US2402697A - High-frequency vibrator - Google Patents

Description

June 25, 1946. E. TURNER, JR A2,402,697 R HIGH FREQUENCY VIBRATOR Filed MEW 18, 1938 2 Sheets-Sheet 2 *Y nvvmvfk Y LEDWINEIURNER JR. Y .LV Y Lf-MNH.

, sides of the tube elements.

Patented June 25, 1946 A 2.44am mon-FaEQUENoY vmna'ron Edwin E. Turner, Jr., West Roxbury, Mass., as-

signor to Submarine Signal Company, Boston, Mass., a corporation oi.' -Maine Application my 18, 193s, serial No. 208,568

l The present invention relates to a device for producing compressional waves and more particularly to such a ydevice for producing supersonic frequencies in which a. radiating element is so dimensioned with regard to the frequency to be produced that the compressional waves radiating form a beam.

The principles of the present invention may be applied both to compressional wave transmitters operated either electrodynamically or by magnetostriction methods and the device may be applied both for sending a beam of compressional s claim. (ci. 1ra-sse) waves in air or in water but the invention pringreat number of magnetostrictive rods cach of which is energized in the same manner by coils surrounding the rods. Another system which'has been employed is to construct the vibrating system oi' a heavy plate at the back of which are projected concentric cylinders of conductive material.

In these systems vas described in my prior patent application SerialNo. 677,179, filed June 23, 1933, the plate and rods formed a vibrating unit of the equivalent of a half of a wave length in which the node was positioned-in or near the plate but no particular attention was paid to the method of supporting the vibrating element in such a manner'as to produce the greatest eiiicicncy in the operation of the system.

In accordance with the present invention the system is so designed that the nodes in the'system are situated in the rods or tubes and are all in substantially the same line so that the plate itself may be supported to allow the greatest freedom of motion of it as the radiating element.

I'he present invention will be more fully de scribed in connection with the embodiments described in the specification below and shown in the accompanying drawings in which Fig. 1 shows a sectional elevation of the device in one form; Fig. 2 shows a partial similar sectional elevation as shown in Fig. 1 modiiied vin detail, however, from this construction; Fig. 3 shows another modiiication of the device shown in Fig. 1: Fig. 4 shows a modification of the device shown in Fig. 3; and' Fig. 5 illustrates a further detail of the modification shown in Fig. 1 with driving coils on both In Fig. 1, I indicates the radiating element with a flat surface on the outer side which is to be exposed to the propagating medium and with concentric tubes or rings I, 4 and l, respectively, on the inner side which are preferably formed as 2 an integral part of the radiating element. The

plate I with the tubes 3, 4 and 5 is preferablyl a forging which is machined down to exact dimensions to make the tubes concentric with one another and spaced at an equal distance apart. These tubes are of such material and dimensions that together with the plate l which should be no greater in thickness than one-eighth of a'wave length of the compressional wave to be propagated in the material itself, the system forms a one-half wave length vibrator for each and every tube ln which the nodal lines of each tube lie in the same plane defined by the line C-C (or 6) as indicated in the figure. The plate l, as indicated in Fig. 1, has an outwardly extending flange 1 which is extended backwards of the plate by means of the shoulder 8 so that the flange l likewise centers in the same plane as that indicated by the line C--C (or 6). The vibratory system is clamped by means of the flange between the outer plate 9 and the inner casing l0..

The tubes 3, 4 and E are energized at their top portions which are situated in magnetic fields formed by outer and inner pole elements. The center tube 3 .has direct current flux owing across from the center pole piece' ll to the outer pole piece l2, the return path being through the cylinder I l and the top plate i4.' Similarly the -end oi' the tube 4 rests in the magnetic field faces, as indicated in Fig. 5, in which coils are on both the outside and the elements;

In. the system as shown in Fig. 1 the energizing coil is indicated as extending about one-third the distance from the end of the tube. .As amatter of fact it is preferable to extend the appliinside of the pole face kcation of the energizing force substantially. further down the tube towards the nodal plane on the line C-C (or 8) and it shouldbe noted in this connection that assuming the tube vibrates sinusoidally, which it may well do; the amplitude of motion one-half the distance from the end of the tube is still seven-tenths of the amplitude at the end of the tube and therefore substantially the same reactance will take place to the driving force and permit a greater and more eflicient application of the driving force over the system;

With an arrangement such as shown in Fig. 1

the entire plate l moves with a uniform amplitude throughout the entire surface and this is substantially true not only of the iront surface other words, the entire plate moves as a. uniform mass, the elastic force being exerted entirely between the line of node and the plate in the tube. In order to maintain this symmetry, therefore, it is necessary to position the supporting flange 'l in the rear of the plate in the same plane as the nodal plane and to allow the extension and compr on of the supporting web to be confined enely within the shoulder 8 and the ilane 1 so t at the plate may be freely supported.

