Tire having optimized sidewalls and crown reinforcement made up of two working crown layers and a layer of circumferential reinforcing elements

Patent metadata

Field	Value
Publication number	US-11850893-B2
Application number	US-202017616089-A
Country	US
Kind code	B2
Filing date	Jun 4, 2020
Priority date	Jun 6, 2019
Publication date	Dec 26, 2023
Grant date	Dec 26, 2023

Abstract

A tire having a radial carcass reinforcement, made up of a single layer of reinforcing elements anchored in each of the beads by being turned up around a bead wire, reinforced by a stiffener. The two working crown layers are the only ones present to form the crown reinforcement over at least 75% of the width of the tread, the absolute value of the difference between the absolute values of the angles α2 and α1 being greater than 7°, α2 being greater than α1 in terms of absolute value, the mean angle α satisfying the relationship 13+131*exp(−L/100)<α<28+110*exp(−L/100), the reinforcing elements of the carcass reinforcement being cords which, in the test referred to as the permeability test, yield a flow rate of less than 20 cm3/min, a rubber compound being present within the cords, and, in the sidewall of the tire, the profile of the outer surface of the tire is at a constant distance from the carcass reinforcement layer between the points F and A, and meets the outer surface of the bead at the point C, forming two successive circular arcs.

First claim

The invention claimed is:

1. A tire configured to be fitted on a drop-center rim of the “15° drop-center” type, comprising:
a radial carcass reinforcement made up of a single carcass reinforcement layer formed of reinforcement elements,
a crown reinforcement, comprising two working crown layers of reinforcing elements that are crossed from one layer to the other, making with the circumferential direction angles (α1, α2) greater than 8°, said angles α1 and α2 being oriented on either side of the circumferential direction, and at least one layer of circumferential reinforcing elements,
the crown reinforcement being radially capped by a tread,
said tread being connected to two beads via two sidewalls,
the carcass reinforcement layer being anchored in each of the beads by being turned up around a bead wire to form a main part of the carcass reinforcement layer extending from one bead wire to the other, and
a turn-up of the carcass reinforcement layer in each of the beads, said turn-up of the carcass reinforcement being reinforced by at least one layer of reinforcement elements or a stiffener, wherein:
said two working crown layers and said at least one layer of circumferential reinforcing elements are the only ones present to form the crown reinforcement over not less than 75% of the axial width of the crown reinforcement,
the reinforcing elements of the radially outermost working crown layer ( 52 ) form an angle (α2) with the circumferential direction that is greater in terms of absolute value than the angle (α1) formed by the reinforcing elements of the radially innermost working crown layer ( 51 ) with the circumferential direction,
the absolute value of the difference between the absolute values of the angles (α2) and (α1) is greater than 7°,
the mean angle α satisfies the relationship:
13+131*exp(− L/ 100)<α<28+110*exp(− L/ 100),

α being defined by the relationship α=Arctan((tan(|α1|)*tan(|α2|)) 1/2 ), L being the maximum width of the tire measured in the axial direction and expressed in mm,
the metal reinforcing elements of said carcass reinforcement layer are cords that, in the test referred to as the permeability test, yield a flow rate of less than 20 cm 3 /min, and
a rubber compound is present at least locally within the structure of said cords,
in each of the beads, in a meridian section of said tire:
any point of the profile of the outer surface (S) of the tire, between a first point (F), itself defined by the intersection of an axially oriented straight line, passing through the axially outermost point (E) of the main part of the carcass reinforcement layer and the outer surface (S) of the tire, and a point (A), is at a constant distance (T) from the main part of the carcass reinforcement layer, said distance being measured at any point in a direction normal to the main part of the carcass reinforcement layer,
wherein the point (A) is radially on the outside of a first circle (C 1 ) of radius (R 1 ) that is centered on the end of the turn-up of the carcass reinforcement layer, (R 1 ) being between 8 and 13 mm,
radially on the inside of the point (A), the outer surface (S) of the tire extends by an arc of a circle of radius (R 2 ), the center of which is axially on the outside of the surface (S) of the tire,
the circular arc of radius (R 2 ) is tangential at its radially innermost end (B) to a circular arc of radius (R 3 ), the center of which is axially on the inside of the surface (S) of the tire, and continues the outer surface (S) of the tire radially inwards as far as the point (C), said point (C) being a point of tangency between the circular arc of radius (R 3 ) and the circle (C 2 ) of radius (R 1 ) centered on the radially outermost end of the stiffener, and
wherein said point (C) being radially on the inside of the axially outermost point (D) of the circle (C 2 ).

