US2901997A - Sound generator - Google Patents

Description

Sept. 1, 1959 A. H. BROOKS SOUND GENERATOR Filed Sept. 14, 1945 INVENTOR ARTHUR H. BROOKS BY L ATTORNEY 2,901,997 Patented Sept. 1, 1959 ffice SOUND GENERATOR Arthur H. Brooks, Cambridge, Mass., assignor to the United States of America as represented by the Secretary of the Navy Application September 14, 1945, Serial No. 616,388

11 Claims. (Cl. 116-27) This invention relates to a sound generator and is illustrated herein as embodied in an underwater noise-making device adapted for use as a countermeasure against acoustically detonated explosive instruments, or the detection of a ship using the device by another ship having underwater sound locating equipment.

Torpedoes and mines of the so called acoustic type have been designed to utilize the noise of a ships machinery or screw action to actuate their detonating devices. Moreover, owing to the effectiveness of water as a sound conducting medium, the position of one ship from another having underwater sound locating equipment can be determined by the use of either listening or echoranging apparatus which is commonly embodied in such equipment.

Noise making devices have commonly been mounted in ships as countermeasures for detonating mines but such devices have an effective angular scope of limited extent and are usually directed forwardly of the ship only. Furthermore, any ship carrying an operating noisemaker is obviously a better target for the same reason.

In view of the foregoing, it is a principal object of the invention to provide an improved sound generator for confusing the enemy when the ship having the device is under detection, and for affording an effective countermeasure against acoustic torpedoes which may approach the ship from any direction, as well as against a listening or echo ranging operation directed at the ship.

To this end, the invention provides a portable and expendible sound generator adapted to be dropped over the side of a ship from any part thereof and to produce sound or noise of such intensity as to mask that of the ship, and any echo ranging sound impulses, the sound being propagated substantially uniformly in all directions. Accordingly, sound from the generator will detonate any torpedo that would be detonated by the noise of the ship before the torpedo comes dangerously close to the ship. Similarly, any echo ranging impulse reected by the ship will be obscured in the noise from the generator.

As `another feature of the invention, the sound generator has. associated therewith a float, from which the generator is suspended at a desirable level below the surface of the water until the generator becomes exhausted. During the period of its operation, the generator has a substantially fixed position with respect to which a ship under detection can maneuver in any suitable direction to take advantage of the masking or shielding effect of the generator, or the doubt created on the enemy ship as to which source of noise is the real target.

In order tov avoid disclosing the position of the ship using the generator, the float is constructed and arranged slowly to lose its buoyancy so that by the time the sound from the generator ceases the float and generator will have started to sink to the bottom.

With these and other objects and features in view, the invention will now be described with reference to the accompanying drawings whichillustrate a preferred em- 2 bodiment of the invention and will be pointed out in the claims.

Fig. 1 is a side elevation of a sound generator embodying the invention, the float or container for the generator being shown in section.

Fig. 2 is a plan view of the left-hand part of thevgenerator shown in Fig. 1. l

Fig'. 3 is a fragmentary elevation of the time-delay trigger mechanism for actuating the supply valve.

Fig. 3A is a fragmentary sectional view taken along the line 3A-3A of Fig. 3 further illustrating the arrangement of the trigger mechanism for actuating the supply valve, and

Fig. 4 is a view in elevation showing the sound generator suspended in the water by the float.

The illustrated sound generator comprises a oat or containerl which is adapted to house a sound generator unit 12, the float and unit being connected by a coiled line 14 about twenty-five feet in length. The unit 12 comprises a resonator tank 16 having therein a supply of gas under high pressure. `Many kinds of gas can be used Vsatisfactorilyfbut CO2 is especially suitable since it can be liquiied readily,l and `is available in many places. The gas is delivered to an automatic gas operated hammer 18, the striker 20 of which impinges rapidly upon an anvil 22 fixed to the resonator tank. The hammer 18 may be of the conventional hand riveting type which has a striking frequency of about blows per second and which operates at a pressure of approximately 90 pounds per square inch.

When the sound generator is to be used, the unit 12 is removed from the float through an opening in its lower end which is normally closed-by a hinged door 24 when the generator is stowed. The float 10 and unit 12 are then dropped off the ship, whereupon the unit 12 sinks, pulls `the line 14 taut, and causes Vthe float to stand vertically inthe 'water as illustrated in Fig.V 4. This action of the unit 12 and float 10 occurs so rapidly asto trap within the float practically all of the air whichl it contained "when dropped overboard. The upper end of the float 10 is closed except for a small orifice 26 which allows-air to escape from float 10Y slowly enough as to destroy the buoyancy of the float as soon as the gas in the resonator tank 16 has become exhausted.

