EP3111094B1 - Flow rectifier and fan assembly having a flow rectifier - Google Patents

Description

The invention relates to a flow straightener for a flow inlet opening of a fan assembly according to the preamble of claim 1 and a fan assembly, preferably a tube fan assembly according to claim 15. Particularly preferably, in the fan assembly is a fan assembly in which the inflow is mainly directed axially, as especially in the case of pipe ventilator arrangements.

From the EP 0 547 253 B1 a flow straightener for a fan is known which comprises a lattice structure formed by lattice webs, the suction-side outer surface is arranged in a radial plane. The lattice structure of the known flow rectifier is according to the embodiment according to Fig. 1 The document of extending radially in the radial direction webs and these crossing, extending in the circumferential direction and concentrically arranged circumferential webs formed. The radial webs run in a star shape toward a central inlet opening, which is bounded by a circumferential web in the radial direction. A disadvantage of the known flow rectifier is a high pressure loss, which leads to a high power consumption of the fan. In addition, the known flow straightener seems to be in need of improvement in terms of minimizing the low-frequency blade turning tones.

An alternative flow straightener is in the DE 1 052 624 described. The known flow rectifier comprises star-shaped baffles which, according to one exemplary embodiment, run onto a guide body of an impeller, wherein the guide body axially passes through an outlet opening of the flow rectifier. The guide body is a separate from the baffles Component, which is supported by the baffles. In another embodiment, the radially and axially extending baffles meet in a central meeting place. According to a further alternative embodiment, the baffles define a central inlet opening.

In the case of the flow rectifiers known from the aforementioned publication, the noise level in the low-frequency range of the blade tones is not sufficiently reduced.

From the EP 2 123 917 A2 is a flow straightener known whose height envelope surface has the shape of a three-dimensional geometric body.

The US 2013/0052000 A1 describes a flow straightener with a cap which is staggered with respect to a residual altitude surface area - it is an element which is placed at the flow outlet. The axial extension of the cylindrical surface of the cap serves to optimize the flow in this region between an innermost, axially stationary annulus and the cap.

The EP 2 196 739 A1 also deals with flow straighteners.

Based on the aforementioned prior art, the present invention seeks to provide a particular for tubular fan assemblies or generally fan assemblies with largely axially directed inflow suitable flow rectifier, which reduces turbulence in the inflow and the low-frequency rotary sound, preferably with minimized pressure drop of the flow rectifier. Furthermore, the object is to provide a fan assembly, in particular a pipe ventilator arrangement with such a flow rectifier.

This object is achieved with regard to the flow rectifier with the features of claim 1 and with respect to the fan assembly having the features of claim 15. Advantageous developments of the invention are specified in the subclaims.

The invention has recognized that in particular with the use of flow rectifiers in connection with fan arrangements with mainly axially directed inflow, in particular tube fan arrangements, a centric inlet opening of the flow rectifier is disadvantageous with regard to an optimized noise reduction of the rotary tones in the low-frequency range. In the Applicant's opinion, this is due to the fact that appreciable non-rectified flow components can flow in the direction of the fan wheel due to the centric inflow opening provided in the prior art. Instead of an inflow opening, a closed flow rectifier penetrated by a longitudinal center axis of the flow rectifier is therefore provided in a flow rectifier designed according to the concept of the invention, which can not be flowed through, so that all sucked air is forced through the grid openings bounded by intersecting grid webs of a grid structure. The formation of the grid openings is a further essential feature of the flow straightener according to the invention - for optimized rectification and thereby optimized Drehtongeräuschminimierung in the low-frequency range, namely, it is advantageous that the grid openings are not limited as partially in the prior art only extending in the radial direction Leitfinnen but that the grid openings are closed on all sides or are limited by intersecting grid bars, the form a lattice structure, in particular in each case of two radial webs extending in the radial direction and optionally additionally in the axial direction and of two webs extending in the circumferential direction. In other words, it is essential that the (lattice) openings are provided in a lattice structure and are not limited exclusively by star-shaped baffles. In other words, the flow straightener constructed according to the concept of the invention has a centric region which is closed relative to the axial projection surface and which is surrounded by a multiplicity of lattice openings, each of which is delimited by a plurality of intersecting lattice rods. Preferably, the grid openings are each limited by four crossing points.

