US2730067A - Apparatus for generating sonic or supersonic mechanical oscillations - Google Patents

Description

Jan. 10, 1956 A. scHAUFLER 2,730,067

APPARATUS FOR GENERATING SONIC OR SUPERSONIC MECHANICAL OSCILLATIONS Filed March 19, 1953 United States Patent "O APPARATUS FOR GENERATING SONIC OR .SUPERSONIC MECHANICAL OSCILLATIONS Erwin Alfred Schauller, Erlangen, Germany, assignor to Siemens-Schuckertwerke Aktiengesellschaft, Berlin-Siemensstadt, Germany, a German corporation My invention relates to mechanical oscillation generators for imparting sonic pressure waves to a liquid or gaseous medium, such as air, in an enclosed or open oscillation-receiving space, the term sonic being meant in this application and in the claims to kinclude audible as Well as supersonic frequency ranges.

It is an object of my invention to provide a sonic generator of higher power translating capacity than heretofore obtainable with sonic generators of comparable size. It is also an object of my invention to devise a sonic oscillation generator of improved eiiiciency for the application of sonic energy to a uid oscillation carrier. A further object is to provide a sonic oscillation generator especially suitable for industrial applications; and it is also an object to provide a simple mechanical oscillation amplifier of a high amplifying ratio.

To achieve these objects, l equip apparatus according to my invention with a positive-pressure chamber iilled with the same fluid medium as that to be sonically excited but having a higher pressure, and with a negativepressure chamber also containing the same medium but under a lower pressure than obtaining in the space to be sonically excited. I further connect the two chambers individually with the oscillation-receiving space by respective passages and provide these passages with a cyclically driven flow control device in the nature of a periodic flow transfer switch which puts the media in the two chambers alternately and rhythmically into a merging and oscillation-conducting touch withthe medium in the space to be sonically excited.

According to another feature of my. invention, I interconnect the two above-mentioned' chambers with each other by passage means which contain a pump or other pressure-producing means whose suction side is joined with the negative-pressure chamber and whose pressure side is joined with the positive-pressure chamber so as to establish and maintain the desired differential pressure magnitudes.

According to still another feature of my invention, the above-mentioned flow transfer control device com prises a movable plate member with one or more holes that, due to movement of the plate member, alternately open the passage between the respective two chambers and the space to be sonically excited.

The foregoing and other features of my invention will be apparent from the following description in conjunction with the drawings, in which- Y Fig. l shows schematically a sonic oscillation generator according to Vthevinvention in a design kept simple for better explanation; I

Fig. 2 is a lateral sectional view of a more elaborate apparatus also embodying the invention;

Fig. 3 is an axial view onto a disc member pertaining to the apparatus of Fig. 2, the view being from the left of Fig. 2;

Figs. 4 and 5 are explanatory and illustrate respec-v tively two different operating positions of segments of Tice plate-shaped parts pertaining to the apparatus shown in Figs. 2 and 3;

Fig. 6 is similar to Fig. 4 and shows the same parts in a somewhat modified design;

Fig. 7 is a lateral sectional view of another sonic apparatus somewhat modified over that shown in Figs. 2 and 3; and

Fig. 8 is a similar but only partial View of the apparatus of Fig. 7, showing it in a different operating position.

The essential features and operation of a sonic oscillation generator will first be explained with reference to the simple schematic example illustrated in Fig. l.

The generator serves to impart sonic oscillations to a fluid medium, for instance air, within a container 1. Two enclosed chambers 2 and 3 serve to provide the pressure difference needed for exciting the medium in the space of container 1 to sonic oscillations. Both chambers 2 and 3 contain the same iiuid medium, for instance air, as the container l; but chamber 2 is kept under positive pressure and chamber 3 under negative pressure relative to the pressure in container 1. That is, the pressure in chamber 2 is higher and the pressure in chamber 3 is lower than that obtaining in container 1. To produce and maintain the desired pressures, the chambers 2 and 3 are interconnected by a conduit passage which includes a pump 4 or other pressure generator so connected that air is inducted from chamber 3 and is pressed into chamber 2, as is indicated by respective arrows A and B. Chambers 2 and 3 are connected with the space of container 1 by respective conduits or pipes into which a slider 5 is inserted to act as a flow transfer switch. The slider S has two holes 5b and 5c of which only one at a time is in registry with one of the respective conduits. The slider is reciprocable in the direction indicated by a doubleheaded arrow C and, when in operation, is driven to alternately place its holes 5b and 5c into registry with the respective conduits. Thus the air path through each conduit is alternately closed and opened so that the medium in container 1 is alternately` merged with the media in the positive-pressure chamber 2 and the negative-pressure chamber 3.

