Acoustic panel, electric appliance and method of assembling an electric appliance

Abstract

An acoustic panel (1) for an electric appliance (2) with a tank (21) is specified, wherein - the acoustic panel (1) comprises an inner plate ( 11) facing the tank (21) and an outer plate (22) facing away from the tank (21), - a resonator volume (18) is arranged between the inner plate (11) and the outer plate (12), - the acoustic panel (1) comprises an opening (185) coupled to the resonator volume (18), and - the acoustic panel (1) is configured to be mounted to at least one reinforcement bar (22) on an outer wall ( 210) of the tank (21) wherein the inner plate (21) of the acoustic panel (1) is located closer to the outer wall (210) of the tank (21) than a surface (220) of the reinforcement bar (22) that faces away from the tank (21). Further, an electric appliance (2) and a method of assembling an electric appliance (2) are specified.

Description

[0001]P2024,0671 WO N / P240069WO01 September22,2025 -1 - DescriptionAcoustic panel, electric appliance, and method of a ssemblingan electricapplianceThe present disclosure relates to an acoustic panel , anelectric appliance, and to a method of assembling a n electricappliance.Electric appliances such as those used in energy di stributionnetworksmayproduce noise during operation.Embodiments of the disclosure relate to a way to da mpen noiseduring operation ofan electricappliance.According to an embodiment of an acoustic panel, th e acousticpanelisconfigured foran electricappliance with a tank,wherein the acoustic panel comprises an inner plate facingthe tank and an outer plate facing away from the ta nk. Aresonator volume is arranged between the inner plat e and theouter plate. The acoustic panel comprises an openin g coupledto the resonator volume. In particular, the acousti c panel isconfigured to be mounted to at least one reinforcem ent bar onan outer wall of the tank wherein the inner plate o f theacousticpanelislocated closerto the outerwall ofthetank than a surface of the reinforcement bar that f aces awayfrom the tank. In particular, the acoustic panel co mprises arib structure thatextendsfrom the outerplate to the innerplate, wherein the rib structure subdivides a volum e of theacoustic panel into a plurality of chambers, wherei n at leastone ofthe chambersrepresentsa resonatorvolume. P2024,0671 WO N / P240069WO01 September22,2025 -2 -The acoustic panel may be configured to absorb acou sticenergy and to generate an acoustic pressure that is incounter-phase to an excitation pressure coming from the outerwall of the tank during operation of the electric a ppliance.Due to the resonant character, the acoustic panel c an bespecifically tuned to dampen one or more of the mos t criticalfrequency bands in the noise caused by the electricappliance. The acousticpanelmaybe configured such thatthereinforcement bars of the tank may be used to mount theacoustic panel. In contrast to conventional solutio ns, anadditional supporting construction spaced apart fro m the tankcan be dispensed with.Further, the addition of the acoustic panel does no t or atleast not significantly increase the overall dimens ions ofthe electricappliance.Further, access to the electric appliance, for inst ance formaintenance purposes is facilitated compared to sol utionswhere a supporting structure is mounted to the tank or / andto the ground and extends around the tank at a dist ance fromthe tank.For example, the electric appliance comprises a liq uid-immersed, in particular an oil-immersed power devic e. Thus,the tankreceivesthe powerdevice and the liquid.For example, the power device comprises at least on e of: atransformer, a phase shifter, a reactor, an inducto r. P2024,0671 WO N / P240069WO01 September22,2025 -3 -For example, the electric appliance is configured t o be usedin an energydistribution network.For example, the inner plate and the outer plate of theacousticpanelextend in parallelorsubstantially in parallelto one another.Forexample,the acoustic panelcomprises side walls extending obliquely or perpend icularlywith respect to the inner plate and / or to the outer plate.The inner plate, the outer plate and the side walls takentogethermaydefine a volume thatcomprisesone or moreresonator volumes.For example, the inner plate and / or the outer plate comprisesor consists of a metal such as carbon steel, stainl ess steel,or aluminum. Alternatively or in addition, at least one ofthe innerplate orthe outerplate maycomprise or consistof a plasticsmaterial.The reinforcement bars are not limited with respect to theircross-section.Forexample,the reinforcementbars mayhave aU-shaped, C-shaped, L-shaped, I-shaped, T-shaped or arectangularcross-section.Further, the electric appliance may comprise reinfo rcementbars that differ from one another with respect to a shapeand / or the dimensions of the cross-section. For exa mple, atleast some of the reinforcement bars are arranged v erticallyor at least substantially vertically in space. Alte rnativelyor in addition, horizontal reinforcement bars may b eprovided. Alternatively or in addition, oblique rei nforcementbars may be provided, for instance diagonal reinfor cementbars. P2024,0671 WO N / P240069WO01 September22,2025 -4 -For example, the acoustic panel is configured to be mountedbetween