The resonator tank 16 is composed of a cylindrical body having'hemispherical ends, the wall thickness of which is great enough to withstand pressure in the neighborhood of 2,000 psi. The illustrated resonator tank has windings of piano wire 28 'soldered thereto which are intended to avoid any shrapnel effect which might result from the tanks bursting if hit by a projectile.- Fixed to the discharge end of the tank 16 is a bracket 30 on which the hammer 18 is mounted close beside and parallel to the tank.

Gas is supplied from the tank 16 to the hammer 18 through well-known commercially manufactured connections comprising a supply valve 32 which is xed on the discharge end of the tank 16, ya reducing valve 34, which is to be adjusted in accordance with the requirements of the particular hammer used, and pipes 36 and 38 which connect the reducing valve with the supply valve 32 and the hammer 18, respectively.

The stem 40 of the supply valve32 is normally urged outwardly into its closed position by the internal mechanism of the valve. ln order to permit the unit 12 and float-10 to become stabilized in the water as shown in Fig. 4, before the operation of the hammer 18 has started, al time delay device is provided for actuating the supply valve, This device comprises a trigger 42 which is pivoted on a stud 44 and is spring-loaded by a spring 46 having a suicient force stored therein to operate the valve stem 40 when the trigger is released. The stud 44 is mounted on an `arm 48 which is fixed to the bracket 30, the arm having a flange 50 which provides an abutment for the upper end of the spring 46.

The trigger is normally heldcloseto, but-.out of engagement with, the valve stem 40, by a cord 52 which is looped around the trigger and is secured to the flange 50. The cord is broken to release the, trigger byA a blasting cap 54 mounted on the arm 48 andconneeted `tooneend of a fuse 5.6.- As shown in Fig. 3A the cord 52 isdisposed in close proximity with blasting can 54 whereby upon detonation of the c ap, ruptureofjthe cord is insured. The fuse is. securedlto the flangellr-by. a cord 5.8 and has a lanyard 60 which whenpulled operates a standard blasting fuse igniter to ignite .the fuse 56. Thus, after ashort interval; (about 30 seconds),- beginning with. the pulling7 of the lanyard, the fuse setsolff the cap 54 thereby initiating the operation of th'e hammer- 18.

The anvil Z2- is soldered to the mid-"portionV of-the resonator tank 16at the side thereof. Various tests made with the anvil and hammer in different positions'with respect to the tank, indicate the superiority-of-the illustrated arrangement from the standpoints of both volume and directionalityv of the sound produced. As a result ofI investigating the directionality pattern of the illustrated sound generator, it hasbeen found to provide a substantially constant intensity of sound inf-alldirections with regard to a plane including the longitudinal axis of the tank as well as a plane perpendicular to the axis of the tank.

The upper end'of the float is` tightly closed except for the restricted orifice 26. This orice is made to close limits by soldering a tungsten wire, .010" in diameter, into -a larger hole in the tank near its upper end, and then withdrawing the wire to which the solder does not adhere. Near the lower end of the float and fixed thereto is a clip 62 to which the line 14 is attached, the other end of the line being tied around the discharge end of the resonator tank 16.

The door 24 closely ts the lower end of the float-and is normally held closed by aspring hinge 64.

Exhaust holesy 59 in the hammer may be sealed watertight by a piece of tape whichis broken by the exhaust gases from the hammer as soon as it begins to operate. A` similar temporary seal may be made between the striker 20 and the body of the hammer.

Briefly to summarize the operation of the illustrated sound Igenerator, when occasion for its use arises, the unit 12 is removed from the oat 16 and after the lanyard 6il-is pulled to ignite the fuseS6, the unit and float are dropped o'ver the side of the ship. The unit lzquickly sinks making the line 14 tautand hence righting the oat so -that it standsvertically in the water as indicated'in Fig. 4. At this time the unit is suspended about 25 feet below the surface of the water and begins to operate as soon as the fuse` 56 sets off the cap 54.

Owing to the weight of the unit 12 the air which is trapped in the float is compressed somewhat and slowly discharges through the orifice '26. Consequently, the water rises slowly in the float throughout the period of operation ofthe hammer. Eventually, when the gas supply in the tank 16 is exhausted, the-buoyancy of the iloat is diminished to the point where-it will no longer support the unit 12 andthen the float and unit together sink to the bottom.