. Consequently, the space to be sonically excited is subjected to positive pressure and negative pressure depending upon the position of the moving control slider 5. Since this occurs in a periodic repetition and in the rhythm controlled by the slider drive, the medium in space l. is excited to mechanical oscillations.

The reciprocating movement of the oscillation controlling slider 5 may be effected by any suitable drive means, for instance, a cam drive or an electromagnetic oscillator. An example of the latter type is shown in Fig. l as comprising an electromagnet 5d to be excited by aiternating Current so as to oscillate its armature or core, and thereby the slider 5, in a rhythm determined by the frequency of the alternating current.

The frequency of the generated sonic oscillations can be selected within wide limits. This frequency depends exclusively upon the frequency with which the owtransfer control switch is operated. For instance, if the movable switch member is actuated by an electromagnetic oscillator or shaker as shown in Fig. l, and this oscillator has an operating frequency of cycles per second, then the mechanical oscillations imparted to the space to be sonically excited have also a frequency of 100 C. P. S. Relatively slight forces are suflicient for operating the transfer switch. The oscillatory energy generated in the space to be sonically excited is independent of the power consumption of the transfer switch but depends upon the pressure magnitudes in the positive-pressure chamber and the negative-pressure chamber. These pressure magnitudes may be chosen as desired within very wide limits.

Consequently, an apparatus according to the invention also. represents a simple power amplier of mechanical oscillations.

For most applications of apparatus according to the invention, it is preferable to aim at keeping the volumetric fluid quantity or weight entering per time unitl into: the space to be sonically excited equal to the iiuid quantity or weight leaving that space when its connectionA with the negative-pressure chamber is open. Anyl thus necessary equalization can be effected by giving the connecting passages between the space and the respective two chambers respectively different cross-sectional dimensions depending, on the one hand, upon any given pressure ratio between the positive pressure and the pressure inl the space to be sonically excited, and on the other handi upon the `ratio of the pressure in that space to the negative pressure.

According to another feature of the invention, the inherently large power capacity of apparatus according to the invention may be further increased by joining the positive-pressure chamber as well as the negative-pressure chamber with the space to be sonically excited by a plurality or large number of conduits or other passages all controlled by the flow transfer device to open and close in the desired rhythm.

The passages from the positive-pressure chamber and from the negative-pressure chamber may directly and side by side communicate with the space to be sonically excited. However, these passages may also be joined with each other ahead of the oscillation space. This has the advantage of preventing the` occurrence of a progressive air movement within the oscillation space as may otherwise be caused between the pressure inlet opening and the pressure outlet opening.

The movable control member of the ow transfer switch consists preferably of a rotating, siren-type disc or of a plurality of such discs.

Several embodiments of apparatus according to the invention incorporating the above-mentioned modifications are illustrated in Figs. 2 to 8. In the following description of these illustrations, reference is made to air as a uid medium, although it should be understood that any other liquid or gaseous medium is likewise suitable for the purposes of the invention.

The apparatus according to Fig. 2 is equipped with a flow transfer switch which comprises a revolvable disc 6 drivable by means of a shaft 7 on which the disc is mounted. The disc 6 has a number (n) of holes 6b arranged in a concentric row along the disc periphery. Another disc 8 of the same diameter as the disc 6 is placed in coaxial face-to-face relation to disc 6 and has an annular zone in slidable engagement with disc 6. Disc S is also revolvable and driven by a shaft 9. When in operation, the shafts 7 and 9 revolve in opposite directions, as is indicated by respective arrows D and E. Disc 8 has a peripheral row of holes 8b and Sc whose number (2n) is twice that of the holes 6b in disc 6. The diameters of the holes in discs 6 and S are equal, and the two rows of holes have the same radial spacing from the common axis of the discs.

