Outlet guiding device for fan and fan with outlet guiding device

Abstract

The invention relates to an outlet guide unit for a fan having at least one impeller comprising impeller blades, comprising an outer housing and at least one outlet guide wheel with inner guide blades, said outlet guide wheel having an intermediate ring, the intermediate ring is preferably held concentrically in / on the housing by means of at least three diagonal bracing blades distributed over the circumference. The invention also relates to a fan with a corresponding outlet flow guide device.

Description

Technical Field

[0001] The invention relates to an outlet guide device for a fan, the fan having at least one impeller with impeller blades, the outlet guide device having an outer housing and at least one outlet guide wheel, the outlet guide wheel having inner guide blades, wherein the outlet guide wheel has an intermediate ring, which is preferably held concentrically in / on the housing by means of at least three circumferentially distributed strut blades. The invention also relates to a fan having a corresponding outlet guide device. Background Art

[0002] Fans with outlet guide devices are already sufficiently known from practice. For this purpose, reference may be made only by way of example to WO 2020 / 015792 A1. Such fans with outlet guide devices, in particular internal outlet guide devices, are problematic in practice. The outlet guide device extends only through the area of ​​the flow surface from the axis. Usually, it combines higher static efficiency with lower sound power values, because there are no outlet guide blades in the external area that is important for this, which would generate particularly strong rotational noise. Nevertheless, the motor-impeller and the internal outlet guide wheel of the fan must always be maintained. The maintenance or suspension of the outlet guide device is usually complicated, reduces efficiency and is conducive to sound generation. In addition, with respect to the fixing devices implemented so far, mechanical stresses and deformations occur during the operation and transportation of the fan, which frequently lead to damage. Summary of the invention

[0003] The object of the invention is to eliminate at least to the greatest extent the defects present in the prior art. On the one hand, damage to the outlet guide wheel and the fan due to mechanical stress should be avoided. On the other hand, sound generation and efficiency losses should be minimized. In addition, the outlet guide device according to the invention should be distinguished from competing products. The same applies to the fan according to the invention.

[0004] The aforementioned object is achieved with respect to the outlet guide device by the features of claim 1. With respect to the fan according to the invention, the object is achieved with respect to the features of the parallel claim 14, according to which the fan according to the invention comprises the outlet guide device according to the invention. Finally, the outlet guide device and its structural features are concerned.

[0005] The outlet guide device according to the present invention is used to be constructed in a fan, which may be an axial flow, radial flow or mixed flow fan. The fan includes at least one impeller having a plurality of impeller blades. The basic structure of such a fan can be referred to WO 2020 / 015792 A1 as an example only. Here, such a fan is not described again by citing a known fan.

[0006] According to the invention, the outlet guide unit comprises an outer housing, in which an outlet guide wheel with inner guide vanes is arranged. The outlet guide wheel has an intermediate ring, on which the inner guide vanes terminate. More precisely, the inner guide vanes extend between a hub ring or an inner ring of the outlet guide device and the intermediate ring, so that the guide vanes are arranged there in a fixed position.

[0007] It is now particularly important that the intermediate ring of the outlet guide wheel is preferably held concentrically in or on the housing by means of at least three sprag blades distributed over the circumference. The sprag blades have holding or fixing properties and act between the intermediate ring and the inner side of the outer housing. In addition, these sprag blades are designed in the sense of blades and are specifically designed to be optimized with respect to the airflow and at the same time optimized for strength.

[0008] Advantageous developments of the stated teaching result from the following.

[0009] The various components of the outlet guide device can be integrally cast, in particular guide vanes, which are connected to the inner surface of the housing via an intermediate ring through sprag vanes and thus to the outer housing contour. The sprag vanes have load-bearing performance and a flow-optimized design.

[0010] Specifically, the sprag blades are significantly inclined relative to the blade trailing edge of the impeller or an imaginary radial ray. These sprag blades can be arranged at a greater distance from the impeller blade trailing edge. This distance, for example, can be greater than the axial extension of the sprag blade when viewed in the axial direction.

[0011] Furthermore, the number of the sprag blades is relatively small, preferably smaller than the number of the inner guide blades.

[0012] It is important that the sprag blades have a smaller fluid dynamics effective area than the inner outlet guide vanes. The sprag blades are designed to be thicker in order to ensure the rigidity required during transportation of the corresponding fan and during operation.

[0013] In a cross-sectional view, for example in a cross-section of a cylindrical circumference coaxial with the fan axis, the sprag blades are inclined and oriented in such a way that they produce as little resistance as possible to the swirl flowing out of the impeller of the fan. It is particularly advantageous if, in terms of geometry, no or at most a small flow deflection occurs at each sprag blade.

[0014] It is also advantageous if the sprag blades are fastened to the outer housing as far away from the diffuser inlet as possible or are formed in the region of the diffuser. The resulting large undercut region is advantageously not filled with a demoulding wedge, but is demoulded by means of a special demoulding strategy using a slide. In this regard, possible efficiency losses and noise generation due to demoulding wedges integrated in the component are avoided in a simple injection molding production technology.

