SE470471B

SE470471B - Generator for acoustic pressure waves

Info

Publication number: SE470471B
Application number: SE9202758A
Authority: SE
Inventors: Jan Andersson; Bengt Holm
Original assignee: Conson Ab
Priority date: 1992-09-24
Filing date: 1992-09-24
Publication date: 1994-05-09
Also published as: SE9202758D0; SE9202758L

Abstract

Generator for acoustic pressure waves at audible frequency or inaudible frequency within the infrasound range. It comprises a system of magnets 2, 3, 3' which can be rotated about a central axis 1, and which magnets are arranged so as, by means of rotational movement of the system, to bring about induction currents in electric conductors 4 of a separate oscillation member 5 for bringing about pressure waves by means of the axial movements of the member. By virtue of the fact that the conductors or parts thereof are periodically, as a result of their position and direction relative to the movable magnetic fields, exposed to the effect of electrodynamic force, the oscillation member is made to oscillate, the frequency on rotational movement of the magnet system being defined by the periodicity in the change of the magnetic fields relative to the electrodynamically active parts of the electric conductors of the oscillation member. <IMAGE>

Description

470 471 Vid framtida tillämpningar av den nu föreliggande uppfin- ningen - inte minst vid industriellt produktionsutnyttjande av ljud för rörelseaktivering, s k industrisonik - skulle elektrodynamiska strömslingor hypotetiskt kunna utföras av supraledande material, vilket skulle innebära exceptionella möjligheter till ljudgenerering med nästan förlustfri om- vandling av rotationsrörelse till oscillationsrörelse. 470 471 In future applications of the present invention - not least in the industrial production utilization of sound for motion activation, so-called industrial sonication - electrodynamic current loops could hypothetically be made of superconducting material, which would mean exceptional possibilities for sound generation with almost lossless conversion of rotational motion to oscillating motion.

I angivet syfte utnyttjar den nu föreslagna generatorn ett roterande eller i vart fall vridbart system av permanent- eller alternativt elektromagneter. I motsats till den i det a föregående kort beskrivna magnetodynamiska metoden påverkas inte det oscillerande organet i den föreliggande uppfin- ningen med direkt magnetisk attraktion eller repulsion, utan det rörliga magnetsystemet inducerar elektriska strömmar i en eller flera strömslingor,.som är fästade vid oscilla- tionsorganet. I enlighet härmed har generatorn av det inled- ningsvis angivna slaget erhållit kännetecknen enligt patent- kravet 1.For the stated purpose, the now proposed generator uses a rotating or at least rotatable system of permanent or alternatively electromagnets. In contrast to the magnetodynamic method described above, the oscillating member of the present invention is not affected by direct magnetic attraction or repulsion, but the moving magnetic system induces electric currents in one or more current coils attached to oscillating. the body. Accordingly, the generator of the type indicated at the outset has obtained the characteristics according to claim 1.

För närmare förklaring av uppfinningen hänvisas till bifoga- de ritning, på vilken Figur 1 visar en vy i halvsektion av ett utförande av en in- duktionsgenerator för ljudalstring, driven av en elmotor, Figur 2 visar en periferiellt utbredd delprojektion av snit- tet A-A enligt Figur 1, med det rörliga magnetsystemet i visst läge, Figur 3 visar en projektion motsvarande Fig 2 men med en annan typ av strömslinga och med ett magnetfält uppdelat i två hälfter med olika fältriktning, Figur 4 visar en periferiellt förlängd slinga i två lägen relativt det i pilens riktning passerande magnetfältet.For a more detailed explanation of the invention, reference is made to the accompanying drawing, in which Figure 1 shows a half section of an embodiment of an induction generator for sound stringing, driven by an electric motor, Figure 2 shows a peripherally extended partial projection of the section AA according to Figure 1, with the movable magnetic system in a certain position, Figure 3 shows a projection corresponding to Figure 2 but with a different type of current loop and with a magnetic field divided into two halves with different field directions, Figure 4 shows a circumferentially extended loop in two positions relative to the in the direction of the arrow passing the magnetic field.

