EP3183459B1 - Axial fan - Google Patents

Description

The invention relates to an axial fan for use with a wall ring plate, in particular in the field of ventilation, air conditioning and refrigeration technology.

It is known from the prior art to provide fans with a wall ring plate as a structural unit, with the dimensions of the wall ring plates being standardized in order to enable the devices to be exchanged by replacing the entire structural unit. New fan solutions with wall ring plates must therefore be dimensioned (length and width of the wall ring plate) in such a way that they can replace existing systems. They are therefore subject to the space-related Length and width restrictions and must be able to use conventional EC and AC motors. Impellers with a rating based on the R20 standard series of DIN 323 or ISO 3 are used for the fans

Diameter D _standard is used, which is calculated using the following formula: $$D_{\mathit{default}}={\mathrm{i.e}}_{n-1}\times \sqrt[20]{10}$$

Standard diameters D _standard of wheels are therefore, for example, 501 mm, 562 mm, 630 mm, 707 mm, etc. A tolerance of 2% can be taken into account.

To coordinate the unit of fan and wall ring plate, the axial extension of the assembly, i.e. above all the fan, motor and possible additional components, the dimensioning and geometry of the fan space in the wall ring plate and the impeller itself can be changed.

The aim is to improve the flow mechanics of conventional axial fans in order to increase their efficiency and the air output of the motors previously used by reducing the torque requirement or to have the option of using cheaper motors with lower torque and reduced power consumption, which increase the air output in the same way delivery.

In principle, the efficiency can be increased by reducing the dynamic outlet losses (pressure recovery), as is the case, inter alia, in DE202010016820U1 is described. As design-related measures for influencing the flow with regard to swirl and outlet speed, a guide vane or a diffuser can be provided for an axial fan, for example. However, such a downstream reconversion never takes place completely and is therefore less efficient compared to measures within the axial fan that lead to a reduction in the speed in the guide the impeller.

Further printed prior art from the present technical field is in the documents WO 2008/143603 A1 , FR 2 728 028 A1 , DE 690 24 820 T2 and U.S. 7,166,940 B2 disclosed.

When using external rotor motors, the hub is larger in diameter than the motor because it sits inside the hub. With axial fans, however, a large hub increases the axial speed of the flow and thus the outlet losses for the same volume flow.

In principle, the air performance of an axial fan can be increased by enlarging the impeller. The problem here, however, is that if the installation space is retained due to the use of a wall ring plate that is based on standards in terms of its external dimensions and an increase in the wall ring diameter for the larger impeller, there is a significant deterioration in the acoustics. Therefore, in order to holistically improve the dynamic flow, measures must already be taken in the axial fan in the area of the impeller, both to reduce the dynamic outlet losses and to maintain or even improve the acoustics.

The invention is therefore based on the object of providing an axial fan with improved efficiency compared with known systems and no increased noise development, which can be used as a direct replacement for an axial fan with a wall ring plate.

This object is achieved by the combination of features according to claim 1.

The combination of an increase in the impeller diameter D _L over the standardized impeller diameter with simultaneous adjustment of the inflow geometry delivers the desired reduced torque requirement without deteriorating acoustics. Due to the increase in impeller diameter, the outlet area increases, which reduces the dynamic outlet losses and thus increases efficiency. The possibility of enlarging the impeller while maintaining the good acoustic behavior is achieved by the inflow geometry described above.

$$D_L=g\times D_{\mathit{standard}}$$

According to the invention, the impeller diameter is increased by a factor g compared to the standardized impeller diameter, while the external dimensions are retained, ie for D ₁ and D _L : $${\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">D</figure-callout>}}_1=f\times D_{\mathit{default}}$$

$$D_L=G\times D_{\mathit{default}}$$

und $${\mathrm{g}}_{\max }=-\mathrm{0,00022}\times {\mathrm{D}}_{\mathrm{standard}}+\mathrm{1,34},\mathrm{vorzugsweise}{\mathrm{g}}_{\max }=-\mathrm{0,00022}\times {\mathrm{D}}_{\mathrm{standard}}+\mathrm{1,088},$$

und $${\mathrm{f}}_{\min }=-\mathrm{0,00022}\times {\mathrm{D}}_{\mathrm{standard}}=\mathrm{1,35},\mathrm{vorzugsweise}{\mathrm{f}}_{\min }=-\mathrm{0,00028}\times {\mathrm{D}}_{\mathrm{standard}}+\mathrm{1,42}$$

und $${\mathrm{f}}_{\max }=-\mathrm{0,00028}\times {\mathrm{D}}_{\mathrm{standard}}+\mathrm{1,5},\mathrm{vorzugsweise}{\mathrm{f}}_{\max }=-\mathrm{0,00028}\times {\mathrm{D}}_{\mathrm{standard}}+\mathrm{1,46}.$$