[0015] In the outlet guide device according to the invention, the sprag blades extending between the intermediate ring and the outer housing are inclined relatively significantly relative to the blade edges of the impeller or to an imaginary radial ray, viewed in a direction parallel to the fan axis, without causing a flow deflection. Due to the large distance between the sprag blades and the trailing edge of the impeller blade, possible sound generation at the sprag blades is avoided or minimized.

[0016] It is also conceivable that the outlet guide device is equipped with a cooling structure, which is preferably assigned to the outlet guide wheel. More precisely, the cooling structure is integrated in one piece in the outlet guide wheel. The cooling structure is used to provide a cooling flow due to the operation of the fan by a pressure difference. In this way, heat is removed from the electric motor. Heat removal means cooling.

[0017] The outlet guide device according to the invention is thus advantageous in terms of stability / strength and in terms of reduced efficiency losses and reduced sound generation. These advantages are achieved, as the foregoing description shows, by surprisingly simple structural design measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] There are many possibilities for beneficial design and improvement of the teaching of the present invention. For this purpose, reference may be made to the dependent claims of claim 1 on the one hand and to the explanation of preferred embodiments of the outlet air guide device and the corresponding fan according to the present invention in the following text by means of the drawings on the other hand. In conjunction with the explanation of the preferred embodiments of the present invention by means of the drawings, generally preferred design solutions and improvement solutions of the teaching are also explained. In the drawings:

[0019] Figure 1 A perspective view showing a fan having a load-bearing outlet air guide unit according to the present invention viewed from the outflow side, wherein the outlet air guide unit has a housing, an outlet air guide device and a diagonal support blade;

[0020] Figure 2a Shown from the outflow side Figure 1 An axial plan view of a fan having a load-bearing outlet guide unit is shown;

[0021] Figure 2b Show Figure 2aDetailed view in the area of ​​a sprag blade, wherein the extension of the sprag blade, the extension of the fan blade and radial rays are each shown as characteristic curves in a projection onto the viewing plane;

[0022] Figure 3 Shown from the upstream side Figure 1 and 2a An axial plan view of a fan having a load-bearing outlet guide unit is shown;

[0023] Figure 4a Show Figure 1 , 2a 3 and 3 show a side view of a fan with a load-bearing outlet guide unit and a section on a plane passing through the axis, wherein schematically marked dimensions are shown in the region of the inlet nozzle;

[0024] Figure 4b Show Figure 4a Detailed view in the area of ​​a sprag blade, with three characteristic parameters indicated schematically;

[0025] Figure 4c Show Figure 4a Detailed view in the region of a sprag blade, wherein the undercut region is schematically indicated by hatching with respect to demoulding from the injection mold in a direction parallel to the fan axis;

[0026] Figure 5a Show Figure 1 , 2a , 3 and 4a are side views of a fan with a load-bearing outlet guide unit and a cross-section on a plane parallel to the axis and the plane of the view, in which the diagonal blades can be seen;

[0027] Figure 5b Show Figure 5a Detailed view in the area of ​​the visible strut blade, with four characteristic parameters schematically shown;

[0028] Figure 6a A side view and a section on a plane passing through the axis of another embodiment of a carrier-type outlet guide unit are shown, in which a demoulding wedge is provided in the region of the diffuser for easier demoulding;

[0029] Figure 6b Show Figure 6a Detailed view of the sprag blade in the area with the demoulding wedge;

[0030] Figure 7a An axial plane top view of a fan having a load-bearing outlet guide unit of another embodiment is shown as viewed from the outflow side, wherein a flow disturbance curve in the impeller wake slightly downstream of the trailing edge of the impeller blade on a plane perpendicular to the axis obtained by means of flow simulation is shown;

[0031] Figure 7b Shown with Figure 7a For the fan in the same flow conditions, the flow disturbance is now in a plane perpendicular to the fan axis, however at a greater distance from the impeller blade trailing edge and very upstream of the sprag blade leading edge. DETAILED DESCRIPTION

[0032] Figure 1 A perspective view of an axial fan 57 from the outflow side is shown, which has an embodiment of a load-bearing outlet guide device 1. The outlet guide device 1 comprises in particular a housing 2, an intermediate ring 5, a hub ring 4, inner guide blades 11 extending between the hub ring 4 and the intermediate ring 5, and strut blades 3, 3a extending between the intermediate ring 5 and the housing 2 or its diffuser region 10.

[0033] The outlet guide device 1 is advantageously manufactured in one piece by an injection molding method, advantageously a plastic injection molding method. The housing 2 defines the outer boundary of the fan flow channel extending in the housing 2. The housing 2 comprises a plurality of regions: in the throughflow direction, first an inlet nozzle 9, then an advantageously cylindrical region 29 and a diffuser region 10, in which the impeller 19 and its blades 22 are arranged, and on which the sprag blades 3, 3a are fastened.

