CN115886634A

CN115886634A - Household appliance with muffler device

Info

Publication number: CN115886634A
Application number: CN202210915249.XA
Authority: CN
Inventors: A.内扎米; T.埃纳
Original assignee: Vorwerk and Co Interholding GmbH
Current assignee: Vorwerk and Co Interholding GmbH
Priority date: 2021-08-03
Filing date: 2022-08-01
Publication date: 2023-04-04
Also published as: EP4129134A1; US20230045149A1

Abstract

The invention relates to a household appliance (1), in particular a floor treatment appliance, comprising an appliance housing (2), a fan (3) arranged in the appliance housing, an outlet opening (4) formed in the appliance housing downstream of the fan (3) in the flow direction, a flow channel (5) connecting the outlet opening (4) to the fan (3) in a fluid-conducting manner, and a sound-damping device (6) associated with the flow channel for damping sound generated by the operation of the household appliance (1). In order to advantageously improve the sound damping device (6), it is proposed that the sound damping device (6) has a plurality of sound-absorbing wall elements which together form at least one section of the flow duct (5), wherein the wall elements have wall surfaces (10) which are curved relative to the longitudinal extent of the flow duct (5) and are positioned relative to one another such that the flow path (11) formed between the mutually opposite wall surfaces extends in a curved manner.

Description

Household appliance with muffler device

Technical Field

The invention relates to a household appliance, in particular a floor treatment appliance, having an appliance housing, a fan arranged in the appliance housing, an outlet opening formed in the appliance housing downstream of the fan in the direction of flow, a flow channel connecting the outlet opening to the fan in a fluid-conducting manner, and a sound damping device assigned to the flow channel for damping sound generated by the operation of the household appliance.

Prior Art

Household appliances of the aforementioned type are known in the prior art. These are, for example, floor treatment devices, in particular suction cleaning devices, which have a fan for sucking dust and dirt from the surface to be cleaned. The suction is usually transferred into the suction chamber by means of a fan and collected there, while the air purified by the filter flows to the fan and finally to the discharge.

Sound waves are generated by the operation of the fan and the associated rotation of the fan blades, which sound waves are inevitably audible to the user during operation of the household appliance. In order to reduce the noise background associated therewith to such an extent that the user does not perceive the noise background as a disturbance, mufflers are known from the prior art which are inserted into the device housing of the household appliance.

Furthermore, it is known in the prior art, for example in the field of pipe mufflers for air lines, to provide the flow channel from the inside with a perforated carrier structure which carries an acoustic foam or a nonwoven. This results in an increase in the pressure loss, so that the suction can no longer be removed as well from the surface to be cleaned as in the case of suction cleaning devices without such a muffler. To balance the negative effects on noise reduction efficiency, the suction cleaning device must be equipped with an efficient fan and drive motor.

Disclosure of Invention

Starting from the prior art described above, the object of the invention is to provide a household appliance having a sound-damping device which has the greatest possible structural volume and at the same time enables a desired noise reduction.

In order to solve the above-mentioned problem, it is proposed that the sound damping device has a plurality of sound-absorbing wall elements which together form at least one section of the flow channel, wherein the wall elements have wall surfaces which are curved relative to the longitudinal extent of the flow channel and are positioned relative to one another such that the flow path formed between the mutually opposite wall surfaces extends in a curved manner.

According to the invention, the flow channel is at least curved relative to the section extending in the longitudinal direction thereof, so that the air flow guided in the flow channel impinges upon the sound-absorbing wall element several times in the flow direction and can be at least partially absorbed there. The flow channel is thereby provided on the one hand with a wall element from the inside which absorbs sound and on the other hand leads to an increased total absorption due to multiple reflections of the air flow on the wall element. The essential idea of the invention is to design the flow channel as curved as possible, rather than straight or angular. Contrary to, for example, abrupt (discontinuous) changes in direction of the flow channel, the pressure loss is kept as small as possible. Thus, the change in direction occurs along a curved flow path in accordance with the present invention. In particular, it is preferred that the free-flow cross section between the mutually opposite wall surfaces of the flow channel has a defined minimum dimension, which is determined as a function of the volume flow of the air flow guided in the flow channel. The free-flow cross section should optimally have at least one value which is equal to 0.96 times the square value of the volume flow, i.e. 0.96 × Q2, where Q is the value of the volume flow. With regard to the sound-absorbing properties of the wall elements, the wall elements should ideally absorb 100% of the sound energy. Since this is practically impossible, the sound damping device as a whole should achieve a sound absorption of at least 50% relative to the sound component to be attenuated.

