Rotationally Symmetrical Speed Sensor with Detection of Direction of Rotation

Abstract:
In many applications with magnetic field-based speed sensors and passive target wheels, the rotatability of the sensor due to rotational symmetry is an important application criterion; likewise, tooth mapping independent of the air gap and, increasingly, detection of the direction of rotation are frequently required. The rotational symmetry can preferably be achieved by a single sensor element on the axis of rotation. For the detection of the direction of rotation, an asymmetrical shape of the teeth of the sensor wheel is then required. In the concept proposed here, a tooth mapping that is almost independent of the air gap is also achieved - at least for one tooth edge.