reinforcementbarsofthe tankarranged on the outerwall of the tank, in particular between two directl y adjacentreinforcementbars.Thus,a gap between adjacentreinforcement bars may be at least partly filled wi th theacousticpanel.Alternatively, the acoustic panel may be mounted on ly on oneside ofthe acousticpanelto a reinforcementbar. Forexample, this may apply at an edge or a corner of t he tank.In this case, an additional construction may be use d to mountthe acousticpanelon the otherside.According to a further embodiment of the acoustic p anel, theacoustic panel is configured to dampen at least one specificacousticfrequencyband ofthe electricappliance. Thus,theacoustic panel may be specifically designed to effi cientlydampen noise in a frequency band where the noise em ission ofthe electric appliance during operation is particul arly high.For example, typical dominant noise frequencies are around100 Hz,120 Hz,300 Hz,or400 Hz.For example, parameters of the resonator volume and / or of theopening may be used to appropriately tune the dampe ningproperties. Further, parameters affecting the stiff ness ofthe acoustic panel and / or parameters of a filling m ateriallocated in the resonator volume may be used to appr opriatelytune the dampening properties of the acoustic panel . Thefrequencytuning maybe done during the production processor byan appropriate modification ofalreadyproduced acoustic panels. P2024,0671 WO N / P240069WO01 September22,2025 -5 -According to a further embodiment of the acoustic p anel, theacoustic panel is configured to provide two specifi c acousticdampening frequency bands. For example, a center-to -centerdistance between two adjacent acoustic dampening fr equenciesisatleast10 Hzoratleast20 Hzand / oratmost 300 Hzor atmost200 Hz.According to a further embodiment of the acoustic p anel,the acousticpanelcomprisesa tube-like structure thatformsthe opening. For example, the tube-like structure m ay have around cross-section. For example, a diameter of the cross-section is in a range from 5 mm to 300 mm. A height of thetube-like structure isin a range from 5 mm to 300 mm,forexample. Here, the term “height” refers to the exte nt in adirection perpendicularto the cross-section. Forexample,the acousticpanelcomprisesatleast one tube-like structure and / or at most 200 tube-like structu res or atmost 100 tube-like structures or at most 50 tube-li kestructures.Parameters of the tube-like structure such as the c ross-section orthe heightmaybe used to appropriately tune the frequencyresponse ofthe acousticpanel.According to a further embodiment of the acoustic p anel, theopening provides a gas exchange between the resonat or volumeand an environment of the acoustic panel. For examp le, theopening is located in the inner plate of the acoust ic panelthat faces the outer wall when mounted to the tank. Thus, theacoustic pressure in counter-phase with the excitat ionpressure may be directed from the acoustic panel to wards theouter wall of the tank. However, the opening may al so be P2024,0671 WO N / P240069WO01 September22,2025 -6 -located in the outer plate or in a side wall of the acousticpanel.According to a further embodiment of the acoustic p anel, theopening provides a gas exchange between the resonat or volumeand a furthervolume within the acousticpanel.In thiscase,the gas exchange from and into the resonator volume may occurwithin the volume of the acoustic panel. For exampl e, theacoustic panel comprises at least two resonator vol umes thatare connected to one anothervia the opening.According to a further embodiment of the acoustic p anel, theacoustic panel comprises a plurality of resonator v olumes,wherein at least some of the resonator volumes comp rise anassociated opening. For example, each of the resona torvolumes is connected to at least one further resona tor volumeofthe acousticpaneland / orto the environment.According to a further embodiment of the acoustic p anel, theacoustic panel comprises a rib structure that exten ds atleastin regionsfrom the outerplate to the inner plate.Forexample, the inner plate and the outer plate are me chanicallyconnected to one another via the rib structure. Thi s maysignificantly increase the stiffness of the acousti c panel.It has been found that the stiffness of the acousti c panelsignificantly affects the acoustic dampening proper ties.In particular, the rib structure may be used to inc rease thestiffness of the acoustic panel without having to i ncreasethe thickness of the inner plate and / or the outer p late. Thishelps to keep the weight of the acoustic panel low. P2024,0671 WO N / P240069WO01 September22,2025 -7 -The rib structure may subdivide the volume into a p luralityof chambers, wherein at least one of the chambers r epresentsa resonator volume. Thus, the volume of the resonat or volumecan be defined by an appropriate configuration of t he ribstructure. The rib structure may comprise one rib o r apluralityofribsthatextendshorizontallyand / or one rib ora plurality of ribs that extends vertically in spac e when theacousticpanelismounted to the tank.The rib structure may be formed from the same mater ial as theinner plate and / or the outer plate. The rib structu re maycomprise a metal, for instance. Alternatively, a ma terial ofthe rib structure maybe differentfrom a material oftheinner