EP3289224A1

EP3289224A1 - Fan wheel, fan, and system having at least one fan

Info

Publication number: EP3289224A1
Application number: EP16763436.9A
Authority: EP
Inventors: Frieder Loercher; Georg Hofmann; Sandra Hub
Original assignee: Ziehl Abegg SE
Current assignee: Ziehl Abegg SE
Priority date: 2015-08-31
Filing date: 2016-08-04
Publication date: 2018-03-07
Also published as: JP2018526569A; RU2018111402A3; RU2018111402A; CN108350904A; JP2022033974A; DE102015216579A1; BR112018003066A2; RU2740612C2; US20190024674A1; US11371529B2; BR112018003066B1; WO2017036470A1; CN108350904B

Abstract

The invention relates to a fan wheel for a fan comprising at least two undulate fan blades. A fan has at least one such fan wheel. A system has at least one fan having such a fan wheel.

Description

FAN WHEEL, FAN AND SYSTEM WITH AT LEAST ONE

FAN

The invention relates to a fan, a fan and a system with at least one fan.

Fan wheels are generally understood to mean radial fan wheels, diagonal fan wheels, axial fan wheels, but also leading or following wheels (stators) of fans.

The provision of fans with low noise emissions while achieving certain required airflow rates (flow rate and pressure increase) is of fundamental interest to manufacturers of fans. In particular, even with fans, which are installed in a system, the noise emissions should be low. Frequently, in such systems inflow disturbances are present at the entrance to the fan. Such inflow disturbances cause high levels of noise (tonal noise) in ordinary fans, especially at discrete frequencies which are integer multiples of the blade repetition frequency. If a fan consists of several fan wheels, for example a stator and a rotor, the downstream fan wheel experiences inflow disturbances, which are caused by the upstream fan wheel. This leads to strong, especially tonal noise. Furthermore, it is advantageous for manufacturing and / or economic reasons to have fan blades made of sheet metal (un profiled fan blades). However, fans with such wings tend to have broadband noise emissions (broadband noise). Furthermore, the blunt trailing edge of fan blades, which may be present in unprofiled and profiled fan blades, a noise source (trailing edge noise). From EP 2 418 389 A2 an axial fan is known per se, which has a particularly low noise emission in the broadband frequency range caused by the leakage flow at the head gap due to a special design of the fan wheel in the radially outer region of the fan blades. The special design is achieved in particular by the fact that locally in the radial outer region of the course of the fan blades, seen in the spanwise direction, characterized by a significant deviation of the course in the spanwise direction in the remaining area of the fan blades. However, such a design of the fan can not or insufficiently reduce the tonal noise caused by Zuströmstörungen. Likewise, such a design can not or only insufficiently reduce the broadband noise in unprofiled wings and the trailing edge noise.

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

The present invention has for its object to design a fan so that it has lower noise emissions compared to the prior art. At the same time, it should be easy to design and manufacture. A corresponding fan and a system with a fan should be specified.

According to the invention the above object is achieved by the features of claim 1. With respect to the claimed fan, the above object is achieved with the features of the independent claim 1 1. With respect to the system, the problem is solved by the further independent claim 13. According to the invention, the fan wheel comprises at least two corrugated fan blades, the term "wavy" being to be understood in the broadest sense The figure description to Figures 1 to 3 illustrates what is meant by a wavy design of the respective fan blade It is an advantage of simple design and manufacture if the surface of the fan blade is not or hardly wavy on average, so that the waviness essentially refers to the leading edge of the blade and / or the trailing edge of the blade, a compromise between simple production and noise reduction Find. It is also conceivable that the waviness preferably extends over the entire fan blade surface, namely to effect a further-reaching noise reduction. Specifically, the waviness may preferably extend with the same or variable amplitude from the inner wing tip to the outer wing tip and from the wing leading edge to the wing trailing edge, these two edges are preferably formed wavy.

The ripple can be approximately sinusoidal, preferably with amplitudes in the range of 3 mm to 50 mm, depending on the dimensions of the fan blade. The amplitudes can be between 0.5% to 5% of the maximum fan diameter.

The outermost region of the fan blade of a fan wheel without bezel, i. the free end, can end with a negative sickle and possibly V position. Due to this special design, the broadband noise of the fan during operation can be reduced. This design achieves an effect comparable to that of a winglet. A fan blade can be made advantageous in the region of its inner and / or outer end at the transition to a hub ring or cover ring by the ripple. The design of the waviness can be achieved that a fan blade is at least partially at an angle of 75 ° to 105 °, preferably of about 90 °, to the hub ring or the cover ring, although the non-wavy reference wing under a much more acute or would dull to the hub ring or the cover ring would stand. This is advantageous for manufacturing, strength, aerodynamics and aeroacoustics.

