Pneumatic tire

Patent metadata

Field	Value
Publication number	US-11040580-B2
Application number	US-201816770571-A
Country	US
Kind code	B2
Filing date	Dec 4, 2018
Priority date	Dec 6, 2017
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

In a pneumatic tire including a side reinforcing layer, the maximum width W0 of a bead core and the widths W1, W2 of the bead core at innermost and outermost sides in the radial direction, respectively, satisfy W1>W2 and W2≤0.5×W0. W0 is toward the inside of the center of the bead core in the radial direction. A carcass is folded and curved along the bead core, and a folded back portion of the carcass extends toward the sidewalls while contacting a body of the carcass. A rubber occupancy ratio in a region formed by the body and the folded back portion of the carcass is 0.1% to 15%. The cross-sectional area S2 of a filler toward the outside of the carcass in the lateral direction, the hardness H2 of the filler, the cross-sectional area S1 of a side reinforcing layer and the hardness H1 of the side reinforcing layer satisfy 0.15≤(S2×H2)/(S1×H1)≤0.60.

First claim

The invention claimed is:

1. A pneumatic tire, comprising:
a tread portion extending in a tire circumferential direction and having an annular shape;
a pair of sidewall portions disposed on opposite sides of the tread portion;
a pair of bead portions disposed toward the inside of the sidewall portions in a tire radial direction;
a bead core provided in each of the bead portions;
a carcass layer mounted between the pair of bead portions; and
a side reinforcing layer provided toward the inside of the carcass layer in the sidewall portion in a tire lateral direction and having a crescent-shape in cross-section; wherein
the bead core comprises at least one bead wire wound in the tire circumferential direction,
a plurality of circumferential portions of the bead wire form at least one row arranged in the tire lateral direction and a plurality of layers overlapping in the tire radial direction,
a maximum width W 0 of the bead core, a width W 1 of one of the layers, which is located at an innermost side in the tire radial direction, and a width W 2 of another of the layers, which is located at an outermost side in the tire radial direction, satisfy relationships W 1 >W 2 and W 2 ≤0.5×W 0 ,
the layer of the plurality of layers, having the maximum width W 0 , is located toward the inside in the tire radial direction of a center position of the bead core in the tire radial direction,
when a polygonal shape formed by common tangent lines of the plurality of circumferential portions of the bead wire in a meridian cross-section is defined as an outer shape of the bead wire, internal angles α, β of corner portions located on opposite ends of one side of the outer shape, which is located toward the inside in the tire radial direction, satisfy relationships α>90° and β>90°,
a peripheral length L 0 of the outer shape, a length L 1 of the side of the outer shape, which is located toward the inside in the tire radial direction, a length L 2 of another side of the outer shape, which is connected to the side located toward the inside in the tire radial direction and which is inclined at a bead toe, and a length L 3 of another side of the outer shape, which is connected to the side located toward the inside in the tire radial direction and which is inclined at a bead heel, satisfy relationships 0.25≤(L 1 +L 2 )/L 0 ≤0.40 and 1.0≤(L 1 +L 2 )/(2×L 3 )≤2.5,
the carcass layer comprises a body portion extending from the tread portion through each of the sidewall portions to each of the bead portions, and a folded back portion folded at each of the bead portions and curved along a periphery of the bead core, and extending toward each of the sidewall portions while contacting the body portion from an outer end position of the bead core in the tire radial direction, and
when an auxiliary line A 0 being perpendicular to the carcass layer through an intersection point between an outline of an outer surface of the sidewall portion and a straight line separated from the bead toe by 20 mm toward the outside in the tire radial direction and extending in parallel with the tire radial direction, an auxiliary line A 1 separated from the auxiliary line A 0 by 5 mm toward the inside in the tire radial direction and being parallel with the auxiliary line A 0 , and an auxiliary line A 2 separated from the auxiliary line A 0 by 5 mm toward the outside in the tire radial direction and being parallel with the auxiliary line A 0 are drawn in the meridian cross-section, a cross-sectional area SR of a portion of the side reinforcing layer, which is present between the auxiliary line A 1 and the auxiliary line A 2 , and an area SB of a closed region formed by the body portion and the folded back portion of the carcass layer satisfy a relationship 0.4≤SB/SR≤2.5.

