EP2267373B1 - External blower for fume extraction device - Google Patents

Description

The invention relates to an external fan for a fume extraction device. In hoods usually a fan is sucked through the fumes and vapors in the hood, provided in a fan housing that is located directly above or behind the suction port. The suction opening is covered by a grease filter. However, there are also hoods, in which only a housing with a suction in the room in which the fumes and vapors arise, especially the kitchen, is provided while the blower over which the vacuum required for the suction of fumes and vapors is generated, attached to the outside of the room wall, in particular the house wall. These blowers are also referred to as external blowers and are connected to the housing in the room via piping or ducts.

These external blowers have special requirements. In particular, the volume flow carried by the blower must be greater than with a blower which is arranged directly in the vicinity of the suction opening, in order to be able to ensure reliable extraction of fumes and vapors. A disadvantage of this required volume flow is that the noise is greater. In addition, with external blowers, the areas where air can be blown out of the blower, limited because the ingress of moisture and environmental contaminants must be avoided in the housing.

In the DE 86 01 684 U1 a cooling fan for an electric machine is described. This blower is followed by the spiral housing of a radial fan to a sound-absorbing layer, in which the exhaust opening of the spiral housing is modeled. As a result, the air outlet from the volute casing is not disturbed. A disadvantage of this fan is that the air flow from the discharge opening of the volute to the air outlet from the fan continues to cause noise.

Furthermore, from the CN 201 173 515 Y a hood known, which has a main cabinet in which a fan is arranged. In the main cabinet, an inlet pipe and two air outlet pipes are provided. To reduce noise, the main cabinet is equipped with a noise isolation and noise suppression device. This device is provided on the inside of the housing and on the outside of the tube, which connects to the fan and runs in the main cabinet.

From the US 2,185,718 A Furthermore, a fan is known, which is operated at a heating, cooling or humidifying and having a noise-absorbing outlet with widening cross-section. The noise-absorbing lining of the outlet has a constant thickness.

Moreover, from the EP 0 596 846 A1 a kitchen fan is known which comprises a housing in which a fan is arranged and which has an outlet passage which has a tapered portion which is provided on both sides with sound-absorbing material. The air outlet of the area surrounding the fan is in this case directed in the flow direction to the outlet of the housing. The air exiting the fan area therefore flows directly to the outlet of the housing. Thus, it may continue to cause noise.

Object of the present invention is therefore to provide a way with which an external fan can be operated with sufficient volume flow and at the same time the operating noise of the external fan can be reduced.

The invention is based on the finding that this object can be achieved by providing a sound-damping element in the vicinity of the air outlet of the fan housing in the flow direction of the air emerging from the fan housing. This means that a blower module, in which the fan is provided, a silencer is connected downstream.

The object is therefore achieved by an external fan for a fume extraction device, which has a fan housing and a fan housing accommodated in the fan housing, wherein at least one silencing element is provided in the fan housing relative to the air outlet of the fan housing. The fan is characterized in that the Schalldämpfelement is disposed on a housing wall of the fan housing, which is opposite to the air outlet of the fan housing, and the Schalldämpfelement is at least the essential part of the exiting the fan housing air is flown and that the Schalldämpfelement has different thicknesses over its surface and the silencer member has the largest thickness at a position corresponding to the center of the air outlet of the fan housing.

For the purposes of the present invention, an external blower is a blower which is attached to an outer wall of a building or the roof of a building and is connected via a piping or a duct to at least one extractor device in a room of the building. The extractor device in the room in this case preferably has no fan, but includes an intake opening, can enter through the air to be cleaned in the extractor device. The blower housing of the external blower is the outer housing, which is directly in contact with the environment, that is, the outdoors. The blower housing generally has a box shape in which an air inlet opening in a side wall and in the bottom and / or in areas of the side walls air outlet openings are provided. As the underside of this case, the side is referred to, which in the mounted state in which the blower is fixed to a vertical wall, facing down.

