Position sensor and system

Abstract

A non-contacting position sensor has an exciting coil disposed in a plane and has a sensing coil located in an intersecting plane so that portions of the sensing coil are disposed symmetrically around a portion of the exciting coil in mutually inductive relation to that portion of the exciting coil. Ferrite means magnetically shield those sensing coil portions from other portions of the exciting coil and housing means are provided to mount the sensor so that those coil portions are conveniently positioned for relative movement with respect to magnetically permeable or electrically conductive inductance-modifying means on an object whose position is to be monitored. Movement of the inductance-modifying means as the object moves then modifies the mutual inductance between the respective sensing coil portions and the exciting coil portion so that, when the exciting coil is driven, the sensing coil provides a signal which is accurately and reliably representative of the object position. If desired, an additional sensing coil is disposed in a third plane intersecting the two previously noted planes to provide X-Y position sensing. The inductive position sensor is inexpensive, is independent of the rate of change of object position, and is adapted to provide a reversal in output signal polarity when the object moves through a selected position where digital output may be required. The sensor is versatile in application but is particularly shown in automotive control systems for regulating operating parameters of the automobile or its engine in response to change in position of an automotive component. The sensor is shown for use in sensing rotation of the engine crankshaft or distributor or linear movement of an automotive component such as a shock absorber.