RU2786681C2 - Fan and inlet grid for fan - Google Patents

Abstract

FIELD: ventilation.

SUBSTANCE: axial, radial, or diagonal fan includes a working wheel and an input guiding device on a flow path in front of the working wheel, preferably in front of an input area of an input nozzle. In this case, the input guiding device is made in the form of inlet grid (1) having flat ribs (5), wherein these ribs (5) form a set of flow channels (6) in the form of grid cells, while each rib (5) is quite predominantly distributed between preferably two branches (15) or between branch (15) and edge area (14, 31), while three ribs (5) quite predominantly occur in preferably each branch (15). Alternatively, flow channels (6) of inlet grid (1) have a cellular cross-section, and/or inlet grid (1) forms a basket contour relatively to an outer and/or inner bending circumflex surface. A corresponding inlet grid is proposed.

EFFECT: obtainment of a fan and an inlet grid for a fan.

10 cl, 18 dwg

Description

The present invention relates to a fan (axial, radial or diagonal fan) having an impeller and an inlet guiding device in the flow path in front of the impeller, preferably in front of the inlet region of the inlet nozzle, the inlet guiding device is made in the form of an inlet grille having flat ribs, and while the ribs form a plurality of flow channels in the form of lattice cells. In addition, the invention relates to a special inlet guiding device, which is made in the form of an inlet grate having flat ribs.

A generic fan having an inlet (front) guiding device located on the inflow side is known, for example, from WO 03/054395 A1. The inlet guiding device provided there primarily serves to equalize the flow, in particular also to reduce noise. Known input guide device creates a preliminary twist in the direction of rotation of the impeller. It is significant that acoustic improvements are usually accompanied by a detriment to air performance and efficiency. The inlet guide provided there is, moreover, very laborious to manufacture.

From practice, so-called inlet guide wheels are also known, which serve to favor the efficiency and/or air capacity. However, these inlet guide wheels lead to acoustic disadvantages and are complex in design and installation in related fan products. As a rule, they are mounted in front of the fan impellers in a cylindrical structural space having a diameter of approximately the fan impeller, and at the same time they have a slightly larger flow area compared to the fan. The air velocities in the region of these inlet guide wheels are therefore relatively high, which in particular creates acoustic disadvantages.

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

Fans often react to a disturbed supply with increased noise. In many fan applications, such as controlled ventilation of living spaces (KWL), due to the generally compact requirements, disturbed airflow conditions inevitably occur. The resulting noise, which often has large tonal components, is typically low frequency. Particularly with ventilation devices, the reduction of this low-frequency noise is mandatory.

It is also already known to significantly reduce noise in case of disturbed inflow by means of so-called flow conditioners. However, such flow conditioners cause significant pressure losses and, in addition, require a large structural space. Therefore, the present invention is based on the task to design and improve the fan in such a way that noise reduction occurs when the inflow is disturbed. The fan must be designed compactly and have only extremely low pressure losses. In addition, an inlet (front) guiding device, in particular an inlet grid or an inlet (front) guide grid, which meets the above requirements and which can be produced with economical tool costs in a plastic injection molding process, should be proposed. It should have a stable shape and preferably be able to perform the function of a contact guard located on the supply side.

The higher task in relation to the fan according to the invention is solved with the help of alternative combinations of features of paragraphs 1, 2 and 3 of the claims. With regard to the inlet grill according to the invention, the above problem is solved by means of the features of claim 12, which refers to the fan claims.

Within the scope of the first variant according to claim 1, the ribs extend predominantly between preferably two ramifications or between each ramification in the edge region. Preferably, three edges meet in each branch. With the help of these features, very special flow channels in the form of grid cells are obtained, which are designed to reduce noise during disturbed inflow.

Claim 2 of the claims solves the above problem in such a way that the flow channels at least partially have a honeycomb cross section. This design also achieves very good stability.

Claim 3 claims another alternative, according to which the intake grille has a basket contour, this embodiment referring to the outer and/or inner envelope of the intake grille.

The same applies to the design of the inlet grille itself, which is defined by claim 12 with reference to the fan claims.

These claims are based on the principle idea to provide an inlet grate or an inlet grate in front of the fan inlet nozzle in order to reduce the noise generated during fan operation in case of disturbed inflow. The inlet grate is defined by flat ribs, these ribs being arranged relative to each other in such a way that flow channels are formed in the form of grid cells. Thanks to such an ingenious combination of ribs, which form ramifications and nodal points, preferred geometries can be realized, for example in that the flow channels have a honeycomb cross section. The term "honeycomb" is to be understood in its widest sense, so that it should also include all polygons, for example, lattice cells having a 4-gonal, 5-gonal or 6-gonal, respectively, polygonal cross section.

