US2407328A - Sending and receiving apparatus - Google Patents

Description

E. E. TURNER, JR

SENDING AND RECEIVING APPARATUS Sept 1%, 194% Filed June 25 1955 V 2 Sheets-Sheet 1 ammwm 2m INVENTOR. DWIN E. TURNER JR.

p my E. E. TURNER, JR 2,47,328

I SENDING AND RECEIVING APPARATUS Fi 1ed Jun 25., 1955 2 Sheets-Sheet 2 INVENTOR.

:. M W i A OEY.

' EDWIN ETURMER JR.

Patented Sept. 10, 1946 TNT OFFICE SENDING RECEG APPARATUS Edwin E. Turner, Jn, West Roxbury, Mass, as-

signor, by mesne assignments, to Submarine Signal Company, Boston, Mass, a corporation of Delaware Application June 23, 1933, Serial No. 677,179

Claims. 1

The present invention relates to compressional wave transmitting and receiving apparatus and more particularly to compressional waves of higher frequencies, which include waves of the order of 10,000 cycles or more.

As a matter of fact the present invention relates perhaps more particularly to the transmission and reception of waves which in the medium in which they are transmitted have a Wave length of approximately less than one-half a foot. In water this limit is placed around 10,000 cycles, whereas in air, due to the lower velocity transmission in the air itself, the frequency may be around 3,000 cycles.

In the present invention the applicant has discovered that it is possible more readily to produce a plane wave by the use initially of a small radiator coupled with a transformation means operating directly with the medium in which the ultimate propagation is desired. In the present invention the dimensions of the element coupling the compressional wave transmitting and receiving device with the propagating medium preferably transforms the plane wave from a dimension of less than a wave length of the compressional wave which is propagated to one of a great number of wave lengths. This is accomplished by the use of an exponential horn in which the small end is substantially less than a wave length of the sound to be produced, whereas the large end is many times the wave length of the sound in the propagating medium.

The inventor has further discovered that sounds of higher frequencies are efliciently produced by a magneto-strictive vibrating unit in Which one end of the unit is substantially free and executes the relatively large vibrations, Whereas the other end of the unit operating in the sound propagating medium produces smaller vibrations.

The applicant has discovered that, although large mechanical forces may be built up in a magneto-strictive longitudinally vibrating system, unless the elements are allowed considerable freedom of vibration the losses due to hysteresis and other effects considerably reduce the efiiciency of the system. In order to operate most efliciently the applicant has found that a maximum vibration of the magneto-strictive element is necessary where the electrical forces are applied in order to produce a substantial back electro-motive force to prevent the abnormal absorption of electrical energy through hysteresis and other means in the magnetostrictive vibrating unit.

In overcoming these harmful effects, and in utilizing the longitudinal magnetostrictive videsired the node itself may be in the heavier unit,

although for different purposes it is far more efficient to have the nodal point in the lighter unit, as will appear from the discussion given below.

In the system of the present invention the vibrating unit may be considered as a combination of a concentrated mass against which the resonant or tuned system operates, the two elements being so combined that the larger amplitude of motion in the tuned element is converted to a smaller amplitude of motion in the mass element with a corresponding greater force however.

Besides the features above discussed, which will be explained more fully below, it may also be noted that in the-present invention the inventor has mounted the longitudinally vibrating systems at a node by a special means of mounting which is superior not only for the transmission of vibrating energy but also for the reception of vibrational energy in eliminating noises other than the compressional waves which it is desired to receive. It may be remarked that the present system is particularly designed and useful for the reception of high frequency compressional waves above a definitely special limit and that the receiver itself acts to cut out and eliminate all compressional waves below a certain frequency.

In this respect therefore the present invention is particularly applicable to use in submarine signaling in which there is always present a great deal of so-called water noise due to motion of the propellers, the movement of the ship through the water and the operation of machinery on board the vessels transmitted through the water through the outside shell. Many of these vibrations are below a frequency of 10,000 cycles and in the present invention, therefore, these are substantially eliminated.

The present device will act both as a transmitter and as a receiver and it may be installed in the skin of a vessel exposed directly to the outer water or there may be provided a covering over the outer opening to ensure a dead water space within the exponential horn itself.

