EP3775571B1 - Fan and inflow grille for a fan - Google Patents

Description

The present invention relates to a fan (axial, radial or diagonal fan) with an impeller and a guide device in the flow path in front of the impeller, preferably in front of the inlet area of an inlet nozzle, wherein the guide device is designed as an inflow grille with flat webs and wherein the webs form a plurality of grid-cell-like flow channels. Furthermore, the invention relates to a special guide device which is designed in the sense of an inflow grille with flat webs.

A generic fan with inflow-side guide vane is, for example, made of WO 03/054395 A1 or from WO 2015/124237 A1 known. The guide device provided there serves primarily to even out the flow, and in particular to reduce noise. The known guide device generates a pre-swirl in the direction of rotation of the impeller. It is important to note that acoustic improvements are regularly accompanied by losses in air performance and efficiency. The guide device provided there is also very complex to manufacture.

So-called guide vanes are already known from practice, which serve to improve efficiency and/or air performance. However, these guide vanes have acoustic disadvantages and are complicated to construct and install in the respective fan products. They are usually installed in front of fan impellers in a cylindrical installation space with a diameter approximately the same as the fan impeller and therefore do not have a significantly larger flow area than the fan. As a result, the air speeds in the area of these guide vanes are relatively high, which in particular causes the acoustic disadvantages.

Basically, the invention is based on the following technical problem.

Fans often react to disturbed air flow with increased noise. In many fan applications, for example in controlled residential ventilation (KWL), the regular compactness requirements inevitably result in disturbed inflow conditions. The resulting noise, which often has a large tonal component, is usually low-frequency. Noise reduction of this low-frequency noise is essential, particularly in ventilation devices.

It is also already known to significantly reduce noise with so-called flow straighteners in the event of a disturbed inflow. However, such flow straighteners cause not inconsiderable pressure losses and also require a large amount of installation space. The present invention is therefore based on the task of designing and developing a fan in such a way that noise is reduced in the event of a disturbed inflow. The fan should be compact and have only extremely low pressure losses. In addition, a guide device, in particular an inflow grille or guide grille, should be specified which meets the above requirements and which can be manufactured using plastic injection molding with economical tooling. It should be dimensionally stable and be able to advantageously take on the function of an upstream contact protection grille.

The above object is achieved with respect to a fan according to the invention by alternative feature combinations according to the features of the independent claims 1 and 3. With respect to the inlet grille according to the invention, the above object is achieved by the features of claim 10, which refers to the claims relating to the fan.

In a first variant according to claim 1, the webs extend predominantly between preferably two branches or between one branch in each edge area. Preferably three webs meet at each branch. These features form very special grid-cell-like flow channels that are suitable for reducing noise in the event of a disturbed inflow.

The further subordinate claim 3 claims a further alternative, according to which the inflow grille has a basket-like contour, wherein this configuration relates to the outer and/or inner envelope surface of the inflow grille.

The same applies to the design of the inlet grille itself, which is defined in the subordinate claim 10 with reference to the claims relating to the fan.

The underlying independent claims are the basic idea of providing an inflow grille or inlet grille in front of the inlet nozzle of a fan in order to reduce the noise generated when the fan is operating in the event of a disruption to the inflow. The inflow grille is defined by flat webs, whereby the webs are arranged in such a way that grid-cell-like flow channels are created. By cleverly combining the webs, which form branches and nodes, advantageous geometries can be realized, for example in that the flow channels have a honeycomb-like cross-section. The term "honeycomb-like" is to be understood in the broadest sense, so that it also includes polygons, for example grid cells with a square, five-sided or hexagonal or polygonal cross-section.

According to the previously discussed grid cell-like flow channels, it is further advantageous that the inflow grille has a basket-like contour, whereby the contour can refer to both the outer and the inner envelope surface of the inflow grille.

An inflow grille of the type mentioned above is suitable for the radial inflow in the area close to the nozzle plate. The flow channels have a beneficial effect on low pressure losses. The basket-like outer contour is also advantageous for demoldability in the context of an injection molding technique that is used primarily for plastic parts. In addition, compact grilles with the corresponding properties can be produced.

The basket-like outer contour is particularly advantageous if it is continuous and curved. The grid webs should be as thin as possible, for example in the range of 0.25 mm to 1 mm web thickness. In the direction of flow they should have a depth of at least 5 mm (hence the term "flat web" chosen in the claims).

Another advantage is that the grid bars form a non-structured grid in which honeycomb-like grid cells are combined with one another. As already mentioned, the grid cells can be polygonal and combined with one another or with one another. This allows minimal obstruction by grid bars to be achieved, particularly when a certain maximum grid width is necessary due to the required noise reduction or taking into account contact protection aspects, which leads to low pressure and efficiency losses.

The inlet grille advantageously extends over the entire area up to the imaginary extension of the fan axis, so it has no or no particularly large opening in the inner area. In light of the teaching of the invention, such a central opening is not necessary, and can even be avoided, provided the inlet grille also provides protection against contact. It has also been found that a central opening is detrimental to minimizing noise and improving the stability of the grille.