plate or the outer plate. The rib structure m aycomprise a plasticsmaterial,forinstance.According to a further embodiment of the acoustic p anel, atleast some of the openings associated to the resona torvolumes provide a gas exchange between the resonato r volumeand an environment of the acoustic panel. For examp le, eachof the resonator volumes communicates with the envi ronmentvia an associated opening.According to a further embodiment of the acoustic p anel, atleast some of the openings associated to the resona torvolumes provide a gas exchange between adjacent res onatorvolumes of the acoustic panel. For example, each of theresonator volumes communicates with at least one fu rtherresonatorvolume via an associated opening.The acoustic panel may also be air-tight, so that t here is noor at least no significant gas exchange with the en vironment. P2024,0671 WO N / P240069WO01 September22,2025 -8 -The acoustic panel may also comprise at least one o peningtowards the environment and at least one opening be tween tworesonatorvolumes.According to a further embodiment of the acoustic p anel, theresonator volume is free from a filling material. I nparticular, some or all of the resonator volumes ma y be freefrom the filling material.According to a further embodiment of the acoustic p anel, theresonator volume includes a filling material. For e xample,the filling is provided as a mat or as a granular m aterial.Additional energy dissipation may be achieved by me ans of thefilling material.According to a further embodiment of the acoustic p anel, thefilling material has a density of at most 500 kg / m³ . Forexample,the densityisin a range from 5 kg / m³to 500 kg / m³.For example, mineral wool typically has a density i n a rangefrom 30 to 200 kg / m³.Alternativelyorin addition thefilling material may comprise an acoustic foam. A f illingmaterial having a low density helps to keep the wei ght of theacousticpanellow.According to a further embodiment of the acoustic p anel, thefilling materialhasa densityin a range from 0.5 g / cm³to5 g / cm³. Thus, the filling material has a comparabl y highdensity. For example, the filling material may comp rise aplastics material such as polyvinyl chloride (PVC).Alternativelyorin addition,the filling material maycomprise a granular rubber material such as granula r EPDM(ethylene propylene diene monomer). It has turned o ut that a P2024,0671 WO N / P240069WO01 September22,2025 -9 - filling materialhaving a comparablyhigh density, inparticular granular rubber, is suitable to efficien tly dampennoise with frequencies occurring during operation o f electricapplianceswith a powerdevice immersed in a tank.According to a further embodiment of the acoustic p anel, agrain size of the filling material is in a range fr om 0.1 mmto 5 mm. Granular material with a grain size in thi s rangehas been proven to be particularly efficient for da mpeningnoise in typical emission frequency bands of electr icappliances.However,non-granularfilling material mayalso be used.According to a further embodiment of the acoustic p anel, atleast one of the inner plate or the outer plate has athickness in a range from 2 mm to 6 mm. It has turn ed outthat an efficient noise reduction can be obtained w hile theweight of the acoustic panel can be kept low at the sametime.According to a further embodiment of the acoustic p anel, athicknessofthe acousticpanelisin a range from 10 mm to300 mm. The thickness refers to the extent of the a cousticpanel in a direction perpendicular to the outer pla te of theacoustic panel. In particular, the thickness of the acousticpanelmaybe used to adaptthe efficiencyofnoise dampeningand / or the spectral response of the acoustic panel. Forexample, the thickness of the acoustic panel may be used todefine the volume ofthe resonatorvolume.According to a further embodiment of the acoustic p anel, theacoustic panel comprises a mounting region for moun ting theacousticpanel.In particular,the mounting region laterally P2024,0671 WO N / P240069WO01 September22,2025 -10 -projects beyond the inner plate. For example, the a cousticpanel comprises two mounting regions extending alon g twoopposite edgesofthe acousticpanel.Forexample, themounting region is configured to receive a mechanic alconnectorsuch asa screw,a bolt,ora clamp.For example, the mounting region is formed by a par t of theouter plate that laterally projects beyond the inne r plate.Alternatively or in addition, the mounting region m ay beformed by an extension attached to the outer plate.Further, an electric appliance is specified. In par ticular,the electric appliance comprises at least one acous tic panelasdescribed above and a tank.According to an embodiment of the electric applianc e, thetank comprises a plurality of reinforcement bars ar ranged onan outer wall of the tank wherein the acoustic pane l ismounted to at least one of the reinforcement bars w herein theinner plate of the acoustic panel is located closer to theouter wall of the tank than a surface of the reinfo rcementbarthatfacesawayfrom the tank.For example, the acoustic panel may be mounted betw een tworeinforcement bars of the plurality of reinforcemen t bars, inparticular between two directly adjacent reinforcem ent bars.According to a further embodiment of the electric a ppliance,the acoustic panel is