DK176324B1

DK176324B1 - Double sensor and method for measuring sound and vibration, as well as its use

Info

Publication number: DK176324B1
Application number: DK200600398A
Authority: DK
Inventors: Gunnar Rasmussen; Per Rasmussen
Original assignee: G R A S Sound & Vibration As
Priority date: 2006-03-21
Filing date: 2006-03-21
Publication date: 2007-08-06

Description

DK 176324 B1 iDK 176324 B1 i

Den foreliggende opfindelse angår sensorer til måling af lyd og vibration. Navnlig angår den foreliggende opfindelse en dobbelt sensor, til at måle både lyd og vibration, hvilken sensor omfatter et hus, i hvilket der befinder sig i det mindste én inertimasse af et accelerometer, og 5 i hvilket der befinder sig en akustisk tryktransducer.The present invention relates to sensors for measuring sound and vibration. In particular, the present invention relates to a dual sensor for measuring both sound and vibration, which sensor comprises a housing in which is located at least one inertial mass of an accelerometer and 5 in which is an acoustic pressure transducer.

Ved mange akustiske måleanvendelser er der et behov for at korrelere den akustiske måling med en accelerationsmåling. Dette er navnlig, men ikke udelukkende, tilfældet, når formålet med den akustiske måling er at tilpasse et givent miljø for at reducere det samlede 10 støjniveau i dette miljø. Et eksempel på sådan et miljø er passagerkabinen i et automobil. Automobilers passagerkabiner er iboende støjfyldte, når automobilet kører. Strukturblrne vibrationer fra motoren, transmissionen, hjulene, ophænget, vinduesviskere etc. kan forårsage trykæn-dringer i luften, der opfattes som lyd eller, i det omfang lydene ikke in-15 deholder nogen information, som støj, i passagerkabinen. Automobilin-dustrien bekymrer sig i almindelighed om lydene i passagerkabinen.In many acoustic measurement applications, there is a need to correlate the acoustic measurement with an acceleration measurement. This is particularly, but not exclusively, the case when the purpose of the acoustic measurement is to adapt a given environment to reduce the overall noise level in that environment. An example of such an environment is the passenger cabin of an automobile. Automobiles passenger cabins are inherently noisy when the vehicle is driving. Structural vibrations from the engine, transmission, wheels, suspension, windscreen wipers etc. can cause air pressure changes that are perceived as sound or, to the extent that the sounds do not contain any information, such as noise, in the passenger compartment. The automobile industry generally cares about the sounds in the passenger compartment.

Med få undtagelser skal den støj, som forårsages af automobilet selv, i almindelighed reduceres mest muligt. En sådan undtagelse er interessen hos føreren af et automobil med manuel transmission i at høre motoren 20 for at vurdere, hvornår der skal skiftes gear.With few exceptions, the noise caused by the car itself should generally be minimized as much as possible. One such exception is the interest of the driver of a manual transmission automobile in hearing the engine 20 to assess when to change gears.

En typisk tilgang til at reducere støjniveauet er at dæmpe dele, såsom paneler, der kan gå i resonans ved visse frekvenser, og således udsende lyd. Det er dog ikke klart, at et hvilket som helst vibrerende panel er i resonans og afgiver lyd, det kan lige så vel være, at vibratio-25 nen optræder under indflydelse af lyde, og således faktisk absorberer lyd i stedet for at forårsage den. Det kan også være, at panelet overhovedet ikke er påvirket af lyden. En mikrofon, der er placeret på eksempelvis et panel, giver således ikke nogen information om, hvorvidt panelet i sig selv bidrager til lyden i passagerkabinen.A typical approach to reducing the noise level is to attenuate parts, such as panels that can resonate at certain frequencies, and thus emit sound. However, it is not clear that any vibrating panel is in resonance and emits sound, it may as well be that the vibration occurs under the influence of sounds, and thus actually absorbs sound instead of causing it. It may also be that the panel is not affected at all by the sound. Thus, a microphone located on, for example, a panel, does not provide any information as to whether the panel itself contributes to the sound in the passenger compartment.

30 Tilgangen til de akustiske målinger har hidtil været at placere både accelerometre og mikrofoner på de relevante dele, for derved at måle, hvordan delen vibrerer, og at korrelere denne vibration med det lydtryk, der måles af mikrofonerne.The approach to the acoustic measurements has so far been to place both accelerometers and microphones on the relevant parts, thus measuring how the part vibrates and to correlate this vibration with the sound pressure measured by the microphones.

