Patent ID: 8821109

Claim:
A device for detecting the axial position of a rotary shaft of a rotary machine, the device comprising a target of ferromagnetic material placed at the end of said rotary shaft, an induction coil associated with a stationary magnetic circuit secured to a structure of the rotary machine and placed facing said target while leaving an airgap, and a power supply circuit for powering said induction coil, wherein the circuit for powering the induction coil comprises an AC voltage source connected between a first end of the induction coil and a zone situated at a reference voltage, at least one capacitor connected between said first end of the induction coil and a second end of the induction coil, and a detector device interposed between said second end of the induction coil and said zone situated at said reference voltage, in order to deliver on a line information about the magnitude of the current flowing between said second end of the induction coil and said zone situated at the reference voltage, said information representing the value of a modification x to the width of said airgap that presents a predetermined nominal value e 0 .