The fan of the fan according to the invention preferably represents a radial fan. In this case, a pressure acceleration is achieved by the centrifugal force of the rotating fan component, which is further enhanced by the fan housing surrounding the fan. Volume flows of up to more than 1000m ³ / h can be achieved with a radial fan. The fan housing is preferably a volute housing having an air inlet on one or both sides and an air outlet at one location on the circumference. The air outlet is formed in particular by a pipe socket. The pipe socket may be part of the fan housing or as be formed separate part and be attached to the opening of the fan housing.

The silencer is arranged in accordance with the present invention so as to face the air outlet of the fan housing. This means according to the present invention that the sound-damping element in projection opposite to the air flow direction on the air outlet, the air outlet at least partially covers. However, the sound-damping element is arranged such that there is at least in part a distance between the surface of the air outlet and the sound-damping element. Preferably, the entire Schalldämpfelement is spaced from the air outlet.

By arranging a silencing element relative to the air outlet of the fan housing, it can be ensured that the essential part of the air emerging from the fan housing flows against the sound-damping element. The noise emitted by the fan noise component is detected in this case in the opposite of the air outlet Schalldämpfelement. Thereby, the air outlet noise from the fan housing can be reduced by the silencer. According to the invention, the sound-damping element completely covers this air outlet in projection onto the air outlet of the fan housing. This ensures that the entire air flow from the fan housing flows against the sound-damping element.

According to the invention, the sound-damping element is arranged on a housing wall of the blower housing, which lies opposite the air outlet of the blower housing. In this housing wall of the blower housing air outlet openings may be provided for the air outlet from the fan housing. The housing wall can also represent a closed wall. Preferably, the housing wall, on which the silencing element is provided, is parallel to the surface of the air outlet of the fan housing and thus, as a rule, perpendicular to the flow direction of the air emerging from the ventilator housing.

In the simplest case, the Schalldämpfelement represents a Schalldämpfplatte or Schalldämpfmatte. In this case, the effectiveness of the sound attenuation is influenced by the thickness of the Schalldämpfmatte because the detected by this noise spectrum depends on the thickness of the damping layer. At a small thickness For example, the noise components in the upper frequency range are primarily recorded.

According to the invention, the sound-damping element has different thicknesses over its surface. In particular, the sound-damping element may for example have a conical shape, a truncated cone shape, a wedge shape, a pyramid shape or a roof shape. In this case, one side of the sound-damping element is preferably flat. With this side, the silencer can be applied and attached to the housing wall of the blower housing. The flat side of the Schalldämpfelementes is therefore facing away from the air outlet in the installed state.

By the sound damping element having different thicknesses, a wide frequency spectrum can be detected. In addition, by the three-dimensional geometry of a Schalldämpfelementes with different thicknesses and a Luftleitfunktion be met by the silencer. In particular, the air emerging from the air outlet can be directed to air outlet openings in the blower housing. By a targeted air duct on the sound-damping element due to its geometry, the flow resistance is thus reduced in comparison to a sound-damping plate or Schalldämpfmatte. With a silencer element with different thicknesses, therefore, the sound power of the external fan can be reduced.

According to the invention, the silencer member having different thicknesses across the surface at a position corresponding to the center of the air outlet of the fan housing, the largest thickness. In a rotationally symmetrical sound-damping element and a circular air outlet, the sound-damping element and the air outlet are arranged concentrically with one another. The location corresponding to the center of the air outlet is the location which, when the sound attenuator is mounted, is perpendicularly projected to the air outlet in the center of the air outlet. As a result of this embodiment of the sound-damping element, the air emerging from the air outlet is split at the sound-damping element and is thus distributed. After splitting, the air flows along the areas of the sound-damping element of lesser thickness and can thus reach air outlet openings of the fan housing. This increases the area of the air outlet from the blower housing, whereby the exit velocity is reduced. In addition to the absorption of noise, therefore, the noise is reduced by the Schalldämpfelement.

If the silencing element has a shape in which the largest thickness of the silencer extends across the width or length of the silencer, then preferably the silencer is positioned such that the line of highest elevation passes through the location corresponding to the center of the air outlet of the fan housing , In this embodiment, the sound-damping element, for example, have the shape of a wedge or roof. At such a silencing element, the air flow emerging from the air outlet of the fan housing is divided into two partial flows, after it has impacted the silencer element. Thus, the different frequencies are detected by the Schalldämpfelement and at the same time realizes a targeted air flow.

