Flexible Multi-Layered Bus Bar Weight Reduction
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Solution Overview
Problem
Conventional bus bars in electrified vehicles are heavy due to their copper composition, which affects the vehicle's weight and efficiency in power distribution, and they face issues with current sharing due to oxidation of aluminum surfaces.
Innovation Solution
A flexible bus bar assembly with multiple layers, where one layer is made of aluminum and the other of copper, with end portions of a different material to form a non-conductive oxide layer at different rates, and a soldering alloy or polymer coating to facilitate current sharing and reduce weight by allowing bending and flexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used for bus bar material, then electrical conductivity is improved, but weight increases significantly
Solution Approach 1:
The bus bar employs a composite structure with an aluminum core and copper cladding. The aluminum core provides lightweight structural support while the copper cladding ensures high electrical conductivity at the contact points. This composite material approach resolves the contradiction by combining the advantages of both materials - the low density of aluminum and the high conductivity of copper - creating a bus bar that is both lightweight and electrically efficient.
2Weight of moving object
If aluminum is used for bus bar material, then weight is reduced, but current sharing is compromised due to oxidation
Solution Approach 1:
The copper cladding layer protects the aluminum core from oxidation while maintaining electrical connectivity. The copper layer acts as a barrier to oxygen, preventing the formation of non-conductive oxide layers on the aluminum surface. This ensures that the aluminum bus bar maintains both its weight advantage and its current sharing capability through the protective copper envelope.
Solution Approach 2:
The bus bar structure applies different material properties to different regions: the core uses lightweight aluminum for structural support and weight reduction, while the surface cladding uses oxidation-resistant copper for electrical contact and current sharing. This local differentiation of material quality allows the bus bar to optimize both weight and electrical performance simultaneously.
3Ease of manufacture
If conventional single-layer bus bar is used, then manufacturing is simple, but flexibility and adaptability to various configurations are limited
Solution Approach 1:
The bus bar is divided into multiple layers - an aluminum core layer and copper cladding layers - that can be manufactured separately and then assembled. This segmentation allows each layer to be optimized independently for its specific function while maintaining manufacturing simplicity through standardized processes. The layered structure also inherently provides flexibility as the thin layers can bend and conform to various configurations more easily than a solid monolithic bus bar.
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 reduces the overall weight of the bus bar while enhancing its flexibility and current sharing capabilities, improving power distribution efficiency and accommodating various configurations within the vehicle.
Implementation Method 1
the first material forms a non-conductive oxide layer under given atmospheric conditions
Implementation Method 2
the soldering alloy joins the first end portion of the first layer to the first end portion of the second layer
Implementation Method 3
an area of the section ultrasonically welded to another area of the section
Data Source
AI summary
An exemplary bus bar assembly includes a first layer and a second layer directly adjacent the first layer. The first layer and the second layer each have a section made of a first material and extending from a first end portion to an opposing, second end portion. The first and second end portions include a second material different than the first material. An exemplary method of forming a bus bar includes joining a section of a first bus bar layer and a section of a second bus bar layer to a respective first end portion and a respective second end portion. The sections of the first and second bus bar layers are made of a first material. The first and second end portions include a second material different than the first material.