EP4718442A1

EP4718442A1 - Acoustic panel, electric appliance, and method of assembling an electric appliance

Info

Publication number: EP4718442A1
Application number: EP24202968.4A
Authority: EP
Inventors: Michal SWIATKOWSKI
Original assignee: Hitachi Energy Ltd
Current assignee: Hitachi Energy Ltd
Priority date: 2024-09-26
Filing date: 2024-09-26
Publication date: 2026-04-01
Also published as: WO2026068400A1

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

The present disclosure relates to an acoustic panel, an electric appliance, and to a method of assembling an electric appliance.
Electric appliances such as those used in energy distribution networks may produce noise during operation.
Embodiments of the disclosure relate to a way to dampen noise during operation of an electric appliance.
According to an embodiment of an acoustic panel, the acoustic panel is configured for an electric appliance with a tank, wherein the acoustic panel comprises an inner plate facing the tank and an outer plate facing away from the tank. A resonator volume is arranged between the inner plate and the outer plate. The acoustic panel comprises an opening coupled to the resonator volume. In particular, the acoustic panel is configured to be mounted to at least one reinforcement bar on an outer wall of the tank wherein the inner plate of the acoustic panel is located closer to the outer wall of the tank than a surface of the reinforcement bar that faces away from the tank.
The acoustic panel may be configured to absorb acoustic energy and to generate an acoustic pressure that is in counter-phase to an excitation pressure coming from the outer wall of the tank during operation of the electric appliance. Due to the resonant character, the acoustic panel can be specifically tuned to dampen one or more of the most critical frequency bands in the noise caused by the electric appliance.
The acoustic panel may be configured such that the reinforcement bars of the tank may be used to mount the acoustic panel. In contrast to conventional solutions, an additional supporting construction spaced apart from the tank can be dispensed with.
Further, the addition of the acoustic panel does not or at least not significantly increase the overall dimensions of the electric appliance.
Further, access to the electric appliance, for instance for maintenance purposes is facilitated compared to solutions where a supporting structure is mounted to the tank or / and to the ground and extends around the tank at a distance from the tank.
For example, the electric appliance comprises a liquid-immersed, in particular an oil-immersed power device. Thus, the tank receives the power device and the liquid.
For example, the power device comprises at least one of: a transformer, a phase shifter, a reactor, an inductor.
For example, the electric appliance is configured to be used in an energy distribution network.
For example, the inner plate and the outer plate of the acoustic panel extend in parallel or substantially in parallel to one another. For example, the acoustic panel comprises side walls extending obliquely or perpendicularly with respect to the inner plate and/or to the outer plate. The inner plate, the outer plate and the side walls taken together may define a volume that comprises one or more resonator volumes.
For example, the inner plate and/or the outer plate comprises or consists of a metal such as carbon steel, stainless steel, or aluminum. Alternatively or in addition, at least one of the inner plate or the outer plate may comprise or consist of a plastics material.
The reinforcement bars are not limited with respect to their cross-section. For example, the reinforcement bars may have a U-shaped, C-shaped, L-shaped, I-shaped, T-shaped or a rectangular cross-section.
Further, the electric appliance may comprise reinforcement bars that differ from one another with respect to a shape and/or the dimensions of the cross-section. For example, at least some of the reinforcement bars are arranged vertically or at least substantially vertically in space. Alternatively or in addition, horizontal reinforcement bars may be provided. Alternatively or in addition, oblique reinforcement bars may be provided, for instance diagonal reinforcement bars.
For example, the acoustic panel is configured to be mounted between reinforcement bars of the tank arranged on the outer wall of the tank, in particular between two directly adjacent reinforcement bars. Thus, a gap between adjacent reinforcement bars may be at least partly filled with the acoustic panel.
Alternatively, the acoustic panel may be mounted only on one side of the acoustic panel to a reinforcement bar. For example, this may apply at an edge or a corner of the tank. In this case, an additional construction may be used to mount the acoustic panel on the other side.