According to the above-described flow channels in the form of grate cells, it is also preferable that the inlet grate has a basket contour, and this contour can refer to both the outer and inner envelope surface of the inlet grate.

An inlet grate of the above type satisfies the radial inflow in the region near the nozzle plate. The supply channels preferably contribute to low pressure losses. The basket-shaped outer contour is also advantageous for demoulding in the injection molding technology used in particular for plastic parts. Furthermore, compact gratings having suitable properties can be produced.

A basket-shaped outer contour is very particularly preferred when it is continuous and curved. The lattice fins should be made as thin as possible, for example with a rib thickness ranging from 0.25 mm to 1 mm. In the direction of the flow, they must have a depth of at least 5 mm (hence the term "flat rib" chosen in the claims).

Also preferably, the lattice ribs form an unstructured lattice, in which the honeycomb cells of the lattice are combined with each other. As already mentioned above, the lattice cells can be polygonal and combined with each other, respectively, with each other. In this way, a minimum obstruction by the grille ribs can be achieved, in particular when a certain maximum grille clearance is required due to the necessary noise reduction or touch protection aspects, which leads to low pressure and efficiency losses.

The inlet grille also preferably extends over the entire region up to an imaginary continuation of the fan axis, ie has no opening or has a not particularly large opening in the inner region. Such a middle opening is not necessary in view of the theory proposed by the invention, it should even be avoided, since the inlet grill additionally provides a touch protection. In addition, it was found that the middle hole hinders the minimization of noise and the stability of the grating.

In any case, the special design of the inlet grate is of particular advantage, not only in relation to flow channels in the form of grate cells, but also in relation to a continuous and curved outer contour. With honeycomb elements having 4, 5 or 6 corners, unstructured gratings can be realized, while varying grating gaps are realized throughout the inlet grating, depending on the need.

The inlet grill according to the invention is used in an axial, radial or diagonal fan and is designed in accordance with the above considerations.

So, there are various possibilities to carry out and improve the theory of the present invention in an advantageous manner. To this end, on the one hand, reference should be made to the claims following claim 1 and, on the other hand, to the following explanation of preferred embodiments of the inlet grill according to the invention with the help of drawings. In connection with the explanation of the preferred embodiments of the invention with the help of the drawings, general preferred embodiments and improvements of this theory are also explained. The drawings show:

1: in perspective view, viewed from the inflow side, one embodiment of the inlet grill according to the invention;

Fig. 1a: in a perspective view, a schematic, detailed view of a cell consisting of ribs according to Fig. 1, with the characteristic dimensions of the ribs and cells indicated;

Fig. 2: in perspective view, as seen from the outflow side, the inlet grill of Fig. 1;

Fig. 3: in axial plan view, as seen from the inflow side, the inlet grate of Figs. 1 and 2;

4: in axial plan view, as viewed from the outflow side, the inlet grille of FIGS. 1-3;

Fig.5: in a side view and in a section along the plane through the axis of the inlet grate in accordance with Fig.1-4, while indicating the characteristic dimensions of the inlet grate;

Fig. 6: in perspective view from the inflow side, another exemplary embodiment of the inlet grate according to the invention;

Fig. 7: in axial plan view, viewed from the outflow side, the inlet grille of Fig. 6;

Fig.8: in perspective view, when viewed from the inflow side, another embodiment of the inlet grate;

Fig. 9: in perspective view, as viewed from the outflow side, the inlet grill of Fig. 8;

Fig. 10: in axial plan view, viewed from the inflow side, the inlet grate of Figs. 8 and 9;

Fig.11: in a side view and in a section along the plane through the axis of the inlet grate in accordance with Fig.8-10, while indicating the characteristic dimensions of the inlet grate;

Fig.12: in a side view and in a section along the plane through the axis, another example of the inlet grill according to the invention, having curved ribs;

Fig. 13: in perspective view, as seen from the inflow side, another embodiment of an inlet grate having a central, closed molded area;

Fig. 14: in axial plan view, as viewed from the outflow side, the inlet grill of Fig. 13;

Fig.15: in side view of the inlet grille in accordance with Fig.13 and 14;

Fig.16: in side view and in section along the plane through the axis of the inlet grill in accordance with Fig.13-15;

Fig. 17: In a schematic perspective view, viewed from the inflow side and in a plane cross-section through the axis, a fan having a motor, an impeller, an inlet nozzle, a nozzle plate and an inlet grate in accordance with Figs. 13-16.

