EP3561309B1 - Fan, method for its construction and method for dispensing a medium - Google Patents

Description

Fan, method for its construction and method for dispensing medium The present invention relates to the field of sucking in gaseous medium and its pressurized discharge and in particular to the field of fans such as centrifugal fans, axial fans and diagonal fans. U.S. 2,238,749 discloses a fan having a plurality of fan blades, in each of which different deformations or deformations are alternately provided with no deformations at the trailing edge in order to reduce noise.

DE 10 2009 028 125 A1 discloses a fan with a fan wheel which comprises suction blades extending in the radial and axial direction with a leading edge facing an axial inlet direction of the fan wheel, at least one suction blade having a swirl device for generating microturbulence in the area of its leading edge.

DE 20 2010 018 509 U1 discloses a fan wheel in a design as a radial or diagonal fan, consisting of a cover disk with an inlet opening, a bottom disk and several fan blades distributed over the circumference of the inlet opening and around an axis of rotation as well as with blade channels formed in the circumferential direction between the adjacent fan blades, which lead radially or diagonally outward from the area of the inlet opening and form blow-out openings in the outer area, the blade channels being designed to be so large in terms of their effective flow cross-section that a turbulent flow with a Reynolds number significantly greater than 2300 is achieved during operation, and the cover disk and / or the bottom disk have / has a non-rotationally symmetrical geometry, the respective non-rotationally symmetrical geometry having a continuous, point-continuous course viewed in the axial or axially parallel direction.

US 2012/321495 A1 discloses a centrifugal fan in an electronic device cooling system with asymmetrical blade spacing with acceptable balance. The asymmetrical blade spacing is determined according to a set of desired acoustic artifacts that are favorable and a balance similar to that for the same fan blade spacing. In one embodiment, the fan impeller may include sixty-one fan blades.

A starting point of the present invention is explained below with reference to an exemplary application of a radial fan for cooling converters by means of an air flow.

It has been found that when radial fans are used with many converter variants, an unpleasant noise occurs during operation, which is due to a so-called rotating sound.

beschreiben, wobei f_D die Grundfrequenz des Drehklangs, n die Drehzahl und z die Schaufelzahl ist.By passing each individual radial blade on surrounding components such as housing walls, a single impulse is generated which, through its harmonious recurrence, generates a rotating tone or rotating sound. This can be clearly seen in the frequency spectrum and can be expressed using the formula $f_{\mathrm{D.}}=\frac{n\times z}{60}$

describe, where f _{D is} the fundamental frequency of the rotating sound, n is the speed and z is the number of blades.

169,16 Hz ≅ 170 Hz). Eine derartige Frequenz und ihre Harmonischen haben einen großen Einfluss auf den vom menschlichen Ohr wahrgenommenen Ventilatorton.With a fan impeller with seven blades and a speed of 1450 min ^-1 , a fundamental frequency of the rotating sound of approx. 170 Hz is to be expected $(f_{\mathrm{D.}}=\frac{1450\times \mathrm{7th}}{60}\frac{1}{\mathit{min}}=$

169.16 Hz ≅ 170 Hz ). Such a frequency and its harmonics have a great influence on the fan sound perceived by the human ear.

The above problem is addressed by way of example for the case of a radial fan, the same also applying, for example, to axial fans and diagonal fans.

In order to avoid disruptive perception when a fan is in operation and also to generally satisfy sound immission aspects, insulation measures have been taken up to now, which entail additional effort and thus additional costs.

It is an object of the present invention to provide a fan, a method for its construction and a method for the pressurized delivery of gaseous medium, in which the problems occurring with known solutions are avoided or at least reduced.

It is therefore desirable to present a solution in which, for example, disruptive noises / frequency ranges occur to a reduced extent, without having to provide separate insulation measures or the like for this purpose.

According to the invention, a fan as defined in claim 1 is proposed according to first aspects.

According to the invention, a method for constructing a fan as defined in claim 8 is proposed according to second aspects.

According to the invention, according to further aspects, a method for the pressurized delivery of gaseous medium is proposed, as is defined in claim 9.

Part of the background to the present invention resides in the following considerations.