According to a further embodiment, at least one lateral sound damping part is provided in the fan housing and forms a sound damping body with the sound damping element. The Seitenschalldämpfteil is arranged so that this lies in the vertical projection on the air outlet of the fan housing outside the surface of the air outlet. By providing Seitenschalldämpfteilen in the fan housing on the one hand additional areas are supplied for sound absorption. On the other hand, the air-guiding function is improved, since the air is now directed to the sound-damping element and the side or sound damping parts, in particular between the sound-damping element and the side sound damping part. The shape of the Seitenschalldämpfteils or Seitenschalldämpfteile here is selected depending on the shape of the Schalldämpfelementes. In particular, one or more channels are formed between the sound-damping element and the side-sound damping parts. Preferably, these channels are designed so that the channel cross-section increases from the top of the Schalldämpfkörpers to the bottom or to its sides. As a result, the outflow velocity of the air is reduced from the outlet openings of the blower housing, thereby further minimizing the noise.

According to a further embodiment, the silencing element covers the housing side of the blower housing, which is the air outlet of the blower housing opposite, completely. In this case, the area available for noise absorption can be maximized while realizing a continuous air flow from the air outlet to the sides of the device housing. Thus, the sound emitted by the fan outlet or fan nozzle sound component is better detected. Alternatively, however, the sound-damping element can cover only a part, in particular the middle part of the housing side of the blower housing, which lies opposite the air outlet of the blower housing. In this case, the edge area around the sound-damping element for air outlet openings from the blower housing is available.

The fan housing may have air outlet openings on the housing side opposite the air outlet of the fan housing and / or on housing sides adjacent thereto. The air outlet openings on the housing side, which is opposite to the air outlet and in particular the underside of the fan housing, may be distributed over the entire surface of this housing side. For example, a perforated plate can be used as the underside of the blower housing. In this embodiment, the sound-damping element is placed on the perforated plate and optionally attached to this. But it is also possible to provide only the edge region of the bottom with air outlet openings. In this case, the central region in which the air outlet openings are recessed, chosen so that it corresponds to the shape of the Schalldämpfelementes, which is to be applied to the perforated plate. On the sides of the fan housing, which are adjacent to the underside, in particular the side walls and the front of the fan housing, also air outlet openings may be provided. At these housing sides or housing walls, the air outlet openings are only in the lower region, that is provided in the vicinity of the bottom of the blower housing. The openings on the side walls and the front can also be formed by round holes. However, it is also possible to choose other opening shapes. For example, these openings may be formed by slots or by a single opening covering the entire area intended for air discharge. The air outlet openings are provided in the side walls and / or the front side, in particular in the embodiments in which the sound-damping element covers the entire housing side, which is opposite the air outlet.

According to a further embodiment, the sound-damping element has an intermediate wall which extends perpendicular to a projection in the sound-damping element. In this embodiment, the properties of the optimized air flow, the detection of a wide frequency spectrum, due to the different thicknesses of the Schalldämpfelementes caused by the survey, and the use of a partition wall are combined. Through the partition, the silencer acts like a slotted silencer. In addition, the provision of an intermediate wall leads to increased stability of the sound-damping element. As an intermediate wall in particular a wall is referred to, which extends from a flat bottom of the silencer from vertically upwards. The height of the intermediate wall can in this case correspond to the height of the elevation of the sound-damping element. As a survey, a point or a line is referred to, which has a greater height than the other areas of the Schalldämpfelementes. In particular, in a fan housing, are provided in the air outlet openings in the side walls of the blower housing, this type of Schalldämpfelement is advantageously used. The intermediate wall in this case runs perpendicular to the side walls of the blower housing.