According to a further embodiment of the acoustic panel, the acoustic panel is configured to dampen at least one specific acoustic frequency band of the electric appliance. Thus, the acoustic panel may be specifically designed to efficiently dampen noise in a frequency band where the noise emission of the electric appliance during operation is particularly high. For example, typical dominant noise frequencies are around 100 Hz, 120 Hz, 300 Hz, or 400 Hz.
For example, parameters of the resonator volume and/or of the opening may be used to appropriately tune the dampening properties. Further, parameters affecting the stiffness of the acoustic panel and/or parameters of a filling material located in the resonator volume may be used to appropriately tune the dampening properties of the acoustic panel. The frequency tuning may be done during the production process or by an appropriate modification of already produced acoustic panels.
According to a further embodiment of the acoustic panel, the acoustic panel is configured to provide two specific acoustic dampening frequency bands. For example, a center-to-center distance between two adjacent acoustic dampening frequencies is at least 10 Hz or at least 20 Hz and/or at most 300 Hz or at most 200 Hz.
According to a further embodiment of the acoustic panel, the acoustic panel comprises a tube-like structure that forms the opening. For example, the tube-like structure may have a round cross-section. For example, a diameter of the cross-section is in a range from 5 mm to 300 mm. A height of the tube-like structure is in a range from 5 mm to 300 mm, for example. Here, the term "height" refers to the extent in a direction perpendicular to the cross-section.
For example, the acoustic panel comprises at least one tube-like structure and/or at most 200 tube-like structures or at most 100 tube-like structures or at most 50 tube-like structures.
Parameters of the tube-like structure such as the cross-section or the height may be used to appropriately tune the frequency response of the acoustic panel.
According to a further embodiment of the acoustic panel, the opening provides a gas exchange between the resonator volume and an environment of the acoustic panel. For example, the opening is located in the inner plate of the acoustic panel that faces the outer wall when mounted to the tank. Thus, the acoustic pressure in counter-phase with the excitation pressure may be directed from the acoustic panel towards the outer wall of the tank. However, the opening may also be located in the outer plate or in a side wall of the acoustic panel.
According to a further embodiment of the acoustic panel, the opening provides a gas exchange between the resonator volume and a further volume within the acoustic panel. In this case, the gas exchange from and into the resonator volume may occur within the volume of the acoustic panel. For example, the acoustic panel comprises at least two resonator volumes that are connected to one another via the opening.
According to a further embodiment of the acoustic panel, the acoustic panel comprises a plurality of resonator volumes, wherein at least some of the resonator volumes comprise an associated opening. For example, each of the resonator volumes is connected to at least one further resonator volume of the acoustic panel and/or to the environment.
According to a further embodiment of the acoustic panel, the acoustic panel comprises a rib structure that extends at least in regions from the outer plate to the inner plate. For example, the inner plate and the outer plate are mechanically connected to one another via the rib structure. This may significantly increase the stiffness of the acoustic panel. It has been found that the stiffness of the acoustic panel significantly affects the acoustic dampening properties.
In particular, the rib structure may be used to increase the stiffness of the acoustic panel without having to increase the thickness of the inner plate and/or the outer plate. This helps to keep the weight of the acoustic panel low.
The rib structure may subdivide the volume into a plurality of chambers, wherein at least one of the chambers represents a resonator volume. Thus, the volume of the resonator volume can be defined by an appropriate configuration of the rib structure. The rib structure may comprise one rib or a plurality of ribs that extends horizontally and/or one rib or a plurality of ribs that extends vertically in space when the acoustic panel is mounted to the tank.
The rib structure may be formed from the same material as the inner plate and/or the outer plate. The rib structure may comprise a metal, for instance. Alternatively, a material of the rib structure may be different from a material of the inner plate or the outer plate. The rib structure may comprise a plastics material, for instance.
According to a further embodiment of the acoustic panel, at least some of the openings associated to the resonator volumes provide a gas exchange between the resonator volume and an environment of the acoustic panel. For example, each of the resonator volumes communicates with the environment via an associated opening.
According to a further embodiment of the acoustic panel, at least some of the openings associated to the resonator volumes provide a gas exchange between adjacent resonator volumes of the acoustic panel. For example, each of the resonator volumes communicates with at least one further resonator volume via an associated opening.
