Patent ID: 6593734
Filing Date: 2003-07-15
Classification: G01B,G01D

Abstract:
A magnetic position sensor provided with a stator and at least one part that is movable in at least one direction OX, with a useful stroke Xc, Xc representing, in a case of a rotary sensor, a width of an angular arc traveled by the movable part over a mean radius of a magnetized part and, in a case of a linear sensor, a stroke of the movable part in a direction contained in a central plane of a primary air gap,the stator being composed of at least two ferromagnetic pieces of soft magnetic material defining at least one secondary air gap in which is housed at least one magnetosensitive probe for measuring variation of induction in the secondary air gap, each stator ferromagnetic piece having a length Xs equal to at least Xc in the direction OX, Xs being measured over the mean radius of the magnetized part in the case of the rotary sensor, or measured in a direction contained in the central plane of the primary air gap in the case of the linear sensor, each stator ferromagnetic piece being aligned, for a linear sensor, either in a given plane surface parallel to OX or in a given cylindrical surface whose axis is OX and, for a rotary sensor, in a given cylindrical surface whose axis corresponds to an axis of rotation of the movable part, the sensor being provided in addition with at least one movable part equipped with the at least one movable yoke of soft magnetic material and at least one magnet joined to that at least one movable yoke, each movable magnetic part being displaced parallel to the ferromagnetic stator pieces at a constant minimal distance, the at least one magnet having its poles parallel to the ferromagnetic pieces of the stator, wherein the at least one magnet is partly embedded in a cavity situated substantially at a center of the movable yoke at a depth e such that 0.1 Lthe at least one magnet being displaced parallel to the ferromagnetic stator pieces at a constant minimal distance and having magnetization perpendicular to OX and a length equal to at least Xc in the direction of displacement OX, Xc being measured over the mean radius of the magnet in a case of a magnet of semiannular form or a length in a case of a straight magnet.