Med hänvisning till Figur 1, och såsom i det föregående del- vis beskrivits, är ett kring en central axel (1) rörligt magnetsystem (2) anordnat. Genom vridningsrörelse av syste- met, som innefattar ett flertal magneter (3), (3'), bildande periferiellt ordnade poler, induceras en elektromotorisk kraft i en eller flera strömslingor (4), fysiskt förenade med ett oscillationsorgan (5) i form av ett membran med en fjädrande fästanordning, i det visade exemplet utförd som en flexibel, ringformad del (6) utmed membranets periferi.With reference to Figure 1, and as partly described above, a magnetic system (2) movable about a central axis (1) is arranged. By rotational movement of the system, which comprises a plurality of magnets (3), (3 '), forming peripherally arranged poles, an electromotive force is induced in one or more current loops (4), physically connected to an oscillating means (5) in the form of a diaphragm with a resilient fastening device, in the example shown designed as a flexible, annular part (6) along the periphery of the diaphragm.

Oscillationsorganet bildar gränsyta till en tryckkammare (7), som mynnar i ett akustiskt horn eller en motsvarande impedanshöjande akustisk anordning.The oscillating means forms an interface to a pressure chamber (7), which opens into an acoustic horn or a corresponding impedance-increasing acoustic device.

Figur 2 visar en slinga som delvis befinner sig i ett passe- 5 rande magnetfält, såsom pilen visar. Därvid är slingans ' tvärgående del (8) i magnetfältet inducerande medan slingans längsgående del (9), som dock partiellt befinner sig utanför magnetfältet, kraftgenererande.Figure 2 shows a loop which is partly in a passing magnetic field, as the arrow shows. In this case, the transverse part (8) of the loop in the magnetic field is inducing, while the longitudinal part (9) of the loop, which is, however, partially outside the magnetic field, generates force.

Figur 3 visar, att som alternativ till slingans tvärgående delar enbart för induktion, en sneddad del (10) kan fungera såväl för induktion som för kraftgenerering. Härvid kan den sneddade ledaren till sin funktion betraktas som bestående 47u'¿7Ä av en längsgående (periferiell) del och en tvärgående (ax- iell) del. I denna figur visas för övrigt också_möjligheten att med olika magnetfältriktningar i två skilda magnetsek- tioner öka den inducerade elektromotoriska kraften och sam- tidigt under-passagen få en växlande kraftriktning.Figure 3 shows that as an alternative to the transverse parts of the loop only for induction, an inclined part (10) can function both for induction and for power generation. In this case, the inclined conductor can be regarded in its function as consisting of a longitudinal (peripheral) part and a transverse (axial) part. This figure also shows the possibility of increasing the induced electromotive force with different magnetic field directions in two different magnetic sections and at the same time obtaining an alternating force direction during the underpass.

Figur 4 visar en sekvens med två lägen av en förlängd slinga (11). Ett sådant utförande kan vara berättigat i avsikt att uppnå kompensation för en ofrånkomlig fasförskjutning mellan den elektromotoriska kraften och den inducerade strömmen.Figure 4 shows a sequence with two positions of an extended loop (11). Such an embodiment may be justified in order to obtain compensation for an unavoidable phase shift between the electromotive force and the induced current.

Det kan vara lämpligt att låta magnetfältet vid sin passage av slingan ha en förlängd verkningssträcka, för att kraften - i fas med strömmen - skall hinna verka.It may be appropriate to allow the magnetic field during its passage of the loop to have an extended range of action, so that the force - in phase with the current - has time to act.

De på oscillationsorganet verkande elektrodynamiska krafter- na på olika delar av en elektrisk slinga är i varje ögon- blick beroende av strömstyrkan och strömriktningen såväl som av ledarens riktning i förhållande till magnetfältets rikt- ning, och därutöver av den magnetiska flödestätheten. Efter- som en elektrodynamisk kraft fysikaliskt verkar vinkelrätt mot såväl ledarens riktning som magnetfältets riktning, kom- mer de krafter som kan utnyttjas för en axiell rörelse hos oscillationsorganet att utgöras endast av komposanter i de periferiellt längsgående delarna av ledaren. För önskad oscillation skall alltså dels - när viss del av slingan pas- seras av magnetfältlinjer med riktning tvärs desamma, gg elektromotorisk kraft induceras, och dels - när viss del av slingan passeras av ett magnetfält utan att skära fältlin- jerna, d v s periferiellt, en axialkraft genereras. Dessa krav innebär för den praktiska tillämpningen i föreliggande uppfinning, att en slingas ledare icke i sin helhet utan en- dast till vissa delar kan utnyttjas genom placering i mag- netfält. Üscillationen kan, såsom framgått av det föregående, genere- ras genom en serie kraftimpulser enbart i en och samma rikt- ning, förutsatt att oscillationsorganet har en härför lämpad fjädrande anordning (b). I princip kan en sådan fjäderanord- ning som den visade ersättas av exempelvis inbördes påver- kande magneter, attraherande eller repellerande.The electrodynamic forces acting on the oscillating means on different parts of an electric loop are at any moment dependent on the current and the direction of the current as well as on the direction of the conductor in relation to the direction of the magnetic field, and in addition on the magnetic flux density. Since an electrodynamic force physically acts perpendicular to both the direction of the conductor and the direction of the magnetic field, the forces which can be used for an axial movement of the oscillating means will consist only of components in the peripherally longitudinal parts of the conductor. For the desired oscillation, therefore - when a certain part of the loop is passed by magnetic field lines with direction across them, an electromotive force is induced, and partly - when a certain part of the loop is passed by a magnetic field without cutting the field lines, ie peripherally, a axial force is generated. These requirements mean for the practical application of the present invention that the conductor of a loop can not be used in its entirety but only to certain parts by placement in magnetic fields. As mentioned above, the oscillation can be generated by a series of force pulses in one and the same direction only, provided that the oscillation means has a resilient device (b) suitable for this purpose. In principle, such a spring device as the one shown can be replaced by, for example, mutually acting magnets, attracting or repelling.