It has been found that a design change, for example the blade angle and the outer contour of the blade (trailing edge), can be used to create an asymmetry that eliminates or disrupts the harmonic propagation of the speed after leaving the radial impeller. Regardless of the fluid dynamic asymmetry of the impeller geometry, a mechanical symmetry to the center of gravity can be maintained, which means in detail that balancing is subject to similar or even the same conditions as with a known fan impeller. It can also be assumed that with a corresponding impeller geometry, no relevant negative changes can be identified with regard to strength and vibration characteristics. The reduction in the vibration excitation of the components located in the vicinity generated by the aeromechanical excitation also has the advantage that these components are therefore exposed to lower loads.

The specifically provided asymmetry thus allows an improved noise behavior, which is due to the fact that the respective individual impulses of the individually designed blades differ from one another, so that the rotational sound occurring in known solutions is to a certain extent "smeared" in its frequency spectrum.

The asymmetry mentioned above is already given when two impellers differ in one of the properties that influence the media impulse exerted by the respective impeller on a component of the fan during operation. This can mean that with regard to this property, all but one of the airfoils are identical, that is to say that this one of the airfoils differs from all of the other airfoils in this property. The difference between two paddle wheels can also be connected with the fact that, regardless of this difference, there are one or more pairs of paddle blades (which do not necessarily have to be arranged adjacent to one another in order to be viewed as a pair in this sense), each of which has at least one difference is present in one of the properties. However, it is provided according to the invention that each airfoil differs from every other airfoil both in the contour and / or inclination of its trailing edge and in its offset with respect to a rotational symmetry.

Preferably, the asymmetry includes that when the rotating element is imagined to be rotated by one or two fractions of a full revolution corresponding to the number of blades, the rotating element is rotated with regard to at least one property of an blade that influences the operation of the respective blade a component of the fan has media impulse exerted, differs from the rotating element that is not rotated. In other words, the design of the airfoil cannot be mapped onto itself by rotating one or two angular sections between two adjacent airfoils. In a case of a conventional, symmetrical impeller with six identical blades, which are arranged at equal intervals, an image on itself results for every (imaginary) rotation of 60 °. In the case of a fan according to the invention, only one full (imaginary) revolution preferably results in the rotating element being mapped onto itself.

It should be noted here that the considerations and features presented here apply to every type of fan, even if the present invention is primarily described and illustrated using the example type of a radial fan. It should be clear to the person skilled in the art that the explanations in each case apply directly or in an analogous manner to other types of fans, so that the invention is not to be understood as being limited to radial fans.

According to the invention, the property that has an influence on a media pulse exerted by the respective blade during operation on a component of the fan includes a contour and / or inclination of a trailing edge of the blade, and an offset of an arrangement of the blade with respect to a rotational symmetry of the rotating element given output arrangement, the rotational symmetry corresponding to a number of blades of the rotating element.

In an advantageous embodiment of an aspect of the invention, the property which has an influence on a media pulse exerted by the respective blade during operation on a component of the fan includes, a contour and / or inclination of a leading edge of the airfoil, and / or a surface contour of the airfoil.

The surface contours of an airfoil are already modified in known solutions with respect to a comparatively simply curved surface. In contrast to the present invention, however, it is provided here that all of the airfoils are modified in the same way, for example by providing depressions, raised areas, deviations in curvature and the like. Insofar as the surface contour is part of the property or property group that deviate from one another in at least two blades within the scope of the invention, this deviation can also consist in the fact that one of the blades has a well-known surface contour without modification, while the other blade or blades have modified surface contours have, as consist in the fact that the affected blades each have their own, differing modifications.
In known arrangements of fan blades, there is a rotational symmetry corresponding to the number of blades, so that, for example, a cross section of a fan with six blades coincides again with a rotation of 60 ° about the axis of rotation. The arrangement here includes in particular the actual position of the airfoil, that is to say also the orientation of the airfoil.
It is assumed that - in addition to the alignment and positioning of the airfoil - the contour of the trailing edge of the airfoil has a particularly strong influence on the media impulse caused by passing this edge on a component of the fan. It was found that, in addition to the contour, the inclination of this edge can also be used as a property to be varied. In known radial fans, for example, the outflow edges are arranged parallel to the axis of rotation. An inclined position of the discharge cross section results in a delay in the angle of impact the current. The inclination - with a modified contour of the edge, possibly averaged over the extension of the edge - is preferably in a range from 5 ° to 15 °, particularly preferably in a range from 8 ° to 12 °.

