EP3198151A2 - Segmented fan wheel - Google Patents

Abstract

The invention relates to a fan wheel having blades (11) which are distributed over the circumference and are connected to one another in the circumferential direction via at least one ring. The fan wheel consists of at least three integrally formed segments (I to VII). Said segments comprise at least one respective ring portion (1) of at least one ring as well as either a blade (11) or at least a portion of the blades. The segments (I to VII) are joined together to form the fan wheel. The ring portions (1) lie against each other with edges (4, 5) which form the joining areas (15, 16) that are disposed transversely with respect to the circumferential direction of the fan wheel. At least one edge (4) of the ring portion (1) of each segment (I to VII) is provided with at least one projecting form-fitting part (18), and at least one edge (4, 5) of the ring portion (1) of each segment (I to VII) is provided with at least one recess (17) which is at least approximately complementary to the form-fitting part (18).

Description

 FAN

The invention relates to a fan according to the preamble of claim 1.

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

Fan wheels are made of different materials. For example, they can be made from fiber-reinforced plastics in one piece. Up to a certain Au ßendurchmesser such Ventiladfertigu has proven ng. For larger sizes, however, the investment in injection molds required increases, as well as the price of parts due to high machine sets for large injection molding machines, so much so that implementation is no longer profitable. In addition, the cylinders of the injection molding machines are generally unable to heat more than 1.5 kilograms of molten fiber-reinforced plastic to sufficiently high temperatures.

For this reason, it is also known to manufacture such fan wheels of several parts. Thus, it is known (DE 41 39 293 A), box-shaped or U-shaped segments fabric and form-fitting to each other and applied to the top and bottom of these assembled elements a hub ring and a cover ring by gluing or welding. The production of such impellers is due to the large number of items consuming, time-consuming and correspondingly expensive, because initially the segments juxtaposed and must be mounted in further steps of the cover and the hub ring.

Fan wheels are also known in which the blades are detachably connected to a hub with which the fan wheel is seated on a drive shaft (DE 1 0 2009 008 508 A1). There are also fan wheels known (WO 20012 / 131617A1), in which the wings are in the form of hollow segments. They are placed against each other and then held together by means of a disc and a cap, which are mounted on the top and on the bottom of the composite wing segments. Such fan wheels can be finished and assembled only consuming. So first the wing segments must be joined together and positioned. Only then the disc and the cap are placed on the two sides of the composite wing segments and attached to them.

There are further fan wheels known (US 2003/0235502A), which are composed of block-shaped segments. The block-shaped inner and outer parts, which form cylindrical outer and inner rings lie with their axially extending surfaces together. Such fan wheels have a high weight and are only suitable for special applications.

The invention has the object of providing the generic fan so that it can be inexpensively and easily manufactured. The fan should only have low weight and high loads, especially high speeds can withstand.

This object is achieved in the generic fan according to the invention with the characterizing features of claim 1.

When fan impeller according to the invention, the joining areas are increased in area by the protruding mold part and the associated recess recess, whereby the fan wheel composed of the segments receives high stability and strength. A joining surface enlarging design differs from a conventional design in that the cross section through the joining areas is not approximately the shape of the two walls of the ring on a short way connecting, to the walls in approximately vertical, straight connection has. If the segments are connected to one another by means of adhesives, then the adhesive surface is enlarged by the design enlarging the joining surface, which leads to an increase in the strength of the fan wheel. This also applies if adjacent segments are welded flat to one another at the joint areas. In addition, an additional form-fitting connection between adjacent segments is formed by these surfaces enlarging the joining surfaces, whereby displacements of the segments relative to one another in the circumferential direction are prevented. In addition, by such a design, the joining of the segments in the manufacturing process can be facilitated because the guide elements form an additional guide adjacent segment relative to each other. The form-fitting parts and the depressions form a spring-groove connection, which leads to a secure connection of the segments. Adjacent segments are assembled axially or radially during the manufacturing process or in a mixed form of axial and radial, so that the protruding form-fitting part passes into the recess of the respectively adjacent ring section section of the adjacent segment. With the formation of the invention, the joining surface is considerably increased, without the wall thickness of the ring sections is increased. As a result of the inventive design of the manufacturing process of the fan wheels according to the invention can be made very economical, fast and accurate.

When fan impeller according to the invention integrally formed segments are used, which have ring sections and fan blades or fan blade sections. The ring sections extend substantially transversely to the fan blades or fan blade sections and extend with a directional component in the circumferential direction of the fan wheel. The edges of the ring sections lying transversely to the circumferential direction of the fan wheel form the joining areas when the fan wheel is assembled. The adjoining segments are connected to each other at the joint areas such that, despite the low Wall thickness of the ring sections a sufficiently strong connection between the segments is possible. In the assembled state, the ring sections of the segments together form one or more rings. Rings may be, in particular, hub rings or cover rings, which connect the wings at their lateral ends with one another in the circumferential direction, or intermediate rings, which are connected to the wings in their intermediate regions between their lateral ends. The hub ring is advantageously used to connect the fan to a drive motor. In stators advantageously the cover ring is used to attach the stator to another device.

Advantageously, the form-fitting part tapers in the direction of its free end. This greatly simplifies the joining of adjacent segments.

In an advantageous embodiment, the depression is arranged in the region between the upper side and the lower side of the annular section. Advantageously, the recess and accordingly also the form-fitting part can be provided approximately in half the thickness of the ring section.

In another advantageous embodiment, the recess to the top or bottom of the ring portion is open. Such a design allows a simple and easy joining process in the production of the fan wheel. Since the recess to one side of the edge portion is open, adjacent segments can be very easily set in the axial direction of the fan wheel during manufacture together.

In such a case, the edge of the ring sections having the form-fitting part and the recess is advantageously stepped. Such elements can be manufactured very easily. It is advantageous if the recess has a depth which is about 0.7 to 2.5 times the wall thickness of the ring portion.

The form-fitting part abuts in a preferred embodiment with at least one of its side surfaces on the side wall of the recess. It is advantageous if the form-fitting part rests with both side surfaces on the side walls of the recess. Then adjacent segments are securely connected securely.

In principle, however, it is also possible that there is a free space between the side surfaces and / or the front side of the form-fitting part and the side walls and / or the bottom of the recess.

The distance of the form-fitting part from the side walls and / or from the bottom of the recess leads to the free space into which, for example, a viscous adhesive can be introduced. This adhesive may be introduced into the recess prior to assembly of the segments.

Advantageously, the transition of at least one side surface of the form-fitting part in the edge of the ring portion is curved, preferably with a radius which is about 0.05 to 0.3 times the wall thickness of the ring portion. The transition is advantageously bionic, i. without constant radius. The bionic design has the advantage that the transition with regard to the flow of force from the form-fitting part into the ring portion of the respective segment can be designed so that cracking is reliably avoided. In this way, the transition can be optimally adapted to the loads occurring during use of the fan wheel.

In an advantageous embodiment, the areas of the annular portion between the side walls of the recess and the top and bottom of the ring portion are about the same thickness. The ring portion may also be designed so that these areas between the side walls of the recess and the top and bottom of the ring portion are different thickness. In this case, the area that contributes little or no power transmission in the use of the fan wheel, be thinner than the opposite area.

In order to achieve a secure connection of adjacent segments without impairing the strength of the fan wheel composed of the segments, it is advantageous if one side surface of the form-fitting part is larger than the opposite other side surface.