configured to generate an aco usticpressure thatisin counter-phase to an excitation pressurecoming from the outer wall of the tank during opera tion ofthe electric appliance. Thus, the acoustic panel ma y bedesigned as a resonant element to specifically damp en noise P2024,0671 WO N / P240069WO01 September22,2025 -11 -in one or more acoustic frequency band(s) that domi nates inthe noise spectrum ofthe electricappliance. Forexample,the acousticpanelextendsinto a gap betweentwo directly adjacent reinforcement bars in a top v iew ontothe electric appliance. Alternatively or in additio n, anacoustic panel of the electric appliance may be mou nted toonly one of the reinforcement bars as described abo ve.According to a further embodiment of the electric a ppliance,the inner plate is arranged completely within a gap betweentwo adjacentreinforcementbarsin a top view onto theelectric appliance. Thus, the space between the rei nforcementbars can be used, at least in part, for the acousti c panel.For example, all gaps between two adjacent reinforc ement barsare at least partly filled with one acoustic panel.According to at least one embodiment of the electri cappliance,the acousticpanelcomprisesa mounting regionthat overlaps with one of the reinforcement bars. I nparticular, a sealing and / or damping material may b e arrangedbetween the mounting region and the reinforcement b ar. Thesealing and / or damping material may be used to redu ce atransfer of vibrations of the outer wall of the tan k to theacoustic panel via the mounting region, and / or to s eal aclosed area created between the acoustic panels, th ereinforcement bars, and the outer wall of the tank.For example, the sealing and / or damping material co mprises arubber material or cork rubber. In this area also o therdamping systemscan be used,forexample single or stacked spring washers. P2024,0671 WO N / P240069WO01 September22,2025 -12 -According to at least one embodiment of the electri cappliance, a distance between a support structure o f theacoustic panel and the tank is sealed using a seali ng system.For example, the sealing system comprises cork, rub ber oranothersealing material.Forexample,a thickness ofthe sealing system isin a range from 1 mm to 500 mm.According to at least one embodiment of the electri cappliance, a distance between the inner plate of th e acousticpaneland the outerwallofthe tankisin a range from 0 mmto 500 mm. Thus, the inner plate may directly adjoi n theouter wall of the tank. Alternatively, the inner pl ate may bespaced apart from the outer wall of the tank. For e xample,the distance between the inner plate of the acousti c paneland the outerwallofthe tankisatleast1 mm or atleast 5 mm oratleast10 mm.Further, a method of assembling an electric applian ce isspecified.According to an embodiment of the method, the metho dcomprisesthe stepsofproviding an electricpower device, the step offorming a tankthatextendsaround the electricpower device wherein the tank comprises a plurality ofreinforcement bars arranged on an outer wall of the tank andthe step ofmounting an acousticpanelto atleast one oftheplurality of reinforcement bars wherein the inner p late ofthe acoustic panel is located closer to the outer w all of thetank than a surface of the reinforcement bar that f aces awayfrom the tank. The method steps can be performed in theindicated order.However,thisisnotnecessary. P2024,0671 WO N / P240069WO01 September22,2025 -13 -According to an embodiment of the method, the acous tic panelcomprisesa resonatorvolume,wherein atleastone specificacoustic dampening frequency band of the acoustic p anel istuned by modifying at least one resonator parameter . Inparticular, this may be done in already produced or even inalready mounted acoustic panels. For example, the f requencytuning maybe obtained byadding an opening and / or bychanging a size of an existing opening and / or by ad ding ormodifying a tube-like structure.According to a further embodiment of the method, th e step ofmounting the acoustic panel is performed prior to t he step offorming the tank. Thus, the acoustic panel can be p rovided ina pre-assembled mannertogetherwith a partofthe tank.Inconventional approaches, in contrast, the tank is f ormedfirst and the sound panels are attached to a suppor tingstructure thatextendsaround the finished tankat a minimumdistance from the tank which is typically about 500 mm.The method is particularly suitable for the electri cappliance described above.Featuresand advantages describedin connection with the acoustic panel or the electr icappliance can therefore be used forthe method and vice versa. Featuresdescribed in connection with atleastone embodimentmay be combined with other features described in co nnectionwith other embodiments unless they are contradictor y.The accompanying figuresare included to provide a furtherunderstanding. In the figures, elements of the same structureand / orfunctionalitymaybe referenced bythe same reference signs.Itisto be understood thatthe embodiments shown in P2024,0671 WO N / P240069WO01 September22,2025 -14 -the figures are illustrative representations and ar e notnecessarilydrawn to scale. In the Figures:Figure 1A shows a schematic sectional view of an el ectricappliance with acoustic panels according to an embo diment,Figure 1B shows a schematic