With regard to the concrete design of the closed central section, there are different possibilities. In any case, the central central portion is axially spaced from the outlet opening, more precisely a center of the outlet opening, wherein it is particularly preferred when a longitudinal central axis extends through the central portion and the center of the outlet opening, still more preferably this longitudinal central axis in the assembled state of the flow rectifier with a Rotary axis of an associated fan of a fan assembly axially aligned.

With regard to the specific design of the closed central section, there are, as indicated, different possibilities. In principle, it is conceivable to form this as a cover part which is separate from the grid structure and which closes off a centric opening from at least one axial side and / or covers a grid structure section. It is very particularly preferred if the lattice webs are firmly connected to the closed central section, wherein it is particularly preferred, in particular with regard to a design of the flow rectifier as a plastic injection-molded part, when the grid bars are formed integrally with the closed central portion. In particular, in a latter variant, as will be explained later, the closed central portion can be used as Anspritzfläche or injection.

Overall, the designed according to the concept of the invention flow straightener, as mentioned, for fan systems with mainly axial inflow, such as pipe fan assemblies. Optimized is the flow straightener in particular for small to very small sizes of fan assemblies, especially with fan diameter from a range between 10mm and 220mm, preferably between 10mm and 120mm and / or for fans with a flow rate between 0.5 ³ / h and 50m ³ / H. In an embodiment of at least the lattice structure and the closed central portion as, in particular common injection molded part, the lattice webs can be designed to minimize pressure losses as thin as possible.

As already mentioned, it is particularly preferred if the closed central portion is integrally formed with the grid webs, which is preferably possible by forming the central portion together with the grid structure as a common plastic injection molded part. More preferably, the entire flow rectifier is formed as a plastic injection molded part. Alternatively, it is conceivable for the central section to be formed by a cover part which is separate from the grid webs and which is fixed in a component of the flow rectifier, in particular on the grid structure, for example by screwing, latching or in some other way. Preferably, in this case, the central section either covers a centric entrance opening within the lattice structure or covers a lattice structure section.

There is also a possibility for forming the closed central portion to form this from a meeting point of several, preferably star-shaped converging in the meeting point grid bars, wherein the grid bars are preferably radial webs, which, as will be explained later, in addition also can extend in the axial direction, in particular when the lattice structure, as will also be explained later, the envelope surface of a three-dimensional geometric body is limited. Of course, the central portion of the above embodiment is not punctiform - but the feature is to be understood that the surface of the central portion is only formed by the meeting grid bars in contrast to an alternative embodiment in which the closed central portion has a greater cross-sectional area extension and the grid bars with Distance abut a longitudinal central axis of the flow rectifier on the outer circumference of the central portion, in particular ends.

As already indicated, it is provided according to the invention that the suction-side outer side of the lattice structure delimits the envelope surface of a three-dimensional geometric body (an envelope surface because the "lateral surface" is perforated by the lattice openings in the specific case). In other words, if the grid openings bounded by this or not connected would form the lateral surface of a three-dimensional geometric body together with the then filled areas, this three-dimensional body is particularly preferably curved convexly in the direction of the suction side or concave in the opposite direction is arched. Preferably, the radius of curvature of the convex or concave arched grid structure is selected from a value range between 5 mm and 120 mm, preferably between 5 mm and 60 mm. In principle, it is preferable if the radius of curvature is at least approximately corresponds to half the diameter of the flow straightener. It is particularly expedient if the aforementioned three-dimensional body whose envelope surface or envelope contour is delimited by the grid structure is a spherical segment stump, ie the lateral surface preferably has the contour of a no longer complete spherical cap from which an end-side spherical cap section has been removed it is at a Kugelabschnittsstumpf to a spherical disk with parallel end or base surfaces. Alternatively, it is conceivable that the aforementioned three-dimensional geometric body is formed as a truncated cone or as a truncated pyramid, wherein the truncated pyramid is n-side and n≥3, in particular 4, 6, 8 or 12. Most preferably, a base of the three-dimensional body is circular.