It is also proposed that the flow path is configured in an S-shape, so that the flow path generates at least two direction reversals in the flow channel. The flow path thus has at least two substantially opposite changes of direction for the air flow guided within the flow channel, wherein the shape of the flow path is referred to herein as S-shape. It is however self-evident that other curved shapes with at least two opposite changes of direction, in particular substantially 180 deg., are also within the scope of the invention, such as a zigzag shape of the flow channel. A directional change of 145 ° to 180 ° may also optimally achieve the effect according to the invention. The directional diversion of the flow path can in principle be located at any point of the flow channel and be interrupted by a straight flow channel section. Furthermore, not only the sound-absorbing wall elements can participate in the S-shaped formation of the flow path, but also the wall regions that substantially reflect sound. Furthermore, the linearly configured wall regions of the flow channel can also be configured to absorb sound. In a mixed configuration of predominantly sound-absorbing and predominantly sound-reflecting and straight-line and curved wall regions, it is important that the flow channel has at least one section which contains the curved and sound-absorbing wall element and thus forces a curved course guidance for the flow path, while at least sectionally having the absorption properties of the curved wall element.

It is furthermore proposed that the flow channel has a constant flow cross section along the flow path between the mutually opposite wall elements. According to this embodiment, the distance between the wall elements lying opposite one another is kept constant, wherein the curved wall surfaces of the wall elements run parallel to one another following the curvature. It is thereby achieved that the flow cross section remains constant along the flow path, preferably starting from the fan up to the outlet opening of the flow duct. As previously mentioned, the flow cross-section is desirably greater than the minimum flow cross-section, which is at least 0.96x volumetric flow rate in size ² 。

According to a particular embodiment, it is proposed that the sound damping device has a carrier body for receiving a sound-absorbing wall element. According to this embodiment, the sound-damping device is preferably of modular design, i.e. it is formed by a carrier body and a plurality of sound-absorbing wall elements which can be connected to the carrier body. These sound-absorbing wall elements can particularly preferably be detachably connected to the carrier body, so that they can also be replaced afterwards. In the production of the household appliance, the sound-damping device is first assembled from a carrier body and a plurality of sound-absorbing wall elements before the sound-damping device is installed in the household appliance. This embodiment also makes it possible to assemble the carrier body and the wall element individually, depending on the type of the respective household appliance, so that an individual sound damping device can be produced for various household appliances. For example, the sound-absorbing wall element may be adapted to various noise spectra of the household appliance. The carrier body particularly preferably provides slots which are universally suitable for different sound-absorbing wall elements. The wall elements differ, for example, in material composition and/or material thickness. The carrier body is made of a hard plastic, for example ABS (acrylonitrile butadiene styrene) or PP (polypropylene). The carrier body first of all forms a complete sound damping device in combination with the sound-absorbing wall element received by the carrier body. In interaction, the flow path of the flow channel is thus formed on the one hand by the surface of the sound-absorbing wall element and on the other hand also by the surface of the carrier body. In domestic appliances, the carrier is arranged between the air outlet of the fan or the motor-fan unit and the outlet of the appliance housing. Furthermore, the outer surface of the carrier body preferably rests against the device housing of the household appliance from the inside. The carrier can be fixed to the device housing, for example by a screw connection, a snap connection, a plug connection or the like. The sound-absorbing wall element is inserted in a gas-tight manner into the carrier body, so that the air flow guided inside the carrier body cannot leave the flow path through possible openings or gaps between the material of the carrier body and the material of the wall element.