From a manufacturing point of view and with regard to the costs, it is of particular advantage if the fan blade is manufactured in one layer from sheet metal (metal or plastic). The wavy design can be achieved in a fan blade made of sheet metal advantages in aerodynamics and aeroacoustics of the fan, similar to the advantages as they are much more expensive and expensive to realizing fan blades with cross sections similar to those of a wing profile can be achieved.

Fan blades with cross-sections similar to those of a wing profile can advantageously be designed wavy, with a casting technology production (plastic or metal) of fan blades or the complete fan wheel offers in the context of such a configuration.

The fan may be a radial / diagonal / axial fan or a diverter or idler.

The fan according to the invention comprises at least one fan wheel according to the preceding embodiments. It is also conceivable that the fan has at least one further, known per se known fan wheel according to the prior art. The combination of a fan impeller according to the invention with a conventional fan impeller may be advantageous, whereby a compromise with respect to the noise emission is to be accepted.

With regard to the system according to the invention, it should be noted that this is a system with at least one fan of the aforementioned kind, i. using at least one fan according to the invention, acts. Only examples are air conditioners or precision air conditioning units, compact air conditioning equipment, electronic cooling modules, generator ventilation systems for industrial and residential space, heat pump, etc. mentioned. It is essential for a system according to the invention that at least one fan according to the invention with at least one fan wheel according to the invention is used there.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand to the claims 1 and 1 1 subsequent claims and on the other hand to refer to the following explanation on the one hand, the wavy configuration of the fan and on the other hand preferred embodiments of the invention with reference to the drawings. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawings are also in the general explained common preferred embodiments and developments of the teaching. In the figures show

Fig. 1 to 3 are schematic representations to discuss the wavy configuration of the fan, in the concrete

Fig. 1 a is a schematic representation of a section through a

Radial fan to explain the definition of iso span surfaces,

1 b is a schematic representation of a section through a diagonal fan to explain the definition of iso-span surfaces,

Fig. 1 c is a schematic representation of a section through a

Axial fan to explain the definition of iso span surfaces,

2a is a schematic representation of a section of an iso span area with an unprofiled fan blade,

2b is a schematic representation of a section of an isospanned area with a profiled fan blade,

3 is a representation of functional curves for explaining the

Definition of the ripple of a function progression in the spanwise direction,

Fig. 4a is a perspective view of a Axiallüfterrads with wavy

Fan blades, the inner and outer ends of which have a special design,

Fig. 4b is a fan blade of Axiallüfterrads according to Fig. 4a, in axial

Viewing direction and seen in a plane section, 5a is a perspective view of a radial fan in sheet metal design with unprofiled, wavy fan blades, the wing surfaces are not wavy,

5b, the radial fan wheel according to Fig. 5a, viewed in the radial direction and in a planar section,

6a is a perspective view of a radial fan in sheet metal design with unprofiled, wavy fan blades, the wing surfaces are wavy,

6b, the radial fan of FIG. 6a, viewed in the radial direction,

6c, the radial fan wheel according to FIG. 6a, seen in the radial direction of view and in a plane section,

7a is a perspective view of a Nachleitrads (stator) with profiled, wavy fan blades, the wing surfaces are wavy in the vicinity of the leading edge of the wing, and

Fig. 7b, a fan blade of the Nachleitrads according to Fig. 7a, in radial

Viewing direction and seen in a plane section,

The definition of iso-span surfaces of a fan wheel will be explained with reference to FIGS. 1a, 1b and 1c, which in the following is the basis of the definition of the waviness of a fan blade. Iso-Spanflächenflächen are surfaces of rotation of certain curves, hereinafter referred to as IsoSpan n wide curves, which lie in a Meridionalebene to the associated fan axis. In particular, sections of such iso-span surfaces with fan blades are considered.

