Current to pressure converter apparatus

Claim 1

A current to pressure converter apparatus including: means providing an input electrical signal; circuit means responsive to said input electrical signal to provide an output electrical signal; a mounting block; piezoelectric flapper means responsive to said output electrical signal including a flexture element having one end mounted on said block and having one free end, the amount of flexture of the free end being a function of the output electrical signal; a housing mounted on said block having a movable wall defining a chamber; a source of controlled fluid under pressure connected to said chamber; a nozzle leading from said chamber, said free end being adjacent said nozzle to control discharge of fluid through the nozzle and control pressure in the chamber, and thereby control position of the movable wall as a function of the flexture of the flexture element; fluid amplifier means mounted on said block adjacent said housing and having an outlet and including a valve spool movable to position to adjust the fluid pressure at the outlet of the fluid amplifier means; bias means to urge the valve spool in a first direction; means to mechanically couple the movable wall directly to said valve spool so movement of the movable wall in a second direction under changes in pressure causes the valve spool to move against the bias means thus controlling the position of the valve spool as a function of the amount of flexture of the flexture element and therefore of the output electrical signal; and pressure feedback means connected directly to sense the fluid pressure at the output to provide an electrical feedback signal to said circuit means which is a function of the fluid pressure at the outlet to achieve a balance in the circuit means upon changes in the input signal.