The envelope surface according to the invention has a discontinuous course. In this case, the Hüllmantelfläche on two radially adjacent ring portions, which are connected to each other via a discontinuous connection portion. Preferably, in the connecting section grid webs project outwards.

The lattice structure ensures a homogenization of the inflow by reducing turbulence. Due to the walls formed by the bars, velocity fluctuations perpendicular to the main flow direction are hindered. On the distance between the walls to each other this influence can be controlled, wherein it is important at the same time and is advantageous that the pressure loss caused by the grid structure according to the invention is minimized.

Also with regard to the geometry of the closed central portion, there are different forms of implementation. In the simplest case, the central portion is flat disc-shaped or is the central portion as Flat section formed, in particular with a suction-side outer surface, which is arranged in a radial plane so even. Alternatively, the suction-side surface of the closed central portion is formed as a lateral surface of a three-dimensional geometric body, which is preferably curved in the direction of the suction side convex or in the opposite axial direction, that is formed concave. It is possible to form the suction-side surface as a lateral surface of a spherical segment, a spherical segment stump, a cone, a truncated cone, a pyramid or a truncated pyramid, wherein the pyramid is in turn formed on the n-side, where n≥3, preferably 4, 6, 8 or 12 ,

Due to the three-dimensional shaping in combination with the grid structure, an optimized noise reduction of the rotary sound can be achieved with minimized pressure loss.

It has proved to be particularly advantageous if the axial projection area of the central portion is not greater than the axial projection area of a hub portion or of a hub of the fan wheel. In other words, it is advantageous if the closed central section is preferably smaller or at most congruent with the projection surface of the hub of the fan wheel.

It has proven to be particularly expedient if an axial height H of the flow rectifier, which is preferably measured starting from the suction side of the central section, is selected as a function of the diameter of the outlet opening, the ratio preferably being 0.5 ≦ H / D _A ≤0,5. In this case, the diameter D _{A of} the outlet opening preferably corresponds at least approximately to the diameter of a fan wheel in a fan arrangement comprising the appropriately designed flow rectifier.

The above embodiment is advantageous in the case of the realization form of the flow rectifier according to the invention, in which the suction-side outer surface of the lattice structure delimits the envelope wall structure of the three-dimensional geometric body.

As particularly advantageous in terms of noise reduction in the low-frequency range has been found, if the lattice structure forming the grid structure of extending radially and in a three-dimensional configuration of the suction-side outer surface of the grid structure in the axial direction extending radial webs and of itself in the circumferential direction around the central portion extending, the radial webs preferably at an angle of 90 ° ± 10 ° deviation intersecting circumferential webs is formed or when the grid webs include such radial webs and peripheral webs. It is particularly preferred if the aforementioned radial webs meet radially outward on a circumferential, preferably circular edge web or pipe section, wherein even more preferably the edge web or pipe section simultaneously forms an outlet opening edge which limits the outlet opening. Ideally, the aforementioned edge web is contoured circular.

It is particularly expedient if the circumferential webs are arranged concentrically, wherein in a first embodiment of the radial distance of each adjacent peripheral webs for all peripheral web pairings is the same. Alternatively, the radial distance of circumferential webs may vary.

Ideally, the depth extent of the circumferential webs is not exactly aligned axially, but the peripheral webs are inclined relative to an axial, in particular conically contoured, very particularly preferably such that the circumferential webs the air sucked in the direction of a longitudinal central axis redirect. It is very particularly preferred if a plurality of circumferential webs in the form of nested, axially tapered funnels are formed or arranged.

Also with regard to the design and orientation of the radial webs, there are different possibilities. So it is conceivable that the radial webs as a radially continuous, i. extending from the closed central portion continuously in the radial and preferably at the same time also axial direction, and then to open radially outward preferably in the aforementioned edge web or pipe section. Alternatively, it is conceivable for radial webs spaced apart from one another from the circumferential webs to be offset relative to one another in the circumferential direction, in particular to thereby form or limit grid openings having at least approximately the same cross-sectional area with different radial positions.

