Patent GB-628524-A (GB)
Title: Improvements in or relating to the transmission and reception of beams of compressional waves in and near the supersonic range in a liquid medium
IPC: B06B1/04
Filed: 1943-08-19
Abstract: 628,524. Sound transmitting and receiving devices. STEVENS, A. H. (Submarine Signal Co.). Aug. 19, 1943, No. 13561. [A Specification was laid open to inspection under Sect. 91 of the Acts, March 18, 1946.] [Class 40 (iv)] An apparatus for transmitting and receiving compression waves in or near the supersonic range in a liquid medium comprises a radiating plate coupled with a plurality of concentric electrodynamically-driven tubes which form with the associated parts of the plate resonant systems at the frequency of the waves so that the motion of the plate is substantially in phase over the whole radiating surface. The apparatus may be used for such purposes as deaerating liquids, making emulsions, and submarine signalling. The apparatus shown is intended for submarine signalling. The radiating plate 12 is clamped to a ring 11 surrounding the electrodynamic units and formed with a side piece 10 having a flange 1 adapted to be bolted to a depending rotatable tube, not shown. The electromagnetic units comprise a back plate 19' with concentric grooves for a set of directcurrent polarizing coils 20 ... 25. The back of this plate may be flat as in Fig. 1 or provided with heat-radiating fins 81, Fig. 8. The walls of the grooves are extended by rings 28, 33, the latter reaching close to the radiating plate 12 so as to support it against excessive inward deflections. The rings 33 are secured to the rings 28 by radial bolts 39, Fig. 2, and the rings 33 and 28 are together secured to the back plate 19 by bolts 31. The parts of the rings 28 adjacent the rings 33 are recessed to receive polar laminations 42 which are clamped between opposite undercut choulders on the rings 28, 33. The sets of alternating-current coils 45 are wound around the laminated poles 42. A set of aluminium or copper rings 64 are fastened to the radiating plate 12 and extend into the gaps between the laminated poles. The rings 64 may have longitudinal slits 75, Fig. 11, and may be clamped into grooves at the back of the radiating plate 12, as in Fig. 2, or may be clamped at the end of deeper grooves 74, Fig. 11, nearer the centre of mass of the associated elements of the radiating plate 12. A recess may be made at the centre of the back of the radiating plate to reduce the weight of this part as may be required. The plate 13 is surrounded by a comparatively thin neck 14 connecting the plate to a flange 13, which is secured to the ring 11 by bolts 16, the joint being made water-tight by a gasket 18. The back plate 19 is similarly secured to the ring 11. Both the radiating plate 12 and the back,plate 19 are covered by dome-shaped caps 85, 84, the flanges of which are bolted to the flanges 13, 88 respectively. The cap 84 covering the back plate has perforations 90 admitting water to the back plate. The cap 85 covering the radiating plate 12 is imperforate, and the sealed space between it and the radiating plate is filled with a liquid under pressure. The ends 50, Fig. 9, of the coils 45 are connected to insulated tags 51 secured to insulated wires 52 screwed to terminals 57 on the outside of the back plate 19. These terminals are protected by a cover 63, Fig. 6, bolted to the plate 19. Leads 4, 5, Fig. 1, for the coils are taken into ring 11 through a stuffing-box 6 in the supporting side piece 10.