Electrostatically controlled, pneumatically actuated microvalve with low pressure loss

This paper describes a microvalve to control liquefied gas in a micro fuel reforming system. To realize both high pressure leak tolerance and low pressure loss, a main valve is pneumatically actuated by the pressure of the liquefied gas itself, and its pneumatic actuation is controlled by two electrostatic sub-valves. The fabricated microvalve was tested in terms of pressure loss in the open state, leakage in the closed state, driving voltage, and response time. The pressure loss was close to the theoretical value, which was sufficiently low for the application. The apparent leakage was not detected until the input pressure reached 150 kPa (gage). The driving voltage of the sub-valve was 30-40 V. The response time from the closed to the open state is expected to be less than 200 ms. The experimental results suggest that all the required functions such as low pressure loss, electrostatic actuation and leak proof operation can be realized. (c) 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.