Pneumatic Tire Tread Thickness Distribution for Wear and Fuel Economy
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Solution Overview
Problem
Pneumatic tires with narrow width and large bead diameter face challenges in reducing rolling resistance and improving fuel economy while maintaining even wear resistance, particularly at the shoulder portion during cornering.
Innovation Solution
The tire design includes a carcass extending between bead cores and tread portions, with specific relationships between tire section width, bead diameter, and tread thickness distribution to optimize energy loss reduction and air resistance, while preventing uneven shoulder wear through a defined tread thickness distribution curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tire section width is reduced to decrease tread volume and energy loss, then fuel economy is improved, but the shoulder portion is subjected to high ground contact pressure and long ground contact length causing uneven shoulder wear
Solution Approach 1:
The tread thickness is made non-uniform in the axial direction, with specific thickness distribution defined by the function f(y) where the rate of change increases to y=0.4 and decreases thereafter. This creates local variations in tread thickness to optimize both energy loss and wear resistance in different regions of the tread.
Solution Approach 2:
The invention changes the parameter of tread thickness distribution along the axial direction by defining specific constraints on the function f(y). The parameters include: f(0.4) in range 0.03-0.06, and the rate of change pattern, which optimizes the balance between reducing energy loss and preventing shoulder wear.
2Loss of energy
If the tread rubber volume is reduced to improve fuel economy, then rolling resistance is reduced, but grip performance and abrasion resistance are deteriorated
Solution Approach 1:
Different regions of the tread are given different thicknesses to perform different functions. The tread thickness distribution optimized by f(y) ensures adequate thickness in regions critical for grip and wear resistance while minimizing thickness in regions where energy loss is the primary concern.
Solution Approach 2:
The invention optimizes the tread thickness parameter distribution along the axial direction by defining specific constraints on f(y). This parameter optimization allows reduction of overall tread volume for lower rolling resistance while maintaining sufficient thickness in critical areas for grip and abrasion resistance.
Data Source
AI summary
A pneumatic tire includes a carcass extending between bead cores of bead portions through a tread portion. A tire section width Wt (unit: mm) in relation to a bead diameter Db (unit: inch) satisfies the following equations, Wt≤−0.7257×(Db)2+42.763×Db−339.67, and Wt≥−0.7257×(Db)2+48.568×Db−552.33. In a tread thickness distribution curve f(y) represented by equation f(y)=1−t(y)/t(0), when y=0.4, the value of f(y) is of from 0.03 to 0.06, and a rate of change of the value of f(y) increases to y=0.4 and decreases thereafter, where t(y) denotes a tread thickness at each tire axial position Py, and y represents a ratio of an axial distance from the tire equatorial plane, to the maximum-width L of the carcass.