Patent Application
20230032483
The present disclosure relates to a housing for a fan, in an embodiment for an axial or diagonal fan, the fan including an impeller and at least one flow-through region. The disclosure also relates to a fan with such a housing.
Fans which include a drive, an impeller and a housing, in particular axial or diagonal fans, are well known from practice. In addition, it is known to provide such fans with guide blades, diffusers, multi-diffusers and combinations thereof in order to influence the flow. In particular, high static efficiencies are to be achieved.
Although the disclosure relates very generally to a housing for a ventilator and a ventilator with such a housing, this disclosure relates in particular to a ventilator and a housing provided therein, as shown in terms of the basic structure in
A return flow through the radial gap between the impeller and the housing reduces in particular the static efficiency and causes a not inconsiderable amount of noise. The inner guide blades 3 and the outer guide blades 3a are ,in an embodiment, load-bearing guide blades, that is to say they have, among other things, the function of ensuring the supporting connection of the motor to the housing.
The present disclosure is based on the object of designing and developing the housing for such a fan, in an embodiment for an axial or diagonal fan, in such a way that the harmful effects of a so-called head gap leakage flow are at least reduced, if not largely eliminated. The effectiveness of downstream diffusers should be improved, and blockage effects in the form of a backflow region should be reduced. The problems occurring in the state of the art are to be solved with simple design means that distinguish both the housing according to the disclosure and the fan according to the disclosure from competitive products.
The object relating to the housing is achieved according to the disclosure by the features of claim 1. Accordingly, the generic housing is characterized in that multiple individual, free-standing guide elements are provided immediately downstream of the impeller or the blades of the impeller in an outer region of the housing. The object relating to the fan is achieved by the features of claim 18.
The features according to the disclosure appear astonishingly simple, according to which individual obstacles are provided downstream of the impeller and thus downstream of the blades of the impeller where head gap leakage flows or a backflow region can occur, specifically in an outer region of the housing, regardless of which concrete structural/constructive features the housing and the fan have. The obstacles are designed as individual free-standing guide elements, so they do not belong to a unitary or supporting guide device. They are to be understood as individual structural elements which are formed directly on or in the inner wall of the housing.
In concrete terms, it is conceivable that the individual free-standing guide elements are formed by a combination of depressions and elevations in the inner wall of the housing in order to achieve special flow effects. This measure enables an effective profiling of the inner wall of the housing with the help of free-standing guide elements.
In an embodiment the individual free-standing guide elements, viewed individually, are integrated into the inner wall of the housing. In this case, the housing can be produced using injection molding technology or cast metal with integral, individual, free-standing guide elements.
Alternatively, the individual free-standing guide elements, regardless of the material and the manufacture of the housing, may be formed of metal or plastic and are attached to the inner wall of the housing, for example by means of adhesives or welding.
In order to achieve a sufficiently good fluid-dynamic effect, a sufficiently large number of free-standing guide elements is provided, depending on the size of the housing, in the range between 20 and 100 pieces.
The individual free-standing guide elements can be arranged equidistantly from one another on the inner wall of the housing over the circumference of the inner wall of the housing. An equal distribution of the free-standing guide elements should bring about an effective stabilization of the otherwise swirling flow and/or redirect this flow more in the direction of flow. As a result, turbulence can also be removed more quickly from the impeller.
In an embodiment the position of the individual free-standing guide elements with supporting guide blades of a guide device alternates in terms of their position, in the circumferential direction, in such a way that between two supporting guide blades of the guide device, several individual free-standing guide elements, for example four to twelve free-standing guide elements, protrude radially, possibly obliquely at a predetermined angle from the housing wall. In any case, it is of importance that the individual free-standing guide elements are attached essentially directly downstream of the impeller and there counteract a backflow against the actual conveying direction.
The individual free-standing guide elements can be of identical design and protrude from the inner wall of the housing at an identical angle. It is also conceivable that the individual free-standing guide elements are aligned alternately with alternating angles and accordingly protrude from the inner wall of the housing in different directions.
Based on a particular housing, which has an essentially circular cross-section with an essentially cylindrical, possibly ring-like flow region, in which the impeller is arranged, it is advantageous if the individual free-standing guide elements are formed at the end of the cylindrical region or at the beginning of a subsequent, widening diffuser region or in the transition between the two regions. The immediate proximity to the impeller is of importance. The free-standing guide elements counteract any flow separations on the inner wall of the housing downstream of the impeller, resulting in a low-noise fan with high efficiency, namely as a result of flow stabilization by the individual free-standing guide elements on the inner wall of the housing. In addition, the provision of the individual free-standing guide elements improves the effectiveness of a diffuser which is integrated in the housing and can be connected to the aforementioned cylindrical region of the housing wall.
In concrete terms, it is advantageous if the individual free-standing guide elements extend radially away from the inner wall of the housing only slightly less or slightly more than an annular gap formed between the blades of the impeller and the inner wall of the housing. The ratio of the height of the individual free-standing guide element to the annular gap width can be in the range from 0.8 to 3.0. The axial distance of the individual free-standing guide element to the blade of the impeller is, in an embodiment, less than eight times the gap width on the housing wall.
