Patent ID: 6346806
Filing Date: 2002-02-12
Classification: F15B,G01B,G01D

Abstract:
A device for detecting the position of a moveably arranged control element of an actuating drive behind a housing wall made of a ferromagnetic material comprisinga housing wall made of a ferromagnetic material; a relatively moveable control element having a magnet disposed behind the housing wall, wherein the control element having the magnet is moved relative to the housing wall; an actuating drive supporting the moveable control element and the magnet for generating a magnetic field through the housing wall, wherein field lines of the magnetic field build up a main flux which progresses within said housing wall, whereby said main flux forms a magnetic remanence which is retained after the magnet has passed by and wherein the field of the magnetic remanence is directed along the movement axis of the magnet in accordance with the polarity, and builds up a leakage flux towards the front of the housing wall to the outside of the housing wall; a magnetic field sensor comprising a magnetic field sensor element located outside of said housing wall, wherein a leakage flux is directed in an opposite direction relative to the field direction of the main flux, and wherein the magnetic field sensor element detects the field direction of the leakage flux and, wherein the leakage field is superposed by the magnetic field of the magnet when the control element with the magnet passes by, and wherein the magnetic field sensor element is capable of registering the change in the polarity of the magnetic field; an evaluation electronic unit post-connected to the magnetic field sensor element for deriving a switching signal from the signal of the magnetic field sensor element in the electronic evaluation unit.