In order to further increase the force transferring the segments when joining the segments to the fan wheel, the wall thickness of the ring section in the region of the recess is advantageously greater than the wall thickness in the region outside the recess.

The segments are at least approximately the same. Preferably, all segments have the same shape, so that only a single injection molding tool is required for their production, which keeps the manufacturing costs low.

The cover, hub and intermediate ring sections of adjacent segments are preferably formed such that their edges lying transversely to the circumferential direction are substantially congruent to one another and in each case form joining regions in pairs, with which adjacent segments lie flat against each other. This ensures a simple yet secure connection of the adjacent segments.

These joining areas can lie in a plane spanned by the fan wheel axis and a radial. Depending on the application and requirement profile, the joining areas of adjacent segments can also be formed so that they include an angle with the respective plane spanned by the fan wheel and the radial plane. The angle can be between 0 ° and about 80 °.

Adjacent segments can be connected to one another by gluing and / or welding at the joining regions.

A particularly advantageous embodiment of the fan wheel is that the inflow and outflow ends of the wings have a distance from the joining areas of the fan wheel. In this case serve as connecting surfaces exclusively transverse to the circumferential direction of the fan wheel edges of the ring sections.

But it is also possible that additional joining areas between adjacent segments pass through the wings. In this case, the complete wings are formed only by the joining of the segments. In this case, the butt joints of the wing sections also form joining areas, which are provided in addition to the edges of the ring sections. In this way, the firm connection between the segments can be improved.

The segments are advantageous injection molded parts that can be easily and inexpensively manufactured.

Thermoplastics are advantageously used as the material for the segments.

To increase the strength of the segments and thus of the fan wheel, the thermoplastics advantageously contain reinforcing parts, preferably reinforcing fibers.

The reinforcing fibers advantageously have lengths of about 10μ to over 15 mm, preferably lengths of about 200μ to about 10mm. Such reinforcing fibers can be easily incorporated into the plastic and ensure high strength. Suitable adhesives for bonding the segments to one another are, for example, 1- or 2K adhesives or solvent systems.

Another advantageous connection possibility is to connect the segments by means of laser welding, induction welding or hot gas welding.

In particular, with large diameters of the fan wheel, an advantageous embodiment is to wrap the fan on at least one ring with at least one reinforcing tape. It also holds the segments firmly together, so that the fan can be used even at higher speeds or other high loads.

The reinforcing band may consist of thermoplastic or thermosetting plastic and advantageously contain reinforcing parts, preferably reinforcing fibers.

As reinforcing fibers are advantageously glass, carbon, Ara- mid, thermoplastic or natural fibers into consideration.

The reinforcing band can be easily attached to the circumference of one or more rings of the fan wheel, in particular by welding or gluing.

A further advantageous embodiment is to fasten the reinforcing strip on the circumference of one or more rings of the fan wheel by winding with a thermosetting thermoset.

A particularly optimal training results when the reinforcing tape is wound under pretension on the fan. The fan wheel thus obtained is characterized by a high strength. One Such fan can be used at high speed limits.

In an advantageous embodiment, the bias of the reinforcing tape is in the range between about 10N and about 10kN, preferably between about 10 to 100N per mm ² tape cross-sectional area.

A reliable attachment of the reinforcing strip on the fan is ensured if the fan to accommodate the reinforcing strip is provided on the reinforcing band to be provided with rings with a circumferential groove. I n her can be the amplification band so unterzubeln that it can not slip off the fan.

The use of a reinforcing tape can also be advantageously used when the fan in one piece, d. H . not made of segments, is formed.

The impeller according to the invention may be a radial, an axial or a diagonal fan and a Vorleitrad or Nachleitrad (stator).

The subject of the application results not only from the subject matter of the individual claims, but also by all the information and features disclosed in the drawings and the description. They are, even if they are not the subject of the claims, claimed as essential to the invention, as far as they are new individually or in combination over the prior art.

Further features of the invention will become apparent from the other claims, the description and the drawings.

The invention will be explained in more detail with reference to some embodiments shown in the drawings. Show it

Fig. 1 in axial plan view of an inventive fan wheel, the is formed of several segments.

2 shows an enlarged view of a segment for the production of

 Fan wheel according to FIG. 1.

3 shows an axial plan view of a second embodiment of a fan impeller according to the invention, which is composed of several segments.

4 is a bottom view of another embodiment of a fan impeller according to the invention, which is composed of several segments.

5 shows an enlarged view of a segment for the production of

 Fan wheel according to Fig.4.

Figure 6

and

 7 each further embodiments of segments for producing a fan wheel according to the invention.

Figure 8

to

 11 each in an enlarged view of different versions of cross sections through joining areas of inventive fan wheels, which are designed in a manner enlarging the joining surfaces.

12 is a perspective view of another embodiment of a segment for producing a fan wheel according to the invention.

13 shows in axial section one half of a further embodiment of a fan wheel according to the invention. 14 shows an enlarged view of an embodiment according to the invention of cross sections through joining regions between adjacent segments.

15 shows a schematic representation of the joining of the segments to a fan according to the invention.

16 is a perspective view of another embodiment of an inventive fan wheel, which is assembled from 7 segments of FIG. 17 and is an axial fan with rotating cover ring and an intermediate ring.

17 is a perspective view of a segment of a fan wheel according to FIG. 16.

Fig. 18 is a perspective view of another embodiment of a fan wheel according to the invention, which is assembled from 7 segments of FIG. 19 and an axial fan without rotating cover ring.

19 is a perspective view of a segment of a fan wheel according to FIG. 18.

20 is a perspective view of another embodiment of a fan impeller according to the invention, which is assembled from 11 segments according to Fig.21 and is a Nachleitrad.

21 shows a perspective view of a segment of a fan wheel according to FIG.

22 in a lateral plan view of a cutout at the edge of a

Segmentes of an embodiment of a fan wheel according to the invention Details on the design of the segment edge. FIG. 23 is a perspective view of another embodiment of a fan wheel according to the invention, which consists of 7 segments according to FIG. 24 is joined and a Axiallüfterrad with circumferential cover ring and an intermediate ring is, and in which wings between hub ring and intermediate ring and wings between the cover ring and intermediate ring in shape and number differ.

FIG. 24 is a perspective view of a segment of the fan wheel according to FIG. 23. FIG.

25 shows an enlarged view of an embodiment of a cross section through a joining region of fan wheels according to the invention, which does not have any design which enlarges the joining surfaces,

Fig. 26 in an enlarged view and in cross section another

 Embodiment of the joining region of the fan wheel, which is designed in a manner enlarging the joining surfaces,

27a shows an enlarged view of an embodiment of a cross section through a joining region of fan wheels according to the invention, which has a configuration which enlarges the joining surfaces in the form of an asymmetrical tongue and groove joint,

Fig. 27b shows an enlarged view of an embodiment of a cross section through a joining region according to the invention fan wheels, which has a joining surfaces enlarging design in the form of an asymmetric tongue and groove joint with local thickening of the wall thickness.

