Vanes for the impeller of a ventilator, impeller, and axial ventilator, diagonal ventilator, or radial ventilator

Abstract

The invention relates to vanes for the impeller of a ventilator, in particular an axial ventilator, diagonal ventilator, or radial ventilator, comprising a waved leading edge and a waved trailing edge, wherein the waves on the leading edge have a larger wavelength than the waves on the trailing edge. The invention also relates to an impeller with corresponding vanes and to axial ventilators / diagonal ventilators and radial ventilators comprising an impeller with corresponding vanes.

Description

[0001] The invention relates to a blade for the impeller of a fan, in particular an axial fan, diagonal fan or radial fan.

[0002] Furthermore, the invention relates to an impeller equipped with corresponding blades as well as an axial fan or diagonal fan or radial fan, each with an impeller equipped with corresponding blades.

[0003] Providing fans with low noise emissions while achieving specific required air performance (volume flow and pressure increase) and efficiency levels is of fundamental interest to fan manufacturers. In particular, noise emissions should also be low for fans integrated into a system.

[0004] From EP 2 418 389 A2, an axial fan is known which, due to a special design of the impeller in the radially outer area of ​​the fan blades, exhibits particularly low noise emissions in the broadband frequency range, which are caused by leakage flow at the head gap. This special design is achieved in particular by the fact that, locally in the radially outer area, the path of the fan blades, viewed in the span direction, is characterized by a significant deviation from the path in the span direction found in the rest of the fan blades. However, such a design of the impeller cannot reduce, or can only reduce insufficiently, the tonal noise caused by inflow disturbances. Likewise, such a design cannot reduce, or can only reduce insufficiently, the trailing edge noise.

[0005] From US 2013 / 0164488 A1, a profiled fan blade is known which, by means of a special wavy design of its leading edge in a fan, can reduce the tonal noise caused by inflow disturbances.

[0006] WO 17036470 A1 discloses an impeller or vane for an axial or diagonal fan in which both the leading and trailing edges are corrugated. The leading and trailing edges feature corrugations with substantially identical wavelengths and amplitudes. Practical experience shows that the tonal noise generated by inflow is considerable, especially at high speeds.

[0007] Documents EP 1 801 422 A2 and JP 2017 070337 A each show blades for fans according to the preamble of claim 1.

[0008] The present invention is based on the objective of designing and further developing blades for the impeller of a fan, in particular an axial fan, diagonal fan or radial fan, in such a way that the acoustics are improved during the operation of such a fan, in particular the noise emissions are reduced.

[0009] The foregoing problem is solved with respect to the wing according to the invention by the features of claim 1. According to this claim, the wing has, among other things, a wavy leading edge and a wavy trailing edge, wherein the waves at the leading edge have a longer wavelength than the waves at the trailing edge.

[0010] It has been recognized that the features of claim 1 achieve an improvement in acoustics by reducing leading-edge noise, specifically through leading-edge optimization. The measures taken at both the leading and trailing edges produce a synergistic effect, at least when the waves at the leading edge have a longer wavelength than the waves at the trailing edge. Ultimately, this represents leading-edge optimization by influencing the leading-edge geometry in combination with optimization in the area of ​​the trailing edge.

[0011] Specifically, it is advantageous if the wavelength of the waves at the leading edge is at least 1.5 times greater than the wavelength of the waves at the trailing edge. Preferably, the wavelength of the waves at the leading edge is 2 to 10 times greater than the wavelength of the waves at the trailing edge.

[0012] In the embodiments discussed here, preferably 5 to 10 wave crests are evenly or unevenly distributed across the span at the leading edge. Preferably, 5 to 50 waves are evenly or unevenly distributed across the span at the trailing edge, whereby it is not necessary for the waves to extend over the entire leading edge and / or the entire trailing edge. It is sufficient if the waves are preferably formed in an area facing away from the hub or hub ring.

[0013] According to the invention, the wavelength of the waves at the leading edge increases from the wingtip or cover ring towards the hub or hub ring. Additionally, the amplitude of the waves can also increase in the same way. The wavelength and / or amplitude of the waves increase at the trailing edge from the hub or hub ring towards the wingtip or cover ring.