Similar to the trailing edge, the airfoil can also be differentiated in the leading edge.

In a preferred variant of the above embodiment, the property that has an influence on a media pulse exerted by the respective blade during operation on a component of the fan comprises the contour of the trailing edge of the blade, with the at least two blades differing in terms of a deviation in the contour of their respective Differentiate the trailing edge from a given exit trailing contour.

As a given exit outflow contour, i.e. as a reference for quantifying a deviation or differentiation between blades, a linear edge with a straight course parallel to the axis of rotation can be assumed in a radial fan, possibly also an inclined linear edge. It should be noted here that the exit outflow contour only serves as a benchmark, without such an exit outflow contour having to have been present, for example, during the manufacture of the airfoil. The initial contour is, however, not limited to a linear shape, in particular in view of the blade-blade contours that predominate in the respective fan designs.

In a further preferred variant of the above embodiment, the property that has an influence on a media pulse exerted by the respective blade during operation on a component of the fan comprises the contour of the leading edge of the blade, with the at least two blades differing in terms of a deviation in their contour differentiate the respective leading edge from a given exit entry contour.

The same applies to the above statements on the trailing edge for the leading edge.

In a further preferred variant of the above embodiment, the deviation of the contour of the trailing edge and / or the leading edge of at least one airfoil from the exit trailing contour or the exit inflow contour varies over the extension the trailing edge or the leading edge, a maximum deviation in one direction being at least 1/150 of the airfoil length and a maximum deviation in a direction opposite to the direction being at least 1/150 of the airfoil length.
The deviation of the contour of the edge (s) can in turn be regular (for example in the form of a wavy line or zigzag shape), although an irregularity is preferred. The size of the deviation is provided in such a way that there is a relevant effect on the media pulse, so that a microscopic roughness (e.g. caused by production) of the edge is not yet to be understood as a deviation.
In a preferred variant of the above embodiment, the maximum deviation in the direction is less than 1/15 of the airfoil length and the maximum deviation in the opposite direction is less than 1/15 of the airfoil length.
The contour preferably deviates from the initial contour, which is used as a reference, in such a way that the maximum deviation lies in the range determined by the above values. Particularly in the case of an irregular configuration of the edge (s), it can be provided that the deviation from an inclined starting contour tends to zero on average.

In a further preferred variant of the above embodiment, the offset of the arrangement comprises an orientation and / or a positioning of the blade.
An arrangement of the blades that breaks the symmetry can also influence the media impulses in the desired manner, which are caused by the blades when they pass through another component of the fan. Here, an arrangement of a blade can be changed compared to a (conceptually assumed) conventional arrangement, for example in the case of a radial fan, on the one hand by rotating the blade about an axis that is parallel to the axis of rotation, i.e. deviates in its orientation. Another change can be described by the fact that the airfoil in the Impeller of the radial fan defined level is arranged offset. The offset in the plane and a change in the orientation are preferably combined with one another.

According to the invention, each airfoil of the plurality of airfoils differs from every other airfoil of the plurality of airfoils in a contour and / or inclination of the trailing edge of the airfoils.

The more respective deviations there are between the blades, the greater the "smearing" of the rotary sound over a broad spectrum, so that the corresponding tone becomes less perceptible.
In another advantageous embodiment of an aspect of the invention, the fan is a radial fan or a diagonal fan and the rotating element comprises a support disk and / or a cover disk, an outer contour of the support disk and / or the cover disk having a deviation that varies over the circumference compared to a circle , with a maximum outward deviation of at least 1/150 of the disk diameter and a maximum inward deviation of at least 1/150 of the disk diameter.
On the one hand, it was found that, in addition to the blades, the support disk and the cover disk of a radial fan impeller also contribute to the rotary sound, so that the invention here can include influencing the rotary sound by appropriately designing the contour. On the other hand, by adapting the cover disk and / or the support disk, compensation for an imbalance of the blade arrangement that occurs due to deviations of the blade blades from one another can be achieved.

The differences with regard to the trailing edge and the arrangement are dimensioned such that a center of mass of the rotating element coincides with an axis of rotation of the rotating element.
The variations of the dimensioning used for this, that the center of gravity of the rotating element coincides with the axis of rotation (i.e. that no imbalance occurs), are not due to the previously mentioned deviations, for example of the blades limited against each other. For example, variations can also be provided that have little or no effect on the rotary sound, for example the material thickness of the blades (in comparison of blades with one another or within a blade)

Features of advantageous embodiments of the invention are defined in the subclaims.

