Two-Zone SMA Fluidic Valve for Balanced Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SMA-actuated fluidic valves face challenges in managing pressure transitions during valve status changes, leading to uncontrolled output flow changes due to forces exerted on the valve plunger, especially in proportional valves.
Innovation Solution
A fluidic valve design with a shape memory alloy wire secured to a stationary surface acting on a deformable element, separating two zones with a fluid bypass connecting them, ensuring pressure balance between zones through apertures in the bypass channel, allowing for proportional control and preventing differential pressure issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a shape memory alloy wire is used to actuate a valve plunger, then compactness and ease of integration are improved, but pressure transitions during valve status changes cause uncontrolled output flow changes
Solution Approach 1:
The valve body is divided into two separate zones (first zone and second zone) that are fluidically isolated from each other. The shape memory alloy wire is located exclusively in the first zone, while the plunger and valve ports are in the second zone. This segmentation prevents pressure changes in the second zone from affecting the SMA wire actuation, eliminating the harmful feedback loop that caused uncontrolled flow changes.
Solution Approach 2:
A deformable element acts as an intermediary between the SMA wire in the first zone and the plunger in the second zone. This element transmits the actuation force across the fluidic boundary while maintaining zone isolation. Additionally, a fluid bypass with apertures serves as a mediator to equalize pressure between zones, preventing differential pressure from distorting the deformable element and causing unintended valve movement.
2Measurement precision
If the valve is designed with proportional control capability, then flow control precision is improved, but differential pressure forces on the plunger increase causing uncontrolled output flow changes
Solution Approach 1:
By segregating the actuation zone from the valve port zone, the system eliminates the harmful interaction between differential pressure and the proportional control mechanism. The SMA wire actuates the deformable element in the first zone without being subjected to the pressure differential that would otherwise cause uncontrolled plunger movement and compromise flow control precision.
Solution Approach 2:
A fluid bypass channel with apertures is introduced to hydraulically connect the first and second zones. This bypass equalizes the pressure between zones, preventing differential pressure from distorting the deformable element or exerting unwanted forces on the plunger, thereby maintaining stable proportional control.
3Stability of the object's composition
If a fluid bypass is added to balance pressure between zones, then pressure stability is improved, but device complexity increases
Solution Approach 1:
The deformable element serves multiple functions: it acts as the actuation interface for the SMA wire, seals between the two zones, and transmits force to the plunger. The bypass channel with apertures simultaneously provides pressure equalization and structural support. This multi-functionality minimizes the number of additional components needed, reducing the overall complexity increase.
Solution Approach 2:
The deformable element is implemented as a flexible membrane or bellows that can elastically deform to transmit actuation forces while maintaining fluidic isolation between zones. This flexible structure achieves pressure balancing and force transmission without requiring complex rigid mechanical linkages or additional sealing 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 solution effectively balances pressure between valve zones, preventing uncontrolled flow changes and ensuring precise control over valve operation, reducing the need for increased power and minimizing unintended valve closure or opening.
Implementation Method 1
the SMA material property of being characterized by a structural transition between two phases, namely the so-called Martensite phase which is stable at a lower temperature, and the so-called Austenite phase, which is stable at a higher temperature
Implementation Method 2
The shape memory alloy wire controlled shortening, usually by heating through current passage (Joule effect), is used to displace one or more element in the actuator
Implementation Method 3
A fluid bypass with a first aperture in the first valve zone and a second aperture in the second valve zone ensures the pressure balancing upon actuation of the valve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates in a first aspect to a balanced pressure two-zone fluidic valve (10) with a shape memory alloy control element wherein control of the valve (10) is achieved by deformation of a deformable element (14) upon actuation of a shape memory alloy wire (15) to move a plunger (16), and in a second aspect to the use of said valve for controlling a fluid flow.