Pneumatic Tire Conductive Structure for Static Discharge Durability
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Solution Overview
Problem
Pneumatic tires with electrically conductive portions face durability issues due to deformation and fatigue, leading to increased electrical resistance and reduced electrostatic suppression performance, especially with increasing silica content in rubber compounds.
Innovation Solution
A pneumatic tire design featuring an electrically conductive portion with a linear structure, including an electrically conductive linear member and a non-conductive member, intertwined and strategically positioned between the bead and belt layers with a separation portion to maintain conductivity and durability, and a method of manufacturing involving slitting and separating the conductive portion before vulcanization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrically conductive portion is disposed continuously from the bead portions to the belt layer, then static electricity can flow from the bead portions to the belt layer for discharge, but the electrically conductive portion may break due to fatigue caused by repeated deformation and changing tension
Solution Approach 1:
The electrically conductive portion is divided into multiple segments along its length, with separation portions created at specific locations. These separation portions allow the conductive portion to be divided into discrete sections that can deform independently, reducing stress concentration and preventing breakage while maintaining continuous electrical conductivity through the segments.
Solution Approach 2:
The separation portions are strategically positioned at specific locations where deformation and tension changes are most severe. This local modification allows the conductive portion to maintain continuity and electrical function while accommodating deformation at critical points, resolving the contradiction between maintaining strength and allowing flexibility.
2Loss of energy
If silica content in rubber compounds is increased to improve fuel economy, then fuel efficiency improves, but the resistance value of the cap tread increases and electrostatic suppression performance deteriorates
Solution Approach 1:
The electrostatic conduction path is segmented into multiple sections along the tire structure. By distributing conductive elements across different layers and positions (including the electrically conductive portion extending from bead to belt layer), the system maintains overall conductivity even when individual segments have high resistance due to silica content, thus preserving electrostatic suppression performance while allowing high silica content for fuel economy.
Solution Approach 2:
The electrically conductive portion acts as an intermediary conductive path that bridges the bead portions and the belt layer. This intermediate structure provides an alternative conduction route that compensates for the high resistance introduced by silica in the cap tread, maintaining electrostatic suppression capability while allowing the use of high-silica rubber compounds for improved fuel economy.
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 solution enhances the durability of the electrically conductive portion and maintains effective electrostatic suppression performance by reducing electrical resistance and preventing breakage due to deformation, ensuring reliable discharge of static electricity over extended travel distances.
Implementation Method 1
an electrically conductive portion extending between the pair of bead portions and having at least one separation portion, the electrically conductive portion having a linear structure, the linear structure including an electrically conductive linear member formed in a linear shape by molding an electrically conductive material with an electrical resistivity of less than 1×10^8 Ω/cm
Data Source
AI summary
Provided is a pneumatic tire including a pair of bead portions; at least one carcass layer extending between the pair of bead portions; a belt layer disposed outward of the carcass layer in a tire radial direction; a tread rubber disposed outward of the belt layer in the tire radial direction; a pair of sidewall rubbers disposed outward of the carcass layer in a tire lateral direction; and an electrically conductive portion extending between the pair of bead portions and having at least one separation portion, the electrically conductive portion having a linear structure, the linear structure including an electrically conductive linear member formed in a linear shape by molding an electrically conductive material with an electrical resistivity of less than 1×10{circumflex over ( )}8 Ω/cm.