1 shows one embodiment of the inlet grille 1 in a front perspective view, i. e. when viewed from the tributary. The inlet grille 1, as shown in Fig. 17, is preferably mounted in front of the inlet nozzle 2 of the fan so that its axis approximately coincides with the axis of rotation of the fan. During operation of the fan, the air first flows through the inlet grille 1 into the inlet nozzle 2 before it experiences an increase in total pressure as it flows through the fan impeller 3, which is driven by the motor 4. The inlet grille 1 evens out the incoming air, thereby reducing the noise generated in the impeller.

The inlet grate 1 consists of a plurality of ribs 5 which define cells 6 of the grate. Through the cells 6 of the grid during operation of the fan, a flow is carried out, that is, they form flow channels. The flowing air has a lower speed in the area in front of the inlet nozzle 2 than inside the inlet nozzle 2, since the flow area for the air mass flow blown by the fan in the area in front of the inlet nozzle 2 is larger than in the inlet nozzle 2. The inlet grate 1 is used in such an area rather lower flow rates, ie. the flow velocity at the inlet grate 1 is lower than the flow velocity at the inlet nozzle 2. This keeps the hydraulic losses and noise generation at the inlet grate 1 low.

Since, however, the inflow in the region upstream of the inlet nozzle 2 is not even, or predominantly not parallel to the axis, it is also a great advantage that the contour of the inlet grate 1 is not completely even. This contour can, for example, be described by an outer envelope surface 7 and/or inner envelope surface 8 (figure 2) of the inlet grille 1. These envelope surfaces 7, 8 are defined by a combination of end surfaces 7a, respectively, 8a located on the inflow side, respectively, located on the outflow side, ribs 5 (see fig. 1a), supplemented imaginary continuous or curved-continuous endings in the area of the flow channels 6.

In Fig. 1a, a detailed, enlarged view shows the region of the intake grille 1 of Fig. 1. The ribs 5, when viewed in the direction of the flow, have a significant depth t (9), preferably about 6-20 mm. Because of this, ribs 5 are also called "flat" ribs. Cell 6 of the grating is also largely characterized by the gap w (12) of the cell, for example, a certain radius of the largest inscribed ball of cell 6. In order to achieve good acoustic values, a small gap w (12) of the grating is preferable, for example, the value of w (12) is not more than than two to three times the depth t (12) of the rib for the predominant number of cells 6 of the intake grille 1. The intake grille 1 in the exemplary embodiment according to FIG. must fulfill the requirements for the gap w (12) of the cell, depending on the shape of the cell and the distance from cell 6 to the rotating part of the fan. Thus, the gap size w (12) of the cell is additionally limited from above.

For low pressure loss and efficiency, it is preferable to block the flow area as low as possible by the grid ribs 5 . This can be achieved by thin fins (thickness d (10) of the fin preferably predominantly ˂= 2 mm [˂= 1 mm] and/or by minimizing the overall length of the fin (the sum of all lengths l (11) of the fins of the inlet grille (1) The lengths l of the fins are determined from the neutral fibers 13, preferably from the outer or inner envelope surface 7, respectively 8) "Unstructured" lattice structure having honeycomb cells 6 as in this embodiment, under the described conditions of maximum clearance w (12) sieves may be highly preferred for the required total fin length.

Fig. 2 shows the inlet grate 1 according to Fig. 1 in perspective view as viewed from the outflow side. The inlet grate 1 has on the outside attachment areas 18 which serve to fasten the inlet grate 1 to the inlet nozzle 2 or nozzle plate 32 (FIG. 17). Various possibilities are available for the execution of the fastening areas 18 . Possible fasteners are screws, rivets, snap hooks, bayonet closures, adhesives, stoppers, textile fasteners or others. In this exemplary embodiment, four fastening areas 18 are each provided with a screw hole.

In the view in accordance with figure 2, the basket contour of the inner envelope surface 8 of the inlet grille 1 is clearly visible. On the outer perimeter, this contour extends somewhat further, preferably more than 10 mm or more than 8% of the outer diameter D (20) ( 5) approximately parallel to an imaginary median axis approximately along some cylinder side surface (cylinder side-like region 34). In this cylinder-like region 34, cells 19 of the outer row lie, of which every two adjacent ones are separated from each other by an edge 35 of the outer row. Cells 19 of the outer row are rather oblong in shape. In order to provide protection from touch and to achieve acoustic improvements, the gaps w of the cells (the inscribed ball radii, in the cells 19 of the outer row are essentially determined by the distance between each two adjacent ribs 35 of the outer row) of these cells are rather smaller compared to the inscribed ball radii of the other cells 6. In the area close to the axis, the contour runs evenly or gently, approximately orthogonally to the axis (shallow area 33). The transition from the flat region 33 to the cylinder-like region 34 occurs via a short transition region 24, which in this embodiment runs curved. In this exemplary embodiment, the outer envelope 7 and the inner envelope 8 run approximately parallel. The division into regions 33, 34, 24 can be carried out along the outer and/or inner envelope surface 7, respectively, 8.

