US2364679A - Apparatus for submarine signaling - Google Patents

Description

Dec. 12, 1944. w 2,364,679

PPARATUS FOR SUBMARINE SIGNALING Filed 0013. 8, 1941 Dec IZ, 1944.

2 She ets-Sheet 2 R L WILLIAMS APPARATUS FOR SUBMARINE SIGNALINQ -Filed Oct. 8, 1941 'INVENTO'R Patented n... 12, 1944 APPARATUS FOR SUBMARJNE SIGNALING Robert Longfellow Williams, Newton, Masa, as-

signor to Submarine Signal Company, Boston, Mama, a corporation of Maine Application October 8, 1941, Serial No. 414,122

4Claims.

The present invention relates to underwater sound producing devices. More particularly the present invention relates 'to electromagnetic impact-operated underwater sound transmitters.

The present invention is intended to provide a device for producing an underwater sound or noise of more or less continuous nature but containing a large frequency spectrum while at the same time having a considerable energy content. Such a device has particular use as a sound source for tripping acoustically operated mines,

particularly those of unknown frequency, as well as a sound source to be used for the calibration of binaural direction finding systems.

The invention will best be understood from the following description taken in connection with the accompanying drawings in which Fig. 1 shows a vertical section through my sound producer or oscillator as it will be hereinafter called; Fig. 2 shows a horizontal section taken along the line 2-2 inFig. 1; Fig. 3 shows a plan view of the armature of the oscillator; and Fig. 4 shows a vertical sectlonof a modification of the oscillator.

C Referringto Figs; 1 and 2, a cylindrical steel forging I forms the body of the oscillator and with diaphragm members 2 and 3 having inwardly flanged rims 2a and 3a, respectively, by which the diaphragm tnembers are fastened on either side of the member I by the bolts 4, with the interposition of gaskets 28, 21, thereby pro-' shaped and having integrally formed at its center a striker 9 which is in the form of a solid cylinder terminating below the armature 8 in a hammerhead shaped boss ID. A plan view of the armature is shown in Fi 3. It will be observed that the arms of the cross-shaped armature are slotted as at 30 to reduce eddy currents. Guide pins 3| are provided which are positioned to fit into the corners at the junction of the arms of the cross of the armature 8 and thereby prevent the armature from rotating with respect to the electromagnet field member 5.

The striker 9 is held in position by a hollow cylindrical guide member II which is threaded into a central aperture in the member I by the threads I2 and locked in position by nut 24. The guide member II has a cylindrical recess I3 within which is positioned a spiral spring I4 whose lower end bears against a shoulder I5 on the striker 9. Since the striker 9 and the armature 8 are firmly united in one piece, the spring It will thus urge the boss end III of the striker against the diaphragm 3 and the armature away from the magnet field. The striker is made of such a length that its upper end will then be spaced away from the upper diaphragm 2 by a distance equal to the desired stroke which may vary with the frequency and the noise characteristics desired. The stroke may, for example, be of the order of 0.06 inch.

It will be observed that the tension of the spring It can be regulated by adjusting the guide member I I. The spring tension is preferably adjusted so that the vibrating system formed by the spring It and the mass of the striker and armature will have a resonant frequency at twice the frequency of the alternating current exciting the winding I.

In the operationof the device when the flux I in the field magnet 5 reaches a maximum value, the armature 8 will be attracted toward the field 5, drawing the striker 9 upward against the action of the spring I4 and striking a blow against the diaphragm 2. When the current through the coil I and hence the flux in the magnet 5 falls to zero, the spring It will urge the striker downwards, thereby striking a blow against the diaphragm 8. The action will then be repeated. Since the alternating current will reach a maximum value twice in each cycle, there will be 120 oscillations of the striker 9 per second with cycle excitation of the coil 5, and'for each oscillation both of the diaphragms 2 and 3 will alternately be struck once. In place of alternating current, the magnet may be energized with direct current which is periodically interrupted when the striker makes contact with the upper diaphragm. The diaphragm members 2 and 3 are preferably thickened at the center and may be tuned to any desired frequency preferably in the lower audible range and to a frequency different from the striker freqeuncy. However, greater output at specific frequencies can be obtained by tuning the diaphragms to a frequency which is a multiple of the frequency; of oscillation of the striker. By this arrangement a relatively large amount of sound energy can be radiated into the water.

