Heavy Load Tire Bead Reinforcement Reduces Shear Strain
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heavy load pneumatic radial tires experience shear strain and potential separation failures at the bead heel portion due to restricted flow deformation and increased movement under load, leading to slipping and airtightness issues.
Innovation Solution
A heavy load pneumatic radial tire design featuring a carcass folded back at the bead core with a wire chafer and a reinforcing rubber layer between the carcass and wire chafer, having a lower elastic modulus than the coating rubber, arranged in a specific range of rotational angles to reduce shear strain and prevent separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sufficient tightening margins are secured to the bead base portion to prevent slipping, then airtightness is improved, but shear strain increases at the bead heel portion causing separation failure
Solution Approach 1:
The patent applies local quality by providing reinforcing cords only at the bead heel portion where separation failure occurs, rather than uniformly throughout the entire bead portion. This localized reinforcement specifically addresses the high shear strain area while maintaining overall airtightness through the general tightening margin structure.
Solution Approach 2:
The patent uses composite materials by combining rubber chafer, wire chafer, and reinforcing cords into a multi-layered structure at the bead heel portion. This composite construction distributes and reduces shear strain across different material layers, preventing separation while maintaining the necessary tightening margins for airtightness.
2Reliability
If tightening margins are increased to prevent rim slipping, then airtightness is maintained, but rubber flow deformation increases causing separation at the boundary surface
Solution Approach 1:
The patent applies preliminary action by pre-installing reinforcing cords at the bead heel portion before the tire is mounted and subjected to load. This advance reinforcement is positioned to counteract the shear strain that will occur during operation, preventing separation failure before it can happen.
Solution Approach 2:
The reinforcing cords act as an intermediary element between the rubber chafer and wire chafer at the bead heel portion. This intermediate reinforcement layer absorbs and distributes the shear strain generated by increased tightening margins, preventing direct separation at the boundary surface while maintaining airtightness.
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 design effectively prevents slipping and separation failures by securing sufficient tightening margins and reducing shear strain between the rubber chafer and wire chafer, enhancing the tire's durability and airtightness.
Implementation Method 1
A reinforcing rubber layer having a lower elastic modulus than at least one of coating rubber forming the carcass and coating rubber forming the wire chafer is arranged between the carcass and the wire chafer
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A tire 10 includes a carcass 14, and a wire chafer 22 disposed on an outer circumference of the carcass 14. A reinforcement rubber layer 24 having a lower elastic modulus than that of a coating rubber included in the carcass 14 and/or that of a coating rubber included in the wire chafer 22, is arranged between the carcass 14 and the wire chafer 22. In an area where the reinforcement rubber layer 24 is arranged, the rotational angle θ around a bead core 12c to outward in the tire width direction falls within at least a portion of the range of -45° to 90° with reference to a straight line which extends inward in the tire radial direction from the center 12c of the bead core 12, which is orthogonal to the tire width direction, and which intersects with the wire chafer