Figure 3 shows the inlet grille 1 according to Figures 1 and 2 in axial plan view from the front (when viewed from the inflow side). Such an inlet grille 1 is preferably produced by injection molding of plastics. It is also preferable to select the viewing direction of Fig. 3 also as the demoulding direction for the injection molding tool in order to reduce the complexity of the tool. Then, during the demoulding process, one part of the tool moves relative to the inlet grate 1 in the direction of the observer, preferably the side of the tool nozzle, and the other part of the tool away from the observer. The injection molding tool preferably does not have any other gates in order to be able to be easily manufactured.

The fastening areas 18 are made in conjunction with the lattice ribs 5 in such a way that they can be removed from the mold of the injection molding tool without undercuts in the direction of the gate parallel to the axis (corresponding to the direction of view in this image). It can be seen that the grille ribs 5 are not partly oriented parallel to the central axis (= viewing direction), but, on the contrary, are optimally adapted in their orientation to the inflow conditions. The fins may preferably also have a curvature in order to optimally guide the flow. Rib 29 is noted as an example, which is an axially aligned rib, i.e. it is oriented parallel to the axis (direction of view and gate), which makes it easier to remove it from the mold. The axially aligned ribs 29 are preferably provided with a demoulding bevel. However, there are also ribs 30, 30a that are not axially aligned, since all ribs 5 are optimally adapted to the flow directions as far as possible. The two radially outer rows of grille ribs 5, which extend approximately in the circumferential direction, extend in the transition region 24 of the envelope surfaces 7 or 8 and are matched to each other so that only small or no undercut regions occur, i.e. if viewed in the axial direction, they do not hide each other or only slightly hide each other. In the exemplary embodiment shown, there is, by way of example, a small undercut region 17 in combination with the rib 5a of the radially outer row of ribs 5 and the rib 5b of the second row of ribs 5, since these two ribs have a small area of overlap in the viewing direction. By choosing a suitable, rather resilient material, small undercuts can be realized and still demoulded with a simple axially opening and closing tool. As a result, a particularly hydrodynamically optimal contour can be realized simply and economically. In addition, there is a small undercut region in the ramification region 15 between both axially misaligned ribs 30 and 30a because the x component of their surface normal vectors has a different sign. And this slight undercut, when the right material is chosen, can be removed from the mold with a simple opening and closing tool.

In this exemplary embodiment, the cells in the region close to the axis are smaller than the cells in the region remote from the axis. The size of the cells, respectively the gap w of the cells (12, see FIG. 2) is always optimized in terms of the requirements for fulfilling the touch protection regulations and for the acoustic improvements achieved, respectively, for flow equalization. The distribution of cells is optimized using a special algorithm. There are (when viewed on one of the envelope surfaces 7 or 8) a variety of cell contours, in particular, but not exclusively, regular and irregular 4-6-gons. Approximately each cell (viewed on the envelope surface 7 or 8) describes some region of points, which are the points that lie closest to the imaginary center point (on the envelope surface) compared to the imaginary center points of all other cells. Consequently, the design of the lattice 1 is also different in that exactly 3 ribs 5 occur in the predominant number of branching regions 15, 4 ribs 5 occur in a much smaller number of branching regions. any of their neighboring cells, which arise due to the effect of "crossing the outer cells by the frame."

4 shows the inlet grill 1 of FIGS. 1-3 in axial rear plan view (when viewed from the outflow side). The axially aligned ribs 35 of the outer row have a free end 14. As a result, they can be removed from the mold by the gate of the tool, which, when opened, moves in the direction of the outflow side (in the direction of the observer). The fact that the ends 14 of the outer ribs 35 are not connected is a disadvantage in terms of strength and dimensional stability, but can be compensated for by high quality material or large wall thicknesses d (10).

The inlet grille 1 in this embodiment is made up of four identical segments. This is a significant advantage, above all, in the design of the structural element and the tool required for the manufacture, since the number of differently made grid cells 6 is reduced by a factor of 4 (factor=number of segments). The flow pattern resulting from this segmentation is independent of the orientation (quadrant) of the inlet grille 1 during installation. Another number of segments is also possible. The segments may differ slightly from each other, for example, in the area of the fasteners, if their number does not correspond to the number of segments, or in the inner region close to the axis, in which segmenting under certain circumstances may be more difficult. Particularly for large outer diameters, segmenting can be advantageously used so that the inlet grilles 1 are made up of several injection molded segments, for example by clamping, locking, screwing, gluing, by attaching to the nozzle plate or the like. With this composite technology, it is also possible, in addition to actually identical segments, to realize a separate, different central part, which then, however, requires its own injection molding tool. However, this central part can have a simple shape, in particular be even, respectively, sloping.

