HOUSEHOLD APPLIANCE WITH A SOUND ABSORPTION DEVICE

Abstract

A household appliance, particularly a floor treatment appliance, has an appliance housing, a fan arranged in the appliance housing, an outlet opening formed in the appliance housing downstream of the fan, a flow channel connecting the outlet opening to the fan in a flow-conducting manner, and a sound absorption device assigned to the flow channel in order to absorb sound generated by the operation of the household appliance. In order to create a sound absorption device that can be installed into the household appliance in a particularly simple manner, the sound absorption device comprises a plurality of sound-absorbing wall elements and a carrier body that accommodates the wall elements in a reversible manner, wherein a flow path is formed within the carrier body between opposing wall elements.

Claims

1. A household appliance comprising: an appliance housing, a fan arranged in the appliance housing, an outlet opening formed in the appliance housing downstream of the fan, a flow channel connecting the outlet opening to the fan in a flow-conducting manner, and a sound absorption device assigned to the flow channel in order to absorb sound generated by the operation of the household appliance, wherein the sound absorption device comprises a plurality of sound-absorbing wall elements and a carrier body that accommodates the wall elements in a reversible manner, wherein the wall elements are connected to the carrier body such that they can be removed without being destroyed, and wherein a flow path is formed within the carrier body between opposing wall elements.

2. The household appliance according to claim 1, wherein the carrier body and the wall elements jointly form at least a section of the flow channel.

3. The household appliance according to claim 1, wherein the wall elements have a wall surface that is curved in a direction of a longitudinal extent of the flow channel, and wherein the wall elements are positioned relative to one another by means of the carrier body in such a way that the flow path extends in a curved manner.

4. The household appliance according to claim 1, wherein the flow path is designed in an s-shaped manner such that the flow channel has at least two direction reversals.

5. The household appliance according to claim 1, wherein the flow path has a constant flow cross section.

6. The household appliance according to claim 1, wherein the carrier body has a carrier body wall at least in a section of the carrier body, and wherein the carrier body wall and the wall elements inserted into the carrier body form a flow channel section that is closed outward in an airtight manner and connected to the fan and to the outlet opening of the appliance housing in an air-sealing manner.

7. The household appliance according to claim 1, wherein the wall elements are made of an open-pored foam.

8. The household appliance according to claim 1, wherein the wall elements have a wall thickness (d) that corresponds to at least one-fourth of a wavelength of a sound portion to be absorbed.

9. The household appliance according to claim 1, wherein the wall elements have a wall that produces an airtight seal on their outwardly directed outer side facing away from a conducted air flow.

10. The household appliance according to claim 1, wherein 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 opposing wall surfaces of the flow channel in a direction extending orthogonal to the longitudinal extent of the flow channel.

11. The household appliance according to claim 1, wherein the household appliance is a floor treatment appliance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0020] In the drawings,

[0021] FIG. 1 shows an inventive household appliance;

[0022] FIG. 2 shows a carrier body for holding wall elements;

[0023] FIG. 3 shows a wall element according to a first embodiment;

[0024] FIG. 4 shows a wall element according to another embodiment;

[0025] FIG. 5 shows a wall element according to another embodiment;

[0026] FIG. 6 shows a sound reduction wall;

[0027] FIG. 7 shows a schematic representation of a flow channel with curved wall elements;

[0028] FIG. 8 shows a longitudinal section through a flow channel with a sound absorption device comprising a carrier body and wall elements inserted therein; and

[0029] FIG. 9 shows a cross section through the flow channel according to FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] FIG. 1 shows an example of a potential embodiment of an inventive household appliance 1 in the form of a floor treatment appliance. In this example, 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 that is separably connected to the base unit 18. In this example, the attachment 19 is a suction nozzle with a suction mouth 20 and a floor treatment element 21 assigned to the suction mouth 20. The base unit 18 of the household appliance 1 has an appliance housing 2, in which a vacuumed material chamber 17 and a fan 3 are located among other things. A flow channel 5 connects an output side of the fan 3 to an outlet opening 4. The fan 3 serves for vacuuming up dust and dirt into the vacuumed material chamber 17, wherein dust and dirt located on a surface to be cleaned can be vacuumed up into the vacuumed material chamber 17 of the base unit 18 through the suction mouth 20 of the attachment 19. The dust and dirt remains within the vacuumed material chamber 17 whereas cleaned air flows to the outlet opening 4 of the household appliance 1 through the fan 3 and the flow channel 5.

[0031] The base unit 18 of the household appliance 1 furthermore has a shaft 23 with a handle 22. A switch 24 is arranged on the handle 22 and enables the user to adjust a certain operating mode of the household appliance 1, e.g. an intensity level of the fan 3 and/or a rotational speed of the floor treatment element 21 of the attachment 19.