Thus, it is within the scope of an advantageous development of the invention that the, preferably approximately trapezoidal, cross-sectional areas of most grid openings, preferably all grid openings are the same size, which by varying the radial distances of peripheral webs and / or by varying the pitch of the radial webs depending on their Radial position can be realized.

In this case, the number of circumferentially annularly juxtaposed openings varies depending on the radial position, so that in a first, radially inwardly located ring of circumferentially juxtaposed grid openings fewer Gitteröffnunggen are provided as in a radially further outward, preferably spaced by a circumferential ridge Ring of grid openings, wherein it is particularly preferred if the measured in the circumferential direction average grid width in different rings of grid openings is equal to. To achieve the same or unequal opening cross-sections, the spacing of the circumferential webs can additionally or alternatively be varied. The radial distance of the circumferential webs can be the same size from peripheral web to peripheral web or different sizes.

An embodiment in which the grid openings in a first ring in front of the circumferential directions have a pitch which is different from the pitch of the grid opening of a radially adjacent ring from the circumferential directions of juxtaposed grid openings, in particular, but not necessarily, is particularly preferred. to obtain grid openings with the same cross-sectional area. In other words, it is particularly preferred if the radial webs which are radially spaced apart from each other over a circumferential web are offset in the circumferential direction with respect to one another. Although such a flow straightener can be produced only comparatively complicated, in particular in plastic injection molding, but the Drehtoundäuschsminimierungseffekte are particularly optimal.

It has proven to be particularly advantageous if the depth of cut of at least two webs delimiting a grid opening is different. This embodiment is particularly interesting when two radially adjacent surface portions are provided by annularly arranged grid openings, wherein the lateral surface in this case preferably makes a discontinuous jump in the radial direction, which is preferably caused or realized by radially projecting, radially and axially extending Webs whose depth of burial is thus comparatively large. It is also conceivable that the depth of cut of a web varies over its circumferential or alternatively radial extent.

It is very particularly preferred for optimum noise reduction in the low-frequency range if the ratio of a web depth substantially extending in the axial direction or a web thickness extending perpendicular to the web longitudinal extent and the web depth extension is greater than 5.
For an optimized noise reduction, it is advantageous if for a ratio of a mean radial width W _R (mean distance between adjacent circumferential webs) and an average circumferential width W _U (mean distance between adjacent radial webs): 1/3 <W _U through W _R < third

It is particularly expedient for optimized noise minimization if the following applies for a respective ratio of a diagonal width of the grid openings and a diameter of the outlet opening: 0.01 <W _D / D _A <0.15.

The diagonal width of grid openings juxtaposed in the radial direction and / or of the grid openings arranged adjacent to one another in the circumferential direction may vary or, alternatively, be the same. In the context of the present application, a mean width is generally understood as the arithmetic mean of all corresponding (radial or circumferential) widths of the respective opening.

The invention also leads to a fan arrangement, preferably a tube ventilator arrangement, with a fan, to which a flow inlet opening, in particular a flow channel, for sucking air is assigned, on the suction side in front of which, preferably detachably, a flow rectifier designed according to the concept of the invention is arranged. The flow rectifier can be set outside in the region of a peripheral edge of the flow inlet opening and / or at least partially inserted into the flow inlet opening, wherein a fastening can also take place within the flow channel, for example by latching. A longitudinal central axis of the flow rectifier, which preferably runs centrally through the closed central section, preferably aligns in the axial direction with the axis of rotation of the fan.

Particularly preferably, the flow rectifier designed according to the concept of the invention is designed for fan arrangements which promote a volume flow of between 0.5 and 50 m ³ / h.

It is particularly expedient if, as mentioned, the fan arrangement is designed such that the inflow is directed at least for the most part axially, as is the case, for example, with tube fan arrangements in which the fan is arranged within a tube which forms the flow channel whose inlet opening the flow straightener is assigned.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings.