In the following, fan wheels are described which are made of plastic. stand and in particular have large sizes and are suitable for high speeds. Fan wheels are here understood to mean both stationary and rotating elements of fans with a guiding function for a flow medium, which essentially consist of 2 to 40 vanes, which are connected to one another in the circumferential direction by one, two or more rings. Fan wheels may be, for example, radial fan wheels, diagonal fan wheels, axial fan wheels, as well as front or Nachleiträder (stators). The fan wheels are made up of mutually identical or at least similar segments. As a result, expensive injection molding tools are not required. The production of the fan wheels is inexpensive. Despite the composition of the fan wheels of individual segments, they have a dimensional stability even at high speeds. The segments can, as will be explained with reference to subsequent embodiments, so firmly connected to each other that the composite fan high loads, such as speed loads, withstand.

The number of segments that make up a fan according to the invention preferably corresponds to the number of fan blades. In particular, with fan wheels having a large number of blades, two or more blades may be included in a segment, thereby reducing the number of segments. For all segments of the fan wheel only one injection molding tool is required, especially if the segments are identical to each other. If the segments are similar to one another, only a single injection molding tool is usually sufficient. The different design features of similar segments with each other can then be achieved either by exchangeable mold inserts in the injection molding tool or by subsequent processing of some injection-molded segments or the assembled fan wheel. The design of the segments and in particular the wings can be very flexible, since an injection molding tool for a segment compared to an injection molding tool for a complete wheel with much less restrictions can be designed. So For example, for an injection molding tool for producing a fan wheel in complete casting, a complicated slide mechanism often has to be used in order to be able to demould the blade channels, which is not necessary in an injection molding tool for producing a segment in advantageous embodiments. As a result, even hollow wings can be designed to save weight easily.

The individual segments are connected to one another by means of suitable joining methods for forming the respective fan wheel. Adhesive methods, laser welding methods, friction welding methods, induction welding methods, hot gas welding methods or ultrasonic welding methods are particularly suitable as joining methods. The joining areas between the adjoining segments can be selected relatively freely with regard to the operating voltages to be expected when using the fan wheel. The connection between the segments can be made solely by the described joining methods. Before geous it is, however, if in addition a form-fitting connection between the adjacent segments, which can serve both for additional strength and leadership in the manufacturing process.

The fan of FIG. 1 is a radial fan and is composed of the segments I to VI I. Fig. 2 shows one of these segments. Since in Fig. 2, the segment is shown only in plan view is, with respect to the spatial configuration of the segment in FIG. 12, which shows a different design of the segment, but from which the basic three-dimensional design of the segment emerges. In the embodiment according to FIG. 1, all segments I to VI I are the same, so that they are in the same

Injection molding tool can be produced.

The segment has a cover ring section 1, which has a curved outer edge 2 and an inner ring extending parallel thereto. curved edge 3 has. Both ends of the edges 2, 3 are connected by edges 4, 5 with each other. Seen in axial plan view, the edge 4 connects approximately at right angles to the outer edge 2. The opposite edge 5, viewed in axial plan view, at an acute angle to the outer edge 2 at. The edge 5 also includes an obtuse angle and the edge 4 at an acute angle to the inner edge 3 of the cover ring portion 1 at. The cover ring portion is, as shown in FIG. 12, curved over its rad iale width such that the radially inner edge 3 has a greater axial distance than the rad ial outer edge 2 of a hub ring portion 6. The hub ring portion 6 also has a radially outer edge 7 and a radially inner edge 8. Both edges 7, 8 are each curved and formed at their ends by edges 9, 10 with one another verbu. The hub ring portion 6 is radially inwardly over the cover ring portion 1 via. Seen in axial plan view, the outer edge 7 of the hub ring section 6 is congruent to the outer edge 2 of the cover ring section 1. In other embodiments of fan wheels according to the invention, in particular diagonal or Axiallüfterrädern, the externa ßere edge 7 of the hub ring portion 6 seen in axial plan view also offset and / or are at an angle to the outer edge 2 of the bezel section 1. The edges 9, 10 are, viewed in axial plan view of the segment, over a part of their length decku ngsgleich to the edges 4, 5 of the cover ring portion first This feature enables a particularly simple joining process. In other embodiments of the present invention, such a congruent configuration of the edges 9, 10 is not possible, for example when the wing is severely sacculated or twisted.

Between the cover ring portion 1 and the hub ring portion 6, a wing 1 1 extends, which is curved in the embodiment over its length and has the profile of a wing in cross section. The wing 1 1 is connected with its cover ring-side end 91 with the cover ring portion 1 and connected with its hub ring-side end 96 with the hub ring 6. The downstream end 12 of the 1 wing 1 runs approximately at an acute angle, while the inflow-side end 13, seen in plan view, is rounded arcuate (Fig. 2).

The wing 1 1 extends with its downstream end 12 to close to the edge 5 of the cover ring section. 1 With its inflow-side end 1 3, the wing 1 1, seen in axial plan view, projects beyond the cover ring section 1 and ends at a small distance from the edge 9 of the region of the hub ring section 6 projecting beyond the cover ring section 1.

Deviating from the illustrated embodiment, the wing 1 1 can also have a different cross-sectional configuration and / or a different extent. The wing 1 1 can not only be formed curved over its length, but also be designed to be tortuous over its length.

The hub ring portion 6 has near its inner edge 8 at least one passage opening 14. It is advantageous about half the width of the protruding hub ring portion 6 and serves to pass through Befestigungsg screws, with which the fan can be mounted in the installed position on a hub of a drive motor.

The hub ring portion 6 may be formed flat. However, it is also possible, as can be seen for example from FIG. 12, that the hub ring section 6 extends angled or bent at the outer end. In other embodiments of the invention, in particular diagonal wheels, the hub ring portion 6 may extend conically or curved over its entire or part of its extension.

In the assembled state to an impeller (FIG. 1), the edges 4 and 5 of the respective cover ring sections and the edges 9 and 10 of the respective hub ring sections lie together from respectively adjacent segments. Make the whole impeller Pairs of adjacent edges 4 and 5 joining areas 1 5 (on the top side) and pairs of adjacent edges 9 and 10 joining areas 16 (on the hub side). In order to ensure gapless contact of the edges 4 and 5 and 9 and 10 to joint regions 15 and 16, the curvature profiles of the edges 4 and 5 and the edges 9 and 10 of the respective adjacent segments must be substantially identical. The joining areas 15 and 16 extend transversely to the circumferential direction. In the illustrated embodiment of a radial fan, the joining areas 15 and 16 also extend transversely to the axis of the fan wheel. Since the wing 1 1 ends at a distance from these joining areas 15, 16, arise on the wing 1 1 as a result of the production of segments no additional burrs, edges and the like. The cover ring sections 1 of the segments I to VI I form the assembled cover fan the entire cover ring 1 ^* , accordingly form the Nabenringabschnitte 6 of the segments I to VI I together the hub ring 6 *.

The fan wheel, which is shown in perspective in FIG. 16, is an axial fan wheel with cover ring 1 *, hub ring 6 * and an intermediate ring 71 * and is likewise composed of segments I to VI I. The construction of segments is in the essential, the invention mainly characteristic points the same as that of the radial fan wheel of FIG. 1.

Fig. 17 shows one of the segments of the axial fan shown in Fig. 16, in which all the segments I to VI I are formed the same, so that they can be manufactured in the same injection molding tool.