The present invention will be more fully described in connection with the drawings in which Figure 1 shows in section an embodiment of the invention. Figure 2 shows a modification, Figure 3 shows a further modification, Figure 4 an elevation of Figure 3. Figure 5 a further modification of a detail of Figure 4, Figure 6 a further modification of the structure shown in Figure 4, Figure 6A shows a plan view of the modification shown in Figure 6, Figure '7 a detail of construction of Figure 6 and Figure 8 a diagrammatic illustration of the operating unit employed.

In Figure l the unit may be mounted in the skin of a vessel by means of a heavy flange 2 to which the exponential horn 3 is riveted by means of rivets 4, The exponential horn has an opening 5 which is several times the wave length of the sound produced in the medium. The opening 5, as will be noted in Figure 2, may be closed by a one-half wave length plate 6, clamped to the horn by means of bolts 1, or a very thin diaphragm may be used simply to prevent the rush of water at the surface of the horn. In the case where the plate 6 is made one-half wave length thick it will be noted that the same phase is produced on the external side of the plate as is impressed upon the internal side, In this case the plate itself will have no efiect in providing an additional mass at the end of the horn as is the case where a thinner plate is used. In the small end of the horn there is positioned the sound producing or receiving element 8 which extends part way in the end of the horn and practically fills the entire space at the end of the horn so that there is no sound released around the operating unit. A passage '5 may be provided at this end of the horn with a valve lil whereby water may be allowed to come through to relieve any air bubbles which may be at this end of the horn.

The passage 3 may be connected with the tube H, which may be extended upward to the water level, as indicated in Figure 1, so as to allow the escape of air bubbles which may be at the upper end of the horn without relieving the pressure at this point of the horn.

The sound producing or receiving element 8, as illustrated more particularly in Figure 8, is composed of a solid section l2 and a tube section it. The whole element preferably having a one-half wave length resonance with the nodal point, as illustrated, at the point El near the solid part H2 in the tube. It will be seen from Figure 8 that the tube It is free to vibrate and it should be noted that a greater part of the energ is always present at the hollow tube end, thus producing at this end a substantially large vibration while a relatively smaller vibration is produced at the radiating end of the part l2. From the principle of the mechanics of the transformation of amplitude, it will be noted that correspondingly the radiating end of 2 has a much larger force than is present in the element l3 where the power is established by the interaction of the coil and tube and correspondingly, therefore, sufficient power is provided at the radiating end of I2 to operate it in an unimpeded manner in the water.

While the unit illustrated in Figure 8 is shown as one-half wave length long it is obvious that other wave length dimensions may be used, either one-half or one-quarter multiples of the resonant frequency. The chief characteristic of the present invention in this respect being the means of ransforming large mechanical amplitudes where the electrical forces are applied to smaller me- 4 chanical amplitudes where the compressional wave energy is transferred to the water.

In Figure l the vibrating element 8 is supported by the ring i? which may be sweated or welded to the vibrating unit at the nodal point, as illustrated in Figure 8. The vibrating element is enclosed in a casing M which is made water-tight to the flange E5 of the horn 3 by'means of the bolts iii and a watertight gasket 15.

The ring l! is clamped rigidly at the end of the horn face by means of the bolts [8 and a clamping ring H]. on either side of the clamping ring ii are provided acoustically insulating sheets of rubber, cork or the like 2| and 2| so that no sound energy transmitted through the walls of the horn impress mechanical vibrations upon the vibrating element.

Surrounding the tube :3, within the casing I4, is a coil as which may be used for impressing both the alternating current and direct current upon the tube it. Instead of this arrangement the case is may be made permanently magnetic for instance by making it from cobalt steel to furnish the polarizing flux for the magnetostrictive unit. The alternating current is impressed for transmitting compressional waves. The coil 20 may be used both for transmission and reception, and the direct current may be impressed upon the coil to establish a desired magnetization of the magnetostrictive element. The magnetic circuit for the tube element it may be completed through the core 22 extending from the back of the casing into the tube I3, the flux circuit then being completed through the casing l4 and the end of the born The stunting box 23 may be provided for conducting the leads to the inside of the casing for operating the electrical elements within.