Fig. 1:

lediglich zu Erläuterungszwecken eine perspektivische Ansicht einer nicht erfindungsgemäßen Lüfteranordnung mit einem nach dem Konzept der Erfindung ausgebildeten Strömungsgleichrichter, zum Teil geschnitten,

Fig. 2:

eine Detailansicht aus Fig. 1,

Fig. 3:

lediglich zu Erläuterungszwecken eine als Rohrlüfteranordnung ausgebildete nicht erfindungsgemäße Lüfteranordnung mit einem nach dem Konzept der Erfindung ausgebildeten Strömungsgleichrichter,

Fig. 4:

lediglich zu Erläuterungszwecken eine nicht erfindungsgemäße Variante eines Strömungsgleichrichters mit sternförmig verlaufenden Radialstegen sowie Umfangsstegen, wobei die Radialstege auf einen einteilig mit diesen ausgebildeten geschlossenen Zentralabschnitt zulaufen,

Fig. 5:

lediglich zu Erläuterungszwecken eine alternative nicht erfindungsgemäße Variante mit im Vergleich zu Fig. 4 großflächigerem geschlossenen Zentralabschnitt, wobei bei dem Ausführungsbeispiel die mittleren Gitterweiten von nach unterschiedlichen Radialpositionen befindlichen Gitteröffnungen zumindest näherungsweise gleich sind,

Fig. 6:

lediglich zu Erläuterungszwecken eine alternative nicht erfindungsgemäße Variante eines Strömungsgleichrichters mit in radialer Richtung gleichbleibender Teilung der Radialstege,

Fig. 7:

eine erfindungsgemäße Ausführungsvariante eines Strömungsgleichrichters mit einer unstetigen Hüllmantelfläche der Gitterstruktur,

Fig. 8:

lediglich zu Erläuterungszwecken eine nicht erfindungsgemäße weitere alternative Variante eines Strömungsgleichrichters, bei welcher der geschlossene Zentralabschnitt von dem Treffpunkt der Radialstege gebildet ist, und

Fig. 9a und Fig.

9b: lediglich zu Erläuterungszwecken eine nicht erfindungsgemäße Variante eines Strömungsgleichrichters mit im Vergleich zu den vorstehend beschriebenen Strömungsgleichrichtern nur geringfügig konvex gewölbten Gitterstrukturen.

In den Figuren sind gleiche Elemente und Elemente mit der gleichen Funktion mit den gleichen Bezugszeichen gekennzeichnet.These show in:

Fig. 1:

for illustrative purposes only, a perspective view of a fan assembly not according to the invention with a flow rectifier designed according to the concept of the invention, partly cut away,

Fig. 2:

a detailed view Fig. 1 .

3:

for illustrative purposes only, a fan assembly not according to the invention designed as a tube fan arrangement with a according to the concept of the invention formed flow straightener,

4:

for illustrative purposes only, a non-inventive variant of a flow straightener with star-shaped radial webs and circumferential webs, wherein the radial webs run on an integrally formed with these closed central portion,

Fig. 5:

merely for explanatory purposes, an alternative variant not according to the invention with compared to Fig. 4 larger-scale closed central portion, wherein in the embodiment, the average grid widths of located after different radial positions grid openings are at least approximately equal,

Fig. 6:

merely for explanatory purposes an alternative variant of a flow rectifier according to the invention with a radial pitch of the radial webs,

Fig. 7:

an embodiment variant according to the invention of a flow rectifier with a discontinuous outer surface of the lattice structure,

Fig. 8:

merely for explanatory purposes, a non-inventive further alternative variant of a flow straightener, in which the closed central portion is formed by the meeting point of the radial webs, and

Fig. 9a and Fig.

9b: merely for explanatory purposes, a non-inventive variant of a flow rectifier with only slightly convex curved grating structures in comparison to the flow rectifiers described above.

In the figures, like elements and elements having the same function are denoted by the same reference numerals.

