Tire Bead Geometry Optimizing Cornering Stiffness and Rolling Resistance
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Solution Overview
Problem
Tires face a challenge in reducing rolling resistance while maintaining satisfactory cornering stiffness, as existing designs often result in significant hysteresis losses due to the stiffening effect of fillers, which requires bulky and rigid fillers, leading to increased rolling resistance.
Innovation Solution
A tire design featuring a special bead geometry with annular reinforcing structures, a specific arrangement of carcass reinforcements, and a combination of rubber compounds with varying elastic and viscous moduli, along with metal reinforcing elements, to optimize rolling resistance and cornering stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bulky and rigid filler is used to achieve cornering stiffness, then cornering stiffness is improved, but rolling resistance increases due to significant hysteresis losses
Solution Approach 1:
The patent applies local quality by using a non-uniform filler distribution with varying thickness across different radial positions. The filler thickness is optimized locally: thinner near the bead core to reduce hysteresis losses, and strategically thicker in specific regions to maintain cornering stiffness. This localized optimization resolves the contradiction between energy efficiency and handling performance.
Solution Approach 2:
The patent changes the geometric parameters of the filler, specifically its thickness profile and radial extension distance. By modifying these parameters - using a filler that extends radially outward to a distance between 5-20% of the bead radius rather than uniformly thick filler - the design achieves lower hysteresis losses while preserving the necessary structural stiffness for cornering.
2Stability of the object's composition
If stiff filler is used to guide the crown, then crown guidance is improved, but rolling resistance increases due to bulky geometry requirements
Solution Approach 1:
The filler is designed with locally optimized thickness rather than uniform bulk. The thickness varies radially, being thinner in regions where stiffness is already provided by the carcass reinforcement and thicker only where additional crown guidance is needed. This localized approach maintains stability while reducing overall material volume and hysteresis losses.
Solution Approach 2:
The patent uses composite construction combining the filler with the carcass reinforcement and bead wire structure. The filler works synergistically with these other reinforcing elements, allowing thinner filler sections to achieve the same crown guidance effect that would require much thicker standalone filler, thereby reducing hysteresis losses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tire achieves low rolling resistance while maintaining good cornering stiffness, with the described configuration reducing hysteresis losses and improving handling, especially under heavy loads.
Implementation Method 1
the carcass reinforcement being anchored in the two beads by being wrapped around the annular reinforcing structure
Implementation Method 2
The downside of this geometry is significant hysteresis losses, notably in the filler
Implementation Method 3
a filler made of at least one second rubber compound having an elastic modulus greater than or equal to 40 and less than or equal to 60 MPa
Implementation Method 4
a stiffening reinforcement formed of a plurality of metal reinforcing elements embedded in at least one third rubber compound
Data Source
AI summary
Tire comprising two beads comprising a bead wire and a carcass anchored around the two bead wires by turning back, a squat filler of small height, a sidewall stiffening reinforcement which is metallic, an outer strip of soft rubber compound, placed axially on the outside of the carcass and of the filler, and a protective layer of rubber compound, wherein the assembly formed by the stiffening reinforcement and the outer strip has a thickness EB(R) and the protective layer has a thickness EE(R), R being the distance with respect to the radially innermost point of the bead wire, and wherein the thicknesses EB(R) and EE(R) satisfy a set of geometric conditions.