The acoustic panel may also be air-tight, so that there is no or at least no significant gas exchange with the environment.
The acoustic panel may also comprise at least one opening towards the environment and at least one opening between two resonator volumes.
According to a further embodiment of the acoustic panel, the resonator volume is free from a filling material. In particular, some or all of the resonator volumes may be free from the filling material.
According to a further embodiment of the acoustic panel, the resonator volume includes a filling material. For example, the filling is provided as a mat or as a granular material. Additional energy dissipation may be achieved by means of the filling material.
According to a further embodiment of the acoustic panel, the filling material has a density of at most 500 kg/m³. For example, the density is in a range from 5 kg/m³ to 500 kg/m³. For example, mineral wool typically has a density in a range from 30 to 200 kg/m³. Alternatively or in addition the filling material may comprise an acoustic foam. A filling material having a low density helps to keep the weight of the acoustic panel low.
According to a further embodiment of the acoustic panel, the filling material has a density in a range from 0.5 g/cm³ to 5 g/cm³. Thus, the filling material has a comparably high density. For example, the filling material may comprise a plastics material such as polyvinyl chloride (PVC).
Alternatively or in addition, the filling material may comprise a granular rubber material such as granular EPDM (ethylene propylene diene monomer). It has turned out that a filling material having a comparably high density, in particular granular rubber, is suitable to efficiently dampen noise with frequencies occurring during operation of electric appliances with a power device immersed in a tank.
According to a further embodiment of the acoustic panel, a grain size of the filling material is in a range from 0.1 mm to 5 mm. Granular material with a grain size in this range has been proven to be particularly efficient for dampening noise in typical emission frequency bands of electric appliances. However, non-granular filling material may also be used.
According to a further embodiment of the acoustic panel, at least one of the inner plate or the outer plate has a thickness in a range from 2 mm to 6 mm. It has turned out that an efficient noise reduction can be obtained while the weight of the acoustic panel can be kept low at the same time.
According to a further embodiment of the acoustic panel, a thickness of the acoustic panel is in a range from 10 mm to 300 mm. The thickness refers to the extent of the acoustic panel in a direction perpendicular to the outer plate of the acoustic panel. In particular, the thickness of the acoustic panel may be used to adapt the efficiency of noise dampening and/or the spectral response of the acoustic panel. For example, the thickness of the acoustic panel may be used to define the volume of the resonator volume.
According to a further embodiment of the acoustic panel, the acoustic panel comprises a mounting region for mounting the acoustic panel. In particular, the mounting region laterally projects beyond the inner plate. For example, the acoustic panel comprises two mounting regions extending along two opposite edges of the acoustic panel. For example, the mounting region is configured to receive a mechanical connector such as a screw, a bolt, or a clamp.
For example, the mounting region is formed by a part of the outer plate that laterally projects beyond the inner plate.
Alternatively or in addition, the mounting region may be formed by an extension attached to the outer plate.
Further, an electric appliance is specified. In particular, the electric appliance comprises at least one acoustic panel as described above and a tank.
According to an embodiment of the electric appliance, the tank comprises a plurality of reinforcement bars arranged on an outer wall of the tank wherein the acoustic panel is mounted to at least one of the reinforcement bars wherein the inner plate of the acoustic panel is located closer to the outer wall of the tank than a surface of the reinforcement bar that faces away from the tank.
For example, the acoustic panel may be mounted between two reinforcement bars of the plurality of reinforcement bars, in particular between two directly adjacent reinforcement bars.
According to a further embodiment of the electric appliance, the acoustic panel is configured to generate an acoustic pressure that is in counter-phase to an excitation pressure coming from the outer wall of the tank during operation of the electric appliance. Thus, the acoustic panel may be designed as a resonant element to specifically dampen noise in one or more acoustic frequency band(s) that dominates in the noise spectrum of the electric appliance.
For example, the acoustic panel extends into a gap between two directly adjacent reinforcement bars in a top view onto the electric appliance. Alternatively or in addition, an acoustic panel of the electric appliance may be mounted to only one of the reinforcement bars as described above.
