EP0586831B1 - Sound absorption method for motor vehicles - Google Patents
Sound absorption method for motor vehicles Download PDFInfo
- Publication number
- EP0586831B1 EP0586831B1 EP93111202A EP93111202A EP0586831B1 EP 0586831 B1 EP0586831 B1 EP 0586831B1 EP 93111202 A EP93111202 A EP 93111202A EP 93111202 A EP93111202 A EP 93111202A EP 0586831 B1 EP0586831 B1 EP 0586831B1
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- EP
- European Patent Office
- Prior art keywords
- hollow body
- helmholtz resonator
- loudspeaker
- noise
- helmholtz
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Classifications
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/30—Means
- G10K2210/321—Physical
- G10K2210/3227—Resonators
- G10K2210/32272—Helmholtz resonators
Definitions
- the invention relates to a sound absorption method for motor vehicles according to the preamble of the claim 1.
- DE 37 29 765 A1 describes a sound absorption process known in which several Helmholtz resonators, especially for low-frequency attenuation Cavity vibrations, connected in parallel and space-saving are housed in the vehicle body. At damping of sound pressure vibrations by Helmholtz resonators are in with lower frequencies usually larger hollow body volumes of the Helmholtz resonators required. That known from DE 37 29 765 A1 Sound absorption system tries the problem of large hollow body volumes only by the type of To solve accommodation in the motor vehicle.
- the hollow body volume of a Helmholtz resonator works in the form of the prevailing sound pressure behavior on sound absorption.
- the invention lies the thought is based in a relatively small Hollow body of a Helmholtz resonator has a sound pressure behavior to generate that the sound pressure behavior of the usual each necessary volume for the desired resonance frequency of the Helmholtz resonator, where the sound pressure is at least predominantly Dimensions is absorbed corresponds.
- a loudspeaker attached through which the hollow body is exposed to sound is that the volume of hollow body required for the desired resonance frequency in the hollow body is faked. Only a single hollow body volume can be used as well as sequentially or simulates several hollow body volumes simultaneously will. The simulation is particularly advantageous many hollow body volumes that a broadband resonance behavior in the form of an acoustic bandpass filter is produced.
- this invention provides sound absorption through Helmholtz resonators with a relative small volume possible.
- Helmholtz resonator both consecutively in time as well as being tuned to several resonance frequencies at the same time will.
- the following is the invention with a loudspeaker sounded Helmholtz resonator also as active Helmholtz resonator, while conventional Helmholtz resonators with specified real volumes passive Helmholtz resonators are also called.
- the loudspeaker is controlled by a Transmission system that takes place between those in the area prevailing sound pressure recording microphone and the one in the active Helmholtz resonator Speaker is arranged.
- the transmission system is designed such that the sound absorption system consisting of the microphone, the transmission system and the same transmission behavior to the active Helmholtz resonator has like a passive Helmholtz resonator that required for the desired resonance frequency real volume.
- the transmission system is, for example, by the structure an electrical switching arrangement with digital or analogous means realizable on the desired acoustic transmission behavior through electrical analogies is tunable.
- This passive comparison Helmholtz resonator is also matched to the absorption of the sound pressure at the desired resonance frequency.
- Such an electro-acoustic device is easier to set up and adapts to interference in the form of superimposed external pressure fluctuations better than an electrical switching arrangement based on an electrical analogy to an idealized acoustic arrangement.
- Fig. 1 On the left in Fig. 1 is the section in side view consisting of a conventional Helmholtz resonator of a hollow body with the volume V and an air passage opening with a neck of length 1 and Diameter d shown. On the right side of the Fig. 1 is the top view of the Helmholtz resonator with the air passage opening of the cross-sectional area a is shown.
- f C. 2 ⁇ * ( a l * V ) 1 ⁇ 2 with the speed of sound c, with the neck length l and the cross-sectional area a of the air passage opening and with the volume V of the hollow body.
- the dependence of the resonance frequency f solely on the volume V will be discussed below.
- the length l and the cross-sectional area a of the air passage opening are constant.
- the volume V must increase as the frequencies f decrease. This connection creates the problem of the large space requirement when using a Helmholtz resonator in motor vehicles, since in particular the sound pressure at low frequencies must be absorbed there.
- FIG. 2 presents two possible embodiments for an active Helmholtz resonator AHR1 and AHR2, the real volumes of which are each determined by the hollow body H.
- the air passage openings D are also firmly defined.
- the wall of the hollow body H opposite the air passage opening D is replaced by a loudspeaker L.
- the sound pressure values in the hollow body H are changed by the loudspeaker L, so that other imaginary volumes in the hollow body H are simulated than the volume that is actually present.
