Patent ID: 7132825
Filing Date: 2006-11-07
Classification: G01D

Abstract:
1. A device for detecting movement of an object which contains ferromagnetic material and can move along a path, such device includes a magnetic circuit generator which has a first and a second elongated and straight cores made of ferromagnetic material, an excitation coil and a measuring coil, said generator is connected to a detection unit adapted to detect a reluctance variation produced in the circuit by the movement of the object and to deduce a position of the object therefrom, which device is characterised in that the magnetic circuit generator comprises a first and a second open magnetic circuit transformers, said first transformer including the first core and the second transformer including the second core, said transformers being juxtaposed and each having an axis that extends through its respective core, said axes extending substantially perpendicularly to said path, said excitation coil comprising a connection in series of two coils that form the primary coils of the first and second transformers, and said measuring coil comprising a connection in series of two coils that form the secondary coils of the first and second transformers, said secondary coils being connected in phase opposition and a capacitor being in parallel connection with the secondary coils; characterised in that the transformers are separated from the object by a metal wall that is a poor conductor of electrical current.