Patent ID: 6539806
Filing Date: 2003-04-01
Classification: G01F,G01L

Abstract:
A fluid-load sensor comprising:A) a diaphragm assembly including: i) a flexible diaphragm forming first and second diaphragm faces; and ii) a permanent magnet that generates a permanent-magnet field and is mounted on the diaphragm for displacement with flexure thereof; B) a diaphragm support that so supports the diaphragm assembly as to enable the first diaphragm face to be exposed to an unknown fluid under pressure and to permit static diaphragm flexure indicative of that pressure; C) a diaphragm exciter, including a coil so disposed as to receive from the permanent magnet an axial magnetic flux that depends on the permanent-magnet displacement, that subjects the diaphragm to flexural excitation and resultant permanent-magnet oscillation by driving the coil with current that generates a coil magnetic field that applies a force to the diaphragm assembly and thereby causes an oscillatory signal in the coil in response to the permanent-magnet oscillation; D) a saturable magnetic circuit so positioned with respect to the coil and the permanent magnet as to affect the coil inductance and saturate in response to the permanent-magnet field to a degree that varies with the permanent-magnet displacement; E) a computation circuit responsive both to the coil inductance and to the frequency of the oscillatory signal to compute fluid load as a function of a coil-inductance-dependent quantity and an oscillatory-signal-frequency-dependent quantity.