- the loudspeaker L fulfills the same function inside the hollow body H of the active Helmholtz resonator AHR2 is arranged. With this arrangement option the loudspeaker L is not part of a hollow body wall, but is at least almost complete in the hollow body H. sealed to the environment. Such an arrangement is needed, for example, when special measures against unwanted interference caused by overlapping Pressure fluctuations from outside the hollow body H should be taken.
- a microphone M is outside the active Helmholtz resonator AHR via an input line with a Transmission system Ü connected.
- the transmission system Ü is via an output line on the loudspeaker L of the active Helmholtz resonators AHR connected.
- the microphone M picks up the sound pressure values p a prevailing outside the hollow body H and converts them into a corresponding electrical signal which is passed on to the transmission system Ü.
- the transmission system Ü is an electronic switching arrangement with PD 2 T 2 transmission behavior.
- the loudspeaker L is driven by the electrical current I from the transmission system Ü.
- the transmission system U shown in FIG. 3 can be used for any number of resonance frequencies. In a further embodiment of the invention, it can accordingly also be used simultaneously for a large number of different desired resonance frequencies, the sound pressures of which are to be absorbed. For example, for a number n of desired resonance frequencies, the transmission system can be represented mathematically as follows:
- FIG. 4 shows an active Helmholtz resonator AHR and a passive comparative Helmholtz resonator PHR.
- a microphone M 1 outside the two Helmholtz resonators and a microphone M 2 inside the passive comparison Helmholtz resonator PHR are connected to a computing unit R via input lines.
- An output line of the computing unit R is connected to the loudspeaker L of the active Helmholtz resonator AHR.
- the passive comparative Helmholtz resonator PHR should be designed in miniature design at the same resonance frequency or for absorption of the sound pressure of the same frequency that is also to be absorbed by the active Helmholtz resonator AHR.
- the passive comparative Helmholtz resonator PHR has the same transmission behavior, which is also the basis for a passive Helmholtz resonator with the real hollow body volume, which corresponds to the hollow body volume required to be simulated for the sound pressure to be absorbed at the desired resonance frequency.
- the microphone M 1 records the sound pressure values outside the two Helmholtz resonators AHR and PHR in the vicinity of their air passage openings D1 and D2.
- the microphone M 2 detects the sound pressure values within the passive Helmholtz resonator PHR.
- the signals from the microphones M 1 and M 2 are fed to the computing unit R.
- the only difference between the two Helmholtz resonators AHR and PHR is that due to the differences in the volume of the hollow body, the active Helmholtz resonator AHR absorbs a sound energy many times greater than the passive comparison Helmholtz resonator PHR with the same frequency and damping. This absorption amplification takes place in the computing unit R and has an effect on the active Helmholtz resonator AHR by activating the loudspeaker L via the output line of the computing unit R.
- FIG. 1 The embodiment of the invention according to FIG.
- the invention can be applied to Helmholtz resonators with hollow bodies of any shape and air passage openings of any shape.
- an air passage opening in the form of a large-area sieve-like cover of the hollow body has proven to be particularly advantageous.
- An arrangement of several loudspeakers within the active Helmholtz resonator is also conceivable.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Description
Die Erfindung bezieht sich auf ein Schallabsorptionsverfahren für Kraftfahrzeuge nach dem Oberbegriff des Patentanspruchs 1.The invention relates to a sound absorption method for motor vehicles according to the preamble of the claim 1.
Ein derartiges Schallabsorptionsverfahren ist beispielsweise aus der US 5,119,427 bekannt. Bei diesem bekannten Verfahren wird jedoch offen gelassen, auf welche Weise ein zu simulierender Helmholtz-Resonator konkret nachgebildet werden soll.Such a sound absorption method is, for example known from US 5,119,427. In this well-known However, proceedings are left open in which way specifically simulated a Helmholtz resonator to be simulated shall be.
Aus der DE 37 29 765 A1 ist beispielsweise ein Schallabsorptionsverfahren bekannt, bei dem mehrere Helmholtz-Resonatoren, insbesondere zur Dämpfung tieffrequenter Hohlraumschwingungen, parallel geschaltet und platzsparend in der Fahrzeugkarosserie untergebracht sind. Bei einer Dämpfung von Schalldruckschwingungen durch Helmholtz-Resonatoren sind mit tiefer werdenden Frequenzen in der Regel größere Hohlkörpervolumina der Helmholtz-Resonatoren erforderlich. Das aus der DE 37 29 765 A1 bekannte Schallabsorptionssystem versucht das Problem der großen Hohlkörpervolumina lediglich durch die Art der Unterbringung im Kraftfahrzeug zu lösen.DE 37 29 765 A1, for example, describes a sound absorption process known in which several Helmholtz resonators, especially for low-frequency attenuation Cavity vibrations, connected in parallel and space-saving are housed in the vehicle body. At damping of sound pressure vibrations by Helmholtz resonators are in with lower frequencies usually larger hollow body volumes of the Helmholtz resonators required. That known from DE 37 29 765 A1 Sound absorption system tries the problem of large hollow body volumes only by the type of To solve accommodation in the motor vehicle.