[0034] Inside the housing 2, downstream of the impeller 19, an internal outlet guide device is provided, which in particular includes fluid-mechanically effective internal outlet guide vanes 11, which extend between the hub ring 4 and the intermediate ring 5. Due to the fluid-mechanical effect produced by the cooperation between the internal outlet guide vanes 11, the intermediate ring 5 and the hub ring 4, the fan 57 has a particularly high efficiency and air volume power. On the hub ring 4, radially inside thereof, a motor 34 with a stator 36 is fastened in the receiving area 8, so that the internal outlet guide vanes 11 and the intermediate ring 5 also have the function of supporting the motor 36 and the impeller 19.

[0035] In order to hold the motor 34 together with the impeller 19 and the built-in outlet guide device on the outer housing 2, external bracing blades 3, 3a are provided. These external bracing blades have only a secondary fluid dynamics function, and are mainly used to fasten the built-in outlet guide device and thus the motor 34 and the impeller 19 to the outer housing 2. These external bracing blades are of low-noise design, and due to their existence, the fan 57 does not generate or only generates a slight amount of additional noise during operation. In summary, inside the housing 2, in the axial region of the diffuser 10, viewed along the span direction (viewed from the hub 4 to the diffuser 10), two different flow channel areas are constructed: an external flow channel area 6 located between the intermediate ring 5 and the diffuser wall 10 of the housing 2, and an internal flow channel area 7 located between the hub ring 4 and the intermediate ring 5. The internal flow channel area 7 has load-bearing internal guide elements 11, which have fluid dynamics functions and, for example, reduce air flow vortices, avoid or reduce hub backflow, and these load-bearing internal guide elements generate only weak noise due to their radial inner position.

[0036] The external flow channel area 6 is provided with similarly load-bearing diagonal blades 3, 3a, in this embodiment, there are 6 in total, advantageously 4 to 8, which are distributed on the circumference, and these diagonal blades are optimized in terms of noise. In this embodiment, a preparatory device is provided on the diagonal blade 3a for fastening the cable leading from the housing 2 to the motor 34. Flanges are provided on the edge area of ​​the housing 2 on the load-bearing outlet guide unit 1 on the upstream side and the outflow side, and these flanges advantageously have a variety of fastening preparatory devices. There is a fastening preparatory device 20 on the upstream side flange for fastening the outlet guide unit 1 and thus the fan 57 to the upper instrument or system. Similarly, a fastening preparatory device 21 is provided on the outflow side flange for fastening the outlet guide unit 1 to the upper instrument or system. In addition, a fastening preparatory device 25 for a touch-proof grid is also provided on the outflow side flange, and these fastening preparatory devices can also be similarly provided on the upstream side flange. The touch protection grid can be screwed onto the region 25 in a countersunk manner so that it does not protrude beyond the outlet air guide unit 1 in the axial direction, which enables good operability and good stackability of a plurality of fans 57 .

[0037] The intermediate ring 5 adopts a wave-shaped design and can also adopt a serrated or slotted structure at its outflow side edge 12. It can also be designed as a circle without a wave structure.

[0038] Inside the hub ring 4 in the receiving area 8, the motor is mounted on a motor bearing flange 59 (see FIG. 2 ) integrally mounted on the bearing outlet guide unit 1. In order to enhance and stabilize the connection with the motor, reinforcing ribs 58 are also arranged inside the receiving area 8.

[0039] It is conceivable that in the mold for manufacturing the load-bearing outlet guide unit 1, a replaceable insert is arranged in the area inside the hub ring 4, that is, in the receiving area 8, to realize different interfaces for different motors. In addition to the pitch circle of the bolt holes for fastening the motor, there is also an axial tightening plane for the motor, which changes the axial position of the motor support flange 59 in the receiving area 8.

[0040] In the region of the sprag blade 3a where the provision for fastening the cables is provided, the intermediate ring 5 and the hub ring 4 are provided with openings for routing the electrical connection cables to the stator 36 of the motor 34, which is advantageously an outer rotor motor, further advantageously an electronically commutated motor, which advantageously has an integrated motor electronics system. The housing 2 also advantageously has an opening 50 in this region for the cables to pass through (see, for example, Figure 5a ).

[0041] Figure 2a Shown from the outflow side Figure 1 The axial top view of the fan 57 with the load-bearing outlet air guide unit 1 is shown. Figure 1 In addition, the outer flow channel area 6 penetrated by the strut blades 3, 3a and the inner flow channel area 7 with the inner guide blades 11 can be clearly seen. When the fan 57 is running, the impeller 22 with the blades 19 rotates around the fan axis in the counterclockwise rotation direction 32. The motor 34 is advantageously screwed onto the motor bearing flange 59 in the receiving area 8 by means of the fastening preparation 18.