Denne tilgang er imidlertid ikke ideel, fordi der for præcis må- DK 176324 B1 2 ling skal være rumlig korrelation mellem de to målinger, dvs. at accelerationen ideelt set skulle måles pi præcis det samme sted i rummet som lydtrykket.However, this approach is not ideal because for precise measurement there must be spatial correlation between the two measurements, ie. that the acceleration should ideally be measured in exactly the same place in the room as the sound pressure.

Ifølge et første aspekt af opfindelsen overvindes det ovennævn-5 te problem ved at tilvejebringe en dobbelt sensor til måling af lyd og vibration, hvilken sensor omfatter et hus, i hvilket der befinder sig i det mindst én inertimasse af et accelerometer samt en akustisk tryktransducer, hvor den i det mindste ene inertimasse er fordelt omkring en central akse af sensoren, for derved at tilvejebringe en massefordeling, 10 hvis massemidtpunkt er sammenfaldende med den centrale akse, og hvor den akustiske tryktransducer er placeret centralt, sammenfaldende med den centrale akse, hvilken sensor er ejendommelig ved, at den akustiske tryktransducer er placeret på den centrale akse på et sted, ^ som er i det mindste delvist sammenfaldende med den lodrette projek-15 tion af den i det mindste ene inertimasse på den centrale akse.According to a first aspect of the invention, the above problem is overcome by providing a dual sensor for measuring sound and vibration, comprising a housing in which is located at least one inertial mass of an accelerometer as well as an acoustic pressure transducer. wherein at least one inertial mass is distributed around a central axis of the sensor, thereby providing a mass distribution 10 whose center of mass is coincident with the central axis and the acoustic pressure transducer is located centrally, coinciding with the central axis, which sensor is characterized in that the acoustic pressure transducer is located on the central axis at a location which is at least partially coincident with the vertical projection of the at least one inertial mass on the central axis.

Ved denne indretning, hvor den seismiske masse eller masserne er placeret omkring den akustiske tryktransducer, er en præcis måling af lydtrykket og accelerationen i i det væsentlige et enkelt punkt mulig. Endvidere involverer dette kun placeringen af en enkelt sensor-20 enhed for hver måling af lyd og vibrationer i et givent punkt, når der skal sættes måleudrustning op.In this device, where the seismic mass or masses are located around the acoustic pressure transducer, an accurate measurement of the sound pressure and acceleration at essentially a single point is possible. Furthermore, this only involves the placement of a single sensor unit for each measurement of sound and vibration at a given point when measuring equipment is to be set up.

Hvad angår dobbelte sensorer til lyd og vibration, skal det bemærkes, at US-A-4928263 beskriver en accelerometerbaseret retningsbestemmelse og hydrofon, omfattende en piezoelektrisk akustisk sen-25 sor, der er placeret inden i huset, og adskillige piezoelektriske accele-rometre, der deler en seismisk masse, som befinder sig i huset. Denne hydrofon ville imidlertid ikke være egnet til de målinger, som den foreliggende opfindelse beskæftiger sig med.Regarding dual sensors for sound and vibration, it should be noted that US-A-4928263 discloses an accelerometer-based directional and hydrophone comprising an in-house piezoelectric acoustic sensor and several piezoelectric accelerometers which shares a seismic mass located in the housing. However, this hydrophone would not be suitable for the measurements of the present invention.

Ifølge en foretrukken udførelsesform omfatter den i det mindste 30 ene inertimasse et generelt ringformet legeme med en central åbning, hvor den akustiske tryktransducer befinder sig i denne centrale åbning.According to a preferred embodiment, the at least one inert mass comprises a generally annular body with a central aperture, wherein the acoustic pressure transducer is located in this central aperture.

Sådan et enkelt ringformet legeme, er ikke blot relativt enkelt at fremstille, men anvendelsen af blot sådan et enkelt ringformet legeme letter også samlingen og den præcise koaksiale opretning af delene.Such a single annular body is not only relatively simple to manufacture, but the use of just such a single annular body also facilitates the assembly and precise coaxial alignment of the parts.