The sound-damping element according to one embodiment consists of two shells. This structure is particularly advantageous for a sound-damping element, which should have an intermediate wall. In this case, namely, two trained as a channel halves shells can be juxtaposed and the upstanding adjacent channel sides form the intermediate wall. In addition, a metal plate can be inserted between the shells or channel halves. This further increases the stability of the Schalldämpfelementes. In the shells, geometries are preferably provided in this embodiment, in which the thickness of the sound-damping element varies over the length of the shell.

The muffler element has a symmetrical shape according to some embodiments. In particular, a mirror-symmetrical and a rotationally symmetrical shape are preferred. In addition to uniform sound absorption and targeted air flow, the production of the silencing element is simplified by the symmetry.

The silencing element is preferably provided in the vicinity of the air outlet of the fan housing. According to one embodiment, the distance between the highest point of the silencing element and the air outlet is at most one third, preferably at most one quarter, of the diameter of the air outlet. Due to the small distance to the air outlet, it is ensured that the air exiting from the air outlet reaches the sound-damping element and this can provide a noise reduction. In addition, due to the small distance to the air outlet alone through the sound damping a targeted air flow can be created because the air flow exiting the air outlet is still directed. On the other hand, with a sound damping element arranged at a greater distance from the air outlet, the air flow will already be undirected due to turbulences, as a result of which targeted air guidance through the sound damping element is made difficult or impossible.

As already described above, the fan housing may consist of a box-shaped housing and thereby be in one piece. In this case, a partition is usually provided inside the fan housing. This partition divides the interior into an upper and a lower housing area. In the upper housing area, the inlet opening for the air inlet is provided at the rear. In addition, the fan housing is accommodated in the upper area. In the partition, a passage is provided through which the air outlet of the fan housing may extend or on which the air outlet can be placed. The size of the passage corresponds to the inner or outer dimensions of the air outlet, for example a pipe socket. In the lower area of the blower housing, the sound-absorbing element, optionally with Seitenschalldämpfteilen added. In addition, air outlet openings are provided or introduced in the lower region of the housing on the underside, front side and / or the side walls.

According to an alternative embodiment, the blower housing is in two parts and a part of the blower housing accommodates the sound-damping element and has the at least one air outlet opening of the blower housing. In this embodiment, therefore forms the sound-damping element or the Schalldämpfkörper with a sheet metal housing a self-supporting element. This will be at the Bottom of the upper part of the blower housing attached. The structure of the upper part of the blower housing and the components contained therein correspond to those of the upper housing portion, which has been described with reference to the one-piece blower housing. The silencer with sheet metal housing can be used as a special accessory and can be used to retrofit existing installations. For retrofitting, only the lower separate housing part is mounted on an already existing fan housing from below.

But according to the invention it is also possible to attach a silencer element to the protective grid of an already existing, that is installed fan housing, in particular under the protective grille.

As a material for the sound-damping element and optionally the side sound damping part according to the invention, for example, foam is used.

Figur 1:

eine perspektivische Rückansicht eines Gebläses;

Figur 2:

eine schematische Schnittansicht des Gebläses nach Figur 1;

Figur 3:

eine perspektivische Rückansicht einer ersten Ausführungsform des erfindungsgemäßen Gebläses;

Figur 4:

eine schematische Schnittansicht der ersten Ausführungsform nach Figur 3;

Figur 5:

eine schematische Schnittansicht einer zweiten Ausführungsform des erfindungsgemäßen Gebläses;

Figur 6:

eine perspektivische Rückansicht einer dritten Ausführungsform des erfindungsgemäßen Gebläses;

Figur 7:

eine schematische Schnittansicht der dritten Ausführungsform nach Figur 6;

Figur 8:

eine perspektivische Rückansicht einer vierten Ausführungsform des erfindungsgemäßen Gebläses;

Figur 9:

eine schematische Schnittansicht der vierten Ausführungsform nach Figur 8;

Figur 10:

eine Perspektivansicht einer Ausführungsform eines Schalldämpfelementes des erfindungsgemäßen Gebläses;

Figur 11:

eine perspektivische Rückansicht eines weiteren Gebläses; und

Figur 12:

eine schematische Schnittansicht des Gebläses nach Figur 11

The invention will be explained again below with reference to the accompanying figures, which show different embodiments of the blower housing according to the invention. Show it:

