Microvalve

Abstract

A microvalve incorporating the invention includes a valve plate with a planar base and an extending pedestal, the pedestal having an upper valve surface. The planar base is enclosed by a rim which creates a valve recess between the rim and the pedestal. A cover plate is sealed to the rim and includes an outlet which is sealed by engagement with the valve surface of the pedestal. A support plate includes an enclosing rim that is sealed to a lower surface of the valve plate and creates a reference pressure enclosure. Both the support plate and valve plate are comprised of semiconductor material. A substrate is sealed to a lower surface of the support plate and creates a pressure recess between the substrate and the lower surface. A pump feeds a compressible fluid into both the valve recess and the pressure recess via a reference control subvalve positioned in a pathway between the reference pressure enclosure and the pressure recess. A control circuit opens the reference pressure valve to enable establishment of a reference pressure in the reference pressure enclosure; thereafter closes the reference pressure valve so that when pressure in the valve recess exceeds the reference pressure by a threshold level, the valve plate and pedestal are moved downwardly, allowing fluid flow out of the valve recess and through the fluid outlet. The control circuit further opens the reference subvalve to enable reestablishment of the reference pressure in the reference pressure enclosure, before a next pump cycle. A high voltage semiconductor circuit is shown which actuates the reference subvalve in accordance with control signals.