Foucault current tachometer for low speeds - has surface of rotational symmetry with star shaped metallisations facing oscillator coil

摘要

The tachometer contains a magnet casing and a speed sensor allowing, in particular, a zero speed or a low speed to give a signal. A metallised surface (3) is situated symmetrical in relation to the rotation axis (2) and is deposited on the front face of the plastics magnet casing. The metallised surface (3) has the shape of teeth, a star or sectors. The coil (4) of a metal sensing oscillator is placed in front of the front face in the active zone of the metallised surface (3). The sensor can be fitted inside a small space and easily added to a conventional tachometer and has a long life.