Abstract:
The invention relates to a sound-absorbent element for an air outlet, said air outlet comprising a housing with an air outlet opening and a connection to an air supply shaft, at least one sound-absorbent element being mounted in said housing and/or a housing of the air supply shaft, and said sound-absorbent element comprising a carrier that is connected to at least one layer of sound-absorbent material. Said at least one layer of sound-absorbent material comprises activated carbon, or at least one additional layer of activated carbon is applied to this layer of sound-absorbent material.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a sound-absorbing element for an air vent, wherein the air vent comprises a housing with an air outlet opening and a connection to an air supply shaft, wherein at least one sound-absorbing element is mounted in the housing and/or a housing of the air supply shaft and wherein the sound-absorbing element comprises a support connected with at least one layer of sound-absorbing material. 
     A range of measures and devices for reducing noise in air vents is known from the prior art. Thin and easily movable parts are frequently mounted in such air vents, which parts are set into oscillation by the exiting air flow and therefore create disturbing noise. Particularly in the case of a motor vehicle, such disturbing noises also arise as a consequence of vibration of parts of the vehicle or in the event of travel on, for example, uneven ground, which equally leads to undesired vibration or movement of the thin components of an air vent. On the other hand, flow noise also arises due to the fact that air guide elements represent resistance to the air flow, particularly when they are in extreme settings (for example, vertical slats at 45° to the flow direction so as to deflect outflowing air). 
     Thus, horizontal slats, vertical slats or closure flaps are known from, for example, EP 1 826 043 B1, which have a straight front or back edge going over into an area section which is three-dimensionally curved in wave shape. 
     Moreover, an air nozzle for guidance of an air flow from an air supply shaft is known from DE 20 2006 006 409 U1, wherein a closure flat, slats or inserts for deflecting exiting air flow is or are arranged in the housing of the air supply shaft and wherein the surfaces of the closure flap and/or the surfaces of the slats or inserts and/or the housing inner surfaces are at least partly coated with a layer of soft sound-absorbing material. The sound-absorbing materials can be foamed materials or textile materials. 
     It is possible to reduce disturbing noise by way of the constructions indicated in DE 20 2006 006 409 U1. 
     However, the layer of DE 20 2006 006 409 U1 does not produce an improvement in air quality. Complex filter devices are known for the purpose of, for example, improving the air quality of the air which is output from an air-conditioning installation of a motor vehicle. In these filter devices the air conducted into the passenger compartment is purified before output. For that purpose, these filter devices are, for example, arranged in the region of a glove box (DE 694 00 122 T2) or spaced further from a dashboard having air vents. These arrangements allow simple access to these filter devices. However, the air covers a lengthy path from these filter devices to the air outlet opening of an air vent. In addition, these filter devices need a not insignificant installation space. 
     DE 102 61 081 B3 discloses an air guide element, particularly an air guide channel for a motor vehicle, with a reverberative channel body which is produced from plastics material and which has at least one wall region replaced by a sound-absorbing component, wherein the sound-absorbing component has an at least partly exposed outer side. The plastics material of the channel body is injection-moulded around an edge region of the sound-absorbing component in such a way that the sound-absorbing component is mechanically positively connected at least in sections along its circumference with the channel body. 
     DE 103 43 96 A1 discloses a flap, particularly for an air channel of a motor vehicle ventilating system, by which the air flow in the air channel is regulated, for which purpose the flap can adopt different settings in the air channel, wherein the flap has an air-permeable region and an air-impermeable region. 
     DE 197 05 629 A1 discloses a device for reducing the noises emanating from components of a heating or air-conditioning installation for motor vehicles and transmitted into the passenger compartment, with an air flap furnished with sound-damping material, wherein the air flap is an auxiliary flap arranged within the air circulation channel and the auxiliary flap substantially consists of air-permeable material. 
     DE 91 00 514 U1 discloses an air guide element, particularly ventilation nozzle for a motor vehicle, with a shape-stable, reverberative plastics-material channel body preferably of polypropylene, wherein a wall region of the channel body is partially replaced by a non-reverberative insulating part and the non-reverberative insulating part consists of melamine-resin foamed material. 
