GB422259A - Vibratory structure for sound transmitters or receivers, particularly for submarine purposes - Google Patents

Abstract

422,259. Sound receiving and transmitting devices. ATLAS-WERKE AKT.-GES., 16, Stephanikirchenweide, Bremen, Germany. April 6, 1934, No. 10510. Convention date, April 6, 1933. [Class 40 (iv)] Relates to magnetostrictive sound transmitters or receivers, more particularly for submarine purposes, in which the magnetic lines of force flow in a magnetically closed circuit of magnetic material and consists of an arrangement in which the conversion of electrical energy into mechanical energy and vice versa takes place substantially only at those points of the vibratory member where the greatest elongation per unit of length occurs at resonance. Fig. 1 shows a construction in which a bar-shaped vibratory member 4 composed of individual wires, sheets or tubes of magnetostrictive material is rigidly secured at one end to a large mass 5. When the bar 4 is vibrated longitudinally at its fundamental frequency, the amplitude of movement at the point at which the bar is secured to the mass 5 is practically zero while at the free end of the bar it has a maximum value. Conversely, the elongation per unit length at the free end is zero and reaches its maximum value in the neighbourhood of the point at which the bar is secured to the mass 5. The coil winding 6 is therefore arranged on that part of the bar which borders on the mass 5. Yokes 7 of laminated sheet iron surrounded by coils 8 are also provided as shown and complete a magnetic circuit through the mass 5, which is also of laminated sheet iron, and the bar 4. According to a modification of this construction (Fig. 2, not shown), the bar-shaped member is vibrated at an overtone and the yokes carrying the magnetic alternating flux are arranged at a point about one quarter of a wave length from the free end of the bar. Fig. 3 shows a construction employing two bar-shaped magnetostrictive members 12 united at their ends by plates 13, the coils 14 being arranged around the central zones of the bars and the magnetic flux limited substantially to these central zones by magnetic yokes 15. Fig. 4 shows a further modification in which the vibratory body consists of a number of sheets 16 having end masses 19, 20 connected by bridges 17 surrounded by the coils 18, the magnetic flux being concentrated substantially in the bridges. According to a modification of this arrangement, Fig. 5, a magnetic yoke 21 carrying the coil 23 is arranged in a recess in the sheets 22, the magnetic flux being again concentrated substantially in the bridges 24.