Fan including at least one cover element

A fan for generating a gas flow for an air-conditioning system includes a housing having a pressure chamber and a suction chamber open to each other via a connecting opening. An impeller is arranged in the housing and includes an axial suction side arranged at the connecting opening and a radial pressure side arranged in the pressure chamber. An inlet and an outlet are disposed in the housing for communicating the gas flow. A fan cut-off is disposed on the housing between the pressure chamber and the outlet. At least one cover element is arranged in the inlet and axially spaced from the connecting opening to cover at least part of a flow cross-section of the inlet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 10 2014 226 298.4, filed Dec. 17, 2014, the contents of which are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention concerns a fan for generating a gas flow. The invention also concerns an air-conditioning system equipped with such a fan for conditioning an air flow.

BACKGROUND

A generic fan is known from DE 20 2005 012 569 U1. It comprises a housing in which a pressure chamber and a suction chamber are formed, which are open to each other via a connecting opening. Furthermore, an impeller is provided which has an axial suction side arranged in the connecting opening and a radial pressure side arranged in the pressure chamber. Furthermore, an inlet for supplying a gas flow to the suction chamber and an outlet for discharging the gas flow from the pressure chamber are formed in the housing. In the known fan, the impeller is also arranged eccentrically in the pressure chamber so that the pressure chamber is configured as a spiral outside the pressure side of the impeller. Furthermore, the pressure chamber transforms tangentially into the outlet. Finally, a fan tongue is formed on the housing between the pressure chamber and the outlet.

During operation of the fan, the impeller draws in gas from the suction chamber and delivers it to the pressure chamber. This creates a gas flow. This gas flow may lead to acoustic interactions between the impeller and the fan components exposed to the gas flow. In particular, undesirable noise may be generated. The design of the fan tongue allows a significant reduction in the noise development. It has however been found that even simple changes to the fan affect the guidance of the gas flow in the fan, and thus in particular influence the noise development. So even minor modifications to the fan may require a complex revision of the fan tongue in order to bring the noise development back to a tolerable level. There is therefore a need for additional sound reduction measures in order for example to simplify an adaptation of the fan to varying installation situations.

It is known from the above-mentioned DE 20 2005 012 569 U1 to create a surround for the connecting opening from a sound-absorbing material. Furthermore, a wall opposite the connecting opening may be made of sound-absorbing material. Also, a wall surrounding the pressure chamber in the peripheral direction may be made of a sound-absorbing material. The implementation of these sound-insulating measures is however comparatively complex. Also, these measures are only effective in the higher frequency range of the disruptive noise. In order to reduce the disruptive noise in the low frequency range too, it is still necessary to modify the fan tongue.

A further sound-damped fan is known for example from DE 41 15 171 C2, in which the pressure chamber is separated by perforated walls from absorption chambers in which a sound-deadening medium is arranged.

SUMMARY

The present invention deals with the problem of specifying an improved design for a fan of the type cited initially, or for a correspondingly equipped air-conditioning system, which is distinguished in particular by a reduced noise development while remaining simple and economic to produce.

This problem is achieved according to the invention by the subject of the independent claim(s). Advantageous embodiments are the subject of the dependent claims.

The present invention is therefore based on the general concept of providing at least one cover element in the inlet, i.e. axially spaced from the connecting opening, in particular at the transition to the suction chamber, which element covers a part of the flow cross-section of the inlet. In other words, the entire flow cross-section of the inlet available for the supply of the gas flow to the suction chamber is partially covered by at least one cover element, in order to increase locally the flow resistance in the flow cross-section. In this way the distribution of the flow into the suction chamber is modified or changed. Since only a comparatively small part of the flow cross-section is covered by the respective cover element, there is only a comparatively small increase in the total flow resistance in the inlet. Even if several cover elements are used in order to cover several parts of the flow cross-section, a substantial proportion of the flow cross-section always remains open, i.e. is not covered by such cover elements. The invention here uses the knowledge that by changing the flow distribution inside the flow cross-section of the inlet, it is possible to influence the acoustic interaction between the rotating impeller and the gas-guiding components of the fan. In particular, it has been found that the noise development of the fan can also be significantly reduced in this way. With regard to the above object, this means that for any modification of the fan which leads to increased noise development, the noise development can be reduced again by fitting at least one such cover element or by changing the position of such a cover element. Thus in a simple and economic manner, for every modified fan, a tolerable noise situation can be restored by use of a corresponding arrangement and/or number and/or configuration of cover elements. If the fan is equipped with a fan cut-off, with the measure described above, there may be no need for a complex adaptation of the fan cut-off.