It may also be provided that the carrier body has a carrier body wall at least in a partial region of the carrier body, wherein the carrier body wall and the wall element inserted into the carrier body form an outwardly gas-tight flow duct section which is connected on the one hand to the fan in a gas-tight manner and on the other hand to the outlet opening of the device housing in a gas-tight manner. According to this embodiment, the air flow or the sound waves guided in the air flow are effectively prevented from shorting around the carrier or at least a partial region of the carrier. According to a particular embodiment of the invention, the carrier wall of the carrier can be arranged relative to the outlet opening of the fan in such a way that the air flow leaving the fan is divided into two partial flows which flow separately from one another inside the carrier to the outlet opening of the device housing. In this case, two partial flow channels can be produced inside the carrier body, which extend in each case in an S-shape and then communicate with a common air outlet of the carrier body. The carrier wall can in particular be orthogonal to the outflow direction of the air flow leaving the fan, so that a first directional diversion of the air flow guided in the flow path is already achieved when flowing into the carrier. Thus, as the air flow enters the carrier, a 90 ° diversion and a division of the air flow entering the carrier into two parts can basically already be achieved, for example. The two partial air flows then flow in the flow direction behind the carrier wall with a 180 ° deflection toward one another and can be deflected again by the curved wall element by 90 °, so that the partial air flows then flow parallel to one another, preferably, however, further apart from one another toward the outlet opening of the device housing.

The wall element of the sound damping device is preferably made of open-cell foam. The wall element may in particular be made of melamine resin foam or polyurethane foam. In practice, these materials have proved to be particularly effective in order to absorb the sound frequencies that are common in household appliances, in particular the sound frequencies caused by fans.

Furthermore, it is preferred that the wall element has a wall thickness which corresponds to at least one quarter of the wavelength of the sound component to be attenuated. The wall thickness of the wall element determines from which Cut-off Frequency the sound component is absorbed, the so-called "Cut-on Frequency". The acoustic frequency of the resonance mode of the sound (Schnallschnelle) has an amplitude of 0 at the area of the reflecting section of the wall element. From this, the acoustic frequency then extends in the direction of the opposing wall element with a sinusoidal oscillation having a wavelength λ. In order for the sound-absorbing material of the wall element to exert its effect, the wall thickness of the wall element must be equal to at least one quarter of the wavelength of the relevant sound component. Thereby, the closest peak of the amplitude of the acoustic frequency may still be located within the absorbing material of the wall element, thereby effectively reducing the acoustic energy.

It is furthermore proposed that the wall element has a hermetically closed wall on the outer side of the wall element which is directed outward and away from the guided air flow. This prevents the material of the remaining openings of the wall element from being completely penetrated by the air flow, but rather retains the guided air in the flow channel. The respective wall element therefore has an insulating layer which prevents air and also sound from escaping from the flow channel.

Finally, it is proposed that the flow channel has a noise reduction wall, wherein a wall plane of the noise reduction wall is oriented parallel to the flow path, and wherein the noise reduction wall is arranged centrally between mutually opposite wall faces of the flow channel with reference to a direction orthogonal to a longitudinal extension of the flow channel. The noise reduction walls are likewise designed to reduce the acoustic energy of the resonant sound component in the relevant flow channel section containing the noise reduction walls. The noise reduction wall is arranged centrally between mutually opposite wall surfaces of the flow channel in the flow channel, so that the plane of the noise reduction wall is located exactly where the frequency amplitude of the acoustic frequency has a maximum. Thus, the noise reduction wall is spaced from the inner wall of the flow channel and is substantially centrally located within the open cross-section of the flow channel. Thus, the sound absorbing noise reduction wall is located exactly where a particularly large amount of sound energy is directed in the air flow. Furthermore, since the noise reduction wall extends parallel to the main flow direction of the air flow in the flow channel, the air flow is not significantly impeded, so that the suction force of the fan or the household appliance remains as high as possible. In other words, the noise reduction wall is arranged in the flow channel in such a way that the air flow delivered by the fan can flow in the flow channel to the discharge opening with as little pressure loss as possible, while on the other hand the sound generated by the fan is optimally attenuated. The noise reduction walls are oriented parallel to the direction of the air flow, while the sound waves move between the mutually opposite inner walls of the flow channel, that is to say the sound waves are transverse to the noise reduction walls. Thereby, the air flow generated by the fan can flow through the flow channel and through the material of the noise reduction wall as far as possible without pressure loss. At the same time, optimum sound absorption is achieved by the noise-reducing wall arranged in the acoustic frequency maximum. The partial air streams flowing separately before reaching the noise reduction wall can, if necessary, be mixed again through the noise reduction wall, so that the air streams can flow through the flow channels as largely as possible without pressure losses. This increases the efficiency of the silencing device, i.e. the ratio of noise reduction to pressure loss.