The special design of the inflow grille is particularly advantageous, not only in terms of the grid-like flow channels, but also in terms of the continuous and curved outer contour. Honeycomb elements with 4, 5 or 6 corners allow unstructured grilles to be created, with variable grille widths being possible across the entire inflow grille, depending on requirements.

The inlet grille according to the invention is intended for use in an axial, radial or diagonal fan and is constructed in accordance with the above statements.

Fig. 1

in perspektivischer Ansicht von der Zuströmseite aus gesehen ein Ausführungsbeispiel eines erfindungsgemäßen Einströmgitters,

Fig. 1a

in perspektivischer Ansicht eine schematische Detaildarstellung einer aus Stegen aufgebauten Zelle gemäß Fig. 1, wobei charakteristische Abmessungen der Stege und Zellen gekennzeichnet sind,

Fig. 2

in perspektivischer Ansicht von der Abströmseite aus gesehen, das Einströmgitter aus Fig. 1,

Fig. 3

in axialer Draufsicht, von der Zuströmseite aus gesehen, das Einströmgitter aus Fig. 1 und 2,

Fig. 4

in axialer Draufsicht, von der Abströmseite aus gesehen, das Einströmgitter aus Fig. 1 bis 3,

Fig. 5

in einer Seitenansicht und im Schnitt an einer Ebene durch die Achse das Einströmgitter gemäß Fig. 1 bis 4, wobei charakteristische Abmessungen des Einströmgitters eingezeichnet sind,

Fig. 6

in perspektivischer Ansicht von der Zuströmseite aus gesehen ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Einströmgitters,

Fig. 7

in axialer Draufsicht, von der Abströmseite aus gesehen, das Einströmgitter aus Fig. 6,

Fig. 8

in perspektivischer Ansicht von der Zuströmseite aus gesehen ein weiteres Ausführungsbeispiel eines Einströmgitters,

Fig. 9

in perspektivischer Ansicht von der Abströmseite aus gesehen, das Einströmgitter aus Fig. 8,

Fig. 10

in axialer Draufsicht, von der Zuströmseite aus gesehen, das Einströmgitter aus Fig. 8 und 9,

Fig. 11

in einer Seitenansicht und im Schnitt an einer Ebene durch die Achse das Einströmgitter gemäß Fig. 8 bis 10, wobei charakteristische Abmessungen des Einströmgitters eingezeichnet sind,

Fig. 12

in einer Seitenansicht und im Schnitt an einer Ebene durch die Achse ein weiteres Beispiel eines erfindungsgemäßen Einströmgitters mit gekrümmten Stegen,

Fig. 13

in perspektivischer Ansicht von der Zuströmseite aus gesehen ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Einströmgitters mit einem zentralen, geschlossenen Anspritzbereich,

Fig. 14

in axialer Draufsicht, von der Zuströmseite aus gesehen, das Einströmgitter aus Fig. 13,

Fig. 15

in einer Seitenansicht das Einströmgitter gemäß Fig. 13 und 14,

Fig. 16

in einer Seitenansicht und im Schnitt an einer Ebene durch die Achse das Einströmgitter gemäß Fig. 13 bis 15,

Fig. 17

in perspektivischer, schematischer Ansicht von der Zuströmseite aus gesehen und geschnitten an einer Ebene durch die Achse einen Ventilator mit Motor, Laufrad, Einlaufdüse, einer Düsenplatte und dem Einströmgitter gemäß Fig. 13 bis 16.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, reference is made on the one hand to the claims subordinate to claim 1 and on the other hand to the following explanation of preferred embodiments of an inflow grille according to the invention with reference to the drawing. In connection with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and developments of the teaching are also explained. The drawing shows

Fig.1

in perspective view from the inflow side an embodiment of an inflow grille according to the invention,

Fig. 1a

in perspective view a schematic detailed representation of a cell constructed from webs according to Fig.1 , where characteristic dimensions of the webs and cells are marked,

Fig. 2

in perspective view from the downstream side, the inlet grille made of Fig.1 ,

Fig.3

in axial plan view, seen from the inflow side, the inflow grille made of Fig.1 and 2 ,

Fig.4

in axial plan view, seen from the downstream side, the inlet grille made of Fig. 1 to 3 ,

Fig.5

in a side view and in section on a plane through the axis the inlet grille according to Fig. 1 to 4 , where characteristic dimensions of the inlet grille are shown,

Fig.6

in perspective view from the inflow side, another embodiment of an inflow grille according to the invention,

Fig.7

in axial plan view, seen from the downstream side, the inlet grille made of Fig.6 ,

Fig.8

in perspective view from the inflow side another embodiment of an inflow grille,

Fig.9

in perspective view from the downstream side, the inlet grille made of Fig.8 ,

Fig.10

in axial plan view, seen from the inflow side, the inflow grille made of Fig.8 and 9 ,

