SMA Actuator Assembly With Deformable Heat Transfer Cooling
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Solution Overview
Problem
Existing SMA actuator assemblies face challenges in efficiently cooling SMA wires without impeding the relative motion of components, leading to slower response times and limited actuation frequencies.
Innovation Solution
Incorporating a heat transfer material between the first and second parts of the SMA actuator assembly, which is configured to deform and transfer heat while allowing relative movement, with properties that minimize shear deformation and enhance cooling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat transfer material is arranged around SMA wire to improve cooling, then cooling efficiency is improved, but relative movement of components may be impeded
Solution Approach 1:
The heat transfer material is configured to deform so as to allow relative movement of the first and second parts. This flexible deformation capability enables the material to adapt to component movement while maintaining thermal contact with the SMA wire, thus resolving the contradiction between improved cooling efficiency and maintained ease of operation.
2Temperature
If heat transfer material is made rigid to enhance heat transfer, then cooling rate increases, but shear deformation resistance increases causing excessive resistance to movement
Solution Approach 1:
The heat transfer material is designed with specific mechanical properties including a shear modulus of less than 100 kPa (preferably less than 10 kPa, further preferably less than 1 kPa). This parameter optimization allows the material to maintain adequate heat transfer capability while minimizing resistance to relative movement through controlled shear deformation.
3Temperature
If heat transfer material is arranged to fully encompass SMA wire, then heat transfer surface area is maximized, but complexity of assembly increases
Solution Approach 1:
The heat transfer material is arranged between the first and second parts and around at least a portion of the SMA wire, combining structural support and thermal management functions into a single integrated component. This merging approach maximizes heat transfer surface area while avoiding the complexity of separate cooling mechanisms.
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 heat transfer material improves cooling efficiency, enabling faster response times and higher actuation frequencies without hindering the relative motion of components.
Implementation Method 1
a heat transfer material arranged between the first and second parts and around at least a portion of the SMA wire so as to transfer heat between the SMA wire and first and second parts
Implementation Method 2
SMA wire contracts when it is heated, for example by applying appropriate electrical power signals to the SMA wire
Implementation Method 3
the heat transfer material is configured to deform so as to allow relative movement of the first and second parts. The heat transfer material may undergo shear deformation when the first and second parts are moved relative to each other
Data Source
AI summary
An SMA actuator assembly (2) comprising: first and second parts (4,6) that are movable relative to each other; and an SMA wire (10) arranged, on contraction, to drive relative movement of the first and second parts; and a heat transfer material (30) arranged between the first and second parts and around at least a portion of the SMA wire so as to transfer heat between the SMA wire and first and/or second parts, wherein the heat transfer material is configured to deform so as to allow relative movement of the first and second parts.