Fig. 1

eine schematische Darstellung eines Radialventilators zur Illustration einer Geräuschentwicklung im Betrieb.

Fig. 2

eine schematische Seitenansicht eines Laufrads als einem Aspekt einer ersten erfindungsgemäßen Ausführungsform eines Ventilators.

Fig. 3

Ansichten von Schaufelblättern des Laufrads, das in Fig. 2 illustriert ist.

Fig. 4

weitere Ansichten des Laufrads, das in Fig. 2 illustriert ist.

Fig. 5

zu Fig. 4 vergleichbare Ansichten eines herkömmlichen Laufrads.

Fig. 6

eine Abströmkante eines Schaufelblatts eines Ventilators gemäß einer erfindungsgemäßen Ausführungsform im Detail und im Vergleich zu einem herkömmlichen Schaufelblatt.

Fig. 7

eine Aufsicht auf eine Tragscheibe eines Laufrades einer erfindungsgemäßen Ausführungsform eines Ventilators.

Fig. 8

ein Laufrad einer erfindungsgemäßen Ausführungsform eines Ventilators mit der Tragscheibe aus Fig. 7.

Fig. 9

ein Schaufelblatt gemäß einer weiteren Ausführungsform eines erfindungsgemäßen Ventilators.

Fig. 10

das Schaufelblatt aus Fig. 9 in einem Einbauzustand in einem Laufrad.

Fig. 11

Ansichten einer Deckscheibe einer Ausführungsform eines erfindungsgemäßen Ventilators.

Fig. 12

eine Ansicht eines Laufrads mit der Deckscheibe aus Fig. 11.

Fig. 13

eine weitere Darstellung des Laufrads, das in Fig. 2 illustriert ist.

Fig. 14

schematisch ein Ablaufdiagramm, das eine Ausführungsform eines erfindungsgemäßen Verfahrens zur Konstruktion eines Ventilators illustriert.

Fig. 15

schematisch ein Ablaufdiagramm, das eine Ausführungsform eines erfindungsgemäßen Verfahrens zur druckbeaufschlagten Abgabe von gasförmigem Medium illustriert.

In the following, the present invention is further illustrated and explained on the basis of the exemplary embodiments shown in the figures. Here shows

Fig. 1

a schematic representation of a radial fan to illustrate noise development during operation.

Fig. 2

a schematic side view of an impeller as an aspect of a first embodiment of a fan according to the invention.

Fig. 3

Views of blades of the impeller in Fig. 2 is illustrated.

Fig. 4

further views of the impeller that is shown in Fig. 2 is illustrated.

Fig. 5

to Fig. 4 comparable views of a conventional impeller.

Fig. 6

a trailing edge of an airfoil of a fan according to an embodiment of the invention in detail and in comparison with a conventional airfoil.

Fig. 7

a plan view of a support disk of an impeller of an embodiment of a fan according to the invention.

Fig. 8

an impeller of an embodiment of a fan according to the invention with the support disk Fig. 7 .

Fig. 9

a blade according to a further embodiment of a fan according to the invention.

Fig. 10

the blade off Fig. 9 in an installed state in an impeller.

Fig. 11

Views of a cover plate of an embodiment of a fan according to the invention.

Fig. 12

a view of an impeller with the cover plate from Fig. 11 .

Fig. 13

another representation of the impeller, which is shown in Fig. 2 is illustrated.

Fig. 14

schematically a flowchart illustrating an embodiment of a method according to the invention for constructing a fan.

Fig. 15

schematically a flowchart illustrating an embodiment of a method according to the invention for the pressurized delivery of gaseous medium.

In the accompanying drawings and the explanations of these drawings, elements that correspond or are related to one another are identified - as far as appropriate - with corresponding or similar reference numerals, even if they are to be found in different exemplary embodiments.

Fig. 1 shows a schematic representation of a radial fan to illustrate noise development during operation. Figures 1a and 1b show the velocity profile in the casing and after the blade outlet.

