US3267421A

US3267421A - Underwater sound source

Info

Publication number: US3267421A
Application number: US185648A
Authority: US
Inventors: Leonard L Robinson; John A Trevett
Original assignee: Textron Electronics Inc
Current assignee: Textron Electronics Inc
Priority date: 1962-04-06
Filing date: 1962-04-06
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

Aug. 16, 1966 L. L. ROBINSON ET AL 7,

UNDERWATER SOUND SOURCE Filed April 6, 1962 6 Sheets-Sheet l INVENTORS LEONARD L. ROBINSON JOHN A. TREVETT BY K ng/1W4 %M ATTORNEYS.

L. L. ROBINSON ET AL UNDERWATER SOUND souncn Aug. 16, 1966 3,267,421

filod April 6, 1 962 6 Sheets-Sheet 2 mvzmoas ,J| Lemma L. mewsow JOHN A. TREVEYT av v %.LM ZMMM ATTQRNEXS.

Aug. 16, 1966 L. 1.. ROBINSON ETAL 3,267,421

UNDERWATER SOUND SOURCE 6 Sheets-Sheet 3 Filed April 6, 1962 INVENTORS AFZD L. ROBINSON A. TREVETT g- 1966 L. L. ROBINSON ET AL 3,267,421

UNDERWATER SOUND SOURCE 6 Sheets-Sheet 4 Filed April 6, 1962 NW \IP ATTORNEYS.

Aug. 16, 1966 1.. L. ROBINSON ET AL 3,267,421

UNDERWATER SOUND SOURCE 6 Sheets-Sheet 5 Filed April 6, 1962 KUvm ATTORNEYS.

Aug. 16, 1966 L. L. ROBINSON ET AL 3,267,421

UNDERWATER SOUND SOURCE Filed April 6, 1962 6 Sheets-Sheet e INVENTORS LEONARD L.ROBINSON JOHN A. TREVETT ATTORNEYS.

United States Patent 3,267,421 UNDERWATER SOUND SOURCE Leonard L. Robinson, Old Saybrook, and John A. Trevett, Old Lyme, Conn., assignors to Textron Electronics, Inc., Providence, R.I., a corporation of Delaware Filed Apr. 6, 1962, Ser. No. 185,648 6 Claims. (Cl. 340-12) The present invention relates to underwater sound sources or generators.

Underwater sound sources can be divided into two basic categories in accordance with the nature of the source of power, i.e., electroacoustic and hydroacoustic. With both types, an electrical control signal is converted into an acoustic output. Typical of the electroacoustic devices are those making use of the electromagnetic and piezoelectric effects. In the hydroacoustic device the electric signal is used to control a fluid valve which modulates the flow of hydraulic fluid to actuate an acoustic radiator. It is with the hydroacoustic device that the present invention is concerned.

As with all acoustic sources, efficiency in power conversion with high output power capability over a wide frequency range is a design objective. At the same time, excessive weight and size is to be avoided.

The hydroacoustic device is capable of developing high power output at extremely low frequencies, say below 600 c.p.s. One such devi-ce is based upon the principle of simultaneously driving a pair of opposed radiator pistons in opposite directions relative to a stationary housing in which they are sealed to alter the instantaneous volume of the housing, thereby creating sound pressure in the surrounding medium.

For extremely large power output it becomes expedient to employ individual control valves with hydraulic amplification for each actuator element and to drive the plurality of valves in parallel. However, for a low power device the flow requirements are reduced and there no longer is a need for the greater flow capacity of multiple valving. Thus, strictly from a consideration of the flow requirements it would seem possible to use only a single valve to control a plurality of actuators.

Single valve control of multiple actuators implicitly requires that the hydraulic circuits of the actuators be freely interconnected. Since the actuator elements (and thereby the radiator pistons) must move in unison for proper acoustic operation this poses a serious problem.