FIG. 1:

a rear perspective view of a blower;

FIG. 2:

a schematic sectional view of the fan after FIG. 1 ;

FIG. 3:

a rear perspective view of a first embodiment of the blower according to the invention;

FIG. 4:

a schematic sectional view of the first embodiment according to FIG. 3 ;

FIG. 5:

a schematic sectional view of a second embodiment of the blower according to the invention;

FIG. 6:

a rear perspective view of a third embodiment of the blower according to the invention;

FIG. 7:

a schematic sectional view of the third embodiment according to FIG. 6 ;

FIG. 8:

a rear perspective view of a fourth embodiment of the blower according to the invention;

FIG. 9:

a schematic sectional view of the fourth embodiment according to FIG. 8 ;

FIG. 10:

a perspective view of an embodiment of a Schalldämpfelementes of the blower according to the invention;

FIG. 11:

a perspective rear view of another fan; and

FIG. 12:

a schematic sectional view of the fan after FIG. 11

FIG. 1 shows an embodiment of a blower. The Figures 3 . 6 and 8th each show a perspective rear view of embodiments of the blower according to the invention 1. The fan housing 10 has in all these embodiments, the same basic structure. The blower housing 10 has a box shape. The top 101, which may also be referred to as a lid, is inclined in the illustrated embodiment. Furthermore, the fan housing 10 includes a back or rear wall 102, two side walls 103 and a front side 105, which is not visible in the views shown. Finally, the blower housing 10 has an underside 104, which is also referred to as floor.

In the back 102 an air inlet opening 1021 is provided. To this air inlet opening 1021, which has a circular cross-section, a pipe can be connected, via which the external blower 1 with the extractor device (not shown), which is provided in a room in the building to which the external housing 1 is attached, can be connected. In the illustrated perspective views, the lower portion of the back surface 102 is not shown to allow insight into the interior of the blower housing 10. In the blower housing 10, however, the rear wall 102 will extend over the entire height of the blower housing 10, that is, up to the bottom 104 of the blower housing 10.

As can be seen from the respective sectional views 2, 4, 7, 9 and 12, the interior of the blower housing 10 is divided into upper and lower parts 10a, 10b or section. These are separated by a partition wall 11 from each other. The partition wall 11 extends in the horizontal direction and covers the entire area between the front side 105, the rear wall 102 and the side walls 103. In the partition 11, a passage 111 is provided.

In the upper part 10 a of the blower housing 10, the fan housing 2 of the fan (not visible) is arranged. The suction openings 21 of the fan housing 2 are located on the sides of the fan housing 2. The lower end of the fan housing 2 is formed by the air outlet 22. This air outlet 22 has the shape of a raw nozzle. The pipe socket extends through the passage 111 into the lower part 10 b of the blower housing 10.

When the blower, in the Figures 1 and 2 is shown, in the lower part of the blower housing 10, a silencer 3 in the form of a Schalldämpfmatte 31 on the bottom 104 and the bottom of the fan housing 10 is arranged. The Schalldämpfmatte 31 has a rectangular shape. The Schalldämpfmatte 31 is arranged so that it is at a distance from the side walls 103 of the fan housing 10. There is also a distance from the sound damping mat 31 to the front side 105 and the rear wall 102 of the blower housing 10. The sound damping mat 31 is aligned such that it lies below the air outlet 22 of the blower housing 2 in a vertical projection. In the bottom 104 of the blower housing 10, air outlet openings (not shown) are at least in the edge region, which consists between the Schalldämpfmatte 31 and the side walls 103, the front 105 and the rear wall 102 is inserted.

Air entering via the air inlet opening 1021 in the upper part 10 a of the blower housing 10 is transported through the suction openings 21 in the interior of the fan housing 2. The exiting from the fan housing 2 air passes through the air outlet 22 in the lower part 10 b of the blower housing 10. By the Schalldämpfmatte 31 is disposed opposite the air outlet 22, the air exiting from the air outlet 22 passes directly to the Schalldämpfmatte 31, the noise of a certain frequency can be absorbed. Via the air outlet openings of the blower housing 10, the air then enters the environment. The air guide of this embodiment is in FIG. 1 indicated schematically by the arrows.