In the shown embodiment, in the center, on the axis, is the central point 16 of the ramification of the 4 (=number of segments in this embodiment) ribs 5.

Figure 5 shows the inlet grille 1 in accordance with figures 1-4 in side view and in section along the plane through the axis. We can clearly distinguish the course of the basket contour located on the inflow side, as well as the envelope surfaces 7 located on the outflow side, respectively, 8. The outer envelope surface 7 has an outer diameter D (20), which is also called the diameter D (20) of the inlet grille 1, and here the diameter of the fastening regions 18 is not taken into account. The outer envelope 7 and the inner envelope 8 run approximately parallel to each other in this embodiment. The distance between the envelope surfaces 7 and 8 is preferably between 6 mm and 18 mm, or approximately 3%-10% of the diameter D (20) of the inlet grille 1. In the regions above and below, near the screwing plane, some part of the contour always runs approximately parallel to the axis ( similar to the side surface of the cylinder part 34). A continuous and curved transition is made in the transition area 24 to the flat area 33, in this image on the right (inflow side). The transition region 24 has a small extent in the radial direction, less than 12.5% of the outer diameter D (20). The shallow area 33 has a diameter DE (21) which is preferably relatively large and is at least 75% of the outer diameter D (20). The inlet grille 1 has an axial structural height H (22), while the area similar to the side surface of the cylinder on the outer envelope surface 7 has an axial extent HZ (23). HZ (23) is preferably greater than 6% of the diameter D (20).

The basket contour of the inlet grille 1, respectively, its envelope surfaces 7, 8 are well adapted in terms of flow conditions. In the region 34, which is similar to the cylinder flank, air flowing radially from the nozzle plate 32 is to be expected, which, due to the shape of the lattice 1 in this region 34, which is similar to the cylinder flank, can pass through it approximately transversely to the envelope surfaces 7, 8 along a short path. and at the same time with small hydraulic losses. In the gently sloping, correspondingly flat area 33, a rather axial inflow is to be expected, which then also flows through the grate 1 along a short path across to the envelope surfaces 7, 8. Due to the compactly designed, short transition area 24, a small structural height H (22 ), which is preferable for the small footprint of the inlet grille 1. Preferably, the axial structural height H (22) is not greater than 25% of D (20).

The purposeful orientation of the ribs is also clearly visible, which do not always run exactly perpendicular to the envelope surfaces, but, partly deviating noticeably from them, are optimally adapted to the exact direction of the inflow. In this exemplary embodiment, the ribs 5 are not curved in the direction of the flow. But it is quite possible in other embodiments. At the radially outer ribs 35, the outer ends 14 are open, i.e. not connected to each other (except in the fastening areas 18).

FIG. 6 shows another embodiment of the inlet grille 1 in a front perspective view (when viewed from the inflow side). In contrast to the exemplary embodiment in fg.1-5, the outer ends 14 of the ribs 35 of the outer row are connected by an outer connecting ring 25. This increases the stability of the shape of the outer ribs 35, which may be preferable from the point of view of fulfilling the requirements set for protection against touch, in particular when softer or more resilient materials are used. Also, the outer connecting ring 25 may be preferred for the nature of the filling of the injection molding tool. The connecting ring 25 is connected to the ribs 35 by means of an attachment 27. This attachment is made as a continuation area of the outer ribs 35 in the form of a rounding having a large rounding radius ˃ 3 mm. The fastening areas 18 are integrated into the connecting ring 25.

In this exemplary embodiment, the connecting ring 25 lies in a plane which is the screwing plane to the nozzle 2 or to the nozzle plate 32 . In other preferred embodiments, the connection ring 25 may extend outside the fastening areas 35 with an axial shift relative to the screwing plane. This creates a space between the nozzle 2 or the nozzle plate 32 and the connection ring 25 in the mounted state. pressure tapping devices. If the connecting ring extends in some areas with an axial shift relative to the screwing plane, some or all of the ribs 35 of the outer row may protrude beyond it in the direction of the nozzle 2 or the nozzle plate 32 or, when viewed in the axial direction, end at the connecting rib 25. Other ribs can also be located in the area between the connecting rib and the screwing plane. In other embodiments, it is also possible for the connecting ring 25 to be interrupted in certain areas, and there are separate outer ribs 35 having open outer ends 14. These outer ribs 35, having open outer ends 14, can also be shortened so that the outer ends 14 lay at a distance from the screwing plane. And this can serve to create, in the mounted state, between the screwing plane and the inlet grille 1 space for screw heads, pressure taps or the like.