[0014] Due to the unique geometry of the waves at the trailing edge, they can be described as "jagged." Thus, the features at the trailing edge can be called spikes, a term used in the broadest sense. The spikes at the trailing edge differ from the waves at the leading edge in their shorter wavelength relative to the amplitude or wave / spike height, and possibly also in their steeper flanks and more pointed wave crests.

[0015] The free ends of the waves or teeth can be more or less sharp-edged. For safe handling during installation, it is advantageous if their free ends are rounded or flattened. It is also conceivable that the teeth are coated with a protective film, varnish, etc.

[0016] The invention relates primarily to the design of the leading and trailing edges of the wing. Furthermore, the wing has a three-dimensionally twisted shape. It is a further advantage if the wing, while three-dimensionally twisted, is not corrugated within itself. This measure also reduces noise emissions.

[0017] If the blade is intended for an axial or diagonal fan, it is further advantageous if the blade tips are equipped with so-called winglets, namely end-facing bends or rounded edges that curve from the pressure side towards the suction side. Such winglets are well known from aviation. This measure also reduces noise emissions and may increase performance.

[0018] As mentioned previously, the waves extend – both along the leading and trailing edges – at least across part of the wingspan. It is also conceivable that the waves are zonal or formed in groups with different wavelengths and / or amplitudes.

[0019] The wing can be made of different materials, for example sheet metal. In such a design, it is advantageous if at least the trailing edge area is painted or powder-coated, specifically in the area of ​​the serrations.

[0020] The blades can be manufactured from plastic using injection molding or from aluminum using die casting, resulting in a particularly simple design. If the blade is made of sheet metal, it is preferably assembled into an impeller by stamping or laser cutting, followed by embossing, joining / welding, interlocking, etc., which is then used in an axial fan, diagonal fan, or centrifugal fan. The impellers are designed and manufactured according to requirements, with the blades of an axial fan extending outwards from a hub to a free end.

[0021] When used in a radial fan, the blades extend between a hub ring and a cover ring and are rigidly connected to both. Regarding the design of the leading and trailing edges, the same principles apply as with previously described fan types, since the fundamental aim is to reduce noise emissions, particularly leading and trailing edge noise, through measures applied to both the leading and trailing edges.

[0022] There are now various ways to advantageously develop and further refine the teaching of the present invention. 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 the inventive wings or impeller with reference to the drawing. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and further developments of the teaching are also explained. The drawing shows Fig. 1 in perspective view an embodiment of an impeller of axial design according to the invention, Fig. 2 in axial top view, seen from the downstream side, the impeller made of Fig. 1 , Fig. 3 in axial top view, seen from the inflow side, the impeller from Fig. 1 und 2 , Fig. 4 in axial top view, seen from the downstream side, a wing of the embodiment according to Fig. 1 bis 3 with schematic representations, Fig. 4a a detailed view of the Fig. 4 Regarding the wing trailing edge area, Fig. 4 leg detail view of the Fig. 4 Regarding the leading edge area of ​​the blade, Fig. 5 shows a graphical representation of the sound power level of a fan with an impeller according to the invention in comparison to the prior art, Fig. 6 shows a perspective view of an embodiment of an impeller of radial design according to the invention, and Fig. 7 shows a side view of the embodiment. Fig. 6 , Fig. 8 a single wing of the exemplary embodiment made of Fig. 6 and 7 , viewed from the suction side, Fig. 9 the wing according to Fig. 8 , in a perspective view, Fig. 10 a detailed view of the wheel according to Fig. 6 and 7, seen from the side, Fig. 11 a wing of a further embodiment, seen from the suction side, with centering devices, wherein the wing is shown in its development, Fig. 12 the wing according to Fig. 11 with representations of the wavelengths, where the wing is shown in its unfolded state, Fig. 13 a detailed view of the Fig. 12 Regarding the wing trailing edge area, Fig. 14 shows a detail view similar to the Fig. 13 , concerning the wing trailing edge area, wherein a three-dimensionally embossed wing is shown, Fig. 15 a detailed view, in section and from the side, of the impeller Fig. 6 and 7 .

