Dual Sheath Cable for Electromechanical Brakes
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Solution Overview
Problem
Conventional cables for electromechanical parking brakes and wheel speed sensors face a trade-off between strength and flexibility due to the need for a thicker sheath layer for heat resistance, which compromises their overall performance.
Innovation Solution
A cable design featuring a dual sheath layer structure with a crosslinked very low density polyethylene inner sheath layer and a polyurethane outer sheath layer, where the inner sheath layer has a specific elastic modulus and silicon atom content for enhanced heat resistance and flexibility, eliminating the need for electron beam crosslinking and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the sheath layer is increased to improve strength, then the strength of the sheath layer is improved, but the flexibility of the cable decreases
Solution Approach 1:
The sheath layer is divided into two distinct layers: an inner sheath layer made of crosslinked very low density polyethylene and an outer sheath layer made of polyurethane. The inner layer provides strength and heat resistance, while the outer layer provides flexibility and durability, thus resolving the contradiction between strength and flexibility through functional segmentation.
Solution Approach 2:
The patent uses composite materials by combining very low density polyethylene and polyurethane in a layered structure. The inner layer uses crosslinked VLDPE for high strength and heat resistance, while the outer layer uses polyurethane for flexibility and wear resistance, achieving both strength and flexibility simultaneously through material composition.
2Temperature
If electron beam irradiation is used to improve heat resistance through crosslinking, then the heat resistance is improved, but the manufacturing cost increases
Solution Approach 1:
The patent changes the chemical parameters of the polyethylene by incorporating specific additives (silane compounds, peroxides, or carboxylic acid anhydrides) that enable crosslinking through conventional heating rather than electron beam irradiation. This parameter change in the material composition allows thermal crosslinking at lower costs while achieving the required heat resistance.
Solution Approach 2:
The patent replaces the expensive electron beam irradiation process with cheaper chemical crosslinking methods using readily available additives. The use of inexpensive crosslinking agents (silane compounds, peroxides, or anhydrides) that can be mixed into the polymer before extrusion eliminates the need for costly electron beam equipment and processing.
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 a balance of strength, flexibility, and heat resistance, making it suitable for electromechanical applications while minimizing manufacturing costs.
Implementation Method 1
the inner sheath layer contains a very low density polyethylene that is subject to crosslinking
Implementation Method 2
irradiating the heat-resistant polyurethane elastomer composition with an electron beam
Implementation Method 3
the electron beam irradiation improves the heat resistance by crosslinking the polyurethane in the sheath layer
Data Source
AI summary
The cable according to one embodiment of the invention comprises: one or a plurality of core members, each having a conductor and an insulation cover material covering the conductor; and a sheath layer covering the one or the plurality of core members. The sheath layer comprises an inner sheath layer, and an outer sheath layer covering the inner sheath layer. The inner sheath layer comprises a crosslinked very low density polyethylene. The main component of the outer sheath layer is polyurethane. Relative to 100 parts by mass of resin component in the inner sheath layer, the very low density polyethylene content is between 20 parts by mass and 100 parts by mass inclusive. The elastic modulus of the inner sheath layer at 25° C. is between 5 MPa and 30 MPa inclusive.