Inductive position sensor designed to measure the angular position of a shaft or the like

Abstract

An inductive position sensor designed to measure the angular position of a shaft or the like and includes a support on which are realized, on the one hand, a primary winding, and on the other hand, at least two secondary windings in phase opposition with respect to each other. Each secondary winding is defined by a set of at least two loops in phase with each other. The secondary windings are connected in series and each arranged symmetrically with respect to a middle line so as to form each time a pattern on either side of this middle line, the two patterns having a separation between them in the area of said middle line. An assembly including such a sensor and a target with two oppositely directed helices.

1 . A method for noncontact measurement of the angular position of a shaft, comprising:
 providing the outer surface of the shaft with two helices of opposite directions, the helices being distant from one another, along the angular measurement range, by a predetermined distance which is a function of the estimated axial displacement of the shaft,   furnishing an inductive position sensor with one primary winding and at least two secondary windings, one secondary winding being defined by a set of at least two loops in phase with each other,   arranging the loops of each secondary winding facing the helices so that when the angular position of the shaft varies by a value, then on the one hand for one secondary winding the variation in flux induced in the loops facing one helix is identical to that of the flux induced in the loops facing the other helix, and on the other hand the variation in flux induced in the loops of one secondary winding facing one helix is identical but opposite the variation in flux induced in the loops of the other secondary winding, the loops facing one helix being separated from the loops facing the other helix by a distance corresponding to the distance separating the helices along the angular measurement range,   exciting the primary winding and measuring the signal on the secondary windings, and   determining the angular position of the shaft, the measured signal corresponding to an angular value of the position of the shaft independent of an axial displacement of the latter.   
     
     
         2 . The method as claimed in  claim 1 , wherein it also makes it possible to measure an axial displacement of the shaft and further comprises:
 providing the sensor with at least two additional secondary windings,   arranging the loops of each additional secondary winding facing the helices so that when the angular position of the shaft varies by a value, then on the one hand for one secondary winding the variation in flux induced in the loops facing one helix is identical but opposite to that of the flux induced in the loops facing the other helix, and on the other hand the variation in flux induced in the loops of one secondary winding facing one helix is identical to that of the flux induced in the loops of the other secondary winding, the loops facing one helix being separated from the loops facing the other helix by a distance corresponding to the distance separating the helices along the angular measurement range measuring the signal on the additional secondary windings, and   determining the axial position of the shaft, the signal measured in the area of the additional secondary windings corresponding to position of the shaft independent of the angular position of the latter.