Shape Memory Alloy Valve Actuator With Thermal Encapsulation
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Solution Overview
Problem
Existing valve actuators for vapor compression systems, such as refrigeration systems, face challenges when operating under high pressure differences and varying temperatures, which can affect the performance of Shape Memory Alloy (SMA) materials, especially when refrigerant flows through the valve or the environment is not suited for SMA properties.
Innovation Solution
The use of an elongated Shape Memory Alloy element with encapsulation providing thermal resistance, allowing the SMA to maintain its properties and operate effectively by isolating it from ambient temperatures and refrigerant, while also providing mechanical support and displacement capabilities, with the encapsulation extending from one end of the SMA element to the other and capable of displacing with the SMA element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the Shape Memory Alloy element is exposed to refrigerant flow and varying ambient temperatures, then the valve can operate in different environmental conditions, but the SMA's thermo-mechanical properties deteriorate and energy consumption increases
Solution Approach 1:
The patent introduces an encapsulation layer as an intermediary between the SMA element and the external environment (refrigerant and ambient air). This encapsulation maintains a stable thermal environment for the SMA while allowing the valve to operate in various refrigeration conditions, thus reducing energy consumption by preventing unnecessary thermal cycling of the SMA material.
Solution Approach 2:
The encapsulation creates an inert thermal environment around the SMA element, isolating it from harmful thermal fluctuations caused by refrigerant flow and ambient temperature variations. This protected environment preserves the SMA's thermo-mechanical properties and reduces the energy required to actuate the valve under different operating conditions.
2Device complexity
If the Shape Memory Alloy element is directly exposed to refrigerant, then the valve structure is simplified, but the SMA's thermo-mechanical properties deteriorate due to direct cooling
Solution Approach 1:
The encapsulation serves as a mediator that allows the valve to maintain a relatively simple overall structure while protecting the SMA element from direct refrigerant exposure. The encapsulation layer is integrated into the valve body design, providing thermal protection without significantly increasing structural complexity, thus maintaining reliability of the SMA's thermo-mechanical properties.
3Adaptability or versatility
If the Shape Memory Alloy element operates in varying ambient temperatures, then the valve can function in different climate conditions, but the force provided by the SMA decreases
Solution Approach 1:
The encapsulation acts as a thermal intermediary that decouples the SMA element from ambient temperature variations. This allows the valve to function across different climate conditions while the encapsulation maintains consistent thermal conditions for the SMA, ensuring stable actuator force output regardless of external climate changes.
4Reliability
If the Shape Memory Alloy element is isolated from the environment through encapsulation, then the SMA's thermo-mechanical properties are maintained, but the device complexity increases
Solution Approach 1:
The patent merges the encapsulation function with the valve body structure, integrating the thermal protection layer into the existing valve design. This consolidation approach maintains the reliability of the SMA's thermo-mechanical properties while minimizing the increase in overall device complexity by combining multiple functions into a unified structure.
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 enhances the force provided by the SMA element, reduces energy consumption, and ensures the SMA's thermo-mechanical properties are maintained regardless of the surrounding temperature, preventing direct cooling by refrigerant and maintaining the SMA's intended operation.
Implementation Method 1
an actuator (6) comprising an elongated Shape Memory Alloy element (10)... the Shape Memory Alloy element... when forming part of the valve, having one end intended for being distant to a valve element (4) of the valve, and a second end intended for being proximate to the valve element
Implementation Method 2
an encapsulation (14) providing a thermal resistance between a temperature of the Shape Memory Alloy element (10) and a temperature of an environment of the encapsulation (14) and of the at least two extensions of the Shape Memory Alloy element (10)
Implementation Method 3
Deformation of the regulator spring can be varied by an electrical actuator in the form of a wire segment of a shape memory alloy through which electric current can be passed to vary its temperature and length
Data Source
AI summary
The invention relates to an actuator for a valve in a refrigeration system. The invention also relates to a valve with such actuator, and to a refrigeration system with such valve. The actuator comprises an elongated Shape Memory Alloy (SMA) element extending along two or more string-like extensions from a distant end to a proximate end in relation to a valve element of a valve. The SMA element, when forming part of the valve, may extend from the distant end to the proximate end connected to a housing of the SMA element, however, electrically insulated from the housing. An encapsulation may provide a thermal resistance, a thermal conductor and/or an electrical resistance between the SMA element and other elements or the surroundings of the SMA element.