Drawings

The present invention is illustrated in detail below with reference to examples. In the drawings:

figure 1 shows a household appliance according to the invention,

figure 2 shows a principle view of a flow channel with a curved wall element,

fig. 3 shows a longitudinal section of a flow channel with a sound damping device, which has a carrier body and a wall element inserted therein,

FIG. 4 shows a cross-sectional view of the flow channel according to FIG. 3

Figure 5 shows a wall element according to a first embodiment,

figure 6 shows a wall element according to another embodiment,

figure 7 shows a wall element according to another embodiment,

figure 8 shows a wall element according to another embodiment,

fig. 9 shows a carrier for holding a wall element.

Detailed Description

Fig. 1 shows an exemplary possible embodiment of a household appliance 1 according to the invention, which is designed here as a floor treatment appliance. Here, the home appliance 1 is a vacuum cleaner manually operated by a user. The household appliance 1 has a base device 18 and an accessory device 19 which is releasably connected to the base device 18. The accessory device 19 is here, for example, a suction nozzle with a suction opening 20 and a floor treatment element 21 assigned to the suction opening 20. The base device 18 of the household appliance 1 has an appliance housing 2, in which there are also a suction chamber 17 and a fan 3. The flow passage 5 connects the exhaust side of the fan 3 and the discharge port 4. The fan 3 serves to suck in suction into the suction chamber 17, wherein suction located on the surface to be cleaned can be sucked into the suction chamber 17 of the base device 18 through the suction opening 20 of the accessory device 19. The suction remains in the suction chamber 17 while the cleaned air flows through the fan 3 and the flow channel 5 to the discharge opening 4 of the household appliance 1.

The base device 18 of the household appliance 1 also has a handle 23 with a handle 22. Arranged on the handle 22 is a switch 24, by means of which a user can set certain operating modes of the household appliance 1, for example the intensity level of the fan 3 and/or the rotational speed of the floor-treating element 21 of the accessory device 19.

By operation of the fan 3, sound is generated which is conveyed via the flow channel 5 to the outlet opening 4 and into the surroundings of the household appliance 1. In order to configure the household appliance 1 in such a way that the application of the household appliance is comfortable for the user, the household appliance 1 has a sound-damping device 6 (see in particular fig. 3) which is shown in detail with reference to the further figures. The frequency of the sound emitted by the fan 3 depends on different parameters, such as the rotational speed of the motor shaft of the fan 3. Of particular interest are the so-called blade pass frequencies of the fan 3, which are determined on the one hand by the rotational speed of the motor shaft and on the other hand by the number of fan blades of the fan 3. The sound-damping device 6 is therefore designed in particular such that the characteristic typical sound frequencies generated by the fan 3 of the household appliance 1 in a certain power level of the fan 3 are absorbed.