According to a first embodiment, the in FIGS. 3 and 4 is shown, the sound dam element 3 in the form of a straight circular cone 32. The circular base 321 of the circular cone 32 rests on the underside 104 of the blower housing 10. The diameter of the circular cone 32 is dimensioned such that this substantially the diameter of the air outlet 22nd of the fan housing 2 corresponds. The circular cone 32 is arranged in a vertical projection under the air outlet 22 of the fan housing 2. Thus, the circular cone 32 is spaced from the side walls 103, the front side 105 and the rear wall 102. At this distance air outlet openings (not shown) are provided. In the illustrated embodiment, the circular cone 32 has the shape of a cylinder in its lower portion. The height of the circular cone 32 at its center is dimensioned such that there is a small vertical distance between it and the underside of the air outlet 22 of the fan housing 2. The air exiting from the air outlet 22 is fanned out in this embodiment due to the conical shape of the silencer 3 and distributed over the circumference of the circular cone 32. This results in a targeted air flow along the circular cone 32 to the bottom 104 of the blower housing 10, where the air via air outlet openings (not shown) can escape into the environment. Since the circular cone 32 has different heights over its base 321, it is possible to absorb this noise of different frequencies. In addition, the exit surface can escape via the air from the blower housing 10, increased due to the fanning of the air flow and thereby reduces the exit velocity. This leads to a further noise reduction.

In the second embodiment, which is in FIG. 5 is shown, in addition to the silencer 3 in the form of a circular cone 32 Seitenschalldämpfteile 33 additionally provided. These Seitenschalldämpfteile 33 are provided on the underside of the partition wall 11 along the front side 105, the rear wall 102 and the side walls 103. The Seitenschalldämpfteile 33 in this case have a wedge shape and are mounted so that the side facing the circular cone 32 is a slope. As a result, the air flow is further improved and also more surfaces for noise absorption are created.

The first and second embodiments may also be modified so that the shape of the silencer element 3 instead of a circular cone represents a wedge. In this case, the base of the silencer 3 is rectangular and the slopes of the wedge or roof extend from the center of the silencer 3 to two sides down toward the bottom 104 of the blower housing 10. The side silencers 33 in this modified embodiment are only along the Side walls 103 at the bottom of Partition wall 11 is provided. In this modified embodiment, the air flow from the air outlet 22 is split into two partial streams.

In the FIGS. 6 and 7 a third embodiment is shown. In this embodiment 10 air outlet openings 1031 are provided in the side walls 103 of the fan housing 10 in the region of the lower part 10b of the fan housing. The air outlet openings 1031 are formed in the illustrated embodiment by rectangular openings which extend to the front edge and the rear edge of the side wall 103. However, it is also possible to form the air outlet openings 1031 by perforations in the lower region of the side walls 103.

The silencer 3 has the shape of a roof 34 according to the third embodiment. The base 341 in this case covers the entire bottom 104 of the fan housing 10. The top of the roof 34 is formed by two curved roof surfaces 342, which extend to the center of the roof 34 upwards. The rooftop 343 is rounded. The rooftop 343 is located in the center of the silencer element 3 and in the vertical projection of the air outlet 22 along the diameter of the air outlet 22. The roof 34 has the greatest height in the middle. At this point, the rooftop 343 is only slightly spaced from the underside of the air outlet 22. On the sides of the roof 34, which bear against the side walls 103 of the blower housing 10, the height of the roof 34 is so small that it corresponds only to the height of the lower edge, which is formed by the air outlet opening 1031 in the side wall 103. By this construction, the air flow exiting from the air outlet 22 impinges on the rooftop 343 and is split there. Along the curved roof surfaces 342, the air is directed to the air outlet openings 1031 in the side walls 103 and can escape there. The air outlet 22 opposite surface, that is, the bottom 104 of the blower housing 10 is fully utilized in this embodiment for the use of sound-absorbing measures. In addition, since the sound absorbing member 3 has a large number of different thicknesses through the roof shape over the surface thereof, a large number of different frequencies can be absorbed by the sound absorbing member 3.