DK 176324 B1 3DK 176324 B1 3

Sidstnævnte er navnlig tilfældet, når den akustiske tryktransducer ifølge en yderligere foretrukken udførelsesform finder plads i den centrale åbning og er i fast forbindelse med det ringformede legeme, således at den udgør en del af den i det mindste ene inertimasse.The latter is especially true when the acoustic pressure transducer according to a further preferred embodiment takes place in the central opening and is in fixed communication with the annular body, so that it forms part of the at least one inertial mass.

5 Ifølge en anden foretrukken udførelsesform har huset et gene relt cylindrisk indre hulrum med en bund og en sidevæg, og ved at inertimassen befinder sig på en sådan måde i hulrummet, at i det mindste ét piezoelektrisk element finder plads mellem periferien af den ringformede inertimasse og sidevæggen af hulrummet. Dette bidrager yderli-10 gere til præcisionen, fordi det ringformede legeme på denne måde kan placeres ganske præcist i forhold til huset. Det faktiske målepunkt er derfor ganske veldefineret, når hele den dobbelte sensor er placeret på et sted, hvor malingerne skal finde sted.According to another preferred embodiment, the housing has a generally cylindrical inner cavity having a bottom and a side wall, and in that the inertia mass is in such a way that at least one piezoelectric element takes place between the periphery of the annular inertia and the side wall of the cavity. This further adds to the precision because the annular body can thus be placed quite precisely in relation to the housing. The actual measurement point is therefore quite well defined when the entire dual sensor is located in a place where the paints are to take place.

Ifølge endnu en yderligere udførelsesform omfatter huset i det 15 mindste én plan ydre overflade. Dette hjælper til med placeringen af den dobbelte sensor på en overflade, hvor målingerne skal finde sted.According to yet another embodiment, the housing comprises at least one plane outer surface. This helps with the placement of the dual sensor on a surface where the measurements must take place.

Ifølge et andet aspekt af opfindelsen overvindes det ovennævnte problem ved en fremgangsmåde, ved hvilken målingerne udføres under brug af en dobbelt sensor ifølge det første aspekt.According to another aspect of the invention, the above problem is overcome by a method in which the measurements are performed using a dual sensor according to the first aspect.

20 Ifølge tredje aspekt af opfindelsen anvendes fremgangsmåden ifølge det andet aspekt af opfindelsen, som gør brug af den dobbelte sensor ifølge det første aspekt af opfindelsen, til at udføre målinger på et transportmiddel, fortrinsvis et automobil.According to the third aspect of the invention, the method according to the second aspect of the invention, which uses the dual sensor according to the first aspect of the invention, is used to perform measurements on a means of transport, preferably an automobile.

Opfindelsen vil nu blive beskrevet mere detaljeret på basis af 25 ikke-begrænsende eksempler på udførelsesformer af opfindelsen og under henvisning til tegningen. På tegningen viser, fig. 1 et endebillede af huset af den dobbelte sensor ifølge opfindelsen, fig. 2 et planbillede ovenfra af huset ifølge fig. 1, 30 fig. 3 et tværsnitsbillede af huset taget langs linjen A-A i fig. 1, og fig. 4 et tværsnitsbillede svarende til det i fig. 3, men med den akustiske transducer på plads, fig. 5 et tværsnitsbillede svarende til det i fig. 4, men uden en DK 176324 B1 4 mikrofonunderstøtning, og fig. 6 et tværsnitsbillede svarende til det i fig. 5, men med den akustiske tryktransducer placeret som en del af den seismiske masse.The invention will now be described in more detail on the basis of 25 non-limiting examples of embodiments of the invention and with reference to the drawings. In the drawing, FIG. 1 is an end view of the dual sensor housing according to the invention; FIG. 2 is a top plan view of the housing of FIG. 1, FIG. 3 is a cross-sectional view of the housing taken along line A-A of FIG. 1, and FIG. 4 is a cross-sectional view similar to that of FIG. 3 but with the acoustic transducer in place; FIG. 5 is a cross-sectional view similar to that of FIG. 4, but without a microphone support, and fig. 6 is a cross-sectional view similar to that of FIG. 5 but with the acoustic pressure transducer located as part of the seismic mass.

Der henvises først til fig. 1, som viser et endebillede af huset af 5 den dobbelte sensor ifølge opfindelsen. Huset omfatter en første, generel cylindrisk legemedel 1 og en lågdel 2. Både legemedelen 1 og lågdelen 2 er fortrinsvis lavet af metal såsom aluminium eller rustfrit stål.Referring first to FIG. 1, which shows an end view of the housing of the dual sensor according to the invention. The housing comprises a first general cylindrical body member 1 and a lid member 2. Both the body member 1 and the lid member 2 are preferably made of metal such as aluminum or stainless steel.