side view of an electri cappliance with acoustic panels according to an embo diment,Figure 2A shows a schematic sectional view of an el ectricappliance with acoustic panels according to an embo diment,Figure 2B shows a schematic side view of an electri cappliance with acoustic panels according to an embo diment,Figure 3A shows a perspective view of a detail of a n electricappliance with an acoustic panel according to an em bodiment,Figure 3B showsa sectionalview ofa detailofan electricappliance with an acoustic panel according to an em bodiment,Figure 4A shows a perspective view of a detail of a n electricappliance with an acoustic panel according to an em bodiment,Figure 4B shows a perspective view of a detail of a n electricappliance with an acoustic panel according to an em bodiment,Figure 5A shows a schematic side view of an electri cappliance with acoustic panels according to an embo diment,Figure 5B shows a further schematic side view of an electricappliance with acoustic panels according to an embo diment,Figure 6 shows a schematic representation of a meth odaccording to an embodiment, P2024,0671 WO N / P240069WO01 September22,2025 -15 - Figure 7 showssimulation resultsofa response of anembodiment of an acoustic panel as a function of th efrequency.While the disclosure is amendable to various modifi cationsand alternative forms,specificsthereofhave been shown byway of example in the figures and will be described indetail.Itshould be understood,however,thatthe intentionis not to limit the disclosure to the particular em bodimentsdescribed. On the contrary, the intention is to cov er allmodifications, equivalents, and alternatives fallin g withinthe scope of the disclosure defined by the appended claims.In the embodiment shown in Figures 1A and 1B, three differentexamples of an acoustic panel 1 are illustrated, wh erein eachacoustic panel 1 configured for an electric applian ce 2 witha tank21.The acousticpanel1 comprisesan inner plate 11facing the tank 21 and an outer plate 12 facing awa y from thetank21.In the acoustic panel 1 on the left, a volume 13 be tween theinnerplate 11 and the outerplate 12 representsa resonatorvolume 18. The acoustic panel 1 comprises an openin g 185coupled to the resonator volume 18. The acoustic pa nel 1 isconfigured to be mounted to at least one reinforcem ent bar 22on an outer wall 210 of the tank 21. The inner plat e 11 ofthe acoustic panel 1 is located closer to the outer wall 210ofthe tank21 than a surface ofthe reinforcement bar22 thatfacesawayfrom the tank21.The examples of acoustic panels 1 in the middle and on theright differ from the example on the left in that t he volume13 is subdivided in a plurality of resonator volume s 18. Thevolume 13 of the acoustic panel is subdivided in th e vertical P2024,0671 WO N / P240069WO01 September22,2025 -16 -direction, whereas the volume of the acoustic panel on theright is subdivided both vertically and horizontall y in spacewhen mounted to the tank21. Each resonatorvolume 18 comprisesan opening 185. In theembodiment of Figures 1A and 1B, the openings 185 p rovide anair exchange between the resonator volumes 18 and t heenvironment. The openings 185 are arranged on the i nner plate11 ofthe acousticpanel1.The acoustic panels 1 are configured to absorb acou sticenergy and to generate an acoustic pressure that is incounter-phase to an excitation pressure coming from the outerwall 210 of the tank 21 during operation of the ele ctricappliance 2.The resonator volumes 18 are separated from one ano ther via arib structure 17 thatextendsfrom the innerplate 11 to the outerplate 12. The opening 185 isformed bya tube-like structure 187.Forexample, the tube-like structure may have a round c ross-section. For example, a diameter of the cross-secti on is in arange from 5 mm to 300 mm. A height of the tube-lik estructure is in a range from 5 mm to 300 mm, for ex ample.Parameters of the tube-like structure 187 such as t he cross-section or the height and / or the volume of the reso natorvolumes 18 may be used to appropriately tune the fr equencyresponse of the acoustic panel in such a way that t heacoustic panel 1 efficiently dampens noise in a fre quencyband where the noise emission of the electric appli ance 2during operation isparticularlyhigh. P2024,0671 WO N / P240069WO01 September22,2025 -17 -The number of tube-like structures may be varied in wideranges. For example, the acoustic panel 1 comprises at leastone tube-like structure 187 and / or at most 200 tube -likestructures187 oratmost100 tube-like structures 187 orat most50 tube-like structures187.The rib structure 17 that separates the resonator v olumes 18from one another extends from the outer plate 12 to the innerplate 11. Thus, the volume of the individual resona torvolumes 18 may be adapted by the configuration of t he ribstructure 17. The rib structure 17 may be formed fr om thesame material as the inner plate 11 and / or the oute r plate 12orfrom a differentmaterial.Further, the mechanical connection between in the i nner plate11 and the outerplate 12 via the rib structure 17 increasesthe stiffness of the acoustic panel 1. This may res ult inminimized low frequency vibrations of the outer pla te 12.In the embodiment shown in Figures 1A and 1B, the a cousticpanels1 are each mounted in a gap 221 between two