The principle on which the invention is based is explained in more detail here with reference to fig. 2. An important aspect of the invention is the geometric design of the flow channel 5 and the sound damping device 6, so that the sound components propagating in the flow channel 5 can be optimally absorbed. The flow duct 5 is thereby designed by means of the

curved wall elements

7, 8,9 of the sound damping device 6 in such a way that the flow path 11 formed between the

wall elements

7, 8,9 extends in a curved manner and that the sound components strike the wall surface 10 of the

wall elements

7, 8,9 as frequently as possible when passing through the flow path 11 and the energy of these sound components is further reduced with each reflection at the

wall elements

7, 8, 9. The share of the sound energy absorbed by the material of the

wall elements

7, 8,9 continues to increase (in absolute value) with increasing number of reflections.

The

wall elements

7, 8,9 are foam elements made of open-cell acoustically effective foam, for example melamine resin foam or polyurethane foam. On the side facing away from the flow path 11, the

wall elements

7, 8,9 have an outer side 14 (not shown in fig. 2) made of a sound-insulating material, so that sound waves entering the bores of the

wall elements

7, 8,9 cannot leave the

wall elements

7, 8,9 on the rear side, i.e. via the outer side 14, but rather the unabsorbed part of the sound waves is reflected into the flow path 11 in order to subsequently enter the mutually

opposite wall elements

7, 8,9 again. The

wall elements

7, 8,9 have a defined wall thickness d. This wall thickness d determines the depth of the absorption material of the

respective wall element

7, 8,9 from the flow path 11 in the direction of the sound-damping, i.e. reflecting, outer side 14 of the

wall element

7, 8, 9. The wall thickness d of the

wall elements

7, 8,9 is different for different angles of incidence of sound. The

wall elements

7, 8,9 or the absorbing material of the

wall elements

7, 8,9 can thus optimally absorb sound waves of a defined frequency, it being necessary here for the wall thickness d to be at least as great as one quarter of the wavelength of the sound component concerned. Hereby is achieved that the first maxima of the acoustic frequencies of the relevant sound components, which are closest to the

wall elements

7, 8,9, are within the absorption material of the

wall elements

7, 8, 9. The sound frequency of the sound waves between the

wall elements

7, 8,9 lying opposite one another has an amplitude of 0 at the reflected inner wall of the outer side 14 of the

wall element

7, 8,9 and is transmitted as a sinusoidal wave present to the

opposite wall element

7, 8,9, i.e. likewise up to the inner wall of the outer side 14 of this

wall element

7, 8,9, which reflects sound. It is important that the peak amplitude closest to the outer side 14 is also located within the absorbing material of the

wall elements

7, 8,9, whereby as much acoustic energy as possible is absorbed within the pores of the material and not returned into the flow path 11.

It is furthermore proposed that a minimum flow cross section be determined for the free flow cross section of the flow path 11 between the

wall elements

7, 8, 9. In practice, the minimum flow cross-section should be at least equal to 0.96x the volume flow rate, relative to the square value of the volume flow rate ² . This minimum flow cross section is preferably constant along the flow path 11, i.e. as far as possible from the fan 3 up to the outlet opening 4 of the device housing 2. Thereby, the pressure loss in the flow channel 5 can be kept small and the ratio between noise reduction and pressure loss, which represents the efficiency, is improved by more than 2.

These

wall elements

7, 8,9 are held in the device housing 2 of the household appliance 1 by means of the carrier body 12. The carrier 12 is shown in figure 9. The

individual wall elements

7, 8,9 are shown in fig. 5 to 7. These

wall elements

7, 8,9 and the noise damping wall 15, which is also shown in fig. 8, are pushed or inserted into corresponding receptacles of the carrier body 12, i.e. such that no gaps or gaps are created between the material of the carrier body 12 and the

wall elements

7, 8,9 through which air from the sound damping device 6 can escape. The carrier 12 is made of a rigid plastic, such as ABS or PP plastic.

