Pneumatic Tire Chafer Layer Support Rubber Distortion
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Solution Overview
Problem
Pneumatic tires face issues with distortion concentration at the rolled-up end of the chafer layer, leading to reduced durability and increased rolling resistance, which affects fuel efficiency and heat generation.
Innovation Solution
Incorporating a pair of support rubbers with higher modulus values than the side wall rubber, positioned to hold the rolled-up end of the chafer layer from both sides in the tire width direction, along with silica in the tread rubber and optionally a Resorcin-containing formaldehyde condensate in the rear pad rubber, to suppress distortion and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chafer layer is rolled up around the bead part, then the tire structure is formed, but distortion concentrates at the rolled-up end reducing durability
Solution Approach 1:
A support rubber is introduced as an intermediary component between the chafer layer and the bead filler. The support rubber is arranged to contact both the rolled-up end of the chafer layer and the outer surface of the bead filler, acting as a mediator that distributes and suppresses distortion concentration at the rolled-up end, thereby improving durability without compromising tire structure formation
2Productivity
If traditional rubber composition is used, then manufacturing is simple, but rolling resistance is high and fuel efficiency decreases
Solution Approach 1:
The rubber composition parameters are changed by incorporating silica as a reinforcing filler and using specific rubber materials (natural rubber, styrene-butadiene rubber, butadiene rubber) in defined proportions. These compositional parameter changes reduce the loss factor and rolling resistance while maintaining necessary mechanical properties, thereby improving fuel efficiency
3Loss of energy
If silica is added to tread rubber, then rolling resistance decreases, but heat generation increases
Solution Approach 1:
Different rubber compositions with appropriate silica contents are assigned to different regions of the tire. The tread rubber contains silica for low rolling resistance, while the support rubber and side wall rubber use compositions optimized for their specific functions. This localized quality differentiation allows the tread to achieve low rolling resistance while other parts manage heat generation through suitable material selection
4Reliability
If support rubber is added to hold chafer layer, then distortion is suppressed, but device complexity increases
Solution Approach 1:
The support rubber is merged with existing tire components, specifically being arranged to contact both the rolled-up end of the chafer layer and the outer surface of the bead filler. This merging approach allows the support rubber to perform multiple functions (holding chafer layer, distributing distortion, structural support) simultaneously, adding minimal complexity while achieving the durability improvement
Data Source
AI summary
A pneumatic tire includes: a bead core; a bead filler; a carcass ply; a side wall rubber that is arranged on the tire-outer-surface-side of the carcass ply and constitutes a tire outer surface; a chafer layer that is turned from the tire-inner-surface-side to the tire-outer-surface-side around the bead core and the bead filler and rolled up on an outer surface of the carcass ply; a pair of a tape rubber and a rear pad rubber 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; and a tread rubber, in which modulus values of the pair of the tape rubber and the rear pad rubber are higher than a modulus value of the side wall rubber, and the tread rubber contains silica.