Eftersom styrkan eller annorlunda uttryckt ljudtrycksnivån hos den akustiska tryckvåg som genereras primärt är beroende av svängningsamplituden hos oscillationsorganet, vill man generellt utnyttja möjligheterna till mekanisk resonans för detta. En sådan resonans innebär fysikaliskt, att masströg- hetens eljest reducerande inverkan på svängningen kan elimi- neras, vilket för tryckvågsgenereringen i dess helhet kan vara av stor betydelse. De optimala förutsättningarna för en effektiv alstring av en ljudvåg i fria luften råder först när oscillationsorganets egenfrekvens sammanfaller med fre- kvensen hos den styrande kraften, i detta fall den elektro- dynamiska. Men härvidlag är en viktig faktor dessutom, att anpassning i görligaste mån råder mellan å ena sidan impe- dansen hos den akustiska tryckvåg som belastar oscillations- organet utifrån och å andra sidan den inre impedans som betingas av organets egna parametrar, nämligen massa, elas- ticitet och påtryckta krafter. I de fall akustiskt horn ut- nyttjas för anpassning utåt, bör alltså den akustiska reso- 4 4-70 471 nansen i hornet liksom den tidigare nämnda inre egenresonan- sen överensstämma relativt väl med den frekvens som skall genereras.Since the strength or otherwise expressed the sound pressure level of the acoustic pressure wave generated is primarily dependent on the oscillation amplitude of the oscillating means, it is generally desired to use the possibilities of mechanical resonance for this. Such a resonance physically means that the otherwise reducing effect of mass inertia on the oscillation can be eliminated, which can be of great importance for the pressure wave generation as a whole. The optimal conditions for an efficient generation of a sound wave in the open air only prevail when the natural frequency of the oscillation means coincides with the frequency of the controlling force, in this case the electrodynamic one. But in this respect an important factor is also that adjustment takes place as far as possible between, on the one hand, the impedance of the acoustic pressure wave which loads the oscillating means from the outside and, on the other hand, the internal impedance which is conditioned by the means's own parameters. ticity and applied forces. In cases where acoustic horn is used for external adaptation, the acoustic resonance in the horn as well as the previously mentioned internal self-resonance should therefore correspond relatively well with the frequency to be generated.

Ett tänkbart alternativt sätt att inducera krafter av väx- lande axiell riktning på oscillationsorganet är att låta det vridbara magnetsystemet vara anordnat för torsionspendling kring ett bestämt medelläge. Metoden kan komma till använd- ning i vissa fall, när det exempelvis är praktiskt att med hjälp av ett fluidum åstadkomma en pendelrörelse i stället för en ren rotationsrörelse.A possible alternative way of inducing forces of varying axial direction on the oscillation means is to allow the rotatable magnet system to be arranged for torsional oscillation around a certain average position. The method can be used in certain cases, when it is practical, for example, to create a pendulum movement with the aid of a fluid instead of a pure rotational movement.