[0042] The diffuser region 10 extends from the region 29 for the impeller 19 (see Figure 1 ) expands toward the outflow side edge of the housing 2. The intermediate ring 5 also expands slightly from the impeller 19 toward its outflow side edge 12 (see Figure 1 , Figure 4a and Figure 4b ). Therefore, in the present embodiment, both the inner flow channel area 7 and the outer flow channel area 6 are constructed to be diffuse, that is, widen in the flow direction. This is beneficial for high pressure recovery downstream of the impeller 19 and thus high static efficiency of the fan 57.

[0043] Figure 2b for Figure 2aDetailed view in the region of the sprag blade 3, wherein the characteristic radial extension 24 of one or more sprag blades 3, 3a, the characteristic radial extension 26 of one or more impeller blades 22 and the radial rays 31 are shown in each case by characteristic curves in the projection on the plane of the view. The radial extension 24 of the sprag blades 3, 3a is shown here by means of the center line of these sprag blades 3, 3a, for example, as seen in the projection shown, from the radial extension of the leading edge 46 of the sprag blade 3, 3a and from the radial extension of the trailing edge 47 of the sprag blade 3, 3a. Alternatively, the imaginary connecting line of all the center points of gravity of all the cylindrical circumferential surface sections of the sprag blade 3, 3a can be shown using the extension of the leading edge 46 or the trailing edge 47 alone, or using a cylinder coaxial to the fan axis.

[0044] The radial extension 26 of the impeller blade 22 is characterized by means of the extension of its trailing edge 39, wherein the jagged design of the impeller trailing edge 39 is not taken into account and is represented by a "smoothed" line. For example, the center line of the radial extension of the leading edge and the trailing edge or the imaginary connecting line of all the center of gravity of all the cylindrical circumferential surface sections of the fan blade 22 can also be used in the characterization of the radial extension 26 of the impeller blade 22, wherein the cylinder is coaxial with the fan axis.

[0045] Figure 2b At the intersection shown, the angle γ27 between the characteristic radial extension 24 of the strut blades 3, 3a and the characteristic radial extension 26 of the impeller blades 22 is marked, as well as the angle δ28 between the characteristic radial extension 24 of the strut blades 3, 3a and the radial ray 31 from the fan axis. The angle δ28 and the angle γ27 vary slightly with the relative position of the impeller blades 22 and the strut blades 3, 3a, or with the position of the intersection observed in the radial direction. Of particular importance are: the average angle of all possible intersections in the external flow channel area 6, or the angle δ28 or γ27 at the intersection of the external flow channel area 6, for example, at the radial midpoint. For the sake of completeness, it should be clarified that in the present technical solution, the angles δ28 and γ27 should always be understood as absolute values ​​without direction. It is particularly beneficial that the size of the angle γ27 is, in particular, γ>30° or γ>45°, so as to minimize noise generation, in particular rotational noise generation. For the same purpose, it is also advantageous if the angle δ28 is, in particular, δ>20° or δ>35°. Due to the large angle δ28, the rigidity of the bearing-type outlet guide device can be significantly reduced. However, due to the reinforcing effect of the intermediate ring 5, a very high rigidity of the bearing-type outlet guide device 1 is achieved, which is designed with 4 to 8 highly inclined sprag blades 3, 3a with sufficient rigidity, without the risk of the impeller 19 rubbing against the housing 2 or its receiving area 29 for the impeller 19 during operation.

[0046] Furthermore, even in the case of a small angle δ28, a large angle γ27 required for reducing the generation of rotational noise can be achieved. However, this is only possible in the case of a very strong inclination of the radial extension 26 of the impeller blade 22 relative to the radial direction. It has been shown that for an impeller blade 22 that is advantageously injection molded, this is only possible to a limited extent due to the radial deformations that occur during the operation of the impeller blade 22, so that the selection of a sufficiently large angle δ28 may still be necessary and beneficial for low rotational noise generation. In the present embodiment, the strut blade 3 is inclined in its extension from the intermediate ring 5 to the diffuser 10 against the direction of rotation 32 of the impeller. Since the absolute values ​​of the angle γ27 and the angle δ28 are large, it is also conceivable that the strut blade 3 is inclined opposite to the direction of rotation 32. In another conceivable embodiment, different strut blades distributed in the circumferential direction can also be alternately inclined in and against the direction of rotation.

[0047] Figure 3 Shown as viewed from the upstream side Figure 1 , 2a The axial plane top view of the fan 57 with the load-bearing outlet air guide unit 1 is shown. Figure 1 , 2a 2b, the impeller 19 of the fan 57 with its blades 22, which are fastened to a common hub, can be seen particularly clearly here. Advantageously, the impeller is produced in one piece by injection molding. The blades 22 are provided with special structures for noise reduction on their radially outer edges, in particular so-called winglets 38 (see Figure 4a , 4b ). Inside the impeller 19 or in the hub region thereof, the rotor 35 of the electric motor 34 can be seen, to which the impeller 19 is fastened and which drives the impeller 19 during operation of the fan 57. In the hub region of the impeller 19, a hub cap 37 of fluid-mechanically advantageous design is also mounted on the hub of the impeller 19 in order to achieve an aerodynamically and aeroacoustically advantageous design of the fan 57 (see Figure 4a ). When viewed from the flow side, the flow side edge 23 of the intermediate ring 5 of the outlet guide device and the flow side edge 13 of the inner outlet guide vane 11 can also be seen. The direction of rotation 32 is clockwise in the illustrated view.

