HOUSEHOLD APPLIANCE WITH A SOUND REDUCTION DEVICE

Description

field of technology

[0001] The invention relates to a household appliance, in particular a soil tillage appliance, comprising an appliance housing, a fan arranged in the appliance housing, an outlet opening formed in the appliance housing behind the fan in the flow direction, a flow channel which connects the outlet opening to the fan in a flow-guiding manner, and a sound damping device assigned to the flow channel for damping sound generated by operation of the household appliance, wherein the sound damping device comprises a plurality of sound-absorbing wall elements which together form at least a portion of the flow channel, wherein the wall elements have a wall surface which is curved with respect to a direction of a longitudinal extension of the flow channel and are positioned relative to one another such that a flow path formed between opposing wall surfaces is curved,wherein the sound-damping device has a support body for receiving the sound-absorbing wall elements. State of the art

[0002] Household appliances of the aforementioned type are known in the prior art. These include, for example, floor-treating devices, in particular vacuum cleaners, with a fan for vacuuming dust and dirt from a surface to be cleaned. The vacuumed material is usually transferred by the fan into a vacuum chamber and collected there, while air purified by a filter flows to the fan and finally to the outlet.

[0003] Household appliances with sound-damping devices are known, for example, from EP 0 099 466 A1, US 5 159 738 A, US 2004 / 200664 A1, EP 3 207 846 A1, US 2009 / 269219 A1, CN 208 011 981 U, and CN 2 427 764 Y. In particular, it is also known to design at least one section of a flow channel of the household appliance such that its walls are curved relative to a direction of a longitudinal extension of the flow channel in order to further increase the degree of sound absorption. It is also known from US 2009 / 0269219 A1 to arrange an additional sound-damping element centrally within a flow channel of a silencer in order to achieve an additional sound-damping effect.

[0004] The operation of the fan and the associated rotation of the fan blades generate sound waves that inevitably become audible to the user during operation of the household appliance. To reduce the associated noise to such an extent that the user does not find it disturbing, silencers are known in the art. These are incorporated into the appliance housing.

[0005] Furthermore, it is known in the prior art, for example in the field of pipe silencers for air ducts, to equip flow channels on the inside with a perforated support structure that supports acoustic foam or fleece. This results in increased pressure loss, so that, with a vacuum cleaning device, vacuumed material cannot be removed from the surface to be cleaned as effectively as would be the case without such a silencer, for example. To compensate for the negative effect on the silencer's efficiency, the vacuum cleaning device would have to be equipped with a more powerful blower or drive motor. Summary of the invention

[0006] Based on the aforementioned prior art, it is the object of the invention to design a household appliance with a sound-damping device which has the smallest possible construction volume while at the same time providing optimal sound damping.

[0007] To achieve this object, it is proposed that the flow channel has a sound reduction wall, wherein a wall plane of the sound reduction wall is oriented parallel to the flow path and wherein the sound reduction wall is arranged centrally between the opposite wall surfaces of the flow channel with respect to a direction orthogonal to the longitudinal extent of the flow channel, and wherein the carrier body together with the wall elements and the sound reduction wall forms an installation module which can be installed as a whole in the device housing, namely between the fan and the outlet opening of the device housing.

[0008] The sound damping device comprises a plurality of sound-absorbing wall elements which together form at least a portion of the flow channel, wherein the wall elements have a wall surface which is curved relative to a direction of a longitudinal extension of the flow channel and are positioned relative to one another in such a way that a flow path formed between opposite wall surfaces is curved.

[0009] The flow channel is curved, at least over a section along its longitudinal extent, so that the air flow guided in the flow channel encounters the sound-absorbing wall elements several times in the direction of flow and can be at least partially absorbed there. This means that, on the one hand, the flow channel is provided with sound-absorbing wall elements on the inside, and, on the other hand, the repeated reflections of the air flow by the wall elements result in an increased overall absorption coefficient. The essential idea of ​​the invention is to design the flow channel as curved as possible and not in a straight or angular manner. In contrast to, for example, abrupt (discontinuous) changes in direction of the flow channel, the pressure losses are kept as low as possible. According to the invention, a change in direction thus occurs along a curved flow path.Particularly preferably, a free flow cross-section between the opposing wall surfaces of the flow duct has a certain minimum size, which is dimensioned depending on the volume flow of the air flow guided in the flow duct. The free flow cross-section should ideally have an amount that corresponds to at least 0.96 times the amount of the volume flow 2<, i.e. 0.96 x Q 2< , where Q is the amount of the volume flow. In terms of the sound-absorbing properties of the wall elements, they should ideally absorb 100 percent of the sound energy. Since this is rarely possible in practice, the sound dampening device should achieve a total sound absorption of at least 50 percent based on the proportion of sound to be dampened.