According to a further embodiment of the electric appliance, the inner plate is arranged completely within a gap between two adjacent reinforcement bars in a top view onto the electric appliance. Thus, the space between the reinforcement bars can be used, at least in part, for the acoustic panel.
For example, all gaps between two adjacent reinforcement bars are at least partly filled with one acoustic panel.
According to at least one embodiment of the electric appliance, the acoustic panel comprises a mounting region that overlaps with one of the reinforcement bars. In particular, a sealing and/or damping material may be arranged between the mounting region and the reinforcement bar. The sealing and/or damping material may be used to reduce a transfer of vibrations of the outer wall of the tank to the acoustic panel via the mounting region, and/or to seal a closed area created between the acoustic panels, the reinforcement bars, and the outer wall of the tank.
For example, the sealing and/or damping material comprises a rubber material or cork rubber. In this area also other damping systems can be used, for example single or stacked spring washers.
According to at least one embodiment of the electric appliance, a distance between a support structure of the acoustic panel and the tank is sealed using a sealing system. For example, the sealing system comprises cork, rubber or another sealing material. For example, a thickness of the sealing system is in a range from 1 mm to 500 mm.
According to at least one embodiment of the electric appliance, a distance between the inner plate of the acoustic panel and the outer wall of the tank is in a range from 0 mm to 500 mm. Thus, the inner plate may directly adjoin the outer wall of the tank. Alternatively, the inner plate may be spaced apart from the outer wall of the tank. For example, the distance between the inner plate of the acoustic panel and the outer wall of the tank is at least 1 mm or at least 5 mm or at least 10 mm.
Further, a method of assembling an electric appliance is specified.
According to an embodiment of the method, the method comprises the steps of providing an electric power device, the step of forming a tank that extends around the electric power device wherein the tank comprises a plurality of reinforcement bars arranged on an outer wall of the tank and the step of mounting an acoustic panel to at least one of the plurality of reinforcement bars wherein the inner plate of the acoustic panel is located closer to the outer wall of the tank than a surface of the reinforcement bar that faces away from the tank. The method steps can be performed in the indicated order. However, this is not necessary.
According to an embodiment of the method, the acoustic panel comprises a resonator volume, wherein at least one specific acoustic dampening frequency band of the acoustic panel is tuned by modifying at least one resonator parameter. In particular, this may be done in already produced or even in already mounted acoustic panels. For example, the frequency tuning may be obtained by adding an opening and/or by changing a size of an existing opening and/or by adding or modifying a tube-like structure.
According to a further embodiment of the method, the step of mounting the acoustic panel is performed prior to the step of forming the tank. Thus, the acoustic panel can be provided in a pre-assembled manner together with a part of the tank. In conventional approaches, in contrast, the tank is formed first and the sound panels are attached to a supporting structure that extends around the finished tank at a minimum distance from the tank which is typically about 500 mm.
The method is particularly suitable for the electric appliance described above. Features and advantages described in connection with the acoustic panel or the electric appliance can therefore be used for the method and vice versa.
Features described in connection with at least one embodiment may be combined with other features described in connection with other embodiments unless they are contradictory.
The accompanying figures are included to provide a further understanding. In the figures, elements of the same structure and/or functionality may be referenced by the same reference signs. It is to be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.
In the Figures:

Figure 1A shows a schematic sectional view of an electric appliance with acoustic panels according to an embodiment,
Figure 1B shows a schematic side view of an electric appliance with acoustic panels according to an embodiment,
Figure 2A shows a schematic sectional view of an electric appliance with acoustic panels according to an embodiment,
Figure 2B shows a schematic side view of an electric appliance with acoustic panels according to an embodiment,
Figure 3A shows a perspective view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 3B shows a sectional view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 4A shows a perspective view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 4B shows a perspective view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 5A shows a schematic side view of an electric appliance with acoustic panels according to an embodiment,
Figure 5B shows a further schematic side view of an electric appliance with acoustic panels according to an embodiment,
Figure 6 shows a schematic representation of a method according to an embodiment,
Figure 7 shows simulation results of a response of an embodiment of an acoustic panel as a function of the frequency.