For example, consider two pistons in a common cylinder with fluid under pressure being admitted between them. The piston which is subjected to the smaller retarding force including load reaction, friction and so forth, will move to its end stop before the other piston moves at all. This type of out-of-phase operation can not be tolerated for faithful non-distorted acoustic reproduction.

The discovery of a way to overcome this seemingly incompatible situation forms the basis of the present invention. A sound source was constructed both with a symmetrical hydraulic system between the actuator elements associated with the respective radiator pistons and with a strong spring acting to bias each radiator piston to an intermediate position. Through actual field tests it was discovered that the radiators did move in unison sufliciently so that the distortion remained at an acceptable low level.

Therefore, in accordance with the present invention there is provided an underwater sound source comprising a fluid tight housing having rigid wall portions including oppositely directed sound-radiating pistons, at least two hydraulic actuator means within the housing coupled mechanically one to each of the pistons for imparting reciprocatory motion thereto, means for obtaining hydraulic power, valving mechanism within the housing,

"ice

duct means freely inter-coupling the actuator means in parallel and to the means for obtaining hydraulic power through the valving mechanism for operation under the control of the valving mechanism, the duct means between the valving mechanism and the actuator means being dimensioned to provide for hydraulic symmetry between the actuator means coupled respectively to one and the other of said pistons, spring means coupling each of the pistons to stationary portions of the housing for biasing the pistons toward an intermediate position, and means for controlling the valving mechanism so as to cause reciprocation of the pistons substantially in unison alternately outwardly and inwardly relative to the interior of the housing thereby varying the instantaneous volume of the housing.

A better understanding of the invention will be had after reading the following detailed description with reference to the appended drawings in which:

FIG. 1 shows the essential organization and relationship of parts of an underwater sound source embodying the present invention, the fluid tight housing being shown somewhat simplified and in longitudinal section with the exception of the pistons of which only a portion is broken away, the piston driving mechanism which includes a valve body, the valving mechanism, the controlling means therefor, the duct means, and the actuator means being represented in simplified schematic form;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1 and showing the nature of the radiator piston;

FIG. 3 is a top plan view of an actual embodiment of gileGpilston driving mechanism shown schematically in FIG. 4 is a bottom plan view of the driving mechanism shown in FIG. 3;

FIG. 5 is an elevational view of the left side of the driving mechanism shown in FIG. 3;

FIG. 6 is an elevational view of the right side of the driving mechanism shown in FIG. 3;

FIG. 7 is an elevational view of the front of the driving mechanism shown in FIG. 3;

FIG. 8 is an irregular sectional view to a slightly enlarged scale taken generally along line 8-8 .of FIG. 3 with certain parts broken away for clearer representation;

FIG. 9 is a horizontal sectional view on the same scale as FIG. 8 taken along line 9-9 of FIG. 5;

FIG. 10 is a fragmentary sectional view taken along line 10-10 of FIG. 4;

FIG. 11 is a fragmentary sectional view taken along line 11-11 of FIG. 4; and

FIG. 12 is a fragmentary sectional view taken along line 12-12 of FIG. 4.

Reference should now be had to FIGS. 1 and 2. In this illustrative example it is assumed that the source of hydraulic power as well as the source of control signals are external to the underwater sound source. The sound source is shown as consisting of .a cylindrical fluid tight metal housing 10 having rigid wall portions including the oppositely directed sound radiating pistons 11 and 12. The latter are characterized by a ribbed construction to ensure lightness in weight with maximum rigidity.

A thick (e.g. /2") sheet of rubber or other strong waterproof elastic material covers each piston 11 and 12 at 13 and 14, respectively, and extends beyond the pistons to overlap the stationary portion of the housing. The

sheets

13 and 14 are bonded as by an epoxy cement to the outer surface of the corresponding piston and are fastened as by screws 15 to the housing 10. The junction with the housing must be watertight.

The pistons 11 and 12 are biased by the restraining action of the

elastic sheets

13 and 14 so as to tend to assume the position seen in FIG. 2 in the corresponding openings 16 and 17 in the housing 10.

