Patent ID: 8222777

Claim:
A single-phase electromagnetic servo-actuator comprising: a rotary actuator configured to move a mobile member along a limited travel including a 2N ferromagnetic pole stator structure, N being equal to 1 or 2, and at least one excitation coil, the stator structure being made of a material with high magnetic permeability and a rotor having a ferromagnetic yoke and a thin magnetized portion of 2N pairs of axially magnetized poles, in alternate directions, and a rotor angular position sensor, the thin magnetized portion being a separate element from the ferromagnetic yoke, wherein the position sensor includes a magnetic field emitter integral with the ferromagnetic yoke and a magnetic field receiver for a magnetic field of the magnetic field emitter stationary relative to the stator structure, wherein the magnetic field receiver is close to the magnetic field emitter and is located in a middle plane of symmetry of at least one of the ferromagnetic stator poles, wherein the magnetic field emitter includes a ring magnet, wherein the magnetic field receiver includes a magnetism-sensitive Hall probe, and wherein the magnetism-sensitive Hall probe is placed between two collection magnetic circuits formed by two ferromagnetic arcs partially enclosing the ring magnet.