The vibrations produced at the vibrating end of the vibrating unit 8 directly impress into the water linear amplitudes which are transformed into plane wave amplitudes of much smaller linear dimensions at the large end of the horn 5. The end of the horn 5 is sufiiciently large, compared with the wave length of the sound to be produced, to produce a directive effect and similarly, for the reception of compressional waves, the horn is directive for frequencies above a certain limit. This limit is 1(),000 cycles or more, while the cut-off frequency for the sound waves is about 3000 cycles.

In Figure 3 a modification of the device shown in Figure 1 is illustrated. Here a group of independent units til, 30, 35), etc., are mounted upon a diaphragm or transmitting plate 3!. The units 3! may be nested together in squares or other regular figures which will nest to cover the entire surface of the plate 3!. The units 3%] include on their lower part, as shown in Figure 4, an element 32 having an exponential section shaped as shown in Figure 4. Mounted at the end of the exponential horns 32 are units which are composed of weights 34 and longitudinal rods 35 surrounded by coils 20 suitably supported by supports 55 which may or may not be hollow. The elements 34 and 35 form a vibrating unit to convert a large vibration at the end 35 into a smaller vibration in the mass 33. The unit 33 corresponds to the unit 8 in Figure l, but as has been remarked above comprises in part a concentrated fixed mass in which very little elasticity is present and a distributing mass 35 wherein the electrical forces are converted into mechanical vibrations. In this arrangement the rod 35 and the mass 34 serve to transform the amplitude of motion from the generated source to the point where the vi-' brations are impressed upon the exponential horn. The rod 35 and the mass 3% form one-half wave length system with the node near the mass 34. In this case the rod moves freely at one end with a large amplitude and impresses a small amplitude by means of the mass 34 into the horn. The energy impressed into the horn obeys the usual laws of propagation of vibrational energy in a horn, and the horn S2 is not considered in this respect a mass, although its relation to the mass .3 3 may have some effect in modifying the effective proportion of this mass in the system.

In the discussion in the present application the word elasticity is used in somewhat a nontechnical sense as referring to the vibration and non-vibration of the elements going to make up the system. In this respect if the element has substantially no difference in amplitude of motion between two points in the direction of the propagation of the compressional wave energy, it is considered non-elastic whereas if the difference is large, it is understood as having a great elasticity. In this sense of the word the term is somewhat non-technical. An illustration of this may be understood from Figure 8 in which the mass l2 has relatively little vibration while the tube l3, subjected to the vibration impressed by the coil 29, is relatively large. In this case the force in the tube i3 is all concentrated in the shell, whereas at the end of the tube I3 adjacent to the end portion l2 this vibration is spread over a uniform mass.

In connection with the use of the words distributed mass and concentrated mass it is intended that these terms should be construed together, with reference in particular to the wave length propagated in the material. A concentrated mass is to be considered a mass of relatively substantial weight in which the vibrational energy at the point of input and the vibrational energy at the point of output have substantially the same phase; that is to say, with reference to Figure 6 the mass associated with each tube is considered large and, further, has substantially the same vibrational phase at the point where the tube joins the mass as it has on the other side where the vibrations are impressed into the propagating medium.

The units 32 covering the entire plate 3| may be secured thereto in any suitable manner as by welding and may be operated in synchronism if desired, or they may also be operated with a phase difference to produce a directive beam other than normal to the plate 3|. That is to say, the applied electrical currents may all be operated with the same current phase so that there is no lag between the amplitude and phase of the electrical forces operating on one. rod from that on another, or the electrical energy may be applied to produce different current phases in various elements so that the vibrations produced will have different phases in one unit from that in the other. If all the elements are operated simultaneously in the same phase, the wave produced will progress perpendicularly to the radiating surface. If, however, progressive phases are applied to different rows of units, the beam may be diverted from the direction of the normal at an angle depending upon the phase difference established between different rows of units. The phase differences in applied electrical energy may be obtained in any well-known manner as, for instance, by the use of a multi-phase generator or some retardation device to delay the time phase of alternating current applied to different rows or units. The device shown in Figures 3 and 4 may be installed in the skin of a vessel, as illustrated in Figure l, or it may be installed in such a manner that it may be rotated about an axis, as for instance on top of a submarine or in a device which may be extended below the bottom of a vessel.