Figure 1 a shows a schematic representation of a fan 2 radial type in a plane through the Lüfterradachse 1, which corresponds to the axis of rotation. Such a level is commonly referred to as the meridional plane. The Fan wheel axis 1 is always aligned horizontally in the selected display. The exemplary radial fan consists essentially of a hub ring 4, a cover ring 5 and fan blades, which extend between hub ring 4 and cover ring 5. Hub ring 4 and cover ring 5 are in the embodiment of rotation body with respect to the Lüfterradachse 1. They are shown dotted in section through the plane of view, with only half of the hub ring 4 and 5 cover ring above the Lüfterradachse 1 is shown. The fan blades are shown in the form of their meridional fan blade surface 3a. The meridional fan blade surface 3a corresponds to the entirety of all points of the meridional section plane above the fan wheel axis 1, which lie at at least one arbitrary rotational position of the fan wheel 2 about the fan wheel axis 1 within a fan blade.

The meridional fan blade surface 3a has four edges 6, 7, 8 and 9. The inflow-side edge 6 and the downstream edge 7 represent the boundary of the fan blade surface 3a in the flow direction. The inner edge 8, which corresponds to the inner, hub ring-side end of the wing, as well the outer edge 9, which corresponds to the outer, cover ring-side end of the wings, represent the boundaries in the spanwise direction.

With the help of the inner edge 8 or of the outer edge 9, the innermost or the outermost iso-span curve 10 or 1 1 in the normalized span coordinate s = 0.0 or s = 1.0 defined. First, the edges 8 and 9 themselves are used as sections of the corresponding Iso-span curves 10, 1 1. Thus, the entire meridional fan blade surface 3a is within the general quadrilateral, which by the two iso-span curves 10 and 1 1 and the two straight sections 12 and 13, which respectively connect the two inflow-side and downstream endpoints selbiger Iso-span curves 10 and 1 1 is clamped, if necessary at the upstream and / or downstream end points of the two edges 8 and / or 9 still sufficiently long straight, tangential to the edges 8, 9 subsequent extensions attached, which then also part of the corresponding Iso Spannweitenkurven 10, 1 1 are. The straight line 12 is referred to as the inflow-side iso-meridional position curve, at which the origin for the meridional length position m is defined. The straight line 13 is referred to as the downstream iso-meridional position curve, at which the meridional length position m takes as value the length of the corresponding IsoSpan n wide curve from the straight line 12 to the straight line 13. The value of the meridional length position m at a point between the distances 12 and 13 corresponds to the length of the corresponding IsoSpan n wide curves from the straight line 12 to the point under consideration.

Iso span curves between the innermost and outermost iso span curves 10 and 1 1 are defined at each normalized span coordinate s between 0.0 and 1.0 by a linear combination of innermost and outermost iso span curves, where the linear combination is always for equal values of the meridional coordinate m is performed. FIG. 1 a shows an example 14 of an IsoSpan n wide curve at s = 0.7.

1 b shows a schematic representation of a fan wheel 2 of diagonal design in a meridional plane. The iso-span curves can be defined analogously to the comments on Fig. 1 a. In contrast to the example of Fig. 1a, an extension of the edges 8, 9 at the downstream end is necessary in this case, while in the example of FIG. 1 a, an extension of the edges 8,9 at the inflow end is necessary. Depending on the fan geometry, it may also be that no extension is needed, or an extension at both ends. Further, Fig. 1 c shows a schematic representation of a fan 2 axial design in a Meridionalebene. A bezel is not present in this example, the fan blade has an outer, free end. Again, the iso-span curves can be defined equivalent to the embodiments of Fig. 1 a or 1 b. The iso-span surfaces, which are always defined as surfaces of rotation of the iso-span curves around the fan wheel axis 1, in the example shown are cylinder jacket surfaces, which is a typical case for axial fan wheels. There are also fan wheel geometries, in particular with fan blades with free outer ends, in which the division of the edge of a meridional fan blade surface 3a in boundaries 6, 7, 8, 9 is not unique. In particular, an inner boundary 8 and / or an outer boundary 9 can not be unambiguously assigned to some geometries. In such cases, the division of the entire boundary of the meridional fan blade surface in finite long boundaries 6, 7, 8, 9 in the sense of the terms "inflow" and "downstream" for the boundaries 6 and 7 and "spanwise inside" and "in Spanwise direction "for the limits 8 and 9 are made intuitively. The definition of the iso-span curves is not unique, that is, for a fan geometry, there may be several definitions valid in the sense of the described invention. A wing is wavy in the sense of the invention, if for a valid definition of the Iso-Spannweitenkurven the definition made below the waviness applies.

