Pneumatic Tire Conductive Under Tread for Static Discharge
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Solution Overview
Problem
Pneumatic tires with silica-blended sidewalls experience high volume resistivity, leading to blocked electric conduction between the rim and under tread, resulting in static electricity accumulation on vehicles, causing radio noise and discomfort.
Innovation Solution
A pneumatic tire design featuring a non-conductive tread with a conductive under tread and penetration portion, conductive clinches and beads, and a conductive reinforcing layer on the carcass, ensuring effective electric discharge through the clinches, carcass, under tread, and penetration portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silica is blended in sidewalls to reduce rolling resistance, then fuel consumption performance is improved, but volume resistivity increases and electric conduction is blocked
Solution Approach 1:
The sidewall is divided into two distinct layers: an outer sidewall layer containing silica for low rolling resistance, and an inner sidewall layer containing carbon black for electrical conductivity. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the sidewall are assigned different material compositions based on their functional requirements. The outer region uses silica-blended rubber for energy efficiency, while the inner region uses carbon black-blended rubber for electrical discharge, creating local quality variations that resolve the contradiction.
2Use of energy by moving object
If silica is blended in tread to reduce rolling resistance, then fuel consumption performance is improved, but conductivity decreases and static electricity accumulates
Solution Approach 1:
The tread structure is segmented into an outer tread layer with silica for low rolling resistance and an inner under-tread layer with carbon black for conductivity. This segmentation enables the tread to simultaneously achieve fuel efficiency and static electricity discharge.
Solution Approach 2:
The under-tread layer acts as an intermediary conductive pathway between the tread and the rim. It mediates the contradiction by providing electrical conductivity without affecting the silica-blended outer tread's rolling resistance properties.
3Reliability
If carbon black is used in sidewalls and tread, then conductivity is improved, but rolling resistance increases
Solution Approach 1:
Carbon black is locally concentrated in specific layers (inner sidewall layer and under-tread layer) where conductivity is required, while being minimized or excluded from the outer tread and outer sidewall layers where low rolling resistance is critical. This localized quality distribution resolves the contradiction.
Solution Approach 2:
The tire structure is segmented into conductive zones (inner layers) and non-conductive zones (outer layers), with carbon black strategically placed only in the conductive zones. This segmentation allows the tire to achieve both conductivity and low rolling resistance.
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 tire effectively discharges static electricity, suppressing radio noise and sparks, while maintaining low rolling resistance for improved fuel efficiency.
Implementation Method 1
a conductive under tread located inward of the tread in a radial direction... a conductive penetration portion penetrating through the tread, exposed at an end thereof on the tread surface, and extending at another end thereof to the under tread... a pair of conductive clinches extending from ends of the sidewalls... a conductive reinforcing layer laminated on the carcass
Data Source
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AI summary
[Object] To provide a pneumatic tire 2 from which static electricity is easily discharged. [Solution] The tire 2 includes penetration portions 8, an under tread 6, a belt 18, a carcass 16, and clinches 12. The carcass 16 includes a large number of cords aligned with each other, and a conductive topping rubber. The electric resistance Rc of the carcass which is represented by the following mathematical formula is less than 1.0 × 10 8 ©. Rc = Á / g / 2 × 3.14 × r × L × 10 In the mathematical formula, p is the volume resistivity (©·cm) of the topping rubber of the carcass, g is the minimum thickness (mm) of the topping rubber, r is the distance (m) from the axis of the tire to an outer end, in the radial direction, of the clinch, and L is the length (m) of the carcass from an end of the reinforcing layer to the outer end, in the radial direction, of the clinch.