Combined position sensor and magnetic motor or bearing

A magnetic sensor and actuator device for applying a magnetic force to a magnetizable body and for sensing the distance between the device and the magnetizable body, said device comprising:

• a magnetizable pole piece projecting toward the magnetizable body and separated therefrom by gaps, said pole piece, gaps, and magnetizable body forming a magnetic circuit, the gaps being the major reluctance of the magnetic circuit;
• first means for generating a relatively large and relatively low frequency time-varying magnetic actuating flux in the magnetic circuit, said flux following a first flux path;
• second means for generating a relatively small and relatively high frequency time-varying magnetic sensing flux in the magnetic circuit, said flux following a second flux path having at least a portion in common with the first flux path;
• and
• detection means for measuring the relatively small, relatively high frequency magnetic flux in the magnetic circuit;
• characterized in that:
• the first and second magnetic flux-generating means comprise a single electrical conductor wound around the pole piece to form a coil;
• the first magnetic flux-generating means further comprises means for generating a relatively low frequency electric current component in the coil, said low frequency electric current component being a drive signal;
• the second magnetic flux-generating means further comprises means for generating a relatively high frequency electric current component in the coil;
• the detection means comprises a high-pass filter for separating the high frequency electric current componet from the low frequency component, said detection means generating a position signal indicating the relative distance between the pole piece and the magnetizable body;
• and
• the device further comprises negative feedback-control means which compare a reference signal to the position signal to generate the driving signal.

A magnetic sensor and actuator devices for applying a magnetic force to a magnetizable body and for sensing the distance between the device and the magnetizable body, said device comprising:

• a magnetizable pole piece projecting toward the magnetizable body and separated therefrom by gaps, said pole piece, gaps, and magnetizable body forming a magnetic circuit, the gaps being the major reluctance of the magnetic circuit;
• first means for generating a relatively large and relatively low frequency time-varying magnetic actuating flux in the magnetic circuit, said flux following a first flux path;
• second means for generating relatively small and relatively high frequency time-varying magnetic sensing flux in the magnetic circuit, said flux following a second flux path having at least a portion in common with the first flux path;
• and
• detection means for measuring the relatively small, relatively high frequency magnetic flux in the magnetic circuit;
• characterized in that the pole piece has three legs and an "E"-shaped cross-section, one of the legs being shorter than the other two, the shorter leg also having an end with a smaller cross-section than the other two legs.