Es ist Aufgabe der Erfindung,ein Schallabsorptionssystem zu schaffen, das bei Einsatz von Helmholtz-Resonatoren auch zur Absorption von tieffrequenten Schalldruckschwingungen keine großen Hohlkörpervolumina benötigt.It is an object of the invention to provide a sound absorption system to create that when using Helmholtz resonators also for the absorption of low-frequency sound pressure vibrations no large hollow body volumes required.
Diese Aufgabe wird durch die Merkmale des Patentanspruchs 1 gelöst.This object is achieved through the features of the patent claim 1 solved.
Vorteilhafte Weiterbildungen der Erfindung sind in den Unteransprüchen angegeben. Advantageous developments of the invention are specified in the subclaims.
Das Hohlkörpervolumen eines Helmholtz-Resonators wirkt sich in Form des in ihm vorherrschenden Schalldruckverhaltens auf die Schallabsorption aus. Der Erfindung liegt der Gedanke zugrunde, in einem verhältnismäßig kleinen Hohlkörper eines Helmholtz-Resonators ein Schalldruckverhalten zu erzeugen, das dem Schalldruckverhalten des üblicherweise jeweils notwendigen Hohlkörpervolumens für die jeweils gewünschte Resonanzfrequenz des Helmholtz-Resonators, bei der der Schalldruck zumindest in überwiegendem Maße absorbiert wird, entspricht. Dazu ist im Hohlkörper eines Helmholtz-Resonators ein Lautsprecher angebracht, durch den der Hohlkörper derart beschallt wird, daß das jeweils erforderliche Hohlkörpervolumen für die jeweils gewünschte Resonanzfrequenz im Hohlkörper vorgetäuscht wird. Dabei kann nur ein einziges Hohlkörpervolumen sowie aber auch zeitlich aufeinanderfolgend oder gleichzeitig mehrere Hohlköpervolumina simuliert werden. Besonders vorteilhaft ist die Simulation derart vieler Hohlkörpervolumina, daß ein breitbandiges Resonanzverhalten in Form eines akustischen Bandpaßfilters erzeugt wird.The hollow body volume of a Helmholtz resonator works in the form of the prevailing sound pressure behavior on sound absorption. The invention lies the thought is based in a relatively small Hollow body of a Helmholtz resonator has a sound pressure behavior to generate that the sound pressure behavior of the usual each necessary volume for the desired resonance frequency of the Helmholtz resonator, where the sound pressure is at least predominantly Dimensions is absorbed corresponds. This is in Hollow body of a Helmholtz resonator a loudspeaker attached through which the hollow body is exposed to sound is that the volume of hollow body required for the desired resonance frequency in the hollow body is faked. Only a single hollow body volume can be used as well as sequentially or simulates several hollow body volumes simultaneously will. The simulation is particularly advantageous many hollow body volumes that a broadband resonance behavior in the form of an acoustic bandpass filter is produced.
Durch diese Erfindung ist zum einen eine Schallabsorption durch Helmholtz-Resonatoren mit einem verhältnismäßig kleinen Volumen möglich. Zum anderen kann ein einziger Helmholtz-Resonator sowohl zeitlich aufeinanderfolgend als auch gleichzeitig auf mehrere Resonanzfrequenzen abgestimmt werden.On the one hand, this invention provides sound absorption through Helmholtz resonators with a relative small volume possible. On the other hand, one can Helmholtz resonator both consecutively in time as well as being tuned to several resonance frequencies at the same time will.
Im folgenden wird der erfindungsgemäß mit einem Lautsprecher beschallte Helmholtz-Resonator auch als aktiver Helmholtz-Resonator bezeichnet, während herkömmliche Helmholtz-Resonatoren mit vorgegebenen realen Volumina auch passive Helmholtz-Resonatoren genannt werden. The following is the invention with a loudspeaker sounded Helmholtz resonator also as active Helmholtz resonator, while conventional Helmholtz resonators with specified real volumes passive Helmholtz resonators are also called.
Durch das erfindungsgemäße Verfahren wird eine von den aktuellen in der Umgebung des aktiven Helmholtz-Resonators vorherrschenden Schalldruckwerten abhängige Ansteuerung des Lautsprechers erreicht. Die Ansteuerung des Lautsprechers findet durch ein Übertragungssystem statt, das zwischen dem die in der Umgebung vorherrschenden Schalldruckwerte aufnehmenden Mikrofon und dem im aktiven Helmholtz-Resonator befindlichen Lautsprecher angeordnet ist. Das Übertragungssystem ist derart ausgebildet, daß das Schallabsorptionssystem bestehend aus dem Mikrofon, dem Übertragungssystem und dem aktiven Helmholtz-Resonator dasselbe Übertragungsverhalten aufweist wie ein passiver Helmholtz-Resonator mit dem für die jeweils gewünschte Resonanzfrequenz erforderlichen realen Volumen.By the method according to the invention one of the current ones in the area of the active Helmholtz resonators prevailing sound pressure values dependent control of the speaker reached. The loudspeaker is controlled by a Transmission system that takes place between those in the area prevailing sound pressure recording microphone and the one in the active Helmholtz resonator Speaker is arranged. The transmission system is designed such that the sound absorption system consisting of the microphone, the transmission system and the same transmission behavior to the active Helmholtz resonator has like a passive Helmholtz resonator that required for the desired resonance frequency real volume.