According to an advantageous embodiment, a filter may be arranged in the inlet for filtering the gas flow. Suitably now the respective cover element is arranged in the inlet between the filter and the suction chamber. With regard to the gas flow downstream of the filter, the respective cover element has a particularly high influence on the gas flow.

The part of the flow cross-section covered by the respective cover element is comparatively small and for example is maximum 1/9. The part of the flow cross-section covered by the respective cover element may however be at least 1/20 or 1/16. Insofar as several cover elements are used, according to a preferred embodiment, the total covered part of the flow cross-section is maximum 50%, preferably maximum 25% of the flow cross-section of the inlet. Insofar as several cover elements are provided, these are suitably arranged spaced apart. The same or different cover elements may be used here.

According to another advantageous embodiment, the respective cover element is configured flat and smooth. In particular, in this way a thickness of the cover element, measured parallel to the flow direction of the gas flow in the inlet, is significantly smaller than a width and a height of the cover element measured transversely to the flow direction. The cover element may be rectangular, in particular square. Also round or irregular geometries are conceivable. According to an advantageous embodiment, the thickness of the cover element is maximum 10% of its height or width. In this way, the respective cover element can easily be integrated while retaining a compact form for the fan.

According to another advantageous embodiment, the respective cover element may lie in a cover plane which extends perpendicular to the rotation axis of the impeller. The rotation axis of the impeller defines the axial direction of the fan which runs parallel to the rotation axis. The radial direction of the fan and the peripheral direction of the fan also relate to the rotation axis. The arrangement of the respective cover element perpendicular to the rotation axis is particularly advantageous if the inlet transforms axially into the suction chamber. Here the inlet as a whole may in principle be oriented axially. It is also conceivable that the inlet transforms axially into the suction chamber substantially only at its outlet end, while at its inlet end it may in principle have any orientation relative to the rotation axis.

In another embodiment, it may be provided that the respective cover element is arranged only in an edge region of the inlet which surrounds, in the peripheral direction, a central region axially aligned with the connecting opening. It has been found that the influence on the gas flow, which also significantly affects the noise development, is achievable primarily in the edge region. Also, the remaining free central region guarantees a low as possible flow resistance at the transition between the inlet and the suction chamber.

In another embodiment, a carrier grid may be arranged in the inlet which, on a side facing the filter, carries the respective cover element. The arrangement of such a carrier grid in the inlet simplifies the attachment of the respective cover element. In particular, such a carrier grid may be structured for example such that, in principle, any suitable position may be set for the respective cover element, for example along the entire above-mentioned edge region. The respective cover element may be fixed to the carrier grid, for example by means of an adhesive connection or solder connection or weld connection. The variable positioning along the carrier grid is necessary for the respective cover element only for the variable formation of the fan, in order to adapt it acoustically to modified peripheral conditions. This adaptation is substantially simplified by the carrier grid.

According to an alternative embodiment which is preferred for series production, the respective cover element may be configured as an integral part of a carrier frame arranged on or in the inlet, such that the carrier frame with the respective cover element is produced from one piece, e.g. as an injection moulding of plastic. In particular, the carrier frame, like the carrier grid mentioned above, may be equipped with a grid structure. Also said carrier grid may form the carrier frame, so that in this case the respective cover element is integrated in the carrier grid. Furthermore, in principle it is conceivable that the respective cover element is formed during series production integrally on a housing part of the housing, whereby no separate carrier frame is required.

In a preferred embodiment, the cover element may have an annular, ellipsoid, rectangular or irregular form. The at least one annular cover element may here also be positioned in the inlet without a carrier frame or carrier grid, e.g. with carrier webs.

In an additional embodiment, at least two annular cover elements may be arranged concentrically or eccentrically to each other.

The above-mentioned optional filter may for example rest axially on the respective cover element, whereby the flow influence of the respective cover element is particularly efficient. In order however not to unnecessarily obstruct the filtration effect, according to another embodiment it may be provided that an axial distance is provided between the filter outlet side and the respective cover element.

According to another embodiment, at least one such cover element may have a closed surface so that the gas flow cannot pass through. For example, the cover element is a sheet of metal or plastic. The closed surface ensures a particularly intensive flow deflection by the respective cover element.

