Method for straightening the magnetic field of a magnet and a position sensor incorporating the magnet

A sensor system for sensing rotational position of a rotatable component that is rotatable about a rotational axis, the sensor system comprising:

• a Hall sensor;
• and
• the magnet assembly disposed on the rotatable component and at a first predetermined distance from the Hall sensor, the magnet assembly comprising:
• a magnet, the magnet having an outer peripheral surface and a flat end face, the flat end face disposed perpendicular to the rotational axis, the rotational axis extending through a center of the flat end face;
• and
• a ferromagnetic structure having an inner peripheral surface, the ferromagnetic structure surrounding the magnet and extending, toward the Hall sensor, a second predetermined distance beyond the flat end face,
• wherein:
• the magnet exhibits a first variation in magnetic field orientation at least at the first predetermined distance from the flat end face;
• the magnet assembly exhibits a second variation in magnetic field orientation at least at the first predetermined distance from the flat end face;
• and
• the first variation in magnetic field orientation is greater than the second variation in magnetic field orientation.

A method for straightening the magnetic field of a magnet, the method comprising the steps of:

• providing a magnet, the magnet having an outer peripheral surface and a flat end face, the flat end face disposed perpendicular to an axis that extends through a center of the flat end face;
• providing a ferromagnetic structure having an inner peripheral surface;
• and
• surrounding the magnet with the ferromagnetic structure such that the ferromagnetic structure (i) is fixedly mounted relative to the magnet and (ii) extends a first predetermined distance beyond the flat end face, to thereby produce a magnet assembly,
• wherein:
• the magnet exhibits a first variation in magnetic field orientation at the flat end face,
• the magnet assembly exhibits a second variation in magnetic field orientation at the flat end face, and
• the first variation in magnetic field orientation is greater than the second variation in magnetic field orientation.