Determination of axial position and rotational position of body

Abstract

A sensor device for determining an axial position of a body (10) along a longitudinal axis (A) comprises: an excitation coil (23) extending around the longitudinal axis; one or more first detection coils (21) arranged in the vicinity of the excitation coil and in a first detection plane (P1); and one or more second detection coils (22) arranged in the vicinity of the excitation coil and in a second detection plane (P2). The excitation circuitry supplies a current having an excitation frequency to the excitation coil (23) to generate an excitation magnetic field distribution. The detection circuitry determines an axial position of the body at the excitation frequency based on signals from the first and second detection coils. The detection circuitry determines an axial position based on at least one difference between a signal from the first detection coil and a signal from the second detection coil. The rotational position of the body may be determined by detecting a stray magnetic field of a magnet carried by the body using at least two magnetic field sensors (24). The magnetic field sensor, together with the excitation coil and the detection coil, is arranged on a common printed circuit board (25).

Description

technical field [0001] The invention relates to a sensor arrangement for determining at least one of an axial position and a rotational position of a body, and to a corresponding method. Background technique [0002] WO 2004 / 048883 A1 discloses a sensor device for determining the position of a body along multiple degrees of freedom. The field coil extends around the electrical conductor. A plurality of pick-up coils or other magnetic field sensors are placed near the field coil at different angular positions along the circumference of the body. A high-frequency current is fed to the field coil, thereby generating a high-frequency magnetic field. Due to the high-frequency magnetic field, eddy currents are generated in the conductor. Eddy currents prevent high-frequency magnetic fields from entering most of the body. Therefore, the magnetic field lines are concentrated in the gap between the exciting coil and the body. The movement of the body will change the magnetic fie...

AI Technical Summary

Problems solved by technology

[0005] Regarding the determination of the axial position, the sensor proposed in WO 2006 / 074560 A2 has the same disadvantages as the axial position sensor disclosed in WO 2004 / 048883 A1 in that it requires the coil to be axially facing the target

Furthermore, regarding the determination of the rotational position, the sensor requires a notch near the pickup coil, which may interfere with the determination of the axial position

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