[0010] Furthermore, it is proposed that the flow path be S-shaped, so that the direction of the flow path changes at least twice within the flow channel. The flow path thus has at least two essentially opposite changes of direction for the air flow guided within the flow channel, whereby the shape of the flow path is referred to here as S-shaped. However, it goes without saying that other curvature shapes which have at least two opposite changes of direction, in particular essentially 180° changes, are also within the scope of the invention, for example a Z-shape of the flow channel. Changes in direction from 145° to 180° can also optimally achieve the effect according to the invention. The directional deflections of the flow path can in principle be located at any point in the flow channel and can be interrupted by straight flow channel sections.Furthermore, it is possible that not only the sound-absorbing wall elements contribute to the S-shape of the flow path, but also wall sections that are designed to be essentially sound-reflecting. Furthermore, straight wall sections of the flow channel can also be designed to be sound-absorbing. In a mixed design consisting of predominantly sound-absorbing and predominantly sound-reflecting wall sections, as well as straight and curved wall sections, it is essential that the flow channel has at least one section that contains curved and sound-absorbing wall elements, thus forcing a curved route for the flow path, while at the same time the curved wall elements have absorption properties at least in some sections.

[0011] Furthermore, it is proposed that the flow channel between the opposing wall elements has a constant flow cross-section along the flow path. According to this embodiment, the distance between the opposing wall elements remains constant, with the curved wall surfaces of the wall elements running parallel to one another following the curvature. This ensures that the flow cross-section also remains constant along the flow path, preferably from the fan to the outlet opening of the flow channel. As previously explained, the flow cross-section is ideally larger than a minimum flow cross-section, which is dimensioned as at least 0.96 x volume flow 2< .

[0012] According to the invention, the sound-damping device comprises a support body for accommodating the sound-absorbing wall elements. According to this embodiment, the sound-damping device is preferably of modular design, namely comprising a support body and a plurality of sound-absorbing wall elements that can be connected to the support body. Particularly preferably, the sound-absorbing wall elements can be detachably connected to the support body, thus allowing subsequent replacement. During manufacture of the household appliance, the sound-damping device can initially be assembled from the support body and the sound-absorbing wall elements before installation of the sound-damping device in the household appliance.This design also allows for individual fitting of the support body with wall elements, depending on the type of household appliance, so that a customized soundproofing device can be produced for each household appliance. For example, the sound-absorbing wall elements can be adapted to the respective sound emission spectrum of the household appliance. The support body particularly preferably provides slots that are universally suitable for different wall elements. For example, the wall elements can differ in terms of material composition and / or wall thickness of the sound-absorbing material. The support body itself is made, for example, of a hard plastic such as ABS (acrylonitrile butadiene styrene) or PP (polypropylene). The support body only forms a complete soundproofing device in conjunction with the installed sound-absorbing wall elements.In interaction, the flow paths of the flow channel are thus formed, on the one hand, by the surfaces of the sound-absorbing wall elements and, on the other hand, by the surfaces of the support body. Within the household appliance, the support body is arranged between an exhaust opening of the fan or a motor-fan unit and the outlet opening of the appliance housing. Furthermore, an outer surface of the support body preferably rests against the appliance housing of the household appliance from the inside. The support body can be fixed to the appliance housing, for example, by a screw connection, clamp connection, plug connection, or similar fixing method. The sound-absorbing wall elements are inserted into the support body in an airtight manner, so that the air flow guided within the support body cannot leave the flow path through any openings or cracks between the material of the support body and the material of the wall elements.