     DE 42 44 906 C2 discloses a fan for a motor vehicle air-conditioning installation. The fan comprises a fan-wheel housing and a sound-absorbing element. The sound-absorbing element is arranged in the fan-wheel housing so as to divide the interior thereof into a first chamber and a second chamber. The first chamber has an air inlet and an air outlet and receives a fan wheel. The second chamber receives a motor, which is so connected with the fan wheel that the fan wheel is driven by the motor to allow air to flow through the first chamber. The fan-wheel housing is provided with a motor cooling air channel formed integrally with the fan-wheel housing. In addition, the motor cooling air channel extends between the first chamber and the second chamber via the sound-absorbing element so as to introduce motor cooling air from the first chamber to the motor in the second chamber. 
     DE 100 47 068 A1 discloses a filter for removing constituents from an air flow, which is conducted in a channel, of a heating or air-conditioning installation of a motor vehicle. The filter consists of at least two filter layers having a mutual spacing in flow direction so that an intermediate space is formed between the filter layers. The spacing between the filter layers corresponds with approximately a quarter of a predetermined sound wave length. The filter is thus also acoustically active and contributes to sound damping. 
     A device for acoustic insulation is known from DE 200 16 255 U1. The device comprises a housing in which insulating material is arranged. The housing for its part is provided with air passage openings and the insulating material arranged in the housing consists, at least to 50%, of sheep virgin wool. 
     An air guide channel for ventilating, heating and/or air-conditioning a vehicle interior space is known from DE 10 2005 026 556 A1. The air guide channel has a channel wall which is made at least partly of a flexible material. The flexible material comprises a non-woven material and regions which enable a defined air output are formed in the channel wall. 
     The object of the present invention is therefore to reduce or suppress noise from an air vent and at the same time improve the quality of the output air. 
     SUMMARY OF THE INVENTION 
     In the case of a sound-absorbing element for an air vent, wherein the air vent comprises a housing with an air outlet opening and a connection to an air supply shaft, wherein at least one sound-absorbing element is mounted in the housing and/or a housing of the air supply shaft and wherein the sound-absorbing element comprises a support connected with at least one layer of sound-absorbing material, the at least one layer of sound-absorbing material comprises activated carbon or at least one further layer of activated carbon is applied to the layer of sound-absorbing material. 
     The additional introduction of activated carbon into the at least one layer or the application of at least one further layer of activated carbon produces on the one hand reduction in or suppression of noise caused by components of an air vent (slats, closure flap, air guide elements) and on the other hand purification of the air flowing out of the air vent. In particular, no additional installation space for filter devices is needed for this purpose and the air is purified in the region disposed directly in front of the passenger compartment. 
     In addition, the embodiment according to the invention is advantageous with respect to weight reduction, since not only does the sound-absorbing material (for example foamed material) have a lower weight than, for example, rubber lips which are known from the prior art and which are mounted on slats for avoidance of disturbing noise due to hitting against other parts, but also activated carbon has a lower density than conventional plastic materials for slats. 
     The at least one layer can in that regard be applied over an area to at least one side of the support. In this connection “area” signifies that the at least one layer substantially completely covers the side of the support or leaves free only a defined region (for example an encircling edge). 
     Moreover, a layer can be applied to both sides of the support. 
     Moreover, the support can have at least one seat in which the layer is so received that the layer is aligned with the region of the support surrounding the seat. This construction is suitable particularly for an embodiment in which the support is of two-dimensional construction. 
     The at least one layer can consist of foamed material, wherein activated carbon is introduced into the foamed material or the foamed material is coated with activated carbon. The activated carbon can be absorbed in different volume or weight proportions into the foamed material and be present in the foamed material in different forms. Alternatively, the foamed material can be coated over the whole area with the activated carbon. The coating with activated carbon can be carried out in different ways (for example gluing or mounting on the foamed material layer by means of a net or grid connected with the support). 
     The foamed material can, in further embodiments, be of open-pore construction. Open-pore foamed materials provide improved sound absorption and offer a larger surface. A larger surface can significantly improve purification of the air particularly through the activated carbon particles absorbed in the foamed material or through a coating with activated carbon. 
     In further forms of embodiment the at least one layer can also consist entirely of activated carbon. The activated carbon can in that regard similarly be attached to the support by way of a net or grid or otherwise be applied over the whole area to an areal support. 
