Magnetostrictive flexural vibrator engine knock detector - is folded to form opposite polarity regions and carries coil

摘要

A magnetostrictive knock detector for combustion engines has a flexural oscillator clamped at one end to a part (3) of the engine transferring the knock vibrations to it and perpendicular to the direction of vibration of that part. The magnetostrictive material used is relatively easy to process and insensitive to shocks. The magnetostrictive material (1) has one or more coils (7) wound around it and forms the flexural vibrator. The coil (7) is arranged near the point at which the vibrating sensor is clamped to the engine part (3). The flexural vibrator can have two regions of opposite polarity in its plane of oscillation. These are formed by folding a magnetostrictive plate so as to leave a negligible gap at the point of clamping. The sensor may be premagnetised using an additional coil.