Fan with optimized guard grid for reducing pressure loss

Abstract

The invention relates to a fan (1) with a rotatably mounted fan impeller (2), wherein a protective grille (3) is arranged on the fan (1) so as to cover the fan impeller (2), and the protective grille (3) has a plurality of grille elements (4) and grille openings (9) formed between the grille elements (4), whereby a grille spacing (6) is formed between the grille elements (4) transversely to a central longitudinal axis (5). Furthermore, at least in one section of the protective grille (3), at least parts of the grille elements (4) are arranged offset from one another in the direction of the central longitudinal axis (5), wherein the grille elements (4) each have a fan impeller spacing (7) from the fan impeller (2) formed in the direction of the central longitudinal axis (5). The grille spacing (6) between adjacent grille elements (4) is formed as a function of their fan impeller spacing (7).

Description

[0001] The invention relates to a fan with a rotatably mounted fan impeller, wherein a protective grille is arranged on the fan so as to cover the fan impeller, and the protective grille has a plurality of grille elements and grille openings formed between the grille elements. As a result, a grille spacing is formed between the grille elements transversely to a central longitudinal axis. Furthermore, at least in one section of the protective grille, at least parts of the grille elements are arranged offset from one another in the direction of the central longitudinal axis, wherein the grille elements each have a fan impeller spacing from the fan impeller formed in the direction of the central longitudinal axis.

[0002] In the further development of fans, the focus is particularly on increasing their efficiency. A highly efficient fan is characterized by minimizing energy consumption to optimally achieve the required air movement. The design of the fan grille, among other things, contributes to this.

[0003] In addition, the fan grille must ensure the protection of personnel from contact with the fan's moving parts. In this context, it is crucial that efforts to increase efficiency are consistent with safety aspects related to the fan grille.

[0004] There are already numerous designs in the prior art that address the safety aspects of fan grilles. EP 2 133 574 A2, for example, discloses a fan grille for axial fans, wherein the fan grille has a spatial design with a radially inner and also inwardly directed conical inner section, a radially outer end section, and a central section located between these two sections. According to EP 2 133 574 A2, only the central section is to be considered relevant in terms of flow technology. To achieve the spatial shape of the fan grille, its radial support struts are angled several times, with concentric grille struts evenly spaced from one another in the radial direction being formed on the support struts.Such a design, in which the flow-relevant section is limited to only part of the fan grille, proves to be extremely disadvantageous with regard to the efficiency of a fan with such a grille.

[0005] EP 2 410 187 A1 also shows a fan grille arrangement for a fan, wherein the fan grille arrangement has a cover part with a circular air passage opening. The cover part is generally placed in front of a rotating fan wheel, wherein the passage opening forms an air inlet for the air sucked in by the fan wheel. The fan wheel can be designed, for example, as an axial fan, radial fan, or diagonal fan. In order to close the passage opening for safety reasons to protect against accidental contact with the rotating fan wheel, a fan grille is attached to the cover part in the area of ​​the passage opening. The passage opening of the cover part also has an opening edge that tapers like a nozzle from an outer side to an inner side facing the fan wheel. This opening edge has a convex curve, particularly in longitudinal section.Alternatively, the opening edge can also have a conical slope. The fan grille is designed to match the circular opening and consists of a central, circular disk-shaped center section and several concentric protective struts. These protective struts are separated from each other by radial safety distances and are also arranged in a circular or annular manner within a grille plane. The safety distances of the two radially inner protective struts from the center section, or from each other, are smaller than the safety distances of the other, radially outer protective struts.

[0006] DE 10 2015 107 907 A1 discloses a flat flow guide grille designed as an inlet guide grille for placement in the intake area of ​​a fan. This flow guide grille has a grille web structure around an axial centerline, which includes both circumferentially spaced radial webs and coaxial circumferential webs spaced radially, as well as an outer ring. The inflow side of the flow guide grille runs flat and parallel to a radial plane of the grille.

[0007] DE 10 2017 209 291 A1 also discloses a fan with an inlet guide grille in the flow path upstream of a fan impeller. The inlet guide grille is designed in a hood-like manner with circumferentially spaced radial webs and radially spaced coaxial transverse webs. Due to the hood-like design, the grille spacing of the transverse webs varies with the distance of the transverse webs from the fan impeller.

[0008] However, the disadvantages of the above-mentioned solutions are that the effects of the design of the fan grille on the efficiency of the fan are not taken into account.