     The support can have passages, openings or a support structure in the region of the layers. In that case, the weight of the sound-absorbing element is reduced. Advantageously, the outflowing air flows not only past the layer, for example, non-woven material, of sound-absorbing material with activated carbon, but additionally flows through this, as a result of which the cleaning action is further improved. 
     The sound-absorbing element can be a slat of an air vent, a closure flap of an air vent, an air guide element of an air supply shaft and/or at least a part of the housing of the air vent and/or of the air supply shaft. 
     The at least one layer can have an open-pore surface. In this embodiment not only the foamed material can be of open-pore construction, but also the at least one layer, which can consist solely of activated carbon or consist of activated carbon present in or at the sound-absorbing material. 
     The surface of the at least one layer can, in addition, have a regular or irregular surface structure. Surface structures additionally enlarge the surface, which has a positive effect particularly on noise reduction/absorption and air purification. For that purpose, propagation of soundwaves can be selectively prevented by specific surface structures. Regular and irregular structures comprise, inter alia, honeycombs, grooves, openings and elevations as well as further measures enlarging the surface. 
     The at least one layer can be thermally deformed. In particular, surface forms are created in correspondence with the field and purpose of use (for example, slat) when mounting on a frame-shaped support. Aerodynamically streamlined surfaces can thereby be created in simple mode and manner by the layers. 
     The at least one layer can be constructed in such a way that in air flow direction it has a greater thickness facing the air outlet opening than in the section facing the air supply shaft. A different thickness distribution of that kind produces an improved noise reduction or suppression and a defined air guidance. 
     Moreover, the further layer can be received in a support frame and the support frame connected with the support. A support frame can be, for example, reticular means, a grid or a so-called cage. 
     The at least one layer can be glued or welded to the support and/or a second layer. 
     Flocked materials and textile materials are also usable, in particular, as sound-absorbing materials for the sound-absorbing element. 
     Further advantages, features and possibilities of embodiment are evident from the following description of figures with respect to the associated drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments illustrated in the figures are not to scale and can, in the case of forms of embodiment to be implemented, differ from the illustration. 
       In the drawings: 
         FIG. 1  shows a schematic view of a support for a sound-absorbing element in a first form of embodiment; 
         FIG. 2  shows a schematic view of a support for a sound-absorbing element in a second form of embodiment; 
         FIG. 3  shows a schematic view of a support for a sound-absorbing element in a third form of embodiment; 
         FIG. 4  shows a schematic view of a sound-absorbing element of the first form of embodiment; 
         FIG. 5  shows an exploded drawing of a sound-absorbing element of the first form of embodiment in schematic view; 
         FIG. 6  shows a schematic view of a sound-absorbing element of the second form of embodiment; 
         FIG. 7  shows an exploded drawing of a sound-absorbing element of the second form of embodiment in schematic view; and 
         FIG. 8  shows a schematic view of an air vent and an air supply shaft with different sound-absorbing elements. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The same parts are provided in the figure description of  FIGS. 1 to 8  with the same reference numerals insofar as they substantially correspond with one another in function and form thereof. 
       FIG. 1  shows a schematic view of a support  12  for a sound-absorbing element  10  in a first, not-claimed form of embodiment. The support  12  is constructed as a component of a vertical slat of an air vent  30  (not illustrated in  FIG. 1 ). The support  12  has two bearing pins  18  by way of which the vertical slat or the support  12  is rotatably mounted in a housing  31  of the air vent  30 . In addition, the support  12  has a pin  20 , wherein a plurality of vertical slats or supports  12  are pivoted by way of their pins  20  and by way of a coupling rod interconnecting the pins  20 . The support  12 , which is constructed as a frame, has an inwardly disposed step  22  to which a layer  14  with sound-absorbing material is applied. The frame  12  preferably has a step of that kind on both sides so that a layer of sound-absorbing material can be applied to the support  12  at both sides and connected with the support  12 . The region  23  surrounded by the step  22  and the support  12  constructed as a frame is left free so that depending on the thickness of the step  22  the layers  14  mounted on the two sides of the support  12  bear directly against one another or are arranged at a spacing from one another. 