Fig. 2 shows a schematic side view of an impeller as an aspect of a first embodiment of a fan according to the invention. The fan is a radial fan, the impeller 10 having a support disk 12 and a cover disk 14, between which blades 16a, 16b, 16c, 16d, 16e are attached. The person skilled in the art is familiar with the basic complexity of an impeller and also the other elements of a fan (here radial fan), so that no further explanation is necessary in this regard.

Since the representation of Fig. 2 the impeller 10 shows from the side, not all of the blades can be seen.

The blades each have a trailing edge 16a ', 16b', 16c ', 16d'.

Fig. 3 illustrates views of blades of the impeller shown in Fig. 2 is illustrated. The airfoils 16a-16g point to the one shown in FIG Fig. 3 left side the respective trailing edge 16a'-16g '. The edges facing the support disk and the cover disk (not shown here) are of conventional design. In this embodiment, the leading edges 16a "-16g" (each in the illustration of FIG Fig. 3 right) conventionally executed.

In Fig. 3 it can be seen that the trailing edges 16a'-16g 'of the airfoils 16a-16g each have a contour which differs for each trailing edge from all trailing edges of the other airfoils. In other words, all trailing edges 16a'-16g 'are different from one another in pairs.

The difference here is that the contours are different in an order of magnitude above (preferably significantly above) inherently unavoidable fluctuations in a component geometry (on a sufficiently small scale, differences can always be identified for otherwise supposedly identical components, in particular due to the manufacturing process) that, for example, when the contour lines of two trailing edges are superimposed, these lines cannot, or at least not completely, be brought into congruence. In the context of the present invention, the contour can preferably be designed so that the edge from the support disk to the cover disk represents random or at least pseudo-random projections or recesses in relation to an imaginary "center line" within the scope of the continuity of the edge. It can, however, also be provided that an edge profile can be described by a rule or a mathematical function, in which case, however, all blade edges still differ from one another, either by applying different rules or functions and / or by applying different parameters for one same rule or function.

Fig. 4 Illustrated further views of the impeller shown in Fig. 2 is illustrated. Figure 4a shows a top view of the impeller 10 with the cover disk removed, so that the position and orientation of the blades 16a-16g on the support disk 12 can be seen.
As a result of the respectively different contours of the trailing edges 16a'-16g 'of the airfoils 16a-16g, the airfoils also have a mass distribution that differs from one another. In order to nevertheless achieve that the center of mass coincides with the axis of rotation of the impeller 10 in a manner sufficient for a person skilled in the art (i.e. the impeller 10 has no imbalance or at most a negligible or permissible imbalance), the blades 16a-16g are each essentially perpendicular a plane defined by the support disk and a respective outer end at corresponding interval positions each pivoted about an axis parallel to the axis of rotation of the impeller 10, so that the center of gravity of the impeller 10 (then with cover plate 14) is at a desired position.

The design of the contour of the trailing edge 16a "-16g" and the arrangement of the respective airfoil are related to one another. In order to avoid mixing up components during assembly, it can be provided that the blades 16a-16g and the support plate 12 (or the cover plate 14 if the blades are to be attached to the cover plate 14 first) are coded with one another. This can be achieved, for example, in that the blade blades have clearly arranged and / or combined extensions and the support disk is provided with suitable slots for receiving the extensions at the corresponding positions (see also Fig. 7 ).

Fig. 5 shows to Fig. 4 comparable views of a conventional impeller. In the representation of Figure 5a it can be seen that the conventional impeller has a symmetry with respect to a rotation of 60 °. The same applies to Figure 5b .

Fig. 6 shows a trailing edge of an airfoil of a fan according to an embodiment of the invention in detail and in comparison with a conventional airfoil.

This in Figure 6a The blade 16 shown, which is arranged between the support disk 12 and the cover disk 14 of the rotating element of the fan, has a trailing edge 16a 'which initially extends from a corresponding trailing edge of an airfoil of a conventional fan ( Figure 6b ) differs by its irregularity. In addition, a center line 18, which represents a straight averaging of the contour of the trailing edge 16a 'from its contact with the support disk 12 to its contact with the cover disk 14, compared to a vertical connection between support disk 12 and cover disk 14 (parallel to the axis of rotation of the impeller) is inclined. Even if it can be provided that this center line and the contour coincide with one another at the respective ends, this feature is not necessary for the invention.

Fig. 7 shows a plan view of a support disk of an impeller of an embodiment of a fan according to the invention.

