Pneumatic Tire Conductive Rubber Segmentation
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Solution Overview
Problem
Pneumatic tires with high silica content for reduced rolling resistance suffer from increased radio noise and uneven wear due to conductive rubber wear, which also compromises crack resistance and rolling performance.
Innovation Solution
A tire design featuring a non-conductive rubber cap part with a conductive rubber path that connects to the lateral end surface while avoiding exposure, allowing for adjustable rigidity and reduced noise by segmenting the conductive rubber's presence, thereby minimizing wear and enhancing crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive rubber is arranged to cover the grounding surface in the vicinity of the grounding end, then a conductive path for discharging static electricity is achieved, but the conductive rubber wears more easily and causes uneven wear such as shoulder wear
Solution Approach 1:
The tread rubber is divided into a cap part (grounding surface) and a base part, with the conductive rubber specifically positioned in the base part rather than covering the entire grounding surface. This segmentation allows the conductive function to be separated from the wear-prone surface area, reducing uneven wear while maintaining static electricity discharge capability.
Solution Approach 2:
The conductive rubber is placed only in specific regions (the base part beneath the cap part) rather than uniformly across the entire tread surface. This local quality approach concentrates the conductive function where needed while preserving the wear resistance of the cap part grounding surface.
2Reliability
If the volume of conductive rubber is increased to ensure adequate conductive path coverage, then static electricity discharge performance is improved, but rolling resistance is deteriorated
Solution Approach 1:
Instead of covering the entire grounding surface with conductive rubber (excessive action), the invention uses conductive rubber only in the base part beneath the cap part (partial action). This partial coverage is sufficient to establish the conductive path while minimizing the volume of conductive rubber needed, thereby reducing rolling resistance.
3Reliability
If conductive rubber is used to form the conductive path, then static electricity discharge is achieved, but crack resistance is deteriorated due to inferior crack resistance of conductive rubber
Solution Approach 1:
The tread rubber is segmented into a cap part made of wear-resistant rubber for the grounding surface and a base part containing the conductive rubber. This segmentation isolates the conductive rubber from direct surface exposure, protecting it from environmental degradation and mechanical stress that would otherwise reduce crack resistance.
Solution Approach 2:
The cap part acts as an intermediary protective layer between the conductive rubber in the base part and the external environment. This intermediary structure shields the conductive rubber from direct contact with road surfaces and environmental factors, preserving its crack resistance while still enabling static electricity discharge through the conductive path.
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 reduces rolling resistance, noise, and uneven wear while maintaining conductive performance, improving crack resistance and uniformity by strategically placing conductive rubber to avoid exposure and enhance lateral direction uniformity.
Implementation Method 1
a conductive part which is provided in at least one lateral end part of a pair of lateral end parts in both ends of the cap part in a tire width direction, and is formed so as to connect the grounding surface and a lateral end surface or a bottom surface of the cap part
Data Source
AI summary
An objective of the present invention is to provide a pneumatic tire whereby primarily rolling resistance is minimized and noise is minimized. This pneumatic tire tread rubber (5) comprises: a cap part (50) which is formed of non-conductive rubber and configures a grounding surface; a base part (51) which is disposed on the inner side of the cap part (50) in a tire radial direction (RD); and conductive parts (52) which are disposed in both of a pair of lateral end parts which are at ends of the cap (50) in a tire width direction, traverse the inner part of the cap (50) while avoiding a location which covers the grounding surface, and form shapes which connect the grounding surface with the bottom surface (50b) of the cap part (50) in the tire meridian cross-section. The conductive parts (52) are provided with extended sites (52b) which branch off outward to the tire width direction (WD) from conductive paths (52a) which connect the grounding surface with the bottom surface (50b) of the cap part (50). The conductive parts (52) are formed of a conductive rubber which has different rubber hardness from the non-conductive rubber which forms the cap part (50).