As is also shown in fig. 3, the carrier body 12 is arranged in the flow channel 5 on the outlet side of the fan 3, i.e. between the fan 3 and the outlet opening 4. The outer side of the carrier 12 in this case touches the inner side of the device housing 2, for example, and is fixed to the device housing 2, for example, in particular by a screw connection, a plug connection, a snap connection, or the like. The carrier body 12, together with the

wall elements

7, 8,9 and a noise damping wall 15, which will be explained in more detail below, forms a mounting module which can be mounted in its entirety in the device housing 2 of the household appliance 1. The carrier body 12 comprises not only its own walls, for example the carrier body wall 13 serving as a flow guiding contour, but also retaining elements for the

wall elements

7, 8,9 inserted into the carrier body 12 and the noise damping wall 15. Since the wall surfaces 10 of the

wall elements

7, 8,9 also have a flow-guiding function, the carrier body 12, which completely has all the

wall elements

7, 8,9 and the noise-reducing wall 15, completely forms the flow path 11 of the relevant section of the flow duct 5.

As shown in fig. 3, proceeding from the air outlet of the fan 3, the outlet air of the fan 3 is divided into two separate flow paths 11 which flow around the carrier wall 13 in opposite directions on mutually opposite edges of the carrier wall 13, i.e. in the downward and upward direction in the image plane shown in fig. 3. In this case, the two flow paths 11 each undergo a 180 ° deflection, which is caused by the deflection of the blow-out stream around the edge of the carrier wall 13. Subsequently, the flow path 11 flows through between the

wall elements

7, 8,9, i.e. a first flow path 11 between the wall element 8 and the wall element 7 and a second flow path between the wall element 9 and the wall element 7. The wall element 7 is inserted substantially centrally into the carrier wall 13 and has, with reference to the longitudinal section of fig. 3, a substantially isosceles triangular shape with concave sides. The wall element 7 is shown in detail in fig. 5. The wall element 7 continues the curvature of the carrier wall 13 by its concave wall surface 10 and forms with the opposite wall element 8 or wall element 9 a flow path 11 which extends substantially with a constant open cross-sectional area. The tip of the wall element 7 connects seamlessly in this case a noise reduction wall 15, which is likewise inserted into the carrier body 12 and is shown in more detail in fig. 8.

The flow paths 11 continue after passing through the wall elements 7 between the wall elements 8 and the noise reduction wall 15 and between the wall elements 9 and the noise reduction wall 15, wherein the flow paths 11 then first run parallel to the wall plane 16 of the noise reduction wall 15 and then continue to flow around the respective

curved wall elements

8,9, so that flow diversion is achieved again. Overall, the flow path 11 thus forms substantially an S-shape or a Z-shape in the sound damping device 6. By means of the curved course of the respective flow path 11, a maximum amount of interaction between the guided air flow and the absorption material of the

wall elements

7, 8,9 is produced. The noise reduction wall 15 also has sound-absorbing material, i.e. preferably a fiber-reinforced nonwoven which is reinforced here, for example, (on a volume basis) by glass fibers or carbon fibers for about 30%. The wall thickness of the noise reduction wall 15 is for example less than 4mm. The noise reduction wall 15 may be configured to be air-permeable, so that a portion of the air may intrude into each other as necessary from the flow path 11 extending parallel to the wall plane 16 of the noise reduction wall 15. The pressure loss in the flow channel 15 is thereby made as small as possible and, consequently, the overall efficiency (noise reduction versus pressure loss) of the sound-damping device 6 is as high as possible. The flow paths 11 have a width between the wall plane 16 of the noise-reducing wall 15 and the wall element 8 and between the noise-reducing wall 15 and the wall element 9, respectively, which width corresponds approximately to a quarter wavelength of the sound component to be attenuated. Thereby the centre plane of the noise reduction wall 15 is located in the peak of the acoustic frequency of the resonance mode (of the dominant acoustic component).

Fig. 4 shows a cross section of a flow channel 5 with a sound damping device 6. Here, the viewing direction is parallel to the direction in which the wall plane 16 of the noise reduction wall 15 faces the fan 3. It can be seen that the flow paths 11 extending in parallel on both sides of the noise reduction wall 15 are oriented, said flow paths extending in the direction of the central wall element 7. As can be seen in particular from fig. 3 and from the shape design of the

wall elements

7, 8,9 of fig. 5 to 7, it is important that the flow paths 11 are designed as curved as possible without bevels. This ensures that the pressure losses caused in the flow channel 5 are kept as small as possible. Additionally, the noise damping effect is increased by implementing the curvature and material of the absorbing

wall elements

7, 8,9 and the material of the absorbing noise damping wall 15, so that the efficiency of the sound damping device 6 is as high as possible.