The support disk 12 'of this embodiment has an irregular circumference, which is shown in FIG Fig. 7 is illustrated in comparison to an approximately circular perimeter 20. On the basis of this regular circumference 22, the irregularity of the support disk 12 'can be easily recognized. Such a design of the outer contour of the support plate 12 ' leads to the fact that a media impulse caused by the support disk 12 'during the rotation of the impeller with this support disk loses continuity and / or regularity, so that less disturbing noises are produced.

In the representation of Fig. 7 In addition, mounting slots 20 provided in the support disk 12 'can be seen, which are used to accommodate corresponding extensions of the blades during the assembly of the impeller, whereby these mounting slots 20, with a corresponding arrangement, extension and / or shape, can serve to ensure that the blades are only in one can be mounted in a predetermined manner and arrangement. In this way it can be avoided, for example, that an imbalance is introduced into the impeller by mistakenly interchanging two irregular blades.

Fig. 8 shows an impeller of an embodiment of a fan according to the invention with the support disk from FIG Fig. 7 . In Fig. 8 the support disk 12 'as part of an impeller 10' together with blades is comparable to Fig. 2 and Fig. 3 and a cover plate 14 is shown.

Fig. 9 illustrates a blade according to a further embodiment of a fan according to the invention. The airfoil 16h is similar to the airfoil 16a-16g discussed above, with an irregularly shaped contour of a trailing edge 16h 'and projections 24 (matching the corresponding assembly slots of a support disk, see e.g. Fig. 7 ) Mistake. In addition, the leading edge 26 of the airfoil 16h is also equipped with an irregular contour, which also helps to reduce the development of disruptive noise.

Fig. 10 illustrated the shovel blade Fig. 9 in an installed state in an impeller. In the side view of the impeller 10 ″, the blade 16h, which is shown in FIG Fig. 9 is illustrated, shown in the assembled state between the support plate 12 and the cover plate 14 of the impeller 10 ″.

Fig. 11 shows views of a cover plate of an embodiment of a fan according to the invention. Figure 11a shows the cover plate 14 'in a plan view and Figure 11b shows the cover plate 14 'in a perspective view. To illustrate the irregularity of the outer contour of the cover plate 14 'is similar to that in FIG Fig. 7 a regular circumference 22 'is also shown here as a reference.

Fig. 12 FIG. 11 shows a view of an impeller with the cover disk from FIG Fig. 11 . The impeller 10 '"has, like that in Fig. 8 The illustrated impeller 10 ″ has the support disk 12 ′ with an irregular circumference, the impeller 10 ′ ″ also having blade blades with irregular trailing edge contours and at least one blade 16g with an irregular trailing edge and an irregular leading edge (see Fig. 9 ) is provided. The impeller 10 '"also has the cover plate 14', which in FIG Figures 11a and 11b is shown.

Fig. 13 shows another illustration of the impeller shown in Fig. 2 is illustrated. As already discussed above, the impeller 10 comprises the support disk 12, several blades 16a-16g (the blade 16d is shown in FIG Fig. 13 covered by the cover plate 14) and the cover plate 14.
It should be noted that the illustrated contours of the trailing edges, the leading edge, the support disk and the cover disk are only intended to serve as an illustration, without the invention being restricted to the specific shapes.
Fig. 14 shows schematically a flowchart which illustrates an embodiment of a method according to the invention for constructing a fan.
In step 101, two blades are first designed, in which step the trailing edges and, if applicable, the leading edges and / or the surface contours are each designed in such a way that they differ from one another.
In step 103, a further airfoil is first designed, this airfoil in turn being designed in such a way that it differs from all previously designed airfoils with regard to at least the trailing edge contour and / or inclination. This step is repeated until the intended number of blades has been laid out.
In step 105, the positions and orientations of the airfoils are initially determined provisionally, with these positions and / or orientations being iteratively adapted in step 107 until a desired reduction in an imbalance possibly caused by the different configurations of the airfoil is achieved and thus the construction of the fan can be regarded as completed in this regard.