The actual mechanism for driving the pistons 11 and 12, due to its complexity, has been reduced to schematic form in FIG. 1 for convenience in explaining its construction, operation, and basic principles. While the ensuing discussion, therefore, will be confined to FIGS. 1 and 2, reference should be had to FIGS. 3 to 12 for the actual details of construction. The same reference numerals appearing in FIGS. 1 and 2 are used throughout FIGS. 3 to 12 to designate corresponding parts. Since FIGS. 1 and 2 represent only a simplified schematic, what appears as a single element therein may involve a combination of several parts in the actual embodiment. In such case the several parts since they serve the same purpose or function are designated by the same basic reference numeral appearing in FIGS. 1 and 2, but are distinguished by small letters of the alphabet. For example, in FIG. 1 a single passage or duct 53 connects a port 45 in a cylinder 23 to a passage 57. In FIGS. 3 to 12 (see particularly FIG. 12) the port 45 communicates with passage 53a which connects with passage 53b which in turn, joins passage 57.

Where reference characters are shown in parenthesis they represent eclipsed or hidden structure of identical construction.

The passages in the valve body to be described were introduced by drilling or boring operations. These operations were carried out in known manner from a face or other accessible surface of the body. Unwanted portions of the bores at the entrances to the body were then suitably plugged. In order to facilitate reading of the drawings and to avoid repetitious description the small letter x has been used throughout FIGS. 3 to 12 after a reference numeral to indicate the point of entry of the boring tool and the plug for a given passage designated by the same numeral without the x. For example, 53ax is the plugged entrance for drilled passage 53a (see FIG. 12).

Now, returning to FIGS. 1 and 2, the mechanism for driving the pistons 11 and 12 is housed in a valve body 18. The piston 11 is coupled by

rods

19 and 20 to two hydraulic actuator means or elements within the housing in the form of

identical rams

21 and 22 riding in identical

corresponding cylinders

23 and 24 in body 18.

Identical rams 25 and 26 riding in

identical cylinders

27 and 28 are coupled by

rods

29 and 30 to piston 12. It should be observed that with the pistons in the neutral position with minimum stress of the elastic sheets the

rams

21, 22, 25 and 26 are all located at the center or intermediate position of the respective cylinders. The actuator elements, each consisting of a ram and cylinder, are of the rectilinear motion type and impart reciprocatory motion to the radiators.

The present device requires a closed hydraulic system having a pressure line brought in through the connection 31 and a return line coupled through connection 32. The pressure line is shown symbolically entering the valve body 18 at port 33 while the return line is shown symbolically at port 34.

Valving mechanism in the form of a spool valve 35 having a spool 36 riding in a multiported valve housing 37 is located within the valve body 18 and, consequently, within the housing 10.

The spool valve housing 37 has means in the form of

ports

38, 39 and 40 for coupling the valve via passages or ducts in the valve body 18 to the pressure and return

ports

33 and 34. For reasons to be explained below the spool 36 has a neutral closed position (see FIG. 1) and two operative open positions. The valve spool is constructed with lands 41 and 42 to occlude a first valve port 43 and a second valve port 44 simultaneously in the neutral position, as shown. When the spool 36 is displaced downwardly as viewed in FIG. 1 the port 43 is brought into communication with the port 39 coupled to the return port 34 while the port 44 is opened to the pressure port 33 by way of valve port 38. Alternatively,

when the spool 36 moves upwardly from the neutral position the port 43 is coupled to the pressure port 33 and the port 44 is coupled to the return port 34.

A symmetrical system of ducts in the form of fluid passages in the body 18 are provided for coupling the actuator elements to the valve mechanism. Considering the cylinder 23 it is provided at opposite ends with fluid ports 45 and 46. If fluid under pressure is introduced through port 45 to the cylinder it will urge ram 21 toward the right as viewed in FIG. 1. This will urge the piston 11 outwardly of the housing 10 thereby straining the elastic sheet 13 which, in addition to its function of hydraulically sealing the housing, functions as a spring tending to return the piston 11 toward the left to its neutral position.

