Differential pressure transducer

Abstract

An improved differential pressure transducer includes a chamber divided by a non-magnetic, electrically conductive measuring diaphragm supported between two support members each of which has a cavity covered with a seal diaphragm. Differential pressure of an incompressible fluid medium to be measured and transduced is applied to the measuring diaphragm, the displacement of which is detected by magnetic core detection coils. The detection coil magnetic cores are joined to the support members through spaces of magnetic material having temperature dependent characteristics opposite to that of the cores to thus neutralize temperatures induced effects. The inductance change in the detection coil upon displacement of the measuring diaphragm provides an electrical signal corresponding to the differential pressure through the provision of an oscillation circuit supplying AC signals to the coils, a control circuit controlling, to a constant value, the sum of the currents in the coils and a circuit for deriving the current differences as an output signal. Advantageously, the oscillation frequency of the output signal of the oscillation circuit is selected to be approximately the reasonant frequency of the detection coils.