It is to be understood that the method described above represents only one embodiment of the method according to the invention. In particular, it is possible to modify the sequence of the individual design steps and also to change the respective dependencies. For example, it is possible first of all to provide a positioning and orientation of the airfoils in which, assuming certain conditions for the specific design of the respective airfoil, an undesired imbalance is avoided to a sufficient extent, the respective contours of the airfoil then taking into account the above conditions to be determined. An adaptation of the orientation and / or positioning of the blade blades may possibly be unnecessary or supplemented by adapting the outer contours of the support disk and / or the cover disk, this adaptation advantageously being an irregular adaptation, as is shown, for example, in FIGS Fig. 7, 8 , 11 and 12th is illustrated.
Fig. 15 shows schematically a flow diagram which illustrates an embodiment of a method according to the invention for the pressurized delivery of gaseous medium.
In step 111 the fan is put into operation and begins to suck in medium and to release it under the application of pressure.
Here, the rotating element of the fan rotates so that the various blades of the rotating element pass one component of the fan one after the other. These respective passages are illustrated by steps 113, 115 and 117, this sequence of steps being repeated until the fan is switched off (step 119).
Due to the design of the blades, the media impulses that are connected to the component with passages 113, 115 and 117 (here only three passages are arbitrarily addressed, without this being understood as a restriction) on the component are different, so that these media impulses do not interrelate can combine together to form an annoying noise.

Reference list

10, 10 ', 10 ", 10"'

Wheel

12, 12 '

Support disc

14, 14 '

Cover disk

16a-16h

Shovel blade

16a'-16h '

Trailing edge

18th

Center line

20th

Mounting slots

22, 22 '

regular scope

24

Appendix

26th

Leading edge

101

Design of two shovel blades

103

Design of further blades

105

Determination of positions and orientations

107

Adjustment of positions and / or orientations

111

Installation

113, 115, 117

passage

119

Shutdown

Claims (9)

1. A fan with a rotating element (10, 10', 10", 10"') by which a gaseous medium is sucked in and is released again under pressure,

   wherein the rotating element (10, 10', 10", 10'") comprises a plurality of fan blades (16a-16h),

   wherein at least two of the plurality of fan blades (16a-16h) differ from each other in a characteristic that impacts a media impulse exerted by the respective fan blade (16a-16h) on a component of the fan in operation,

   characterized in that

   each fan blade (16a-16h) of the plurality of fan blades (16a-16h) differs from each other fan blade (16a-16h) of the plurality of fan blades (16a-16h) at least in a contour and/or tilt of an outflow edge (16a'-16h') of the fan blades (16a-16h) and

   each fan blade (16a-16h) of the plurality of fan blades (16a-16h) differs from each other fan blade (16a-16h) of the plurality of fan blades (16a-16h) further at least in an offset of an arrangement of the fan blades (16a-16h) with respect to an initial arrangement given by a rotation symmetry of the rotating element (10, 10', 10", 10'"), wherein the rotation symmetry corresponds to a number of fan blades of the rotating element (10, 10', 10", 10'"),

   wherein the differences concerning the outflow edge and of the arrangement are scaled such that a centre of mass of the rotating element (10, 10', 10", 10'") coincides with a rotation axis of the rotating element (10, 10', 10", 10'").
2. The fan according to claim 1,
   wherein further at least two of the plurality of fan blades (16a-16h) differ from each other in a further characteristic having an impact on a media impulse exerted by the respective fan blade (16a-16h) on a component of the fan in operation, wherein the further characteristic that has an impact on a media impulse exerted by the respective fan blade (16a-16h) on a component of the fan in operation further comprises

   - a contour and/or tilt of an inflow edge (26) of the fan blade (16a-16h), and/or

   - a surface contour of the fan blade (16a-16h).
3. The fan according to claim 1,
   wherein the offset of the arrangement comprises an orientation and/or a positioning of the fan blade (16a-16h).
4. The fan according to claim 1,

   wherein the fan blades (16a-16h) differ in terms of a deviation of the contour of their respective outflow edge (16'-16h') with respect to a given initial outflow contour,

   wherein the deviation of the contour of the outflow edge (16a'-16h') of at least one fan blade (16a-16h) varies irregularly from the initial outflow contour along the extension of the outflow edge (16a'-16h'), wherein a maximum deviation in a direction is at least 1/150 of a fan blade length and a maximum deviation in a direction opposed to the direction is at least 1/150 of the fan blade length.
5. The fan according to claim 2,

   wherein the further characteristic that has an impact on a media impulse exerted by the respective fan blade (16a-16h) on a component of the fan in operation comprises a contour of an inflow edge (26) of the fan blade (16a-16h),

