Electromagnetic force-transducer

摘要

An electromagnetic force-transducer comprising a magnetic circuit and an electromagnetic coil kept movable in the static field provided by said magnetic circuit. The electromagnetic coil consists of two coaxial parallel windings wound on a common frame with a distance kept between the both. The magnetic circuit comprises an inner magnetic path and an outer magnetic path with a cylindrical clearance left therebetween. In the upper and the lower part of the clearance there are provided with an upper magnetic gap and a lower magnetic gap, respectively. The magnetic field in the upper gap and that in the lower gap are directed oppositely to each other. The coil frame is kept movable vertically in the cylindrical clearance, positioning one of the two windings in the upper magnetic gap and the other in the lower magnetic gap. The two windings are current-supplied in the directions opposite to each other to produce their respective electromagnetic forces in the same direction. Thus, the magnetic fields produced by the two windings are cancelled by each other, so that the resultant magnetic field by the entire electromagnetic coil does not affect the fields provided at the magnetic gaps by the magnetic circuit.