Fig. 11

in a side view and in section on a plane through the axis the inlet grille according to Fig. 8 to 10 , where characteristic dimensions of the inlet grille are shown,

Fig. 12

in a side view and in section on a plane through the axis another example of an inflow grille according to the invention with curved webs,

Fig. 13

in perspective view from the inflow side, another embodiment of an inflow grille according to the invention with a central, closed injection area,

Fig. 14

in axial plan view, seen from the inflow side, the inflow grille made of Fig. 13 ,

Fig. 15

in a side view the inlet grille according to Fig. 13 and 14 ,

Fig. 16

in a side view and in section on a plane through the axis the inlet grille according to Fig. 13 to 15 ,

Fig. 17

in perspective, schematic view seen from the inflow side and cut on a plane through the axis, a fan with motor, impeller, inlet nozzle, a nozzle plate and the inflow grille according to Fig. 13 to 16 .

Fig.1 shows an embodiment of an inflow grille 1 in a perspective view from the front, ie seen from the inflow side. The inflow grille 1 is similar to the illustration in Fig. 17 advantageously mounted in front of the inlet nozzle 2 of a fan so that its axis roughly coincides with the rotation axis of the fan. When the fan is in operation, the air first flows through the inlet grille 1 into the inlet nozzle 2 before it experiences a total pressure increase as it flows through an impeller 3 of the fan, which is driven by a motor 4. The inlet grille 1 evens out the incoming air, thereby reducing the noise generated in the impeller.

The inlet grille 1 consists of a large number of webs 5 which define grille cells 6. The grille cells 6 are flowed through when the fan is operating, i.e. they form flow channels. The incoming air has a lower speed in an area in front of an inlet nozzle 2 than inside an inlet nozzle 2, since the area flowed through by the air mass flow conveyed by the fan is larger in an area in front of an inlet nozzle 2 than in an inlet nozzle 2. The inlet grille 1 is used in such an area of relatively low flow speeds, i.e. the flow speed at the inlet grille 1 is lower than the flow speed in the inlet nozzle 2. This keeps flow losses and noise generation at the inlet grille 1 to a minimum.

However, since the inflow in an area in front of an inlet nozzle 2 is not flat or not predominantly parallel to the axis, it is of great advantage not to make the contour of the inflow grille 1 completely flat. The contour can be described by the outer envelope surface 7 and/or the inner envelope surface 8 ( Fig. 2 ) of the inflow grille 1. These envelope surfaces 7, 8 are defined by the totality of the inflow and outflow end faces 7a and 8a of the webs 5 (see Fig. 1a ), supplemented by imaginary continuous or curvature-continuous completions in the area of the flow channels 6.

Fig. 1a shows a detailed, enlarged view of a section of the inlet grille 1 from Fig.1 . The webs 5 have a significant depth t (9) in the direction of flow, advantageously around 6-20 mm. For this reason, the webs 5 are also referred to as "flat" webs. A grid cell 6 is also characterized by a cell width w (12), for example defined by the radius of the largest in-sphere of the cell 6. In order to achieve good acoustic values, a small grid width w (12) is advantageous, for example a value of w (12) of no more than two to three times the web depth t (12) for the majority of the cells 6 of an inflow grid 1. The inflow grid 1 in the embodiment according to Fig.1 also represents a contact protection device which, in accordance with regulations and standards, must comply with requirements for the cell width w (12) depending on the cell shape and the distance of the cell 6 from a rotating part of the fan. This additionally limits the size of the cell width w (12) upwards.

For a low pressure and efficiency loss, it is advantageous to block the flow area as little as possible by the grid webs 5. This can be achieved by thin webs (web thickness d (10) advantageously predominantly <= 2 mm [<=1 mm]) and/or by minimizing the total web length (sum of all web lengths I (11) of an inflow grid (1). The web lengths I are determined based on the neutral fibers 13, advantageously on the outer or inner envelope surface 7 or 8). An "unstructured" grid structure with honeycomb-like cells 6 as in the exemplary embodiment can be very advantageous for the required total web length under the described conditions for the maximum grid width w (12).

In Fig. 2 the inlet grille 1 is according to Fig.1 shown in a perspective view from the downstream side. The inlet grille 1 has fastening areas 18 on the outside, which serve to attach the inlet grille 1 to the inlet nozzle 2 or the nozzle plate 32 ( Fig. 17 ) to be attached. For the There are various options for designing the fastening areas 18. Possible fastenings are screws, rivets, snap hooks, bayonet locks, gluing, snapping, Velcro or others. In the example, a screw hole is provided on each of the four fastening areas 18.