Den cylindriske legemedel 1 omfatter et fladt fremspring 3, som tilvejebringer en i det væsentlige plan bundoverflade, til at fastgøre huset til 10 overfladen af et objekt (ikke vist), såsom et panel et automobil, under måling. Fortrinsvis har huset et rør eller en gennemføring 4 til tilslutning af ledninger (ikke vist) til sensorerne i huset.The cylindrical body 1 comprises a flat projection 3 which provides a substantially flat bottom surface for attaching the housing to the surface of an object (not shown), such as a panel an automobile, during measurement. Preferably, the housing has a pipe or conduit 4 for connecting wires (not shown) to the sensors in the housing.

Idet der nu henvises til fig. 2, som viser et planbillede ovenfra af huset, kan det ses, at lågdelen 2 har en åbning 5. Som det vil blive 15 beskrevet efterfølgende under henvisning til fig. 4, tjener denne åbning 5 som en lydindgangsport for den akustiske tryktransducer 6. Gennem åbningen 5 kan der ses et spor 7 i den indvendige bund af legemedelen 1. Dette spor tjener som en forlængelse af gennemføringen for at tilvejebringe plads til tilslutningsledningerne.Referring now to FIG. 2, which shows a plan view from above of the housing, it can be seen that the lid part 2 has an opening 5. As will be described below with reference to FIG. 4, this opening 5 serves as a sound input port for the acoustic pressure transducer 6. Through the opening 5, a groove 7 can be seen in the inner bottom of the body member 1. This groove serves as an extension of the throughput to provide space for the connection lines.

20 Fig. 3 viser et tværsnit af huset taget langs linjen A-A i fig. 1.FIG. 3 is a cross-sectional view of the housing taken along line A-A of FIG. First

Her kan det ses, at legemedelen 1 af huset er generelt kopformet med et indre hulrum. I den foretrukne udføreisesform er det indre hulrum fortrinsvis cylindrisk. Ved bunden 8 af hulrummet er diameteren af det cylindriske hulrum reduceret og tilvejebringer således en rundtgående 25 afsats 9.Here it can be seen that the body part 1 of the housing is generally cup-shaped with an inner cavity. In the preferred embodiment, the inner cavity is preferably cylindrical. At the bottom 8 of the cavity, the diameter of the cylindrical cavity is reduced, thus providing a circumferential ledge 9.

Den rundtgående afsats 9 tjener som understøtning for et antal piezoelektriske blokke 10, af hvilke kun to er synlige i fig. 3. Det er klart, at afsatsen ikke behøver være rundtgående, men alene kunne være tilvejebragt dér, hvor der er behov for at understøtte de piezoe-30 iektriske blokke 10. Mellem de piezoelektriske blokke 10 befinder der sig et i det væsentlige ringformet legeme 11. Det ringformede legeme 11 er kun i kontakt med de piezoelektriske blokke 10 og hænger således ophængt fra disse, for derved at tilvejebringe vibrationssensorens seismiske masse. Det ringformede legeme 11 er fortrinsvis lavet af metal med DK 176324 B1 5 en høj densitet, såsom wolfram, for at forøge dets inerti. Når den dobbelte sensor ifølge opfindelsen bevæger sig, f.eks. fordi det er monteret på en vibrerende del af et automobil, vil inertimassen tendere til at forblive stationær, hvilket får husdelen 1 til at udøve en kraft pi de piezo-5 elektriske blokke. Under denne kraft tilvejebringer en piezoelektrisk blok en spænding, der repræsenterer kraften. Denne spænding kan via forbindelsesledninger (ikke vist), der er forbundet til de piezoelektriske blokke 10, måles af ekstern udrustning, som den dobbelt sensor er sluttet til. Fortrinsvis er der kun forbundet én ledning direkte til den piezoe-10 lektriske blok 10, idet metalhusdelen 1 udgør den anden forbindelse.The circumferential ledge 9 serves as a support for a number of piezoelectric blocks 10, only two of which are visible in FIG. 3. Obviously, the ledge need not be circumferential, but could only be provided where the piezoelectric blocks 10 are needed to be supported. Between the piezoelectric blocks 10 there is a substantially annular body 11. The annular body 11 is only in contact with the piezoelectric blocks 10 and thus hangs suspended therefrom, thereby providing the seismic mass of the vibration sensor. The annular body 11 is preferably made of metal with a high density, such as tungsten, to increase its inertia. As the dual sensor of the invention moves, e.g. because it is mounted on a vibrating part of an automobile, the inertia mass will tend to remain stationary, causing the housing part 1 to exert a force on the piezo-electric blocks. Under this force, a piezoelectric block provides a voltage representing the force. This voltage can be measured, via connecting wires (not shown) connected to the piezoelectric blocks 10, by external equipment to which the dual sensor is connected. Preferably, only one wire is connected directly to the piezoelectric block 10, the metal housing portion 1 constituting the other connection.