The units 32 differ from the horns of Figure 1 in that they are solid structures and maintain substantially maximum amplitudes at both ends. In this respect the units may be short as compared with the wave length or if they are longer than a wave length phase conditions are such that maximum amplitudes are maintained whether the phases are the same or apart; that is to say, if the element 32 is long as compared to the wave length, the only criterion to small end without change and without loss at the resonant frequency.

The total forces at the ends of the horn are the same but the force per unit area at the small end of the horn is greater than at the large end. The horn therefore reduces the force per unit area at the water end and enables maximum output into the water.

In Figure 5 is shown a modification of the element shown in Figure 4. Here the exponential horn 36 is directly connected to a tube 31. The nodal point in the tube 37 being near the small end of the horn 35 so as to convert, as illustrated by 0, vibrations of large amplitude in the tube 3'! to vibrations of smaller amplitudes and larger forces at the small end of the horn 36, thereby coupling the tube to the horn in such a way as to match the operating characteristics of the coupled elements.

In Figures 6 and I the system is a half wave length system in the direction as marked at the side of the figure. Here each tube it) may be sweated or force fitted into a plate 4! which may be supported by a thin flange 5! of the type indicated in Figure 2' and be bolted or held in any suitable fashion to the skin 2 of the vessel, and separate coils 42 may surround the tube. The tube it, together with the plate 4!, form a half wave length system, or a system having a multiple of a half wave length, or such a system in which the nodal point is positioned somewhat near to or in the plate 4| with respect to the tube 40. In Figure 6A there is shown a plan view of the arrangement shown in Figure 6. From this figure it will be noted that the tubes 40 cover substantially the entire plate. In this manner,

therefore, when all of the tubes are energized in the same phase, the entire plate will be vibrated with the same motion over its entire surface, thereby producing a beam of compressional waves when the size of the plate itself in its linear surface dimensions is many times the wave length of the vibrations to be produced. In this manner, similarly as in Figure 8, the desired large electrical vibrations are converted into smaller but more powerful vibrations for energizing the plate 4!. Similarly as in Figure 4 the plate 4! may be operated to move as a whole and preferably this is the method of operation, since the plate M is substantially a rigid mass and should be oper- 7 ated in the same phase throughout its surface.

In Figure 7 an enlargement is shown of a single tube 50 in the plate ii, showing the sweating of the tube 40 in the plate by means of which the tube is held in place.

It may be noted that the device in Figure 2 is particularly adaptable for use when the static pressure at the Vibrating unit is not sufficiently high to prevent cavitation. In this case artificial static pressure as by tube 50 may be placed upon the liquid in the horn in any of the usual ways so that the liquid at the end of the vibrating unit will be at a higher pressure than the medium abutting the outside of the plate 8.

Having now described my invention, I claim:

1. A device for transmitting and receiving compressional waves comprising a casing, an exponential horn mounted at one end of the casing, a uniform rod having a solid end and a hollow section, means mounting said rod in the small end of the horn, said means supporting said rod at its nodal point and a coil surrounding the hollow section of the rod, said hollow section being magnetostrictive.

2. A device for transmitting and receiving compressional waves comprising a casing, an exponential horn mounted at one end thereof, a rod filling substantially the entire end of the horn, magnetostrictive means formed as a part of the rod and a coil surrounding said means for applying vibrational energy thereto.

3. A device for transmitting and receiving compressional waves comprising a casing, an exponential horn mounted at one end thereof, a reso nant rod, means supporting said rod at its node and positioning the same at the small end of the horn, said rod being free at its other end and an electrical coil surrounding the rod for applying vibrational energy thereto, the rod being at least in part magnetostrictive.

4. A device for transmitting and receiving compressional waves including a diaphragm, a plurality of magnetostrictive vibratory units mounted on said diaphragm, each unit having the form of a solid exponential horn, a mass attached to the end of the horn and a magnetostrictive unit mounted thereon.

