Pneumatic Tire Carcass Composition for Low Noise and Steering Stability
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Solution Overview
Problem
Existing pneumatic tires face a trade-off between reduced road noise and improved steering stability, as softening the cap tread rubber for noise reduction compromises steering stability.
Innovation Solution
Specifying the thickness of the carcass ply, composition of the carcass coating rubber, and the ratio of cap tread rubber hardness to carcass coating rubber storage modulus, using natural rubber, styrene-butadiene copolymer rubber, and carbon black with a specific nitrogen adsorption surface area, to achieve a balanced hardness ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cap tread rubber is softened to reduce road noise, then the road noise is reduced, but the steering stability is compromised
Solution Approach 1:
The invention divides the tire structure into distinct functional layers: the cap tread rubber layer (for noise reduction) and the undertread/carcass ply layer (for steering stability). By segmenting the tire into these independent functional zones with specific thickness ratios, the patent allows the cap tread to be softened for noise reduction while the underlying carcass structure maintains steering stability through its optimized thickness of 0.50-2.00 mm and specific rubber composition.
Solution Approach 2:
The patent applies local quality by giving different rubber compositions and properties to different layers. The cap tread rubber has specific hardness characteristics for noise reduction, while the undertread and carcass coating rubber have different compositions (including natural rubber and styrene-butadiene copolymer rubber in specific ratios) to provide the necessary structural support and steering stability. Each layer is locally optimized for its specific function.
2Object-affected harmful factors
If the cap tread rubber is softened to reduce road noise, then the road noise is reduced, but the tire rigidity is lowered
Solution Approach 1:
The tire is segmented into a soft cap tread layer for noise reduction and a rigid undertread/carcass structure for maintaining overall tire rigidity. The carcass ply thickness of 0.50-2.00 mm and its specific rubber composition create a rigid foundational structure that compensates for the softened cap tread, ensuring the tire maintains sufficient rigidity for proper vehicle support and handling.
Solution Approach 2:
The patent uses composite materials by combining different rubber types in the carcass coating rubber (natural rubber and styrene-butadiene copolymer rubber in specific ratios) and using different rubber formulations in the cap tread versus the undertread. This composite approach allows the tire to exhibit both the noise-absorbing properties of softer rubber in the cap and the rigidity of the reinforced carcass structure.
Data Source
AI summary
To achieve reduced road noise and improved steering stability, an embodiment of the present invention provides a pneumatic tire in which a carcass ply has a thickness of from 0.50 mm to 2.00 mm, a carcass coating rubber contains: natural rubber and a styrene-butadiene copolymer rubber as diene rubbers; and carbon black having N2SA of from 35 to 140 m2/g, a hardness (Hs cap) of a cap tread rubber and a storage modulus (E'carcass) of the carcass coating rubber satisfy 5 ≤ (Hs cap)/(E'carcass) ≤ 15.