Tire Crown Reinforcement with Circumferential Elements
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Solution Overview
Problem
Current heavy-duty tires face endurance issues due to shear stresses and increased operating temperatures, leading to cracks and reduced cornering stiffness, especially when loaded and driven at high speeds on twisty roads.
Innovation Solution
A tire design with a radial carcass reinforcement featuring a crown reinforcement formed of crossed layers with specific rubber compounds and circumferential reinforcing elements, including a skim layer with a polymer compound that enhances dynamic properties and maintains endurance, cornering stiffness, and rolling resistance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tire uses conventional crown reinforcement layers without circumferential reinforcing elements, then the manufacturing complexity is lower, but the cornering stiffness and dynamic properties deteriorate under heavy loads and high speeds
Solution Approach 1:
The patent applies composite materials by combining circumferential reinforcing elements (metallic or non-metallic cords) with the rubber compound layers to create a crown reinforcement structure that provides both structural integrity and enhanced dynamic properties including cornering stiffness under heavy loads and high speeds
Solution Approach 2:
The circumferential reinforcing elements are specifically positioned in the crown reinforcement layers at locations where cornering stiffness is needed, providing localized reinforcement without unnecessarily increasing overall structural complexity throughout the entire tire
2Productivity
If the tire operates at high speeds over long journeys, then the distance travelled increases and wear is reduced, but the endurance of the crown reinforcement deteriorates due to shear stresses and temperature rise
Solution Approach 1:
The crown reinforcement is divided into multiple working layers with circumferential reinforcing elements distributed across them, allowing shear stresses to be distributed across multiple interfaces rather than concentrated in a single layer, thereby improving endurance under high-speed operation
Solution Approach 2:
The patent incorporates circumferential reinforcing elements and rubber compound layers with specific properties (elastic modulus >9 MPa, tan(δ)max <0.100) that beforehand cushion and resist the thermal and mechanical stresses that will develop during high-speed operation, preventing crack formation and maintaining reliability
3Loss of energy
If the skim layer uses rubber compound with lower elastic modulus to reduce rolling resistance, then fuel efficiency improves, but the cornering stiffness and dynamic properties deteriorate
Solution Approach 1:
The patent optimizes the elastic modulus parameter of the skim layer rubber compound to a specific range (>9 MPa) that balances rolling resistance and cornering stiffness, while also controlling tan(δ)max (<0.100) to minimize energy loss without sacrificing dynamic performance
Solution Approach 2:
The combination of circumferential reinforcing elements with the skim layer creates a composite structure that provides the necessary stiffness for cornering while the rubber compound formulation maintains acceptable rolling resistance characteristics
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 design improves cornering stiffness and maintains endurance and rolling resistance performance, even under heavy loads and high speeds, while reducing the risk of cracks and improving fuel efficiency by using specific rubber compounds and circumferential reinforcing elements.
Implementation Method 1
the elastic modulus under tension at 10% elongation of at least one skim layer of at least one working crown layer is greater than 9 MPa, the maximum value of tan(δ), denoted tan(δ)max, of the said at least one skim layer of at least one working crown layer is less than 0.100
Data Source
AI summary
Tire comprising a crown reinforcement formed of at least two working crown layers each being formed of reinforcing elements inserted between two skim layers of rubber compound, a first layer S of polymer compound being in contact with at least one working crown layer and in contact with the carcass reinforcement and the crown reinforcement comprising at least one layer of circumferential reinforcing elements. The elastic modulus under tension at 10% elongation of at least one skim layer of at least one working crown layer is greater than 9 MPa, the maximum value of tan(δ), denoted tan(δ)max, of the at least one skim layer of at least one working crown layer is less than 0.100 and the complex dynamic shear modulus G*, measured at 10% and 60° C. on the return cycle, of the first layer S of polymer compound is greater than 1.35 MPa.