2. The pneumatic tire according to claim 1 , wherein in the meridian cross-section, the peripheral length L 0 of the outer shape of the bead core and a tire cross-sectional width K on an auxiliary line A 0 being perpendicular to the carcass layer through an intersection point between an outline of an outer surface of the sidewall portion and a straight line separated from the bead toe by 20 mm toward the outside in the tire radial direction and extending in parallel with the tire radial direction satisfy the relationship 1.2≤L 0 /K≤5.0.

3. The pneumatic tire according to claim 1 , wherein a ratio of a total area of rubber present in a closed region formed by the body portion and the folded back portion of the carcass layer to an area of the closed region is from 0.1% to 15%.

4. The pneumatic tire according to claim 3 , wherein a filler layer is provided toward the outside of the body portion and the folded back portion of the carcass layer in the tire lateral direction.

5. The pneumatic tire according to claim 4 , wherein when an auxiliary line A 0 being perpendicular to the carcass layer through an intersection point between an outline of an outer surface of the sidewall portion and a straight line separated from the bead toe by 20 mm toward the outside in the tire radial direction and extending in parallel with the tire radial direction, an auxiliary line A 1 separated from the auxiliary line A 0 by 5 mm toward the inside in the tire radial direction and being parallel with the auxiliary line A 0 , and an auxiliary line A 2 separated from the auxiliary line A 0 by 5 mm toward the outside in the tire radial direction and being parallel with the auxiliary line A 0 are drawn in the meridian cross-section, a cross-sectional area SF of a portion of the filler layer, which is present between the auxiliary line A 1 and the auxiliary line A 2 , and an area SB of a closed region formed by the body portion and the folded back portion of the carcass layer satisfy a relationship 0.6≤SB/SF≤2.4.

6. The pneumatic tire according to claim 4 , wherein when an auxiliary line A 0 being perpendicular to the carcass layer through an intersection point between an outline of an outer surface of the sidewall portion and a straight line separated from the bead toe by 20 mm toward the outside in the tire radial direction and extending in parallel with the tire radial direction, an auxiliary line A 1 separated from the auxiliary line A 0 by 5 mm toward the inside in the tire radial direction and being parallel with the auxiliary line A 0 , and an auxiliary line A 2 separated from the auxiliary line A 0 by 5 mm toward the outside in the tire radial direction and being parallel with the auxiliary line A 0 are drawn in the meridian cross-section, a cross-sectional area SR of a portion of the side reinforcing layer, which is present between the auxiliary line A 1 and the auxiliary line A 2 , a cross-sectional area SF of a portion of the filler layer, which is present between the auxiliary line A 1 and the auxiliary line A 2 , and an area SB of a closed region formed by the body portion and the folded back portion of the carcass layer satisfy a relationship 0.3≤SB/(SR+SF)≤2.0.

7. The pneumatic tire according to claim 1 , wherein an average diameter of the bead wire is from 0.8 mm to 1.8 mm.

8. The pneumatic tire according to claim 1 , wherein a total cross-sectional area of the bead wire is from 10 mm 2 to 50 mm 2 .

9. The pneumatic tire according to claim 1 , wherein the length L 2 of the side of the outer shape of the bead core, which is connected to the side located toward the inside in the tire radial direction and which is inclined at the bead toe, is from 1.5 mm to 8 mm.

10. The pneumatic tire according to claim 1 , wherein the length L 1 of the side of the outer shape of the bead core, which is located toward the inside in the tire radial direction, is from 2 mm to 10 mm.

11. The pn

Assignees

• Yokohama Rubber Co Ltd

Inventors

• Kouda Hiraku
• Matsuda Jun
• Tanno Atsushi
• Nagayasu Masaaki
• Takemori Ryohei
• Sasaya Yuki

Classifications

• B60C15/06

  Flipper strips, fillers, or chafing strips {and reinforcing layers for the construction of the bead} · CPC title

• B60C15/04 Primary

  Bead cores · CPC title

• B60C17/0009

  comprising sidewall rubber inserts, e.g. crescent shaped inserts · CPC title

• B60C15/0054 Primary

  with ply turn-up portion parallel and adjacent to carcass main portion · CPC title

• B60C2017/0063

  Modulus; Hardness; Loss modulus or "tangens delta" · CPC title