In the view according to Fig. 2 the basket-like contour of the inner envelope surface 8 of the inflow grille 1 is clearly visible. This contour extends along the outer circumference for a certain distance, preferably more than 10 mm or more than 8% of the outer diameter D (20) ( Fig.5 ), approximately parallel to the imaginary central axis, approximately on a cylinder jacket (cylinder jacket-like region 34). The cells 19 of the outer row are located in this cylinder jacket-like region 34, two adjacent cells of which are separated from one another by a web 35 of the outer row. The cells 19 of the outer row have a rather elongated shape. In order to ensure contact protection and to achieve acoustic improvements, the cell widths w (in-sphere radii, for the cells 19 of the outer row essentially determined by the distance between two adjacent webs 35 of the outer row) of these cells are rather smaller than the in-sphere radii of the other cells 6. In a region close to the axis, the contour is flat or flat, approximately orthogonal to the axis (flat region 33). The transition from the flat region 33 to the cylinder jacket-like region 34 takes place via a short transition region 24, which is curved in the exemplary embodiment. In the exemplary embodiment, the outer envelope surface 7 and the inner envelope surface 8 run approximately parallel. The division of the regions 33, 34, 24 can be carried out based on the outer and/or inner envelope surface 7 or 8.

In Fig.3 the inlet grille 1 is according to Fig.1 and 2 in axial plan view from the front (seen from the inflow side). Such an inflow grille 1 is advantageously manufactured using plastic injection molding. It is also advantageous to view the grille from Fig.3 also to be chosen as the demolding direction for an injection molding tool in order to keep the tool complexity low. During the demolding process, one tool part then moves relative to the inflow grille 1 towards the viewer, advantageously the nozzle side of the tool, and another tool part moves away from the viewer. The injection molding tool advantageously has no further slides for the sake of ease of manufacture.

The fastening areas 18 are designed in conjunction with the grid webs 5 in such a way that they can be removed from an injection molding tool without undercuts in a slide direction parallel to the axis (corresponds to the viewing direction in this illustration). It can be seen that the grid webs 5 are not partially aligned parallel to the central axis (= viewing direction), but rather their alignment is optimally adapted to the inflow conditions. The webs can also advantageously have a curvature in order to optimally guide the flow. As an example, a web 29 is marked, which is an axially aligned web, i.e. it is aligned parallel to the axis (viewing and slide direction), which makes it easier to demold it. Axially aligned webs 29 are advantageously provided with a demolding slope. However, there are also axially non-aligned webs 30, 30a, since all webs 5 are adapted as optimally as possible to the flow directions. The two radially outermost rows of grid webs 5, which run approximately in the circumferential direction, run in the transition area 24 of the envelope surfaces 7 or 8 and are coordinated with one another in such a way that only small or no undercut areas are created, i.e. they do not cover each other or only cover each other slightly when viewed in the axial direction. In the exemplary embodiment shown, there is, for example, a small undercut area 17 in the interaction of the web 5a of the radially outermost row of webs 5 and the web 5b of the second row of webs 5, since these two webs have a small overlap area in the viewing direction. If a suitable, more elastic material is selected, small undercuts can be created and still demolded in the axial direction with a simple open-close tool. This makes it easy and economical to create a contour that is particularly optimized in terms of flow. Furthermore, there is a slight undercut area in the branching area 15 between the two axially non-aligned webs 30 and 30a, since the x-component of their surface normal vectors has a different sign. This slight undercut can also be demolded with a simple open-close tool if a suitable material is selected.

In this embodiment, the cells in the area near the axis are smaller than those in the area away from the axis. The cell size or cell width w (12, see Fig.2 ) is optimized in each case with regard to the requirements regarding compliance the contact protection regulations and with regard to the acoustic improvements or flow equalization to be achieved. The distribution of the cells is optimized using a special algorithm. A wide variety of cell contours occur (when viewed on one of the envelope surfaces 7 or 8), in particular, but not exclusively, regular and irregular 4-6 corners. Approximately, each cell (when viewed on an envelope surface 7 or 8) describes a range of points which are those that are closest to an imaginary central point (on the envelope surface) compared to the imaginary central points of all other cells. The structure of the grid 1 is therefore also characterized by the fact that in the majority of branching areas 15 exactly 3 webs 5 meet, in far fewer branching areas 4 webs 5 meet. Furthermore, there are no relatively small cells at the edge with a flow area of less than 50% with respect to the flow area of one of their neighboring cells, which are caused by an effect of "cutting through outer cells with the edge".

According to Fig.4 The inlet grille 1 is made of Fig. 1 to 3 shown in axial plan view from behind (seen from the downstream side). The webs 35 of the outer row, which are aligned in the axial direction, have a free end 14. This allows them to be demolded by a tool slide which moves in the direction of the downstream side (towards the viewer) when opened. The fact that the ends 14 of the outer webs 35 are not connected is disadvantageous in terms of strength and dimensional stability, but can be compensated for by using a high-quality material or by using large wall thicknesses d (10).