[0009] Against this background, the object of the invention is to provide a fan of the type mentioned at the outset which, while offering high safety, also has an increased efficiency.

[0010] This object is achieved according to the invention with a fan according to the features of claim 1. The further embodiment of the invention can be found in the subclaims.

[0011] According to the invention, a fan is provided with a rotatably mounted fan impeller, in particular one that can be driven by a drive, wherein a protective grille is arranged on the fan, in particular covering the fan impeller on one side. The protective grille has a plurality of grille elements, in particular arranged coaxially to one another, as well as grille openings formed accordingly between the grille elements, whereby a grille spacing, in particular a clear grille spacing, is formed between the grille elements transversely to a central longitudinal axis - of the protective grille and the fan impeller and / or the fan. Furthermore, at least in one section of the protective grille, at least parts of the grille elements are arranged offset from one another in the direction of the central longitudinal axis. Furthermore, the grille elements - and / or the grille openings - each have a fan impeller spacing from the fan impeller formed in the direction of the central longitudinal axis.According to the invention, the grid spacing between, in particular, two directly adjacent grid elements is configured depending on their fan impeller spacing. In a preferred embodiment, the grid elements are arranged offset from one another across the entire protective grid in the direction of the central longitudinal axis. The offset could be uniform or random. The grid elements primarily comprise a central element and protective struts, with the protective struts preferably being designed in the form of ring struts.

[0012] By designing the grille spacing based on the respective fan impeller spacing, effective contact protection can be provided while simultaneously improving the fan's efficiency. The grille spacing is designed to be as narrow as necessary and as wide as possible, preventing dangerous contact points with the fan impeller while ensuring the highest possible airflow through the fan. Offsetting the grille elements along the central longitudinal axis and / or adjusting the grille spacing based on the fan impeller spacing can also help reduce fan noise.

[0013] A further extremely advantageous development of the invention lies in the fact that the grille spacing of at least one pair - consequently two - of adjacent grille elements is greater than the grille spacing of at least one - further - pair of adjacent grille elements if at least one grille element of this - further - pair has a smaller fan impeller spacing. Correspondingly, a pair of adjacent grille elements would have a smaller grille spacing if their fan impeller spacing is smaller than that of another - pair of adjacent grille elements. In particular, the grille elements of a respective pair are arranged, in particular, transversely to the central longitudinal axis or radially directly adjacent to one another. This configuration of the grille spacing achieves a high degree of fan efficiency and ensures optimal airflow through the protective grille - and thus the fan - as well as effective contact protection.

[0014] A further advantageous embodiment of the invention can be seen in that the grid spacing of at least one pair of two adjacent grid elements arranged close to the central longitudinal axis is greater than the grid spacing of at least one pair of two adjacent grid elements, of which at least one grid element is arranged further away from the central longitudinal axis. Precisely because a larger grid spacing is formed between the more centrally positioned grid elements, a low-loss inflow with lower turbulence is ensured, which contributes to a further increase in the efficiency of the fan. With the preferred circular design of the protective grid and / or the grid elements, the grid spacing of radially inner grid elements would thus be greater than the grid spacing of radially outer grid elements, so that a low-loss inflow prevails, especially at throttled operating points.

[0015] A further advantageous embodiment of the invention is characterized in that each pair of adjacent grille elements has a maximum grille spacing determined by their fan impeller spacings, ensuring contact protection. The grille element with the smaller fan impeller spacing determines the maximum grille spacing of the respective pair of adjacent grille elements. This ensures, on the one hand, the contact protection required for a fan and, on the other hand, the highest possible airflow through the fan.

[0016] In a comparable embodiment of the invention, it is provided, deviating or supplementing this, that the fan impeller spacings are divided into at least two areas. Each of the fan impeller spacing areas is assigned a range of minimum and / or maximum grille spacings, which ensure contact protection. Each pair of adjacent grille elements has a grille spacing from the assigned range, depending on their fan impeller spacings. The design of the grille spacing ranges depending on the fan impeller spacing area ensures effective contact protection in various scenarios with low pressure loss. This enables safe use of the fan in a variety of environments.