FIG. 7 shows the inlet grille 1 according to FIG. 6 in an axial rear plan view (when viewed from the outflow side). It can be seen in this image, in particular, that the connecting ring 25 lies radially completely outside all the ribs 5, with the exception of the axially aligned ribs 35 of the outer row with their attachments 27 to the connecting ring 25. closable injection molding tool. Figure 7 clearly shows four identical cells 26 of the lattice 1, consisting of four identical segments. Since the number of cells that differ from one another is greatly reduced by such segmentation, the costs of constructing the grate 1 and, above all, the proper injection molding tool, are reduced.

Fig. 8 shows the inlet grille 1 in a front perspective view (when viewed from the inflow side). The cells 6 as well as the ribs 5 are arranged there neither in a honeycomb nor in an unstructured manner, on the contrary, ribs 5 extending radially and circumferentially are provided. The four radially extending ribs 5 meet in the central axial region at the central junction 16 . The number of ribs 5 that occur in each bifurcation region 15 is predominantly 4. The intake grille 1 has a basket-shaped outer envelope surface 7. break" which separates, respectively, connects these two areas. An implementation similar to that of FIG. 8 is possible, having a tangential continuous transition region 24 similar to the transition region of the embodiment according to FIGS. 1-5. Attachment areas 18 at the inlet grille 1 according to FIG. 8, when viewed in the circumferential direction, are located between each two adjacent ribs 35 of the outer row of the grille 1.

The exemplary ribs 5a and 5b have a large undercut region 17 with respect to the demoulding direction parallel to the axis. Because of this large undercut area, demoulding a simple opening and closing injection molding tool parallel to the axial direction is not possible. Demoulding is possible with star-shaped, radially outward demoulding gates, which form a part of the lattice 1, which is in response to a similar side surface of the cylinder of part 34.

In Fig. 9, the inlet grate 1 according to Fig. 8 is shown in a rear perspective view (when viewed from the outflow side). We can clearly distinguish the basket contour of the inner envelope surface 8.

Fig. 10 shows the inlet grate 1 according to Figs. 8 and 9 in axial plan view from the front (when viewed from the inflow side). Four identical quadrant segmentation cells 26 are clearly shown.

In Fig.11 shows the inlet grill 1 in accordance with Fig.8-10 in side view and in section along the plane through the axis. With this grating 1, the diameter D (20) of the grating 1 and the diameter DE (21) of the gently sloping, respectively, flat region 33 correspond to each other, since the transition region is not made. The axial structural 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 beyond the grille in the axial direction to the right (in the direction of the screwing plane). This means that in the mounted state, outside the attachment areas, there is a small distance between the nozzle 2 or the nozzle plate 32 and the grate 1 or the ribs 35 of the outer row. This distance gives, for example, space for the heads of the screws that connect the nozzle 2 and the nozzle plate 32, or space for pressure taps in the radius of the inlet nozzle 2. A similar design, in which there is space between at least some of the outer ribs 35 of the grid, respectively , also the outer connecting ring 25 and the nozzle 2, respectively, the nozzle plate 32, is also possible for embodiments having unstructured gratings, like figures 1-7 and 12-16. Also in embodiments having unstructured gratings, it is possible that between the region 34 shaped as a side surface of the cylinder and the gently sloping, respectively, flat region 33 of the inlet grate, transitional regions are not made, but, on the contrary, they are closed to each other at a break.

FIG. 12 shows another embodiment of the inlet grille 1 according to the invention in side view and in cross-section along a plane through the axis. Ribs 5 in this exemplary embodiment, when viewed in cross section, are partially curved. As a result, an even better adaptation of the grid 1 or the ribs 5 to the inflow can be achieved. In addition, the advantages of demoulding with fixed hydraulically favorable dihedral angles of the ribs 5 on the inflow side (outer envelope 7) can be achieved. Moreover, with the aid of the curved fins 5, if necessary, targeted, low-loss redirection of the inflow can be achieved. Any kind of curvature (in direction, magnitude) is possible. The curved ribs 5 can also be axially aligned ribs at the same time. Thus, for example, in particular also the ribs 35 of the outer row can be made curved and axially aligned.

FIG. 13 shows another embodiment of the inlet grille 1 according to the invention in a front perspective view (when viewed from the inflow side). The grid 1 is constructed in an unstructured manner, so that in the junction areas 15, 3 ribs 5 occur in the majority of cases. Attachments 27 of the outer ribs 35 to the connecting ring 27 are made in the form of roundings having relatively large radii of curvature, in continuation of the ribs themselves. Preferably, the attachments 27, when viewed in the radial direction, extend over a large part of the radial extent of the connecting ring 25 (more than half of this area). The four mounting areas 18 are integrated along the connection ring 25. The outer ribs 35b, which, when viewed in the circumferential direction, lie in the mounting areas 18 approximately in the middle, are reduced in outer diameter in order to gain access for screwing the intake grille beyond the mounting areas 18. Preferably these outer diameter reduced ribs 35b are extended inward to have the necessary stability and cross section for the injection molding process (see also outer row rib 35b near attachment area 18 in FIG. 16).

