Analysis and Study of Designs of Sensing Elements of Speed Sensors Based on the Wiegand Effect

Speed sensors are used in various products and systems of mechanical engineering, instrument making, flight and rocket and space technology. At the same time, the main requirements for such sensors include a wide range of measured revolutions, from almost zero to several thousand revolutions per minute. Another requirement is a range of operating temperatures, ranging from cryogenic to temperatures of several hundred degrees. In this case, a prerequisite should be a generator method of conversion, in which energy is not consumed from the outside, but it is generated during the operation of the sensor. The principle of operation of the speed sensor is based on the magnetic pulse mode, in which a private hysteresis loop is formed. The generation of such a characteristic is possessed by mechanically and thermally treated wire made of cobalt-iron-vanadium alloy 52K9F of uniform composition. As a result, the wire acquires a composite magnetic structure consisting of an external hard magnetic layer - a shell, a central soft magnetic layer and an intermediate layer. The layers have different properties, due to which the hysteresis loops of the Wiegand wire have a complex shape. A distinctive feature of the loops is the presence of practically vertical sections of magnetization change - discontinuities corresponding to an abrupt change in the magnetization of the material. The large discontinuity on the loops arises due to the so-called "Barkhausen jump", caused by an almost ideal single magnetic domain stretched along the axis of the wire in its core.