SMA Actuator Subassembly for Bias-Free Fluidic Valve Bending
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Solution Overview
Problem
Existing fluidic valve actuation systems using shape memory alloy (SMA) wires face challenges in efficient stress application to channels for full closure and require additional control elements like biasing means or latching mechanisms, which complicate their design and functionality.
Innovation Solution
A simpler SMA wire actuator subassembly utilizing a bendable slender structure with a high slenderness ratio, where the SMA wire is connected to a base with terminals and a coupling mechanism that allows efficient bending without additional control elements, enabling multiple functions and reliable installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If SMA wire is looped around a flexible channel for controlling its diameter, then the valve can be actuated with simple structure, but high stress is applied to the channel when it needs to be fully closed
Solution Approach 1:
The patent introduces a resilient member (bellows) as an intermediary between the SMA wire and the valve channel. The SMA wire acts against the resilient member to drive the valve, rather than directly acting on the channel. This mediator absorbs and distributes the stress, preventing excessive stress concentration on the channel while still enabling effective valve actuation.
2Reliability
If SMA wire is coupled to a resilient member with biasing means for valve actuation, then reliable valve control is achieved, but additional control elements complicate the design
Solution Approach 1:
The patent extracts and eliminates the biasing means (spring) from the actuator assembly. The resilient member (bellows) itself provides the necessary elasticity and return force, replacing the need for separate biasing elements. This simplifies the overall structure while maintaining reliable valve control through the inherent properties of the bellows mechanism.
3Ease of operation
If SMA elements are connected with movable or deformable elements for fluidic valve actuation, then valve actuation is enabled, but reliable connection to current supply element becomes problematic
Solution Approach 1:
The patent segments the actuator into distinct functional components: a fixed base with current supply terminals, a resilient member (bellows) for mechanical movement, and an SMA wire for actuation. The base remains stationary and provides stable electrical connections, while the moving parts (bellows and SMA wire) are mechanically coupled but electrically isolated. This segmentation ensures reliable current supply to the SMA element while enabling the necessary mechanical movement for valve actuation.
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
This solution provides a lightweight, power-efficient, and cost-effective actuator subassembly that efficiently controls fluidic valves by translating SMA wire contraction into effective bending of the slender structure, enhancing reliability and flexibility in fluid control applications without the need for biasing means or latching mechanisms.
Implementation Method 1
a shape memory alloy wire (13) connected to said two terminals, said shape memory alloy wire (13) being actuated by Joule heating
Implementation Method 2
The central portion of the shape memory alloy wire (13) is hooked onto an arm (15)... said shape memory alloy wire (13) being actuated by Joule heating
Implementation Method 3
at least one bendable slender structure (12) whose bending is controlled by the shape memory alloy wire (13)... the bendable slender structure (12) having a height H with slenderness ratio ≥3:1
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention is inherent to an actuator subassembly comprising at least one bendable slender structure (12) mounted on a stationary body base (11) and carrying on a first surface an installation feature (17) and a plug (16) in its distal portion, the bending of the slender structure (12) being controlled by a shape memory alloy wire (13) through coupling means (15) located in its distal portion on a second surface opposite to the first surface. The invention also concerns a fluidic valve incorporating such an actuator subassembly.