What is claimed is:

l. A soundv generator comprising a resonator tank adapted to hold compressed gas, an anvil'ixed to said tank, a gasoperated hammerhaving a highstriking frequencyy arranged to impinge on said-anvil connections between said container and-hammer for' supplying gas to the latter, saidconnections comprising a valve and a pressure reducing valve, a spring loaded trigger for opening said supply valve, means fory holding said trigger in an inoperative position awaytfrom said valve andexplo- 4g, sive means for releasing said last-mentioned means whereby said supply valve is opened by said trigger.

2. A sound generator comprising a resonator tank adapted to hold compressed gas, an anvil fixed to said tank, a gas-operated hammer having a high striking frequency mounted on said tank and arranged to impinge on said anvil, connections between said container and hammer comprising a supply valve and a pressure reducing valve, a spring operated trigger for operating said supply valve, means for releasably holding said trigger away from said valve, said means comprising a fuse and cap constructed and arranged to free said trigger at the end of a short interval after said fuse is ignited.

3. A sound generator comprising a resonator tank adapted to hold compressed gas, a gas operated hammer having a high striking frequency secured to said tank, an anvil fixed to said tank and arranged to be successively engaged by said hammer, connecting meansbetween said tank and said'hammer for supplying gas to the latter, a trigger mechanism operable to permit ilow of gas from said tank to said hammer, and explosive means for releasing said trigger mechanism.

4. A sound generator comprising a resonator tank adapted to hold compressed gas, an anvil mounted on said tank at the mid-portion thereof, a gas operated hammer having a high striking frequency arranged to successively impinge upon said anvil, connecting means including a supply valve between said tank and said hammer for supplying gas to the latter, a spring loaded trigger for opening said supply valve, means for holding said trigger in an inoperative position away from said valve, and explosive means for releasing said last mentioned means whereby said supply valve is opened by said trigger.

5. A sound generator comprising a resonator tank adapted to hold compressed gas, an anvil mounted on said tank at the mid-portion of said'tank, a gas-operated hammer having a .high striking frequency arranged to impinge on said anvil, connecting means including a shut-off valve and a pressure-reducing valve between said tank vand said hammer for supplying gas to the latter at the operating pressure of said hammer, a spring loaded trigger for opening said shut-off valve, means holding said trigger in its inoperative position, and explosive means for releasing said last-mentioned means after a predetermined interval from an initial time whereby said shut-off valve is opened by said trigger.

6. A sound generator comprising, in combination, a cylindrical tank adapted to `hold `gas under pressure, an anvil secured to said tank, a gas-operated hammer having a high striking frequency secured to said tank and arranged successively to engage said anvil, and means connecting saidtank with saidhannner for supplying gas to said hammer at its operating pressure.

7. A sound generator comprising, in combination, a tank adapted to hold a compressed gas, an anvil secured to the wall of said tank substantially equidistant the ends thereof, a ygas-operated hammer having a high striking frequency secured to said tank in substantially parallel relationship with said tank and arranged successively to impinge on said anvil, and gas-conducting means connecting said tank with said hammer for supplying gas to said hammer at its operating pressure.

8. A sound generator comprising, in combination, a cylindrical tank adapted to hold gas under pressure, an anvil secured to said tank at the mid-portion thereof, a gas-operated hammer having a high striking frequency secured to said tank and arranged successively to impinge on said anvil, said tank functioning as a resonator of sound'waves produced by the striking of said anvil by said hammer, gas-conducting means including a shut-off valve connecting said tank with said hammer, and means for opening said shut-off valve after a predetermined interval from an initial time.

9. Apparatus in accordance with claim 8 wherein said last-mentioned means comprises a'sprng loaded trigger normally held away from said shut-0E valve, and explosive means for releasing said trigger to open said shut-off valve.

10. Apparatus in accordance with claim 8 wherein said last-mentioned means comprises a spring loaded 5 trigger normally held away from said shut-oli valve by a cord, and a fused detonating cap positioned adjacent said cord for rupturing said cord and releasing said trigger to open said shut-off valve.

11. A sound generator comprising, a resonator tank 10 ing means including a shut-off valve and a pressure re- 15 ducing "valve connecting said tank with said hammer, a spring-loaded trigger for opening said shut-0E val-ve, a cord holding said trigger in an inoperative position away from said shut-o valve, and a detonating cap having a fuse attached thereto mounted adjacent said cord for rupturing said cord at the end of a short interval after said fuse is ignited thereby permitting the ow of gas ffrom said tank to said hammer.

References Cited in the le of this patent UNITED STATES PATENTS 1,292,439 Dalen Jan. 28, 1919 1,496,746 Slichter June 3, 1924 1,611,740 Haknemann Dec. 21, 1926 2,397,844 Dewhurst Apr. 2, 1946

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