On the side of disc 8 facing away from disc 6, the holes 8b and 3c in disc S are alternately curved outwardly and inwardly, a view on this side of disc S being represented in Fig. 3. It will be seen that eachl hole 3b forms a duct which curves outwardly, while each alternate hole 8c forms a duct curving inwardly. While, as mentioned, one side of disc S slides on disc 6, the opposite side of disc 3 is in sliding engagement with an annular projection 10l of a housing 1l in which the two discs are revolvably mounted. The annular projection Il@ divides the space between disc S and housing 1t) into two chambers, namely an outer chamber l?. of annular shape and a centrally located, inner chamber 13. When the apparatus is in operative condition, the chamber 12 isy connected through a passage or conduit 12b with an air-pressure accumulator or the pressure side of a pump, while the chamber 13 is connected through. a. passage or conduit 13b. withv aV negativepressure accumulator or theA suction side of a pump, Consequently, the chamber 12' represents a positive-pressure chamber and the chamber 13 a negative-pressure chamber in accordance with the above-explained features of the invention. The outwardly curved holes 3b of disc 8 are continuously in communication with the positive-pressure chamber 12, and the inwardly curved holes 3c are continuously connected with` the negative-pressure chamber .113. The space to4 be sonically excitedy is located at the outer side of disc 6, that is at the right-hand side in the illustration of Fig. 2.

For explaining the operation of the apparatus, it may rst be assumed that the disc 6 is at rest, while the disc 8 is revolving. At the moment of operation represented in Fig. 2, each hole 8b of disc 8 registers with one of the respective holes 6b of disc 6, while the holes 8c of disc 8: are coveredl byV disc 6. At this moment, therefore, the holes 6b are all' connected through the outwardly curved holes 8b with the positive-pressure chamber 12 so that airfrom chamber 12 passesthrough the holes 3b and 6b into the oscillation space.

This is further apparentfroml the schematic illustrationin Fig. 4 showing respective segments of discs 8 andE 6 inv a mutual position corresponding to that of Fig. 2. The disc 8 has twice as many holes 8b, 8c as the disc 6. Schematically shown in each hole 8b is a dot to indicate that these holes are connected with the positive-pressure chamber. Each hole 8c is marked by a cross to indicate that these holes are connected with the negative-pressure chamber. The holes 6b in disc 6, as indicated by broken lines, are located beside the respective holes 8b of disc 8 that areA subjected to the positive pressure. Consequently, theholes 6b of disc 6 are also subjected topositive pressure as is indicated by a dot in' each hole 6b. If now in Figs. 2 and 4 the disc 8 is moved a smallamount untill the inwardly curved holes 8c register with the holes 6b of disc 6, as shown in Fig. 6, air from the oscillation space is inducted through holes 6b andi 8c intothe negative pressure chamber 13.

While in Fig. 4 all holes 6b of disc 6 are under positive pressure, these holes in Fig. 5 are all under negative pressure. FEhis, change is periodically repeated when the disc 8 is being continuously driven by its shaft 9. During the revolutionl ofV disc 8 over a distance corresponding to two of itsI hole spacings, that is from one pressure hole 8b to the next, the following effects will take place. At first, air is forcedl into the oscillation space from each hole 6b` of disc 6. Thereafter, an amount of air is drawn from the space back through the same hole 6b. Consequently, a periodic sequence of positive pressure and negative pressure is imparted to the oscillation space in the same manner as in the above-described apparatus according to.Fig. 1. Asa result, the air within the space is excited to sonic pressure oscillations of the desired frequency.

