Shape Memory Alloy Impulse Actuator for Large Displacement
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Solution Overview
Problem
Conventional methods for imparting kinetic energy and displacing a body over a large distance are limited by mass, packaging, complexity, and robustness, with shape memory alloy (SMA) actuators only providing up to 8% displacement in a single actuation cycle, requiring complex transmissions to achieve greater displacements.
Innovation Solution
An apparatus utilizing a shape memory alloy wire or dielectric elastomer actuator that undergoes a reversible change to transfer kinetic energy to a body, allowing it to travel a distance greater than the actuator's own displacement, reducing mass, packaging requirements, complexity, and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If SMA actuators are used to directly drive a body, then mass and packaging are reduced, but displacement is limited to at most 8% of the wire length in a single actuation cycle
Solution Approach 1:
The patent employs periodic actuation cycles where the SMA wire is rapidly activated to generate impulse, then allowed to relax and be reset. This periodic on-off cycling enables the system to achieve large cumulative displacements through multiple short actuation strokes rather than requiring a single long stroke, thereby overcoming the 8% displacement limit without adding complex transmission mechanisms.
Solution Approach 2:
The system utilizes dynamic impulse generation through rapid activation of the SMA wire, creating high-speed motion that transfers momentum to the body. The dynamic nature of the impulse allows the body to coast beyond the wire's physical displacement distance, achieving larger overall displacements while maintaining simple direct-drive architecture.
2Length of moving object
If complex transmissions and amplifying mechanisms are employed to achieve large displacements, then displacement is increased, but mass, packaging, and complexity are re-introduced
Solution Approach 1:
The patent extracts and eliminates complex transmission mechanisms (gears, levers, pulleys) from the system, relying instead on the direct impulse from the SMA wire to propel the body. By taking out these intermediate mechanical components, the system achieves large displacements through pure impulse-driven motion, thereby reducing mass and packaging requirements while maintaining the ability to achieve greater-than-wire-length displacements.
3Length of moving object
If complex transmissions and amplifying mechanisms are employed to achieve large displacements, then displacement is increased, but packaging requirements are re-introduced
Solution Approach 1:
The patent removes complex transmission and amplifying mechanisms from the system, achieving large displacements through direct impulse transfer from the SMA wire to the body. This extraction of unnecessary components significantly reduces the volume and packaging space required, as the system relies on simple direct-drive architecture with minimal moving parts.
Solution Approach 2:
By using periodic rapid actuation cycles, the system achieves cumulative large displacements through multiple short strokes rather than requiring long continuous travel mechanisms. This approach minimizes the space needed for transmission components and allows for compact packaging of the actuator system.
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
Enables large displacements with reduced mass, packaging, complexity, and noise, achieving kinetic energy transfer beyond the actuator's direct displacement, suitable for various applications including sunshade deployment, energy absorption, and piston articulation.
Implementation Method 1
the invention utilizes the shape memory effect in SMA to impart kinetic energy to a body or mass with which it is in physical contact
Implementation Method 2
an active-material actuator, such as a shape memory alloy wire or dielectric elastomer diaphragm or tendon
Data Source
AI summary
An apparatus for and method of displacing a body, such as a projectile, piston, or the distal edge of a sunshade cover or energy absorbing honeycomb matrix, utilizing momentum generated by the rapid actuation of an active material element, such as a Martensitic shape memory alloy wire.