In the same way, iso-span curves and iso-span surfaces can also be defined for stators (for example, pre- or idler wheels). FIGS. 2 a and 2 b show, by way of example and schematically, sections 16 of fan blades 3 with iso-span surfaces at any normalized span data s between 0.0 and 1.0. Such cuts are generally not on one level. In order to achieve the schematic representation in one plane, a conformal (angled) image is used, that is, the plotted angles in Figures 2a and 2b have the same magnitude as in the 3-dimensional section of the one-wing iso-span surfaces. All lengths of the cuts mean the actual lengths on the 3-dimensional cut surface. They are distorted by the image on the plane. FIG. 2 a shows schematically the section 16 of an unprofiled wing 3 with an iso span surface. In section, the 2-dimensional coordinate system 15 with the coordinate axes Θ and m at the origin (zero point) is located. Θ is a length coordinate in the circumferential direction of the fan wheel, and m is the already explained meridional coordinate. The origin (node) in terms of Θ is at the same angular position (same meridional plane) in the fan-wheel-fixed coordinate system for each span coordinate s. The origin (zero point) with regard to m is, as described in FIGS. 1 a - 1 c, in the inflow-side iso-meridional position curve 12.

The wing section 16 is significantly characterized by its imaginary center line 17. Superimposed on this centerline is a wing thickness d. In unprofiled wings 3, the thickness d is substantially constant over the meridional extent of the wing. In such fan blades, the thickness d is generally constant for all span data s. This makes it possible to manufacture the fan blades inexpensively from metal or plastic sheet. In the vicinity of the wing leading edge 18, the thickness d deviates in the example from the constant thickness, since the sheet metal wing is rounded there, which can bring advantages in the acoustics. In the vicinity of the blade trailing edge 19, the thickness profile has a taper, which can be achieved, for example, by reworking a sheet of constant thickness in order to reduce the trailing edge noise. Nevertheless, such a wing is referred to as un profiled sheet wing.

The mid-point 20 of the center line 17, which is measured at half the meridional extension of the center line 17 from the leading edge 18 of the wing, has the coordinates m _c and Q _c . With these coordinates, the displacement of the section in the meridional direction or in the circumferential direction is characterized. The section 16 has an extension I in the direction of the meridional coordinate m. At the leading edge of the wing 18, the center line 17 encloses an angle β1 with the circumferential direction. At the trailing edge 19, the center line 17 encloses an angle β 2 with the circumferential direction. The angles ß1 and ß2 are decisive for the aerodynamic and aeroacoustic properties of a fan wheel. The mean of the two angles is a measure of the stagger angle of the wing section 16, the difference of the two angles is a measure of the relative curvature of the wing section 16. The extent of the wing section 16 in the circumferential direction depends significantly on its extension I in the meridional direction and the stagger angle, that is, about the mean of ß1 and ß2, from. FIG. 2 b shows schematically the section 16 of a profiled wing 3 with an iso-span surface. It largely apply the comments on Fig. 2a. However, the thickness distribution is not constant. The thickness is rather a function of the meridional position m. In the embodiment, a thickness distribution is present, which is similar to that of a wing profile. There is at the wing section 16 a maximum thickness d _max . Such thickness distributions are characteristic of profiled fan blades 3. Profiled fan blades 3 are advantageous for efficiency and acoustics of a fan. However, the production of such fan blades is more complex than unprofiled blades, especially in a production of sheet metal. In the case of profiled wings, the thickness distribution and the maximum thickness d _{max can} additionally depend on the span coordinate s.

The wing sections 16 in FIGS. 2 a and 2 b cover the entire area from a wing leading edge 18 to a wing trailing edge 19 without interruption. Depending on the fan geometry and definition of the innermost and outermost iso span curve, it can be done in particular for normalized span coordinates s in the region of FIG Inner and / or outer IsoSpan n wide curves occur that a wing 3 is only partially cut, that is, that cuts 16 do not contain the entire area from a wing leading edge 18 to a wing trailing edge 19 without interruption. Such cuts 16 are defined as irrelevant for the definition of the waviness, and the range of the considered normalized span coordinates s is restricted for the definition of the waviness such that such incomplete cuts do not occur.

For the geometric sizes of a section 16 of a fan blade 3 with an iso span surface defined according to FIGS. 2a and 2b, the course for any fan blade 3 can be considered as a function of the normalized span coordinate s.