[0017] Generally speaking, but particularly in connection with the above embodiment, a further development of the invention is considered advantageous in which the fan impeller spacing ranges and / or grille spacing ranges are graduated and thus delimited from one another. This clear demarcation enables precise adjustment of the grille spacing for different fan impeller spacings. The gradation facilitates the practical application of the invention, as users and developers have clear guidelines for selecting grille spacings according to the fan impeller spacing. In principle, the following relationship between fan impeller spacing ranges and grille spacing ranges can be provided: Fan wheel spacing range Grid spacing range ≥ 2 mm to 10 mm ≤ 4 mm ≥ 10 mm to 20 mm 4 mm to ≤ 6 mm ≥ 20 mm to 80 mm 6 mm to ≤ 8 mm ≥ 80 mm to 100 mm 8 mm to ≤ 10 mm ≥ 100 mm to 120 mm 10 mm to ≤ 12 mm ≥ 120 mm 12 mm to ≤ 20 mm

[0018] Furthermore, a design of the invention can be considered promising in which the fan has an inlet nozzle arranged adjacent to the protective grille in the direction of the central longitudinal axis. By combining the grille spacing design, which depends on the fan impeller spacing, and the arrangement of the inlet nozzle, a further increase in the fan's efficiency can be achieved while maintaining contact protection.

[0019] In one embodiment, the inlet nozzle surrounds the fan wheel parallel to its central longitudinal axis. This targeted surround of the fan wheel reduces turbulence in the airflow, contributing to a quieter and more efficient airflow and thus increasing efficiency. Furthermore, this minimizes fan noise.

[0020] In this practical design, the inlet nozzle tapers from the protective grille to the fan impeller, perpendicular to the central longitudinal axis. This creates a largely minimal distance between the fan impeller and the inlet nozzle, with only a small remaining annular gap, which promotes efficient airflow and minimizes airflow loss.

[0021] Furthermore, an embodiment of the invention is considered advantageous in which the grille elements are arranged evenly, in particular equidistantly, from grille element to grille element in the direction away from the central longitudinal axis of the fan wheel. This results in a conical shape for the grille elements. This embodiment advantageously minimizes turbulence during the inflow of air into the fan, as simultaneous impact on all grille elements is avoided. This consequently leads to improved airflow through the fan, which in turn increases the fan's efficiency and minimizes potential disruptive effects.

[0022] The invention permits various embodiments. To further illustrate its basic principle, one of them is illustrated in the drawing and described below.

[0023] Figure 1shows an embodiment of the fan 1 according to the invention in a simplified, schematic sectional view. The fan 1 has the rotatably mounted fan wheel 2 and the protective grille 3, wherein the protective grille 3 is arranged on the fan 1 so as to cover the fan wheel 2 on one side. The protective grille 3 also has a plurality of grille elements 4 arranged coaxially to one another transversely to the central longitudinal axis 5 of the fan 1 and corresponding grille openings 9 formed between the grille elements 4, wherein the grille elements 4 comprise the central middle element 10 and the protective struts 11 arranged coaxially thereto. The fan 1 and thus the protective grille 3 and the inlet nozzle 8 are essentially circular and / or cylindrical in design, i.e. they essentially have a circular cross-section. The protective struts 11 in this embodiment of the fan 1 are also designed in the form of annular struts.

[0024] With regard to the inlet nozzle 8, it should be explained that it is arranged adjacent to the protective grille 3 in the fan 1, wherein the inlet nozzle 8 surrounds the fan wheel 2 parallel to the central longitudinal axis 5. The inlet nozzle 8 is designed to taper transversely to the central longitudinal axis 5 from the protective grille 3 to the fan wheel 2.

[0025] Furthermore, a respective, here clear grid spacing 6 is formed transversely to the central longitudinal axis 5, i.e. correspondingly radially between the grid elements 4. In addition to this radial spacing of the grid elements 4 transversely to the central longitudinal axis 5, the grid elements 4 are also arranged offset from one another in the direction of the central longitudinal axis 5, i.e. in the axial direction, and in this case each have the fan wheel spacing 7 from the fan wheel 2, which is also formed in the direction of the central longitudinal axis 5. The grid elements 4, in this embodiment consequently the central element 10 and the protective struts 11, are arranged in particular in the direction of the central longitudinal axis 5 from grid element 4 to grid element 4 continuously and conically offset from one another, so that they each have a different fan wheel spacing 7.The respective grid spacing 6 between two coaxially adjacent grid elements 4 is designed depending on their fan wheel spacing 7.

