In line hall effect detector and method of sensing angular position particularly suited for electrical rotary actuator
AssigneeWoodward Governor Company
InventorJon S. Pointer
Life of this patent
Estimating the term…
Abstract
An apparatus for sensing rotary position that is particularly suited for electrical rotary actuators. The sensing apparatus comprises a magnet and a hall effect detector, both of which are arranged along the axis of rotation. The hall effect detector senses the angle of the return loop of magnetic flux lines from the north to the south pole of the magnet. When the magnet rotates relative to the hall effect detector, the angle of the magnetic flux lines changes which is detected by the hall effect detector. The arrangement of the magnet and the hall effect detector on the shaft axis of a rotary actuator avoids the magnetic flux line interference that is naturally produced by electrical actuators.
Claims21
An apparatus for sensing angular position, comprising:
- a magnet arranged on an axis having a north pole and a south pole, the magnet emitting a magnetic field having magnetic flux lines traveling in a return loop from the north to the south pole, the return loop intersecting the axis;
- and
- a sensor responsive to the magnetic field axially offset from the magnet on the axis sensing an angle of magnetic flux lines traveling along the return loop, wherein relative rotation between the magnet and the sensor causes the magnetic flux lines impinging upon the sensor to change angle, the sensor having an output related to the angle of magnetic flux lines and corresponding to relative angular positions between the magnet and the sensor.
An electrical actuator including an apparatus for sensing rotary position thereof, comprising:
- a stator comprising a lamination stack and wire coils;
- a rotor adapted to be rotated by the stator comprising an output shaft carried by the stator for rotation about an axis;
- a magnet fixed to an end of the output shaft, the magnet having a north pole and a south pole, the magnet emitting a magnetic field having flux lines traveling in a return loop from the north to the south pole, the return loop intersecting the axis;
- a sensor responsive to the magnetic field in a stationary position on the stator axially spaced from the magnet along the axis, the sensor sensing an angle of magnetic flux lines traveling along the return loop, wherein when the shaft rotates, the magnetic flux lines rotate with the magnet to impinge upon the sensor at a different angle, the sensor having an output related to the angle of the magnetic flux lines and corresponding to position of the shaft.
An apparatus for sensing rotary position, comprising a magnet and a hall effect detector, the magnet in axial spaced relation to the hall effect detector relative to an axis of rotation, the magnet having north and south poles spaced apart radially with a line between the poles intersecting the axis, wherein the hall effect detector senses relative rotation between the hall effect detector and the magnetic about the axis.
The apparatus of claim 16 wherein the north pole and south pole lie along a line perpendicular to the axis, such that the magnet produces a return loop of magnetic flux lines that intersect the axis perpendicularly.
The apparatus of claim 20 wherein the rotary actuator is electrical the stator including a lamination stack and coils surrounding the axis, the rotor having permanent magnets mounted to the shaft, the actuator having a magnetic leakage field having magnetic flux lines extending axially out of the end of the shaft, the sensor being arranged so as to avoid sensing the magnetic flux lines of the magnetic leakage field.
A method of determining rotary position in a rotary actuator comprising a stator carrying a rotor for rotation about an axis, comprising:
- emitting a magnetic field from the rotor, the magnetic field having magnetic flux lines traveling in a return loop from the north pole to the south pole, the return loop intersecting the axis perpendicularly;
- sensing an angle of magnetic flux lines traveling along the return loop at a fixed position on the axis, wherein when the rotor rotates, the angle of the magnetic flux lines changes;
- and
- outputting a signal in response to the sensed angle of magnetic flux lines such that the signal corresponds to a rotary position of the rotor.
Dependencies are inferred from the claim text.