       FIG. 2  shows a schematic view of a support  12  for a sound-absorbing element  10  of a second form of embodiment. The support  12  illustrated in  FIG. 2  is constructed substantially as a component of a vertical slat for an air vent  30  (not illustrated in  FIG. 2 ). The support  12  has two bearing pins  18  by way of which the support  12  or the vertical slat is rotatably mounted in a housing  31  of an air vent  30 . In addition, the support  12  or the vertical slat has a pin  20 , wherein a plurality of vertical slats or supports  12  is pivotable in common by way of a coupling rod connecting the pins  20  of the vertical slats. By contrast to the embodiment shown in  FIG. 1 , the support  12  of  FIG. 2  does not have a free region  23 , but has a seat  24  defining an area. A layer  14  of sound-absorbing material is applied to the areal seat  24 . A layer  14  is preferably applied not only to the front side, which is illustrated in  FIG. 2 , of the seat  24 , but also to the rear side of the seat  24 . The encircling part of the support  12 , which surrounds the seat  24 , protrudes beyond the seat  24  by a defined amount which is selected, in particular, to be of such a size that a deposited layer  14  is aligned with the encircling part of the support  12 . 
       FIG. 3  shows a schematic view of a support  12  for a sound-absorbing element  10  in a third form of embodiment. The support  12  illustrated in  FIG. 3  is also constructed as a vertical slat of an air vent  30 . The support  12  has bearing pins  18  by way of which the support  12  or the vertical slat is rotatably mounted in a housing  31  of the air vent  30 . In addition, the support  12  or the vertical slat has a pin  20 , wherein a plurality of supports  12  or vertical slats is pivotable in common by way of a coupling rod interconnecting the pins  20  of the vertical slats. By contrast to the supports  12  shown in  FIGS. 1 and 2  the support  12  of  FIG. 3  is constructed so that it has a structure  16  in the region in which the layer  14  of sound-absorbing material is applied. The structure  16  can be of grid-shaped construction, as illustrated in  FIG. 3 . Such a structure has a plurality of strips extending horizontally and vertically or at right angles to one another, in which case passages are present between the strips. The structure  16  serves for, inter alia, weight reduction of the support  12 . A layer  14  of sound-absorbing material can be applied to, in particular, the structure  16  on both sides of the support  12 . 
       FIG. 4  shows a schematic view of a sound-absorbing element  10  of the first form of embodiment. In distinction from the support  12  illustrated in  FIG. 1 , a layer  14  applied to the step  22  is also illustrated. The layer  14  is glued at the edge regions thereof onto the step  22 , but a different connection is also possible. In particular, a layer  14  of sound-absorbing material is applied on either side of the support  12  to the step  22  and the opposite step (not illustrated in  FIG. 4 ). 
       FIG. 5  shows an exploded drawing of a sound-absorbing element of the first form of embodiment in schematic view. The layers  14  have a defined thickness, wherein in the first form of embodiment the layers  14 —in the state of connection with the support  12  constructed as a frame—protrude beyond the support  12  by a specific amount. The layers  14  consist of a sound-absorbing material. In particular, the sound-absorbing material of the layers  14  is a foamed material, the activated carbon particles being incorporated in or applied to the foamed material. The foamed material can also be completely coated with activated carbon so that the outwardly protruding surface of the layer  14  or of the layers  14  is covered with activated carbon. Moreover, by contrast to the illustration in  FIGS. 4 and 5 , the thickness of the layers  14  can vary. Thus, the layers  14 , in air flow direction, can have a greater thickness towards an air outlet opening of the air vent  30  than in the section towards an air supply shaft  32  (not illustrated in  FIGS. 4 and 5 ). 
     It is particularly advantageous if the surface of the layers  14  is of open-pore form. In the case of the embodiments illustrated in the figures the layers  14  each have a smooth surface. However, this is merely a consequence of the schematic illustration, there being no limitation to the illustrated embodiments. 
     An open-pore surface can be formed by regular or irregular structures. Moreover, patterns such as, for example, honeycombs or alternating depressions and elevations can be provided. Beyond that, in further forms of embodiment the layers  14  can be constructed so that the foamed material is of open-pore construction in such a way that an air flow through the material of the layers  14  is possible. 