The factors g and f are defined according to the invention in a range g _min to g _max and in a range f _min to f _max as $${\mathrm{G}}_{\mathrm{at\; least}}=-0.00008\times {\mathrm{D}}_{\mathrm{default}}+1.1$$

and $${\mathrm{G}}_{\mathrm{Max}}=-0.00022\times {\mathrm{D}}_{\mathrm{default}}+1.34,\mathrm{preferably}{\mathrm{G}}_{\mathrm{Max}}=-0.00022\times {\mathrm{D}}_{\mathrm{default}}+\mathrm{1,088},$$

and $${\mathrm{f}}_{\mathrm{at\; least}}=-0.00022\times {\mathrm{D}}_{\mathrm{default}}=1.35,\mathrm{preferably}{\mathrm{f}}_{\mathrm{at\; least}}=-0.00028\times {\mathrm{D}}_{\mathrm{default}}+1.42$$

and $${\mathrm{f}}_{\mathrm{Max}}=-0.00028\times {\mathrm{D}}_{\mathrm{default}}+1.5,\mathrm{preferably}{\mathrm{f}}_{\mathrm{Max}}=-0.00028\times {\mathrm{D}}_{\mathrm{default}}+1.46.$$

In particular, the invention is aimed at running wheels with diameters of 350 to 1300 mm, more preferably 500 to 910 mm. The impellers themselves have 3 to 13, preferably 4 to 7 blades.

und $${\mathrm{j}}_{\max }=\mathrm{0,0054}\times {\mathrm{D}}_{\mathrm{standard}}+\mathrm{8,8135},\mathrm{vorzugsweise}{\mathrm{j}}_{\max }=8.$$

In order to improve the acoustics, the housing of the axial fan is designed according to the invention in such a way that it has an inflow geometry in which a ratio j of the axial width b of the tapering section to the outer edge area extending radially perpendicularly over the length c is defined in a range j _min to j _max as $${\mathrm{j}}_{\mathrm{at\; least}}=-0.0047\times {\mathrm{D}}_{\mathrm{default}}+6.5225,$$

and $${\mathrm{j}}_{\mathrm{Max}}=0.0054\times {\mathrm{D}}_{\mathrm{default}}+8.8135,\mathrm{preferably}{\mathrm{j}}_{\mathrm{Max}}=\mathrm{8th}.$$

Due to the relationship between inflow geometry and impeller diameter in the specified range, a particularly advantageous result is achieved with regard to the efficiency of the fan wheel with a static efficiency of η>58% (according to ISO 5801) and acoustics.

In an alternative embodiment it is provided that between the outer edge area and the tapering section a stiffening web is formed which extends in the axial, radial or oblique direction, which in a favorable embodiment variant extends axially horizontally in the direction of flow or radially vertically. Such a "reinforcing bead" stiffens the housing in the inflow area and stabilizes the entire assembly of fan and wall ring plate.

vorzugsweise $$\psi <-\mathrm{0,0003}\times D_{\mathit{standard}}+\mathrm{0,425}$$

It is well known that impellers that are dimensionless and strong, in which the position of the static optimum efficiency lies at large values of the flow rate ϕ and the head coefficient ψ, which are essentially influenced by the number of blades and the angle of inclination, are acoustically better than impellers that are dimensionlessly weak. According to the invention, it is optimal for particularly positive acoustics if the position of the static efficiency optimum at a pressure coefficient value ψ (according to the ISO 5801 standard) is in a range that is defined as $$\psi \le -0.0003\times D_{\mathit{default}}+0.425,$$

preferably $$\psi <-0.0003\times D_{\mathit{default}}+0.425$$

The efficiency and acoustics of the axial fan can be further improved by the formation of winglets on each of the blades of the impeller, in particular by a one-piece formation on the radial outer areas of the blades.

In order to be able to connect different motors with different motor diameters to the impeller, it is provided according to the invention that an interchangeable motor replacement insert that matches the size of the respective motor can be arranged inside the hub of the impeller. This increases the variability of the structure and reduces the costs for different models.

The axial fan according to the invention is not limited to the adaptation of the housing in the area of the impeller. Rather, it is provided that a diffuser is arranged in one piece on the housing in the outflow area in order to ensure pressure recovery. In a preferred embodiment, the transition of the housing from the wall ring area to the diffuser is rounded.

It is also advantageous if, for comparatively high back pressures in the axial fan according to the invention, a guide vane is used in the outflow area on the housing, which vane can advantageously be retrofitted as an option.

In one embodiment of the invention, as protection against accidental contact, it is also provided to use a protective grid on the housing in the outflow area. The protective grid can be designed as an insert in the diffuser and have meshes or rings that match in shape and size.

Furthermore, an embodiment with a one-piece impeller is favorable. According to the invention, in an advantageous embodiment, it is provided that the blades are profiled or sickled. According to the invention, an impeller made of plastic injection molding or die-cast aluminum is proposed as a favorable manufacturing method.