[0026] The grid spacing 6 of at least one pair of two adjacent grid elements 4 is greater than the grid spacing 6 of at least one - further - pair of two adjacent grid elements 4, of which at least one grid element 4 or both grid elements 4 have a smaller fan impeller spacing 7. The greater the fan impeller spacing 7 of a pair of grid elements 4, the greater their grid spacing 6 is in principle. Conversely, the smaller the fan impeller spacing 7 is, the smaller the grid spacing 6 of a pair of grid elements 4. However, it should be noted that the fan impeller spacings 7 of the respective grid elements 4 are divided into at least two areas, each area of ​​fan impeller spacings 7 being assigned a range of grid spacings 6 within which the grid spacings 6 may lie.The fan impeller spacings 7 and the corresponding ranges of grid spacings 6 are graduated and thus separated from one another. Thus, as also shown in this embodiment of the fan 1, it is possible to have groups of several, for example, more than three grid elements 4, which, despite differing fan impeller spacings 7 of the grid elements 4, have the same grid spacing 6 from one another within a group.Since in this embodiment of the fan 1 the two pairs of grille elements 4 arranged close to the central longitudinal axis 5, i.e. in this embodiment radially inward, thus consisting of the central element 10 and the coaxially adjacent protective strut 11 and the protective strut 11 which in turn is coaxially adjacent to this protective strut 11, have the greatest fan wheel distance 7 to the fan wheel 2, their grille distance 6 is also larger than the grille distance 6 of the other pairs of grille elements 4, here protective struts 11, which are further spaced from the central longitudinal axis 5, i.e. are arranged radially further outwards and each have a smaller fan wheel distance 7 to the fan wheel 2. LIST OF REFERENCE SYMBOLS

[0027] 1Fan 2Fan wheel 3Protective grille 4Grille element 5Central longitudinal axis 6Grille spacing 7Fan wheel spacing 8Inlet nozzle 9Grille openings 10Central element 11Protective strut

Claims

1. Fan (1) with a rotatably mounted fan wheel (2), wherein a protective grille (3) is arranged on the fan (1) covering the fan wheel (2), and the protective grille (3) has a plurality of grille elements (4) and grille openings (9) formed between the grille elements (4), whereby a grille spacing (6) is formed between the grille elements (4) transversely to a central longitudinal axis (5), furthermore, at least in one section of the protective grille (3), at least parts of the grille elements (4) are arranged offset from one another in the direction of the central longitudinal axis (5), and the grille elements (4) each have a fan wheel spacing (7) from the fan wheel (2) formed in the direction of the central longitudinal axis (5), characterized in that the grid spacing (6) between adjacent grid elements (4) is designed depending on their fan wheel spacing (7).

2. Fan (1) according to claim 1, characterized in thatthe grid spacing (6) of at least one pair of adjacent grid elements (4) is greater than the grid spacing (6) of at least one pair of adjacent grid elements (4), of which at least one grid element (4) has a smaller fan wheel spacing (7).

3. Fan (1) according to claim 1 or 2, characterized in that the grid spacing (6) of at least one pair of adjacent grid elements (4) arranged close to the central longitudinal axis (5) is greater than the grid spacing (6) of at least one pair of adjacent grid elements (4), of which at least one grid element (4) is arranged further away from the central longitudinal axis (5).

4. Fan (1) according to at least one of the preceding claims, characterized in that a respective pair of adjacent grille elements (4) has a maximum grille spacing (6) determined by their fan wheel spacings (7) and ensuring contact protection.

5. Fan (1) according to at least one of the preceding claims, characterized in that the fan wheel spacings (7) are divided into at least two areas, each area of ​​fan wheel spacings (7) being assigned a range of grid spacings (6) ensuring contact protection, a respective pair of adjacent grid elements (4) having a grid spacing (6) from the assigned range depending on its fan wheel spacings (7).

6. Fan (1) according to at least one of the preceding claims, characterized in that the areas of fan wheel spacing (7) and / or ranges of grille spacing (6) are graduated and separated from one another.

7. Fan (1) according to at least one of the preceding claims, characterized in that the fan (1) has an inlet nozzle (8) arranged adjacent to the protective grille (3).

8. Fan (1) according to at least one of the preceding claims, characterized in thatthe inlet nozzle (8) surrounds the fan wheel (2) parallel to the central longitudinal axis (5).

9. Fan (1) according to at least one of the preceding claims, characterized in that the inlet nozzle (8) is tapered from the protective grille (3) to the fan wheel (2) transversely to the central longitudinal axis (5).

10. Fan (1) according to at least one of the preceding claims, characterized in that the grid elements (4) in the fan wheel (2) are arranged evenly offset from one another in the direction opposite to the central longitudinal axis (5).

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