The movement of air through the holes during the increase and decrease of pressure corresponds to a time curve similar to a sinusoidal wave. In order to have the air movements .and hencey the oscillations as a whole follow a steady characteristic, the spacing between adjacent holes in disc, accordingV to another feature of the invention, is. made equal. to the hole diameter, that is, equal to the width of the holes. measuredl in the direction of revolution. The holes 6b in discA 6 are then spaced from each other byy three times the hole diameter. To prevent the occurrence of a progressive air movement in the space to be excited, the air quantity entering this space during one half-wave period of the pressure oscillation must be equal totheair quantity sucked, from the space during the next half-wave period. Therefore, care should be taken to have the same quantities or weights of flowing air pass through the same. holes of disc 6 with-in equal flowr periods. The quantity or weight of air passing through the holes depends upon the acceleration of the air occurring during the oscillatory travel of the air. This acceleration, in turn, is determined by the ratio of the pressure difference between the positive-pressure chamber and the space to be excited, and the difference between the pressure in that space and in the negative-pressure chamber. Due to this dependency of the air quantity upon the pressure conditions, the eiective cross-sectional flow area of the positive-pressure and negative-pressure passages must have a proper ratio to each other if best results are to be attained. Generally, therefore, the cross secion of the holes connected with the negative-pressure chamber is preferably made larger than the oW-traversed cross section of the holes communicating with the positive-pressure chamber. How this can be practicably accomplished is illustrated in Fig. 6 which, similar to Fig. 5, shows only segmental parts of the two cooperating discs 6 and 8. According to this modification, the holes 8b communicating with the positive-pressure chamber do not have a circular cross section but have an oval shape so that the above-mentioned requirement for equal flow quantities is satisfied.

The connection of the air passages between the chambers 12 and 13 on the one hand and the space to be sonically excited on the other hand, and particularly the design of the two perforated discs and their holes, can be modiiied in various respects. In the embodiment of Fig. 2, the holes 8b and 8c of disc 8 have an angularly bent shape. This has the eifect of impeding and braking the air movement to some extent. It is, therefore, preferable to give the holes a straight axis and an inclined arrangement as is illustrated in Figs. 7 and 8.

According to Fig. 7, the holes 8b communicating with the positive pressure space 12 are inclined with respect to the disc axis so that the holes 6b, when registering with holes 8b, are connected with the positive-pressure chamber 12 by a straight duct of minimized flow resistance. Since, in the cross section shown in Fig. 7, the inwardly directed holes 8c of disc 8 are not visible, Fig. 8 shows a portion of the same apparatus in a position of disc 8 where one of the holes 8c is located in the plane of illustration. In this position, the holes 6b are in communication with the negative-pressure space 13 through an inclined and straight duct formed by the hole 8c. In all other respects, the apparatus according to Fig. 7 and 8 is similar to that of Figs. 2 to 5, corresponding elements being designated by the same respective reference characters.

The frequency of the mechanical oscillations generated by the apparatus depends for any given number of holes upon the revolving speed of disc 8 relative to the disc 6. Since the mechanical strength of disc 8 is limited, its revolving speed cannot be increased to any desired high value. It is therefore preferable to also revolve the disc 6 in opposition to the revolution of disc 8 if the generated oscillations are to have a high frequency near the audible limit or within a supersonic range. Apparatus according to the invention can readily be designed for any desired high power outputs since, aside from the revolving discs, all parts of the apparatus can be given any desired mechanical strength. Besides, any twisting movement of the air due to the revolution of disc 8 may be compensated by the opposed revolution of disc 6.

With respect to the absolute magnitudes of pressure in the spaces 1, 2 and 3, the following should be understood. The pressure in the space to be sonically excited need not be equal to the atmospheric pressure but may have any desired larger or smaller magnitude. It is only essential that the pressure in the positive-pressure chamber be higher and the pressure in the negativepressure chamber be lower than that obtaining in the oscillation space. For instance, the positive-pressure chamber or the negative-pressure chamber may be given atmospheric pressure so that then the ambient atmosphere may serve as the negative-pressure chamber or as the positive-pressure chamber, as the case may be.

If the desired oscillatory operation or treatment requires a particular wave shape of the oscillations generated in the fluid medium, such wave shapes can be obtained by giving the holes a correspondingly modified shape.

It will be understood by those skilled in the art upon a study of this disclosure that the invention is not limited to the specific embodiments illustrated and described, but may be varied in diiferent respects without departing from the essence of the invention. For instance, instead of a single row of holes in the above-described disc, a plurality of concentric rows of holes may be provided, the positive-pressure and negative-pressure openings of the individual rows of holes being disposed either alternately in the same row or alternately in ditferent rows. In connection therewith, and depending upon the design of the positive-pressure and negative-pressure holes, a plurality of positive pressure chambers and negative pressure chambers may be provided. Of particular advantage is the provision of two concentric cylinders or other bodies of revolution being provided with respective sets of holes that cooperate in the same manner as described in the foregoing. For providing the necessary relative movement of the two concentric bodies, one or both may revolve, or, when the bodies are cylinder-shaped, they may be driven to reciprocate parallel to the cylinder axis. I claim:

l. Apparatus for generating sonic oscillations in a space containing a fluid medium, comprising a first chamber and a second chamber both containing the same fluid medium as said space, said first chamber continually having a higher pressure and said second chamber continually having a lower pressure than said space, passages connecting said respective two chambers with said space, and periodically operating flow transfer control means disposed in said passages to form part thereof and alternately closing said respective passages, whereby said media in said chambers are rhythmically and alternately merged with the medium in said space.