Additionally or alternatively, at least one such cover element may be perforated so that the gas flow can pass through in a choked fashion. For example, such a cover element may be formed from a perforated sheet of metal or plastic. Grid structures are also conceivable. The perforated cover element allows a less drastic intervention in the flow inside the inlet. Different perforations allow further modification of the intervention in the flow or the choke effect.

Suitably, the impeller may be arranged in the pressure chamber so that the pressure chamber is designed as a spiral outside the pressure side of the impeller. This means that the pressure chamber has a cross-section which increases radially in the peripheral direction, so that the pressure chamber cross-section increases in the peripheral direction from a starting region of the pressure chamber to an end region of the pressure chamber. Furthermore, it may be provided that the outlet transforms tangentially into the pressure chamber or the end region of the pressure chamber. In this way, the radial fan has a particularly high efficiency with regard to its delivery power for the gas flow. The fan cut-off arranged on the housing between the pressure chamber and the outlet defines the smallest radial gap between the housing and the impeller in the spiral pressure chamber, so that in the pressure chamber, it divides the outlet from the initial region of the pressure chamber.

According to another embodiment, at least one flow deflection element may be arranged in the suction chamber between the respective cover element and the connecting opening, and may protrude into the flow cross-section of the inlet and cause a deflection of the gas flow. By means of the flow deflection element, the flow through the housing can be significantly influenced, which may also contribute to the desired noise reduction in addition to the respective cover element.

The respective flow deflection element is preferably arranged axially spaced from the cover element. Furthermore, the respective flow deflection element may be arranged offset to the respective cover element in the peripheral direction.

It may advantageously be provided that the respective flow deflection element extends freestanding into the suction chamber and/or extends into the suction chamber so far that it radially overlaps the connecting opening. Insofar as several flow deflection elements are provided, these may be arranged distributed in the peripheral direction, wherein a symmetrical distribution is possible but not essential. Insofar as several flow deflection elements are used, these may be identical or similar. Alternatively, the flow deflection elements may also be different.

According to another embodiment, a filter may be arranged in the inlet for filtering the gas flow, wherein the respective cover element is arranged in the inlet between the filter and the suction chamber. Filtration of the aspirated gas flow also influences the flow through the fan, and consequently also has an effect on the noise development. Depending on the filter used, therefore, the position and/or number and/or geometry and/or configuration of the respective cover elements may vary.

An air-conditioning system according to the invention for conditioning an air flow, which is preferably provided for a motor vehicle, comprises at least one fan of the type described above for driving the air flow. Furthermore, such an air-conditioning system may comprise at least one heating device for heating the air flow and/or at least one cooling device for cooling the air flow.

Further important features and benefits of the invention arise from the subclaims, the drawings and the associated description of the figures with reference to the drawings.

It is understood that the features cited above and to be explained further below may be used not only in the combination given, but in any combination or alone, without leaving the scope of the present invention.

Preferred exemplary embodiments of the invention are depicted in the drawings and explained in more detail in the description below, wherein the same reference numerals refer to the same or similar or functionally equivalent components.

DETAILED DESCRIPTION

According toFIG. 1, an air-conditioning system1, which serves to condition an air flow2and is preferably used in a motor vehicle, comprises at least one fan3for driving the air flow2, which may also generally be known as a gas flow2. The air-conditioning system1also comprises at least one heating device (not shown here), and/or at least one cooling device (not shown here), for heating and/or cooling the air flow2.

The fan3comprises a housing4which contains a pressure chamber5and a suction chamber6. Between the pressure chamber5and the suction chamber6, a connecting opening7is formed in the housing4which connects the two chambers5,6fluidically together. In particular, the pressure chamber5and the suction chamber6are open to each other in the connecting opening7. In this example, the connecting opening7has a nozzle contour8which converges in a flow direction oriented away from the suction chamber6towards the pressure chamber5. This nozzle contour8has a greater cross-section at the inlet to the connecting opening7than at the outlet from the connecting opening7. The two cross-sections are shown as two concentric circles inFIGS. 3 to 8.

An impeller9is also arranged in the housing4and configured as a radial impeller. The impeller9is connected via a drive shaft10to a drive motor11, which drives the impeller9in operation of the fan3so that it rotates about a rotation axis12. The rotation axis12defines an axial direction13of the fan3which runs parallel to the rotation axis12. A peripheral direction14indicated by a double arrow inFIG. 2, and a radial direction (not shown in detail) relate to this axial direction13. The impeller9has an axial suction side15which is arranged at the connecting opening7. In principle, the suction side15may also protrude axially into the connecting opening7. Furthermore, the impeller9has a radial pressure side16located in the pressure chamber5. In operation of the fan3, the impeller9at its suction side15draws in air from the suction chamber6so that the air flow2enters the impeller9through the suction side15. At the pressure side16, the air flow2is expelled from the impeller9and delivered or pressed into the pressure chamber5.