Das Übertragungssystem ist beispielsweise durch den Aufbau einer elektrischen Schaltanordnung mit digitalen oder analogen Mitteln realisierbar, die auf das gewünschte akustische Übertragungsverhalten durch elektrische Analogien abstimmbar ist.The transmission system is, for example, by the structure an electrical switching arrangement with digital or analogous means realizable on the desired acoustic transmission behavior through electrical analogies is tunable.
Das Übertragungsverhalten des Übertragungssystems nach dem abhängigen Anspruch 2 bildet, insbesondere mit PD2T2-Gliedern, das Übertragungsverhalten eines passiven Helmholtz-Resonators mit einem realen, dem jeweils simulierten entsprechenden Volumen optimal nach.The transmission behavior of the transmission system according to the dependent claim 2, especially with PD 2 T 2 elements, optimally simulates the transmission behavior of a passive Helmholtz resonator with a real volume that is simulated in each case.
Mit der Vorrichtung nach dem abhängigen Anspruch 3 ist die Ansteuerung des Lautspreches zur Anpassung des aktiven Helmholtz-Resonators auf eine gewünschte Resonanzfrequenz mittels der gemessenen Schalldruckwerte innerhalb eines kleinen passiven Vergleichs-Helmholtz-Resonators möglich. With the device according to the dependent claim 3 is the control of the loudspeaker to adapt the active Helmholtz resonator to a desired resonance frequency by means of the measured sound pressure values within a small passive comparison Helmholtz resonators possible.
Das Übertragungsverhalten dieses passiven Vergleichs-Helmholtz-Resonators
ist ebenfalls auf die Absorption des
Schalldruckes bei der gewünschten Resonanzfrequenz abgestimmt.
Eine derartige elektro-akustische Vorrichtung ist einfacher
aufzubauen und paßt sich Störeinflüssen in Form von
sich überlagernden äußeren Druckschwankungen besser an
als eine elektrische Schaltanordnung auf der Basis einer
elektrischen Analogie zu einer idealisierten akustischen
Anordnung.The transmission behavior of this passive comparison Helmholtz resonator is also matched to the absorption of the sound pressure at the desired resonance frequency.
Such an electro-acoustic device is easier to set up and adapts to interference in the form of superimposed external pressure fluctuations better than an electrical switching arrangement based on an electrical analogy to an idealized acoustic arrangement.
In der Zeichnung sind Ausführungsbeispiele der Erfindung dargestellt. Es zeigen
- Fig. 1
- den schematischen Aufbau eines bekannten passiven Helmholtz-Resonators
- Fig. 2
- zwei mögliche Ausgestaltungen für einen aktiven Helmholtz-Resonator
- Fig. 3
- eine erfindungsgemäße Ansteuerung des Lautsprechers über ein elektronisch ausgebildetes Übertragungssystem und
- Fig. 4
- eine erfindungsgemäße Ansteuerung des Lautsprechers über ein elektro-akustisch ausgebildetes Übertragungssystem
- Fig. 1
- the schematic structure of a known passive Helmholtz resonator
- Fig. 2
- two possible configurations for an active Helmholtz resonator
- Fig. 3
- an inventive control of the speaker via an electronically trained transmission system and
- Fig. 4
- an inventive control of the speaker via an electro-acoustically designed transmission system
Gleiche Bauteile in den Figuren 1 bis 4 sind mit gleichen Bezugszeichen versehen.The same components in Figures 1 to 4 are the same Provide reference numerals.
Links in Fig. 1 ist in der Seitenansicht der Schnitt durch einen herkömmlichen Helmholtz-Resonator bestehend aus einem Hohlkörper mit dem Volumen V und einer Luftdurchtrittsöffnung mit einem Hals der Länge 1 und des Durchmessers d dargestellt. Auf der rechten Seite der Fig. 1 ist die Draufsicht des Helmholtz-Resonators mit der Luftdurchtrittsöffnung der Querschnittsfläche a gezeigt.On the left in Fig. 1 is the section in side view consisting of a conventional Helmholtz resonator of a hollow body with the volume V and an air passage opening with a neck of length 1 and Diameter d shown. On the right side of the Fig. 1 is the top view of the Helmholtz resonator with the air passage opening of the cross-sectional area a is shown.