adjacentreinforcement bars 22. Thus, the gap 221 is at leas t partlyfilled with the acoustic panel 1 so that this space can beused fornoise dampening.Different ways for mounting the acoustic panel 1 to thereinforcement bars 22 will be described in connecti on withFigures3A,3B,4A,and 4B. Unlike the schematicrepresentationsofFigures1A and 1B,the acoustic panel 1 can also be mounted to only on ereinforcementbar22.Forexample,thismaybe the case atan P2024,0671 WO N / P240069WO01 September22,2025 -18 - edge ora cornerofthe tank21.Here,the side of theacoustic panel opposite to the reinforcement bar 22 may beconnected to the tank 21 or to another acoustic pan el 1 bymeans ofa dedicated supportstructure.During operation of the electric appliance 2, the a cousticpanels 1 dampen the noise of an electric power devi ce 20 ofthe electric appliance 2. For example, the electron ic powerdevice 20 may comprise or consist of a transformer, a phaseshifter,a reactor,oran inductor. In particular,almostthe complete outerwalls210 ofthe tank21 maybe covered byacousticpanels1.By tuning the resonant properties, the acoustic pan el 1 canbe specifically designed such that the noise reduct ion istuned to one or more of the particular frequency ba nds of thenoise emitted by the electric appliance 2 during op eration.The acoustic frequency bands are specific to the el ectricappliance 2. In particular, these frequencies may a lso dependon the net frequency of the energy distribution net work.For example, typical dominant noise frequencies are around100 Hz,120 Hz,300 Hz,or400 Hz. Optionally,the resonatorvolumes18 maybe filled with afilling material 14. The filling material 14 may he lp toobtain a further noise reduction. The filling mater ial 14 mayhave a comparably low density. For example, the den sity ofthe filling materialisin a range from 5 kg / m³to 500 kg / m³.For example, a mineral wool or an acoustic foam may be used. P2024,0671 WO N / P240069WO01 September22,2025 -19 - Alternatively,a comparablydense filling material 14 maybe used such asa plasticsmateriallike PVC. Alternatively,the filling materialmaycomprise a granularrubber material such as granular EPDM (ethylene pro pylenediene monomer).This material can be provided as recycling material , forexample.For example, a grain size of the filling material 1 4 is in arange from 0.1 mm to 5 mm.The inner plate 11 and / or the outer plate 12 may ha ve athickness in a range from 2 mm to 6 mm. As the thic kness ofthe inner plate 11 and the outer plate 12 affects t hestiffness of the acoustic panel 1, the thickness of the innerplate 11 and / or the outer plate 12 may also be used to tunethe acousticfrequencyresponse.A thickness of the acoustic panel 1 may be in a ran ge from10 mm to 300 mm,forexample.In the embodiment of Figures 1A and 1B, the inner p late 11 ofthe acoustic panel 1 is spaced apart from the outer wall 210of the tank 21. However, the inner plate 11 may als o directlyadjoin the tank 21. For example, the distance betwe en theinner plate 11 of the acoustic panel 1 and the oute r plate210 of the tank 21 is in a range from 0 mm to 500 m m.A distance between a support structure of the acous tic panel1 and the tank 21 may be sealed using a sealing sys tem. Forexample,the sealing system comprisescork,rubber oranother P2024,0671 WO N / P240069WO01 September22,2025 -20 -sealing material. For example, a thickness of the s ealingsystem is in a range from 1 mm to 500 mm.For example, the inner plate 11 and / or the outer pl ate 12comprises a metal such as carbon steel, stainless s teel oraluminium,ora plasticsmaterial.The resonant response characteristics of the descri bedacoustic panels 1 are illustrated in Figure 7. Figu re 7depictssimulation resultsofa frequencyresponse curve of an acousticpanel,where an airpressure p between theacoustic panel and the outer wall of the tank is il lustratedfora vibration ofthe outerwallofthe tankwith an amplitude of1 mm.Due to the resonantbehaviorof the acousticpanel,the curve haspronounced minima at frequenciesof100 Hz,143 Hz,and 320 Hz.Thus, two or more frequency bands may be efficientl y dampenedby appropriately configuring the resonator volume(s ) of theacousticpanel1.Asdescribed above,the position oftheseminima can be tuned by appropriately changing the p arametersofthe acousticpanel1.The embodiment illustrated in Figures 2A and 2B sub stantiallycorresponds to the embodiment depicted in Figures 1 A and 1B.In departure therefrom, the resonator volumes 18 of theacousticpanels1 are connected to one anothervia openings185 formed by tube-like structures 187. In the acou stic panel1 depicted on the left, resonator volumes 18 arrang ed side byside in the horizontal direction are connected to o neanother. Exemplarily, the acoustic panel 1 comprise s twelveresonatorvolumes18. P2024,0671 WO N / P240069WO01 September22,2025 -21 -In the acoustic panel 1 depicted on the right and i n themiddle, resonator volumes 18 arranged one above the other inthe vertical direction are connected to one another .Exemplarily,these acousticpanels1 comprisessix resonator volumes18.In these embodiments according to Figures 2A and 2B , the gasexchange occurs within the acoustic panels 1. Thus, theacoustic panels may be air-tight or substantially a ir-tight.However, one or more of the resonator volumes 18 ma y beconnected to