       FIG. 6  shows a schematic view of a sound-absorbing element  10  of the second form of embodiment. In the case of the sound-absorbing element  10 , which is illustrated in  FIGS. 6 and 7 , of the second form of embodiment ( FIG. 2 ) in each instance a thin layer  14  is glued to the seat  24  on either side  13  of the support  12 . The height by which the encircling part of the support  12  protrudes above the seat  24  is selected to be such that in the state of connection with the layers  14  of sound-absorbing material the surface of the layers  14  is aligned with the encircling region of the support  12 . As already indicated for  FIGS. 4 and 5 , the layer  14  can consist of a foamed material and additionally comprise activated carbon. The activated carbon can be applied entirely to the layer  14  or be present as a constituent in the layer  14 . Moreover, the layer  14  can also be formed entirely of activated carbon. For example, activated carbon particles are glued onto the seat  24  over the whole area. Noise reduction or elimination and air purification are thereby produced by the activated carbon. 
       FIG. 7  shows an exploded drawing of a sound-absorbing element  10  of the second form of embodiment in schematic view. 
       FIG. 8  shows a schematic view of an air vent  30  and an air supply shaft  32  with different sound-absorbing elements. The air vent  30  comprises a housing  31 . The housing  31  of  FIG. 8  is of substantially rectangular cross-section and has an air outlet opening  26 . The air flowing out of the air outlet opening  26  is supplied by way of the air supply shaft  32 , which similarly has a housing  33  and is connected with the air vent  30  by way of the connection  28  thereof. 
     The air fed through the air supply shaft  32  is deflected by way of air guide elements  40  and also flows along the surface of the air supply channel  32 , wherein the air supply channel  32 , through its curvature, also produces a deflection. A closure flap  38  serves the purpose of completely blocking the cross-section of the air vent  30 , in which case depending on the setting of the closure flap  38  the quantity of outflowing air as well as the issue of air is set. Vertically extending slats  36  serve for deflecting the air around the pivot axes of the slats  36 , which extend through the bearing pins  18  of the slats  36 . Horizontally extending slats  34  serve for deflecting the air perpendicularly to the vertically extending slats  36 . The horizontally extending slats  34  have bearing pins  42  by way of which the slats  34  are pivotably mounted in the housing  31  of the air vent  30 . The slats  34  can be connected by way of coupling elements so that when pivotation of one slat  34  takes place the other slats  34  execute a corresponding movement. 
     The slats  36  are similarly rotatably mounted in the housing  31  of the air vent  30  by way of the bearing pins  18  and coupled together by way of a coupling rod and the pins  30  to be pivotable in common. The closure flap  38  is pivotably mounted in the housing  31  of the air vent  30  by way of the bearing pins  44  and can be pivoted by way of a device (not illustrated in  FIG. 8 ). 
     The air guide elements  40  are mounted in the housing  33  of the air supply shaft  32  by way of bearing pins  46 . By contrast to the other means (slats  34 , slats  36  and closure flap  38 ), the air guide elements  40  cannot be pivoted. 
     In the example illustrated in  FIG. 8  the slats  34 , slats  36 , closure flap  38  and air guide elements  40  each have layers  14  of sound-absorbing material. The layers  14  are in that case applied to both sides of the slats  34 , slats  36 , closure flap  38  and air guide elements  40 . The embodiment shown here is only by way of example. Thus, the layers  14  can also be applied only to one group of slats  34  or  36  or the closure flap  38  or the air guide elements  40  or to several of the components listed above, but not all these components. 
     It is additionally possible to coat at least one wall of the housing  31  of the air vent  30  or of the housing  33  of the air supply shaft  32  with a layer  14  of sound-absorbing material. The layers  14  of sound-absorbing material comprise activated carbon or are completely coated with activated carbon or consist of activated carbon, so that on the one hand a reduction in and elimination of disturbing noise and on the other hand air purification of the outflowing air are achieved. 
     An air vent  30  of that kind and an air feed shaft  32  of that kind can, for example, be arranged in a motor vehicle. By comparison with known systems it is possible to dispense with filter devices, which need a large amount of installation space and produce purification of the air at a distance from the air outlet opening  36 . 
     REFERENCE NUMERAL LIST 
     
         
           10  sound-absorbing element 
           12  support 
           13  side 
           14  layer 
           16  structure 
           18  bearing pin 
           20  pin 
           22  step 
           23  region 
           24  seat 
           26  air outlet opening 
           28  connection 
           30  air vent 
           31  housing 
           32  air feed shaft 
           33  housing 
           34  slat 
           36  slat 
           38  closure flap 
           40  air guide element 
           42  bearing pin 
           44  bearing pin 
           46  bearing pin