The fourth embodiment incorporated in the FIGS. 8 and 9 is shown substantially corresponds to the third embodiment, in particular, are also in the fourth Embodiment provided in the side walls 103 of the blower housing 10 air outlet openings 1031. In addition, the silencer 3 also has a roof shape. However, in the fourth embodiment, an intermediate wall 35 is provided. This intermediate wall 35 extends vertically to the base 341 of the roof-shaped Schalldämpfelementes 3 and is perpendicular to the direction of the rooftop 343. Thus, the intermediate wall 35 extends in the illustrated embodiment of a side wall 103 to the opposite side wall 103. The height of the intermediate wall 35 corresponds to the height of the silencer element 3 on the rooftop 343. Through the intermediate wall, the silencer element 3 acts like a slotted silencer. The air flow emerging from the air outlet 22 is divided by the rooftop 343 into two counterflows that run counter to one another, which in turn are divided into two further partial flows due to the intermediate wall 35. Thus, due to the intermediate wall 35 in addition to improved sound attenuation and the air flow is improved. Finally, the intermediate wall 35 gives the sound-damping element 3 a higher stability, which in particular prevents bending of the sound-damping element 3.

In FIG. 10 is another embodiment of a Schalldämpfelementes 3, which can be used in a blower 1 according to the invention shown. The sound-damping element 3 consists in this embodiment of two shells 36. The shells 36 have a U-shaped cross-section. The base of the shells 36 each represents a flat surface from which the legs of the shells 36 face upward. In the shells 36 is in each case a roof-shaped geometry corresponding to the roof shape, with reference to the FIGS. 8 and 9 was described trained. Between the adjoining legs of the two shells 36, a metal plate 37 is provided, this thus forms together with the adjacent legs of the shells 36 an intermediate wall 35. The in the FIG. 10 shown silencing element 3 is used in a fan housing 10, which, as in the FIGS. 8 and 9 shown in the side walls 103 has air outlet openings 1031. The two-part construction makes it possible to further increase the stability of the sound-damping element 3 by means of a metal sheet 37.

In the FIGS. 11 and 12 Finally, another external blower 1 is shown. In this blower 1, the silencer 3 forms part of a Schalldämpfkörpers 38. The Schalldämpfkörper 38 fills the entire lower part 10 b of the blower housing 10, that is, the area between the partition wall 11 and the bottom 104, from. The sound-damping element 3 in this case has a rotationally symmetrical shape, in particular a truncated cone shape. The diameter of the base 391 of the truncated cone 39 corresponds to the diameter of the air outlet 22 of the fan housing 2. The top of the truncated cone 39 is in this embodiment in the height of the underside of the air outlet 22 or even projects beyond the fan housing 2. Via webs 381 of the truncated cone 39 is connected to the edge portion 382 of the Schalldämpfkörpers 38. Between the edge portion 382 and the truncated cone 39 an annular channel 383 is formed, can pass through the air from the air outlet 22 via the Schalldämpfkörper 38 to the bottom 104 of the blower housing 10. In the bottom 104 air outlet openings (not shown) are provided, through which the air can escape from the fan housing 10 and can get into the environment. The annular channel 383 is designed diffuser-like. This means that the channel width at the top of Schalldämpfkörpers 38, where it rests against the air outlet 22, is less than at the bottom of the Schalldämpfkörpers 38, where it rests against the underside 104 of the fan housing 10. As it turned out FIG. 11 results in this case, the channel 383 is chosen so wide that it ends at the front 105 and the rear wall 102 of the blower housing 10. There are thus arcuate openings of the Schalldämpfkörpers 38 on the front side 105 and the rear wall 102. This makes it possible via a corresponding air outlet opening in the front side 105 to give air in addition to the outlet via the bottom 104 in the environment.

The present disclosure is not limited to the illustrated embodiments. In particular, individual features of an embodiment can be realized in another embodiment, without that all other features of the described embodiment must also be realized in the other embodiment.