the environment as described in connec tion withFigures1A and 1B.Figures 3A and 3B illustrate an embodiment of an ac ousticpanel1 mounted to a T-shaped reinforcementbar22 on anouter wall 210 of a tank 21 of an electric applianc e 2. Theacoustic panel 1 comprises an inner plate 11 and an outerplate 12 extending in parallel to one another. A si dewall 19is arranged between the inner plate 11 and the oute r plate12. As described in connection with Figures 1A, 1B, 2A, and2B,the volume 13 comprisesatleastone resonator volume 18with an opening 185. This is not explicitly shown i n Figures3A and 3B forthe sake ofsimplicity.The acoustic panel 1 comprises a mounting region 15 . Themounting region 15 laterally extends beyond the inn er plate11 and is configured to overlap with the reinforcem ent bar 22when mounted to the outerwall210 ofthe tank21. Themounting region 15 may be formed by a part of the o uter plate12.Alternatively,the mounting region 15 mayalso be formedby a separate element attached to the outer plate 1 2 asillustrated in Figure 4A,forinstance. P2024,0671 WO N / P240069WO01 September22,2025 -22 -The mounting region 15 and means for mechanically m ountingthe acoustic panel 1 to the reinforcement bars 22 m ay beadapted to the cross-section of the reinforcement b ars 22. InFigure 3A, the reinforcement bars 22 have a T-shape d cross-section. However, other geometries may also be used for thereinforcement bars, for example a U-shaped or subst antiallyrectangular cross-section of the reinforcement bars 22. Othercross-sections such as C-shaped, L-shaped, or I-sha ped mayalso be used.The mounting region 15 overlaps with the reinforcem ent bar22.The mechanicalconnection between the acoustic panel1and the reinforcement bar 22 is obtained via a clam p 31 thatdirectly adjoins the reinforcement bar 22 and is se cured tothe acousticpanel1 via a washer33 and a nut32.A sealing and / or damping material 222 is arranged b etween themounting region 15 of the acoustic panel and the su rface 220of the reinforcement bar 22, for example the dampin g material222 comprisesa rubber.In the embodiments of Figures 4A and 4B, the reinfo rcementbars 22 have a U-shaped cross-section. In the embod iment ofFigure 4A, the mounting region 15 is formed by an e xtension151 attached to the outerplate 12 ofthe acoustic panel.Theextension 151 has a hole or a cutout to receive a s crew 34extending into a blind bushing 225 of the reinforce ment bar22.The embodiment of Figure 4B substantially correspon ds to theembodiment of Figure 4A. However, the mounting regi on 15 is P2024,0671 WO N / P240069WO01 September22,2025 -23 -formed by a portion of the outer plate 12 that over laps withthe reinforcementbar22.Figures 5A and 5B illustrate two side views of an e lectricappliance 2 with a tank 21 and a plurality of acous tic panels1 that may be configured as described in the previo usfigures. Figure 5B further schematically illustrate s theelectric power device 20 immersed in a liquid withi n tank 21.Figures 5A and 5B illustrate that almost the entire surfaceof the outer wall 210 of the tank 21 may be covered withacoustic panels 1 so that an efficient noise reduct ion can beobtained. Compared to conventional solutions, the a cousticpanels1 do notsignificantlyincrease the size of theelectric appliance 2. Further, access to the tank 2 1 isfacilitated.Figure 6 illustrates an embodiment of a method of a ssemblingan electric appliance. For better understanding, st ructuralfeaturesdescribed in connection with the previous figuresare used even though these elements are not explici tly shownin Figure 6.In a step S1, an electric power device 20 is provid ed. In astep S2, a tank is formed that extends around the e lectricpowerdevice.The tank21 comprisesa pluralityofreinforcement bars 22 arranged on an outer wall 210 of thetank 21. In a step S3, an acoustic panel 1 is mount ed to atleastone ofthe reinforcementbars22 wherein the inner plate ofthe acousticpanel1 islocated closerto the outerwall of the tank 21 than a surface 220 of the reinf orcementbar22 thatfacesawayfrom the tank. P2024,0671 WO N / P240069WO01 September22,2025 -24 -The method can be performed in the indicated order.However,thisisnotnecessarilyrequired.Rather, atleast partofstep S3 maybe performed priorto step S2. Forexample, at least one acoustic panel 1 may be preas sembled toa partofthe tank.Thus,partsofthe tankmaybe provided with an acousticpanelbefore the tank21 hasbeen completed. Thismayhelp to facilitate the assembling process ofthe electricappliance 2.In particular, the method can be used to assemble a n electricappliance configured as described in connection wit h thepreviousfigures.Furthermore, already produced acoustic panels 1 can bemodified to improve the noise damping properties in aspecificfrequencyband.Forexample,openings185 can beadded or modified with respect to its cross-section .Alternatively or in addition, a tube-like structure 185 maybe added ormodified appropriately.The embodiments shown in the Figures 1A to 6 as sta tedrepresent exemplary embodiments of the acoustic pan el, of theelectric appliance, and of the method; therefore, t hey do notconstitute a complete list of all embodiments accor ding tothe acoustic panel, the electric appliance, and the method.Actualacousticpanelsand electricappliancesand methodsmay vary from the embodiments shown in terms of spa tialarrangements, components, and materials, for exampl e. P2024,0671 WO N / P240069WO01 September22,2025 -25 - Reference Signs 1 acousticpanel 11 innerplate 12 outerplate 13 volume 14 filling material 15 mounting region 151 extension 17 rib structure 18 resonatorvolume 185 opening 187 tube-like structure 19 side wall 2 electricappliance 20 electricpowerdevice 21 tank 210 outerwall 22 reinforcementbar 220 surface ofreinforcementbar 221 gap 222 sealing and / ordamping material 225 blind bushing 31 clamp 32 nut 33 washer 34 screw S1 step S2 stepS3 step