The segment I shown in FIG. 17 has a cover ring section 1 which has a curved edge 2 lying downstream with respect to the main flow direction of the axial fan and a rim 3 extending parallel thereto and axially offset upstream. Both ends of the edges 2, 3 are connected by edges 4, 5 with each other. The NA- Benringabschnitt 6 also has a downstream edge 7 and an upstream edge 8. Both edges 7, 8 are each curved and connected at their ends by edges 9, 10 together. The hub ring section 6 lies radially completely within the cover ring section 1. The axial extension of hub ring 6 * and cover ring 1 * is identical in the embodiment shown, but may also be different depending on the blade geometry in other embodiments of axial fan wheels.

I n seen radial direction between the cover ring 1 * and hub ring 6 * is still an intermediate ring 71 * present in the embodiment of Figure 16. Such an intermediate ring helps to even higher strength of the assembled fan wheel. In an advantageous embodiment, an intermediate ring also advantages in air performance, efficiency and the acoustics of the fan can be achieved. One or more intermediate rings 71 ^* may be present on all types of fan wheels, such as radial fans, diagonal fans, or idler or idler gears. Due to the way in which segments are manufactured, it is possible to realize intermediate rings with less effort with regard to tool design than with production in complete casting.

The segment I shown in Figure 1 7 has accordingly an intermediate ring portion 71, which has a curved, lying downstream with respect to the Hauptströmungsrichtu ng of the axial fan edge 72 and a parallel thereto, axially upstream offset edge 73. Both ends of the edges 72, 73 are interconnected by edges 74, 75.

The edges 74, 75 of the intermediate ring portions 71 of the respective segments form the joined fan impeller areas 85 (Fig. 16), which extend transversely to the circumferential direction of the impeller and with which adjacent segments I to VI I abut each other. Since the wing 1 1 terminates at a distance from these joining areas 85, no wing 1 1 due to the intermediate ring 71 ^* arise on the wing. additional burrs, edges and the like. The intermediate ring sections 71 of the segments I to VII form the entire intermediate ring 71 * when the fan is assembled.

Between the cover ring portion 1 and the hub ring portion 6, a wing 1 1 extends, which is curved in the embodiment of Figure 16 with segments of Figure 17 along its length and twisted and has the profile of a wing in cross section. The downstream end 12 of the wing 1 1 runs as in the previous embodiment approximately at an acute angle, while the inflow-side end 13, seen in cross section through the wing 1 1, is rounded arcuately, as in the embodiment of FIG. 2 is shown.

The wing 1 1 of the embodiment with segments of FIG. 17 extends with its downstream end 12 to close to the edge 2 of the cover ring portion first With its upstream end 13, the wing 1 1 extends close to the edge 3 of the bezel section. 1

Deviating from the illustrated embodiment, the wing 1 1 can also have a different cross-sectional configuration and / or a different extent.

The hub ring portion 6 has no device on the impeller segment I according to FIG. 17, which serves for fastening the impeller to a motor. The fan formed from such segments of FIG. 16 can be attached by pressing, clamping, gluing, welding or the like to a motor. Of course, in other embodiments of axial fan segments, holes or the like may be provided for later attachment of the fan to a motor.

The hub ring section 6, the cover ring section 1 and the intermediate can ring portion 71, in particular in a Axiallüfterrad be cylindrical. However, it is also possible, as shown in the embodiment of FIG. 20 with reference to the cover ring 1 *, that the hub ring section 6 and / or the cover ring section 1 and / or the intermediate ring section 71 follow a more complicated, three-dimensional contour following which, in particular, the flow conditions can be better adapted.

FIG. 23 shows an axial fan impeller according to the invention, which is produced from segments according to FIG. I n this embodiment with hub ring 6 *, cover ring 1 * and intermediate ring 71 * extend between the cover ring 1 * and intermediate ring 71 * wing 1 1 1, which differ in shape and / or position and / or number of wings 1 12, the extending between intermediate ring 71 * and hub ring 6 *. As a result, in embodiments with an intermediate ring, the number of blades and the blade geometry can be better adapted to the respective flow conditions. Accordingly, in embodiments with a plurality of intermediate rings 71 *, even more variability can be brought into the design of the wings.

The segments of the axial fan wheel shown in Fig. 24 shown in FIG. 23 has the cover ring portion 1, the intermediate ring portion 71 and the hub ring portion 6, from which the cover ring 1 *, the intermediate ring 71 ^* and the hub ring 6 ^* are produced. This segment has two wings 1 1 1, which connect the cover ring portion 1 with the intermediate ring portion 71, and a wing 1 12, which connects the intermediate ring portion 71 with the hub ring portion 6.

The embodiment of a Axiallüfterrades, which is shown in perspective in Fig. 18, is an axial fan without cover ring and without intermediate ring and is also composed of mutually identical segments I to VI I, of which in Fig. 19, the segment I is shown. The construction of segments is similar to the construction of the embodiment already described in FIG. 1 6. However This axial fan does not have a cover ring, as is often the case with axial fans, in order to save weight and reduce the flow resistance. Therefore remain as joining areas only the joining areas 16 on the hub ring 6 *, which must take a higher load in this embodiment. The segment I has the hub ring section 6 and the wing 1 1.

The embodiment according to FIG. 20 with the segments according to FIG. 21 is an operating fan (stator). Stators can be pre or idler wheels in a fan. With regard to the construction of segments, however, there are no significant differences. In many applications, stators are also highly stressed parts to which the fan is attached with its motor and which are particularly stressed by the vibrations and vibrations of the fan during operation. The stator according to FIG. 20 is constructed from 1 1 identical segments I to XI of FIG. 21 in the manner according to the invention. The edges 4, 5, 9, 10 of the cover and hub ring sections 1, 6, which extend mainly in the axial direction, have a more complicated course, which has inner edges and corners. The hub ring 6 ^* is still provided downstream with a flat flange 61 ^* , which is formed by flange portions 61 of the segments I to XI and on which the fan motor can be attached later. Holes are not yet provided in the segments, since in the exemplary embodiment, a stator of 1 1 segments is constructed, which would mean an excessive number of holes. The holes can be drilled in the flange 61 ^* after assembly in this embodiment.

In particular with a large number of blades 1 1, it is also conceivable to have more than one wing in a segment, for example 2 - 4, which leads to a smaller number of segments. However, then the injection molding tool for making a segment becomes more complicated. In addition, the number of wings 1 1, if one wants to have only identical segments, by the number of Wings divisible per segment.

Depending on the loads to be expected during operation, it is advantageous for the fan wheels according to the invention to have additional intermediate rings 71 ^* in the circumferential direction in addition to the cover and hub ring 1 ^* , 6 *. One or more such additional rings may be in the area between the cover ring 1 * and hub ring 6 *. Its design with edges at the segments and joint areas in the assembled wheel is equivalent to the design of the cover and hub ring 1 *, 6 * according to the described embodiments. Spacer rings 71 ^* can bring additional stability, but also positively influence the flow (efficiency, acoustics). Such additional intermediate rings 71 ^* can be realized by the manufacturing principle of segments with relatively little effort.

