Inductive differential pressure sensor

Claim 1

An inductive differential pressure sensor comprising: a rigid body delimiting an internal chamber; a flexible measuring diaphragm subdividing the chamber into half chambers which are sealed from each other; means for appying two pressures to be compared to respective ones of the two half chambers, a central zone of the diaphragm being suitable for being displaced by a value representative of the value of the difference between the two pressures along a reference direction perpendicular to a reference plane which is fixed relative to the body and which is defined by the general plane of the diaphragm in its rest position said body being at least partially symmetrical about said reference plane; and electromagnetic means for measuring the displacement by induction, said means comprising: two identical magnetic cores fixed to the central zone of the diaphragm and disposed symmetrically on either side thereof in each of the half chambers and mutually aligned parallel to the reference direction; two identical magnetic cores fixed to the central zone of the diaphragm and disposed symmetrically on either side thereof in each of the half chambers and mutually aligned parallel to the reference direction; two identical simple inductors fixed to the body in symmetrical positions on either side of the reference plane and mutually aligned parallel to the reference direction, each inductor surrounding a respective one of the cores so as to present an impedance which is a function of the position of the core relative to the inductor; wherein the body has means fixed therein for defining around each inductor a cavity which is sealed from the internal chamber, each of said cavities being maintained at substantially equal and constant pressure, said means being non-magnetic at least where they extend between the magnetic cores and the corresponding inductor windings, and wherein each inductor includes a frame within the corresponding cavity and is carried by the body inside the said cavity by means of a plurality of resilient tabs connected at one end to the frame and at the other end to the body; and electrical connection means for connecting the two inductors with means for measuring the difference of their impedances, whereby said difference is representative of the differential pressure and substantially independent of the temperature.