If the fluid is now permitted to leave cylinder 23 through port 45 while fluid under pressure is supplied to port 46 the ram 21 and piston 11 will move to the left until the supply of pressure fluid stops. Assuming suflicient flow the piston 11 will be drawn inwardly again straining elastic sheet 13. For convenience, we can refer to movement of ram 21 when pressure is supplied through port 45 as movement in a first mode and when pressure is supplied through port 46 as movement in a second mode. Each of the

other rams

22, 25 and 26 can be said to have similar modes of operation. The corresponding cylinders each have a port associated with each mode of operation. Thus, cylinder 24 has

ports

47 and 48, cylinder 27 has ports 49 and 50 and cylinder 28 has

ports

51 and 52.

Four passages, 53, 54, 55 and 56, all of equal length and diameter, join the

respective ports

45 and 47 to a passage 57 and ports 49 and 51 to a passage 58. Again, the

passages

57 and 58 should be of equal length and diameter although the diameter may be larger than that of

passages

53, 54 55 and 56. The

passages

57 and 58 merge in a passage 59 which connects with valve port 43.

In similar manner the

ports

46, 48, 50 and 52 are coupled through four

passages

60, 61, 62 and 63 to

passages

64 and 65 which merge into passage 66 coupled to valve port 44. The

passages

60, 61, 62 and 63 should all be equal in length and diameter.

Passages

64 and 65, likewise, are made equal in length and diameter. Immediately, it should be evident that perfect hydraulic symmetry exists between the actuator means coupled to piston 11 on the one hand and the actuator means coupled to piston 12 on the other hand. Furthermore, in the actual structure shown in FIGS. 3 to 12 the lengths of the various passages were chosen such that every port in the

cylinders

23, 24, 27 and 28 was the same total distance from the corresponding

valve port

43 or 44. For example, the total length of

passages

53, 57, and 59 ,was made equal to the total length of

passages

62, 65 and 66.

The important factor is to construct the passages or ducts which couple the valve mechanism to the actuator elements so as to obtain substantially identical fluid transfer characteristics between the spool valve and each of the actuator elements. This means that the pressure drops, phase lags, and flow rates shall be substantially identical in the hydraulic supply to each actuator element. It should also be understood that for eflicient operation the pressure drop should be maintained at a minimum. This can be achieved by enlarging the diameters of the fluid passages. However, enlarging the size of the passages increases the compliance of the fluid which introduces serious phase distortion. It is necessary to arrive at an arbitrary compromise. A pressure drop of about 50 p.s.i. proved satisfactory in the structure which was field tested.

An electrodynamic structure including a D.C. energized field 67 and a voice or signal coil 68 actuates or controls the spool 36 through an armature 69 acting against the reaction of a resilient pad or cushion 70. The armature 69 is resiliently supported in a neutral posit on by

resilient supports

71 and 72. It will be understood that with no signal on the coil 68 the

supports

71 and 72 maintain downward pressure on the spool 36 to keep pad 70 under compression. Thus, the pad is capable of urging the spool in the upward direction when the control signal is such as to move the armature 69 in that direction.

A drain system 73 is provided for returning all hydraulic fluid that should leak past the various seals to a return line 74. Finally, since the entire device is intended to operate well below the surface of a body of water,

connections

75 and 76 are provided for supplying and exhausting air under pressure to and from the interior of housing 10. The internal pressure is maintained preferably fractionally higher than the external hydraulic head in order to ensure air leakage as opposed to water ingress in the event of a leak developing. At the same time the system is balanced dynamically so that power is required only for imparting acoustic energy to the surrounding medium.

Terminal 77 is provided for the various electrical connections required to energize and control the electrodynamic structure.