[0048] Figure 4a Show Figure 1 , 2a3 and 4 show a side view of a fan 57 with a carrier-type outlet air guide unit 1 and a section on a plane passing through the axis, wherein schematically indicated dimensions are shown in the area of ​​the inlet nozzle. In addition to the relevant figures, the contour of the hub cap 37 can also be seen particularly clearly here, which is designed to transition to the hub of the impeller 19 in an aerodynamically suitable manner on the tangential side in a rounded manner, and the hub cap is mounted in the hub area of ​​the impeller 19. The motor 34 is schematically shown, which comprises a stator 36 and a rotor 35. The stator 36 is fastened to a fastening device 18 on a fastening flange 59 inside the receiving area 8 of the carrier-type air guide unit 1. The impeller 19 or its hub is fastened to the rotor 35 of the motor 34 by means of a fastening preparation device 30, preferably by using screws.

[0049] The motor 34 and also the impeller 19 are thus held on the outer casing contour via the inner outlet guide vanes 11, the intermediate ring 5 and the sprag vanes 3, 3a, so that the outlet guide vanes 11, the sprag vanes 3, 3a and finally the entire outlet guide unit 1 can be marked as load-bearing. The impeller 19 extends axially in the casing 2 with its blades 22 and its radially outer ends (preferably with a special contour, the so-called winglets 38) preferably at the height of the cylindrical region 29, wherein there is a small radial spacing and a flow gap between the impeller blades 22 with the winglets 38 and the region 29 of the casing 2.

[0050] The inner air guide element 11 has a design which is particularly advantageous for production by injection molding and demolding from an injection molding mold. It comprises, on its flow-side region 16, an axially inclined region 16 adapted to the flow direction, and, on the outflow region 15, a substantially axially aligned region 15 which can be demolded in the axial direction without undercuts. This design is particularly advantageous in conjunction with the design of the intermediate ring 5 which extends slightly conically and widens radially in the flow direction in terms of demoldability of the component “load-bearing outlet air guide unit 1”.

[0051] The outlet air guide unit 1 is designed to be particularly compact in the radial direction. This means that the ratio of the inlet diameter Da45 of the inlet nozzle 9 (the diameter Da45 at the radially outer starting point of the curved section of the inlet nozzle 9) to the inner diameter Di44 is small, advantageously Da / Di<1.1. This also enables a smaller extension e43 of the outlet air guide unit transverse to the fan axis (the extension e43 can be understood in particular as the side length of a square profile extending transverse to the fan axis, into which the load-bearing outlet air guide unit 1 and thus the fan 57 can be inserted). Advantageously, e / Di<1.2. The fan thus occupies a particularly small installation space in terms of its inner diameter Di44 and thus also in terms of the diameter of its impeller 19 when viewed transversely to its axis. On the contrary, when the installation space is predetermined, a fan 57 with a particularly large inner diameter Di44 and thus a particularly large outer diameter of the impeller 19 can be used, which can be acoustically beneficial at a predetermined operating point.

[0052] When viewed in the radial direction, the outflow side edge of the load-bearing outlet guide unit 1 advantageously does not extend beyond the oncoming side edge. It is further advantageous that the radial extensions of the outflow side edge and the oncoming side edge of the load-bearing outlet guide unit 1 are very close to each other, that is to say (see also Figure 1 ), the inlet nozzle 9 on the flow-side and the diffuser area 10 on the outflow side each maximize the use of the available radial installation space or transportation space (total radial installation space minus the necessary flange area). In addition, during transportation, multiple fans 57 with identical outlet air guide units 1 can be stacked and fastened to each other completely without obstacles, for example, by means of fastening preparation devices 20 and 21 (see Figure 1 ), these fastening preparation means can advantageously at least partially overlap when viewed in a projection onto a plane perpendicular to the fan axis.

[0053] Figure 4b Show Figure 4a Detailed view in the area of ​​the sprag blade 3, in which three characteristic parameters are schematically marked. The axial distance a40 between the sprag blade 3 or its inflow edge 46 and the blade 22 of the impeller 19 or its outflow edge is large, in particular to ensure low rotational noise generation. Here, as a, the average distance on the radial extension of the sprag blade 3 or the minimum axial distance a on its radial extension can also be used. The axial extension b41 of the sprag blade 3 is used as a reference quantity for quantification, and the average value of the radial extension of the sprag blade 3 or is measured at the radial center. It is currently beneficial that a / b>1.0, or more beneficial that: a / b>1.5. In order to achieve a high static efficiency of the fan 57, a large one-sided opening angle α42 of the diffusion area 10 of the housing 2 is selected at the midpoint of the diffusion extension in the curved extension, and α>10° is advantageously preferred. This is possible based on the presence of the intermediate ring 5, which is also slightly widened radially in the flow direction, without having to perform a flow split in the area of ​​the diffuser 10.