[0032] The operation of the fan 3 generates sound that is carried to the outlet opening 4 via the flow channel 5 and ultimately into the surroundings of the household appliance 1. In order to realize the household appliance 1 in such a way that its use is agreeable for a user, the household appliance 1 is equipped with a sound absorption device 6 that is illustrated in greater detail in the additional figures (see particularly FIG. 8). The sound frequencies emitted by the fan 3 are dependent on different parameters, e.g. a rotational speed of a motor shaft of the fan 3. In this context, a so-called blade pass frequency of the fan 3, which is defined by the rotational speed of the motor shaft on the one hand and the number of fan blades of the fan 3 on the other hand, is of particular interest. The sound absorption device 6 therefore is designed, in particular, for absorbing the characteristic sound frequencies of the fan 3 of the household appliance 1, which are generated at certain power settings of the fan 3.

[0033] The sound absorption device 6 has a carrier body 12 that is illustrated in FIG. 2 and a plurality of wall elements 7, 8, 9 (FIGS. 3 to 5), wherein the sound absorption device is additionally provided with a sound reduction wall 15 (FIG. 6) in this example. The wall elements 7, 8, 9 are held in the appliance housing 2 of the household appliance 1 by means of the carrier body 12. The wall elements 7, 8, 9 and the sound reduction wall 15 are inserted or plugged into corresponding receptacles of the carrier body 12, namely in such a way that no gaps or openings, through which air can escape, are formed between the material of the carrier body 12 and the wall elements 7, 8, 9. The carrier body 12 is made of a rigid plastic such as ABS or PP.

[0034] The wall elements 7, 8, 9 are foam elements of an acoustically active open-pored foam such as melamine resin foam or polyurethane foam. The wall elements 7, 8, 9 have an outer side 14 of a sound-insulating material such that the sound waves entering the pores of the wall elements 7, 8, 9 cannot exit the wall elements 7, 8, 9 on the rear side, i.e., via the outer side 14, but the non-absorbed portions of the sound wave rather are reflected back into a flow path 11 formed between opposing wall elements 7, 8, 9 in order to subsequently enter an opposite wall element 7, 8, 9 again. The wall elements 7, 8, 9 have a certain wall thickness d. The wall thickness d defines 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. In order to enable the wall element 7, 8, 9 or its absorbing material to optimally absorb a sound wave with a defined frequency, it is necessary that the wall thickness d corresponds to at least one-fourth of the wavelength of the respective sound portion. In this way, a maximum of the sound particle velocity of the respective sound portion lies within the absorbing material of the wall element 7, 8, 9. The sound particle velocity of a sound wave standing between opposing wall elements 7, 8, 9 has an amplitude of 0 on the reflective outer side 14 of the wall element 7, 8, 9 and continues to the opposite wall element 7, 8, 9 in the form of a standing sine wave, namely likewise 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 still lies within the absorbing material of the wall element 7, 8, 9 such that as much sound energy as possible is absorbed within the pores of the material and not returned back into the flow path 11.

[0035] FIGS. 7 to 9, in particular, show that the flow channel 5 within the carrier body 12 of the sound absorption device 6 is formed by a plurality of curved wall elements 7, 8, 9 in such a way that the flow path 11 formed between the wall elements 7, 8, 9 extends in a curved manner, that the sound portions impinge on a wall surface 10 of the wall elements 7, 8, 9 as frequently as possible while passing through the flow path 11, and that the energy of the respective sound portion is reduced further with each reflection on a wall element 7, 8, 9. This is achieved in that the portion of the sound energy absorbed by the material of the wall element 7, 8, 9 increases in absolute terms with the number of reflections.

[0036] It is furthermore advantageous to specify a minimum flow cross section for the clear flow cross section of the flow path 11 between the wall elements 7, 8, 9. In practical applications, the minimum cross section should referred to the value of the square of the volume flow amount to at least 0.96 x the square of the volume flow. This minimum flow cross section of the flow path 11 preferably is constant along the flow path 11, i.e. ideally from the fan 3 up to the outlet opening 4 in the appliance housing 2. In this way, the pressure loss within the flow channel 5 can be kept as low as possible and a degree of efficiency, which describes the ratio between sound reduction to pressure loss, can be improved to higher than 2:1 or even beyond.

