A report discusses the continuing development of a normally closed, piezoelectrically actuated valve fabricated mostly by micromachining of silicon. The design and operation of the microvalve as described in the instant report are basically the same as those of the version described in “Improved Piezoelectrically Actuated Microvalve” (NPO-30158), NASA Tech Briefs, Vol. 26, No. 1 (January 2002), page 29. Major elements of design described in both the instant report and the cited prior article include (1) a pressure-aided sealing configuration that contributes to the desired normally-closed mode of operation and (2) knife-edge sealing rings that reduce susceptibility to trapping of particles and the consequent leakage. The report also presents additional information concerning details of design and fabrication, including, notably, additional justification for knife-edge (in contradistinction to blunt-cross-section) sealing rings: The knife-edge sealing rings provide greater sealing pressure at a given sealing force, thereby reducing the leak rate and even making it possible to achieve an adequate seal with a hard seat. A potential additional advantage of the knife-edge/hard-seat design is that contact pressures may be high enough to crush contaminant particles, thereby reducing the leakage attributable to contaminants.
This work was done by Eui-Hyeok Yang, Larry Wild, and Nishant Rohatgi of Caltech for NASA’s Jet Propulsion Laboratory. To obtain a copy of the report, “A Micro Valve for High Pressure Applications,” access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Mechanics category.
This Brief includes a Technical Support Package (TSP).
Improvements in a Piezoelectrically Actuated Microvalve
(reference NPO-30338) is currently available for download from the TSP library.
Don't have an account? Sign up here.