Pneumatic Tire Carcass Thread for Static Discharge Under Deformation
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Solution Overview
Problem
Existing pneumatic tires with conductive fibers break due to repeated deformation, leading to ineffective static electricity discharge and compromised ride quality, especially when encountering large deformations like curbs.
Innovation Solution
A pneumatic tire design featuring a conductive thread with an electrical resistance of 10⁸ Ω/cm or less and a stress of 13 N or less at 1% elongation, integrated into the carcass ply, which extends from the bead to the tread portion, to prevent breakage and maintain low electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If composite fibers containing conductive fibers are arranged on the surface of the carcass to reduce electrical resistance, then static electricity discharge is improved, but the conductive fibers break due to repeated deformation and large local deformation
Solution Approach 1:
The patent changes the key parameter of the conductive thread from high stress-at-elongation (conventional) to low stress-at-elongation (13 N or less at 1% elongation). This parameter change makes the conductive thread more flexible and less prone to breakage during tire deformation, while still maintaining electrical conductivity to discharge static electricity.
Solution Approach 2:
The conductive thread is constructed as a composite material combining conductive fibers (for electrical conductivity) with non-conductive fibers (for flexibility and structural support). This composite structure allows the thread to maintain both electrical function and mechanical flexibility, preventing breakage during tire operation and large deformations.
2Reliability
If composite fibers with high modulus are used to reduce electrical resistance, then conductivity is improved, but sidewall deflection is inhibited and ride quality deteriorates
Solution Approach 1:
The patent changes the stress-at-1%-elongation parameter to 13 N or less, which corresponds to lower modulus materials. This allows the sidewall to deflect naturally during riding, improving ride quality, while the conductive thread still provides sufficient electrical conductivity for static electricity discharge.
Solution Approach 2:
By using a composite structure of conductive and non-conductive fibers in the conductive thread, the patent achieves a balance between electrical conductivity and mechanical flexibility. The non-conductive fibers contribute to the low modulus and flexibility needed for good ride quality, while the conductive fibers maintain the electrical conductivity function.
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 suppresses conductive thread breakage, maintains low electrical resistance, and ensures excellent ride comfort even under large local deformations, while effectively discharging static electricity.
Implementation Method 1
the conductive thread has an electrical resistance of 10⁸ Ω/cm or less
Data Source
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AI summary
To provide a pneumatic tire with low electrical resistance and excellent ride comfort, even after the tire is subjected to a large local deformation, by suppressing breakage of a conductive thread. A pneumatic tire has a carcass 6. The carcass 6 includes a carcass ply 6A extending from one bead portion 4 to the other bead portion 4 through a tread portion 2. The carcass ply 6A is provided with at least one conductive thread 9 extending from one bead portion 4 to at least the tread portion 2. The conductive thread 9 has an electrical resistance of 108 Ω/cm or less per unit length. The conductive thread 9 has a stress of 13 N or less at 1% elongation.