Tire Crown Reinforcement with Unequal Axial Widths
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Solution Overview
Problem
Current heavy-duty tires face challenges in maintaining endurance and wear resistance, especially under high-speed conditions, due to shear stresses and thermal issues in the crown reinforcement, leading to cracks and reduced performance.
Innovation Solution
A tire design with a radial carcass reinforcement featuring unequal axial widths for working crown layers, a layer of rubber compound between them, and a polymer compound layer extending to the tread, along with circumferential reinforcing elements, to decouple shear stresses and enhance stiffness, while using a filled elastomeric compound with specific properties to improve cohesion and dynamic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a layer of rubber compound is placed between the ends of working crown layers to reduce shear stresses, then the endurance of the crown reinforcement is improved, but the device complexity increases due to additional layers and manufacturing steps
Solution Approach 1:
The patent combines the protective layer and the decoupling layer into a single integrated layer of rubber compound. This layer simultaneously protects the ends of the working crown layers from mechanical damage and decouples them to reduce shear stresses, thereby improving endurance without adding multiple separate components and manufacturing steps.
Solution Approach 2:
The single layer of rubber compound performs multiple functions: it acts as a protective layer shielding the reinforcement ends, and simultaneously serves as a decoupling layer that reduces shear stresses between working crown layers. This multi-functionality resolves the contradiction by achieving improved endurance without increasing structural complexity.
2Reliability
If the working crown layers are decoupled to reduce shear stresses, then the endurance is improved, but the manufacturing precision requirements increase due to positioning constraints
Solution Approach 1:
The patent uses a flexible layer of rubber compound as a decoupling element between the working crown layers. This flexible film allows for stress distribution and accommodation while maintaining the decoupling function, reducing the need for precise positioning compared to rigid decoupling structures.
Solution Approach 2:
The patent changes the physical parameters of the decoupling layer by using rubber compound with specific viscoelastic properties. This material can deform and adapt to positioning variations, thereby reducing the stringency of manufacturing precision requirements while still achieving the desired stress reduction and improved endurance.
3Strength
If circumferential reinforcing elements are added to the crown reinforcement, then the cornering stiffness is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent merges the circumferential reinforcing elements with the existing crown reinforcement structure by placing them within the same layer configuration. This integration allows the cornering stiffness to be improved without requiring separate manufacturing processes or additional assembly steps, thereby avoiding increased manufacturing complexity.
4Reliability
If a filled elastomeric compound is used to improve cohesion and dynamic properties, then the wear resistance is improved, but the manufacturing cost increases
Solution Approach 1:
The patent changes the compositional parameters of the rubber compound by incorporating specific fillers to improve cohesion and dynamic properties. This enhances wear resistance while the filled compound can be processed using standard vulcanization methods, avoiding excessive cost increases by leveraging existing manufacturing capabilities.
Data Source
AI summary
Tire comprising a crown reinforcement comprising two working crown layers having unequal axial widths. Layer C of rubber compound is placed between ends of the working crown layers. Second layer S of polymer compound is in contact with at least one working crown layer and the carcass reinforcement, which comprises a layer of circumferential reinforcing elements arranged radially between two working crown layers. Distance d between the end of the axially narrowest working layer and the working layer separated from it by layer C is 1.1ø<d<2.2ø, ø being the diameter of the reinforcing elements, in a meridian plane. Second layer S is made up of a filled elastomer blend having a macro dispersion coefficient Z≥65 and a maximum tan(δ) value less than 0.100. Its complex dynamic shear modulus G*, measured at 10% and 60° C. on the return cycle is greater than 1.35 MPa.