While the disclosure is amendable to various modifications and alternative forms, specifics thereof have been shown by way of example in the figures and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure defined by the appended claims.
In the embodiment shown in Figures 1A and 1B, three different examples of an acoustic panel 1 are illustrated, wherein each acoustic panel 1 configured for an electric appliance 2 with a tank 21. The acoustic panel 1 comprises an inner plate 11 facing the tank 21 and an outer plate 12 facing away from the tank 21.
In the acoustic panel 1 on the left, a volume 13 between the inner plate 11 and the outer plate 12 represents a resonator volume 18. The acoustic panel 1 comprises an opening 185 coupled to the resonator volume 18. 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. The inner plate 11 of the acoustic panel 1 is located closer to the outer wall 210 of the tank 21 than a surface of the reinforcement bar 22 that faces away from the tank 21.
The examples of acoustic panels 1 in the middle and on the right differ from the example on the left in that the volume 13 is subdivided in a plurality of resonator volumes 18. The volume 13 of the acoustic panel is subdivided in the vertical direction, whereas the volume of the acoustic panel on the right is subdivided both vertically and horizontally in space when mounted to the tank 21.
Each resonator volume 18 comprises an opening 185. In the embodiment of Figures 1A and 1B, the openings 185 provide an air exchange between the resonator volumes 18 and the environment. The openings 185 are arranged on the inner plate 11 of the acoustic panel 1.
The acoustic panels 1 are configured to absorb acoustic energy and to generate an acoustic pressure that is in counter-phase to an excitation pressure coming from the outer wall 210 of the tank 21 during operation of the electric appliance 2.
The resonator volumes 18 are separated from one another via a rib structure 17 that extends from the inner plate 11 to the outer plate 12.
The opening 185 is formed by a tube-like structure 187. For example, the tube-like structure may have a round cross-section. For example, a diameter of the cross-section is in a range from 5 mm to 300 mm. A height of the tube-like structure is in a range from 5 mm to 300 mm, for example.
Parameters of the tube-like structure 187 such as the cross-section or the height and/or the volume of the resonator volumes 18 may be used to appropriately tune the frequency response of the acoustic panel in such a way that the acoustic panel 1 efficiently dampens noise in a frequency band where the noise emission of the electric appliance 2 during operation is particularly high.
The number of tube-like structures may be varied in wide ranges. For example, the acoustic panel 1 comprises at least one tube-like structure 187 and/or at most 200 tube-like structures 187 or at most 100 tube-like structures 187 or at most 50 tube-like structures 187.
The rib structure 17 that separates the resonator volumes 18 from one another extends from the outer plate 12 to the inner plate 11. Thus, the volume of the individual resonator volumes 18 may be adapted by the configuration of the rib structure 17. The rib structure 17 may be formed from the same material as the inner plate 11 and/or the outer plate 12 or from a different material.
Further, the mechanical connection between in the inner plate 11 and the outer plate 12 via the rib structure 17 increases the stiffness of the acoustic panel 1. This may result in minimized low frequency vibrations of the outer plate 12.
In the embodiment shown in Figures 1A and 1B, the acoustic panels 1 are each mounted in a gap 221 between two adjacent reinforcement bars 22. Thus, the gap 221 is at least partly filled with the acoustic panel 1 so that this space can be used for noise dampening.
Different ways for mounting the acoustic panel 1 to the reinforcement bars 22 will be described in connection with Figures 3A, 3B, 4A, and 4B.
Unlike the schematic representations of Figures 1A and 1B, the acoustic panel 1 can also be mounted to only one reinforcement bar 22. For example, this may be the case at an edge or a corner of the tank 21. Here, the side of the acoustic panel opposite to the reinforcement bar 22 may be connected to the tank 21 or to another acoustic panel 1 by means of a dedicated support structure.