An inlet17is also formed in the housing4, through which the gas flow2reaches the suction chamber6. Furthermore, the housing4according toFIG. 2has an outlet18through which the gas flow2can escape from the pressure chamber5. As also shown inFIG. 2, the impeller9is arranged in the pressure chamber5so that outside the pressure side16of the impeller9, the pressure chamber5has a spiral contour in cross-section perpendicular to the rotation axis12. In particular, the impeller9is arranged eccentrically to this in the pressure chamber5. Furthermore, the outlet18is arranged so that the pressure chamber5transforms tangentially into the outlet18. Also, a fan cut-off19is formed on the housing4, namely at a transition between the pressure chamber5and the outlet18. A rotation direction20of the impeller9is suitably oriented so that at its outer periphery, i.e. on its pressure side16, in the region of the outlet18, the impeller9moves in the direction towards the fan cut-off19. In this rotation direction20, a radial distance21or radial gap21between the pressure side16of the impeller9and a wall22radially delimiting the pressure chamber5also increases. In the pressure chamber5, the fan cut-off19separates the starting region of the pressure chamber5, at which the radial gap21is relatively small, from an end region of the pressure chamber5, at which the radial gap21is relatively large and which transforms into the outlet18. To this extent, in the housing4the fan cut-off19also separates the outlet18from the starting region of the pressure chamber5.

According toFIG. 1, suitably a filter23is arranged in the inlet17, through which the air flow2passes and is filtered. Furthermore, at least one cover element24is arranged in the inlet17between the filter23and the suction chamber6, such that it at least partially covers a flow cross-section of the inlet17designated25inFIGS. 3 to 8. The respective cover element24thus causes a local blockade or choking of the flow section25in a carefully selected part of the flow cross-section25. According toFIGS. 1 and 4 to 8, the respective cover element24is formed flat and smooth. It lies in a cover plane37running perpendicular to the rotation axis12.

The section plane III-III of the cross-section shown inFIG. 3, relative to the flow direction of the air flow2, is located downstream of the filter23and downstream of the respective cover element24, so thatFIG. 3forms a top view onto the housing4in the region of the suction chamber4, and the suction side15of the impeller9can be seen through the connecting opening7. In contrast, inFIGS. 4 to 8the respective section plane IV-IV is positioned upstream of the respective cover element24, so that there is also a view of the inlet17and the flow cross-section25can be seen. Similarly, the connecting opening7and the suction side15of the impeller9can be seen. The section plane IV-IV as indicated inFIG. 1may be positioned precisely at the border between the filter23and the cover element24. It is also conceivable that the filter element23has been omitted inFIGS. 4 to 8, in order to allow the axial view shown.

In the examples ofFIGS. 4 to 6 and 8, two cover elements24are provided. In the example ofFIG. 7however, only a single cover element24is provided. It is also conceivable that more than two cover elements24may be provided. In the examples ofFIGS. 4 to 6 and 8, the cover elements24are arranged exclusively in an end region26of the inlet17which extends closed in the peripheral direction14. The edge region26thus surrounds a central region27of the inlet17which aligns axially with the connecting opening7. Thus the connecting opening7lies largely inside the central region27. In other words, the cover elements24do not extend as far as the central region27and thus in particular cause no covering, or at least no substantial covering, in any case only an edge-side covering, of the connecting opening7in the axial projection shown inFIGS. 4 to 6 and 8.

For easier positioning of the cover elements24in the flow cross-section25, according toFIGS. 1 and 4 to 6 and 8, a carrier grid28may be provided in the inlet17which, on a side facing the filter23, carries the respective cover element24. This side is facing the observer inFIGS. 4 to 6 and 8. The carrier grid28comprises a grid frame29which peripherally surrounds the flow cross-section25. Furthermore, the carrier grid28comprises a plurality of grid rods30which extend inside the grid frame29and form additional support points for the cover elements24inside the grid frame29. On the edge side, the cover elements24may lie on the grid frame29. To fix the cover elements24to the grid frame29, suitable fixing methods may be used, such as for example gluing, soldering and welding. Alternatively, it is advantageous for series production of the fan3if the respective cover element24is not produced separately from the grid frame28, but is integrated therein. With such an integral construction, instead of such a grid frame29, a more simply structured carrier frame41may be used which in principle does not have such a grid structure. Preferably, the cover element24or cover elements24are produced integrally with the carrier frame41or carrier grid28, e.g. as a one-piece or single-material injection moulding made of plastic.

