US2749532A - Hydrophone - Google Patents

Description

June 5, 1956 w. T. HARRIS 2,749,532

HYDROPHONE Filed June 4, 1952 FIG. 2.

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BY mf-My 2,749,532 Patented June 5, 1956 HYDROPHONE Wilbur T. Harris, Southbury, Conn., assignor to The Harris Transducer Corporation, Woodbury, Conn., a corporation of Connecticut Application .lune 4, 1952, Serial No. 291,706

8 Claims. (Cl. 340-41) My invention relates to acousto-electric transducers, and in particular to those particularly adaptable to underwater use.

It is an object to provide an improved device of the character indicated.

Itis another object to provide an improved hydrophone construction.

It is a general object to meet the above objects with a structurally simple and rugged construction which may, at the same time, oer superior performance characteristics.

Other objects and various other features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

Fig. 1 is a fragmentary cross-sectional view of a transducer incorporating features of the invention, much of the section being fragmentary and with exaggerated proportions for purposes of emphasis;

Fig. 2 is a fragmentary View in longitudinal section, illustrating an alternative construction;

Fig. 3 is a fragmentary cross-sectional view illustrating a further alternative construction; and

Fig. 4 is a longitudinal sectional View illustrating end constructions for any of the forms of Figs. l, 2, and 3.

Briefly stated, my invention contemplates a transducer construction featuring simplicity and ruggedness, for particular application to underwater use. While the construction is basically adaptable to other forms of radially strictive members, I shall show and describe application to toroidally wound, magnetostrictive devices. Superior performance is achieved with my construction by providing an internal pressure-release medium affording acoustic softness, yet adequate structural rigidity. In one form, a wood dowel provides adequate mechanical support while offering acoustic pressure release. In other forms, similar support is provided by a layer of cork or air-filled rubber or the like, formed as part of a core, as by wrapping such a layer around a metal pipe.

Referring to Fig. 1 of the drawings, my invention is shown in application to a transducer comprising a relatively thin-walled radially-strictive cylindrical member 10, carrying means electrically responsive to radial deformation thereof. The cylinder 1i) happens to be of magnetostrictive material, such as annealed nickel, and the electrically responsive means is a winding 11, toroidally enveloping the cylinder 10. For insulation purposes, the winding 11 may be of enameled wire, or the cylinder 1G may be dipped in an insulating plastic before winding. As a further precaution, edge insulators, as at 12, may be applied over the ends of the cylinder 10, prior to winding.

The cylinder is shown to be magnetized by a permanent bar mag-net 13 inserted in an elongated slot cut in the periphery of the cylinder 10. The magnet 13 is preferably co-extensive with the cylinder 1Q, and is of such circumferential length L as to support an adequate magnetic flux in the nickel of cylinder 10. The relative thicknesses of the bar magnet 13 and of the cylinder 10 are approximately in inverse ratio of the magnetic permeabilities of these members, so that the properties of a uniform toroidally would core are substantially preserved.

In accordance with the invention, I provide pressurerelease means within the cylinder 10 in order to effect principal response to pressure fluctuations externally of the cylinder. The pressure-release means may be a layer of aiI-lled rubber or the like 15, and I have shown layer 15 wrapped around a central mechanical support or core 16, which may be a metal pipe. The device may be made rugged and unit-handling by setting the described parts within a cylindrical boot 17 of rubber-like material and by filling all radial spaces with a solid sound-transmitting material such as plastic, as indicated at 18-19. The plastic at 18-19 should be bubble-free, hard, elastic, and of high strength, and I prefer to perform the casting or potting operation under Vacuum conditions.

In Fig. 2, I show a slightly modified construction and at the same time illustrate the employment of multiple transducer units in a single assembly. In the construction of Fig. 2, the cylindrical members 20-21 may again be magnetostrictive cylinders with permanent-magnet inserts of the Fig. l variety, but I illustrate the employment of circumferentially continuous cylinders 24h-21, The cylinders 2li-21 each have their own toroidal windings 22-23, serially connected or with leads separately brought out, depending upon the desired use. As in the case of Fig.l 1,` the windings 22-23 are laid over edge insulators 24 at the ends of cylinders Ztl- 21. Mechanically rugged, acoustically soft, core support may be provided by a central metal tube 25, which may be common to all transducer elements Ztl- 21, but which I show to be provided separately for each transducer element. The tube or core means 25 may be surrounded with a layer 26 of pressurerelease material, such as cork, impregnated cardboard, or the like, and these parts may be made integral with each cylinder 20-21 by casting with layers of plastic or potting compound 2728. For purposes of assembly, the bores of the core tubes 25 for the various transducer units Ztl-21 may all be supported on a through tie-bolt 29 and placed within a rubber-like cover or boot 30 for final potting, as with' a sound-transmitting plastic 31. When the plastic 31 has set, the tie-bolt 29 may be removed so that the central passage may remain open for accommodation of such wires and other structure members as may be necessary for further assembly.