Für die Resonanzfrequenz eines Helmholtz-Resonators, bei
der der Schalldruck zumindest in überwiegendem Maße absorbiert
wird, gilt die Beziehung:
Im folgenden soll auf die Abhängigkeit der Resonanzfrequenz
f allein vom Volumen V eingegangen werden. Die
Länge l und die Querschnittsfläche a der Luftdurchtrittsöffnung
seien konstant. Wie aus der Formel ersichtlich
ist, muß mit tiefer werdenden Frequenzen f das Volumen
V größer werden. Dieser Zusammenhang bildet die
Problematik des großen Platzbedarfs bei der Anwendung eines
Helmholtz-Resonators in Kraftfahrzeugen, da dort insbesondere
die Schalldrücke tiefer Frequenzen absorbiert
werden müssen.The following applies to the resonance frequency of a Helmholtz resonator, at which the sound pressure is at least predominantly absorbed:
The dependence of the resonance frequency f solely on the volume V will be discussed below. The length l and the cross-sectional area a of the air passage opening are constant. As can be seen from the formula, the volume V must increase as the frequencies f decrease. This connection creates the problem of the large space requirement when using a Helmholtz resonator in motor vehicles, since in particular the sound pressure at low frequencies must be absorbed there.
Fig. 2 stellt zwei mögliche Ausführungsformen für einen
aktiven Helmholtz-Resonator AHR1 und AHR2 vor, deren
reale Volumina jeweils durch den Hohlkörper H festgelegt
sind. Auch die Luftdurchtrittsöffnungen D seien jeweils
fest definiert.
Bei dem aktiven Helmholtz-Resonator AHR1 ist die der
Luftdurchtrittsöffnung D gegenüberliegende Wand des Hohlkörpers
H durch einen Lautsprecher L ersetzt. Durch den
Lautsprecher L werden die Schalldruckwerte im Hohlkörper
H verändert, so daß andere imaginäre Volumina im Hohlkörper
H simuliert werden als das Volumen, das real vorhanden
ist.2 presents two possible embodiments for an active Helmholtz resonator AHR1 and AHR2, the real volumes of which are each determined by the hollow body H. The air passage openings D are also firmly defined.
In the active Helmholtz resonator AHR1, the wall of the hollow body H opposite the air passage opening D is replaced by a loudspeaker L. The sound pressure values in the hollow body H are changed by the loudspeaker L, so that other imaginary volumes in the hollow body H are simulated than the volume that is actually present.
Dieselbe Funktion erfüllt auch der Lautsprecher L, der innerhalb des Hohlkörpers H des aktiven Helmholtz-Resonators AHR2 angeordnet ist. Bei dieser Anordnungsmöglichkeit ist der Lautsprecher L nicht Teil einer Hohlkörperwand, sondern ist im Hohlkörper H zumindest nahezu vollständig zur Umgebung hin abgedichtet. Eine derartige Anordnung wird beispielsweise benötigt, wenn besondere Maßnahmen gegen unerwünschte Störeinflüsse durch sich überlagernde Druckschwankungen von außerhalb des Hohlkörpers H ergriffen werden sollen.The loudspeaker L fulfills the same function inside the hollow body H of the active Helmholtz resonator AHR2 is arranged. With this arrangement option the loudspeaker L is not part of a hollow body wall, but is at least almost complete in the hollow body H. sealed to the environment. Such an arrangement is needed, for example, when special measures against unwanted interference caused by overlapping Pressure fluctuations from outside the hollow body H should be taken.
In Fig. 3 und 4 ist der Einfachheit halber jeweils nur ein aktiver Helmholtz-Resonator AHR in Form des Helmholtz-Resonators AHR1 dargestellt. Dies ist jedoch nicht einschränkend, sondern lediglich beispielhaft gemeint.3 and 4 is only for the sake of simplicity an active Helmholtz resonator AHR in the form of the Helmholtz resonator AHR1 shown. However, this is not restrictive, but only meant as an example.
In Fig. 3 ist ein Mikrofon M außerhalb des aktiven Helmholtz-Resonators AHR über eine Eingangsleitung mit einem Übertragungssystem Ü verbunden. Das Übertragungssystem Ü ist Über eine Ausgangsleitung am Lautsprecher L des aktiven Helmholtz-Resonators AHR angeschlossen.In Fig. 3, a microphone M is outside the active Helmholtz resonator AHR via an input line with a Transmission system Ü connected. The transmission system Ü is via an output line on the loudspeaker L of the active Helmholtz resonators AHR connected.
