CONTACTLESS POSITION SENSOR AND CONTACTLESS POSITION SENSOR SYSTEM

摘要

The invention relates to an improved contactless position sensor and a system incorporating same. Such a contactless position sensor comprises at least two sensor coils each comprising a magnetic permeable core and windings defining a coil axis. The at least two sensor coils are arranged with the coil axes essentially in parallel to each other. An electrical circuit of the sensor drives a predetermined alternating current within each of the at least two sensor coils and determines a high frequency voltage component of a voltage across each of the at least two sensor coils. The predetermined alternating current includes a low frequency current component, and a high frequency current component. The electrical circuit detects the position of a ferromagnetic target by subtracting from each other amplitude levels of the high frequency voltage components of two of the determined voltages and by comparing the subtraction result to a pre-determined reference pattern.

主权项

1. A contactless position sensor for detecting a position of a ferromagnetic target by way of deflection of an external magnetic field Hext, comprising:
at least two sensor coils each comprising a magnetic permeable core and windings surrounding the magnetic permeable core defining a coil axis; wherein the at least two sensor coils are arranged with the coil axes essentially in parallel to each other, and with one end of each of the at least two sensor coils facing a space for the ferromagnetic target to move across with respect to each of the at least two coil axes; and an electrical circuit for driving a predetermined alternating current within each of the at least two sensor coils and for determining a high frequency voltage component of a voltage across each of the at least two sensor coils; wherein the predetermined alternating current includes a low frequency current component set to drive each of the at least two sensor coils into a saturation state, and a high frequency current component set for measuring the impedance of each of the at least two sensor coils; and wherein the electrical circuit is adapted to detect the position of the ferromagnetic target by subtracting from each other amplitude levels of the high frequency voltage components of two of the determined voltages across the respective two sensor coils, and by comparing the subtraction result to a pre-determined reference pattern.