To produce an advantageous embodiment of a fan impeller according to the invention, the segments I to VI I are initially arranged in a star shape (FIG. 15) and then pushed together approximately radially inwards until the segments I to VI I with their edges 4 and 5, 9 and 10, 74 and 75 lie together. At the resulting joint regions 1 5, 16, 85, the segments I to VI I are firmly connected to each other in the manner described, for example glued or welded. In this case, a high pressure is exerted on the segments I to VI I or on the joining regions 1 5, 16, 85 advantageously during the bonding or welding process, so that the adjacent segments I to VI I are firmly connected to each other. Similarly, the fan wheels, which have more than seven segments, are manufactured. The segments can be produced in simple injection molding tools, so that the production costs can be kept low. As the material for the segments I to VI I come the known, customary for injection molding fan wheels materials into consideration. Examples are short- or long-fiber-reinforced thermoplastics, such as polyamide (PA6, PA66, PA66 / 6, PAPA, PPA, PA 4.6, PA 12) or polyester (PBT, PET), polypropylene (PP), PPS, PES, PESU, PEEK, ABS, PC, ASA. Preference is given to using as materials for the segments polyamide, polypropylene or polyester.

Suitable reinforcing fibers for these materials are, for example, glass, carbon, aramid, thermoplastic (PET, PA) or natural fibers, for example flax, hemp, sisal, jute or coconut.

In embodiments in which adjacent segments by means of

Laser welding are connected, a high transparency of the plastic used for the laser light used is necessary. To achieve this, a polymer which is highly transparent to the wavelength of the laser light is used as the polymer. This can be achieved by special color pigments in the plastic. Of

Furthermore, it is advantageous to use special reinforcing fibers (in particular glass fibers) which have no or only very little

Refraction at the transition polymer to reinforcing fiber have.

This is possible by the use of a special adhesion-promoting coating on the surface of the glass fibers.

Excellent strengths for the segments and thus for the fan wheel arise when the reinforcing fibers in the injection molded segment I to VI I have lengths of about 50 pm to about 1 5 mm. A preferred range is between about 200 pm and 10 mm.

If the segments I to VI I are glued to one another at the joining regions 1 5, 16, 85, 1- or 2-component adhesives, such as polyurethane, acryl, methacrylates or silicones, can be used for this purpose. For bonding, solvent systems can also be used.

If the segments I to VI I are laser-welded together at the joining regions 15, 16, 85, diode lasers, CO2 lasers or NdYAG lasers can advantageously be used for this purpose. The connection of the segments I to VI I to the joining regions 15, 16, 85 can also be produced by friction welding, vibration welding or ultrasonic welding.

The connection of the segments I to VI I to the joining regions 1 5, 16, 85 can also be carried out by means of induction welding or hot gas welding. As a hot gas, for example, air, nitrogen or CO 2 come into consideration.

In both cases, the plastic is softened in the region of the joining regions 1 5, 16, 85. Under the pressure at which the segments I to VI I are pressed against one another at the joining regions 15, 16, 85, a material-locking connection of adjacent segments ensues which leads to a secure connection of the segments after the joining regions have cooled.

Since the wing 1 1 and the ring sections 1, 6, 71 are integrally formed with each other and form the segment, a simple, fast and cost-effective production of the fan is possible.

The fan as shown in FIG. 3 is similar to the fan of FIG. 1 and consists of the segments I to VI I. The wings 1 1 of the fan wheel are in turn arranged so that the joining areas 1 5, 16 extend with distance from the wings 1 1. As a result, the formation of burrs, edges or the like on the wings 1 1 is prevented, so that expensive rework can be omitted. While in the embodiment according to FIGS. 1 and 2, the segments I to VI I are connected with respect to loads which act in the circumferential direction, exclusively by a material connection or by an adhesive connection, the segments I to VI I in the embodiment of FIG. 3 additionally positively connected with respect to such loads. This positive connection is provided in the region of the edges 4, 5 of the cover ring sections 1 or the edges 9, 10 of the hub ring sections 6 of the segments I to VI I. The radially inward NEN over the cover ring portions 1 projecting portions of the hub ring sections 6 are formed the same as in the embodiment of Fig .1. The positive connection between adjacent segments I to VI I is designed so that the segments can not be separated from each other in the U starting direction. A release of the segments from each other in the non-bonded or non-welded state only possible that adjacent segments are moved in the axial direction of the fan against each other.

At the edge 5 of the cover ring portion 1 and on the, seen in the axial direction, underlying region of the edge 10 of the hub ring portion 6 is an approximately mushroom-shaped opening 1 7 is provided in each case. The opposite edge 4 of the cover ring portion 1 and, seen in the axial direction, underlying region of the edge 9 of the hub ring portion 6 are provided with a projecting mushroom-shaped projection 18 which engages in the opening 17 of the adjacent segment. The openings 1 7 and the projections 18 are formed complementary to each other so that they lie with their edges together. Due to the mushroom-shaped design, the openings 17 as well as the projections 18, seen in the circumferential direction, each provided with an undercut.

Deviating from the mushroom-shaped design, the form-fitting connections can also have other outline shapes. They merely need to be designed so that the adjacent segments I to VI I in the circumferential direction of the fan wheel can not be separated from each other.

The openings 17 and the projections 18 are respectively provided on the cover ring sections 1 and the hub ring sections 6. They can also be provided only on the bezel sections or only on the hub ring sections, depending on where on the respective fan high loads are to be expected. It can at one edge 4, 9 and 5, 10 over the length of several Openings 1 7 and complementary projections 18 may be provided. The wings 1 1 are arranged on the segments I to VI I that they have distance from the openings 17 and the projections 18.

For the purposes of the invention, a projection 18 is a protruding form-fitting part and an opening 7 is an at least approximately complementary recess on an edge 4, 9, 74 and 5. 10, 75.

Also in this embodiment, the integrally formed segments I to VI I are identical to each other, so that only a single injection molding tool for the segments is required. The interlocking elements 17, 18 provide an additional Introductio tion when joining the segments I to VI I and also provide additional dimensional stability under loads of the fan in the circumferential direction. Due to the form-locking elements 17, 1 8, the segments I to VI I are not star-shaped together amount to the fan, but in the axial direction.

The adjacent segments I to VI I are not only positively connected to the joining areas 15, 16, but also via an adhesive connection, a welded joint or the like, as has been described with reference to the previous embodiment. During the gluing or welding process, the adjacent n segments I to VI I are advantageously pressed firmly against one another so that the connection at the joining regions 1 5, 16 is optimal. Also in the region of the positive connection 17, 18 adjacent segments can be firmly connected to each other via the adhesive or welded connection.

C earhooks in the circumferential direction can be used in other embodiments of the invention in an equivalent manner to the described embodiment of FIG. 3 are also realized in Axiallüfterrädern, Diagonallüfterrädern or stators. Even with the intermediate ring sections 71 such form-fitting can be realized become. In these cases, too, there are restrictions on the joining process. H . The segments can not be brought together in the circumferential direction relative to one another.

The fan as shown in FIG. 4 also has the integrally formed seg ments I to VI I in the example. Again, they are the same design, so they can be made with only one injection molding tool. Similar to the embodiment of FIG. 1, the segments I to VI I are formed so that they can be arranged in a star shape and then pushed together, similar to that shown in FIG. 1 5 is shown.

The segments I to VI I are formed so that in addition to the joining regions 1 5, 16 on cover ring 1 ^* and hub ring 6 * even more joining regions 86 (Fig. 4) in the region of the wings 1 1 arise. This has the advantage that the bonding or welding surface for joining adjacent segments is increased in comparison to the previous embodiments. The segments I to VI I are designed so that only by assembling adjacent segments complete wings 1 1 are formed.

