EP4718483A1

EP4718483A1 - Acoustic panel, electric appliance and method of assembling an electric appliance

Info

Publication number: EP4718483A1
Application number: EP24202971.8A
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: WO2026068366A1

Abstract

An acoustic panel (1) for an electric appliance (2) with a tank (21) is specified, wherein
- the acoustic panel comprises an inner plate (11) facing the tank (21) and an outer plate facing away from the tank (21),
- a volume (13) between the inner plate (11) and the outer plate (12) is filled with a filling material (14),
- 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 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), and
- the acoustic panel (1) comprises a frequency tuning element (4) configured to tune a specific acoustic dampening frequency band of the acoustic panel (1).

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 volume between the inner plate and the outer plate is filled with a filling material. The acoustic panel comprises a frequency tuning element configured to tune a specific acoustic dampening frequency band of the acoustic panel. For example, 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 noise reduction may result from the dissipation of acoustic energy in the volume, in particular in the filling material as the filling material may be stimulated to vibrate by the inner plate and/or the outer plate. These plates may vibrate with low order forms and therefore with high acoustic efficiency. In particular, the vibration of the inner plate and/or the outer plate may result from pressure waves in the air between the outer wall of the tank and the acoustic panel.
By means of the frequency tuning element, the acoustic panel may configured in such a way that it dampens a specific acoustic frequency band of a particular electric appliance. In particular, the vibration modes may be changed in a targeted manner by means of the frequency tuning element, so that the acoustic panel has the highest noise reduction in a predetermined frequency range. Thus, during its production the acoustic panel may be specifically adapted by means of the frequency tuning element 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.
Further, parameters affecting the stiffness of the acoustic panel and/or parameters of the filling material may be used to appropriately tune the dampening properties of the acoustic panel.
In particular, a high dampening efficiency can be obtained with acoustic panels that have a low weight compared to conventional solutions.
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 the volume.
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 frequency tuning element is located within the volume. Thus, the frequency tuning element does not increase the size of the acoustic panel. For example, the frequency tuning element is arranged on a side of the outer plate that faces the inner plate or on a side of the inner plate that faces the outer plate.
According to a further embodiment of the acoustic panel, the frequency tuning element comprises a concentrated mass. Thus, the concentrated mass may act as a frequency tuning element that changes the vibration modes and tunes them to a predetermined frequency range by locally increasing the mass of the acoustic panel in a targeted manner. For example, a density of the concentrated mass is at least by 50 % larger than a density of the filling material. For example, the concentrated mass comprises a metal. In particular, the mass and/or the position of the concentrated mass and/or the number of concentrated masses may be used to appropriately change the vibration modes.
For example, a lateral extent of the concentrated mass is at most 50 % of a lateral extent of the acoustic panel when seen along the same direction. The term lateral extent in particular means the extent along a direction that extends in parallel to the inner plate and/or the outer plate. In particular, the lateral extent of the concentrated mass is small compared to a width of the acoustic panel. If the acoustic panel has a substantially rectangular shape, the width refers to the lateral extent along the shorter edge.
According to a further embodiment of the acoustic panel, a mass of the concentrated mass is in a range from 0.2 kg to 10 kg. It has turned out that concentrated masses in this range are particularly suitable to specifically tune the acoustic dampening frequency band of the acoustic panel.
For example, the acoustic panel comprises at least one or at least two and/or at most 20 or at most 10 concentrated masses as frequency tuning elements.
According to a further embodiment of the acoustic panel, the frequency tuning element comprises a stiffener configured to stiffen the inner plate or the outer plate. It has been found that the stiffness of the acoustic panel significantly affects the acoustic dampening properties. Thus, the stiffener may act as a frequency tuning element that changes the vibration modes of the acoustic panel due to the increased stiffness of the acoustic panel. In particular, the stiffener 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.
For example, the stiffener is attached to the inner plate or to the outer plate. For example, the stiffener is spaced apart from the other one of the inner plate and the outer plate. Alternatively, the stiffener may extend from the inner plate to the outer plate at least in regions.
According to a further embodiment of the acoustic panel, the stiffener extends over at least 70 % of the acoustic panel along a lateral direction. For example, a lateral extent of the stiffener is at most 70 % of a width of the acoustic pane.
According to a further embodiment of the acoustic panel, the stiffener is formed from the same material as the inner plate or the outer plate. The stiffener may comprise a metal, for instance.
According to a further embodiment of the acoustic panel, a material of the stiffener is different from a material of the inner plate or the outer plate. The stiffener may comprise a plastics material, for instance.
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 or 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.
According to a further embodiment of the acoustic panel, a density of the filling material is 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 density of the filling material 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 reduce the weight of the acoustic panel.
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.
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.
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 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 3 shows a perspective 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 sectional view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 5A shows a perspective view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 5B shows a perspective view of a detail of an electric appliance with an acoustic panel according to an embodiment,
Figure 6A shows a schematic side view of an electric appliance with acoustic panels according to an embodiment,
Figure 6B shows a further schematic side view of an electric appliance with acoustic panels according to an embodiment,
Figure 7 shows a schematic representation of a method according to an embodiment.

