The extreme conditions on Venus (460 °C and 92 atm) prevent the use of any of the existing science instruments outside of the lander. To transfer a sample into the lander, a pneumatic mechanism was conceived that could bring sample powder into the lander. The mechanism is critically dependent on the availability of valves that can operate at the conditions on Venus. The ability to perform the sample transfer will enable the use of instruments that require direct access to the sample, but cannot sustain Venus’ ambient environment.
The valve consists of a sealed enclosure with a number of openings/ports. The port openings are controlled by a fixed seat and a moving seal disk. The disk is mounted on a cantilevered flexure beam controlled by a set of piezoelectric actuators. In passive state, the beam preloads the disk against the seat and prevents the flow through the opening/ port. When the actuators are activated, the disk is moved away from the seat and the flow through the port opening is permitted.
Two piezoelectric actuators are mounted off-axis of the cantilevered beam to create a small arm with respect to the cantilevered arm pivoting point. This way, a small displacement on the piezoelectric stacks will generate a large displacement at the free end of the cantilevered beam. The seal disk is mounted at the free end of the cantilevered beam using a set of flexures that allows for adjusting the disk misalignment with the seat resulting from large variations during actuation or extensive temperature change. The two ports of the valve are the passages that allow the flow to pass through the valve, and the seal disk controls this flow.
The materials and the flexure stiffness for each implementation should be chosen depending on each application. For example, for a Venus application, the valve’s chamber and seat are made of ceramic materials, while the lever-arm is made of high-temperature metal. The ceramic seat is the interior surface of the valve body that will contact the disk on the lever arm to form a leak-tight seal. When the disk is moved away from the seat of the entry/exit port of the valve, it opens the valve. When it is returned by the flexure on the lever, the disk comes into contact with the seat and the valve is shut. The seat always remains stationary relative to the body of the valve. The piezoelectric stack actuators are selected from piezoelectric materials with a Curie temperature high above the working temperature.
This work was done by Mircea Badescu and Yoseph Bar-Cohen of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Refer to NPO-49276.
This Brief includes a Technical Support Package (TSP).
Piezoelectric Actuated Valve for Operation in Extreme Conditions
(reference NPO-49276) is currently available for download from the TSP library.
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Overview
The document presents a technical support package for a novel Piezoelectric Actuated Valve developed by NASA's Jet Propulsion Laboratory (JPL) for operation in extreme environmental conditions, particularly on celestial bodies like Venus, Titan, and Europa. The valve is designed to function effectively at temperatures ranging from -180ºC to 460ºC and pressures up to 92 atm, addressing the critical need for reliable mechanisms in harsh extraterrestrial environments.
The valve operates using piezoelectric stack actuators, which, despite generating large forces, produce small displacements in the microns range. To achieve significant valve movement, the design incorporates a cantilevered flexure beam that amplifies the small displacements from the actuators into larger movements at the valve's seal disk. This mechanism allows the valve to open and close, controlling the flow through its ports. In its passive state, the beam preloads the disk against a fixed seat, preventing flow. When activated, the actuators move the disk away from the seat, allowing flow through the valve.
The document emphasizes the valve's compact, lightweight, and low-power design, making it suitable for various applications, including pneumatic and hydraulic systems. The materials used in the valve's construction are selected based on the specific environmental conditions of the intended application. For instance, in Venus's extreme conditions, ceramic materials are used for the valve's chamber and seat, while high-temperature metals are employed for the lever arm.
The novelty of this valve lies in its ability to operate under extreme temperatures and pressures, fulfilling a critical need for future space missions that require sample transfer mechanisms capable of functioning in environments where existing instruments cannot operate. The valve's design and functionality are crucial for enabling scientific instruments that require direct access to samples, particularly in the context of planetary exploration.
Overall, this technical support package outlines the innovative design and potential applications of the piezoelectric actuated valve, highlighting its significance for future NASA missions and its broader implications for aerospace technology. The research was conducted under a contract with NASA, showcasing the collaboration between JPL and the National Aeronautics and Space Administration in advancing space exploration technologies.
