Pneumatic Tire Inner Conductive Path for Static Charge Suppression
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Solution Overview
Problem
Existing tires with conductive members to suppress static electricity face issues of increased electrical resistance due to fiber breakage during vehicle travel, leading to reduced electrostatic suppression performance.
Innovation Solution
A tire design incorporating a linear conductive portion with a volume resistivity of less than 1×10⁸ Ω·cm, extending from the bead portion to the belt layer, disposed on the tire inner surface, and optimized in length and overlap ratios to maintain electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive fiber is disposed along the surface of a carcass ply to reduce electrical resistance, then electrostatic suppression performance is improved, but the conductive fiber breaks due to repeated rubbing during tire deformation, causing electrical resistance to increase
Solution Approach 1:
A protective rubber layer is introduced as an intermediary between the conductive fiber and the external environment. This rubber layer shields the conductive fiber from direct contact and rubbing during tire deformation, preventing fiber breakage while maintaining the conductive path for electrostatic suppression.
Solution Approach 2:
The conductive fiber is embedded within the rubber structure during manufacturing, providing beforehand protection against mechanical stress. The rubber matrix acts as a cushioning medium that absorbs deformation stresses before they can directly damage the conductive fiber, ensuring long-term durability.
2Loss of energy
If silica content in tread rubber is increased to suppress rolling resistance, then fuel efficiency is improved, but electrical resistance increases due to high insulating characteristics of silica, decreasing electrostatic suppression performance
Solution Approach 1:
The tire structure is segmented into distinct functional zones: the tread rubber contains silica for low rolling resistance, while separate conductive components (carbon black reinforced rubber or conductive fibers) are positioned in the inner liner and bead areas. This segmentation allows each zone to optimize its specific function without compromising the other.
Solution Approach 2:
The tire employs composite material construction with silica-filled rubber in the tread for fuel efficiency and carbon black-filled rubber or conductive fiber composites in the inner liner for electrostatic suppression. These composite materials enable simultaneous achievement of low rolling resistance and low electrical resistance in different tire regions.
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 effectively maintains tire electrical resistance after travel, ensuring consistent electrostatic suppression performance by preventing conductive fiber breakage and maintaining a conductive path.
Implementation Method 1
a linear conductive portion extending continuously at least from one of the bead portions to the belt layer... having a volume resistivity of less than 1×10⁸ Ω·cm
Data Source
AI summary
A pneumatic tire includes: a pair of bead portions; at least one carcass layer extending between the pair of bead portions; a belt layer disposed on an outer side of the carcass layer in a tire radial direction; and a tire inner surface rubber layer constituting a tire inner surface. The tire further includes a linear conductive portion extending continuously at least from one of the bead portions to the belt layer and disposed on the tire inner surface rubber layer. The linear conductive portion is at least partially exposed to a tire inner cavity side and has a volume resistivity of less than 1×10{circumflex over ( )}8 Ω·cm.