[0013] In addition, it can be provided that the carrier body has a carrier body wall at least in a partial area of ​​the carrier body, wherein the carrier body wall and the wall elements inserted into the carrier body form a flow channel section that is hermetically sealed to the outside and is connected in an airtight manner on the one hand to the fan and on the other hand to the outlet opening of the device housing. According to this embodiment, the air flow or sound carried in the air flow is effectively prevented from short-circuiting around the carrier body or at least partial areas of the carrier body. According to a special embodiment of the invention, the carrier body wall of the carrier body can be positioned relative to an outlet opening of the fan in such a way that the air flow leaving the fan is divided into two flow components that flow separately from one another within the carrier body to the outlet opening of the device housing.In this respect, two partial flow channels can be created within the support body, each of which runs in an S-shape and subsequently opens into a common air outlet of the support body. In particular, the support body wall can be positioned orthogonally to an outflow direction of the air flow leaving the fan, so that an initial directional deflection of the guided air flow in the flow path is achieved as soon as it enters the support body. Thus, with the entry of the air flow into the support body, a 90° deflection and bifurcation of the air flow entering the support body can essentially be achieved.The two partial air flows then run towards each other in the flow direction behind the carrier body wall in a 180° deflection and can be deflected again by 90° by a wall element which is curved, so that the partial air flows then flow parallel to each other, but preferably further separated from each other, towards the outlet opening of the device housing.

[0014] The wall elements of the sound-damping device are preferably made of an open-pore foam. In particular, the wall elements can be made of melamine resin foam or polyurethane foam. These materials have proven particularly effective in absorbing common sound frequencies in household appliances, especially sound frequencies generated by a fan.

[0015] Furthermore, the wall elements preferably have a wall thickness that corresponds to at least a quarter of the wavelength of the sound component to be attenuated. The wall thickness of the wall element determines the cut-on frequency at which sound components are absorbed. The sound velocity of a resonance mode of the sound has an amplitude of 0 at a reflecting portion of the wall element. From there, the sound velocity then propagates towards the opposite wall element in a sine wave with a wavelength of λ. In order for the sound-absorbing material of the wall element to be effective, the wall thickness of the wall element must correspond to at least a quarter of the wavelength λ of the respective sound component. This allows the nearest peak of the amplitude of the sound velocity to still be within the absorbing material of the wall element, effectively reducing the sound energy.

[0016] Furthermore, it is proposed that the wall elements have an airtight wall on their outward-facing outer side, away from the guided air flow. This ensures that the otherwise open-pore material of the wall elements cannot be completely permeated by the air flow, but rather that the guided air remains within the flow channel. Thus, the respective wall element has an insulating layer that prevents air and sound from escaping from the flow channel.

[0017] According to the invention, the flow channel has a sound reduction wall, wherein a wall plane of the sound reduction wall is oriented parallel to the flow path and wherein the sound reduction wall is arranged centrally between the opposing wall surfaces of the flow channel with respect to a direction orthogonal to the longitudinal extent of the flow channel. The sound reduction wall is also designed to reduce the sound energy of the resonant sound components in the respective flow channel section containing the sound reduction wall. The sound reduction wall is arranged centrally between the opposing wall surfaces of the flow channel in the flow channel, so that the plane of the sound reduction wall lies precisely where the velocity amplitude of the sound velocity has a maximum.The sound reduction wall is thus spaced from the inner wall of the flow duct and is located essentially centrally within the opening cross-section of the flow duct. This places the sound-absorbing sound reduction wall precisely where the airflow carries the greatest amount of sound energy. Furthermore, since the sound reduction wall runs parallel to the main airflow direction in the flow duct, the airflow is not significantly impeded, so that the suction power of the fan or household appliance remains as high as possible. In other words, the sound reduction wall is positioned within the flow duct in such a way that the airflow conveyed by the fan can flow to the outlet opening with the lowest possible pressure loss within the flow duct, while at the same time optimally reducing the sound generated by the fan.The sound reduction wall is oriented parallel to the direction of the air flow, while the sound waves form between the opposing inner walls of the flow duct, i.e., perpendicular to it. This allows the air flow generated by the fan to flow through the flow duct with as little pressure loss as possible and penetrate the material of the sound reduction wall. At the same time, optimal acoustic absorption takes place thanks to the sound reduction wall positioned at the maximum sound velocity. The partial air flows flowing separately before reaching the sound reduction wall can, if necessary, mix again through the sound reduction wall, allowing the air flow as a whole to flow through the flow duct with as little pressure loss as possible. This increases the efficiency of the sound dampening device, i.e., the ratio of sound reduction to pressure loss. Short description of the drawings

[0018] The invention is explained in more detail below using exemplary embodiments. They show: Fig. 1 shows a household appliance according to the invention, Fig. 2 shows a schematic diagram of a flow channel with curved wall elements, Fig. 3 shows a longitudinal section of a flow channel with a sound damping device which has a carrier body and wall elements inserted therein, Fig. 4 shows a cross section of the flow channel according to Fig. 3 , Fig. 5 a wall element according to a first embodiment, Fig. 6 a wall element according to a further embodiment, Fig. 7 a wall element according to a further embodiment, Fig. 8 a wall element according to a further embodiment, Fig. 9 a support body for holding wall elements. Description of the embodiments