In Fig. 1 a fan assembly 1 is shown, which comprises a designed as an axial fan (here an external rotor rotor) 2, which has a plurality of circumferentially juxtaposed paddle wheels 3, which are arranged on a hub 4. The fan 2, more precisely the paddle wheels 3, rotate about an axis of rotation 5. The fan 2 is arranged within an axial flow channel 6 which delimits a flow inlet opening 7 at its upper end in the plane of the drawing.
The flow inlet opening 7 of the flow channel 6 is associated with a flow rectifier 8, which is fixed in the example shown in front of the flow inlet opening 7 on a mounting plate 9. The flow rectifier 8 is arranged so that its axial longitudinal central axis is aligned axially with the axis of rotation 5.
The flow rectifier 8 is characterized by a closed central portion 10, here for example made of plastic, which is formed in the concrete embodiment as a one-piece injection molded part with the closed central portion 10 radially outwardly enclosing grid structure 11. The grid structure 11 is formed in the concrete example of a Variety of intersecting webs, namely from radially outward to radially inwardly extending radial webs 12 and of these approximately at 90 ° angle (± 10 °) crossing, concentric with the axis of rotation 5, arranged annular peripheral webs thirteenth
How out Fig. 1 can be seen, the suction-side outer surface of the lattice structure bounds a (shell) lateral surface of a geometric body, in the concrete example of a Kugelabschnittstumpfes, ie a spherical disk.
The radial webs 12 therefore extend not only in the radial but also in the axial direction, here in the direction of the suction direction, so that the convexly curved three-dimensional body is obtained.
The radial webs 12 extend from an annular edge web 14, with which the flow rectifier 8 rests on the mounting plate 9 radially inward to the non-permeable, closed central portion 10th
An axial height H of the flow rectifier 8, measured along the axis of rotation 5 is measured from a center of the suction-side outer surface of the closed central portion 10 to a center of an outlet opening 15 of the flow rectifier 8, which is bounded by an annular outlet opening edge 16, which in turn in the concrete Example of the edge web 14 is formed. The outlet opening 15 has a diameter D _A , which corresponds substantially to the diameter of the flow channel. The blade wheels 3 in a radial direction shortly before the inner circumference of the flow channel 6, so that in approximation, the outer diameter of the fan wheel 1 corresponds to the diameter D _A. In the specific example of the axial height H, the condition applies: $$0.05\le \mathrm{H}/{\mathrm{D}}_{\mathrm{A}}\le \mathrm{0.5.}$$

In the example shown, a closed central portion 10 is formed as a flat plate, the suction-side outer surface is substantially in a radial plane, that is arranged parallel to the outlet opening 15.
In Fig. 2 a section of the grid structure 11 is shown in an enlarged view. The grid openings 17 are concretely delimited by the radially extending in the radial direction and in the specific example in the axial direction radial webs and the concentrically arranged circumferential webs 13, wherein Circumferential webs and radial webs at an angle α of about 90 ° ± 10 ° deviation meet.

The lattice webs have a groove depth T _s extending substantially in the axial direction and a web thickness D _s . The grid openings 17 have a diagonal manner W _D , a mean radial width W _R (relative to a grid opening mean distance between two circumferentially spaced circumferential webs) and a mean circumferential width W _U (relative to a grid opening mean distance between two in the circumferential direction juxtaposed radial webs). For the grid structure shown, the relation 1/3 <W _U / W _R <3 applies. Further, the relationship 0.01 <W _D / D _A <0.15 applies.

As it turned out Fig. 1 results in the concrete example of the flow rectifier 8 is realized both an equal pitch of the radial webs in the circumferential direction and an unequal division of the circumferential webs in the radial direction. This results in each case over a circumferential ridge spaced annular rows of grid openings, wherein the grid openings of adjacent rings are different from each other Have cross-sectional area, since the radial webs are arranged in a star shape and thus increases their circumferential width W _U from radially inward to radially outward. The mean circumferential width of grid openings arranged in a respective ring is constant in the example shown.