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, an acoustic panel 1 is 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. A volume 13 between the inner plate 11 and the outer plate 12 is filled with a filling material 14. 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 acoustic panel 1 comprises a plurality of frequency tuning elements 4 configured to tune a specific acoustic dampening frequency band of the acoustic panel 1. In the embodiment shown in Figures 1A and 1B, the frequency tuning elements 4 are formed as concentrated masses 41. During production of the acoustic panels 1, the dampening frequency band of the acoustic panel 1 may be adapted to the frequency where the noise emission of the electric appliance 2 during operation is particularly high. For example, a dominant noise frequency may be around 100 Hz, 120 Hz, 300 Hz, or 400 Hz.
Exemplarily, the acoustic panel 1 comprises three concentrated masses 41. However, the number of frequency tuning elements 4 may be varied in wide ranges, for example in a range from 1 to 20.
The frequency tuning elements 4 are arranged in the volume 13, so that the frequency tuning elements 4 do not increase the size of the acoustic panels 1.
A lateral extent e1 of the concentrated mass 41 is small compared to a lateral extent of the acoustic panel 1 when seen along the same direction. For example, the lateral extent e1 of the concentrated mass 41 is at most 50 % of a width w1 of the acoustic panel 1. Due to their comparably small lateral extent e1, the concentrated masses 41 can be positioned in regions of the acoustic panel 1 where the frequency tuning is particularly efficient.
The concentrated masses 41 may be formed from a material having a high density, for example from a metal.
In a side view, the concentrated masses 41 have a rectangular cross-section, for instance a square cross-section, but other shapes may also be used.
For example, a mass of the concentrated masses 41 is in a range from 0.2 kg to 10 kg. The acoustic panel 1 may also comprise concentrated masses 41 that differ from one another with respect to the weight and/or the lateral extent.
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 4A, 4B, 5A, and 5B.
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.
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 2. Here, the side of the acoustic panel opposite to the reinforcement bar 22 may be connected to the tank 2 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 in 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.
In particular, the noise reduction results from the dissipation of acoustic energy in the volume 13, in particular in the filling material 14 as the filling material is stimulated to vibrate by the inner plate 11 and/or the outer plate 12. These plates may vibrate with low order forms and therefore with high acoustic efficiency. In particular, the vibration of the inner plate 11 and/or the outer plate 12 may result from pressure waves in the air between the outer wall 210 of the tank and the acoustic panel 1.
As described above, the acoustic panel 1 can be specifically designed such that the noise reduction is tuned to a particular frequency band 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 or 300 Hz and 400 Hz.
In addition to the frequency tuning elements 4, other parameters of the acoustic panel 1 may be appropriately set to obtain an efficient noise reduction. For example, the filling material 14 has significant impact on the efficiency of the noise reduction within a specific frequency band. For example, the filling material 14 has a density in a range from 0.5 g/cm³ to 5 g/cm³. Thus, the filling material has as comparably high density. For example, 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.
Alternatively, a filling material 14 having a lower density may be used. 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.
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.
For example, the inner plate 11 and/or the outer plate 12 comprises a metal such as carbon steel, stainless steel or aluminum or a plastics material.
The embodiment illustrated in Figures 2A and 2B substantially corresponds to the embodiment of Figures 1A and 1B.
In contrast, the frequency tuning elements 4 are formed by stiffeners 42 arranged on the outer plate 12 of the acoustic panel 1. Alternatively or in addition, the inner plate 11 may be provided with one ore more frequency tuning elements 4.
The stiffeners 42 extend over at least 70 % of a lateral extent of the acoustic panel 1. For example, a lateral extent e2 of the stiffener is at most 70 % of a width w1 of the acoustic panel.
It is noted that concentrated masses 41 and stiffeners 42 may also be combined in an acoustic panel. For example, the acoustic panel 1 shown in Figures 1A and 1B may also comprise stiffeners 42 as illustrated in Figures 2A and 2B.
Figure 3 illustrates details of an embodiment of an acoustic panel 1 to be mounted to reinforcement bars 22 on an outer wall 210 of the 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 illustrated in Figure 3 a volume 13 between the inner plate 11 and the outer plate 12 may be subdivided into a plurality of chambers 16.
For example, the chambers 16 may help to maintain a homogenous distribution of the filling material 14 within the volume 13 over time. However, these chambers 16 are not necessarily required.
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. In the embodiment of Figure 3 the mounting region 15 is 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 5A, 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 3, 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.
Figures 4A and 4B illustrate an embodiment of an acoustic panel 1 mounted to a T-shaped reinforcement bar 22. As described in connection with Figure 3, 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 comprises a rubber. The frequency tuning elements 4 may be configured as described in connection with Figures 1A and 1B or Figures 2A and 2B, for example and are not explicitly depicted for easier representation.
In the embodiments of Figures 5A and 5B, 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 frequency tuning elements 4 may be configured as described in connection with Figures 1A and 1B or Figures 2A and 2B, for example and are not explicitly depicted for easier representation.
The embodiment of Figure 5B substantially corresponds to the embodiment of Figure 5A. However, the mounting region 15 is formed by a portion of the outer plate 12 that overlaps with the reinforcement bar 22.
Figures 6A and 6B 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 6A and 6B 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. The frequency tuning elements 4 may be configured as described in connection with Figures 1A and 1B or Figures 2A and 2B, for example and are not explicitly depicted for easier representation.
Figure 7 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 7.
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 plurality of 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.
In particular, the method can be used to assemble an electric appliance 2 configured as described in connection with the previous figures.
The embodiments shown in the Figures 1A to 7 as stated represent exemplary embodiments of the acoustic panel, of the electric appliance 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
16: chamber
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
4: frequency tuning element
41: concentrated mass
42: stiffener
S1: step
S2: step
S3: step
w1: width
e1: lateral extent of concentrated mass
e2: lateral extent of stiffener

