Shielded Wire Thermal Expansion Clearance Design
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Solution Overview
Problem
Shielded electric wires with multiple wires in a metal pipe have a large bending radius, leading to poor wiring properties and risk of the wire being crushed due to thermal expansion.
Innovation Solution
A shielded electric wire configuration with a single electric wire in a tubular metal pipe, where the inner diameter of the pipe is set to accommodate the expanded conductor and insulator dimensions, ensuring a sufficient clearance to prevent crushing and improve bending radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple electric wires are collectively put into a metal pipe, then shielding function is achieved and ground connection can be done once, but the diameter of the metal pipe becomes large and the bending radius becomes large, resulting in poor wiring property
Solution Approach 1:
The patent divides the single large metal pipe into multiple smaller metal pipes, with each pipe containing one electric wire. This segmentation allows each wire to have its own dedicated shielding pipe, reducing the bending radius and improving wiring properties while maintaining the shielding function through individual pipe enclosures.
2Ease of operation
If the diameter of the metal pipe is reduced to improve wiring property, then bending radius is reduced, but the electric wire expands due to thermal expansion and is crushed
Solution Approach 1:
The patent calculates the thermal expansion of the electric wire in advance using the formula a′=a+αa×a×Δt for the conductor and b′=b+αb×b×Δt for the insulator, and sets the inner diameter c of the metal pipe to satisfy c≥a′+2b′. This preliminary calculation ensures sufficient clearance is built into the pipe dimensions before the wire undergoes thermal expansion, preventing crushing while allowing for reduced pipe diameter and improved wiring properties.
3Ease of operation
If the inner diameter of the metal pipe is set small to reduce bending radius, then wiring property improves, but the clearance becomes insufficient and the wire is crushed during thermal expansion
Solution Approach 1:
The patent changes the parameter of the metal pipe's inner diameter from a fixed small value to a calculated value based on thermal expansion parameters. By using the formula c≥a+2b+αa×a×Δt+2αb×b×Δt, the inner diameter is optimized to provide just enough clearance for thermal expansion while keeping the pipe diameter as small as possible, thus improving wiring property without compromising wire protection.
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 configuration prevents the electric wire from being crushed while reducing the bending radius and enhancing wiring properties by maintaining a sufficient clearance between the expanded wire and the pipe inner diameter.
Implementation Method 1
the electric wire expands due to a temperature environment where the shielded electric wire is used
Data Source
AI summary
A shielded electric wire includes one metal pipe and one electric wire having a conductor and an insulator. An outer diameter of the conductor at 25° C. is set as a, a coefficient of linear expansion of the conductor is set as αa, and a temperature difference between a maximum temperature and 25° C. is set as Δt, an outer diameter a′ of the conductor after thermal expansion is a′=a+αa×a×Δt, and when a wall thickness of the insulator at 25° C. is set as b and a coefficient of linear expansion of the insulator is set as αb, an insulator wall thickness b′ after thermal expansion is b′=b+αb×b×Δt, and an inner diameter c of the one metal pipe is set to satisfy c≥a′+2b′.