It has been mentioned that with zero signal on coil 68, the cushion 70 is under compression. As shown in the drawings the electrodynamic structure is constructed as a unit and installed in valve body 18 so that armature 69 rests on the end of the valve spool 36. Initial adjustment of the position of spool 36 and the degree of compression of cushion 70 is obtained by positioning the electrodynamic structure with the threaded

members

78, 79 and 80. (See FIGS. 3 and 8.) Member 78 is threaded into the top of the electrodynamic structure for raising same While members 79 and 80 are threaded into the top cover 81 joined to the valve body for imparting downward movement. The structure is locked in final position by

set screws

82, 83 and 84.

By comparing FIGS. 3-12 with FIG. 1 it is possible to follow and understand all of the details of construction and operation, bearing in mind that the same reference numerals are used throughout to designate the same or equivalent part.

Above there has been described what is presently considered the preferred structure for embodying the invention. Nevertheless, numerous changes will appear to those skilled in the art and it is to be understood that these are contemplated herein to the extent that they do not depart from the true spirit of the invention as defined in the appended claims.

What is claimed is:

1. An underwater sound source comprising:

a fluid tight housing having rigid wall portions including oppositely directed sound-radiating pistons,

at least two hydraulic actuator means Within said housing coupled mechanically one to each of said pistons for imparting reciprocatory motion thereto, means for obtaining hydraulic power, a central valving mechanism within said housing, duct means freely inter-coupling said actuator means in parallel, said duct means additionally coupling said actuator means to said means for obtaining hydraulic power through said central valving mechanism for operating the actuator means under the control of said central valving mechanism, the duct means between said central valving mechanism and said actuator means being dimensioned to provide for hydraulic symmetry between the actuator means coupled respectively to one and the other of said pistons,

spring means coupling each of said pistons to stationary portions of said housing for biasing said pistons toward an intermediate position,

and means for controlling said central valving mechanism so as to cause reciprocation of said pistons substantially in unison alternately outwardly and inwardly relative to the interior of the housing thereby varying the instantaneous volume of said housing.

2. An underwater sound source according to claim 1,

wherein said actuator means are each coupled by said duct means in a closed hydraulic loop to said means for obtaining hydraulic power, with said central valving mechanism interposed at least between the pressure side of said means for obtaining hydraulic power and said actuator means.

3. An underwater sound source according to claim 2,

wherein said central valving mechanism is interposed between said actuator means and both the pressure and return sides of said means for obtaining hydraulic power.

4. An underwater sound source comprising:

a first group of one or more hydraulic actuator means within said housing coupled mechanically to one of said pistons for imparting reciprocatory motion thereto,

a second group of one or more hydraulic actuator means within said housing coupled mechanically to the other of said pistons for imparting reciprocatory motion thereto,

means for obtaining hydraulic power,

a unitary valve assembly within said housing coupling said means for obtaining hydraulic power through a network of fluid passages to said two groups of actuator means in parallel and free inter-communication for operating the latter under the control of the valve assembly, the fluid passages being dimensioned to provide for hydraulic symmetry between the actuator means of said first and second groups,

and means for controlling said valve assembly so as to cause reciprocation of said pistons substantially in unison alternately outwardly and inwardly relative to the interior of the housing thereby varying the instantaneous volume of said housing.

5. An underwater sound source comprising:

at least two rectilinear motion hydraulic actuator elements within said housing coupled mechanically one to each of said pistons for imparting rectilinear motion thereto, said elements each having a first mode of operation and an hydraulic fluid port associated with such mode,

a pressure and a return port for supplying hydraulic power,

a multi-ported spool valve within said housing constructed selectably to occlude or couple a first valve port alternatively with a second or third valve port,

first duct means for coupling said second and third valve ports respectively with said pressure and return ports,

second duct means inter-coupling between themselves and with said first valve port all of the fluid ports of said actuator elements which are associated with said first mode of operation, said second duct means being dimensioned to provide substantially identical fluid transfer characteristics between said spool valve and each of the actuator elements,

and means for controlling said spool valve so as to cause reciprocation of said pistons substantially in unison alternately outwardly and inwardly relative to the interior of the housing thereby varying the instantaneous volume of said housing.

