Bus Bar Assembly Using Shape Memory Alloy for Thermal Expansion Control
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Solution Overview
Problem
Conventional electrical distribution systems face challenges with thermal expansion and heat management, leading to inefficient heat delivery and reduced lifespan due to multiple thermal interfaces and mismatched thermal expansion properties between components.
Innovation Solution
A bus bar formed from a combination of traditional materials and shape memory alloys, such as nitinol wire embedded in an aluminum matrix, with additive manufacturing techniques, allowing for reduced thermal expansion and direct heat delivery through the use of exothermic soldering and minimal thermal interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bus bar materials (copper, aluminum) are used, then electrical conductivity is maintained, but thermal expansion mismatch and heat management efficiency deteriorate
Solution Approach 1:
The patent employs a composite bus bar structure consisting of a shape memory alloy substrate (e.g., nitinol wire mesh) embedded with traditional conductive materials (copper, aluminum). This composite construction allows the bus bar to exhibit reduced thermal expansion characteristics from the shape memory alloy while maintaining electrical conductivity through the embedded copper or aluminum layers, thereby resolving the contradiction between thermal expansion compatibility and heat delivery efficiency
Solution Approach 2:
The patent utilizes the phase transformation properties of shape memory alloys to dynamically change the thermal expansion parameters of the bus bar. By leveraging the unique thermomechanical behavior of shape memory materials, the bus bar can adapt its dimensional stability characteristics in response to temperature variations, improving thermal expansion compatibility without compromising electrical performance
2Reliability
If multiple thermal interfaces are used to manage thermal expansion, then component compatibility is improved, but heat delivery efficiency and lifespan deteriorate
Solution Approach 1:
The patent extracts and eliminates unnecessary thermal interfaces by directly bonding the bus bar to the circuit board using shape memory alloy-based adhesives or intermetallic compounds. This removal of intermediate thermal interface layers reduces thermal resistance and improves heat delivery efficiency, while the shape memory alloy provides the necessary compliance to maintain component compatibility through its superelastic and thermal expansion properties
Solution Approach 2:
The patent creates a homogeneous thermal path by eliminating discontinuous thermal interfaces between the bus bar and circuit board. The shape memory alloy substrate, when used as an adhesive or bonding layer, provides a continuous thermal pathway that maintains both thermal contact and mechanical compliance, thereby extending bus bar lifespan through improved heat dissipation without sacrificing component compatibility
3Ease of manufacture
If traditional bus bar designs are used, then manufacturing simplicity is maintained, but thermal management performance and lifespan deteriorate
Solution Approach 1:
The patent merges multiple functions into a single bus bar structure: the shape memory alloy substrate provides both structural support and thermal expansion compensation, while embedded copper or aluminum layers provide electrical conductivity. This integrated design achieves superior thermal management performance without significantly complicating the manufacturing process, as the composite structure can be fabricated using established metallurgical techniques
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 achieves efficient heat management and extended lifespan by balancing thermal expansion and reducing unnecessary thermal interfaces, while maintaining electrical conductivity and mechanical strength.
Implementation Method 1
The substrate framework is formed from a memory metal, such as a shape memory alloy, and has a contracted configuration in response to heat
Implementation Method 2
The substrate framework contracts in response to heat, balancing the thermal expansion of the bus bar
Implementation Method 3
direct heat delivery through the use of exothermic soldering and minimal thermal interfaces
Implementation Method 4
direct heat delivery through the use of exothermic soldering
Implementation Method 5
exothermic soldering
Data Source
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AI summary
A power distribution system element formed via an additive manufacturing technique (101), such as applying a conductive material to a memory metal substrate, are discussed herein. In operation (e.g. in response to delivering current through the distribution system), the memory metal contracts while the conductive material expands. The result is distribution system element having reduced thermal expansion, which can be net zero coefficient of thermal expansion.