Pneumatic Tire Chafer Layer Support Rubber Design
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Solution Overview
Problem
Pneumatic tires with chafer layers in the bead part experience distortion concentration and separation issues at the rolled-up end, which are not effectively addressed by existing designs where the pad rubber is positioned outside the chafer layer.
Innovation Solution
Incorporating a pair of support rubbers with a higher modulus than the side wall rubber, positioned between the side wall rubber and the carcass ply, to hold the rolled-up end of the chafer layer, along with a tape rubber to reduce level differences and prevent excessive distortion and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pad rubber is arranged on the outside in the tire radial direction further than the chafer layer, then the structure is simplified and manufacturing is easier, but the concentration of distortion at the rolled-up end of the chafer layer is not effectively suppressed
Solution Approach 1:
The support structure is divided into multiple segments: the chafer layer itself, the rolled-up end portion, and the pad rubber positioned outside the chafer layer. This segmentation allows each component to perform its specific function - the chafer layer provides structural support while the pad rubber specifically targets distortion at the rolled-up end, resolving the contradiction between manufacturing simplicity and distortion suppression effectiveness
Solution Approach 2:
The rolled-up end portion of the chafer layer acts as an intermediary element between the main chafer layer and the pad rubber. This intermediary structure allows the pad rubber to effectively suppress distortion by providing a transition zone that distributes stresses, thereby maintaining both ease of manufacture and reliability
2Reliability
If the pad rubber is arranged to cover the rolled-up end of the chafer layer, then distortion suppression is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The pad rubber is positioned locally at the outer radial side of the chafer layer, specifically targeting the region where distortion concentrates at the rolled-up end. This localized placement provides effective distortion suppression without requiring the pad rubber to cover the entire chafer layer, thereby reducing device complexity while maintaining reliability
Solution Approach 2:
Instead of covering the entire chafer layer, the pad rubber is positioned to provide partial coverage at the critical rolled-up end region. This partial action is sufficient to suppress distortion concentration while avoiding the excessive complexity that would result from full coverage, resolving the contradiction between reliability and device complexity
Data Source
AI summary
A pneumatic tire includes a pair of bead cores; a pair of bead fillers that are connected to the pair of bead cores; a carcass ply that is suspended between the pair of bead cores; a side wall rubber that is arranged on a tire-outer-surface-side of the carcass ply and constitutes a tire outer surface; a chafer layer that is turned from a tire-inner-surface-side to the tire-outer-surface-side around the bead cores and the bead fillers and rolled up on an outer surface of the carcass ply; and a pair of support rubbers that are located between the side wall rubber and the carcass ply and arranged so as to hold a rolled-up end of the chafer layer from both sides in a tire width direction. A modulus values of the pair of support rubbers are higher than a modulus value of the side wall rubber.