Fig. 1

eine Vorderansicht auf einen Axialventilator mit Wandringplatte;

Fig. 2

eine dreidimensionale, teilweise geschnittene Ansicht einer Hälfte des Axialventilators aus Fig. 1;

Fig. 3

eine alternative Ausführung des Axialventilators aus Fig. 2; und

Fig. 4

ein Diagramm zur erfindungsgemäß erreichten Druckzahl.

Other advantageous developments of the invention are characterized in the dependent claims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. Show it:

1

a front view of an axial fan with wall ring plate;

2

Figure 12 shows a three-dimensional, partially sectioned view of one half of the axial flow fan 1 ;

3

an alternative design of the axial fan 2 ; and

4

a diagram of the pressure number achieved according to the invention.

The figures are schematic by way of example. Name the same reference numbers equal parts in all views. The outer dimensions or diameters referred to above and in the claims as D ₁ , D _A , D _L , D _WR , D _standard are each underlined in the figures and below, ie as D_1, D_A, D_L; D_WR, D_standard marked.

In figure 1 a low-pressure axial fan 1 with a rectangular wall ring plate 9 formed in one piece with the side edge lengths D_2 and D_1 (D1<D2) is shown in a front view, the plan view offering a view in the direction of flow and with five impeller blades extending radially outwards from the hub 6 2 trained impeller 20 in the center of the axial fan 1 can be seen. The annular wall plate 9 has standard dimensions and, together with the axial fan 1, forms a structural unit that enables direct exchange with existing systems, for example in condensers, heat exchangers, refrigeration systems and the like.

figure 2 shows one half of the axial fan 1 in a three-dimensional, partially sectioned view. It goes without saying that the half opposite the axial center line is mirrored and identical in design. The axial fan 1 comprises a motor 8 designed as an external rotor, which is arranged inside the hub 6 and is connected to the impeller 20 via a motor replacement insert 7 that matches the dimensions of the motor 8 . The motor replacement insert 7 can be detachably attached to the hub 6 . The motor 8 drives the hub 6 and thus the impeller 20 via the motor interchangeable insert 7 .

The housing 10 of the axial fan 1 has, seen in the direction of flow from left to right, an inflow area 11 with the maximum external housing dimension D_1, a tapered section 4 with a partially elliptically curved cross section, a central section 14 that extends axially horizontally, and a central section 14 that is designed with a diffuser 3 Outflow area 12 on. The opening angle "alpha" of the diffuser 3 is about 12 degrees. The overall axial length of the axial fan 1 is marked with h. The impeller 20 is arranged in the axial fan 1 essentially at the level of the middle section 14, with a vertical plane at the boundary between the middle section 14 and the diffuser 3 intersecting the impeller 20 in the radial direction. At its radial end section, each blade 2 of the impeller 20 has a winglet 21 which extends along the axial outer edge.

The impeller 20 also has an enlarged impeller diameter D_L compared to an impeller diameter D_standard based on DIN 323 or ISO 3, so that the ratio of D_1/D_L is smaller than the ratio of D_1/D_standard. Due to the increase in diameter of the impeller 20 compared to the standardized impeller diameter D_standard, the exit surface of the axial fan 1 increases, which reduces its dynamic exit losses and increases efficiency. In the embodiment shown, the impeller diameter D_L is approx. 10% larger than the standardized impeller diameter D_standard.

In the inflow area 11 , an outer edge area 5 is formed on the inflow side, which extends from the housing outer diameter D_1 to the inflow diameter D_A radially perpendicularly over a length c/2 and is adjoined by the narrowing section 4 viewed in the axial flow direction. The radial length c of the outer edge area 5 results from the difference between the outer housing dimension D_1 and the definable inflow diameter D_A. The axial width b and radial length a of the tapering section 4 form a ratio of a/b which, in the embodiment shown, corresponds approximately to the value 0.5. The lengths a and b are measured, taking into account the wall thickness of the housing 10. The length b ends at the point at which the housing 10 is completely in the horizontal middle section 14 merges, ie no arc shape of the tapering section 4 can be detected. The length a ends at the point at which the housing 10 merges into the completely vertical outer edge region 5, ie the tapered section 4 is no longer in an arc shape. The axial end of the tapered section 4 in the direction of flow forms a vertical plane which in the embodiment shown essentially coincides with the front edge of the hub 6 .

figure 3 shows an execution according to figure 2 alternative embodiment in which all the features are identical, but on the housing 10 of the axial fan 1 in the inflow area 11 between, i.e. in the transition from the outer edge area 5 to the tapering section 4, a stiffening web 13 extending horizontally in the axial direction is additionally formed to stiffen the inflow area 11 is. In this embodiment, the dimension a of the tapered section 4 can be determined even more easily, since it extends to the axial inside of the axially horizontal stiffening web 13 .

figure 4 shows the reduction in the pressure coefficient ψ of the axial fan 1 according to the invention compared to those of the prior art based on the standardized impeller diameter D_standard. The static optimum efficiency of the axial fan 1 according to the invention is surprisingly at a pressure coefficient value ψ≦−0.0003×D_standard+0.425, ie at or below the limit curve drawn in the diagram, whereas the impellers according to the prior art with and without guide vane are always above the limit curve .