[0023] Fig. 1 Figure 1 shows a perspective view of an impeller 1 of an axial fan according to the invention. Five blades 2 are attached to a hub 3. Other numbers of blades are also conceivable for such an impeller, advantageously three to nine blades. The impeller 1 is manufactured from fiber-reinforced plastic by injection molding. Other manufacturing methods are also conceivable, for example, aluminum die casting or a welded sheet metal construction. In the exemplary embodiment, the impeller 1 is shown as a one-piece impeller; however, it can also be assembled from individual blades with a hub to form an impeller or be a complete die-cast rotor, wherein parts of the motor rotor are integrally connected to the impeller.

[0024] The wings 2 have a leading edge region 6 and a trailing edge region 7. The leading edge regions 6 and the trailing edge regions 7 of the wings each connect the printed sides 28 of the wings 2 and the in Fig. 3 The suction surfaces 29 of the wings 2 are recognizable. A wingtip 5 is formed at the radially outer end. A waviness is visible on the leading edge region 6 of the wings 2, with approximately seven wave crests unevenly distributed over the wingspan. A waviness is also formed on the trailing edge region 7, with the waviness being jagged at the trailing edge. The wavelength of the waviness on the trailing edge region 7 is significantly shorter than that of the waviness on the leading edge, at least by a factor of 1.5. In the exemplary embodiment, thirteen wave crests or jagged edges are distributed over the wingspan on the trailing edge region 7.

[0025] In Fig. 2 is the embodiment according to Fig. 1 The axial plan view from the downstream side is shown. The wings 2 have a three-dimensional, twisted shape but are not corrugated; that is, a planar section through such a wing 2 would show no corrugation. The corrugation is visible at the leading edge region 6 and, in a jagged pattern, at the trailing edge region 7. The wingtips 5 have winglets that are curved from the pressure side to the suction side to further improve acoustics. This illustration also clearly shows that the wavelength of the corrugation at the leading edge region 6 is significantly larger than that at the trailing edge region 7, advantageously by a factor of approximately two to ten. This ratio has proven particularly beneficial for achieving low noise levels. Both low tonal noise levels due to inflow disturbances and low trailing edge noise are achieved.The interplay of the waviness at the leading edge area 6 with the large wavelengths and rather small amplitudes with the waviness at the trailing edge area 7 with the small wavelengths and rather large amplitudes, which therefore appear rather jagged, leads to a particularly low overall noise level of a fan with a corresponding impeller 1.

[0026] In Fig. 3 is the embodiment according to Fig. 1 und Fig. 2 The axial plan view from the inflow side shows the suction sides 29 of the blades 2. The impeller 1 rotates clockwise in this view. The blade tips 5 at the leading edge regions 6 lead the blades 2 in the direction of rotation, and the blades 2 are forward-curved. This is advantageous, especially in a radially outer area, for low noise levels and pressure stability. The wavy, serrated trailing edge region 7 has a sharp separation edge at the transition to the blade suction side 29, which is particularly advantageous for low trailing edge noise.

[0027] Fig. 4 The figure shows, in axial plan view, seen from the downstream side, a blade 2 of the impeller according to the Fig. 1 bis 3 with additional schematically represented details. The partial diameter 10 is shown for each wave crest and trough of the waves on the leading edge region 6 of the wing 2. The wavelength 11 (λw) of the corrugated leading edge region 6 increases from the wingtip 5 (at the outer diameter RA) to the hub 2 (at the hub diameter RN). The wavelength 12 (λz) of the corrugated or serrated trailing edge region 7 is smaller by a factor of 1.5 - 3 than the wavelength 11 (λw) of the corrugated leading edge region 6 and decreases from the wingtip 5 to the hub 2. It can also be seen that the trailing edge region 7 is not corrugated or serrated in a region near the hub 3.

[0028] Fig. 4a shows a detail from Fig. 4 On the wing trailing edge region 7, a wavelength 12 (λz) of the waviness of the wing trailing edge region 7 is shown, which can be measured from crest to crest or from trough to trough. The wavelength 12 (λz) can, as in the example shown, vary over the span of the wing trailing edge region 7. The height 21 (Hz) of the waves or spikes on the wing trailing edge region 7 is also shown. It corresponds approximately to twice the amplitude of a waviness. Hz can also vary over the span of the wing trailing edge region 7, but in the exemplary embodiment, it is advantageously approximately constant over a wide range. At the wave crests on the wing trailing edge region 7, a relatively small radius of curvature < 0.3*Hz is formed, which makes this waviness appear more jagged.

