Magnetic multi-turn absolute position detection device

A system comprising at least one magnetic device detecting an absolute position and a steering column, the at least one magnetic device detecting the torsion of the steering column, the at least one magnetic device operably detecting the relative angular position of coaxial input and output shafts connected by a torsion bar in order to derive therefrom the torsion torque exerted on the bar, the at least one magnetic device comprising:

• a first rotor magnetic structure comprising a plurality of magnets, and a second stator structure in the vicinity of which at least one magnetosensitive probe is placed;
• a main rotor comprising a main magnet secured to the input shaft effecting a travel greater than 360°, and a driving member of a motion converter;
• at least a first magnetosensitive probe delivering, over a magnetic angle of 360°, a signal proportional to a direction of a magnetic field generated by the main magnet and deriving therefrom a measurement of absolute position of the input shaft;
• a secondary magnet having two magnetic poles and effecting a travel of around 360° under effect of the rotation of the input shaft via the motion converter;
• and
• at least a second magnetosensitive probe delivering, over a magnetic angle of around 360°, a signal proportional to the direction of a magnetic field generated by the secondary magnet and deriving therefrom a measurement of absolute position of the secondary magnet;
• the second probe and the secondary magnet constituting a position sensor;
• the secondary magnet being substantially positioned within a height defined by upper and lower planes of the main rotor;
• and
• the main magnet having multiple pairs of poles, wherein the number of pairs of poles of the main magnet is limited based on the precision of the position sensor;
• the main magnet being substantially concentric with the stator structure;
• at least one of the magnetosensitive probes of the relative angular position detection device and the first and second probes being substantially positioned within the height defined by the upper and lower planes of the main rotor.

A magnetic device for detecting the absolute position of a rotating input shaft, the device comprising:

• a main magnet configured to be secured to the input shaft and having P pairs of poles;
• a first magnetosensitive probe delivering a signal proportional to a direction of a magnetic field generated by the main magnet for deriving a measurement of the position of the input shaft;
• a secondary magnet having two magnetic poles;
• a second magnetosensitive probe delivering a signal proportional to the direction of a magnetic field generated by the secondary magnet for deriving a measurement of the position of the secondary magnet, where P is greater than 1 and is limited based on the precision of a position sensor including the secondary magnet and the second magnetosensitive probe;
• and
• a motion converter including a driving member and a driven member, the driving member being secured to at least one of the input shaft and the main magnet for rotation therewith, the driven member being secured to the secondary magnet and driven by the driving member such that rotation of the input shaft causes rotation of the secondary magnet.