Det ringformede legeme 11 har en central åbning i form af en gennemgående boring. Den gennemgående boring har en første stor diameter og en anden mindre diameter, således at der er tilvejebragt en skulder 12. Som det kan ses i fig. 4 er den første, større diameter ind-15 rettet til at optage en akustisk tryktransducer 6 i det ringformede legeme 11, hvilken transducer understøttes i den aksiale retning af et understøtningsorgan 13. Understøtningsorganet 13 er lavet af et elektrisk isolerende materiale, såsom FTFE, og klæbet på den indre bund 8 af det cylindriske hus 1. Endvidere er understøtningsorganet forsynet med én 20 eller flere passager 14 for at tillade forbindelsesledninger at føre til de piezoelektriske blokke 10. I denne udførelsesform er den store diameter af boringen tilstrækkelig til at optage den akustiske tryktransducer 6 med tilstrækkelig frigang omkring sidstnævnte, således at der tillades bevægelse af det ringformede legeme, uden at det interfererer med den 25 akustiske tryktransducer 6.The annular body 11 has a central opening in the form of a through bore. The through bore has a first large diameter and a second smaller diameter, so that a shoulder 12 is provided. As can be seen in FIG. 4, the first larger diameter is arranged to receive an acoustic pressure transducer 6 in the annular body 11, which transducer is supported in the axial direction by a support member 13. The support member 13 is made of an electrically insulating material such as FTFE, and further, the support means is provided with one 20 or more passages 14 to allow connecting leads to the piezoelectric blocks 10. In this embodiment, the large diameter of the bore is sufficient to accommodate the acoustic pressure transducers 6 of sufficient clearance around the latter to allow movement of the annular body without interfering with the acoustic pressure transducer 6.

Den del af boringen, som har mindre diameter, tillader blandt andet adgang for elektriske ledninger til den akustiske tryktransducer 6 og de piezoelektriske blokke 10, sidstnævnte gennem en yderligere boring 15, der er placeret i den radiale retning i det ringformede legeme 30 11 mellem dettes ydre overflade og den del af boringen, som har den mindre diameter.The smaller diameter portion of the bore allows, inter alia, access to electrical wires to the acoustic pressure transducer 6 and the piezoelectric blocks 10, the latter through an additional bore 15 located in the radial direction in the annular body 30 11 between its outer surface and the portion of the bore having the smaller diameter.

Den akustiske tryktransducer 6 er fortrinsvis en forud samlet kondensatormikrofonenhed af kendt type. Kondensatormikrofonenheden har en generelt symmetrisk geometri omkring en central akse, som er DK 176324 B1 6 sammenfaldende med den centrale akse af huset 1. Den akustiske tryktransducer 6 har et cylindrisk mikrofonhus 16, i hvilken der befinder sig en understøtningsplade 17. Understøtningspladen 17 har en ledende frontoverflade 18, der er placeret parallelt med en ledende mikrofon-5 membran 19. Variationer i lufttrykket, såsom lyd, vil bevæge mikrofonmembranen i forhold til understøtningspladen, og således give anledning til en målbar ændring i kapacitansen mellem frontoverfladen 18 af understøtningspladen 17 og membranen 19.The acoustic pressure transducer 6 is preferably a pre-assembled condenser microphone unit of known type. The condenser microphone unit has a generally symmetrical geometry about a central axis which coincides with the central axis of the housing 1. The acoustic pressure transducer 6 has a cylindrical microphone housing 16 in which is a support plate 17. The support plate 17 has a conductive front surface 18 located parallel to a conductive microphone membrane 19. Variations in air pressure, such as sound, will move the microphone membrane relative to the support plate, thus giving rise to a measurable change in the capacitance between the front surface 18 of the support plate 17 and the membrane 19 .

