Bistable Valve Actuator Using SMA Impulses for Low-Power Holding
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Solution Overview
Problem
Existing valve actuation mechanisms require high energy to operate and often need a constant supply of current to maintain the valve in a specific position, which is inefficient and costly.
Innovation Solution
A bistable valve actuator system that uses a rocker movable between two stable states, coupled with a shape memory alloy (SMA) element and a recuperating spring, allowing the valve to switch between open and closed positions without continuous power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional valve actuation mechanism using SMA elements is used, then the valve can be actuated between open and closed positions, but a continuous supply of current is required to maintain the valve in the actuated position, resulting in high energy consumption
Solution Approach 1:
The system transitions from a static holding mechanism (continuous current) to a dynamic bistable mechanism where the valve can maintain its position in either open or closed state without continuous energy input. The rocker arm with two stable positions allows the valve to remain actuated through mechanical stability rather than continuous power supply.
Solution Approach 2:
Instead of continuous current supply, the system uses periodic or impulsive action through the shape memory alloy elements that are activated only when transitioning between states. Once the transition is complete, the mechanical bistable structure maintains the position without further energy input.
2Use of energy by moving object
If a bistable valve actuator mechanism is implemented, then energy consumption is reduced by eliminating continuous power supply, but the device complexity increases due to additional mechanical components
Solution Approach 1:
The rocker arm mechanism serves multiple functions: it acts as the actuation lever, provides the bistable mechanical structure, transmits force from the shape memory alloy elements, and maintains valve position through its inherent stability. This multi-functionality reduces the need for separate components for each function.
Solution Approach 2:
The patent combines the actuation mechanism and the position-maintaining mechanism into a single integrated bistable structure. The rocker arm with its two stable positions merges the function of actuation and holding, eliminating the need for separate motors, sensors, and control systems that would be required in a conventional system.
3Ease of operation
If SMA elements are used to actuate the valve, then precise control of valve position is achieved, but the cost of the actuator increases due to the specialized materials and continuous power requirements
Solution Approach 1:
The bistable mechanism is self-servicing in that it maintains its own position without external power input. Once the shape memory alloy elements initiate the transition to a stable state, the mechanical structure sustains itself, eliminating the need for continuous power supply and reducing operational costs.
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 system reduces energy consumption by utilizing elastic potential energy exchange between springs, allowing the valve to operate autonomously and efficiently, with reduced energy requirements.
Implementation Method 1
a shape memory alloy element coupled to the rocker wherein shape change of the shape memory alloy element under heat produces an impulse to move the bistable device out of the first stable state
Implementation Method 2
a resilient member configured to bias the rocker into each of the first and second stable states; the exchange of potential energy between the springs moves the actuator into the next stable state
Data Source
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AI summary
The present invention provides a method and apparatus for estimating one or more of the rate of fluid flow, the fluid pressure and the fluid viscosity of a fluid, the apparatus comprising a bistable device configured to be arranged in communication with a fluid; and an accelerometer arranged to detect motion of the bistable device.