It is explained with reference to FIG. 3, when such a function profile is defined as wavy. Figure 3 shows a function curve 21 of any size, which, for example, SS1, SS2, I, m _c, 9 _C, SS1 -ß2, d _max, of the thickness d at a certain position m ^* in the meridional direction or another size of a Wing section may be, depending on the normalized span coordinate s. Obviously, the waveform of 21 is wavy. The likewise registered function course 22 tends to be similar to the function course 21, but is not wavy. It was derived by filtering the function curve 21. The filter used is the approximation of 21 by a polynomial of degree 3 with the least squares method in the relevant interval from s = 0.0 to s = 1.0.

Furthermore, the difference 23 from function course 21 and the filtered function course 22 is shown. With the help of the difference function 23, suitable definitions of ripple can be given. In particular, the difference function 23 has several extremes in the relevant interval from s = 0.0 to s = 1.0, advantageously more than 4 extremes. The difference function 23 has a plurality of zero crossings in this interval, advantageously more than 3. The differential function also has a plurality of inflection points, advantageously more than 3. Each of the criteria mentioned leads to the function course 21 to state that it is wavy. It can also be seen from this example that, if one assumes a non-wavy course of a function, one can arrive at a wavy course, one can additively superimpose the non-wavy with a suitable wavy function similar to the difference function.

With reference to FIG. 3, the wavelength λ and the amplitude A of a wavy function are defined. The wavelength λ is defined as the difference of the normalized span coordinate s between a zero crossing and the next zero crossing of the difference function 23, λ is a dimensionless wavelength, which is to be seen in relation to the normalized span coordinate s, which runs from 0.0 to 1.0 for the entire fan blade. Therefore, the number of waves over the span of a fan blade is about 1.0 / λ. Furthermore, a dimensioned wavelength Λ is introduced, which has the unit of a length, and in particular has the geometric distance of two successive wave peaks, measured in the spanwise direction, as the value. The amplitude A corresponds to the magnitude of the function value of an extremum of the difference function 23. λ, Λ and A are not constants, but can vary in the course of the difference function 23 or over a fan blade in a certain range. It is explicitly pointed out that the difference function does not necessarily have a similar course to a sine function. It may also have jagged, step-shaped, saw-toothed, comb-shaped, tongue-shaped or other progressions, as long as only the definition of waviness described above is fulfilled.

Generally, a fan blade is then called wavy spanwise when the course of at least one of the functions SS1, SS2, I, m _c, 9 _C, SS1 -ß2, d _max, SS1 + SS2 or d (m ^*) according to the made Definitions is wavy.

Fig. 4a shows a perspective view of a fan wheel 2 of axial design seen obliquely from behind. The fan blades 3 are wavy. The waviness of these fan blades 3 was achieved by superimposing the length coordinate O _c in the circumferential direction of a non-wavy reference blade with a sinusoidal waviness of the amplitude 10 mm. Advantageous amplitudes for ripples of length sizes are 3 mm to 20 mm. Based on the fan blade 3, this leads to a ripple of the sickle and the V-position. The waviness of the fan blades 3 can be clearly seen in the exemplary embodiment at a pronounced ripple of the wing leading edge 18 and the wing trailing edge 19. In this type of waviness, the amplitude, which is superimposed on the length coordinate O _c , can be found in approximately the same size even in the waviness of the leading edge 18 and the wing trailing edge 19. In Fig. 4b, which shows a fan blade 3 of the same fan wheel 2 in a sectional view, it can be seen that the ripple continues through the entire fan blades 3. The entire surface of the fan blade is wavy. There are approximately 4 ^Λ Α wavelengths over the entire spanwise extension of the fan blades 3. Advantageously, about 3 to 12 wavelengths extend over the entire spanwise extension of fan blades 3. In FIG. 4 b, the coordinate direction of the normalized span s, which is shown in FIG Section plane is located, marked. In addition, the dimensioned wavelength Λ is plotted in the spanwise direction at a point in the section. In the exemplary embodiment, this wavelength is about 3 cm at a maximum fan speed measuring 630 mm. Depending on the design, such wavelengths can advantageously be between 5 mm and 50 mm, or advantageously between 0.5% and 5% of the maximum fan diameter. The waviness of the wing leading edge 18 leads to a reduction in particular of the tonal noise, which arises as a result of Zuströmstörungen to a fan during operation. The waviness of the sickle in the example of Figures 4a and 4b aerodynamically provides a ripple of the lift coefficient. This waviness induces longitudinal swirls, which stabilize the suction-side wing flow and thereby reduce flow separation with concomitant noise generation. Due to the waviness of the wing trailing edge 19 noise generation mechanisms are attenuated by local separation areas or by the dull trailing edge geometry. Due to the waviness of the wing surface emerging and reflected noise is more scattered on the wing, which leads to advantages in the noise behavior of the fan. By the simple measure of the superposition of the longitudinal coordinate Q _c in the circumferential direction with a ripple, the acoustic behavior of a fan at several causal mechanisms can be improved. Particularly advantageous embodiments of the ripple can also be seen in Figures 4a and 4b. On the one hand, the outermost region 26 of the axial fan blade 3 is designed in a very targeted manner with the aid of the waviness. In this area, the fan blade 3 ends with a magnitude high, negative sickle and V position. The outermost wing sections are locally shifted strongly against the direction of rotation. Such a design has a massive reducing effect on the broadband noise, which is often a significant source of sound due to the Kopfspaltüberströmung in an axial fan. In this respect, the exemplary design takes over the aeroacoustic function of a winglet. It can also be said that winglets and ripples have been perfectly and seamlessly integrated into each other with a single constructive measure.