Med den akustiske tryktransducer 6 placeret i den centrale bo-10 ring af det ringformede legeme 11, falder massemidtpunktet af massedistributionen af inertimassen, dvs. det ringformede legeme 11, sammen med den centrale akse af den akustiske tryktransducer 6. Den akustiske måling finder endvidere sted meget tæt på massemidtpunktet af massefordelingen, fordi den akustiske tryktransducer befinder sig mere 15 eller mindre omgivet af inertimassen, hvilket tillader lyd og vibration at blive målt i, hvad der for alle praktiske formål kan ses for at være et enkelt punkt.With the acoustic pressure transducer 6 located in the central bore of the annular body 11, the mass center of mass distribution of the inert mass decreases, i.e. the annular body 11, together with the central axis of the acoustic pressure transducer 6. Furthermore, the acoustic measurement takes place very close to the mass center of the mass distribution because the acoustic pressure transducer is more or less surrounded by the inert mass, allowing sound and vibration to be measured in what for all practical purposes can be seen to be a single point.

Lagdelen 2 er fortrinsvis presset på husdelen 1 og fastholdt dér af friktion alene, men dette er ikke vigtigt for opfindelsen. Fagmanden 20 vil således vide, at de kunne forbindes på diverse forskellige måder, f.eks. kunne lågdelen 2 og husdelen 1 have gensidigt indgribende gevind, og lågdelen skrues på husdelen 1.The layer part 2 is preferably pressed onto the housing part 1 and held there by friction alone, but this is not important for the invention. Those of skill in the art will thus know that they can be connected in various different ways, e.g. For example, the lid part 2 and the housing part 1 could have mutually engaging threads and the lid part was screwed onto the housing part 1.

Lågdelen 2 kunne også indbefatte en beskyttende rist eller lignende i åbningen 5 for at forhindre mekanisk skade på den akustiske 25 transducer.The lid portion 2 could also include a protective grate or the like in the aperture 5 to prevent mechanical damage to the acoustic transducer.

Fig. 5 og 6 illustrerer en alternativ udførelsesform af opfindelsen, i hvilken den akustiske tryktransducer 6 udgør en del af inertimassen. I det væsentlige adskiller huset i fig. 5 sig kun fra det i fig. 3 ved, at understøtningsorganet 13 er udeladt.FIG. 5 and 6 illustrate an alternative embodiment of the invention in which the acoustic pressure transducer 6 forms part of the inertial mass. Essentially, the housing of FIG. 5 only from the one shown in FIG. 3 in that the support member 13 is omitted.

30 I stedet for at hvile på understøtningsorganet 13, hviler den akustiske tryktransducer på skulderen 12. Massen af den akustiske tryktransducer 6 udgør således en del af den samlede seismiske masse, når den finder plads i det ringformede legeme 11. På denne måde er den centrale akse af den akustiske tryktransducer automatisk rettet ind DK 176324 B1 7 med den for det ringformede legeme 11, dvs. at massemidtpunktet af massefordelingen af inertimassen falder præcist sammen med aksen af den akustiske tryktransducer 6.Instead of resting on the support member 13, the acoustic pressure transducer rests on the shoulder 12. The mass of the acoustic pressure transducer 6 thus forms part of the total seismic mass as it takes up space in the annular body 11. In this way, the central axis of the acoustic pressure transducer automatically aligns with that of the annular body 11, i. the mass center of the mass distribution of the inert mass coincides exactly with the axis of the acoustic pressure transducer 6.

Om end den akustiske tryktransducer 6 i de illustrerede udfø-5 relsesformer kun befinder sig delvist inden i det ringformede legeme 11, dvs. fremstår let over det i den retning, som vender mod åbningen 5, er det også muligt at placere hele den akustiske tryktransducer 6 inden i det ringformede legeme, således at centrum for den akustiske måling rent faktisk falder sammen med massemidtpunktet af massefordelingen.Although the acoustic pressure transducer 6 in the illustrated embodiments is only partially within the annular body 11, i. It is also possible to position the entire acoustic pressure transducer 6 within the annular body so that the center of the acoustic measurement coincides with the center of mass of the mass distribution.

