| 摘要 |
PURPOSE:To obtain the large displacement of a nozzle flapper by driving electrostriction elements by an AC signal whose frequency is changed in the vicinity of the mechanical resonant frequency of the electrostriction elements which are used for the nozzle flapper. CONSTITUTION:A voltage to frequency converter 4 outputs triangular waves having different frequencies corresponding to an input voltage Vi that is applied across input terminals 1a and 1b. A signal frequency of the voltage to frequency converter 4 when the input voltage Vi is large is set to that it approaches the mechanical resonant frequency of the electrostriction elements 6a and 6b of the nozzle flapper 5. The back pressure from a nozzle 12 is converted into an output pressure by a pilot valve 10, guided out from an output 13, and also applied to a pressure sensor 14. The output of the pressure sensor 14 is fed back to an operation amplifier 3. The ratio of completely closed time of the nozzle 12 is increased in proportion to the input voltage Vi, and the output pneumatic pressure of the pilot valve 10 is also increased. |
