Patent ID: 8766627

Claim:
An angular position sensor, comprising: a rotor core as well as a stator core coaxially around this rotor core, wherein a first air gap is provided between the rotor core and the stator core, which is a uniformly distributed ring air gap, with its size in the radial direction of the rotor core being called width of the first air gap, and the ratio of its width to the diameter of the rotor core being bigger than or equal to 1:5; a second air gap with a hard magnet therein is provided inside the rotor core; and a third air gap with a magnetic flux sensing element therein is provided inside the stator core; wherein the second air gap is designed to be linear along a certain diameter direction of the rotor core, with the size of the second air gap in this diameter direction being called its length and the size of the second air gap in the radial direction of the rotor core its width; and wherein the ratio of the length to the width of the second air gap is bigger than or equal to 5:1 but less than 55:2.