[0029] Fig. 4b shows a detail of the Fig. 4 at the wing leading edge region 6. A wavelength 11 (λw) of the waviness of the wing leading edge region 6 is shown, which can be measured from crest to crest or from trough to trough. In the exemplary embodiment, the wavelength 11 (λw) is variable over the span of the wing leading edge region 6. The height or twice the amplitude 22 (Hw) of the waves at the wing leading edge region 6 is also shown. It corresponds approximately to twice the amplitude of a waviness. The wave crests can be, for example, in an axial view as Fig. 4b The wave troughs are connected by a line 24 and by a line 23. The distance between these two lines corresponds approximately to Hw, which in the exemplary embodiment is approximately constant over the span of the wing leading edge region 6.

[0030] Fig. 5 Figure 1 shows the sound power level of a fan with an impeller according to the invention compared to an impeller with only a serrated trailing edge according to the prior art, at constant speed and variable volume flow. The sound power level is significantly reduced by the design according to the invention over a wide range of volume flow rates.

[0031] Fig. 6 Figure 1 shows a perspective view of an embodiment of an impeller 1 of a radial fan according to the invention. This embodiment is made of sheet metal. The five blades 2 are manufactured from sheet metal by laser cutting and embossing. They are welded to the hub 3 and the cover ring 4. A waviness is visible on the leading edge region 6 of the blades 2 along the silhouette line, with approximately eight wave crests distributed approximately evenly over the span. A clearly visible wavy, rather jagged, feature is visible on the trailing edge region 7 of the blades, which is superimposed on a second waviness, comparable in wavelength and wave amplitude to the waviness of the leading edge region 6. Approximately 48 waves or jagged edges are distributed over the span along the trailing edge region 7. It is particularly advantageous that significantly more waves or jagged edges are present.The serrations on the trailing edge area 7 of the wing are formed as waves on the leading edge area 6 of the wing, in the exemplary embodiment six times as many, advantageously two to ten times as many.

[0032] Fig. 7 shows in a side view the embodiment according to Fig. 6 It consists of a hub 3, 5 blades 2, and a cover ring 4. The cover ring 4 has an air inlet opening (right) through which air is drawn in during operation of the fan. The blades 2 have a three-dimensional, twisted shape. In particular, the blade pressure sides 28 and the blade suction sides 29 do not run parallel to the axis of rotation of the impeller 1 over a considerable area. Such a three-dimensional design is advantageous for the airflow, efficiency, and acoustics of a fan with the impeller 1. The delicate serrations or waves on the trailing edge regions 7 are clearly visible. The waviness on the leading edge regions 6 is also visible. This has a significantly longer wavelength than the serrated waviness on the blade trailing edge region 7.

[0033] Fig. 8 shows a single wing 2 of the embodiment from the Fig. 6 and 7Viewed from the printed side 28. In this embodiment, the blade 2 is made of sheet metal in two steps: laser cutting and embossing. It has a corrugated leading edge area 6 and a corrugated or serrated trailing edge area 7. The corrugation at the leading edge area 6 reduces the rotational noise caused by inflow disturbances. The serration at the trailing edge area 7 reduces or eliminates trailing edge noise. Achieving a thin trailing edge on such sheet metal blades is often complex, which is why the technology of reducing trailing edge noise through a corrugated or serrated design is particularly suitable here. The combination with the corrugated leading edge area 6 results in a particularly quiet fan. In this embodiment, the blades 2 are welded to the hub 3 and the cover ring 4. Other connections are also conceivable (e.g., tabs).In general, it is also conceivable to manufacture one- or multi-part impellers according to the invention, for example from plastic by injection molding.

[0034] Fig. 9 shows wing 2 according to Fig. 8 In a perspective view, the entire surfaces of the pressure sides 28 and suction sides 29 of the vanes 3 exhibit a corrugation embossed into the sheet metal vane in this embodiment. The three-dimensional, twisted shape is clearly visible. Furthermore, the three-dimensional, twisted shape and the embossed corrugation stiffen the vane 2; that is, the embossed corrugation has a beneficial effect on the strength and dimensional stability of the vane 2.

