Aluminum Wire Harness Fusing for Low Resistance
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Solution Overview
Problem
Aluminum wire cables in automotive wiring face challenges due to the formation of insulating oxide layers and deformation over time, leading to increased electrical resistance and connector failure, as conventional crimped connections do not provide a robust, low-resistance connection that withstands environmental exposure.
Innovation Solution
A method involving crimping an electrical wire cable with uninsulated strands, followed by fusing the protruding strands using thermal processes like welding or soldering to eliminate voids and bond them to the terminal, reducing inter-strand resistance and preventing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional crimped connections are used for aluminum wire cables, then the connection process is simple and fast, but the electrical resistance increases over time due to oxide layer formation and strand deformation
Solution Approach 1:
The wire strands are pre-tinned with solder before crimping, which creates a protective coating that prevents oxide layer formation during storage and installation. This preliminary protective action ensures that when the crimping occurs, the strands are already protected against the harmful oxidation that would otherwise increase resistance over time.
Solution Approach 2:
The connection combines multiple materials and methods: aluminum wire strands, solder coating, and copper terminal. The solder acts as an intermediary material that bonds well to both aluminum and copper, creating a composite connection structure that overcomes the poor electrical contact between aluminum strands and prevents galvanic corrosion while maintaining low resistance.
2Ease of operation
If aluminum wire cables with multiple strands are used, then the cable flexibility is improved, but the individual strands do not connect well electrically due to oxide layer formation
Solution Approach 1:
The soldering process is applied locally to the strand ends that will be crimped into the terminal, rather than the entire cable. This localized treatment ensures that the critical connection points have excellent electrical contact while maintaining the flexibility of the overall cable structure with its multiple strands.
Solution Approach 2:
The natural tendency of aluminum to form oxide layers is converted into a benefit by applying solder that adheres to the aluminum strands. The solder creates a metallurgical bond that actually improves electrical contact between strands compared to bare aluminum, turning the oxidation-prone nature of aluminum into an opportunity for enhanced connection through the intermediary solder material.
3Reliability
If aluminum wire strands are crimped tightly to reduce voids, then electrical contact is improved, but stress relaxation and creep cause deformation over time
Solution Approach 1:
The crimping process parameters are optimized to apply sufficient pressure to eliminate voids and ensure good electrical contact, but not excessive pressure that would cause permanent deformation. The solder coating also changes the mechanical properties of the strand surface, providing a more compliant interface that can accommodate slight movements without creating voids or excessive stress concentration points.
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
This method achieves a low-resistance, corrosion-resistant connection by eliminating voids and bonding the wire strands, enhancing the durability and reliability of aluminum wire cable connections in automotive wiring.
Implementation Method 1
fusing the protruding strands using thermal processes like welding or soldering
Implementation Method 2
fusing the protruding strands using thermal processes like welding or soldering
Implementation Method 3
bonding the wire strands, enhancing the durability and reliability of aluminum wire cable connections
Data Source
AI summary
A wiring harness assembly is presented. The wiring harness assembly is formed by a method that includes the steps of crimping an electrical wire cable within a crimping feature of an electrical terminal having wire strands protruding from the crimping feature and fusing the wire strands of protruding portion, or “wire brush” so that the wire strands are in intimate contact, thereby eliminating voids between individual wire strands of the wire brush. The wires may be fused by laser welding, soldering, or brazing. The method may be especially beneficial for wire strands having an insulative oxide layer, such as aluminum. The bonding reduces the resistance between the wire strands due to insulating oxide layers on the surface of the wire strands and inhibiting of corrosion by eliminating inter-strand gaps where electrolytes in solution may enter and cause galvanic corrosion.