Das Mikrofon M nimmt in der Nähe der Luftdurchtrittsöffnung D des Hohlkörpers H die außerhalb des Hohlkörpers H vorherrschenden Schalldruckwerte pa auf und setzt diese in ein entsprechendes elektrisches Signal um, das an das übertragungssystem Ü weitergegeben wird. Das Übertragungssystem Ü sei eine elektronische Schaltanordnung mit PD2T2 Übertragungsverhalten. Der Lautsprecher L wird durch den elektrischen Strom I vom Übertragungsystem Ü angesteuert. In the vicinity of the air passage opening D of the hollow body H, the microphone M picks up the sound pressure values p a prevailing outside the hollow body H and converts them into a corresponding electrical signal which is passed on to the transmission system Ü. The transmission system Ü is an electronic switching arrangement with PD 2 T 2 transmission behavior. The loudspeaker L is driven by the electrical current I from the transmission system Ü.
Das PD2T2-Übertragungsverhalten kann beispielsweise für
eine einzige gewünschte Resonanzfrequenz mathematisch
durch folgende Formel entsprechend der Laplace-Transformation
Das in Fig. 3 dargestellte Übertragungssystem Ü ist für
beliebig viele Resonanzfrequenzen anwendbar. Es kann in
einer weiteren Ausgestaltung der Erfindung demnach auch
für eine Vielzahl verschiedener gewünschter Resonanzfrequenzen,
deren Schalldrücke zu absorbieren sind, gleichzeitig
angewendet werden.
Beispielsweise ist für eine Anzahl n von gewünschten Resonanzfrequenzen
das übertragungssystem mathematisch wie
folgt darstellbar:
For example, for a number n of desired resonance frequencies, the transmission system can be represented mathematically as follows:
Danach kann eine frequenzbreitbandige Wirksamkeit der Schalldruckabsorption erreicht werden, da sich der Helmholtz-Resonator gleichzeitig bei vielen Frequenzen in Eigenresonanz befindet. Then a broadband effectiveness of the Sound pressure absorption can be achieved because of the Helmholtz resonator at the same time at many frequencies in natural resonance located.
In Fig. 4 sind ein aktiver Helmholtz-Resonator AHR und ein passiver Vergleichs-Helmholtz-Resonator PHR dargestellt. Ein Mikrofon M1 außerhalb der beiden Helmholtz-Resonatoren und ein Mikrofon M2 innerhalb des passiven Vergleichs-Helmholtz-Resonators PHR sind über Eingangsleitungen mit einer Recheneinheit R verbunden. Eine Ausgangsleitung der Recheneinheit R ist am Lautsprecher L des aktiven Helmholtz-Resonators AHR angeschlossen.4 shows an active Helmholtz resonator AHR and a passive comparative Helmholtz resonator PHR. A microphone M 1 outside the two Helmholtz resonators and a microphone M 2 inside the passive comparison Helmholtz resonator PHR are connected to a computing unit R via input lines. An output line of the computing unit R is connected to the loudspeaker L of the active Helmholtz resonator AHR.
Der passive Vergleichs-Helmholtz-Resonator PHR soll in
Miniaturbauform auf dieselbe Resonanzfrequenz bzw. zur
Absorption des Schalldruckes derselben Frequenz ausgebildet
sein, der auch vom aktiven Helmholtz-Resonator AHR
absorbiert werden soll. Dazu besitzt der passive Vergleichs-Helmholtz-Resonator
PHR dasselbe Übertragungsverhalten,
das auch einem passiven Helmholtz-Resonator mit
dem realen Hohlköpervolumen, das dem für den zu absorbierenden
Schalldruck bei gewünschter Resonanzfrequenz erforderlichen
zu simulierenden Hohlköpervolumen entspricht,
zugrunde liegt.
Das Mikrofon M1 nimmt die Schalldruckwerte außerhalb der
beiden Helmholtz-Resonatoren AHR und PHR in der Nähe derer
Luftdurchtrittsöffnungen D1 und D2 auf. Das Mikrofon
M2 erfaßt die Schalldruckwerte innerhalb des passiven
Helmholtz-Resonators PHR. Die Signale der Mikrofone M1
und M2 werden der Recheneinheit R zugeführt. Die Recheneinheit
R ist kein frequenzabhängiges übertragungssystem
Ü (≠f(p), mit p=σ+jw), sondern lediglich eine additive
und/oder multiplikative Verstärkungsschaltung unter Berücksichtigung
der Konstanten C0, C1, C2, C3 und/oder C4,
die von der Form des Hohlkörpers H des AHR, von der gewünschten
Resonanzfrequenz f sowie vom Frequenz-Leistungs-Verlauf
des Lautsprechers L abhängen.
Die beiden Helmholtz-Resonatoren AHR und PHR unterscheiden
sich lediglich darin, daß aufgrund der Hohlkörpervolumenunterschiede
durch den aktiven Helmholtz-Resonator
AHR bei gleicher Freuqunz und gleicher Dämpfung eine um
ein Vielfaches größere Schallenergie absorbiert wird als
durch den passiven Vergleichs-Helmholtz-Resonator PHR.