[0054] Figure 4c Show Figure 4a Another detailed view in the area of ​​the strut blades 3, in which the undercut areas 48, 49 are schematically indicated by hatching with respect to demolding from the injection mold in a demolding direction parallel to the fan axis. The undercut areas 49 are areas of the diffuser 10 of the housing 2 on the inflow side of the strut blades 3, 3a, wherein the strut blades 3, 3a "block" these areas 49 of the diffuser 10 in order to hinder axial demolding of the molded mold part of the outlet guide unit 1 that is demolded toward the outflow side. Conversely, the diffuser area 10 "blocks" the undercut areas 48 on the strut blades 3, 3a in order to hinder axial demolding of the molded mold part of the outlet guide unit 1 that is demolded toward the inflow side. In particular, the larger opening angle α42 of the diffuser 10 (see Figure 4b ) so that the undercut areas 48, 49 are larger and more pronounced. Special mold shapes are advantageously used, which enable these undercut areas 48, 49 to be demolded, so that they do not have to be filled with material or their design structure has to be changed, which would otherwise be detrimental to efficiency and acoustic performance. For example, slides can be mounted on the molded mold part, which is demolded toward the inflow side and pulled axially out of the component, which slides can perform a possibly superimposed movement radially inwards during demolding and can thus form and shape the undercut areas 48, 49. It is also conceivable that during or before demolding the molded mold part that is demolded toward the outflow side and pulled axially out of the component, a relative rotational movement is carried out between the mold and the component (i.e. the outlet guide unit 1) in order to be able to demold the undercut areas 48, 49, for example by using a rotational movement of the component (i.e. the outlet guide unit 1) during the demolding process.

[0055] Figure 5a Show Figure 1 , 2a , 3 and 4a show a side view of a fan 57 with a load-bearing outlet guide unit 1 and a cross-section on a plane parallel to the axis and the plane of the view, in particular, the diagonal blades 3 can be seen in the cross-section. The wave-shaped design of the outflow side edge 12 of the intermediate ring 5 in this embodiment can be clearly seen. It can be seen here that the edge 12 does not axially extend beyond the housing 2 at any position, and the "trough" is slightly indented into the housing with a small distance from the axial edge. Figure 1 As described, a touch protection grid is advantageously mounted on the outflow side, which advantageously does not protrude axially from the housing 2. The radially extending struts of such a touch protection grid can then extend in the "trough" region, i.e., in the gap, of the outflow-side edge 12 of the intermediate ring 5. A gap 50 can also be seen on the housing 2, through which the cable can be guided to the motor 34.

[0056] Figure 5b Show Figure 5aDetailed view of the region in which the strut blade 3 is visible, wherein four characteristic parameters are schematically shown. The axial extension b41 of the strut blade 3 has been Figure 4b Description. This axial extension, together with the thickness t54 of the strut blade 3, also plays an important role in the rigidity and strength of the load-bearing outlet guide unit 1, because a relatively small number, advantageously 4-8 strut blades, in particular, must hold the entire motor 24, the impeller 19, the built-in guide device with the intermediate ring 5, the hub ring 4 and the inner guide blades 11 on the housing 2. It is important that the rigidity moment (area moment of inertia) of the strut blade 3 in the cross section is sufficiently large. In order to ensure that the axial extension b41 of the strut blade 3 is not too large for the sake of low rotational noise generation, the thickness t54 of the strut blade 3 is advantageously designed to be larger. In terms of quantity, it is particularly advantageous that the maximum thickness t54 of a strut blade 3 should be selected to be greater than 20% of its axial extension b41. This is achieved under the condition of taking into account the aerodynamically advantageous design of the cross section of the strut blade 3 (as viewed in section or on a section with a cylindrical circumference coaxial with the fan). In this cross section, the cross section of the sprag blade 3 is designed to be elongated similar to the cross section of the load-bearing blade, with a largely rounded flow edge 46 and a thinner trailing edge 47. Here, the center line 60 of the cross section of the sprag blade 3 has a similar cross section to the upstream impeller 19 and its blades 22 (see Figure 5a ). In particular, the center line 60 is significantly inclined relative to the parallel line 53 of the fan axis, because the outflow from the impeller 19 can have a significant circumferential component in terms of flow velocity. The inclination angle β1 of the center line 60 of the cross section of the sprag blade 3 at the oncoming edge 46 relative to the parallel line 53 of the fan axis is advantageously greater than 20°, so as to generate as little resistance to the flow as possible and generate as little noise as possible.

[0057] It is also clear that the sprag blade 3 causes no or almost no flow deflection, also in order to minimize noise and / or avoid flow separation in the diffusion area 10. Therefore, the difference between the angle β1 (51) and the angle β2 of the center line 60 of the cross section of the sprag blade 3 at its outflow edge 47 relative to the parallel line 53 of the fan axis is close to 0°, or at most very small in absolute value, i.e. |β2-β1|<8°.