Even in the innermost region 25 of the fan blade 3, a very targeted design has been made. Thus, as can be seen in Fig. 4b, the fan blade 3 hits locally at an approximately right angle to the hub ring 4. This brings decisive advantages in joining processes between hub ring 4 and fan blades 3, especially when welding. Also, for the manufacturing process of plastic injection molding in the integral production of a fan 2, such a design is of particular advantage. Furthermore, the notch stresses on the blade root are minimized by such a design. The impact of the fan blades 3 at an approximately right angle, preferably about an angle of 75 ° to 1 15 °, on the hub ring 4 is achieved by the ripple. The non-wavy reference wing, which has comparable aerodynamic properties (efficiency and air performance), would impinge on the hub ring 4 at a significantly more acute angle.

Fig. 5a shows a perspective view of a fan wheel 2 radial design obliquely from the front. The fan blades 3 are wavy. The waviness of these fan blades 3 is expressed, in particular, in a waviness of the variables m _c (position of the blade section in the direction of the meridional coordinate) and Q _c (position of the blade section in the direction of the circumferential length coordinate). The extension I of the cuts in the meridional direction is not wavy. Other sizes can also have a less pronounced ripple. The waviness is found in the course of the leading edge 18 and the wing trailing edge 19 again. This reduces leading edge noise due to flow disturbances and trailing edge noise. In the example, there are about 7 Vi wavelengths over the entire span. The dimensioned wavelength Λ tends to be greater in the area of the leading edge 18 than at the trailing edge 19, which is due to the fact that the wing leading edge 18 over the entire span is significantly longer than the wing trailing edge 19 as a result of its course.

From Fig. 5b, which shows the subject of Fig. 5a cut in a radial view, it is clear that the ripple in this embodiment is selected so that the surface of the fan blades 3 seen in section is not wavy. In particular, in interaction the waviness of m _c and Q _c and other variables is chosen such that this surface, seen in section, is not wavy. This leads to a slight reduction of the acoustic advantages due to the ripple, but has manufacturing advantages. It is in the fan 2 in this example to a fan with unprofiled fan blades. 3 The thicknesses d of the fan blades 3 are essentially constant, as can be seen in the planar section 24 of a fan blade 3 in FIG. 5b. Such a fan is advantageously made of sheet metal (metal or plastic). The production of fan blades 3 made of sheet metal is much easier and cheaper if the surface of the fan blades 3 seen in section is not wavy, since the deformation energy required when embossing or deep drawing of the sheet metal blades in this case is much lower. The waviness of the front and rear edges, which alone brings great acoustic benefits, manufacturing technology can be realized for example by trimming or punching.

Fig. 6a shows a perspective view of a fan 2 radial type seen obliquely from the front. The fan blades 3 are wavy. The fan 2 in the embodiment is similar to that of the embodiment of FIG. 5a, 5b. In particular, the non-wavy reference vanes are of the same geometry. However, the waviness of these fan blades 3 in this embodiment differs from the previous one. It is expressed in particular in a ripple of size (ß1 + ß2) / 2, ie in particular a ripple of the staggering angle. The geometric deflection (β1 -β2), the coordinates Q _c and m _c and the meridional extent I of the fan blades 3 are not wavy over the spanwise direction. The amplitude A of the waviness of (β1 + β2) / 2 is about 1 °. The amplitudes of ripples of angular sizes are advantageously 0.5 ° - 3 °. In FIG. 6 a, it can be seen that, caused by the described ripple, in particular the courses of front edge 18 and rear edge 19 of the fan blades 3 have a pronounced waviness, which leads to the already described acoustic advantages.