. center of the bridge 26 there is threaded a stop 22 which can be locked in, any desired position by a locking ring 23. For maximum amplitudthe stop 22 is positioned so that the striker 9 will just make contact with it before the armature ii strikes the magnet field whereby the armature is prevented from sticking to the field member. As in the preceding modification, the resonant frequency of the oscillating striker can be adjusted toequal the frequency of magnet pull, e'. g, twice the frequency of the alternating current supplied to the magnet, by varying the position of member M. In. this modification it may be simpler to introduce the field supply cable ll through a stuffing plug mounted in the cover member it instead of in the manner shown in Figs. 1 and 2.

Having now described my invention, I claim:

1. A submarine signaling device comprising a watertight casing formed of a pair of axially aligned juxtaposed cylindrical memberssecured together and having heavy rim portions and thinner central portions, defining a cavity within said casing, one of said members being adapted to act as' an underwater sound radiating diaphragm adapted by one face to contact the water, the second of said members having a central aperture, electromagnet poles secured to said second member within said cavity and surrounding said aperture, a striker mounted for axial oscillation within said aperture and adapted to strike said diaphragm, an armature carriedby said striker adapted to be attracted by said magnet, spring means tending to urge said striker against said diaphragmand said armature away from said magnet, coil means adapted to be energized by alternatingccurrent for exciting said magnet and means forming a watertight cover over the back side of said second member.

2. A submarine signaling device comprising av Watertight casing formed of a pair of axially alignedjuxtaposed cylindrical members secured together and having heavy rim portions and thinner central portions, defining a cavity within said casing, one of said members being adapted to act as an underwater sound radiating diaphragm adapted by one face to contact the water, 'the second of said members having a central aperture, electromagnet poles secured to said second member within said cavity and surrounding said aperture, a striker mounted for axial oscillation within said aperture and adapted'to strike said diaphragm, an armature carried by said striker adapted to be attracted by said magnet, spring means tending to urge said striker against said diaphragm and said armature away from said magnet, coil means adapted to be energized by alternating current for exciting said magnet, means forming a watertight cover over the back siilebfsaid second member and means formed within said cover for limting thestroke of said striker in its travel away from said diaphragm.

3. A submarine signaling device comprising a cylindrical mass member having a central aperture, a pair of'similar underwater sound radiating diaphragms having inwardly flanged rims, one diaphragm being secured by its flanged'rim to each side of said mass member, thereby forming a hollow watertight casing, an oscillatable striker mounted for axial oscillation in said aperture so as to strike each diaphragm alternately, spring means tensiom'ng saidstriker against one of said diaphragms, alternating current energized electromagnet means mounted on said mass member and an armature carried by said striker adapted to be attracted by said electromagnet for compressing said spring and forcing said striker against the other of said diaphragms.

4. A submarine signaling device comprising a cylindrical mass member having a central aper ture, a pair of similar underwater sound radiating diaphragms having inwardly flanged rims, one diaphragm being secured by its flanged rim toeach side of said mass member, thereby form'- ing a hollow watertight casing, an oscillatable striker mounted for axial oscillation in said aperture so as to strike each diaphragm alternately, spring means tensioning said striker against one of said diaphragms, alternating current energized electromagnet means mounted on said mass member and an armature carried by said striker adapted to be attracted by said electromagnet for compressing said spring and forcing said striker against the other of said diaphragms, the stiffness of said spring being proportioned with regard to the combined mass of said striker and armature to produce'a resonant oscillatory system having a resonant frequency twice that of the magnet-energizing alternating current, said diaphragms being tuned to different multiples of said resonant frequency.

ROBERT LON GFELLOW WILLIAMS.

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