[0058] Figure 6a A side view and a section on a plane passing through the axis of another embodiment of a load-bearing outlet guide unit 1 are shown, wherein demoulding wedges 55 are provided in the region of the diffuser 10 for easier demoulding. Figure 6b These demoulding wedges 55 are Figure 4cThe demoulding wedges are essentially a material thickening or material transfer from the "ideal" body of revolution contour of the housing 2 in the region of the diffuser 10 inwardly in the axial direction, in particular in the local region of the oncoming side of the strut blades 3. These demoulding wedges are used for easier demoulding of the load-bearing outlet guide unit 1, which is advantageously integrally formed in the injection molding mold, and enable the following possibilities: Figure 4c The embodiment shown shows a simpler mold technology. However, these demoulding cams 55 can lead to negative effects such as loss of hydrostatic efficiency and noise generation during operation.

[0059] exist Figure 6a and 6b In the embodiment of the load-bearing outlet guide unit 1 shown, the outflow side edge 12 of the intermediate ring 5 does not have a wavy, sawtooth or other contour, but adopts a relatively flat circular contour. However, in order to be able to install the anti-touch grid axially inside the load-bearing outlet guide unit 1 without axial protrusion, the outflow side edge 12 of the intermediate ring 5 is axially concave inwardly relative to the axial outflow side edge in the area of ​​the housing 2.

[0060] Figure 7a and 7b Axial plane top views of a fan 57 having a load-bearing outlet guide unit 1 of another embodiment are shown respectively as viewed from the outflow side, wherein curves of flow disturbance 56 in the wake of the impeller 19 downstream of the impeller blade trailing edge 39 on two different planes perpendicular to the axis obtained by means of flow simulation are shown.

[0061] exist Figure 7a , disturbances 56 are marked in a plane a few millimeters downstream of the trailing edges 39 of the blades 22 of the impeller 19. These disturbances 56 are generated by the impeller and therefore have a radial form very similar to the radial extension of the impeller blades 22, in particular at their trailing edges 39.

[0062] exist Figure 7b In the diagram, these disturbances 56 are marked further upstream on a plane a few millimeters upstream of the sprag blade 3 or its oncoming edge 46. In this plane, the radial shape of the disturbance 56 is still similar to the radial extension of the trailing edge 39, but due to the circumferential component of the flow, it is slightly offset in the circumferential direction and its intensity is also weakened. This is due to the relatively large distance between the leading edge 46 of the sprag blade 3 and the trailing edge 39 of the impeller blade 22.

[0063] According to the understanding based on the present technical solution, the key to achieving low noise generation is that these disturbances should in any case not propagate in a direction parallel to the leading edge 46 of the strut blade 3 as much as possible, and thus the disturbances do not simultaneously impact the leading edge 46 of the strut blade 3 along the entire radial extension in the radial direction. Figure 2b The relationship shown is achieved because the flow disturbance 56 moves downstream to the sprag blade 3 and its leading edge 46 almost parallel to the radial extension of the trailing edge 39 of the blade 22 of the impeller 19 in a section on a viewing plane perpendicular to the fan axis. In addition, Figure 4b The large distance shown between the leading edge 46 of the sprag blade 3 and the trailing edge 39 of the impeller blade 22 helps the flow disturbance 56 to be attenuated when it impinges on the sprag blade 3 .

[0064] Reference numerals list

[0065] 1 Load-bearing outlet guide unit

[0066] 2 Shell of outlet guide unit

[0067] 3 Braced blades

[0068] 3a Braced blade with fastening provision for cables

[0069] 4 Hub ring, especially the ring of the outlet guide unit

[0070] 5. The middle ring of the outlet guide unit or diffuser

[0071] 6 External flow channel area

[0072] 7 Internal flow channel area

[0073] 8 Receiving area inside the wheel hub ring

[0074] 9 Inlet nozzle

[0075] 10 External diffusion wall

[0076] 11Internal guide elements, guide vanes

[0077] 12 Outflow edge of the middle ring

[0078] 13 Flow-incoming edge of internal flow-guiding element

[0079] 14 Outflow edge of internal flow guide element

[0080] 15 Axial alignment of the internal flow guide element

[0081] 16 Inclined piece of guide element

[0082] 17 Unlimited

[0083] 18 Fastening preparation in the receiving area

[0084] 19 Impeller

[0085] 20Preparatory device for fastening the outlet guide element on the upstream system on the flow side

[0086] 21. Preparatory device for fastening outlet guide unit components on the outflow side of the upper system

[0087] 22 Impeller blades

[0088] 23 The flow-side edge of the middle ring of the outlet guide unit

[0089] 24 The braced blades are the extension of a line projected onto a plane perpendicular to the fan axis

[0090] 25 Fastening preparation device for protective grille on outflow side

[0091] 26 Impeller blades as extension of a line projected onto a plane perpendicular to the fan axis

[0092] 27 Observed in the projection on the plane perpendicular to the fan axis, the extension of the diagonal blade and the extension of the impeller blade

[0093] The included angle γ28 between the blade extension and the radial ray extension is observed in the projection on the plane perpendicular to the fan axis.