6. An underwater sound source comprising:

at least two rectilinear motion hydraulic actuator elernents within said housing coupled mechanically one to each of said pistons for imparting rectilinear motion thereto, said elements each having two modes of operation and one hydraulic fluid port associated with each mode,

pressure and a return port for supplying hydraulic power,

multi-ported spool valve within said housing including means for coupling it to said pressure and return ports and having a neutral closed position and two operative open positions, said valve being constructed to occlude a first and a second valve port simultaneously in said neutral position and to couple said first and second valve ports in said operative positions alternatively with said pressure and return or return and pressure ports respectively,

first duct means inter-coupling between themselves and with said first valve port all of the fluid ports of said actuator elements which are associated with a first of said two modes of operation,

second duct means inter-coupling between themselves and with said second valve port all of the fluid ports of said actuator elements which are associated with the second of said two modes of operation,

said first and second duct means being dimensioned to provide substantially identical fiuid transfer characteristics between said spool valve and each of the actuator elements,

References Cited by the Examiner UNITED STATES PATENTS 2,172,066 9/1939 Logsdon 116l37 3,056,104 9/1962 De Kanski et al 340--5 3,059,663 10/1962 Whitenack 137-623 3,143,999 8/1964 Bouyoucos 340-8 X CHESTER L. JUSTUS, Primary Examiner.

LOUIS J. CAPOZI, LEWIS H. MYERS, Examiners.

G. M. FISHER, Assistant Examiner.

Claims

1. AN UNDERWATER SOUND SOURCE COMPRISING: A FLUID TIGHT HOUSING HAVING RIGID WALL PORTIONS INCLUDING OPPOSITELY DIRECTED SOUND-RADIATING PISTONS, AT LEAST TWO HYDRAULIC ACTUATOR MEANS WITHIN SAID HOUSING COUPLED MECHANICALLY ONE TO EACH OF SAID PISTONS FOR IMPARTING RECIPROCATORY MOTIONS THERETO, MEANS FOR OBTAINING HYDRAULIC POWER, A CENTRAL VALVING MECHANISM WITHIN SAID HOUSING, DUCT MEANS FREELY INTER-COUPLING SAID ACTUATOR MEANS IN PARALLEL, SAID DUCT MEANS ADDITIONALLY COUPLING SAID ACTUATOR MEANS TO SAID MEANS FOR OBTAINING HYDRAULIC POWER THROUGH SAID CENTRAL VALVING MECHANISM FOR OPERATING THE ACTUATOR MEANS UNDER THE CONTROL OF SAID CENTRAL VALVING MECHANISM, THE DUCT MEANS BETWEEN SAID CENTRAL VALVING MECHANISM AND SAID ACTUATOR MEANS BEING DIMENSIONED TO PROVIDE FOR HYDRAULIC SYMMETRY BETWEEN THE ACTUATOR MEANS COUPLED RESPECTIVELY TO ONE AND THE OTHER OF SAID PISTONS, SPRING MEANS COUPLING EACH OF SAID PISTONS TO STATIONARY PORTIONS OF SAID HOUSING FOR BIASING SAID PISTONS TOWARD AN INTERMEDIATE POSITION, AND MEANS FOR CONTROLLING SAID CENTRAL VALVING MECHANISM SO AS TO CAUSE RECIPORCATION OF SAID PISTONS SUBSTANTIALLY IN UNISON ALTERNATELY OUTWARDLY AND INWARDLY RELATIVE TO THE INTERIOR OF THE HOUSING THEREBY VARYING THE INSTANTANEOUS VOLUME OF SAID HOUSING.