The inflow grille 1 in the exemplary embodiment is made up of four identical segments. This represents a significant advantage, especially in the design of the component and the tool required for production, since the number of differently designed grille cells 6 is thereby reduced by a factor of 4 (factor = number of segments). As a result of this segmentation, the flow pattern is independent of the orientation (quadrant) of the inflow grille 1 during assembly. A different number of segments is also possible. The segments can have slight differences from one another, for example in the area of the fastening provisions, if their number does not correspond to the number of segments. corresponds, or in an inner area close to the axis, in which segmentation may be more difficult under certain circumstances. Particularly with large external diameters, segmentation can be used advantageously to assemble inlet grilles 1 from several injection-molded segments, e.g. by clipping, locking, screwing, gluing, by fastening to the nozzle plate, or the like. With this multi-part approach, it is also conceivable to produce a separate, different, central part in addition to the actual identical segments, which then requires its own injection molding tool. The central part can, however, be of a simple design, in particular even or flat.

In the embodiment shown, there is a central branching point 16 of 4 (= number of segments in the embodiment) webs 5 in the center, on the axis.

Fig.5 shows the inlet grille 1 according to the Fig. 1 to 4 in a side view and in section on a plane through the axis. The course of the basket-like contour of the inflow-side and outflow-side envelope surfaces 7 and 8 is clearly visible. The outer envelope surface 7 has an outer diameter D (20), which is also referred to as the diameter D (20) of the inflow grille 1, whereby the diameter of the fastening areas 18 is not taken into account here. The outer envelope surface 7 and inner envelope surface 8 run approximately parallel to one another in the exemplary embodiment. The distance between the envelope surfaces 7 and 8 is advantageously 6 mm to 18 mm or is approximately 3%-10% of the diameter D (20) of the inflow grille 1. In the areas at the top and bottom, close to the screw-on plane, the contour runs approximately parallel to the axis for a distance (cylinder jacket-like part 34). The transition to the flat area 33, on the right in the illustration (inflow side), takes place continuously and curved in a transition area 24. The transition region 24 has a small extension in the radial direction of less than 12.5% of the outer diameter D (20). The flat region 33 has a diameter DE (21) which is advantageously relatively large and has at least 75% of the value of the outer diameter D (20). The inflow grille 1 has an axial height H (22), with the cylinder jacket-like region on the outer envelope surface 7 has an axial extension of HZ(23). HZ (23) is advantageously larger than 6% of the diameter D (20).

The basket-like contour of the inflow grille 1 or its envelope surfaces 7, 8 is well adapted in terms of flow conditions. In the cylinder jacket-like area 34, air is expected to flow in more in a radial direction from the nozzle plate 32, which, due to the cylinder jacket-like shape of the grille 1 in this area 34, can pass through it approximately transversely to the envelope surfaces 7, 8 over a short path and thus with low flow losses. In the flat or level area 33, an axial inflow is expected, which then also flows through the grille 1 over a short path transversely to the envelope surfaces 7, 8. The compactly designed transition area 24 with a small extension enables a low installation height H (22) to be achieved, which is advantageous for a small space requirement of the inflow grille 1. The axial installation height H (22) is advantageously no greater than 25% of D (20).

Furthermore, the targeted alignment of the webs can be clearly seen, which do not always run exactly perpendicular to the envelope surfaces, but are sometimes significantly different from this and optimally adapted to the exact inflow direction. In the exemplary embodiment, the webs 5 are not curved in the flow direction. However, this is certainly conceivable in other embodiments. In the radially outer webs 35, the outer ends 14 are open, i.e. not connected to one another (except at the fastening areas 18).

Fig.6 shows another embodiment of an inflow grille 1 in a perspective view from the front (from the inflow side). Unlike the embodiment according to the Fig. 1-5 the outer ends 14 of the webs 35 of the outer row are connected via an outer connecting ring 25. This increases the dimensional stability of the outer webs 35, which can be advantageous with regard to compliance with the requirements for contact protection, especially when softer or more elastic materials are used. The outer connecting ring 25 can also be advantageous for the filling behavior of an injection molding tool. The connecting ring 25 is connected to the webs 35 by means of a connection 27. This connection is designed as an extension area the outer webs 35 are designed in the form of a curve with a large curve radius > 3 mm. The fastening areas 18 are integrated into the connecting ring 25.

In the exemplary embodiment, the connecting ring 25 lies in a plane that represents the screw-on plane toward the nozzle 2 or the nozzle plate 32. In other advantageous embodiments, the connecting ring 25 can run away from the fastening areas 35 and axially offset from the screw-on plane. This creates space between the nozzle 2 or the nozzle plate 32 and the connecting ring 25 when assembled. The presence of such space can be necessary for existing screw heads with which, for example, the nozzle 2 and the nozzle plate 32 can be screwed together, or in order to be able to position pressure extraction devices. If the connecting ring runs axially offset from the screw-on plane in areas, some or all of the webs 35 of the outer row can protrude beyond this toward the nozzle 2 or the nozzle plate 32, or end at the connecting web 25 when viewed in the axial direction. Additional webs can also be attached in the area between the connecting web and the screw-on plane. In other embodiments, it is also conceivable that the connecting ring 25 is interrupted in some areas and thus individual outer ribs 35 with open outer ends 14 are present. These outer ribs 35 with open outer ends 14 can also be shortened so that the outer ends 14 are at a distance from the screw-on plane. This can also serve to create space for screw heads, pressure tapping devices or the like between the screw-on plane and the inflow grille 1 in the assembled state.