10 Selv om de illustrerede udførelsesformer anvender en enkelt vi brationssensor med en enkelt inertimasse, er det også muligt at placere et antal diskrete vibrationssensorer omkring tryktransduceren, så længe deres massemidtpunkt af massefordelingen falder sammen med den centrale akse af den akustiske tryktransducer 6.Although the illustrated embodiments employ a single vibration sensor with a single inertial mass, it is also possible to place a number of discrete vibration sensors around the pressure transducer as long as their center of mass of the mass distribution coincides with the central axis of the acoustic pressure transducer 6.

15 Fagmanden vil endvidere indse, at både accelerationssensoren og den akustiske tryktransducer kan afvige fra den foretrukne udførelsesform i konstruktion. Navnlig behøver den akustiske tryktransducer ikke at være en kapacitiv mikrofon, men kunne være en hvilken som helst anden passende type, eksempelvis piezoelektrisk eller dynamisk.The person skilled in the art will further appreciate that both the acceleration sensor and the acoustic pressure transducer may differ from the preferred embodiment in construction. In particular, the acoustic pressure transducer need not be a capacitive microphone, but could be any other suitable type, for example, piezoelectric or dynamic.

20 Ifølge det andet aspekt af opfindelsen anvendes en dobbelt sen sor som beskrevet ovenfor til lyd- og vibrationsmålinger, dér hvor korrelationen mellem lydtryk og vibration er vigtig for evalueringen af målingen, f.eks. til bestemmelse af, hvordan dele af et automobil påvirker lyden i passagerkabinen.According to the second aspect of the invention, a dual sensor as described above is used for sound and vibration measurements, where the correlation between sound pressure and vibration is important for the evaluation of the measurement, e.g. to determine how parts of an automobile affect the sound in the passenger compartment.

25 Til dette formål placeres en dobbelt sensor, eller oftere et antal dobbelte sensorer ifølge opfindelsen på forskellige steder på dele i passagerkabinen af et automobil. De dobbelt sensorer forbindes til passende måleapparatur, der tillader måling og evaluering af korrelation mellem den målte lyd og den målte vibration.For this purpose, a dual sensor, or more often a plurality of dual sensors according to the invention, are placed at various locations on parts in the passenger compartment of an automobile. The dual sensors are connected to appropriate measuring devices that allow the measurement and evaluation of correlation between the measured sound and the measured vibration.

30 Om end den foretrukne anvendelse er i automobilindustrien, vil fagmanden indse, at fremgangsmåden og den dobbelte sensor ifølge den foreliggende opfindelse også kan anvendes i utallige andre anvendelser, hvor det er af betydning at korrelere lyd- og vibrationsmålinger.Although the preferred application is in the automotive industry, those skilled in the art will appreciate that the method and dual sensor of the present invention can also be used in countless other applications where it is important to correlate sound and vibration measurements.

Claims

A double sensor for measuring sound and vibration, comprising a housing in which there is at least one inertia mass of an accelerometer and an acoustic pressure transducer (6), wherein the at least one inertia mass is distributed around a central axis of the sensor, thereby providing a mass distribution whose mass center point coincides with the central axis and where the acoustic pressure transducer (6) is located centrally, coinciding with the central axis, characterized in that the acoustic pressure transducer (6) is 10 located on the central axis at a location which is at least partially coincident with the vertical projection of the at least one inertial mass on the central axis.

Double sensor according to claim 1, characterized in that the at least one inertial mass comprises a generally annular body 15 (11) with a central opening and that the acoustic pressure transducer (6) is located in this central opening.

Double sensor according to claim 2, characterized in that the acoustic pressure transducer (6) takes place in the central opening and is in fixed communication with the annular body (11), so that it forms part of the at least one inertial mass.

Double sensor according to claim 2, characterized in that the housing has a generally cylindrical inner cavity having a bottom (8) and a side wall, and that the inertial mass is in such a manner in the cavity that at least one piezoelectric element (10) ) takes place between the periphery of the annular body (11) and the side wall of the cavity.

A dual sensor according to any one of the preceding claims, wherein the housing comprises at least one plane exterior surface (3).

Method for measuring sound and vibration, characterized in that a dual sensor according to any one of claims 1 to 5 is placed on a surface on which it is to be measured that the dual sensor is connected to an appropriate measuring device, and that a measurement is performed.

Use of a method according to claim 6 and a dual sensor according to any one of claims 1 to 5 for performing measurements DK 176324 B1 on a transport means.

Use of a method according to claim 7, wherein the means of transport is an automobile. 5