In Fig. 3 is a fan assembly designed as a fan assembly 1, shown with a tubular flow channel 6, in which a fan 2 is arranged. The flow channel 6 defines a flow inlet opening 7, which is associated with a flow rectifier 8. This flow rectifier 8 also has a closed central section 10, which is surrounded by a lattice structure 11 which delimits a lateral surface of a dome stump.
In Fig. 4 is the flow straightener 8 off Fig. 3 shown in an enlarged view. To recognize is the closed, as in the example according to Fig. 1 axially spaced from the outlet opening 15 central portion 10, run radially star-shaped on the radial webs 12. In the concrete example, the flow straightener 8 comprises two types of radial webs, namely the radial webs arranged in an inner ring which delimit comparatively large grid openings, and radial radially outwardly extending radially and axially extending radial webs which are crossed by concentrically arranged circumferential webs 13. It can be seen that the circumferential webs 13 are conically inclined radially inward and thus guide the air flow in the direction of the axis of rotation.

The example of a flow rectifier 8 according to Fig. 5 differs from the preceding examples in that the average circumferential grid width U is at least approximately equal for all grid openings 11. This will be done ensures that the radial webs do not run continuously in the radial direction, but that in the radial direction side by side arranged radial webs are arranged offset in the circumferential direction to each other, so that the resulting ring rows of grid openings have a different number of grating openings. The central portion 10 also serves as an injection point 18 for the one-piece production of the flow rectifier as a plastic injection molded part.

The example of a flow rectifier 8 according to Fig. 6 differs from the embodiment of FIG. 10 in that here the number of grid openings in the grid opening rings is the same, since the radial webs 12 to extend radially continuous star-shaped on the closed central region 10. As a result, the circumferential grid widths W _U of grid openings which are adjacent in the radial direction vary.

In the embodiment according to the invention Fig. 7 the Radialstegtiefenerstreckung varies. In particular, it can be seen that two of the lattice structure 11, which are juxtaposed in the radial direction and are continuously connected to one another, are limited by geometrical bodies. The discontinuity is due to the fact that the radial webs are increased in the transition region in the radial direction or protrude radially, ie form an overhang.

In the example of a flow straightener according to Fig. 8 is the closed central portion 10 formed by a meeting point 19 of the radial webs 12, which in the concrete example, only by way of example to the edge web 14th

In the example according to the Fig. 9a and 9b is the lattice structure 11 only slightly convex, but, as can be seen, a realized three-dimensional geometric shape. The flow rectifier 8 is a tube of a tubular fan assembly attachable with an end-side cylindrical portion 20 which simultaneously axially spaced from the grid structure 11 forms the outlet opening edge 16 which defines the outlet opening 15, from which the closed central portion 10 is axially spaced.

All the examples described above and the embodiment according to the invention can likewise be provided with a cylinder section 20, in particular in order then to insert it into a flow channel, in order then to possibly supply it there, as in the example according to FIGS Fig. 9a and 9b releasably to fix via locking means 21.

Alternatively, the flow rectifier shown can be used to completely accommodate a fan, in particular to protect this filigree training from damage.

LIST OF REFERENCE NUMBERS

1

fan arrangement

2

Fan

3

paddle wheels

4

hub

5

axis of rotation

6

flow channel

7

Flow inlet opening

8th

Flow straightener

9

mounting plate

10

closed central section

11

lattice structure

12

radial webs

13

circumferential lands

14

edge web

15

outlet opening

16

Outlet opening edge

17

grid opening

18

injection point

19

meeting point

20

cylinder section

21

latching means

T _S

web depth

D _S

web thickness

W _D

diagonal width

W _R

radial width

W _U

extensive space

α

angle

Claims (15)