In the embodiment shown inFIG. 1,FIGS. 4 to 6, andFIG. 8, the carrier grid28extends in a grid plane31which in turn is oriented perpendicular to the rotation axis12. The flat cover elements24lying thereon extend parallel to this. The grid frame29and grid rods30, and also the carrier frame41, are designed comparatively narrow or thin so they fulfil their supporting or retaining function for the cover elements24but have scarcely any effect on the flow cross-section25.

In the embodiment shown inFIG. 4, the two cover elements24are each provided with a perforation32, whereby the gas flow2or air flow2can flow through the cover elements24, albeit choked in comparison with the remaining free region of the flow cross-section25which is not covered by a cover element24. Purely as an example, different perforations32are shown inFIG. 4, whereby the choke effect of the respective cover plate24may be adapted individually.

In the embodiment shown inFIG. 5, the two cover elements24each have a closed surface so the air flow2cannot pass through. This achieves a particularly intensive deflection of the air flow2.

Also, according toFIG. 6, an embodiment is conceivable in which at least one closed cover element24and also at least one perforated cover element24are used.

As also shown inFIGS. 4 to 6, different positions are conceivable for the cover elements24, which may be set depending on the respective application. The respective application arises from the different conditions of use and/or peripheral conditions of the respective fan3. For example, inFIG. 1an axial flow of the air flow2to the suction chamber6is indicated. In another embodiment, this flow may be angled relative to the axial direction. In particular, the air flow2may also enter the suction chamber6radially. The positioning of the at least one cover element24depends for example on this spatial orientation of the flow; also other parameters, such as for example the available flow cross-section and its geometry, may lead to a changed flow within the fan3, wherein an accompanying change in noise development can be compensated by a correspondingly adapted positioning and/or arrangement of the at least one cover element24.

In the embodiment shown inFIG. 1, the housing4has a step33which serves as an axial support for the carrier grid28or the carrier frame41where applicable. Furthermore, here the filter23is positioned so that its outlet side34makes contact with the respective cover element24. Suitably however, in another embodiment, a position for the filter23may be proposed in which there is an axial distance between the outlet side34of the filter23and a flow contact side35of the cover elements24facing the filter23. To fix the filter23in the housing4, a cover plate36is here also provided.

According toFIG. 7, an annular cover element24may also be used, which is arranged concentrically or coaxially to the rotation axis12of the impeller9. Also, several annular cover elements24may be provided which are arranged concentrically to each other. In the example, the annular cover element24is configured as a circular ring so it has an inner radius38and an outer radius40. The dimensioning of the cover element24is selected here such that it covers the connecting opening7on the edge side. In particular, an opening radius39of the also circular connecting opening7is greater than the inner radius38and smaller than the outer radius40. The annular cover element24is supported or held on the housing4, and positioned in the desired position, by means of a plurality of carrier webs43. The carrier webs43may be provided either separately from the cover element24and attached suitably thereto, or may be formed integrally thereon. Also, a carrier frame41may again be provided, on which the carrier webs43are formed.

According toFIG. 8, in addition to the cover elements24, at least one flow deflection element42may be provided which is arranged in the suction chamber6between the connecting opening7and the cover elements24. In this example, several flow deflection elements42are shown which are arranged evenly distributed in the peripheral direction14and which are here also configured identically. The flow deflection elements42extend at the side, freestanding, into the suction chamber6so far that their freestanding end44lies inside the connecting opening7in the axial projection shown. This gives a radial overlap of the connecting opening7by the flow deflection elements42. The flow deflection elements42may be formed as aerodynamically curved vanes, whereby they achieve a particularly efficient flow deflection. In a particularly advantageous embodiment, the at least one flow deflection element42is configured and/or arranged to act on the air flow2with a twist, in particular in the rotation direction20of the impeller9, in order thus to reduce the flow resistance of the fan3. In the view ofFIG. 8, the flow deflection elements42are arranged behind the carrier grid28or behind carrier frame41and axially spaced therefrom. Furthermore, the flow deflection elements42are arranged axially spaced from the connecting opening7in the suction chamber6. Alternatively, the flow deflection elements42may also extend as far as the connecting opening7or protrude into the connecting opening7.