Shape Memory Valve Actuator for Shock-Free Spaceflight Sealing
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Solution Overview
Problem
Valves in space propulsion systems, particularly pyrotechnically actuated ones, face reliability issues due to limited lifespan and potential for inducing hydraulic and structural shock loads, which can be problematic especially towards the end of a satellite's service life.
Innovation Solution
A valve arrangement using a one-way effect shape memory actuator integrated into the valve assembly, activated by a heating element, which expands to press against a harder sealing seat, ensuring a high sealing effect and remaining permanently closed after actuation, eliminating the need for stored chemical energy and reducing shock loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pyrotechnic actuators are used for valve actuation, then the valve can be actuated quickly, but the actuator lifespan is limited to a few years and reliability decreases towards the end of satellite service life
Solution Approach 1:
The patent replaces the pyrotechnic actuation system with a shape memory alloy actuator system. The shape memory alloy undergoes a phase transformation from martensitic to austenitic state when heated, producing mechanical displacement to actuate the valve. This substitution eliminates the lifespan limitations of pyrotechnic actuators while maintaining reliable actuation capability throughout the satellite's extended service life.
Solution Approach 2:
The patent utilizes the temperature-dependent phase transformation parameter of the shape memory alloy. By heating the alloy above its transformation temperature, it transitions from a soft martensitic state to a rigid austenitic state, generating the force needed for valve actuation. This parameter change enables repeated reliable actuation without the degradation issues of pyrotechnic systems.
2Ease of operation
If pyrotechnic actuators are used for valve actuation, then the valve can be actuated in a one-time manner, but hydraulic and structural shock loads are induced
Solution Approach 1:
The patent employs a sealing piston with a sealing element that dynamically adapts to the valve seat during actuation. The sealing piston is displaced by the shape memory alloy actuator and maintains continuous contact with the valve seat through elastic deformation of the sealing element, enabling controlled one-time actuation without inducing shock loads.
Solution Approach 2:
The sealing element on the sealing piston provides inherent cushioning through its elastic properties. This elastic deformation absorbs and distributes the forces during valve actuation, preventing the transmission of shock loads to the hydraulic system and structural components while maintaining the one-time actuation capability.
3Reliability
If a sealing piston made of hard material is used, then the sealing effect is improved, but the sealing piston cannot undergo plastic deformation to ensure high sealing effect
Solution Approach 1:
The patent applies different material properties to different parts of the sealing system. The sealing piston body is made of a ductile material that can undergo plastic deformation, while the sealing element on its surface is made of a harder material for effective sealing contact. This local differentiation of material properties allows the sealing piston to both deform plastically for adaptation and provide high sealing effect through the harder sealing element.
Solution Approach 2:
The sealing system utilizes a composite structure where a ductile sealing piston body is combined with a harder sealing element. The ductile body provides deformation capability for adaptation to the valve seat, while the harder sealing element ensures effective sealing contact. This composite approach resolves the contradiction between ductility and sealing effectiveness.
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 reliable, long-term operational valve that can be actuated independently of the satellite's service life, avoiding hydraulic and structural shock loads, and ensuring a high sealing effect without the limitations of pyrotechnic actuators.
Implementation Method 1
activated by a heating element, which expands to press against a harder sealing seat
Implementation Method 2
The actuator is a one-way effect shape memory actuator that is upset in the martensitic state along a longitudinal axis of the actuator
Implementation Method 3
experiences a change in length as a result of activation of the heating element when a predetermined transformation temperature is reached
Data Source
Figure 1~2
AI summary
The invention relates to a valve arrangement, particularly for a space component, for single actuation, comprising an inlet (1) and an outlet (2), and an actuator (5) that can be actuated by a heating element (7). In a non-actuated state of the actuator (5), flow is permitted between the inlet (1) and the outlet (2). The actuator (5) is a one-way shape-memory actuator, which, in its martensitic state, is compressed along a longitudinal axis and integrated into the valve arrangement. Upon activation of the heating element (7) at a predetermined transformation temperature, the actuator (5) undergoes a change in length, which gradually presses it against a sealing seat (6) formed at the inlet (1) or the outlet (2).