Fig. 5 shows one of these segments in a bottom view from the side of the hub ring section 6. It has the curved outer edge 7 and the gekrüm mten inner edge 8. The one end of the edges 7, 8 connecting edge 10 extends, seen in the axial direction, curved. The opposite, the other ends of the two edges 7, 8 connecting edge 9 is seen in the axial direction of the fan wheel, also curved over its length, with largely identical curvature as edge 10, so that adjacent, identical segments can be joined together without gaps. In direct connection with the two edges 9, 10, in each case one wing part 11a, 11b extends. The wing parts 11a, 11b extend between the hub ring section 6 and the cover ring section 1 (completely concealed in FIG. 5 by the hub ring section 6). If adjacent segments I to VI I with their edges 4, 5, 9, 10 juxtaposed, are the wing parts 1 1 a, 1 1 b with their edges 19, 20 to each other and thus form the wing 1 1, in this case is hollow. The adjoining impeller edges 19 and 20 of adjacent segments form an additional joining region 86. The wing 1 1 is otherwise the same design as in the embodiments according to FIG. 1 or FIG. 3. The wing 1 1 is also also in relation to the cover ring 1 * and the hub ring 6 * of the fan wheel also arranged the same as in these embodiments.

If adjacent segments I to VI I are connected to each other by an adhesive bond, then the adhesive is not only provided in the joint areas 1 5, 16 of the rings, but also in the joining region 86 of the wing 1 first This results in a very large adhesive surface, which ensures a solid and also high loads resistant connection between adjacent segments I to VI I. When adjacent segments are joined together by a welded joint to VI I, in this embodiment, the welding area is increased by the region of the joining region 86 of the wings 1 1, resulting in an increased load capacity.

Since the wings 1 1 are hollow, the fan has a relatively low weight. In addition, the hollow wings 1 1 have the advantage that they can be designed in terms of flow technology in a simple way channels for targeted secondary flows.

After the joining process, edges, burrs or the like may be present in the region of the joining regions 86 of the wings 86, but they can simply be removed in a conventional manner. The segments I to VI I are identical to each other and have in the axial plan view a center line 21 whose curvature is identical to the curvature of the edges 9, 10 in axial plan view. In this case, the measured width of the segment in the circumferential direction increases from the outer edge 2, 7 in the direction of the inner edge 8 in such a way that the segment in the region of the outer edge 2, 7 has the largest and in the region of the inner edge 8, the smallest circumferential width.

Due to the described design, the segments I to VI I, as shown schematically in FIG. 15, can be pushed together in a star shape and pressed against each other in the circumferential direction, so that the segments I to VI I at the joining regions 1 5, 16, 86 are firmly together. The tracks on which the segments are moved together in a rotationally symmetrical manner during the joining process must be carefully selected as a function of the course of the joining regions 15, 16, 86 in order to avoid undesired collisions. In particular, curved tracks are necessary in some embodiments.

Since Fig. 5 shows the segment in a bottom view, only the inner edge 3 can be seen from the cover ring section 1. The other edges 2, 4, 5 of the cover ring portion 1 are, seen in plan view of the segment, over its length congruent to the edges 7, 9, 10 of the hub ring portion. 6

6 shows, in plan view of the hub ring portion 6, a segment which is formed similar to the segment of FIG. 2. The wing 1 1 is provided on the segment, that its two outflow and inflow ends 12, 13 distance from the edges 4, 5, 9, 10 have. The wing 1 1 protrudes as in the embodiment of FIG. 2 radially slightly above the inner edge 3 of the cover ring section 1 before.

I m difference to the embodiment of FIG. 2, the wing 1 1 is hollow. The wing 1 1 is not continuous hollow. The cavity ends in the region of the cover ring portion 1, so that it is not broken through the cavity. The hollow formation of the wing 1 1 is achieved in the injection mold with the aid of a core slider. Due to this core slider, the wing 1 1 in the region of the hub ring portion 6 is open. In order to avoid noise development as well as dirt deposits within the wing 1 1 in use of the fan wheel, the wing 1 1 is advantageously closed after injection molding or after the joining process of the entire fan wheel with a lid or the like or filled with a material, for example foamed Material. The lid may be glued, welded or otherwise secured to the hub ring portion 6. This closure piece is advantageously designed so that it is flush with the outside of the hub ring portion 1 with its outer side. In order to achieve this, a recess must be provided on the injection-molded part in the region of the cavity at the hub ring section 6, into which the closure piece can be introduced flush with the surface.

Fig. 7 shows a segment which is basically the same design as the segment of FIG. 6. The difference is that within the hollow wing 1 1 at least one stiffener 22 is provided. The stiffener 22 is in the form of a web which extends between opposite side walls 23, 24 of the wing 1 1. The stiffening 22 advantageously extends over the entire axial height of the wing 11. The stiffener 22 provides additional strength of the wing 1 1.

In the injection molding tool 22, two core slides are provided to produce the web-shaped stiffening 22, which lie next to each other at a small distance, so that the web 22 is formed between the core slides during injection of the plastic.

In the exemplary embodiments according to FIGS. 1, 3 and 4, the joining regions 1 5, 1 6 between the segments I to VI I are not seen on a radial, in the axial direction of the fan wheel. Related to one Radial 60 (Figures 1, 3 and 4), which extends through the Schnittpu interface between the respective dividing line 15, 16 and the inner circular edge 8 of the fan, are the joining areas 1 5, 16 at an angle α to this radial 60th Depending on the course of the dividing lines 1 5, 16, the angle α increases in the direction from the inner edge 8 to the outer edge 2.

The segments I to VI I can also be designed so that the joining regions 1 5, 16 lie on the radial 60, so that the angle α is 0 °.

The angle α can be up to about 80 °, depending on the design of the segments I to VI I. This angular range is independent of how the segments I to VI I are interconnected.

Fig. 25 shows a possible design form of cross sections through joining areas 1 5, 16, 85, with which no effect enlarging the joining surface is achieved. It shows by way of example and in an enlarged representation a through a joining region 1 5, 16, 85 with adjacent segment edges 4, 9, 74 and 5, 10, 75 placed section AA (see Fig. 1, 3, 16, 18, 20). The course of the joining region 1 5, 16, 85 is in the section substantially that of a straight path which connects the inner side 30 with the outer side 31 of the ring sections 1, 6, 71 by the shortest route. The joining region 1 5, 16, 85 or the edges 4, 9, 74 and 5, 10, 75 of the segments I and II extend approximately perpendicular to the inner side 30 and to the outer side 31. This design form is the simplest form of design for a cross-section of a joint area. The associated tool design for the injection molding tool is simple and inexpensive. A joining region designed in this way also makes it possible for the segments I and II to be joined together in a direction transverse to the ring sections 1, 6, 71, as is necessary, for example, for the embodiment according to FIG. However, in this embodiment, the joining area 15, 16, 85 has a rather small area for gluing or welding, and there is no additional positive connection in the axial or radial direction between the segments made with each other. Also, no additional guidance is achieved during the joining process.

