SMA Diaphragm Valve for EMI-Resistant Variable Flow Control
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Solution Overview
Problem
Variable flow valves relying on solenoid elements face operational drawbacks such as complexity in electronics, susceptibility to electromagnetic interference, and vulnerability to dust and moisture, which degrade their performance.
Innovation Solution
A variable flow control valve utilizing a shape memory alloy wire coupled with pulleys and circuitry for controlled heating and cooling, allowing the diaphragm to switch between open and closed positions without complex electronics, and is designed with a curved pathway and elastic bias for precise fluid control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If solenoid elements are used to operate variable flow valves, then the valves can achieve automated flow control, but the device complexity increases and susceptibility to electromagnetic interference and environmental contamination occurs
Solution Approach 1:
The patent replaces the solenoid-based electromagnetic actuation system with a shape memory alloy (SMA) wire-based mechanical actuation system. The SMA wire contracts in response to temperature changes (heating/cooling cycles) to directly move the diaphragm, eliminating the need for complex solenoid electronics, electromagnetic fields, and associated control circuitry. This substitution maintains automated flow control through thermal cycling while dramatically simplifying the device structure and removing susceptibility to electromagnetic interference.
Solution Approach 2:
The patent utilizes the temperature-sensitive phase transition properties of shape memory alloy materials. By changing the thermal parameter (heating and cooling the SMA wire), the material undergoes a reversible phase transformation that causes it to contract and expand, thereby actuating the diaphragm valve. This parameter-based actuation method achieves automated flow control through simple thermal cycles rather than complex electromagnetic control.
2Extent of automation
If solenoid elements are used in variable flow valves, then automated operation is achieved, but reliability decreases due to susceptibility to dust, moisture, and electromagnetic interference
Solution Approach 1:
The patent replaces the solenoid electromagnetic system with a shape memory alloy wire system that actuates the diaphragm through thermal contraction. This mechanical/thermal system is inherently more resistant to dust and moisture contamination compared to electromagnetic solenoids with moving contacts and windings. The SMA wire has no electromagnetic fields to interfere with and no exposed electrical contacts vulnerable to contamination, thereby maintaining automated operation while significantly improving reliability in harsh environments.
Solution Approach 2:
The patent employs shape memory alloy, a specialized composite material with unique thermomechanical properties, to create an actuation system that is inherently resistant to environmental degradation. The SMA material combines metallic properties with shape memory characteristics, creating a robust actuator that maintains performance despite exposure to dust, moisture, and other contaminants that would degrade traditional solenoid components.
3Device complexity
If shape memory alloy wire is used to control the diaphragm, then device complexity is reduced and resistance to electromagnetic interference is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates a pre-tensioning mechanism for the shape memory alloy wire that is established during assembly. The wire is routed through guide elements and tensioning components that pre-set the initial tension and geometric configuration. This preliminary action during assembly ensures that subsequent thermal cycling of the SMA wire produces consistent, repeatable diaphragm actuation without requiring extremely tight manufacturing tolerances on individual components. The pre-established geometry compensates for variations in SMA wire properties.
Solution Approach 2:
The patent uses intermediate mechanical elements such as guide pulleys, tensioning springs, and geometric constraint features that mediate between the SMA wire contraction and the diaphragm movement. These intermediary components transform the complex nonlinear contraction behavior of the SMA wire into reliable, repeatable linear motion of the diaphragm. The intermediaries absorb manufacturing variations and ensure consistent valve operation without requiring ultra-precise manufacturing of each individual component.
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 provides a lightweight, quiet, and reliable valve that is resistant to electromagnetic interference and contamination, offering precise control and ease of manufacturing, suitable for various applications including aircraft fuel inerting and medical uses.
Implementation Method 1
The wire includes shape memory alloy
Implementation Method 2
circuitry is operably coupled to the wire and configured to cause the wire to be in one of the unheated and the unheated states
Implementation Method 3
an elastic element is configured to apply the bias to the diaphragm or the diaphragm has an elastic characteristic from which the bias arises
Data Source
Figure 1
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Figure 3~4
AI summary
A valve is provided and includes a valve body (110, 120) defining a pathway (130), a diaphragm (150) and a wire (160). The diaphragm is configured to assume first or second conditions in which the diaphragm blocks or permits fluid flow through the pathway, respectively. The diaphragm is biased toward assumption of the first condition. The wire is coupled to the diaphragm. The wire has an uncontracted length in an unheated state whereby the wire permits assumption of the first condition by the diaphragm due to the bias and a contracted length in a heated state whereby the wire pulls the diaphragm toward assumption of the second condition in opposition to the bias.