Distance transducer assembly - has ferromagnetic wire moving w.r.t. coils and supplied with excitation current with different coil field strengths

摘要

The distance transducer produces electrical signals when a given distance is exceeded using a ferromagnetic wire and coils dividing the wire into two or more active zones. A pulse is generated when a magnet passes the coil. It is a simple, robust transducer giving a good signal-to-noise ratio. This makes it suitable for noisy environments such as those found in motor vehicles. The excitation coils (3,4) on the wire (1) are separated by high permeability material (5). The wire is movable in the coil axial direction. A further sensing coil (6) is mounted on one of the excitation coils. One excitation coil generates a higher strength magnetic field than the other. The excitation coil current is generated by a high impedance current source.