Encapsulated SMA Valve Actuator for Stable Refrigerant Operation
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Solution Overview
Problem
Existing valve actuators for vapor compression systems, such as refrigeration systems, face challenges with Shape Memory Alloy (SMA) performance under high pressure differences and varying temperatures, where the SMA is exposed to refrigerant flow or unsuitable environmental temperatures, leading to potential cooling and disruption of thermo-mechanical properties.
Innovation Solution
The actuator design incorporates an elongated Shape Memory Alloy element with encapsulation providing thermal resistance and mechanical barriers, allowing the SMA to maintain its properties and operate effectively by isolating it from ambient temperatures and refrigerant, with extensions that increase force and reduce energy consumption, and can be integrated into the valve body without additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Shape Memory Alloy element is exposed to refrigerant flow and ambient temperatures, then the actuator can be integrated into the valve body without additional space, but the thermo-mechanical properties of the SMA are disrupted and energy consumption increases
Solution Approach 1:
The patent introduces an encapsulation layer as an intermediary between the Shape Memory Alloy element and the external environment (refrigerant flow and ambient temperatures). This encapsulation protects the SMA from direct thermal exposure while allowing the actuator to remain integrated within the valve body, thus maintaining thermo-mechanical properties without increasing energy consumption for heating.
2Reliability
If the Shape Memory Alloy element is isolated from ambient temperatures and refrigerant, then thermo-mechanical properties are maintained, but additional encapsulation structure is required
Solution Approach 1:
The patent employs a thin-film encapsulation structure that provides thermal isolation while minimizing structural complexity. The encapsulation is designed as a slender sheath that closely follows the SMA element, providing protection without adding significant structural complexity or volume to the actuator system.
3Force
If multiple extensions of the Shape Memory Alloy element are used, then force is increased and energy consumption is reduced, but the actuator requires more space within the valve body
Solution Approach 1:
The patent utilizes a multi-extension configuration where the Shape Memory Alloy element is arranged with multiple parallel extensions (at least two) instead of a single extension. This dimensional arrangement increases the total force output by distributing the actuation across multiple strands, while the slender profile of each extension allows them to fit within the existing valve body space without significant volume increase.
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 encapsulated SMA actuator ensures reliable operation under varying conditions, maintaining thermo-mechanical properties and reducing energy consumption, while minimizing exposure to refrigerant and ambient temperature influences, thus enhancing the valve's performance and longevity.
Implementation Method 1
an actuator (6) comprising an elongated Shape Memory Alloy element (10)
Implementation Method 2
the encapsulation (14) provides a thermal resistance between a temperature of the Shape Memory Alloy element (10) and a temperature of an environment of the encapsulation (14)
Implementation Method 3
using a force from the one wire strip for triggering the sealing member and using part of the valve body for conducting electrical current to the trigger actuator
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.