[0019] Figure 1shows, by way of example, a possible embodiment of a household appliance 1 according to the invention, which is designed here as a floor-treating appliance. Here, the household appliance 1 is a vacuum cleaner that is manually operated by a user. The household appliance 1 has a base unit 18 and an attachment 19 detachably connected to the base unit 18. The attachment 19 is, for example, a suction nozzle with a suction mouth 20 and a floor-treating element 21 associated with the suction mouth 20. The base unit 18 of the household appliance 1 has a device housing 2, which contains, among other things, a suction material chamber 17 and a fan 3. A flow channel 5 connects an outlet side of the fan 3 to an outlet opening 4.The blower 3 serves to suck in the suction material into the suction material chamber 17, whereby the suction material located on a surface to be cleaned can be sucked through the suction mouth 20 of the attachment 19 into the suction material chamber 17 of the base unit 18. While the suction material remains within the suction material chamber 17, cleaned air flows through the blower 3 and the flow channel 5 to the outlet opening 4 of the household appliance 1.

[0020] The base unit 18 of the household appliance 1 further comprises a shaft 23 with a handle 22. A switch 24 is arranged on the handle 22, via which a user can set a specific operating mode of the household appliance 1, for example, an intensity level of the fan 3 and / or a speed of the soil cultivation element 21 of the attachment 19.

[0021] The operation of the fan 3 generates sound, which is carried via the flow channel 5 to the outlet opening 4 and into the surroundings of the household appliance 1. In order to design the household appliance 1 in such a way that its use is pleasant for a user, the household appliance 1 has a sound dampening device 6, which is shown in more detail with reference to the other figures (see in particular Figure 3). The sound frequencies emitted by the fan 3 depend on various parameters, for example, the speed of a motor shaft of the fan 3. Of particular interest is a so-called blade passing frequency of the fan 3, which is determined, on the one hand, by the speed of the motor shaft and, on the other hand, by the number of fan blades of the fan 3. The sound dampening device 6 is therefore designed, in particular, such that the characteristic sound frequencies of the fan 3 of the household appliance 1, which arise at certain power levels of the fan 3, are absorbed.

[0022] The principle underlying the invention will now be explained using the Figure 2explained in more detail. An essential aspect of the invention is the geometric design of the flow channel 5 or the sound damping device 6 in order to be able to absorb sound components propagating within the flow channel 5 as best as possible. Therefore, the flow channel 5 is designed by a plurality of curved wall elements 7, 8, 9 of the sound damping device 6 such that a flow path 11 formed between the wall elements 7, 8, 9 runs in a curved manner and the sound components strike a 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 the sound components is further reduced with each reflection at a wall element 7, 8, 9. The proportion of the sound energy absorbed by the material of the wall element 7, 8, 9 increases with the number of reflections (in absolute terms).

[0023] The wall elements 7, 8, 9 are foam elements made of an open-pore 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 a (in Figure 2not shown) outer side 14 made of a sound-insulating material, so that the sound waves entering the pores of the wall elements 7, 8, 9 cannot leave the wall elements 7, 8, 9 on the back, i.e. via the outer side 14, but rather the non-absorbed portions of the sound waves are reflected back into the flow path 11, in order to then enter an opposite wall element 7, 8, 9. The wall elements 7, 8, 9 have a certain wall thickness d. The wall thickness d determines the depth of the absorbing material of the respective wall element 7, 8, 9 from the flow path 11 in the direction of the sound-insulating, i.e. reflective outer side 14 of the wall element 7, 8, 9. The wall thickness d of the wall element 7, 8, 9 is different for different angles of entry of the sound. So that the wall element 7, 8, 9 orwhose absorbing material can optimally absorb a sound wave with a defined frequency, it is necessary that the wall thickness d is at least as large as a quarter of the wavelength of the relevant sound component. This ensures that a first maximum of the sound velocity of the relevant sound component, closest to the wall element 7, 8, 9, lies within the absorbing material of the wall element 7, 8, 9. The sound velocity of a sound wave standing between opposing wall elements 7, 8, 9 has an amplitude of 0 at the reflective inner wall of the outer side 14 of the wall element 7, 8, 9 and continues as a standing sine wave to the opposite wall element 7, 8, 9, namely also up to the inner wall of the sound-reflecting outer side 14 of the wall element 7, 8, 9.It is essential that the amplitude peak closest to the outer side 14 is still within the absorbing material of the wall element 7, 8, 9, so that as much sound energy as possible is absorbed within the pores of the material and does not return to the flow path 11.