Diese Absorptionsverstärkung findet in der Recheneinheit
R statt und wirkt sich über die Ansteuerung des Lautsprechers
L über die Ausgangsleitung der Recheneinheit R auf
den aktiven Helmholtz-Resonator AHR aus.
Auch die Ausgestaltung der Erfindung gemäß Fig. 4 ist auf
mehrere gewünschte Resonanzfrequenzen gleichzeitig anwendbar,
indem mehrere Vergleichs-Helmholtz-Resonatoren,
d.h. je ein jeder gewünschten Resonanzfrequenz zugeordneter
Vergleichs-Helmholtz-Resonator, in Parallelschaltung
zur Ansteuerung des Lautsprechers verwendet werden.The passive comparative Helmholtz resonator PHR should be designed in miniature design at the same resonance frequency or for absorption of the sound pressure of the same frequency that is also to be absorbed by the active Helmholtz resonator AHR. For this purpose, the passive comparative Helmholtz resonator PHR has the same transmission behavior, which is also the basis for a passive Helmholtz resonator with the real hollow body volume, which corresponds to the hollow body volume required to be simulated for the sound pressure to be absorbed at the desired resonance frequency.
The microphone M 1 records the sound pressure values outside the two Helmholtz resonators AHR and PHR in the vicinity of their air passage openings D1 and D2. The microphone M 2 detects the sound pressure values within the passive Helmholtz resonator PHR. The signals from the microphones M 1 and M 2 are fed to the computing unit R. The computing unit R is not a frequency-dependent transmission system Ü (≠ f (p), with p = σ + jw), but merely an additive and / or multiplicative amplification circuit, taking into account the constants C 0 , C 1 , C 2 , C 3 and / or C 4 , which depend on the shape of the hollow body H of the AHR, on the desired resonance frequency f and on the frequency-power curve of the loudspeaker L.
The only difference between the two Helmholtz resonators AHR and PHR is that due to the differences in the volume of the hollow body, the active Helmholtz resonator AHR absorbs a sound energy many times greater than the passive comparison Helmholtz resonator PHR with the same frequency and damping. This absorption amplification takes place in the computing unit R and has an effect on the active Helmholtz resonator AHR by activating the loudspeaker L via the output line of the computing unit R.
The embodiment of the invention according to FIG. 4 can also be applied to a plurality of desired resonance frequencies at the same time, in that a plurality of comparison Helmholtz resonators, that is to say a comparison Helmholtz resonator assigned to each desired resonance frequency, are used in parallel for driving the loudspeaker.
Darüber hinaus sei darauf hingewiesen, daß die Erfindung
auf Helmholtz-Resonatoren mit beliebig geformten Hohlkörpern
und beliebig ausgebildeten Luftdurchtrittsöffnungen
anwendbar ist. Beispielsweise hat sich eine Luftdurchtrittsöffnung
in Form einer größerflächigen siebartigen
Abdeckung des Hohlkörpers als besonders vorteilhaft erwiesen.
Auch ist eine Anordnung von mehreren Lautsprechern innerhalb
des aktiven Helmholtz-Resonators denkbar.In addition, it should be pointed out that the invention can be applied to Helmholtz resonators with hollow bodies of any shape and air passage openings of any shape. For example, an air passage opening in the form of a large-area sieve-like cover of the hollow body has proven to be particularly advantageous.
An arrangement of several loudspeakers within the active Helmholtz resonator is also conceivable.
Claims (3)
- A noise absorption method for motor vehicles, in which noise pressures are generated by means of a loudspeaker and in which by means of a Helmholtz resonator noise pressure at its resonant frequency is absorbed,
characterised in that, by means of the loudspeaker (L) positioned in the hollow body (H) of the Helmholtz resonator (AHR, AHR1, AHR2) noise pressures are generated in the hollow body (H), by which simultaneously or in time sequence, hollow body volumes, differing from the actual hollow body volume (H) are simulated, whereby the hollow body volumes to be simulated are determined, based on any desired resonant frequencies for the Helmholtz resonator (AHR, AHR1, AHR2), whereby by means of a first microphone (M, M1) the noise pressure values (pa) prevailing outside the Helmholtz resonator (AHR, AHR1, AHR2) are accepted and passed to a transmission system (Ü), by which the loudspeaker (L) is driven such that through the whole of the noise absorption method the transmission relationships of Helmholtz resonators with actual volumes are simulated by corresponding simulated volumes. - A noise absorption method according to claim 1, characterised in that to each of the desired resonant frequencies in the transmission system (Ü) a PDiTk element, with i and k greater than or equal to 1, advantageously 1 or 2, is allocated and that the transmission system (Ü) is created from the sum of all the PDiTk elements.
