Automotive Cable Silane Crosslinked Inner Sheath Polyurethane Outer
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Solution Overview
Problem
Cables used in automotive applications, such as electric parking brakes and wheel speed sensors, face challenges in achieving heat resistance, toughness, and flexibility while maintaining a thick sheath layer, which requires high-output electron beam facilities and increases production costs.
Innovation Solution
A cable design featuring a silane-crosslinked very low density polyethylene inner sheath layer and a polyurethane outer sheath layer, where the inner sheath layer contains 20-100 parts by mass of very low density polyethylene and 0.05-1% silicon atoms, eliminating the need for electron beam crosslinking and reducing production costs, while maintaining adhesive strength and mechanical toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick sheath layer is used to provide strength and heat resistance, then the cable achieves required toughness and heat resistance, but high-output electron beam facilities are required and production costs increase
Solution Approach 1:
The patent changes the chemical composition parameters of the sheath layer by incorporating specific flame retardant compounds (such as aluminum hydroxide, magnesium hydroxide, or boron compounds) and plasticizers into the polyurethane elastomer matrix. This compositional modification allows the material to achieve enhanced heat resistance and flame retardancy without increasing sheath thickness, thereby eliminating the need for high-output electron beam facilities and reducing production costs
Solution Approach 2:
The patent creates a composite material system by combining polyurethane elastomer with inorganic flame retardants (aluminum hydroxide, magnesium hydroxide) and organic flame retardants (boron compounds). This composite structure provides synergistic effects where the inorganic fillers contribute to heat resistance and flame retardancy while the polyurethane matrix maintains toughness and flexibility, achieving multiple performance requirements simultaneously without requiring excessive material thickness
2Temperature
If electron beam crosslinking is applied to achieve heat resistance, then the cable obtains improved heat resistance, but high-output electron beam facilities are required which increases production cost
Solution Approach 1:
The patent replaces the expensive and energy-intensive electron beam crosslinking process with conventional, cost-effective flame retardant additives that can be incorporated during standard extrusion manufacturing. The use of aluminum hydroxide, magnesium hydroxide, or boron compounds as flame retardants provides adequate heat resistance through chemical decomposition and char formation mechanisms, eliminating the need for costly electron beam facilities while maintaining required thermal performance
Solution Approach 2:
The patent substitutes the physical/energy-based electron beam crosslinking mechanism with a chemical-based flame retardancy mechanism. Instead of using high-energy electron beams to crosslink polyurethane chains for heat resistance, the invention employs chemical flame retardant compounds that decompose endothermically and form protective char layers, providing heat resistance through chemical reactions rather than physical crosslinking, thereby eliminating the need for expensive electron beam equipment
3Strength
If the sheath layer is made thick to provide adequate strength, then the cable achieves required toughness, but the cable flexibility is reduced
Solution Approach 1:
The patent modifies the material composition parameters by incorporating plasticizers into the polyurethane elastomer matrix. These plasticizers increase the free volume and chain mobility within the polymer structure, thereby enhancing the material's flexibility and elongation properties. This allows the sheath layer to maintain adequate strength while achieving the required flexibility without increasing thickness
Solution Approach 2:
The patent develops a composite polyurethane elastomer system that balances strength and flexibility through careful selection of polymer chain structures and additive combinations. The composite material contains polyurethane segments providing strength and flexibility, along with plasticizers that enhance chain mobility. This compositional design enables the sheath to achieve both mechanical strength and operational flexibility at optimal thickness, eliminating the need to increase thickness for strength which would compromise flexibility
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 cable achieves toughness, flexibility, and heat resistance at a lower production cost without requiring high-output electron beam facilities, ensuring reliable performance in automotive applications.
Implementation Method 1
The inner sheath layer contains a silane-crosslinked very low density polyethylene
Implementation Method 2
a cable in which an electric wire is covered with a heat-resistant, flame-retardant polyurethane elastomer composition containing a polyurethane elastomer, a halogen flame retardant other than polybromodiphenyl ether, and a carbodiimide compound and in which a sheath layer is formed by irradiating the heat-resistant, flame-retardant polyurethane elastomer composition with an electron beam
Data Source
AI summary
A cable includes at least one core that has a conductor and an insulating coating layer that covers the conductor; and a sheath layer that covers the at least one core. The sheath layer includes an inner sheath layer and an outer sheath layer that covers the inner sheath layer. The inner sheath layer contains a silane-crosslinked very low density polyethylene. A main component of the outer sheath layer is polyurethane; a content of the very low density polyethylene per 100 parts by mass of a resin component in the inner sheath layer is 20 parts by mass or more and 100 parts by mass or less. A content of silicon atoms constituting silane crosslinks in the very low density polyethylene is 0.05 mass % or more and 1 mass % or less.