Multi-Core Cable Insulation for Low-Temperature Bending
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Solution Overview
Problem
Existing multi-core cables face issues with bending resistance at both low temperatures and room temperature, as the insulating material can wear or crack due to interfacial friction, leading to conductor exposure and loss of electrical conductivity.
Innovation Solution
A core wire for multi-core cables is developed with a conductor made by twisting elemental wires and an insulating layer containing polyethylene-based resin, with specific linear expansion coefficients and elastic moduli to enhance bending resistance across a wide temperature range, and a melting point that ensures mechanical properties are maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulating material is used in multi-core cables, then the cable can be manufactured with standard materials, but the insulating layer wears or cracks due to interfacial friction during bending, leading to conductor exposure and loss of electrical conductivity
Solution Approach 1:
The patent applies parameter changes by carefully controlling the melting point of the polyethylene-based resin within 80°C to 130°C and adjusting the product of linear expansion coefficient and elastic modulus (C1×E1) to be between 0.01 MPaK−1 and 0.90 MPaK−1. These parameter optimizations reduce hardening at low temperatures and minimize interfacial friction during bending, preventing wear and cracking of the insulating layer while maintaining reliability.
Solution Approach 2:
The patent uses polyethylene-based resin as the main component of the insulating layer, which can be considered a composite material solution. This resin provides a balance of mechanical properties, flexibility at low temperatures, and resistance to interfacial friction, thereby improving both wear resistance and bending resistance simultaneously.
2Strength
If the insulating layer is made harder to improve wear resistance, then the material strength increases, but the bending resistance decreases due to increased hardening and interfacial friction at low temperatures
Solution Approach 1:
The patent resolves this contradiction by optimizing the product of linear expansion coefficient and elastic modulus (C1×E1) to be between 0.01 MPaK−1 and 0.90 MPaK−1. This parameter control ensures that the insulating layer maintains adequate strength for wear resistance while preventing excessive hardening at low temperatures, thereby preserving bending resistance and overall reliability.
Solution Approach 2:
The patent utilizes the phase transition characteristics of polyethylene-based resin with a melting point between 80°C and 130°C. By selecting resin within this melting point range, the material maintains appropriate flexibility and mechanical properties across the operating temperature range, preventing both excessive hardening and wear during bending operations.
3Stability of the object's composition
If the insulating layer shrinks at low temperatures to maintain dimensional stability, then the structural integrity is preserved, but the conductor is repeatedly compressed and may break, losing electrical conductivity
Solution Approach 1:
The patent addresses this contradiction by controlling the linear expansion coefficient and elastic modulus product (C1×E1) within the range of 0.01 MPaK−1 to 0.90 MPaK−1. This parameter optimization reduces the magnitude of shrinkage at low temperatures while maintaining dimensional stability, preventing repeated compression of the conductor and preserving electrical conductivity.
Solution Approach 2:
The patent applies thermal expansion principles by selecting polyethylene-based resin with specific thermal properties (melting point 80°C to 130°C and controlled C1×E1 product). This selection minimizes thermal shrinkage effects at low temperatures, preventing conductor compression and maintaining both dimensional stability and electrical conductivity.
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 provides improved bending resistance and wear resistance in a temperature range from low temperatures to room temperature, preventing conductor exposure and maintaining electrical conductivity through reduced hardening and increased mechanical properties.
Implementation Method 1
the melting point of the polyethylene-based resin is 80° C. or higher and 130° C. or lower
Implementation Method 2
an elastic modulus E1 at −35° C., namely (C1×E1) is 0.01 MPaK−1 or more and 0.90 MPaK−1 or less
Implementation Method 3
the product of a linear expansion coefficient C1 of the insulating layer in the range of 25° C. to −35° C. and an elastic modulus E1 at −35° C.
Data Source
AI summary
A core wire for multi-core cables includes a conductor obtained by twisting a plurality of elemental wires, and an insulating layer coated on an outer peripheral surface of the conductor. The insulating layer contains polyethylene-based resin as a main component, and the product of a linear expansion coefficient C1 of the insulating layer in the range of 25° C. to −35° C. and an elastic modulus E1 at −35° C., namely (C1×E1), is 0.01 MPaK−1 or more and 0.90 MPaK−1 or less. The melting point of the polyethylene-based resin is 80° C. or higher and 130° C. or lower.