Flat-Tread Pneumatic Tire for Ice Braking and Low Rolling Resistance
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Solution Overview
Problem
Pneumatic tires for icy and snowy roads face challenges in improving braking performance on ice while minimizing rolling resistance, as existing designs often compromise on one aspect due to the high tan δ of undertread rubber layers.
Innovation Solution
A pneumatic tire design featuring a flat tread profile with increased ground contact width, reduced bead filler height, and a turned-up carcass layer, which enhances braking performance by increasing the ground contact area and reducing vertical spring constant, thereby lowering rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the undertread rubber layer is increased in thickness to improve steering stability, then steering stability is improved, but rolling resistance is degraded
Solution Approach 1:
The patent changes the physical parameters of the undertread rubber layer by reducing its thickness and modifying its rubber composition (using specific silica-containing compositions with controlled tan δ values). This allows the layer to provide sufficient steering stability while minimizing energy loss and rolling resistance.
Solution Approach 2:
The patent employs composite rubber compositions in the undertread layer, specifically using silica-filled rubber compounds with controlled viscoelastic properties. This composite material approach enables the undertread layer to maintain structural integrity and steering stability with reduced thickness, thereby lowering rolling resistance.
2Reliability
If the ground contact area is increased to improve braking performance on ice, then braking performance is improved, but rolling resistance increases
Solution Approach 1:
The patent modifies the tread profile geometry parameters to create a flat tread design with optimized ground contact characteristics. This geometric parameter change increases the effective ground contact area for braking while controlling the overall contact patch to minimize rolling resistance.
Solution Approach 2:
The patent applies different local qualities to different regions of the tread, with the flat tread profile providing optimized local contact characteristics for braking performance while maintaining overall tire efficiency. The undertread rubber composition is also locally optimized to reduce energy loss in the contact region.
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 improves braking performance on ice and reduces rolling resistance by increasing the ground contact area and energy loss reduction, while maintaining necessary traction indices for snowy conditions.
Implementation Method 1
a vertical spring constant of the tire is reduced, and the side wall portion is likely to be deflected. Thus, an energy loss in the tread portion can be relatively reduced
Implementation Method 2
a ground contact area of the tread portion can be increased, and braking performance on ice can be improved
Data Source
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AI summary
Provided is a pneumatic tire capable of improving braking performance on ice and reducing rolling resistance. In the pneumatic tire including a tread portion (1), a pair of side wall portions (2), and a pair of bead portions (3), a carcass layer (4) is mounted between the bead portions (3), the tread portion (1) has a multilayer structure including a cap tread rubber layer (11A) and an undertread rubber layer (11B), and a snow traction index STI is 180 or more. A tread radius (TR) in a meridian cross-section of the tread portion (1) falls within a range of from 80% to 140% of a tire outer diameter (OD), a ground contact width (TCW) of the tread portion (1) falls within a range of from 66% to 83% of a tire cross-sectional width (SW), and a height (BFH) of a bead filler (6) is 40% or less of a tire cross-sectional height (SH).