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 volume (13) between the inner plate (11) and the outer plate (12) is filled with a filling material (14),

- 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), and

- the acoustic panel (1) comprises a frequency tuning element (4) configured to tune a specific acoustic dampening frequency band of the acoustic panel (1).
The acoustic panel according to claim 1,
wherein the frequency tuning element (4) is located within the volume (13).
The acoustic panel according to claim 1 or 2,
wherein the frequency tuning element (4) comprises a concentrated mass (41), wherein a density of the concentrated mass is at least by 50 % larger than a density of the filling material (14) and wherein a lateral extent (e1) of the concentrated mass is at most 50 % of a lateral extent of the acoustic panel when seen along the same direction.
The acoustic panel according to claim 3,
wherein a mass of the concentrated mass is in a range from 0.2 kg to 10 kg.
The acoustic panel according to any one of the preceding claims,
wherein the frequency tuning element (4) comprises a stiffener (42) configured to stiffen the inner plate (11) or the outer plate (12).
The acoustic panel according to claim 5,
wherein the stiffener (42) extends over at least 70 % of the acoustic panel (1) along a lateral direction.
The acoustic panel according to claim 5 or 6,
wherein the stiffener (42) is formed from the same material as the inner plate (11) or the outer plate (12).
The acoustic panel according to claim 5 or 6,
wherein a material of the stiffener (42) is different from a material of the inner plate (11) or the outer plate (12).
The acoustic panel according to any one of the preceding claims,
wherein the acoustic panel (1) comprises a mounting region (15) for mounting the acoustic panel (1), wherein the mounting region (15) laterally projects beyond the inner plate (11).
An electric appliance (2) 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 (10) 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 (11) 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 electric appliance according to claim 10,
wherein the acoustic panel (1) comprises a mounting region (15) that overlaps with one of the reinforcement bars (22), wherein a sealing and/or damping material (222) is arranged between the mounting region (15) and the reinforcement bar (22) .
The electric appliance according to claim 10 or 11, wherein a distance between the inner plate (11) of the acoustic panel (1) and the outer wall (210) of the tank (21) is in a range from 0 mm to 500 mm.
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 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 13,
wherein step c) is performed prior to step b).
The method according to claim 13 or 14,
wherein an electric appliance (2) according to any one of claims 10 to 12 is produced.