[0037] FIG. 8 furthermore shows that the carrier body 12 is arranged in the flow channel 5 on the output side of the fan 3, namely between the fan 3 and the outlet opening 4. In this example, the carrier body 12 abuts on the inner side of the appliance housing 2 with its outer side and is fixed on the appliance housing 2, particularly by means of a screw connection, a plug connection, a snap-on connection or the like. The carrier body 12 forms an installation module together with the wall elements 7, 8, 9 and the sound reduction wall 15, which is described in greater detail below, wherein said installation module can be installed into the appliance housing 2 of the household appliance 1 as a whole. The carrier body 12 comprises its own walls, e.g. the carrier body wall 13 that acts as a flow-conducting contour, and also holding elements for the wall elements 7, 8, 9 inserted into the carrier 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-conducting functions, the flow path 11 of the flow channel 5 is only formed in its entirety once the carrier body 12 is completely fitted with all wall elements 7, 8, 9, as well as the sound reduction wall 15. The exhaust air of the fan 3 arriving from the output opening of the fan 3 splits into two separate flow paths 11, which flow around the carrier body wall 13 in opposite directions on opposite sides of the carrier body 12, in FIG. 8 particularly in a direction downward and upward (referred to the plane of projection of FIG. 8). In the process, both flow paths 11 respectively undergo a change in direction by 180°, which is caused by the deflection of the exhaust flow around the outer edges of the carrier body wall 13. The flow paths 11 subsequently flow between the wall elements 7, 8, 9, namely a first flow path 11 between the wall element 8 and the wall element 7, as well as the wall element 9 and the wall element 7. The wall element 7 essentially is inserted into the carrier body wall 13 centrally and has referred to a cross section the shape of an approximately isosceles triangle with concave sides. The wall element 7 is illustrated in detail in FIG. 3. The wall element 7 extends the curvature of the carrier body wall 13 with its concave wall surfaces 10 and forms a flow path 11, which essentially extends with constant width, together with the respective opposite wall element 8 or 9. In this case, a tip of the wall element 7 seamlessly connects to the sound reduction wall 15, which is likewise inserted into the carrier body 12 and illustrated in greater detail in FIG. 6.

[0038] The flow paths 11 flow onward separately of one another between the wall element 8 and the sound reduction wall 15 on the one hand and the wall element 9 and the sound reduction wall 15 on the other hand, wherein the flow paths 11 then initially extend parallel to a wall plane 16 of the sound reduction wall 15 and then flow around the respective curved wall element 8, 9 such that the flow direction is once again deflected by approximately 180°. All in all, the flow paths therefore essentially have an s-shape or z-shape from the fan 3 up to the outlet from the carrier body 12. A maximum number of interactions between the conducted air flow and the absorbing material of the wall elements 7, 8, 9 is achieved due to the curved extent of the respective flow path 11. The sound reduction wall 15 also has a sound-absorbing material, preferably a fiber-reinforced nonwoven fabric that in this example is reinforced with approximately 30% glass fibers or carbon fibers (referred to its volume). A wall thickness of the sound reduction wall 15 amounts, for example, to less than 4 mm. The sound reduction wall 15 may be permeable to air such that the air flows from the flow paths 11 extending parallel to the wall plane 16 of the sound reduction wall 15 basically can transfer into one another. In this way, the pressure loss within the flow channel 15 is as low as possible such that the overall degree of efficiency of the sound absorption device 6 (sound reduction:pressure loss) becomes as high as possible. A respective width of the flow paths 11 between the wall plane 16 of the sound reduction wall 15 and the wall element 8 and between the sound reduction wall 15 and the wall element 9 approximately corresponds to one-fourth of the wavelength of a sound portion to be absorbed. In this way, the central plane of the sound reduction wall 15 lies in the peak of the sound particle velocity of the resonant mode (the dominant sound portion).

[0039] FIG. 9 shows a cross section through the flow channel 5 with the carrier body 12. The viewing direction in this figure extends parallel to the wall plane 16 of the sound reduction wall 15 in the direction of the fan 3. This figure shows the flow paths 11 that extend parallel to one another on both sides of the sound reduction wall 15 and arrive from the direction of the central wall element 7. According to FIG. 7, in particular, as well as the shape of the wall elements 7, 8, 9 illustrated in FIGS. 3 to 5, it is essential that the flow path 11 is as curved as possible and not angular. This ensures that the pressure losses caused within the flow channel 5 are kept as low as possible. In addition, the value of the sound reduction is increased by the material of the absorbing wall elements 7, 8, 9, as well as the absorbing sound reduction wall 15, such that the degree of efficiency of the sound absorption device 6 is as high as possible.

[0040] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.

LIST OF REFERENCE SYMBOLS

[0041] 1 Household appliance [0042] 2 Appliance housing [0043] 3 Fan [0044] 4 Outlet opening [0045] 5 Flow channel [0046] 6 Sound absorption device [0047] 7 Wall element [0048] 8 Wall element [0049] 9 Wall element [0050] 10 Wall surface [0051] 11 Flow path [0052] 12 Carrier body [0053] 13 Carrier body wall [0054] 14 Outer side [0055] 15 Sound reduction wall [0056] 16 Wall plane [0057] 17 Vacuumed material chamber [0058] 18 Base unit [0059] 19 Attachment [0060] 20 Suction mouth [0061] 21 Floor treatment element [0062] 22 Handle [0063] 23 Shaft [0064] 24 Switch [0065] d Wall thickness