In Fig.7 the inlet grille 1 is according to Fig.6 in axial plan view from behind (seen from the downstream side). In this illustration, it is particularly evident that the connecting ring 25 is located radially completely outside all webs 5, with the exception of the axially aligned webs 35 of the outer row with their connections 27 to the connecting ring 25. This is particularly advantageous for the demoldability of the grid 1 from a simple open-close injection molding tool. Examples are shown in Fig.7 four identical cells 26 of the grid 1, which is made up of four identical segments. Since the number of different cells is greatly reduced by such segmentation, the effort involved in the construction of the grille 1 and especially the associated injection molding tool.

Fig.8 shows an inflow grille 1 in a perspective view from the front (from the inflow side). The cells 6 and the webs 5 are neither arranged in a honeycomb-like manner nor unstructured, but rather radially extending webs 5 are formed that run over the circumference. Four radially extending webs 5 meet in the central axis area at a central branching point 16. The number of webs 5 that meet per branching area 15 is mainly 4. The inflow grille 1 has a basket-like contour of the outer envelope surface 7. In this embodiment, no transition area is formed between the flat area 33 and the cylinder jacket-like area 34, but rather a "bend" that separates or connects these two areas. A similar design to that according to Fig.8 with a tangent-continuous transition region 24, similar to that of the embodiment according to the Fig. 1-5 , is conceivable. The fastening areas 18 at the inflow grille 1 according to Fig.8 are, viewed in the circumferential direction, arranged between two adjacent webs 35 of the outer row of the grid 1.

The webs 5a and 5b shown as examples have a large undercut area 17 with respect to a demolding direction parallel to the axis. Due to this large undercut area, demolding from a simple open-close injection molding tool parallel to the axis direction is not conceivable. Demolding is conceivable with slides that demold radially outwards in a star shape, which form the part of the grid 1 corresponding to the cylinder jacket-like part 34.

In Fig.9 the inlet grille 1 is according to Fig.8 shown in perspective view from behind (seen from the downstream side). The basket-like contour of the inner envelope surface 8 is clearly visible.

In Fig.10 the inlet grille 1 is in accordance with Fig.8 and 9 shown in axial plan view from the front (seen from the inflow side). Four identical cells 26 of the four-segmentation are shown as examples.

In Fig. 11 the inlet grille 1 is in accordance with Fig. 8 to 10 shown in a side view and in section on a plane through the axis. In this grille 1, the diameter D (20) of the grille 1 and the diameter DE (21) of the flat or level area 33 correspond, since no transition area is formed. The axial height H (22) of the grille 1 is slightly greater than the axial height HZ (23) of the cylindrical part, since the fastening areas 18 protrude axially to the right (towards the screw-on plane) beyond the grille. This means that in the assembled state, away from the fastening areas, there is a small distance between the nozzle 2 or the nozzle plate 32 and the grille 1 or the webs 35 of the outer row. This distance provides space, for example, for screw heads of screws that connect the nozzle 2 and the nozzle plate 32, or space for pressure tapping devices in the radius of the inlet nozzle 2. A similar design, according to which space is created between at least some outer grid webs 35 or also an outer connecting ring 25 and the nozzle 2 or the nozzle plate 32, is also possible for embodiments with unstructured grids similar to the Fig.1 until 7 and 12 until 16 conceivable. It is also conceivable in embodiments with unstructured grids that no transition areas are formed between the cylinder jacket-shaped area 34 and the flat or level area 33 of the inflow grid, but rather that they meet at a bend.

In Fig. 12 another embodiment of an inflow grille 1 according to the invention is shown in a side view and in section on a plane through the axis. The webs 5 in the exemplary embodiment are partially curved when viewed in section. This allows an even better adaptation of the grille 1 or the webs 5 to the inflow. In addition, advantages in terms of demoldability can be achieved with fixed, flow-favorable surface angles of the webs 5 on the inflow side (outer envelope surface 7). Furthermore, with the help of curved webs 5, a targeted, low-loss deflection of the inflow can be achieved if required. Any curvature (direction, amount) is conceivable. Curved webs 5 can also be axially aligned webs at the same time. For example, webs 35 of the outer row in particular can also be curved and axially aligned in this way.

Fig. 13 shows a further embodiment of an inflow grille 1 according to the invention in a perspective view from the front (from the inflow side). The grille 1 is constructed in an unstructured manner, so that in the majority of cases 3 webs 5 meet at the branching areas 15. An outer connecting ring 25 is formed, via which the webs 35 of the outer row are connected to one another. The connections 27 of the outer webs 35 to the connecting ring 27 are designed as rounded areas with relatively large rounding radii in extension of the webs themselves. The connections 27 advantageously extend in the radial direction over a large part of the radial extent of the connecting ring 25 (over more than half of this area). Four fastening areas 18 are integrated into the course of the connecting ring 25. The outer webs 35b, which are located approximately centrally on the fastening areas 18 in the circumferential direction, are reduced in external diameter in order to gain access to the screw connection of the inflow grille to the fastening areas 18. These outer webs 35b, which are reduced in external diameter, are advantageously extended inwards in diameter in order to have the necessary stability and the necessary cross-section for the injection molding process (see also the web 35b of the outer row in the area of a fastening area 18 in Fig. 16 ).

