Scalable SMA Rotary Motor Using Parallel Tube Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rotary actuators in mechanical systems, particularly in aircraft, face challenges with large and complex mechanical drive trains due to limited torque generation by shape memory alloy (SMA) actuators, which require multiple gear sets and selectable transmissions to achieve desired torque levels, exceeding fabrication capabilities.
Innovation Solution
A scalable multi-element SMA rotary motor employing multiple SMA tubes in parallel, coupled with a ratcheting gear transmission and controlled heating to provide continuous rotational motion and multiplied torque, eliminating the need for extended mechanical drive trains and multiple gear sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If multiple gear sets and selectable transmissions are added to scale torque output, then torque generation is improved, but device complexity and weight increase
Solution Approach 1:
The system segments the torque generation function across multiple independent SMA tube actuators instead of using a single complex mechanical transmission system. Each tube can be independently controlled to contribute to the total torque output, eliminating the need for multiple gear sets and selectable transmissions while maintaining scalable torque capability.
2Force
If tube radius is increased to meet torque requirements, then torque generation is improved, but fabrication capability is exceeded
Solution Approach 1:
Instead of manufacturing one large-diameter SMA tube that exceeds fabrication capabilities, the system uses multiple smaller-diameter tubes that are within standard manufacturing capabilities. These tubes work together in parallel to achieve the required total torque output, making the system both manufacturable and scalable.
Solution Approach 2:
Multiple SMA tubes are arranged concentrically or in parallel configurations around a common output shaft, with each tube contributing to the total torque. This nested arrangement allows the system to achieve high torque output through cumulative effect of multiple manageable-sized tubes rather than requiring a single oversized tube.
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 enables increased torque and continuous rotary motion without added complexity, allowing for scalable torque output and reduced weight and complexity in actuation systems.
Implementation Method 1
Shape memory alloy (SMA) actuators have been employed for hinge line actuation
Implementation Method 2
SMA tube actuator output scales with tube radius to the third power and scales with length
Implementation Method 3
A ratcheting gear transmission couples the plurality of SMA tubes in parallel to a common output
Data Source
AI summary
A scalable multi-element shape memory alloy (SMA) rotary motor employs a plurality of SMA tubes. A ratcheting gear transmission couples the plurality of SMA tubes in parallel to a common output. A controller provides power to a plurality of heaters associated with each of the plurality of SMA tubes, sequentially heating selected heaters to provide continuous rotational motion of the common output.