[0035] Fig. 10 shows a detailed view of wheel 1 according to the Fig. 6 and 7Viewed from the side. It is clearly visible that the wavelengths of the waves or spikes at the trailing edge region 7 are considerably smaller than the wavelengths of the waviness at the leading edge region 6, specifically by a factor of approximately 6 in the exemplary embodiment.

[0036] Fig. 11 Figure 28, viewed from the printed side, shows the wing 2 of a further embodiment with centering devices, where the wing 2 is shown in its developed state, i.e., in its sheet metal blank before embossing. The finished wing 2 is produced from this blank by embossing. The corrugated / jagged shape of the trailing edge area 7 is already clearly visible during the blanking process. The embossing die does not have the jagged edges of the trailing edge area 7, as they are already present during blanking. This is an advantage, as these delicate structures do not need to be formed in the embossing tool. The corrugation of the leading edge area 6 is also already visible on the flat blank. Various centering devices 18, 19 are provided at the hub-side end 9 of the wing 2 and at the cover ring-side end 13 of the wing 2.The semicircular centering devices 19, located approximately in the middle, serve to position the wing 2 in the embossing tool, while the angular centering devices 18 serve to position the wing 2 relative to the hub and cover ring during the welding process.

[0037] Fig. 12 shows wing 2 according to Fig. 11 with representations of the wavelengths, where the wing, as in Fig. 11 , shown before embossing as a sheet metal blank. A wavelength 11 (λw) at the leading edge region 6 of the wing and a wavelength 12 (λz) at the trailing edge region 7 are indicated. In this embodiment, the wavelength 11 (λw) is also superimposed on the wavelength 12 (λz) at the trailing edge region 7, since the wavelength 11 (λw) is pronounced over the entire wing 2 and its pressure side 28 and its suction side 29 (cf. Fig. 15 The smaller wavelength of the serrations at the trailing edge region 7 is denoted by λz. In the exemplary embodiment, λw is approximately 6 times λz; a factor of 2-10 is advantageous.

[0038] Fig. 13 shows a detailed view of the Fig. 12 Regarding the trailing edge region 7 of the blade. The height 21 (Hz) of the waves or serrations on the trailing edge region 7 of the blade is advantageously at least as large as the wavelength 12 (λz) of the waves or serrations on the trailing edge region 7 of the blade, preferably at least 1.4* λz. The serrations or waves on the trailing edge region 7 of the blade thus have a relatively large height compared to their wavelength. λz, in turn, is advantageously not greater than twice the thickness of the sheet metal or the thickness of the blade 2 at its trailing edge region 7, particularly in the case of sheet metal blades, preferably not greater than 1.5 times this thickness, in order to minimize the sound level of a fan with an impeller with blades 2 in conjunction with the corrugated leading edge region 6 of the blade.

[0039] Fig. 14 shows a detailed view similar to Fig. 13 , concerning the trailing edge area 7 of the wing, where part of a three-dimensionally embossed wing 2 is shown. The waves or serrations are not pointed at their outer end (wave crest) but flattened. This reduces the risk of damage to the serrations and the risk of injury when handling the impeller 1. Sheet metal wings with wave-shaped / serrated trailing edge areas 7 are advantageously powder-coated or painted. This softens sharp edges and further reduces the risk of injury.

[0040] Fig. 15 shows a detailed cross-sectional and side view of wheel 1 according to Fig. 6 and 7The wing 2 extends between the hub 3 and the cover ring 4. The outflow end 16 of the cover plate and the outflow end 15 of the base plate are curved in such a way that the outlet area of ​​the impeller 1 is increased, thereby improving the static efficiency. The section 20 through the wing 2, which exhibits waviness, clearly shows that the wing 2 has waviness over at least a large portion of its length. The wing pressure side 28 and the unseen wing suction side 29 exhibit this waviness. The wavelength of this waviness on the wing pressure sides 28 and the wing suction sides 29 is equal to or similar to the wavelengths of the wing leading edge regions 6. The waviness can extend to the wing trailing edge regions 7, where it then appears superimposed on the waves / sharps of the wing trailing edge regions 7, which have a significantly shorter wavelength. Bezugszeichenliste