   wherein the at least two fan blades (16a-16h) differ in terms of a deviation of the contour of their respective inflow edge (26) with respect to a given initial inflow contour,

   wherein the deviation of the contour of the inflow edge (26) of at least one fan blade (16a-16h) varies irregularly from the initial inflow contour along the extension of the inflow edge (26), wherein a maximum deviation in a direction is at least 1/150 of a fan blade length and a maximum deviation in a direction opposed to the direction is at least 1/150 of the fan blade length.
6. The fan according to claim 4 or 5,
   wherein the maximum deviation in the direction is less than 1/15 of the fan blade length and the maximum deviation in the opposed direction is less than 1/15 of the fan blade length.
7. The fan according of any of the preceding claims,

   wherein the fan is a centrifugal fan or a mixed flow fan and the rotating element (10, 10', 10", 10"') comprises a support disc (12, 12') and/or a cover disc (14, 14'),

   wherein an outer contour of the support disc (12, 12') and/or the cover disc (14, 14') comprises a varying deviation of the perimeter with respect to a circle,

   wherein a maximum deviation to the outside is at least 1/150 of a disc diameter and a maximum deviation to the inside is at least 1/150 of the disc diameter.
8. A method for constructing a fan with a rotating element (10, 10', 10", 10'") by which a gaseous medium is sucked in and realised again under pressure, wherein the rotating element (10, 10', 10", 10'") comprises a plurality of fan blades (16a-16h), wherein the method comprises:

   designing (101, 103, 105, 107) of the fan blades (16a-16h) in such a way that at least two of the plurality of fan blades (16a-16h) differ from each other in a characteristic that impacts a media impulse exerted by the respective fan blade (16a-16h) on a component of the fan in operation,

   characterized in that the designing (101, 103, 104, 107) is provided in such a way that

   each fan blade (16a-16h) of the plurality of fan blades (16a-16h) differs from each other fan blade (16a-16h) of the plurality of fan blades (16a-16h) at least in a contour and/or tilt of an outflow edge (16a'-16h') of the fan blades (16a-16h) and

   each fan blade (16a-16h) of the plurality of fan blades (16a-16h) differs from each other fan blade (16a-16h) of the plurality of fan blades (16a-16h) further at least in an offset of an arrangement of the fan blades (16a-16h) with respect to an initial arrangement given by a rotation symmetry of the rotating element (10, 10', 10", 10"'), wherein the rotation symmetry corresponds to a number of fan blades of the rotating element (10, 10', 10", 10'"),

   wherein the differences concerning the outflow edge and the arrangement are scaled such that a centre of mess of the rotating element (10, 10', 10", 10'") coincides with a rotation axis of a rotating element (10, 10', 10", 10'").
9. A method for release of gaseous medium under pressure comprising:

   sucking in the medium by means of a rotating element (10, 10', 10", 10'") of a fan, wherein the rotating element (10, 10', 10", 10'") comprises a plurality of fan blades (16a-16h),

   wherein a respective fan blade (16a-16h) impacts a media impulse on a component of the fan upon passing the component during the rotation of the rotating element (10, 10', 10", 10'"),

   wherein the method comprises that the respective media impulses of at least two of the plurality of fan blades (16a-16h) differ due to the at least two fan blades (16a-16h) differing from each other in a characteristic that impacts the respective exerted media impulse,

   characterized in that

   each fan blade (16a-16h) of the plurality of fan blades (16a-16h) differs from each other fan blade (16a-16h) of the plurality of fan blades (16a-16h) at least in a contour and/or tilt of an outflow edge (16a-16h) of the fan blades (16a-16h) and

   each fan blade (16a-16h) of the plurality of fan blades (16a-16h) differs from each other fan blade (16a-16h) of the plurality of fan blades (16a-16h) further at least in an offset of an arrangement of the fan blades (16a-16h) with respect to an initial arrangement given by a rotation symmetry of the rotating element (10, 10', 10", 10'"), wherein the rotation symmetry corresponds to a number of fan blades of the rotating element (10, 10', 10", 10'"),

   wherein the differences concerning the outflow edge and the arrangement are scaled such that a centre of mass of the rotating element (10, 10', 10", 10"') coincides with a rotation axis of the rotating element (10, 10', 10", 10'").

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