In Fig. 3, I illustrate an alternative core construction providing a mechanical support that is also acoustically soft. The core in Fig. 3 is merely a wood dowel 35, which, again, may be cast to the wound cylinder 36 by means of a sound-transmitting potting material 37. The entire assembly is shown potted within a rubber boot 38.

In Fig. 4, l illustrate a manner of making end connections for any of the above-described devices. When casting the assembled transducer unit with its core and Within the protecting cover or boot 40, room should be left at both ends for accommodation of a closure bushing, as in the case of bushing 41, which may be of rubber and vulcanized to the jacket of a lead cable 42. Leads 45 from the cable 42 are preferably soldered to the leads from the transducer 43 before bushing 41 is inserted in boot 40. This will mean that, upon inserting the bushing 41 in the unlled end of the cover 41], the leads 45 will be doubled over, due to their excessive length. If the core is a wood dowel, as in Fig. 3, this end of the dowel may be bored out, but in Fig. 4 I show the metal-tube core construction which provides adequate space in which to accommodate the doubled-over lengths of leads 45. After the bushing 41 has been secured, the interior of the core 46 may be filled with plastic, or left unfilled, as desired; but I have shown that rugged insulated connections may be maintained by potting the lead end of the interior, as at 48. The other end of the transducer may be closed by sealing with a plug 47, which may be vulcanized or cemented to the boot 40 and to the potted transducer assembly.

It will be seen that I have described basically simple transducer constructions featuring ruggedness and improved performance. My constructions lend themselves t'o employment under extreme pressure conditions, as at great water depths, because the interior provides strong mechanical support. At the same time the pressure release aiorded by the core construction renders the transducer responsive substantially only to pressure variations originating outside the transducer.

While I have described my invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as dened in the claims which follow.

I claim:

l. In a transducer of the character indicated, an elongated cylindrical radially strictive member, means electrically responsive to radial deformations of said member,

a cylindrical metal supporting core within said member,

a pressure-release layer continuously surrounding said core for substantially the longitudinal extent of said strictive member, and a potting of hard sound-transmitting material intimately encasing and contacting said strictive member and the full outer surface of said pressure-release layer.

2. A transducer according to claim l, in which said pressure-release layer is of cardboard.

3. A transducer according to claim 1, in which said pressure-release layer is of cork.

4A A device according to claim 1, and including a rubber-like boot encasing said potting and in intimate sound-transmitting relation therewith.

5. A hydrophone, comprising an elongated cylinder of magnetostrictive material, a toroidal winding enveloping said cylinder, a pressure-releasing and mechanically supporting core within said wound cylinder, said core being at least longitudinally coextensive with said cylinder, and a solid and hard intimate bond between said core and said cylinder for the longitudinal extent thereof.

6. A hydrophone according to claim 5, in which an elongated permanent magnet is fitted between split longitudinally extending edges of said cylinder, said bond being intimate to the otherwise exposed surfaces of said permanent magnet.

7. In a transducer of the character indicated, an elongated cylindrical radially strictive member, means electrically responsive to radial deformations of said member, a Wood dowel within said cylinder and at least longitudinally coextensive with said cylinder, and a potting of hard sound-transmitting material intimately encasing and contacting said strictive member and the full outer surface of said dowel for at least the longitudinal extent of said strictive member.

8. In a transducer of the character indicated, an elongated cylindrical radially strictive member, means electrically responsive to radial deformations of said member, a pressure-releasing and mechanically supporting core within said cylinder and at least longitudinally coextensive with said cylinder, lead-in means including a sheathed cable with lead-wire connections to said electrically responsive means at one end of said cylinder, and a solid and hard intimate bond between said core and said cylinder for the longitudinal extent thereof, said bond solidly covering said end of said cylinder and encasing said leadwire connection and in sealed relation with said cable sheath.

References Cited in the le of this patent UNITED STATES PATENTS 2,076,330 Wood Apr. 6, 1937 2,431,026 Bundy Nov. 18, 1947 2,438,925 Krantz Apr. 6, 1948 2,472,388 Thuras June 7, 1949 2,521,136 Thuras Sept. 5, 1950 2,613,261 Massa Oct. 7, 1952

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