Electrically activated normally closed diaphragm valves

Abstract

Thermal actuation of integrated valve structures is attractive due to the relative simplicity of the actuator design, the moderate activation time possible, the relatively low total power required, and the ability to fully integrate the actuator with the flow control component. Of the many thermal actuation schemes, the use of bimetallic elements is preferred, particularly when a low cost, fully integrated structure is desired. Bimetallic structures allow both normally-open and normally-closed valves by varying the boundary conditions at the support for the actuator, which is difficult to achieve with many alternate technologies. One such valve has been designed to provide fully proportional control of flows in the range of 0-150 cc min-1 at input pressures between 1 and 50 PSIG. The valves are batch fabricated using silicon micromachining techniques. By combining these valves with pressure or flow sensing elements, closed loop pressure or flow control is easily accomplished.