During operation of the electric appliance 2, the acoustic panels 1 dampen the noise of an electric power device 20 of the electric appliance 2. For example, the electronic power device 20 may comprise or consist of a transformer, a phase shifter, a reactor, or an inductor.
In particular, almost the complete outer walls 210 of the tank 21 may be covered by acoustic panels 1.
By tuning the resonant properties, the acoustic panel 1 can be specifically designed such that the noise reduction is tuned to one or more of the particular frequency bands of the noise emitted by the electric appliance 2 during operation. The acoustic frequency bands are specific to the electric appliance 2. In particular, these frequencies may also depend on the net frequency of the energy distribution network.
For example, typical dominant noise frequencies are around 100 Hz, 120 Hz, 300 Hz, or 400 Hz.
Optionally, the resonator volumes 18 may be filled with a filling material 14. The filling material 14 may help to obtain a further noise reduction. The filling material 14 may have a comparably low density. For example, the density of the filling material is in a range from 5 kg/m³ to 500 kg/m³. For example, a mineral wool or an acoustic foam may be used.
Alternatively, a comparably dense filling material 14 may be used such as a plastics material like PVC.
Alternatively, the filling material may comprise a granular rubber material such as granular EPDM (ethylene propylene diene monomer).
This material can be provided as recycling material, for example.
For example, a grain size of the filling material 14 is in a range from 0.1 mm to 5 mm.
The inner plate 11 and/or the outer plate 12 may have a thickness in a range from 2 mm to 6 mm. As the thickness of the inner plate 11 and the outer plate 12 affects the stiffness of the acoustic panel 1, the thickness of the inner plate 11 and/or the outer plate 12 may also be used to tune the acoustic frequency response.
A thickness of the acoustic panel 1 may be in a range from 10 mm to 300 mm, for example.
In the embodiment of Figures 1A and 1B, the inner plate 11 of the acoustic panel 1 is spaced apart from the outer wall 210 of the tank 21. However, the inner plate 11 may also directly adjoin the tank 21. For example, the distance between the inner plate 11 of the acoustic panel 1 and the outer plate 210 of the tank 21 is in a range from 0 mm to 500 mm.
A distance between a support structure of the acoustic panel 1 and the tank 21 may be sealed using a sealing system. For example, the sealing system comprises cork, rubber or another sealing material. For example, a thickness of the sealing system is in a range from 1 mm to 500 mm.
For example, the inner plate 11 and/or the outer plate 12 comprises a metal such as carbon steel, stainless steel or aluminium, or a plastics material.
The resonant response characteristics of the described acoustic panels 1 are illustrated in Figure 7. Figure 7 depicts simulation results of a frequency response curve of an acoustic panel, where an air pressure p between the acoustic panel and the outer wall of the tank is illustrated for a vibration of the outer wall of the tank with an amplitude of 1 mm. Due to the resonant behavior of the acoustic panel, the curve has pronounced minima at frequencies of 100 Hz, 143 Hz, and 320 Hz.
Thus, two or more frequency bands may be efficiently dampened by appropriately configuring the resonator volume(s) of the acoustic panel 1. As described above, the position of these minima can be tuned by appropriately changing the parameters of the acoustic panel 1.
The embodiment illustrated in Figures 2A and 2B substantially corresponds to the embodiment depicted in Figures 1A and 1B. In departure therefrom, the resonator volumes 18 of the acoustic panels 1 are connected to one another via openings 185 formed by tube-like structures 187. In the acoustic panel 1 depicted on the left, resonator volumes 18 arranged side by side in the horizontal direction are connected to one another. Exemplarily, the acoustic panel 1 comprises twelve resonator volumes 18.
In the acoustic panel 1 depicted on the right and in the middle, resonator volumes 18 arranged one above the other in the vertical direction are connected to one another. Exemplarily, these acoustic panels 1 comprises six resonator volumes 18.
In these embodiments according to Figures 2A and 2B, the gas exchange occurs within the acoustic panels 1. Thus, the acoustic panels may be air-tight or substantially air-tight.
However, one or more of the resonator volumes 18 may be connected to the environment as described in connection with Figures 1A and 1B.