In the embodiment according to Fig. 13 a closed, central injection area 28 is formed. During plastic injection molding, the liquid plastic is injected centrally into this injection area 28 and is then distributed over this disk-like area into the webs 5. In this embodiment, the innermost webs 5 have an inner end 31 at which they are connected to the central injection area 28.

In Fig. 14 the inlet grille 1 is according to Fig. 13 shown in an axial plan view from the front (seen from the inflow side). This embodiment is designed to be completely free of undercuts with regard to demoulding in the axial direction. This makes tool production significantly easier and guarantees a reliable injection moulding process with short cycle times. Two webs 5a and 5b are shown as an example, the position of which is coordinated with one another in such a way that they do not overlap one another, seen in this axial plan view. To achieve this, A close interaction of the course of the envelope surfaces 7 and 8, the choice of the web depths t (9), the position and the alignment of the webs must be observed, taking into account compliance with the contact protection regulations.

In order to avoid undercut areas close to branching areas 15, the use of axially aligned webs 29 prevents two axially non-aligned webs 30 from meeting at a branching area 15, the wall normal vectors of which, aligned in the same cell 6, have x components (axis-parallel components) with different signs. As a result, in a branching area 15 in the exemplary embodiment, two axially non-aligned webs 30 often meet one axially aligned web 29, or three axially aligned webs 29. Other combinations occur less frequently. Axially aligned webs 29 are advantageously designed with draft angles in order to facilitate their demolding from an injection mold. In an injection mold, both sides of an axially aligned web are formed by the same tool part. The property "axially aligned" applies strictly speaking to a middle surface between the two sides of an axially aligned web 29.

In order to design a grille that is completely free of undercuts, it may be necessary to accept limitations in terms of acoustics and efficiency. Depending on the circumstances, it may also make sense to accept minor undercuts that can then still be demolded using a simple tool (forced demolding, rotary movement of tool parts, mapping of component contour areas on ejectors, etc.).

In the exemplary embodiment, in a radially inner area, approximately from a certain limit radius, all webs 5 are designed as axially aligned webs 29. As a result, the tool can be designed in such a way that in the corresponding inner cells 6 with exclusively or predominantly axially aligned webs 29, no tool parting line runs diagonally through the cells, but the complete contour of the cells can be introduced into a tool part. This further facilitates tool production. Due to the axial inflow In the inner area close to the axis, this can be easily achieved without any major loss of efficiency or acoustics.

The embodiment according to Figure 14 is made up of 12 identical segments, whereby the 12-fold rotational symmetry is locally interrupted by only 4 fastening areas 18. The number of different cells 6 is significantly reduced by segmentation with a high number of segments. In the exemplary embodiment, the inflow grille 1 has a total of 312 cells 6, but due to the segmentation there are only 26 differently designed cells 6. Embodiments with 8 segments are also particularly advantageous.

When forming four fastening areas 18, the number of segments is advantageously a multiple of 4. Segmentation can also be used to produce an inflow grille 1 according to the invention in several parts, in particular in the case of larger outer diameters.

Fig. 15 shows the embodiment according to Fig. 13 and 14 in a side view. The connection areas 27 of the outer webs 35 to the outer connecting ring 25 can be clearly seen. The connection area 27, which is designed here as a rounded area, can also be designed in a different way, for example as a chamfer.

In Fig. 16 is the embodiment according to Fig. 13 to 15 shown in a side view and in section on a plane through the axis. The exemplary webs 5a and 5b do not overlap when viewed in the axial direction. Furthermore, the connecting ring 25 does not overlap the web 5a when viewed in the axial direction. All of this is advantageous for a simple design of the injection molding tool, since undercuts between the webs 5a and 5b and the connecting ring 25 are avoided with regard to demolding parallel to the axial direction. The webs 35b of the outer row, which are located in the area of the fastening areas 18, are adapted to the screws with which the inlet grille 1 is screwed to an inlet nozzle 2 or to a nozzle plate 32, and their outer diameter is reduced for better accessibility. In order to have a web depth t that is favorable for the strength and the injection molding process, these webs 35b are also at least slightly offset inwards in diameter.

The central injection area 28 can be clearly seen in the section. In the injection molding process, the liquid plastic injected centrally in this area can be distributed well over the inner ends 31 onto the webs 5. The inner ends 31 are advantageously rounded with the central injection area 28 or provided with a chamfer.