List of reference numerals

1. Household appliance

2. Equipment casing

3. Fan (Ref. TM. Fan)

4. Discharge outlet

5. Flow channel

6. Noise-abatement equipment

7. Wall element

8. Wall element

9. Wall element

10. Wall surface

11. Flow path

12. Carrier body

13. Carrier wall

14. Outside side

15. Noise reduction wall

16. Wall plane

17. Aspirant chamber

18. Basic equipment

19. Accessory device

20. Suction mouth

21. Floor treatment element

22. Handle (CN)

23. Handle rod

24. Switch with a switch body

d wall thickness

Claims

1. A household appliance (1) having an appliance housing (2), a fan (3) arranged in the appliance housing (2), an outlet opening (4) formed in the appliance housing (2) downstream of the fan (3) in the flow direction, a flow channel (5) which connects the outlet opening (4) to the fan (3) in a flow-conducting manner, and a sound damping device (6) which is assigned to the flow channel (5) and serves to damp sound generated by operation of the household appliance (1), wherein the sound damping device (6) has a plurality of sound-absorbing wall elements (7, 8, 9) which together form at least a section of the flow channel (5), wherein the wall elements (7, 8, 9) have wall surfaces (10) which are curved in relation to the longitudinal extension of the flow channel (5) and are positioned relative to one another such that a flow path (11) formed between the mutually opposite wall surfaces (10) extends in a curved manner, characterized in that the sound damping device (6) has a wall element (7, 8, 9) for receiving sound-absorbing sound, and in that the noise damping wall (11) has a noise-reducing wall (15) which is oriented parallel to the flow channel (5), and in which the noise-reducing wall (15) is oriented parallel to the flow channel (5), the noise reduction wall (6) is arranged centrally between mutually opposite wall surfaces (10) of the flow duct (5) with reference to a direction orthogonal to the longitudinal extent of the flow duct (5), and wherein the carrier body (12) together with the wall elements (7, 8, 9) and the noise reduction wall (15) forms a mounting module which can be mounted in its entirety in the device housing (2), i.e. between the fan (3) and the outlet opening (4) of the device housing (2).

2. A household appliance (1) according to claim 1, characterized in that the flow path (11) is configured S-shaped such that the flow path (11) creates at least two direction reversals within the flow channel (5).

3. A household appliance (1) according to claim 1, characterized in that the flow channel (5) has a constant flow cross-section along the flow path (11) between the mutually opposite wall elements (7, 8, 9).

4. A household appliance (1) as in claim 1, characterized in that the carrier body (12) has a carrier body wall (13) at least in a partial region of the carrier body (12), wherein the carrier body wall (13) and the wall elements (7, 8, 9) inserted into the carrier body (12) form an outwardly gas-tight closed flow duct section which is connected on the one hand gas-tight to the fan (3) and on the other hand gas-tight to the outlet opening (4) of the appliance housing (2).

5. A household appliance (1) as in claim 1, characterized by the wall elements (7, 8, 9) that are composed of open-cell foam.

6. A household appliance (1) as in claim 1, characterized by the wall elements (7, 8, 9) that are made of melamine resin foam or polyurethane foam.

7. A household appliance (1) as in claim 1, characterized by the wall element (7, 8, 9) that has a wall thickness (d) that corresponds to at least a quarter of the wavelength of the sound component to be attenuated.

8. A household appliance (1) as in claim 1, characterized by the wall element (7, 8, 9) that has a hermetically closed wall on its outer side (14) that is directed outwards and away from the directed air flow.

9. Household appliance (1) according to claim 1, wherein the household appliance (1) is a floor treatment appliance.