each rubber reinforcing layer is equal to the complex elastic modulus E*a of each apex, or lower than the complex elastic modulus E*a of each apex.

12. The pneumatic tire according to claim 1 , wherein each clinch is formed from a crosslinked rubber and the loss tangent LTc of each clinch is lower than the loss tangent LTr of each rubber reinforcing layer.

13. The pneumatic tire according to claim 12 , wherein the loss tangent LTr of each rubber reinforcing layer is equal to the loss tangent LTa of each apex, or lower than the loss tangent LTa of each apex.

14. The pneumatic tire according to claim 1 , wherein each apex is formed from a crosslinked rubber and the complex elastic modulus E*r of each rubber reinforcing layer is equal to the complex elastic modulus E*a of each apex, or lower than the complex elastic modulus E*a of each apex.

15. The pneumatic tire according to claim 1 , wherein each apex is formed from a crosslinked rubber and the loss tangent LTr of each rubber reinforcing layer is equal to the loss tangent LTa of each apex, or lower than the loss tangent LTa of each apex.

Assignees

• Sumitomo Rubber Ind

Inventors

• Sueno Junya
• HAYAMA Kohei

Classifications

• Y02T10/86

  Optimisation of rolling resistance, e.g. weight reduction · CPC title

• B60C2015/061

  Dimensions of the bead filler in terms of numerical values or ratio in proportion to section height · CPC title

• B60C9/0292 Primary

  Carcass ply curvature (sidewall curvature B60C13/003) · CPC title

• B60C2015/0621

  adjacent to the carcass turnup portion · CPC title

• B60C9/02 Primary

  Carcasses · CPC title