By way of example, FIGS. 8 to 11, 14 and 26 describe possible configurations of cross sections through joining areas 15, 16, 85 with which the joining surface can be considerably increased without the wall thicknesses of the rings 1 *, 6 *, 71 ^* enlarge, and with which an at least partial positive connection between adjacent segments I to VI I with respect to shifts in the axial and / or radial direction can be produced (joining surfaces enlarging designs). These FIGSu ren each show an example and in an enlarged view a through a joining region 1 5, 16, 85 with adjacent segment edges 4, 9, 74 and 5, 10, 75 placed section AA (see Fig. 1, 3, 16, 18, 20 ). In these examples, the joining surfaces are provided with enlarging designs which not only lead to an increase in the adhesive / welding surface, but additionally ensure increased dimensional stability of the assembled segments. For putting in addition, a guide is achieved by these special designs of the joining regions 1 5, 16, 85 when joining the segments I to VI I to the fan, so he facilitates the assembly of the segments to the fan. As a result, the manufacturing process of inventive fan wheels can be made significantly more economical, faster and more precise.

In an exemplary embodiment according to FIG. 8, an edge 4, 9, 74 of the segment I has a projecting spring 25 extending at least partially over the length (perpendicular to the plane of the drawing) of the segment

Rands 4, 9, 74 extends. An edge 4, 9, 74 may also have a plurality of springs 25 distributed over its length. The spring 25 tapers in the direction of its free end and lies approximately in half the thickness of the ring section 1, 6, 71.

An opposite edge 5, 10, 75 of a segment at least one corresponding groove 26 provided, in which engages the spring 25 of the respective adjacent segment. The groove 26 is formed complementary to the respective corresponding spring 25 and is also approximately half the thickness of the ring portion 1, 6, 71st In the mounted position, the spring 25 lies flat against the side walls and at the bottom of the groove 26. The joining region 15, 16, 85 formed by the two edges 4, 9, 74 and 5, 10, 75 of respectively adjacent segments has a very thin-surface shape. Between the edges 4, 9, 74 and the edges 5, 10, 75, an adhesive in the joining region 1 5, 16, 85 is introduced.

For the purposes of the invention, a spring 25 is a projecting form-fitting part and a groove 26 is an at least approximately complementary depression on an edge 4, 9, 74 or 5, 10, 75.

The spring 25 and the groove 26 are formed so that the ring portions 1, 6, 71 of the segments I, II abut each other, so that on the outer and inner side of the assembled rings 1 *, 6 *, 71 * no gap is formed.

For the sake of completeness it should be mentioned that an exchange of the features "groove" and "spring" with respect to the edges 4, 9, 74 and 5, 10, 75 equally within the meaning of the invention, which also applies mutatis mutandis to the embodiments of FIGS to 1 1, 14 and 26 applies.

In the embodiment of FIG. 9, the spring 25 is formed so that it has a small distance from the side walls and the bottom of the groove 26. As a result, a clearance 27 is formed in the joining region 1 5, 16, 85, in which a viscous adhesive 28 can be introduced. The joining region 15, 16, 85 has in this embodiment by the adhesive 28 completely or partially filled space 27 so far voluminous shape. This adhesive can be introduced into the groove 26 before joining the two segments I, II. The size of the free space 27, which after the completion of meneing the segments I and II is present, ensured by a stop 98, d. H. the segments I and II are moved toward each other until at least in the region of the stop 98 direct contact between the segment edges 4, 9, 74 and 5, 10, 75 is made. Alternatively, it is possible to introduce the adhesive after joining the two segments I and II perpendicular to the plane in the space 27.

In both described embodiments according to FIGS. 8 and 9, the adhesive is advantageously also applied to the areas of the stop 98, so that the adjacent segments I, I I are firmly connected to each other over a large area by the corresponding adhesive.

FIG. 10 shows a tongue-and-groove connection in which the connection of the segments I, II abutting one another with their edges 4, 9, 74 and 5, 10, 75 is effected via a rather linear weld in the region of the inner side 30 and 30, respectively The outer side 31 of the ring sections 1, 6, 71 is made. The weld is indicated by weld beads 29. The welded joint is provided in the region outside the groove 26, so that the segments I, I lie with their lying outside the groove 26 end faces in the region of the stopper 98 together. In addition, the spring 25 may be glued into the groove 26, as shown in FIG. 8 or 9 has been described.

In the embodiment of FIG. 1 1, the edges 4, 9, 74 and 5, 10, 75 of the segments I, II are stepped. Each segment edge 4, 9, 74 and 5, 10, 75 consists, seen in section, of a protruding mold part 25 ^* and a complementary to the protruding mold part 25 ^{* of} the adjacent segment recess 26 *. The gradations of the two edges 4, 9, 74 and 5, 10, 75 are formed complementary to one another, so that the segments I, II at the joining region 15, 16, 85 lie flat against each other. The joining region 1 5, 16, 85 has, seen in section, a perpendicular to the inside 30 and to the outside 31 of the ring sections 1, 6, 71 at-closing end face portions 32, 33 which by a

Wall portion 34 are interconnected. It advantageously extends obliquely at a slight angle with respect to the inside 30 and the outside 31 of the segments I, I I. The inclined wall portion 34 facilitates the joining of the adjacent segments I, I I. Advantageously, the transitions between the end face regions 32, 33 and the wall region 34 are rounded in order to avoid cracking.

An adhesive is applied to the end-face regions 32, 33 and the wall region 34, so that the two segments I, II are glued reliably flat to one another at the joining region 15, 16, 85. The step-shaped design of the joining regions 1 5, 16, 85 is advantageously provided over the entire length thereof.

The step-shaped design of the joining areas 1 5, 16, 85 also allows a simple and easy joining process in the manufacture of the fan.

In the embodiment according to FIG. 26, the effect increasing the joining surfaces is achieved in that the joining region 15, 16, 85, viewed in cross section, has acute angles with the inner side 30 or the outer side 31 of the annular sections 1, 6, 71 ß and ß *, which are significantly smaller than 90 °, advantageously between 70 ° and 30 °. If the joining region 15, 16, 85, viewed in cross section, is straight, β and β * have approximately the same amount. However, the joining region 15, 16, 85 can also run curved, as seen in section, as a result of which the amounts of the two angles .beta. And .beta. * Can also differ significantly from one another.

The cross-sectional configurations, in particular according to FIGS. 8, 11, 25 and 26, are also outstandingly suitable for embodiments in which the segments I, II are connected to one another by a flat weld. to be bound. An advantageous embodiment of the tongue and groove connection similar to FIG. 8 will be explained in detail with reference to FIG. 14, as it is well suited in particular for welded joints with laser welding, friction welding, vibration welding, hot gas welding or induction welding.

The ring sections 1, 6, 71 have a wall thickness D, which may be in the range between about 3 m m to about 12 mm. An advantageous range is between about 4 mm and about 8 mm. A particularly preferred wall thickness D is about 6 mm. The groove 26 has a depth t which is in the range of about (0.7 to 2.5) · D. Advantageously, the groove depth is about twice the wall thickness D.

The spring 25 tapers in its cross section in the direction of its free end 35. As a result, the spring 25 acts self-centering during the joining process. In addition, this cross-sectional taper is advantageous for strength. Near the free end 35, the spring 25 has the thickness d2, while near the stop 98 it has the greater thickness d1. The spring 25 lies with its side walls flat against the side walls of the groove 26. The end face 35 of the spring 25 has a small distance from the bottom 36 of the groove 26. This ensures that the two segments I, II can be joined together so that the flanks 39 and 40 of the spring 25 lie flat against the groove and that on the Inside 30 and the outside 31 of the rings 1 *, 6 *, 71 * no column arise.