In the embodiment according to FIG. 13, a closed central molded area 28 is provided. In injection molding, liquid plastic is centrally injected into this molded area 28 and then distributed over this disc-shaped area into the ribs 5. The innermost ribs 5 have in this embodiment inner end 31 by which they are attached to the central molded area 28.

Fig. 14 shows the inlet grate 1 according to Fig. 13 in an axial front plan view (when viewed from the inflow side). This embodiment is completely free of undercuts with respect to demoulding in the axial direction. This decisively facilitates tool manufacturing and guarantees a reliable injection molding process with short cycle times. By way of example, two ribs 5a and 5b are shown, the position of which is mutually coordinated so that, when viewed from this axial plan view, they do not mutually overlap. In order to achieve this, it is necessary to take into account the close coordination of the course of the envelope surfaces 7 and 8, the choice of depths t (9) of the rib, the position and orientation of the ribs, taking into account the fulfillment of the requirements of protection against contact.

In order to avoid undercut regions near the branching regions 15, when using axially aligned ribs 29, two axially non-aligned ribs 30 are avoided in the same branching region 15, in which the normal vectors to the wall oriented to the same cell 6 have x-components (axis-parallel components) with different signs. As a result, 2 axially misaligned ribs 30 with one axially aligned rib 29, or three axially aligned ribs 29, often occur in one ramification area 15 in this embodiment. Other combinations occur less frequently. The axially aligned ribs 29 are preferably provided with demoulding bevels to facilitate their demoulding of the injection molding tool. In an injection molding tool, two sides of the same axially aligned rib are made from the same part of the tool. The property "axially aligned" refers, more specifically, to the median surface between the two sides of the axially aligned rib 29.

In order to make a grating completely free of undercuts, under certain circumstances, one must come to terms with limitations in acoustics and efficiency. Depending on these conditions, it may also be advisable to accept small undercuts, which can then, nevertheless, be demoulded with a simple tool (forced demolding, rotational movement of tool parts, reproduction of contour areas of a structural element on ejectors, etc.). .P.).

In this exemplary embodiment, in the radially inner region, approximately starting from a certain limiting radius, all the ribs 5 are made in the form of axially aligned ribs 29. As a result, the tool can be designed so that the respective inner cells 6 having exclusively or predominantly axially aligned ribs 29 , the parting line of the tool did not pass obliquely through the cells, and the entire contour of the cells could be entered into one part of the tool. This further facilitates tool manufacturing. Due to the axial inflow in the inner, close to the axis region, this is well realized without much damage to efficiency or acoustics.

The embodiment according to FIG. 14 consists of 12 identical segments, with the 12-fold rotational symmetry interrupted locally by only 4 fastening areas 18. The number of different cells 6 is noticeably reduced due to segmentation at a high number of segments. In this exemplary embodiment, the inlet grille 1 has a total of 312 cells 6 and, due to the segmentation, there are only 26 differently made cells 6. Embodiments with 8 segments are also particularly preferred.

When four fastening regions 18 are provided, the number of segments is preferably a multiple of 4. Segmentation can also be used to produce a compound inlet grille 1 according to the invention, in particular with large outer diameters.

FIG. 15 shows the embodiment according to FIGS. 13 and 14 in side view. The areas 27 of attachment of the outer ribs 35 to the outer connecting ring are clearly visible. The attachment area 27, which is here made in the form of a rounding, can also be made differently, for example, in the form of a bevel (chamfer).

Fig. 16 shows the embodiment according to Figs. 13-15 in side view and in cross-section along a plane through the axis. The clearly marked ribs 5a and 5b, when viewed in the axial direction, do not overlap. In addition, the connecting ring 25, when viewed in the axial direction, does not overlap the rib 5a. All this is advantageous for the simple execution of the injection molding tool, since there are no undercuts between the ribs 5a and 5b and the connecting ring 25 with respect to demolding parallel to the axial direction. The ribs 35b of the outer row, which are located near the fastening areas 18, for better accessibility to the screws with which the inlet grille 1 is screwed to the inlet nozzle 2 or to the nozzle plate 32, are adapted and reduced in their outer diameter. In order to have a rib depth t favorable there for strength and injection molding, these ribs 35b are also at least slightly shifted inwards.

The central molded region 28 is clearly visible in cross section. In the injection molding process, the liquid plastic injected centrally in this region can be well distributed beyond the inner ends 31 onto the ribs 5. In this case, the inner ends 31 are preferably rounded by the central molded area 28, respectively, provided with a chamfer.