[0041] 1 Impeller 2 Blade 3 Hub / Hub Ring 4 Cover Ring 5 Blade Tip, Winglets 6 Blade Leading Edge Area 7 Blade Trailing Edge Area 8 Blade Span 9 Hub-Side Blade End 10 Part Diameter, Span Position 11 Shaft Length Leading Edge λw 12 Shaft Length Trailing Edge λz 13 Cover Ring-Side Blade End 14 Inlet Opening 15 Outflow End of Hub / Hub Ring 16 Outflow End of Cover Ring 17 Centering Device Blade - Hub 18 Centering Device Blade - Cover Ring 19 Centering Device Blade for Embossing Tool 20 Section Through the Blade 21 Height Hz of the serrations / shafts at the trailing edge area, twice the amplitude 22 Height Hw of the serrations / shafts at the leading edge area, twice the amplitude 23 Line of the Wave troughs at the leading edge area 24 Line of wave crests at the leading edge area 25 Center line of waves at the leading edge area 26 Line of wave troughs at the trailing edge area 27 Line of wave crests at the trailing edge area 28 Wing pressure side 29 Wing suction side

Claims

1. Vane (2) for the impeller of a fan, in particular an axial fan, diagonal fan or radial fan, with an undulating front edge and undulating rear edge, wherein the undulations at the front edge have a larger wavelength than the undulations at the rear edge, wherein the vane has a three-dimensional twisted form, wherein the undulation at the front edge region (6) has large wavelengths and rather small amplitudes and at the rear edge region (2) small wavelengths and rather large amplitudes, characterised in that the wavelength of the undulating front edge region increases from a vane tip or from a covering ring towards a hub or to a hub ring.

2. Vane according to claim 1, characterised in that the wavelength of the undulations at the front edge is at least 1.5 times as great as the wavelength of the undulations at the rear edge (7), preferably greater by a factor of from 2 to 10.

3. Vane (2) according to claim 1 or 2, characterised in that at the front edge (6) over the span from 5 to 10 wave peaks are preferably distributed in a uniform or non-uniform manner.

4. Vane (2) according to any one of claims 1 to 3, characterised in that at the rear edge (7) over the span from 10 to 50 waves are preferably distributed in a uniform or non-uniform manner.

5. Vane (2) according to any one of claims 1 to 4, characterised in that the wavelength of the undulations and / or the amplitude of the undulations at the rear edge (7) increases from the hub or the hub ring (3) towards the vane tip (5) or the covering ring (4).

6. Vane (2) according to any one of claims 1 to 5, characterised in that the undulations at the rear edge are in the form of prongs, wherein the prongs may be rounded or flattened at the free end thereof.

7. Vane (2) according to any one of claims 1 to 6, characterised in that it is twisted in a three-dimensional manner, but is not undulated per se.

8. Vane (2) according to any one of claims 1 to 7, wherein the vane is intended for an axial fan or a diagonal fan, characterised in that the vane tip (5) is provided with a winglet which is curved from the pressure side (28) towards the intake side (29).

9. Vane (2) according to any one of claims 1 to 8, characterised in that the undulations extend at least over a portion of the front edge (6) and the rear edge (7).

10. Vane (2) according to any one of claims 1 to 9, characterised in that it is produced from sheet metal and is preferably painted or powder-coated at least in the rear edge region (7).

11. Vane (2) according to any one of claims 1 to 9, characterised in that it is produced from plastics material, preferably using injection-moulding technology, or from aluminium, preferably using die-casting technology, or from sheet metal, preferably using punching technology.

12. Impeller (1) having at least two, preferably from three to nine vanes (2) according to any one of claims 1 to 11, characterised in that the vanes (2) individually or the entire impeller (1) is / are produced in one piece from plastics material using injection-moulding technology or from aluminium using die-casting technology or from sheet metal using punching technology or by means of laser cutting and stamping and joining / welding, inserting flaps one inside the other, etcetera.

13. Axial fan or diagonal fan having a hub and vanes which extend outwards from the hub according to any one of claims 1 to 11.

14. Radial fan having a hub ring (3), a covering ring (4) and an impeller (1) which extends between the hub ring (3) and the covering ring (4), having vanes (2) according to any one of claims 1 to 7 or 9 to 11.

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