[0024] Furthermore, it is recommended to specify a minimum flow cross-section 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 0.96 x volume flow 2<, based on the square of the volume flow. This minimum flow cross-section is preferably constant along the flow path 11, i.e., if possible, from the fan 3 to the outlet opening 4 in the device housing 2. This allows the pressure loss within the flow channel 5 to be kept low and an efficiency, which indicates the ratio between sound reduction and pressure loss, to be improved to over 2:1 or even beyond.

[0025] The wall elements 7, 8, 9 are held in the appliance housing 2 of the household appliance 1 by means of a support body 12. The support body 12 is in Figure 9 The individual wall elements 7, 8, 9 are Figures 5 to 7The wall elements 7, 8, 9 and a Figure 8 The further illustrated sound reduction wall 15 is inserted or plugged into corresponding receptacles of the support body 12, namely in such a way that no gaps or cracks are created between the material of the support body 12 and the wall elements 7, 8, 9, through which air can escape from the sound dampening device 6. The support body 12 is made of a rigid plastic such as ABS or PP.

[0026] As further stated in Figure 3As shown, the support body 12 is arranged in the flow channel 5 on the outlet side of the fan 3, namely between the fan 3 and the outlet opening 4. Here, the outer side of the support body 12 abuts, for example, the inside of the appliance housing 2 and is fixed to the appliance housing 2, for example, by a screw connection, plug connection, snap connection, or the like. The support body 12, together with the wall elements 7, 8, 9 and the sound reduction wall 15, which will be explained in detail later, forms an installation module that can be installed as a whole into the appliance housing 2 of the household appliance 1. The support body 12 comprises both its own walls, for example the support body wall 13, which acts as a flow-guiding contour, and holding elements for the wall elements 7, 8, 9 inserted into the support body 12, as well as the sound reduction wall 15.Since the wall surfaces 10 of the wall elements 7, 8, 9 also have flow-guiding functions, only the support body 12, which completely comprises all wall elements 7, 8, 9 as well as the sound reduction wall 15, completely forms the flow path 11 of the relevant section of the flow channel 5.

[0027] As in Figure 3 As shown, the exhaust air of the blower 3, coming from the outlet opening of the blower 3, is divided into two separate flow paths 11, which flow at opposite edges of the carrier body wall 13 in opposite directions around the carrier body wall 13, namely onto the image plane of the Figure 3in a downward direction and an upward direction. In this case, the two flow paths 11 each experience a directional deflection of 180°, which is caused by the deflection of the blow-out flow around the edges of the carrier body wall 13. Subsequently, the flow paths 11 flow between the wall elements 7, 8, 9, namely a first flow path 11 between the wall element 8 and the wall element 7 and a second flow path 11 between the wall element 9 and the wall element 7. The wall element 7 is inserted essentially centrally into the carrier body wall 13 and has, with respect to the longitudinal section of the Figure 3 the shape of an approximately isosceles triangle with concave sides. In detail, the wall element 7 is Figure 5The wall element 7 continues the curvature of the support body wall 13 through its concave wall surfaces 10 and forms, with the opposite wall element 8 or wall element 9, a flow path 11 with a substantially constant opening cross-section. A tip of the wall element 7 adjoins seamlessly the sound reduction wall 15, which is also inserted into the support body 12 and which Figure 8 is shown in more detail.

[0028] After passing through the wall element 7, the flow paths 11 continue to flow between, on the one hand, the wall element 8 and the sound-reducing wall 15, and, on the other hand, the wall element 9 and the sound-reducing wall 15. The flow paths 11 then initially run parallel to a wall plane 16 of the sound-reducing wall 15 and then continue to flow around the respective curved wall element 8, 9, thus again resulting in a flow deflection. Overall, the flow paths 11 in the sound-damping device 6 thus essentially form an S-shape or Z-shape. The curved course of the respective flow paths 11 results in the maximum number of interactions between the guided air flow and the absorbing material of the wall elements 7, 8, 9.The sound reduction wall 15 also comprises a sound-absorbing material, namely preferably a fiber-reinforced nonwoven fabric, which here is reinforced, for example, to approximately 30% (by volume) with glass fibers or carbon fibers. The wall thickness of the sound reduction wall 15 is, for example, less than 4 mm. The sound reduction wall 15 can be designed to be permeable to air, so that the air components from the flow paths 11 running parallel to the wall plane 16 of the sound reduction wall 15 can, if necessary, pass into one another. This ensures that the pressure loss within the flow channel 15 is as low as possible and thus the overall efficiency of the sound dampening device 6 (sound reduction: pressure loss) is as high as possible. The flow paths 11 have a cross-sectional area between the wall plane 16 of the sound reduction wall 15 and the wall element 8 orThe wall element 9 each has a width corresponding to approximately one-quarter of the wavelength of a sound component to be attenuated. This ensures that the center plane of the sound reduction wall 15 lies at the peak of the sound velocity of a resonance mode (the dominant sound component).