Fig. 17 clearly shows a fan having an inlet grate 1, a nozzle 2 which is placed on a nozzle plate 32, and a fan wheel 3 which is driven by a schematically depicted motor. In operation, the air first flows through the inlet grille 1 into the inlet nozzle 2 before it experiences an increase in total pressure as it flows through the rotating impeller 3 of the fan. Turbulences in the inlet cause increased noise in the fan. The inlet grille 1 according to the invention evens out the inflow and thus reduces noise. Depending on the embodiment, the inlet grille 1 also functions as a touch protection located on the suction side. The pressure loss that occurs when air flows through the grate 1 is minimized by the preferred embodiment according to the invention. In this exemplary embodiment, a diagonal fan 3 is shown. The inlet grille 1 can be used just as well with a radial or axial fan.

With regard to other preferred embodiments of the theory proposed by the invention, in order to avoid repetition, we refer to the general part of the description, as well as to the attached claims.

Finally, it should be directly pointed out that the above-described embodiments of the idea proposed by the invention serve only to analyze the claimed idea, but do not limit it to these examples of implementation.

LIST OF REFERENCES

1 intake grille

2 Inlet nozzle

3 Fan impeller

4 Engine

5, 5a, 5b Rib

6 Grid cell, flow channel

7 Outer, inflow-side envelope

7a External, inflow side end face of fins

8 Inner envelope

8a Internal end face of the ribs on the outflow side

9 Depth t of the rib

10 Thickness d fin

11 Length l of the rib

12 Clearance w of the cell, radius of the inscribed sphere

13 Neutral fiber rib

14 Outer end of the rib, marginal area

15 Rib fork area

16 Central rib fork

17 Undercut area

18 Attachment area

19 Cell outer row

20 Grid diameter D

21 Diameter DE of the sloping, respectively, flat part of the grating

22 Axial height H of the grille

23 Axial height HZ of the part similar to the side surface of the cylinder

24 Envelope transition region

25 Outer connecting ring

26 Identical segmentation cells

27 Connecting the connecting ring

28 Closed, central molded area

29 Axially aligned rib

30, 30a Axially misaligned rib

31 Inner end of the rib (edge area)

32 Nozzle plate

33 Sloping, respectively, flat area of the intake grille

34 Intake grille area similar to cylinder side

35 Edge of the outer row

35b Edge of the outer row in the area 18 of the attachment.

Claims (10)

1. A fan having an impeller and an inlet guide device on the flow path in front of the inlet area of the inlet nozzle, while the inlet guide device is made in the form of an inlet grid (1) with flat ribs (5), moreover, these ribs (5) form a plurality of cells ( 6) with flow channels in the form of lattice cells, and the cells (6), at least partially, have a honeycomb cross-section, and the said cells (6) are formed by a regular or irregular quad due to different cell contours, and/or 5 -gon, and/or 6-gon. 2. The fan according to claim 1, characterized in that the cells (6) in the region close to the axis are smaller than the cells in the region remote from the axis. 3. A fan having an impeller and an inlet guide device on the flow path in front of the inlet area of the inlet nozzle, while the inlet guide device is made in the form of an inlet grid (1) with flat ribs (5), and these ribs (5) form a plurality of flow channels (6) in the form of grid cells, and at the same time, the inlet grid (1) has a basket contour, which has an outer region (34) in the form of a side surface of a cylinder and a flat area (33) close to the axis. 4. The fan according to one of claims 1 to 3, characterized in that in the center of the inlet grille (1) there is a region without ribs (5), i.e. without flow channels (6). 5. A fan according to one of claims 1 to 4, characterized in that the fins (6) have a fin thickness ranging from 0.25 mm to 2 mm. 6. A fan according to one of claims 1 to 5, characterized in that the contour region close to the axis extends evenly or very gently, approximately orthogonally to the central axis. 7. A fan according to one of claims 1 to 6, characterized in that the outer edge region of the inner contour runs approximately parallel to the median axis, approximately along an imaginary side surface of the cylinder. 8. Fan according to one of claims 1 to 7, characterized in that the inlet grille (1) in the outer edge region preferably has fastening means integrated with some of the ribs (5), which serve for positive and/or force-locking fastening to the inlet nozzle (2) or plate (32) of the fan nozzle. 9. The fan according to one of claims 1 to 8, characterized in that in the marginal region of the inlet grille (1) a stabilizing ring is made, which preferably includes fastening means used for positive and/or forceful fastening to the inlet nozzle (2) or fan nozzle plate (32). 10. An inlet grille for a fan according to one of claims 1 to 9.

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