The implementation of the invention is not limited to the preferred exemplary embodiments specified above. Rather, a number of variants are conceivable which make use of the solution shown even in the case of fundamentally different designs. For example the number of blades of the impeller is not limited to five, but can be in the range of 3 to 13, in particular 4 to 7. Furthermore, a guide vane (not shown in the figures) can be used to optimize the flow, and a protective grid can be used to protect against accidental contact.

Claims (8)

1. An axial fan for use with a wall ring plate (9), comprising a motor (8), a housing (10) with an inlet region (11) and an outlet region (12), and a rotor (20) which can be driven by the motor (8), wherein the housing (10), on the inlet side, has an outer housing dimension (D₁) and the rotor (20) has an increased rotor diameter (D_L) as compared with a rotor diameter (D_standard) which is standardized based on the standard series R20 of DIN 323 or ISO 3, so that a ratio of D₁/D_L is less than a ratio of D₁/D_standard, wherein, on the inlet side, the inlet region (11) has a tapered section (4) that narrows in an arched manner in a cross-sectional view from an inlet diameter (D_A) to a wall ring diameter (D_WR), the axial width (b) and radial length (a) of which tapered section form a ratio of (a)/(b) in a range from 0.3 to 0.7, in particular 0.4 to 0.6, wherein the motor (8) is configured as an external rotor motor, and the rotor (20) has a hub (6) in which the motor (7) is received, wherein a motor replacement insert is arranged inside the hub (6), wherein different motors with different motor diameters can be connected to this insert, and wherein in the outlet region (12), a diffusor (3) is arranged integrally on the housing (10), and in that a transition of the housing (10) from the wall ring region (1) to the diffusor (3) is rounded off, wherein

   the rotor diameter (D_L) is increased by the factor g with a constant outer housing diameter (D₁) as compared with the standardized rotor diameter (D_standard), wherein the factor g is defined in a range of g_min to g_max, wherein $${\mathrm{g}}_{\min }=-0.00008\times {\mathrm{D}}_{\mathrm{standard}}+1.1$$

   

   and $${\mathrm{g}}_{\max }=-0.00022\times {\mathrm{D}}_{\mathrm{standard}}+1.34,$$

   

   and wherein

   the housing (10) has an inlet geometry in which a ratio j of the axial width (b) to the outer edge region (5) extending radially vertically over the length (c) is defined in a range of jmin to jmax, wherein $${\mathrm{j}}_{\min }=-0.0047\times {\mathrm{D}}_{\mathrm{standard}}+6.5225,$$

   

   and $${\mathrm{j}}_{\max }=0.0054\times {\mathrm{D}}_{\mathrm{standard}}+8.8135.$$

   
2. The axial fan according to claim 1, characterized in that the wall ring plate (9) has standardized outer dimensions and is round or rectangular, wherein in the case of a rectangular configuration, its shorter side edge and in the case of a round configuration its total diameter corresponds to the outer housing dimension (D₁).
3. The axial fan according to at least one of the preceding claims, characterized in that the wall ring plate (9) is integrally formed on the housing (10).
4. The axial fan according to at least one of the preceding claims, characterized in that, on the inlet side, the inlet region (11) of the housing (10) has an outer edge region (5) extending from the outer housing dimension (D₁) to an inlet diameter (D_A) in a radially vertical manner over the length (c), which outer edge area is followed by the tapered section (4), as viewed in the direction of axial flow.
5. The axial fan according to at least one of the preceding claims 1 to 4, characterized in that the outer edge area (5) extending radially vertically over the length (c) is determined from the difference of the outer housing dimension (D₁) and the inlet diameter (D_A).
6. The axial fan according to any of the preceding claims 4 to 5, characterized in that a reinforcement web (13) is formed between the outer edge region (5) and the tapered section (4).
7. The axial fan according to one of the preceding claims, characterized in that the ratio j is defined in the range j_min to j_max, wherein $${\mathrm{j}}_{\min }=-0.0047\times {\mathrm{D}}_{\mathrm{standard}}+6.5225,$$

   

   and $$\mathrm{jmax}=8.$$

   
8. The axial fan according to at least one of the preceding claims, characterized in that the rotor (20) comprises a plurality of blades (2), with a winglet (21) being integrally formed on the radial outer region of each blade.

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