[0029] A cross section through the flow channel 5 with the sound damping device 6 is shown in Figure 4 The view is oriented parallel to the wall plane 16 of the sound reduction wall 15 in the direction of the fan 3. The flow paths 11 running parallel on both sides of the sound reduction wall 15 can be seen, which come from the direction of the central wall element 7. As can be seen in particular from Figure 3 and the design of the wall elements 7, 8, 9 according to the Figures 5 to 7As can be seen, it is essential that the flow path 11 is as curved as possible, rather than angular. This ensures that the pressure losses caused within the flow channel 5 are kept as low as possible. In addition, the sound reduction effect is enhanced by the curvature and the material of the absorbing wall elements 7, 8, 9, as well as the material of the absorbing sound reduction wall 15, so that the efficiency of the sound dampening device 6 is as high as possible.

Claims

1. Domestic appliance (1), in particular a floor cultivating appliance, having an appliance housing (2), a fan (3) arranged in the appliance housing (2), an outlet opening (4) formed in the appliance housing (2) behind the fan (3) in the direction of flow, a flow duct (5) which connects the outlet opening (4) to the fan (3) in a flow-guiding manner, and a sound damping device (6) associated with the flow duct (5) for damping sound generated by operation of the domestic appliance (1), wherein the sound damping device (6) has a plurality of sound-absorbing wall elements (7, 8, 9), which together form at least one section of the flow channel (5), wherein the wall elements (7, 8, 9) have a wall surface (10) which is curved with respect to a direction of a longitudinal extension of the flow channel (5) and are positioned relative to one another in such a way that a flow path (11) formed between opposing wall surfaces (10) extends in a curved manner, wherein the sound-absorbing device (6) has a carrier body (12) for receiving the sound-absorbing wall elements (7, 8, 9), characterised in that the flow channel (5) has a sound-reducing wall (15), wherein a wall plane (16) of the sound-reducing wall (15) is orientated parallel to the flow path (11) and wherein the sound-reducing wall (15) is arranged centrally between the opposing wall surfaces (10) of the flow channel (5) with respect to a direction orthogonal to the longitudinal extent of the flow channel (5), and wherein the carrier body (12) together with the wall elements (7, 8, 9) and the sound-reducing wall (15) forms an installation module which can be installed as a whole in the appliance housing (2), namely between the fan (3) and the outlet opening (4) of the appliance housing (2).

2. Domestic appliance (1) according to claim 1, characterised in that the flow path (11) is S-shaped, so that the flow path (11) is reversed in direction at least twice within the flow channel (5).

3. Domestic appliance (1) according to claim 1 or 2, characterised in that the flow channel (5) between the opposing wall elements (7, 8, 9) has a constant flow cross-section along the flow path (11).

4. Domestic appliance (1) according to one of the preceding claims, characterised 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 a flow channel section which is closed in an airtight manner to the outside and which is connected in an airtight manner on the one hand to the fan (3) and on the other hand to the outlet opening (4) of the appliance housing (2).

5. Domestic appliance (1) according to one of the preceding claims, characterised in that the wall elements (7, 8, 9) are formed from an open-pored foam.

6. Domestic appliance (1) according to one of the preceding claims, characterised in that the wall elements (7, 8, 9) are made of melamine resin foam or polyurethane foam.

7. Domestic appliance (1) according to one of the preceding claims, characterised in that the wall elements (7, 8, 9) have a wall thickness (d) which corresponds to at least a quarter of a wavelength of a sound component to be attenuated.

8. Domestic appliance (1) according to one of the preceding claims, characterised in that the wall elements (7, 8, 9) have an airtight sealing wall on their outwardly facing outer side (14) facing away from the guided air flow.