FIG. 6b shows a radial side view of the article from FIG. 6a. The waviness of the wing trailing edges 19 is different strong recognizable depending on the viewing direction. Since m _c and I are not wavy, the position of the blade trailing edges 19 in the meridional direction is not wavy. This can be reconstructed, for example, in the wing trailing edge 19 located at the bottom in FIG. 6b. However, the waviness of (.beta.1 + .beta.2) / 2 leads to a waviness of the position in the circumferential direction of the blade trailing edges 19. In FIG. 6b, this is particularly pronounced in the blade trailing edge 19 located approximately in the center of the image. The amplitude A This trailing edge ridge waviness is preferably 3 mm to 20 mm, or 0.5% to 5% of the maximum fan diameter. The description of the course of the wing trailing edges 19 also applies to the course of the wing leading edges 18 in the exemplary embodiment.

In Fig. 6b also the particularly advantageous design of the inner and outer regions 25 and 26 of the fan blades 3 of the fan blade 2 made of sheet metal can be seen. Due to the special configuration of the waviness in the inner region 25 or in the outer region 26 of the fan blades 3, it has been achieved that the surface angle which the hub ring 4 or the cover ring 5 encloses with fan blades 3 at the connection region is close to 90 ° over a wide range , This is very advantageous for manufacturing, especially when welding of metal wheels and the injection molding of complete fan wheels. In radial fan wheels in the intersection of the cover ring 5 and wing leading edges 18, this property is particularly advantageous for the acoustics. This squareness has been achieved, although there are angles for the aerodynamic and efficiency optimized pre-emption characterized by the non-wavy reference fan blade that are significantly more acute or blunt. A particularly advantageous design of the ripple is achieved when the largest and / or average magnitude deviation of 90 ° between fan blades 3 and hub ring 4 and cover ring 5 has been reduced by the ripple by at least 10 °.

FIG. 6c shows, in a plane section, the object from FIGS. 6a, 6b, viewed radially from the side. Even in the plane sections 24 of the wings, a ripple is recognizable. In this embodiment, therefore, the surface of the fan blades 3 is wavy. This leads, as already described, to additional acoustic advantages. However, the production method in sheet metal is more difficult. The application of a relatively high deformation energy for embossing or deep drawing of the fan blades is necessary, in particular in order to introduce the wavy contour. In addition, it must be ensured that the sheets do not break during such a deformation process. Special flowable metal or plastic sheets can be used. A decisive measure of the deformation energy to be applied is the local wave amplitude A of the displacement of the wing surface due to the Waviness relative to its non-wavy reference position with respect to the dimensioned wavelength Λ. In order to achieve good acoustic effects and still obtain finished sheet metal blades, a ratio Α / Λ in the range between 0.03 and 0.3 has proven to be particularly advantageous.

The waviness of the fan blades 3 in the example of Fig. 6a-6c has the peculiarity that seen in the meridional direction in the region of the center of the wing sections, so seen in the meridional direction approximately in the middle of the fan blades, no or little ripple appears pronounced (there appears in the Section seen the amplitude of the ripple zero or near zero). At the lower wing section 24 in Fig. 6c, such a central region is approximately cut, which is why there the appearance of the ripple appears relatively low. This is due in particular to the fact that neither m _c nor Q _c are superimposed with a ripple. This design is particularly advantageous in fan blades 3 in sheet metal construction. On the one hand, the strong characteristic of the waviness is limited to the areas that are most important with regard to the formation of noise in the vicinity of the leading edge 18 and the trailing edge 19 of the wing. In the less important area in the fan blade center, viewed in the meridional direction, unnecessary deformation effort is largely avoided. Furthermore, the rather not or only slightly wavy central region has significant advantages in terms of the deformation of the fan blades 3 in operation. Due to the presence of this region, in particular deformations in the spanwise direction and approximately perpendicular to the surface of the fan blades can be significantly reduced. Fig. 7a shows a perspective view of a fan 2, which is a non-rotating in operation Nachleitrad (stator), seen from obliquely from the front. The fan 2 has a hub ring 4 and a cover ring 5, which are interconnected by wavy fan blades 3. At the hub ring 4, a mounting flange 28 is provided for a motor. On the cover ring 5, a fastening portion 29 is provided, with which the Nachleitrad 2 can be attached, for example, to a housing. The ripple in this embodiment has been constructed by a ripple of the local vane thickness d at a meridional position m ^* near the vane leading edge 18. Both wing leading edge 18 as well Wing trailing edge 19 are not wavy. In Fig. 7a, the waviness of the fan blades 3 can be recognized by the waviness of some view silhouettes 31.