The mere provision of the individual free-standing guide elements provides, in accordance with the above statements, an enormous contribution to stabilizing the otherwise swirling flow in the region downstream of the radial gap between the impeller and the housing. A further optimization is possible through the specific shape of the individual free-standing guiding elements. The individual free-standing guide elements can have a rather rounded leading edge and a rather thin, “pointed” tapered trailing edge.
Basically, it is advantageous if the individual free-standing guide elements have a profiled contour that corresponds approximately to the contour of an airfoil or an impeller blade. Such a measure also promotes the effect and thus stabilization of the flow.
Furthermore, it is advantageous if adjacent individual free-standing guide elements have a certain inclination, namely are aligned at a certain angle transversely to the longitudinal axis. It is in turn advantageous if free-standing guide elements adjacent in the circumferential direction, viewed in projection onto a plane perpendicular to the fan axis, do not overlap in the circumferential direction, or at least have a small distance from one another. This facilitates demolding from a casting tool, for example an injection molding tool.
At the free end, the individual free-standing guide elements can be designed differently, depending on the specific installation situation and sizing. The individual free-standing guide elements can have a blunt, angular, rounded, beveled or even free angled end, which has a significant influence on the air flow. Coordination with the overall structural situation is an advantage.
Furthermore, an underlying object in relation to the claimed fan, in an embodiment an axial or diagonal fan, is achieved by using a housing with features according to one of claims 1 to 17. Corresponding statements can be omitted by referencing the statements relating to the housing.
There are then various possibilities for advantageously designing and refining the teaching of the present disclosure. For this purpose, reference should be made on the one hand to the claims subordinate to claim 1 and on the other hand to the following explanation of exemplary embodiments of a fan according to the disclosure with reference to the drawings. In connection with the explanation of the exemplary embodiments of the disclosure with reference to drawings, embodiments and refinements of the teachings are also explained in general.
The outer flow-through region 6 has a small number of outer guide blades 3a, which in an embodiment provide the static connection of the outer ring 5 to the housing 2. Due to the small number of outer guide blades 3a in this region, little additional noise is caused in this region as a result of the interaction of the flow emerging from the impeller with the outer guide blades 3a. A large number of free-standing guide elements 16 are attached to the inner wall of the housing 2, in the exemplary embodiment 54 pieces, in another embodiment 30-100 pieces. They are ,in an embodiment, integrally connected to the housing 2, for example by plastic injection molding. A metal casting is also conceivable.
It is also conceivable that free-standing guide elements made of plastic or metal are glued, welded or the like into a housing. The free-standing guide elements 16 are attached in a region on the housing wall on the inflow side of the guide device 15, but can also overlap with it, as seen in the axial direction. It is of importance that the free-standing guide elements 16 are mounted essentially directly downstream of the impeller (not shown here) at a short distance, which is, in an embodiment, no greater than the axial extent of the corresponding free-standing guide element 16. They have a free end facing away from the wall of the housing 2 and protrude from the wall of the housing 2 at only a relatively small height. The free-standing guide elements 16 ensure stabilization of the, depending on the operating point, strongly swirling flow in the region downstream of the radial gap between impeller and housing 2 (see also
Overall, a fan is obtained, which is quiet and has a high degree of efficiency, namely as a result of the flow stabilization or the flow acceleration in the direction of flow through the free-standing guide elements 16 on the wall of the housing 2, which in particular can improve the effectiveness of the outer diffuser 10 integrated in the housing 2.
There is a provision 18 for fastening a motor 34 in the region of the receiving region 8 within the hub ring 4. The motor 34, shown schematically, is attached thereto. The guide device 15 provides the connection of the motor 34 and, indirectly via this, also of the impeller 19 to the housing 2. The motor 34 is connected to the guide device 15 on the stator side. On the rotor side, the motor 34 is connected to the impeller 19 by a fastening provision 30. The impeller 19 consists essentially of a hub ring 21 and blades 22 attached thereto. The hub ring 21 is , in an embodiment, designed in such a way that the stagger angles of the blades 22 can be adjusted, depending on the needs of the ventilation application in which the fan 1 is used.
There are basically two different support concepts for the motor 34 with the impeller 19.
On the one hand, as in the exemplary embodiment shown, a supporting guide device 15 can be provided. That is, a guide device 15 having an aerodynamic function connects the motor 34 to the housing 2 and supports it. On the other hand, the motor 34 can be attached to the housing 2 with a purely mechanical connection, for example consisting of rods, wire, flat material or the like. In such a case, a guide device 15 may or may not be provided.
In other exemplary embodiments, a guide device 15 can also be designed without an outer ring 5 and/or with only one type of guide blades, which are load-bearing.