Figures 3A and 3B illustrate an embodiment of an acoustic panel 1 mounted to a T-shaped reinforcement bar 22 on an outer wall 210 of a tank 21 of an electric appliance 2. The acoustic panel 1 comprises an inner plate 11 and an outer plate 12 extending in parallel to one another. A sidewall 19 is arranged between the inner plate 11 and the outer plate 12. As described in connection with Figures 1A, 1B, 2A, and 2B, the volume 13 comprises at least one resonator volume 18 with an opening 185. This is not explicitly shown in Figures 3A and 3B for the sake of simplicity.
The acoustic panel 1 comprises a mounting region 15. The mounting region 15 laterally extends beyond the inner plate 11 and is configured to overlap with the reinforcement bar 22 when mounted to the outer wall 210 of the tank 21. The mounting region 15 may be formed by a part of the outer plate 12. Alternatively, the mounting region 15 may also be formed by a separate element attached to the outer plate 12 as illustrated in Figure 4A, for instance.
The mounting region 15 and means for mechanically mounting the acoustic panel 1 to the reinforcement bars 22 may be adapted to the cross-section of the reinforcement bars 22. In Figure 3A, the reinforcement bars 22 have a T-shaped cross-section. However, other geometries may also be used for the reinforcement bars, for example a U-shaped or substantially rectangular cross-section of the reinforcement bars 22. Other cross-sections such as C-shaped, L-shaped, or I-shaped may also be used.
The mounting region 15 overlaps with the reinforcement bar 22. The mechanical connection between the acoustic panel 1 and the reinforcement bar 22 is obtained via a clamp 31 that directly adjoins the reinforcement bar 22 and is secured to the acoustic panel 1 via a washer 33 and a nut 32.
A sealing and/or damping material 222 is arranged between the mounting region 15 of the acoustic panel and the surface 220 of the reinforcement bar 22, for example the damping material 222 comprises a rubber.
In the embodiments of Figures 4A and 4B, the reinforcement bars 22 have a U-shaped cross-section. In the embodiment of Figure 4A, the mounting region 15 is formed by an extension 151 attached to the outer plate 12 of the acoustic panel. The extension 151 has a hole or a cutout to receive a screw 34 extending into a blind bushing 225 of the reinforcement bar 22.
The embodiment of Figure 4B substantially corresponds to the embodiment of Figure 4A. However, the mounting region 15 is formed by a portion of the outer plate 12 that overlaps with the reinforcement bar 22.
Figures 5A and 5B illustrate two side views of an electric appliance 2 with a tank 21 and a plurality of acoustic panels 1 that may be configured as described in the previous figures. Figure 5B further schematically illustrates the electric power device 20 immersed in a liquid within tank 21.
Figures 5A and 5B illustrate that almost the entire surface of the outer wall 210 of the tank 21 may be covered with acoustic panels 1 so that an efficient noise reduction can be obtained. Compared to conventional solutions, the acoustic panels 1 do not significantly increase the size of the electric appliance 2. Further, access to the tank 21 is facilitated.
Figure 6 illustrates an embodiment of a method of assembling an electric appliance. For better understanding, structural features described in connection with the previous figures are used even though these elements are not explicitly shown in Figure 6.
In a step S1, an electric power device 20 is provided. In a step S2, a tank is formed that extends around the electric power device. The tank 21 comprises a plurality of reinforcement bars 22 arranged on an outer wall 210 of the tank 21. In a step S3, an acoustic panel 1 is mounted to at least one of the reinforcement bars 22 wherein the inner plate of the acoustic panel 1 is located closer to the outer wall of the tank 21 than a surface 220 of the reinforcement bar 22 that faces away from the tank.
The method can be performed in the indicated order.
However, this is not necessarily required. Rather, at least part of step S3 may be performed prior to step S2. For example, at least one acoustic panel 1 may be preassembled to a part of the tank. Thus, parts of the tank may be provided with an acoustic panel before the tank 21 has been completed.
This may help to facilitate the assembling process of the electric appliance 2.
In particular, the method can be used to assemble an electric appliance configured as described in connection with the previous figures.