2. The tire according to claim 1 , wherein the rupture potential index F2/FR2 of the radially outermost working crown layer is less than ⅙, where:
FR2 is the breaking force in uniaxial extension of each of the cords of the radially outermost working crown layer,
F2=p 2 *Tc*[(tan(|α1|)/((tan(|α1|)+tan(|α2|)))/cos 2 (|α2|)+C F ], where
Tc=0.078*P*R S *(1−(Rs 2 −R L 2 )/(2*Rt*Rs)),
P is the nominal inflation pressure of the tire according to the ETRTO,
C F =0.00035*(min((L−80)/sin(|α1|),(L−80)/sin(|α2|),480)−480),
p 2 is the pitch at which the reinforcing elements of the radially outermost working crown layer are laid, measured perpendicularly to the reinforcing elements at the circumferential median plane,
Rs=Re−Es,
Re is the external radius of the tire, measured at the radially outermost point on the tread surface of the tire, said surface being extrapolated in order to fill any voids there might be,
Es is the radial distance between the radially outermost point of the tire and the orthogonal projection thereof onto the radially exterior face of a reinforcing element of the radially innermost working crown layer,
RL is the mean of the radii of the axially outermost points on each side of the tire,
Rt is the radius of the circle passing through three points situated on the exterior surface of the tread outside of the voids, defined from a shoulder end at respective axial distances equal to ¼, ½ and ¾ of the width of the tread.

3. The tire according to claim 1 , wherein the rupture potential index F2/FR2 of the radially outermost working crown layer is less than ⅛.

4. The tire according to claim 1 , wherein the two working crown layers and said at least one layer of circumferential reinforcing elements are the only ones present to form the crown reinforcement over the entirety of the axial width of the crown reinforcement ( 5 ).

5. The tire according to claim 1 , wherein the radius (R 2 ) is between 50% and 125% of the distance between the point (F) and the center of gravity of the bead wire.

6. The tire according to claim 1 , wherein the radius (R 3 ) being between 50% and 125% of the distance between the point (F) and the center of gravity of the bead wire.

7. The tire according to claim 1 , wherein the distance (T), measured in a direction normal to the main part of the carcass reinforcement layer, is greater than 3 mm and preferably less than 7 mm.

8. The tire according to claim 1 , wherein the radial distance between the point (F) and the point (A) is greater than 70% of the radial distance between the point (F) and the radially outermost point (G) of the outer surface (S) of the tire, for which the distance, measured in a direction normal to the main part of the carcass reinforcement layer, between said main part of the carcass reinforcement layer and the surface (S), is equal to (T), said distance between any point, on the outer surface (S) of the tire, radially between the points (F) and (G) and the main part of the carcass reinforcement layer being constant.

9. The tire according to claim 1 , wherein the radially outermost end of the stiffener is radially on the outside of the end of the turn-up of the carcass reinforcement layer.

10. The tire according to claim 1 , wherein in any meridian plane, in each bead, the tire has a retention reinforcement surrounding the bead wire and a volume of rubber compound in direct contact with the bead wire.

11. The tire according to claim 1 , wherein the rupture potential index F1/FR1 of the radially innermost working crown layer is less than ⅓, where:
FR1 is the breaking force in uniaxial extension of each of the cords of the radially innermost working layer,
F 1= p 1 *Tc *[(tan(|α2|)/((tan(|α1|)+tan(|α2|)))/cos 2 (|α1|)+ C F ], where

p 1 is the pitch at which the reinforcing elements of the radially inner

Assignees

• Michelin & Cie

Inventors

• Rehab Hichem
• Noel Sébastien
• Rolland Maxime
• Dayet Patrick

Classifications

• B60C15/0628 Primary

  comprising a bead reinforcing layer · CPC title

• B60C9/0007

  Reinforcements made of metallic elements, e.g. cords, yarns, filaments or fibres made from metal · CPC title

• B60C9/04

  the reinforcing cords of each carcass ply arranged in a substantially parallel relationship · CPC title

• B60C15/024 Primary

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

• B60C2009/0269

  Physical properties or dimensions of the carcass coating rubber · CPC title