Pneumatic tire

Patent metadata

Field	Value
Publication number	US-11548326-B2
Application number	US-201917044858-A
Country	US
Kind code	B2
Filing date	Apr 3, 2019
Priority date	Apr 4, 2018
Publication date	Jan 10, 2023
Grant date	Jan 10, 2023

Abstract

A pneumatic tire is mounted on a 5° rim. A bead core includes a bottom inclined 0°-5° in a direction in which the bottom diverges outward in the radial direction as the bottom extends from an inner side toward an outer side in the width direction. A bead includes a base, a toe, a heel, and a back surface. The heel connects to the back surface by an arc. The base includes a region between a core lower inner end position on an inner circumferential surface of the bead and being identical to a position of a bead core inner end and a core lower outer end position on an inner circumferential surface of the bead and being identical to a position of a bead core outer end in the width direction. The base has a curved line projecting toward the inner side in the radial direction in a cross-section.

First claim

The invention claimed is:

1. A pneumatic tire, comprising:
a pair of bead portions disposed on both sides of a tire equatorial plane in a tire width direction; and
a bead core provided on each of the pair of bead portions,
the pneumatic tire being mounted on a 5°-taper specified rim,
the bead core has a hexagon shape in a tire meridian cross-section and includes a bead core bottom corresponding to an inner circumferential surface of the bead core and inclined within a range of 0° or larger and 5° or smaller with respect to a tire rotation axis in a direction in which the bead core bottom diverges outward in a tire radial direction as the bead core extends from an inner side in a tire width direction toward an outer side in the tire width direction,
the bead portion comprising a bead base portion formed on an inner circumferential surface of the bead portion, a toe portion located on an inner side of the bead base portion in the tire width direction, a heel portion located on an outer side of the bead base portion in the tire width direction, and a back surface portion located on an outer side of the heel portion in the tire radial direction and facing an outer side in the tire width direction,
the heel portion being connected to the back surface portion through an arc portion formed like an arc in the tire meridian cross-section,
the bead base portion comprising a region between a core lower inner end portion position located on an inner circumferential surface and being identical to a position in the tire width direction of a tire width direction inner end portion of the bead core and a core lower outer end portion position where the position located on an inner circumferential surface and being identical to a position in the tire width direction of a tire width direction outer end portion of the bead core, and
the bead base portion having a curved line projecting toward an inner side in the tire radial direction in the tire meridian cross-section; wherein
the curved line extends continuously from the core lower inner end portion position to the core lower outer end portion position in the bead base portion; and
assuming that, for the bead base portion, DP is a diameter at a core bottom outer end portion position where the position in the tire width direction is identical to the position in the tire width direction of the tire width direction outer end portion of the bead core bottom, DQ is a diameter at the core lower outer end portion position, DPR is a diameter at a position on the specified rim corresponding to the core bottom outer end portion lower position, and DQR is a diameter at a position on the specified rim corresponding to the core lower outer end portion position, (DPR−DP)/DPR×100 is at least 0.2% larger than (DQR−DQ)/DQR×100.

2. The pneumatic tire according to claim 1 , wherein the toe portion includes a straight line in the tire meridian cross-section and projects toward the inner side of the bead base portion in the tire radial direction.

3. The pneumatic tire according to claim 1 , wherein in the bead base portion, a position in the tire width direction of an outermost projection portion separated farthest from a straight line connecting the core lower inner end portion position and the core lower outer end portion position in the tire meridian cross-section is located between a position in the tire width direction of a center of the bead core bottom in the tire width direction and a position in the tire width direction of a tire width direction outer end portion of the bead core bottom.

4. The pneumatic tire according to claim 1 , wherein the bead portion includes, within a range between a position of the heel portion connected to the back surface portion and the core lower outer end portion position, a portion in which a relationship between a diameter Dn of the inner circumferential surface of the bead portion and a diameter DnR of the specified rim, both being in an identical position in the tire width direction, is represented to be 0% by a calculation (DnR−Dn)/DnR×100.

5. The pneumatic tire according to claim 1 , wherein in a case where the pneumatic tire is mounted on the specified rim, a compression ratio of rubber located on an inner side of the bead core in the tire radial direction is within a range of 45% or more and 55% or less at a position on an inner side, in the tire radial direction, of the center of the bead core bottom in the tire meridian cross-section.

6. The pneumatic tire according to claim 1 , wherein a connection portion corresponding to a portion where the arc portion and the back surface portion are connected is located within a range in the tire radial direction between a position in the tire radial direction corresponding to a maximum width portion of the bead core in the meridian cross-section and the position of the bead core bottom in the tire radial direction.

7. The pneumatic tire according to claim 1 , wherein
the toe portion projects toward the inner side of the bead base portion in the tire radial direction,
the bead base portion and the toe portion are connected through a toe side bent portion bent toward the outer side in the tire radial direction, and
a position of the toe side bent portion in the tire width direction is located on an inner side of the core lower inner end portion position in the tire width direction.

8. The pneumatic tire according to claim 1 , wherein assuming that BW is a distance between a tire inner surface and a tire outer surface on a straight line parallel to a straight line extending through a center of the bead core in the tire meridian cross-section and connecting the core lower inner end portion position and the core lower outer end portion position, the bead core has a maximum width CW in the tire meridian cross-section in a range of (BW×0.54)≤CW≤(BW×0.58).

9. The pneumatic tire according to claim 8 , wherein the bead width BW is within a range of (0.265x+20.5) mm≤BW≤(0.265x+26.5) mm with respect to a specified load x kN.

10. The pneumatic tire according to claim 1 , wherein the bead core preferably has a relationship between a maximum width CW in the tire meridian cross-section and a height CH in the tire radial direction, the relationship being within a range of 1.0≤(CW/CH)<1.5.

11. The pneumatic tire according to claim 1 , further comprising a reinforcing layer disposed extending through the inner side of the bead core in the tire radial direction of the bead core and between the inner side and the outer side of the bead core in the tire width direction of the bead core, wherein the reinforcing layer includes a cord member covered with a rubber member, and
the bead portion has a distance of 2.0 mm or more and 3.5 mm or less in the tire radial direction from a center of the bead core bottom in a tire meridian cross section to a surface of the cord member of a portion of the bead core of the reinforcing layer located on an inner side in the tire radial direction.

Assignees

• Yokohama Rubber Co Ltd

Inventors

• Tauchi Risa

Classifications

• B60C2015/0646

  at the axially inner side of the carcass main portion not wrapped around the bead core · CPC title

• B60C15/024 Primary

  Bead contour, e.g. lips, grooves, or ribs · CPC title

• B60C15/04 Primary

  Bead cores · CPC title

• B60C15/00

  Tyre beads, e.g. ply turn-up or overlap · CPC title

• B60C15/0635

  using chippers between the carcass layer and chafer rubber wrapped around the bead · CPC title