Modifieringar till de visade anordningarna vid den magneti- ska induktionsgeneratorn kan exemplifieras av följande: - Dscillationsorganet kan utföras som en kolv, således utan den periferiella infästning som visats i form av en fjädran- de del av organet. Ett sådant alternativt utförande förut- sätter en tätning med låg friktion utefter organets perife- ri. Vid behov av stor amplitud, motsvarande extremt höga akustiska effekter, kan detta utförande komma ifråga.Modifications to the devices shown at the magnetic induction generator can be exemplified by the following: The scaling means can be designed as a piston, thus without the peripheral attachment shown in the form of a resilient part of the means. Such an alternative design presupposes a seal with low friction along the periphery of the organ. If a large amplitude is required, corresponding to extremely high acoustic effects, this design can be considered.

- Den slinga eller de separata slingor, som är anordnade på oscillationsorganet för att försätta detta i rörelse, kan vardera bestå av ett flertal lindningsvarv, i fall då detta befinnes vara en konstruktionsteknisk fördel.The loop or the separate loops, which are arranged on the oscillation means for setting it in motion, can each consist of a plurality of winding turns, in cases where this is found to be a constructional technical advantage.

- Generatorns roterande magnetsystem kan, i stället för att drivas av en separat motor, sammanbyggas med en drivanord- ning i form av en trefaslindning med synkron eller asynkron .verkan på särskilda magnetelement respektive kortslutna slingor, applicerade på det roterande systemet. v, å I or*The generator's rotating magnetic system can, instead of being driven by a separate motor, be assembled with a drive device in the form of a three-phase winding with synchronous or asynchronous action on special magnetic elements and short-circuited loops, respectively, applied to the rotating system. v, å I or *

Claims

5 g 470171 'PATENT CLAIMS

Generator for acoustic pressure waves of audible frequency or inaudible frequency within the infrasound range, comprising a magnetic system (2) rotatable or rotatable about an axis (1), which by the movement of the system causes periodic movement of an oscillating means (5), arranged for pressure wave generation by setting the means in oscillation, characterized in that at least one closed current loop (4) is connected to the oscillation means and that the magnets (3), (3 ') in the rotatable or rotatable magnet system are arranged to form magnetic force fields within arranged sections of a path circular around the axis for induction of current in the loop and consequent electrodynamic forces which cause the said oscillation of the oscillating means during the movement of the magnetic system.

Generator according to claim 1, characterized in that the circular path is arranged as a slot included in the magnetic system with a circular shell-shaped extent and with the cross section as a gap space, arranged to be preferably radially crossed by magnetic lines of force. with different field direction and / or strength within separate sections of the circular path.

Generator according to claim 2, characterized in that a part of the oscillation means is designed as a cylindrical jacket and arranged to be able to move coaxially with respect to the circularly constructed magnetic system, when forces due to magnetic induction affect parts of the the current loop is mounted on the cylindrical jacket. 470 471

4. A generator according to any one of claims 1-3, characterized in that several separate current loops or sections of a single current loop in number and distribution correspond to the number and distribution of magnetic poles in the rotatable or rotatable system in such a way that identical current loops or sections of a current loop shall be simultaneously affected by magnetic fluxes with in relation to the conduction direction of the loops both transverse and longitudinal x motion.

Generator according to any one of claims 1-3, characterized in that several separate current loops or sections of a single current loop in number and distribution correspond to the number and distribution of magnetic poles in the rotatable or rotatable system in such a way that a part of a current loop (8) with respect to its conduction direction is transversely passed by a first magnetic flux, whereby current is induced, while another part of the current loop (9) with substantially non-transverse relative motion is passed by an adjacent second magnetic flux, forces being generated in the oscillation means axial direction.

Generator according to one of Claims 1 to 5, characterized in that the oscillation means is flexibly connected to the fixed part of the generator by means of such a device (6) that the oscillation movement in amplitude and phase is determined by the mass of the oscillation means and the directional forces of the resilient device connected to the fixed part of the generator, partly the electrodynamic forces and finally finally the acoustic forces from the opening of the generator towards the surroundings.

7. A generator according to any one of claims 1-6, characterized in that the oscillating means is flexibly connected to the fixed part of the generator in such a way that the mechanical natural frequency of the means either coincides with the acoustic resonant frequency of a pressure chamber (7) adjacent to the oscillation means in acoustic cooperation with an acoustic horn (12) or at least 1/3 octave from said acoustic resonant frequency.

B. A generator according to any one of claims 1-7, characterized in that a mechanical, hydraulic, pneumatic or electrically driven device is connected to the magnetic system to provide it with a reciprocating torsional oscillation centered about the axis of the system. .

9. A generator according to claim 8, characterized in that the torsional oscillation takes place at a frequency which is not more than 1/3 octave from the resonant frequency of the acoustic space arranged between the oscillating means and the external environment.