5. A device for transmitting and receiving compressional waves including a diaphragm, a plurality of magnetostrictive vibration units mounted on said diaphragm, each unit having the form of a solid exponential horn, a mass attached to the end of the horn, a magnetostriotive longitudinally vibrating rod coupled to said mass to provide a node in the rod near or in the mass and electrical means for vibrating the rod.

6. A devi e for transmitting or receiving compressional wave energy of high frequencies in water comprising an acoustic horn having an end opening large as compared to the wave length of the wave transmitted in the medium. and the other end smaller than the Wave length, a magnetostrictive vibratory unit, means mounting said unit in the small end of th horn, said unit having a radiating element substantially filling the area at the small end of the horn and means for energizing the same.

'7. A device for transmitting or receiving compressional wave energy of high frequencies in water comprising a horn having a large end opening to the water, a magnetostrictive element substantially filling the small end, means for mounting said element at the small end of the horn, means acoustically insulating the element in its mounting and an electrical coil coupled to the 8 magnetostrictive element for operating the same. 8. In a device for transmitting and receiving high frequency compressional waves, a horn having an opening large as compared with the length of the wave to be transmitted and a plate mounted at the large end of the horn, said plate having a thickness of one-half wave length of the Wave transmitted in the material of the plate.

9. A device for transmitting and receiving high frequency compressional waves of approximately 10,000 cycles per second and higher in water including a, magnetostrictive rod having one end free and the other end for radiating to the propagating medium, said rod having throughout a uniformly distributed mass, meanshaving a concentrated mass positioned at the radiating end of the rod, said concentrated mass and rod forming substantially a one-half Wave length system at the frequency the system is to operate with the node in the rod near the concentrated mass, and a coil surrounding said rod for energizing the same.

10. A device for transmitting and receiving compressional waves including a solid metallic plate, a large number of magnetostrictive rods, each having one end mounted in said plate and the other ends free, the rods having a uniformly distributed mass and forming with the plate a half wave length system at the frequency the system is to operate with the nodes in the rods near the plate and coils surrounding said rods for energizing the same.

11. A device for transmitting and receiving compressional waves including a solid metallic plate, a large number of magnetostrictive hollow rods, each having one end mounted in said plate and the other end free, the rods having a uniformly distributed mass and forming with the plate a half wave length system at the frequency the system is to operate with the nodes uniformly positioned in the rods near the plate and coils surrounding said rods for energizing the same.

12. A device for transmitting and receiving compressional waves including a solid metallic plate, a large number of magnetostrictive hollow rods, each having one end mounted in said plate and the other end free, the rods having a uniformly distributed mass and forming with the plate a half wave length system at the frequency the system is to operate with the nodes uniformly positioned in the rods near the plate and a, ICOil surrounding each of said rods for energizing the same.

13. A device for transmitting and receiving compressional waves including a solid metallic plate, means supporting said plate for allowing substantially uniform free vibration normal thereto over its entire surface, a large number of magnetostrictive hollow rods, each having one end mounted in said plate and the other end free, the rods having a uniformly distributed mass and forming with the plate a half wave length system at the frequency the system is to operate with nodes uniformly positioned in the rods near the plate and coils surrounding said rods for energizing the same.

14. A device for transmitting and receiving compressional waves including a solid metallic plate, a large number of magnetostrictive rods, each having one end mounted in said plate and the other end free, the rods having a uniformly distributed mass and with the plate forming at least a half wave length system at the frequency the'system is to operate with the nodes in the rods near the plate and coils surrounding said rods for energizing the same.

15. A device for transmitting and receiving a beam of high frequency compressional waves including a solid metallic plate of substantial thickness but less than one-quarter Wave length of the compressional wave to be transmitted normally therethrough and having length and breadth dimensions substantially large as compared to the Wave length to be transmitted, a 5' large number of substantially uniform, free magnetostrictive rods, means for mounting said rods 10 on one side of said plate substantially uniformly covering the entire surface of said plate, said rods being mounted perpendicular to said plate and being free at the end not mounted in the plate, a plurality of electrical coils surrounding said rods for vibrating the same magnetostrictively in response to variation in the magnetic flux induced therein by said coils, said plate and rods forming one-half wave length system at the frequency that the system is to operate with the node in the rods near the plate.

EDWIN E. TURNER, JR.

Images