Fig. 17 shows an example of a fan with an inlet grille 1, a nozzle 2 which is attached to a nozzle plate 32, and a fan impeller 3 which is driven by a schematically shown motor. During operation, the air first flows through the inlet grille 1 into the inlet nozzle 2 before it experiences a total pressure increase as it flows through the rotating impeller 3 of the fan. Turbulence in the inflow causes increased noise in the fan. An inlet grille 1 according to the invention evens out the inflow and thus reduces the noise. Depending on the embodiment, the inlet grille 1 also takes on the function of a suction-side contact guard. The pressure loss which occurs when the air flows through the grille 1 is minimized by the advantageous design according to the invention. A diagonal fan 3 is shown in the exemplary embodiment. The inlet grille 1 can just as easily be used with a radial or axial fan.

With regard to further advantageous embodiments of the teaching according to the invention, reference is made to the general part of the description and to the appended claims in order to avoid repetition.

Finally, it should be expressly pointed out that the exemplary embodiments of the teaching according to the invention described above serve only to explain the claimed teaching, but do not restrict it to the exemplary embodiments. The invention is limited by the appended claims.

List of reference symbols

1

Inflow grille

2

Inlet nozzle

3

Fan impeller

4

Motor

5, 5a, 5b

web

6

Grid cell, flow channel

7

outer, inflow-side envelope

7a

outer, inflow-side face of the webs

8

inner envelope

8a

inner, outflow-side face of the webs

9

Bridge depth t

10

Web thickness d

11

Bridge length I

12

Cell width w, insphere radius

13

neutral fiber of a bridge

14

outer end of a web, edge area

15

Branching area of webs

16

central branching point of bridges

17

Undercut area

18

Mounting area

19

Cell of the outer row

20

Diameter D of the grid

21

Diameter DE of the flat or level grid part

22

axial height H of the grid

23

axial height HZ of the cylinder jacket-like part

24

Transition area of the envelope

25

outer connecting ring

26

identical cells of a segmentation

27

Connection of the connecting ring

28

Closed, central injection area

29

axially aligned web

30,30a

axially non-aligned web

31

inner end of a web (edge area)

32

Nozzle plate

33

flat or level area of the inlet grille

34

Cylinder shell-like area of the inflow grille

35

Bridge of the outer row

35b

Web of the outer row in the area of a fastening area 18

Claims (10)

1. Axial, radial or diagonal fan, having an impeller and a preliminary guide device in the flow path in front of the inlet region of an inlet nozzle, wherein the preliminary guide device is in the form of an inflow grid (1) with planar webs (5), wherein the webs (5) form a large number of cells (6) with grid-cell-like flow channels, wherein the cells (6) at least partially have a honeycomb-like cross-section, wherein the cells (6) as a result of different cell contours are formed by regular and/or irregular squares and/or pentagons and/or hexagons,
   characterised in that the webs comprise axially aligned webs and axially non-aligned webs, wherein in at least one branch region two axially non-aligned webs meet on at least one axially aligned web.
2. Fan (axial, radial or diagonal fan) according to claim 1, characterised in that the cells (6) in the region close to the axis are smaller than those in the region remote from the axis.
3. Axial, radial or diagonal fan having an impeller and a preliminary guide device in the flow path in front of the impeller, preferably in front of the inlet region of an inlet nozzle, wherein the preliminary guide device is in the form of an inflow grid (1) having planar webs (5), wherein the webs (5) form a large number of grid-cell-like flow channels (6), and wherein the inflow grid has a basket-like contour (outer and/or inner enveloping surface) which has a cylinder-covering-like outer region (34) and a planar region (33) close to the axis,
   characterised in that the webs comprise axially aligned webs and axially non-aligned webs, wherein in at least one branch region two axially non-aligned webs meet on at least one axially aligned web.
4. Fan according to claims 1 to 3, characterised in that a region free from webs (5) is formed at the centre of the inflow grid (1), that is to say, without flow channels (6).
5. Fan according to any one of claims 1 to 4, characterised in that the webs (5) have a web thickness in the range from 0.25 mm to 2 mm.
6. Fan according to any one of claims 1 to 5, characterised in that a region close to the axis of the contour extends in a level or very planar manner, substantially orthogonally with respect to the centre axis.
7. Fan according to any one of claims 1 to 6, characterised in that an outer edge region of the inner contour extends substantially parallel with the centre axis, approximately on a notional cylinder covering.
8. Fan according to any one of claims 1 to 7, characterised in that the inflow grid (1) has in an outer edge region securing means which are preferably integral with some of the webs (5) and which are used for positive-locking and/or non-positive-locking securing on the inlet nozzle (2) or the nozzle plate (32) of the fan.
9. Fan according to any one of claims 1 to 8, characterised in that there is formed on the edge region of the inflow grid (1) a stabilisation ring which preferably comprises securing means which are used for positive-locking and/or non-positive-locking securing on the inlet nozzle (2) or the nozzle plate (32) of the fan.
10. Inflow grid having features according to any one of claims 1 to 9.

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