- A noise absorption method according to claim 1 or 2, characterised in that the loudspeaker (L) for the generation of desired resonant frequency by the simulation of the necessary hollow body volume for it is driven by means of the noise pressure signal from a further microphone (M2) within a reference Helmholtz resonator (PHR), constructed in miniature form, which has the same transmission characteristic referred to the desired resonant frequency as a Helmholtz resonator with an actual hollow body volume corresponding to the simulated hollow body volume.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4226885 | 1992-08-13 | ||
| DE4226885A DE4226885C2 (en) | 1992-08-13 | 1992-08-13 | Sound absorption process for motor vehicles |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0586831A2 EP0586831A2 (en) | 1994-03-16 |
| EP0586831A3 EP0586831A3 (en) | 1994-03-30 |
| EP0586831B1 true EP0586831B1 (en) | 1998-09-02 |
Family
ID=6465521
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP93111202A Expired - Lifetime EP0586831B1 (en) | 1992-08-13 | 1993-07-13 | Sound absorption method for motor vehicles |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0586831B1 (en) |
| DE (2) | DE4226885C2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004016689A1 (en) * | 2004-04-05 | 2005-10-27 | Volkswagen Ag | Improvement of acoustic situation in passenger cabin of vehicle, comprising use of Helmholtz-resonators |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4446080B4 (en) * | 1994-12-22 | 2004-03-18 | Bayerische Motoren Werke Ag | Sound absorption system for motor vehicles |
| EP0916817B1 (en) | 1997-11-18 | 2006-02-08 | Faurecia Abgastechnik GmbH | Active silencer |
| DE19861018C2 (en) | 1998-12-15 | 2001-06-13 | Fraunhofer Ges Forschung | Controlled acoustic waveguide for sound absorption |
| EP1085201B1 (en) * | 1999-09-16 | 2003-11-19 | Siemens VDO Automotive Inc. | Tuned active helmholtz resonator with forced response |
| GB2387522B (en) * | 2002-04-10 | 2005-09-28 | Hobelsberger Max | Tunable active sound absorbers |
| FR2899011B1 (en) * | 2006-03-24 | 2008-07-18 | Eurocopter France | METHOD AND DEVICE FOR PROCESSING NOISE ON BOARD AN AIRCRAFT |
| WO2013064602A1 (en) | 2011-11-04 | 2013-05-10 | Empa Eidgenössische Materialprüfungs- Und Forschungsanstalt | Adaptive helmholtz resonator |
| DE102017115271B4 (en) * | 2017-07-07 | 2019-04-18 | Tenneco Gmbh | Method for operating a motor vehicle noise suppression system |
| WO2019007700A1 (en) | 2017-07-07 | 2019-01-10 | Tenneco Gmbh | Noise cancellation system |
| CN111720189B (en) * | 2019-03-22 | 2024-01-23 | 广州汽车集团股份有限公司 | Exhaust system sound quality adjusting device and method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3412432A1 (en) * | 1984-04-03 | 1985-10-10 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München | Sound-absorbing building element |
| DE3720946A1 (en) * | 1986-07-03 | 1988-01-07 | Volkswagen Ag | Body platform for a motor vehicle |
| DE3729765A1 (en) * | 1987-09-05 | 1989-03-16 | Bayerische Motoren Werke Ag | Sound absorption system |
| US5119427A (en) * | 1988-03-14 | 1992-06-02 | Hersh Alan S | Extended frequency range Helmholtz resonators |
| DE3816921A1 (en) * | 1988-05-18 | 1989-11-30 | Bayerische Motoren Werke Ag | ARRANGEMENT FOR REDUCING NOISE LEVEL IN THE INTERIOR OF A MOTOR VEHICLE |
| DE4011705A1 (en) * | 1990-04-11 | 1991-10-17 | Freudenberg Carl Fa | AIR SOUND ABSORBING MOLDED PART |
| US5119902A (en) * | 1990-04-25 | 1992-06-09 | Ford Motor Company | Active muffler transducer arrangement |
| DE4027511C1 (en) * | 1990-08-30 | 1991-10-02 | Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V., 8000 Muenchen, De |
-
1992
- 1992-08-13 DE DE4226885A patent/DE4226885C2/en not_active Expired - Fee Related
-
1993
- 1993-07-13 EP EP93111202A patent/EP0586831B1/en not_active Expired - Lifetime
- 1993-07-13 DE DE59308951T patent/DE59308951D1/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004016689A1 (en) * | 2004-04-05 | 2005-10-27 | Volkswagen Ag | Improvement of acoustic situation in passenger cabin of vehicle, comprising use of Helmholtz-resonators |
Also Published As
| Publication number | Publication date |
|---|---|
| DE4226885A1 (en) | 1994-02-17 |
| DE4226885C2 (en) | 2001-04-19 |
| DE59308951D1 (en) | 1998-10-08 |
| EP0586831A3 (en) | 1994-03-30 |
| EP0586831A2 (en) | 1994-03-16 |
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