2. Apparatus for generating sonic oscillations in a space containing a Huid medium, comprising a first chamber and a second chamber both containing the same uid medium as said space, said first chamber continually having a higher pressure and said second chamber continually having a lower pressure than said space, passages connecting said respective two chambers with said space, and periodically operating llow transfer control means having a movable member extending across said passages and having respective openings registering with one of said passages at a time depending upon the position of said member, and drive means connected with said member for moving it cyclically to alternately open and close said passages, whereby said media in said chambers are alternately merged with the medium in said space. v

3. Apparatus for generating sonic oscillations in a space containing a iluid medium, comprising a first chamber and a second cham er both containing the same lluid medium as said space, said irst chamber continually having a higher pressure and said second chamber continually having a lower pressure than said space, passages connecting said respective two chambers with said space, and periodically operating flow transfer control means having a revolvable disc member extending across said passages and having .a row of openings in registry with one of said respective passages at a time depending upon the position of revolution of said member, whereby said media in said chambers are rhythmically and alternately merged with the medium in said space.

4. Apparatus for generating sonic oscillations in a space containing a fluid medium, comprising a rst chamber and a second chamber both containing the same fluid medium as said space, said first chamber continually having a, higher pressure and.- sad.. Second chamber, Continu.- ally having a` lower pressure than said, space, two. plate members disposed inface-to-face relation to each.'` other and being capableA of movement relative to, each other, one of said plate members having alternately arranged holes communicating with Said, first chamber and'with said second chamber respectively, saidV other plate member having holes. registerable with said, holes of said one plate member and. connecting said` space through said holes` of said one plate member with; one of said. two chambers, at a time depending uponA the instantaneous position, of said two plate members relative to,ea cl i other, and. cyclical drive means for impart-ing relative, motion to said: plate member, whereby said media in` said, chambers are rhythmically and alternately merged, with the medium in said space.

5. In oscillation generating apparatus. according to claim 4, said, holes disposed in said one plate member and communi'eatingV with. said first chamber having a smaller lluid-ow area than saidholes insaid same plate member communicating withI said second, C hambfl' so, as to minimize di'rferencesV in theweight of the mediumtlowing in opposite directions vduring equal'` periods, of time through, said first-named and saidsecond-nam edl holes respectively.

6. Apparatus for generating sonic oscillations in a space containing a uidy medium, comprising a; first Chamber and a second chamber both containingthe same uid medium as said space, said rst chamber continually having a higher pressure and said second chamber continually having; a lower pressune, than said space, two plate members disposed in-V face-tQ-.face relation to each other and being, capable of movement relative toY each other, one of said plate members having alternately arranged holes communicating with; said rst chamber and with said second chamber; respectively, said holes in said one plate member comprising` two groups havingy within the plate member; two. diierent respective directions, theholes ofl one group7 beingV directed outwardly, and the holes, of the, other group being directed inwardly and being arranged in` an. alternate sequence to saidholes of saidone group, said otherplatemmbervhaving. holes registerable with, said holes ci said one plate member and connecting said space through said, holes. of said one plate member .with oneof said two chambers at a time depending upon the. instantaneous position of said two plate members relative to`- eachV other, said holes in said one plate member arranged in a circular row and having a mutual'spacing equal to the width of elachrliovle in the peripheral directionV ofsaid row, and saidzholesinv saidA other plate memberV having aI corresponding mutual spacing equalto three times the Width of the holes, and cyclieel dlrive meansV for imparting relative motien Ato Said Plate members whereby said luid medium in said chambers is; rhythmically and alternately merged with the uid medium in said. space.

References,v Cited in the leA of this patent UNITED STATES. PATENTS 2,560,728 Lee July 17; 1951

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