Claims

P2024,0671 WO N / P240069WO01 September22,2025 -26 - Claims 1.An acousticpanel(1)foran electricappliance (2)with a tank(21),wherein- the acoustic panel (1) comprises an inner plate ( 11) facingthe tank (21) and an outer plate (12) facing away f rom thetank(21), -the acousticpanel(1)comprisesa rib structure (17)thatextends from the outer plate (12) to the inner plat e (11),- the rib structure (17) subdivides a volume (13) o f theacousticpanel(1)into a pluralityofchambers,- at least one of the chambers represents a resonat or volume(18)arranged between the innerplate (11)and the outer plate (12),- the acoustic panel (1) comprises an opening (185) coupledto the resonatorvolume (18),and- the acoustic panel (1) is configured to be mounte d to atleast one reinforcement bar (22) on an outer wall ( 210) ofthe tank (21) wherein the inner plate (21) of the a cousticpanel (1) is located closer to the outer wall (210) of thetank (21) than a surface (220) of the reinforcement bar (22)thatfacesawayfrom the tank(21). 2.The acousticpanelaccording to claim 1,wherein the acoustic panel (1) is configured to pro vide twospecificacousticdampening frequencybands. 3.The acousticpanelaccording to claim 1 or2,wherein the acoustic panel (1) comprises a tube-lik estructure (187)thatformsthe opening (185).

4. The acoustic panel according to any one of the p recedingclaims,P2024,0671 WO N / P240069WO01 September22,2025 -27 -wherein the opening (185) provides a gas exchange b etween theresonator volume (18) and an environment of the aco usticpanel(1).

5. The acoustic panel according to any one of claim s 1 to 3,wherein the opening (185) provides a gas exchange b etween theresonator volume (18) and a further volume within t heacousticpanel(1).

6. The acoustic panel according to any one of the p recedingclaims,wherein the acoustic panel (1) comprises a pluralit y ofresonator volumes (18), wherein at least some of th eresonator volumes (18) comprise an associated openi ng (185).7.The acousticpanelaccording to claim 6,wherein at least some of the openings (185) associa ted to theresonator volumes (18) provide a gas exchange betwe en theresonator volumes (18) and an environment of the ac ousticpanel. 8.The acousticpanelaccording to claim 6 or7,wherein at least some of the openings (185) associa ted to theresonator volumes (18) provide a gas exchange betwe enadjacent resonator volumes (18) of the acoustic pan el (1).

9. The acoustic panel according to any one of the p recedingclaims,wherein the resonator volume (18) is free from a fi llingmaterial. 10.The acousticpanelaccording to anyone ofthe preceding claims,P2024,0671 WO N / P240069WO01 September22,2025 -28 -wherein the resonator volume (18) includes a fillin g material(14)having a densityofatmost500 kg / m³. 11.The acousticpanelaccording to anyone ofthe preceding claims,wherein the resonator volume (18) includes a fillin g material(14)having a densityin a range from 0.5 g / cm³to 5 g / cm³.

12. An electric appliance comprising an acoustic pa nel (1)according to anyone ofthe preceding claimsand a tank(21),wherein the tank (21) comprises a plurality of rein forcementbars (22) arranged on an outer wall of the tank (21 ) andwherein the acoustic panel (1) is mounted to at lea st one ofthe reinforcement bars (22) wherein the inner plate of theacoustic panel (1) is located closer to the outer w all (210)of the tank (21) than a surface of the reinforcemen t bar (22)thatfacesawayfrom the tank(21). 13.The electricappliance according to claim 12,wherein the acoustic panel (1) is configured to gen erate anacoustic pressure that is in counter-phase to an ex citationpressure coming from the outer wall (210) of the ta nk (21)during operation ofthe electricappliance (2).

14. A method of assembling an electric appliance (2 ),comprising the steps of:a)providing an electricpowerdevice (20);b) forming a tank (21) that extends around the elec tric powerdevice (20), wherein the tank (21) comprises a plur ality ofreinforcement bars (22) arranged on an outer wall ( 210) ofthe tank(21);and c)mounting an acousticpanel(1)according to any one of claims1 to 10 to atleastone ofthe pluralityofP2024,0671 WO N / P240069WO01 September22,2025 -29 -reinforcement bars (22) wherein the inner plate (21 ) of theacoustic panel (1) is located closer to the outer w all (210)of the tank (21) than a surface (220) of the reinfo rcementbar(22)thatfacesawayfrom the tank(21). 15.The method according to claim 14,wherein the acoustic panel (1) comprises a resonato r volume(18), wherein at least one specific acoustic dampen ingfrequency band of the acoustic panel (1) is tuned b ymodifying atleastone resonatorparameter.

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