Fig. 7b shows, seen from the front, the object of Fig. 7a in a section on a plane perpendicular to the axis of rotation, wherein the axial position of the cutting plane in the vicinity of the wing leading edge 18 is located. In the sections 24 by wing 3, the waviness of the thickness is very clearly visible. There are about 9 wavelengths of waviness of the local thickness d over the spanwise direction. The maximum amplitude of this ripple is about 4 mm. Such an embodiment is advantageously made in cast due to the non-constant thickness of the fan blades 3. The fan blades 3 are then advantageously profiled, as in the embodiment. The waviness of the thickness of the fan blades 3 in the vicinity of the leading edge 18 leads to a reduction of the tonal noise due to inflow disturbances (leading edge noise). In this respect, a comparable effect is achieved as in a wavy design of a wing leading edge 18.

With regard to further advantageous embodiments of the fan according to the invention reference is made to avoid repetition to the general part of the specification and to the appended claims.

Finally, it should be expressly pointed out that the above-described embodiments of the fan impeller according to the invention are merely for the purpose of discussing the claimed teaching, but do not restrict it to the exemplary embodiments.

C o m p a n c e m e n t i o n s

1 fan wheel axis

2 fan wheel

3 fan blades

3 a meridional fan blade surface

4 hub ring

5 cover ring

6 inflow-side boundary

7 Outflow boundary

8 inside boundary

9 Outer limit

10 innermost iso span curve

1 1 Extreme iso-span curve

12 Inflow-side iso-meridional position curve

13 Downstream iso-meridional position curve

14 Example of an Iso span curve at s = 0.7

15 Two-dimensional coordinate system (9, m)

16 Section of a wing with an iso span curve

17 midline

18 wing leading edge

19 wing trailing edge

20 midpoint of the midline

21 Wavy function

22 Filtered function

23 difference function

24 plane section of a wing

25 Inner area of a grand piano

26 Outer area of a grand piano

27 direction of rotation

28 Motor mounting flange

29 Housing mounting area

30 inlet nozzle of a stator 31 Silhouette line of a fan blade

Claims

1. Fan for one fan, with at least two wavy fan blades.

2. fan according to claim 1, characterized in that the surface of the fan blade in any, over the span extending planar section is not or hardly wavy, so that the ripple refers essentially to the Flügelvorder- and wing trailing edge.

3. fan wheel according to claim 1, characterized in that the surfaces of the fan blades seen in at least one over the span extending planar section having a ripple, which preferably extends over the entire fan blades.

4. Fan according to one of claims 1 to 3, characterized in that the ripple is approximately sinusoidal, with ripples of length sizes preferably with amplitudes in the range of 3 mm to 50 mm and / or between 0.5 and 5% of the maximum fan diameter and for ripples of angular sizes, preferably with amplitudes in the range of 0.3 ° to 3 °.

5. fan according to one of claims 1 to 4, characterized in that no cover ring is present and the outermost region of the fan blade (the free end) ends with a negative sickle and possibly V position.

6. fan according to one of claims 1 to 5, characterized in that the inner and / or outer region of the fan blade (a hub ring or on the cover ring fixed end) at an angle of 75 ° to 105 °, preferably of about 90 ° , to the hub ring is, with the non-wavy reference wing, the ensprechende angle is much sharper or dull, that is not in the said range.

7. Fan according to one of claims 1 to 6, characterized in that the fan blades made of sheet metal (metal or plastic) is made.

8. Fan according to one of claims 1 to 6, characterized in that the complete fan is cast (metal or plastic) made.

9. Fan according to one of claims 1 to 8, characterized in that it is designed as a radial / diagonal / Axiallüfterrad or as Vorleit- or Nachleitrad.

10. fan with at least one fan wheel according to one of claims 1 to 9.

1 1. A fan according to claim 10, with at least one further, known per se known fan wheel according to the prior art.

12. System having at least one fan according to one of claims 10 or 11, wherein the system is, for example, a (precision) air conditioning unit, a compact / air conditioning box unit, an electronic cooling module, a generator ventilation system, an industrial or residential refrigerator, a heat pump , etc. can act.