1. Flow rectifier for a flow inlet opening (7) in a fan assembly (1), comprising a lattice structure (11) made of intersecting lattice webs which delimit a plurality of lattice openings (17) for the intake of air, a preferably circular outlet opening (15) being provided for the outflow of air from the flow rectifier (8), which outlet opening is delimited by an outlet opening edge (16), the lattice openings (17) delimited by the lattice structure (11) being arranged in the circumferential direction around or radially outside of a closed central portion (10) which is axially spaced from the outlet opening (15), and the intake-side outer face of the lattice structure (11) delimiting an enveloping lateral surface of a three-dimensional geometric body, in particular of a body which is convexly curved towards the intake side or concavely curved inwards, of a truncated spherical segment, of a truncated spherical segment, of a truncated cone or of a truncated pyramid,
   characterised in that
   the enveloping lateral surface has at least two radially adjacent ring portions, which transition into one another in a mathematically discontinuous manner.
2. Flow rectifier according to claim 1,
   characterised in that
   the closed central portion (10) is integral with the lattice webs of the lattice structure (11), or in that the central portion is formed by a covering part which is separate from the lattice webs of the lattice structure and covers a central opening or a central portion of the lattice structure.
3. Flow rectifier according to either claim 1 or claim 2,
   characterised in that
   the closed central portion (10) is formed by a meeting point of a plurality of lattice webs which preferably converge in the meeting point in a star shape, or in that the lattice webs abut against, in particular end at, the outer circumference of the closed central portion at a radial distance from the radial mid-point of said closed central portion.
4. Flow rectifier according to any of the preceding claims,
   characterised in that
   an intake-side surface of the closed central portion (10) delimits a radial plane, or the intake-side surface of the closed central portion (10) forms a lateral surface of a three-dimensional geometric body, preferably of a body which is convexly curved towards the intake side, of a body which is concavely curved inwards, of a spherical segment, of a truncated spherical segment, of a cone, of a truncated cone, of a pyramid or of a truncated pyramid.
5. Flow rectifier according to any of the preceding claims,
   characterised in that
   an axial height H of the flow rectifier (8), which height is preferably measured starting from the intake side of the closed central portion (10), is calculated from the ratio 0.05≤H/D_A≤0.5, D_A being the diameter of the outlet opening (15) of the flow rectifier (8), which outlet opening is axially spaced from the closed central portion.
6. Flow rectifier according to any of the preceding claims,
   characterised in that
   the lattice webs which form the lattice structure (11) comprise or are formed by radial webs (12), which extend in a radial direction and preferably simultaneously extend in an axial direction, and circumferential webs (13), which extend in a circumferential direction about the closed central portion (10) and preferably intersect the radial webs (12) at an angle (α) of 90° ±10° deviation.
7. Flow rectifier according to claim 6,
   characterised in that
   the radial webs (12) extend radially outwards to meet a circumferential, preferably annular, edge web (14) or tube portion.
8. Flow rectifier according to either claim 6 or claim 7,
   characterised in that
   the circumferential webs (13) are conically contoured and preferably oriented in parallel in relation to their extension in depth.
9. Flow rectifier according to any of claims 6 to 8,
   characterised in that
   the depths (T_S) of the lattice webs which delimit a lattice opening (17) are different and/or in that the radial webs (12) have a depth (T_S) which differs from that of the circumferential webs (13), the depth of the radial webs (12) preferably being greater than the depth of the circumferential webs (13).
10. Flow rectifier according to any of the preceding claims,
    characterised in that
    the lattice webs of the lattice structure (11) have a web depth (T_S) and a web thickness (D_S), where T_S/D_S>5.
11. Flow rectifier according to any of the preceding claims,
    characterised in that
    the lattice openings (17) have an average radial width (W_R) and an average circumferential lattice width (W_U), where 1/3<W_U/W_R<3.
12. Flow rectifier according to any of the preceding claims,
    characterised in that
    the lattice openings (17) have a diagonal width (W_D), where 0.01<W_D/D_A<0.15 and (D_A) is the diameter of the outlet opening (15).
13. Flow rectifier according to claim 12,
    characterised in that
    the diagonal width (W_D) of lattice openings (17) that are adjacent in the radial direction and/or lattice openings (17) that are adjacent in the circumferential direction varies or is the same.
14. Flow rectifier according to any of the preceding claims,
    characterised in that
    the lattice structure (11) and the closed central portion are designed as a common plastics injection-moulded part, preferably having an injection point (18) provided on the central portion.
15. Fan assembly, preferably a tube fan assembly, comprising a fan (2) with which a flow inlet opening for the intake of air is associated, to which flow inlet opening a flow rectifier (8) according to any of the preceding claims is associated, which flow rectifier is preferably arranged, in particular in a detachable manner, in front of the flow inlet opening.

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