[0094] The angle δ29 between the impeller area

[0095] 30 Preparatory device for fastening the motor to the impeller

[0096] 31 Radial rays triggered from the fan axis

[0097] 32 Impeller rotation direction

[0098] 33 Unlimited

[0099] 34 Motor

[0100] 35 Motor rotor

[0101] 36 Motor stator

[0102] 37 Hubcap

[0103] 38 Winglets on impeller blades

[0104] 39 Outflow edge of the impeller blade 40 Axial distance a between the trailing edge of the impeller blade and the leading edge of the impeller blade 41 Axial extension b of the impeller blade 42 One-side opening angle α of the diffuser 43 Extension e of the outlet air guide unit transverse to the fan axis 44 Inner diameter Di of the housing of the outlet air guide device in the region of the impeller 45 Outer diameter Da of the outer start of the curvature of the inlet nozzle 9 46 Oncoming edge of the brace blade

[0105] 47 Outflow edge of the braced blade

[0106] 48 Undercut area of ​​the braced blade

[0107] 49 undercut area of ​​the diffuser wall 50 cable channel in the diffuser wall area of ​​the outlet guide device 51 incident flow angle β1 of the diagonal blade

[0108] 52 The outflow angle of the diagonal blade β2

[0109] 53 Parallel line of the fan axis 54 Thickness t of the sprag blade 55 Demolding wedge / demolding area on the housing in the region of the diffuser wall 56 Flow disturbance in the wake of the impeller blade

[0110] 57 fan, axial flow fan

[0111] 58 Reinforcing ribs in the receiving area for the electric motor

[0112] 59 Fastening flange for motor 60 Passing through the center line of the cross section of the diagonal blade

Claims

1. Outlet guide unit for a fan, the fan having at least one impeller including impeller blades, the outlet guide unit having an outer housing and at least one outlet guide wheel with internal guide blades, wherein, the outlet guide wheel has an intermediate ring which is preferably concentrically held in / on the housing by means of at least three circumferentially distributed diagonal support blades.

2. The outlet guide unit according to claim 1, characterized in that, the number of the diagonal support blades is less than the number of the internal guide blades, preferably, there are provided diagonal support blades less than half of the internal guide blades, in particular less than 9.

3. The outlet guide device according to claim 1 or 2, characterized in that, the diagonal support blades are designed thicker than the internal guide blades.

4. The outlet guide device according to any one of claims 1 to 3, characterized in that, the diagonal support blades have a relatively large thickness with respect to their axial extension, in particular greater than 20% of their axial extension.

5. The outlet guide device according to any one of claims 1 to 4, characterized in that, the diagonal support blades have a smaller hydrodynamically effective area compared to the internal guide blades.

6. The outlet guide device according to any one of claims 1 to 5, characterized in that, the diagonal support blades are inclined with respect to an imaginary radial ray such that these diagonal support blades have a significant inclination with respect to the trailing edge of the impeller blades.

7. The outlet guide device according to any one of claims 1 to 6, characterized in that, the diagonal support blades are inclined in a cross-section on a cylindrical circumferential surface coaxial with the fan axis, however, without generating or only generating a weak flow turning.

8. The outlet guide device according to any one of claims 1 to 7, characterized in that, the diagonal support blades are inclined, oriented and dimensioned in a cross-section, for example in a cross-section on a cylindrical circumferential surface coaxial with the fan axis, such that these diagonal support blades generate as little flow resistance as possible with respect to the swirl flowing out from the impeller of the fan, wherein no or at most a small flow turning occurs on the diagonal support blades.

9. The outlet guide device according to any one of claims 1 to 8, characterized in that, the leading edge of the diagonal support blades has a greater distance from the trailing edge of the impeller blades, and this distance is preferably greater than the axial extension of the diagonal support blades in the axial direction.

10. The outlet guide device according to any one of claims 1 to 9, characterized in that, the diagonal support blades are fastened on the outer housing or are constructed in the range of a diffuser or a diffuser region, preferably away from the diffuser inlet.

11. The outlet guide device according to any one of claims 1 to 10, characterized in that a cooling structure preferably integrated in the outlet guide wheel, and the outlet guide wheel can be constructed as a one-piece.

12. The outlet guide device according to any one of claims 1 to 11, characterized in that the main components or all components are integrally manufactured by casting or injection molding technology from plastics, preferably from fiber-reinforced thermoplastics.

13. The outlet guide device according to any one of claims 1 to 12, characterized in that load-bearing function.

14. A fan, in particular an axial flow, radial flow or mixed flow fan, comprising an outlet guide device according to one of claims 1 to 13, which is arranged downstream of the fan in terms of flow technology.

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