It can be seen in
In the exemplary embodiment, both the wall of the housing 2 and the hub ring 4 have a conical shape towards the outflow end. An outer diffuser 10 is thus integrated in the housing 2. Both the inner flow-through region 7 and the outer flow-through region 6 are designed towards their outflow end as diffusers with a widening flow cross section. This is very advantageous for the static efficiency, especially with axial fans. The outer ring 5 of the guide device 15 is also slightly conical in the embodiment, slightly widening radially in the direction of flow.
The inner flow-guiding wall of the housing 2 essentially has the contour of an inlet nozzle 9, which is followed by a cylindrical region 11, followed by the radially opening diffuser region 10. The impeller runs at least for the most part in the region 29 in the flow direction at the level of the cylindrical flow-through region 11. The free-standing guide elements 16 can be arranged at the end of the cylindrical region 11 or at the beginning of the diffuser region 10 or in the transition region between the two regions. In any case, the free-standing guide elements 16 are attached downstream of the impeller 19 or its blades 22 (see
On a housing 2 and/or a guide device 15, fastening provisions, for example fastening flanges, can be integrated or attached on both the inflow and outflow side, which provisions are used to fasten the fan to a higher-level system, for example an air conditioning system.
These losses can be significantly reduced by the free-standing guide elements 16, which run very close to the blades 22 downstream of the same. These free-standing guide elements 16 convert part of the velocity components in the circumferential direction into those in the axial direction, namely they direct the local flow more in the axial direction.
This causes a reduction in the return flow region in the region of the radial gap with width d 12 and thus a reduction in the losses and the generation of noise as well as the (partial) blockage of a subsequent diffuser delimited to the outside by an outer diffuser 10.
The free-standing guide elements 16 run radially only very locally in the region of the radial gap of the impeller with the width d 12 or only by a small factor beyond this. In practice, the free-standing guide elements 16 have the height h 23, measured from the wall of the housing 2. The ratio of h 23 to d 12 is, in an embodiment, in the range of 0.8-3. The axial distance between the free-standing guide elements 16 and the blade 22 on the wall of the housing 2 is, in an embodiment, less than 8 times the gap width d 12.
In the exemplary embodiment, the free-standing guide elements 16 run in the region of the outer diffuser 10. In other embodiments, they can also run in the cylindrical region 11. If, as in the exemplary embodiment, they run in the region of the outer diffuser 10, demolding of a one-piece cast housing 2 is made more difficult. In an embodiment, special demolding regions (not shown) are incorporated, which allow demolding with an open-close tool with demolding directions parallel to the axis without additional slides.
According to the disclosure, the free-standing guide elements 16 deflect the strongly swirling flow in the region of the wall of the housing 2 more in the axial direction. Other geometric solutions are also conceivable in other embodiments, in which the free-standing guide elements are, for example, more integrated into the contour of the housing, for example in the form of depressions, elevations or the like. It is of importance that this flow influencing takes place only near the housing wall and in the immediate vicinity of the impeller blades, where an interaction with a leakage flow of a radial gap between the impeller blades and the housing takes place.
The free-standing guide elements 16 have an inflow edge 13, which is ,in an embodiment, at least approximately rounded, and an outlet edge 14, which is thin compared to the rest of the profile. Viewed in cross section, the free-standing guide elements 16 have approximately the profiled contour of an airfoil. In other embodiments, other cross-sectional contours are also possible, for example a thin contour with an essentially constant thickness. The free-standing guide elements 16 have a chord length s 31 and an axial extent I 32. In terms of values, I 32 is small, for example 0.2%-5% of the impeller diameter or 10%-60% of the axial extension of an impeller blade. The chord length s 31 is greater than I 32 by a factor of about 1.2-2. Viewed in the circumferential direction, adjacent free-standing guide elements 16 do not overlap, in order to enable easier demolding of the housing 2 from a casting tool. The inflow angle α 27 is assigned to the inflow edge 13. This is the local angle there between the chord 37 or its tangential extension and a line parallel to the axis 26. The outflow angle β 28 is assigned to the outflow edge 14. This is the local angle there between the skeleton line 37 or its tangential extension and a line parallel to the axis 26. The angle β 28 is smaller than the angle α 27, in an embodiment, by at least 20°. As a result, the swirling flow is more likely to be deflected in the axial direction. In this case the free-standing guide elements 16 have a front end 24.
To avoid repetition with regard to further embodiments of the fan according to the disclosure with the housing according to the disclosure, in order to avoid repetitions, reference is made to the general part of the description and to the appended claims.
Finally, it should be expressly noted that the above-described exemplary embodiments of the fan according to the disclosure and of the housing according to the disclosure are used solely to explain the claimed teaching, but do not restrict it to the exemplary embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 200 447.1 | Jan 2020 | DE | national |
This application is a national stage entry application under 35 U.S.C. 371 of PCT Patent Application No. PCT/DE2020/200108, filed on 4 Dec. 2020, which claims priority to German Patent Application No. 10 2020 200 447.1, filed on 15 Jan. 2020, the entire contents of each of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2020/200108 | 12/4/2020 | WO |