In the new concept of external blowers, a silencer with a silencer element is integrated into the interior of the housing, which is located at the front Air outlet of the fan is connected or downstream of this. The escaping air must forcibly escape from the fan through the muffler, whereby the air outlet noise is reduced by the muffler used. The sound damping device is designed in such a way that the noise component emitted by the fan is detected in a sound damping medium which is opposite the outlet region.

A number of advantages can be achieved with the present invention. In particular, the advantages are in the noise reduction. Thus, the sound power level is reduced by the downstream silencer, which includes the silencer. In addition, the flow rate of the air can be selectively reduced by the design of the Schalldämpfelementes to provide an additional contribution to noise reduction.

By reducing the sound power of external fans, the following advantages are achieved. The homeowner or his neighbors are not disturbed by the high operating noise and the customer satisfaction is increased.

The silencer in no way affects the operation of the external blower, whereby only the reduction of the sound power is achieved as desired.

The element can be used as a component integrated in the device already in the delivery state of the device or as an optional accessory for retrofitting existing installations.

LIST OF REFERENCE NUMBERS

1

external fan

10

fan housing

10a

upper part

10b

lower part

101

top

102

rear wall

1021

Air inlet opening

103

side walls

1031

Air outlet opening

104

bottom

105

front

11

partition wall

111

passage

2

fan housing

21

Intake vent

22

air outlet

3

sound-absorbing

31

Schalldämpfmatte

32

circular cone

321

Floor space

33

Seitenschalldämpfteil

34

top, roof

341

Floor space

342

roof

343

rooftop

35

partition

36

Bowl

37

metal plate

38

Schalldämpfkörper

381

web

382

edge part

383

channel

39

truncated cone

391

Floor space

Claims (10)

1. External fan for an extractor device, said fan comprising a fan housing (10) and a ventilator housing (2) received in the fan housing (10), wherein at least one sound-absorbing member (3) is provided in the fan housing (2) opposite the air discharge (22) in the ventilator housing (2), wherein the sound-absorbing member (3) is arranged on a housing wall of the fan housing (2), which is opposite to the air discharge of the ventilator housing, characterised in that the sound-absorbing member (3) projects in a perpendicular manner toward the air discharge (22) in the ventilator housing (2) and covers said outlet completely, that the sound-absorbing member (3) varies in thickness over its surface and that the sound-absorbing member (3) is thickest at a point which corresponds to the centre of the air discharge (22) in the ventilator housing (2).
2. External fan according to claim 1, characterised in that at least one sound-absorbing lateral part (33) is provided in the fan housing (10) and is arranged so as to project in a perpendicular manner toward the air discharge (22) in the ventilator housing (2) outside the surface of the air discharge (22).
3. External fan according to one of claims 1 to 2, characterised in that the sound-absorbing member (3) completely covers the housing face (104) of the fan housing (10), which housing face is arranged opposite the air discharge (22) in the ventilator housing (2).
4. External fan according to one of claims 1 to 3, characterised in that the fan housing (10) comprises air outlet openings (1031) in the housing face (104) arranged opposite the air discharge (22) in the ventilator housing (2) and/or in adjacent housing faces (103, 105).
5. External fan according to one of claims 1 to 4, characterised in that the sound-absorbing member (3) comprises a partition wall (35) that extends perpendicular to an elevation (343) in the sound-absorbing member (3).
6. External fan according to claim 5, characterised in that the sound-absorbing member (3) consists of two shells (36).
7. External fan according to one of claims 1 to 6, characterised in that the sound-absorbing member (3) is rotationally symmetrical in shape.
8. External fan according to one of claims 1 to 7, characterised in that the distance between the highest point (343) of the sound-absorbing member (3) and the air discharge (22) is at most one third, preferably at most one quarter of the diameter of the air discharge (22).
9. External fan according to one of claims 1 to 8, characterised in that the fan housing (10) is formed in two parts and one part of the fan housing (10) receives the sound-absorbing member (3) and comprises the at least one air outlet opening (1031) in the fan housing (10).
10. External fan according to one of claims 1 to 9, characterised in that the sound-absorbing member (3) consists of foamed material.

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