Furthermore, already produced acoustic panels 1 can be modified to improve the noise damping properties in a specific frequency band. For example, openings 185 can be added or modified with respect to its cross-section. Alternatively or in addition, a tube-like structure 185 may be added or modified appropriately.
The embodiments shown in the Figures 1A to 6 as stated represent exemplary embodiments of the acoustic panel, of the electric appliance, and of the method; therefore, they do not constitute a complete list of all embodiments according to the acoustic panel, the electric appliance, and the method. Actual acoustic panels and electric appliances and methods may vary from the embodiments shown in terms of spatial arrangements, components, and materials, for example.

Reference Signs

1: acoustic panel
11: inner plate
12: outer plate
13: volume
14: filling material
15: mounting region
151: extension
17: rib structure
18: resonator volume
185: opening
187: tube-like structure
19: side wall
2: electric appliance
20: electric power device
21: tank
210: outer wall
22: reinforcement bar
220: surface of reinforcement bar
221: gap
222: sealing and/or damping material
225: blind bushing
31: clamp
32: nut
33: washer
34: screw
S1: step
S2: step
S3: step

Claims

An acoustic panel (1) for an electric appliance (2) with a tank (21), 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).
The acoustic panel according to claim 1,
wherein the acoustic panel (1) is configured to provide two specific acoustic dampening frequency bands.
The acoustic panel according to claim 1 or 2,
wherein the acoustic panel (1) comprises a tube-like structure (187) that forms the opening (185).
The acoustic panel according to any one of the preceding claims,
wherein the opening (185) provides a gas exchange between the resonator volume (18) and an environment of the acoustic panel (1).
The acoustic panel according to any one of claims 1 to 3, wherein the opening (185) provides a gas exchange between the resonator volume (18) and a further volume within the acoustic panel (1).
The acoustic panel according to any one of the preceding claims,
wherein the acoustic panel (1) comprises a plurality of resonator volumes (18), wherein at least some of the resonator volumes (18) comprise an associated opening (185).
The acoustic panel according to claim 6,
wherein at least some of the openings (185) associated to the resonator volumes (18) provide a gas exchange between the resonator volumes (18) and an environment of the acoustic panel.
The acoustic panel according to claim 6 or 7,
wherein at least some of the openings (185) associated to the resonator volumes (18) provide a gas exchange between adjacent resonator volumes (18) of the acoustic panel (1).
The acoustic panel according to any one of the preceding claims,
wherein the resonator volume (18) is free from a filling material.
The acoustic panel according to any one of the preceding claims,
wherein the resonator volume (18) includes a filling material (14) having a density of at most 500 kg/m³.
The acoustic panel according to any one of the preceding claims,
wherein the resonator volume (18) includes a filling material (14) having a density in a range from 0.5 g/cm³ to 5 g/cm³.
An electric appliance comprising an acoustic panel (1) according to any one of the preceding claims and a tank (21), wherein the tank (21) comprises a plurality of reinforcement bars (22) arranged on an outer wall of the tank (21) and wherein the acoustic panel (1) is mounted to at least one of the reinforcement bars (22) wherein the inner plate of the acoustic panel (1) is located closer to the outer wall (210) of the tank (21) than a surface of the reinforcement bar (22) that faces away from the tank (21).
The electric appliance according to claim 12,
wherein the acoustic panel (1) is configured to generate an acoustic pressure that is in counter-phase to an excitation pressure coming from the outer wall (210) of the tank (21) during operation of the electric appliance (2).
A method of assembling an electric appliance (2), comprising the steps of:
a) providing an electric power device (20);

b) forming a tank (21) that extends around the electric power device (20), wherein the tank (21) comprises a plurality of reinforcement bars (22) arranged on an outer wall (210) of the tank (21); and

c) mounting an acoustic panel (1) to at least one of the plurality of reinforcement bars (22) 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).
The method according to claim 14,
wherein the acoustic panel (1) comprises a resonator volume (18), wherein at least one specific acoustic dampening frequency band of the acoustic panel (1) is tuned by modifying at least one resonator parameter.