, rear portion of said plate into said nodal plane.

A modiiication of this system is shown in Fig. c

2. In this modificationthe plate Iii is provided with a flange 3i extending at right angles outward from the back of the plate. 'I'he plane of the nodes is positioned at the center of this flange,

however, by undercutting the tubes as indicated at l2, I3 and Il. These tubes are cut sufliciently,

into the plate so that their nodal planes coincide with the plane of the flange 3i.

In the modification shown in Figs. 3 and 4 the same principle as explained in connection with Figs. 1 and 2 is applied to a magnetostrictive driving system. In Fig. 3 the plate 40, which is the equivalent of I in Fig. l, is provided with a' great number of magnetostrictive small tubes or rods Il, 4I, Il, etc., each surrounded by coils 42, I2 for energizing and driving the magnetostrictive tubes. The tubes 4I may be fixed in the plate ll in any suitable way which in itself forms no part of the present invention. In this system as indicated. however, the tubes are so proportioned and,

ciding with the plane shown in the line A-A of Fig. 3. The nange Il is extended backwards from the plate Il and is situated in the same plane as that of the nodes as indicated by the line AA.

In Fig. 4 the same driving means is shown as in Fig. 3 but here the plate It is undercut as indicated by Il, Il, Il, etc., to receive the small rods or tubes 52 which are of magnetostrictive material and driven by means of the coils 53. Line B--B indicates the plane of the nodes in this iigure.

A modification of the arrangement of Fig. 1 is indicated in Fig. 5 in which both inner and outer coils lll and II- are provided for driving the tubes I, 4 and l. The alternating current ux due to these coils is induced in the end of the tube which is of conductive material as, for instance, some form of copper or copper alloy and is in eect an electrodynamically operated system in which the tubes are the current conductors in the moving magnetic eld.

In the present invention the plate and the rods or tubes at the rear thereof form a vibratory system preferably of one-half wave length, the plate being of substantial thickness and uniform and the tubes likewise uniform so that the nodesof the system lie in the plane near the plate.. For most eiiicient operation the Plate should be of substantial thickness but not so thick that appreciable wave motion occurs in the material .of the plate in a direction perpendicular to its surface. In other words, in the present system the front and rear of the plate move with substantially the same amplitude.

Having now described -my invention, I claim:

l. Means for transmitting a beam of compressaid means providing a supporting flange lying in said nodal plane for supporting said plate.

2. Means for transmitting a beam of compressional waves comprising a plate, a plurality of concentric tubes formed as an integral part of said plate and projecting rearward therefrom normal to said plate, said tubes and plate forming a vibratory system having a nodal plane po sitioned in said tubes nearsaid plate, means for supporting said plate at the edge thereof comprising a flange extending from the rear portion of said plate, said means having a supporting element lying in the plane of said nodes.

3. Means for transmitting a beam of compressional waveseomprising a heavy plate having substantial thickness, a plurality of concentric tubes formed integrally with said plate but undercut inthe plate whereby a vibratory system is formed having a nodal plane coinciding approximately with 4the rear surface of said plate, a ange extending from the rear edge of said plate into said nodal plane having a supporting element coinciding with said nodal plane.

4. Means for transmitting a beam of compressional waves comprising a plate having a thin flange projecting from the rear of the plate and outward forming a supporting web for said plate. a plurality of magnetostrictve rods mounted on the rear of said plate and having a node' near the plate line in a single plane, said plane coinciding with the plane of said supporting web.

5. Means for transmitting a beam of compressional waves comprising a plate having a thin iiange projecting outward from the baci; surface /of the plate forming substantially a continuous surface with the back surface of said plate, a plurality o1' magnetostrictive rods mounted in recesses cut in the rear of the plate, said rods having nodes lying substantially in a single plane and said recesses being cut so that the nodal plane coincides with the plane of said iiange.

6. Means for transmitting a beam of compressional waves comprising a plate having a thin web extending outward from the rear edge of the plate and forming a supporting web for supporting the plate in Vibration, a plurality of concentric tubes mounted on the rear of said plate and having nodes lying in a single plane coincident with said supporting websaid tubes being of conductive material and means immersing the free ends of said tubes in an alternating current magnetic iield to substantially one half the distance to said nodes.

7. Means for transmitting a beam of compressional Waves comprising a plate having a thin web extending outwardly from the edge of the plate for supporting the plate, a plurality of concentric tubes mounted on the rear of said plate, means immersing the free ends of said tubes in an alternating current magnetic field compris ing means forming a cylindrical direct current magnetic eld across said tubes, and coils adapted sional waves comprising aplate and elements Y projectingfrorn the-back of the plate forming ins in the saaie plane. means extending from the EDWIN E. TURNER, Jl.

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