Due to the cross-sectional taper of the spring 25, the cross-section of the groove 26 surrounding areas 37, 38 of the ring sections 1, 6, 71, seen from the free end of the groove in the region of the stop 98 starting, steadily increases. In the region of the cross-sectional thickness d2, the spring 25 is loaded only slightly, while the u-generating region 37, 38 of the groove of the segment II is heavily loaded. The correspondingly thick area 37, 38 can therefore safely absorb this load. In the cross-sectional area d 1, however, the spring 25 is very heavily loaded, so that the surrounding area 37, 38 of the groove of the segment II can be correspondingly weak.

The wedge angle between the two flanks 39, 40 of the spring 25 is advantageously in a range between approximately 0.5 ° and approximately 8 °.

The transition between the flanks 39, 40 of the spring 25 and the stop 98 is rounded off at the segment I with the radius R1. Advantageously, this radius R1 is approximately (0.05 to 0.3) .DELTA. The complementary radius R1 on segment II may be the same value or a slightly larger value to avoid premature collision of the segments I and II in the range of R1 to avoid during the joining process. As a result, a very small gap (not shown in FIG. 14) would arise in the region of R1.

However, it is advantageous to make this transition between the flanks 39, 40 and the stop 98 bionic, d. H. do not provide a constant radius in this transitional area. Advantageously, the curvature of the transition is designed such that the radius of curvature of the stopper 98 is small, and in the direction of the flanks 39, 40 is steadily larger. The bionic design of the transition has the advantage that, with regard to the force flow from the spring 25 into the ring section 1, 6, 71 of segment 1, it can be designed such that cracking is avoided.

The transition from the side walls of the groove 26 in the bottom side 36 of the groove 26 is rounded with the radius R2. It is advantageous (0, 05 to 0.3) · D. So that the power flow can be optimally ensured, the rounding in the transition region is designed in a particularly advantageous bionic, so no constant radius provided. Thus, this rounded transition can be optimally adapted to the loads occurring during use of the fan wheel so that cracking can be avoided in any case. Vorteilhafter- example, the curvature of the transition is designed such that the radius of curvature at the bottom 36 of the groove is small and in the direction of the flanks 39, 40 striding steadily larger.

I m completely merged state, ie. If the segments I and I I abut each other at the stop 98, in the region of the flanks 39, 40 there is advantageously a pre-stress already due to the compression of the segments I and I I in the joining process. This ensures that the flanks 39, 40 of the spring 25 and the corresponding flanks of the groove 26 after assembly without play together.

If the segments I, II are connected to one another by laser welding in the joining region 1 5, 16, 85 m, then, in an advantageous embodiment, a laser-absorbing layer is applied to the edges 4, 9, 74 and / or 5, 10, 75 before the joining process Liquid applied. After joining, during the welding process, the laser light which penetrates the specially used material of the ring sections 1, 6, 71 which is transparent to the laser light used is converted into heat in this region, as a result of which adjacent material melts and bonds cohesively. Since the absorbing liquid absorbs only a part of the laser light or is laser-transparent by the welding process itself, the spring 25 can be welded simultaneously with a single laser light source in the region of both flanks 39 and 40.

If the spring 25 is welded simultaneously with a single laser light source in the area of both flanks 39 and 40, it may be advantageous if a liquid of varying intensity absorbing the laser light is applied to the two flanks 39 and 40. On the flank 39 near the laser light source, a liquid which absorbs the laser light less strongly is then applied, while a liquid which absorbs the laser light more strongly is applied to the flank 40 which is remote from the laser light source. In this way, with respect to the flanks 39, 40 equal more moderate welding process can be adjusted.

If such a welding operation is carried out, as a material for the segments I to VI I advantageously a special, used for welding laser largely transparent plastic used. In an advantageous embodiment, the segments I-VI I are not machined, in particular in the region of their edges 4, 9, 74 and 5, 10, 75 and their immediate surroundings after the injection molding process, since the surfaces are otherwise laser light-reflecting laser light-absorbing and / or have laser light scattering properties. At the points to be welded, essentially the edges 4, 9, 74 and / or 5, 10, 75, a special laser-absorbing liquid is applied in the described manner before the welding operation. It ensures that the energy of the laser light is converted into heat precisely where it is needed so that the plastic in this area melts locally. This laser technique makes it possible to weld not only on the outer surface of the ring 1 *, 6 *, 71 ^* in the region of the inner side 30 and the outer side 31, but also in inner regions of the joining regions 1 5, 16, 85 of the material of the fan wheel.

In an advantageous embodiment, the segments I-VI I in the region of the inner side 31 and / or the outer side 30 in the immediate vicinity of the joining regions 15, 16, 85 have a particularly smooth surface. This can be achieved, for example, by polishing the corresponding regions of the injection molding tool. As a result, these surfaces have, to a lesser extent, laser-light-absorbing, laser-light-reflecting and / or laser-light-scattering properties, which has an advantageous effect on the coupling of the laser light into the joining regions 15, 16, 85 during the laser welding process.

An advantageous embodiment of the tongue-and-groove connection between adjacent segments I, II will be explained with reference to FIG. 27 a, which is designed similarly to the exemplary embodiment according to FIG. 14. The embodiment of FIG. Form of FIG. 27a is particularly well suited for laser welding connections between the two segments I, II. The segment I has as a form-fitting part the spring 25, whose upper side 30 of the ring section 1, 6, 71 facing flank 39 is firmly welded to the side wall of the groove 26 in the ring section 1, 6, 71 of the segment II. This design is advantageous if welding at the flank 40 of the spring 25 remote from the laser light source is impossible or only possible with difficulty, for example due to inadequate laser light transparency of the plastic used. This has the consequence that on the flank 40 no or only weak-bearing welded joint can be achieved by laser welding. A large part or even the complete power transmission therefore takes place via the flank 39.

For this reason, the flank 39 is equipped with a larger surface than the opposite flank 40. This has the consequence that the spring 25, in contrast to the embodiments according to FIGS. 8 to 10 and 14 not symmetrical, but asymmetric cross-section. This leads to an asymmetrical force transmission between the two segments I and II. The asymmetrical cross-sectional configuration of the spring 25 causes the regions 37, 38 of the ring section 1, 6, 71 of the segment II lying on either side of the spring 25 to be asymmetrical, in section as seen in FIG. 27a. A large part or the complete power transmission takes place via the region 37 belonging to the larger flank 39. For this reason, this region 37 has a substantially greater thickness than the opposite region 38, which is also substantially shorter than the region 37, measured transversely to the thickness direction of the segments.

The spring 25 in cooperation with the groove 26 fulfills the function of self-centering of the segments I and II during assembly to the fan. Due to the wedge angle between the two flanks 39, 40, the contact pressure necessary for laser welding is achieved during assembly in the region of the flank 39. Incidentally, the statements made with respect to the exemplary embodiment according to FIG. 14 also apply to this embodiment. The flank 39 connects at an obtuse angle to the stop 98, while the flank 40 connects approximately at right angles to the stop 98 'of the segment I or its edge portion 1, 6, 71. Due to the asymmetrical cross-sectional configuration of the spring 25, the two stops 98, 98 'are offset transversely to the thickness direction of the segments I, II, as shown in FIG. 27a. When merging the segments I and II are moved towards each other until they come in contact with each other in the area of the stops 98, 98 '. In the area of the stops 98, 98 ', an adhesive may be provided, so that the joined segments I, II are firmly connected to one another not only by laser beam welding but also by an adhesive connection. The two stops 98, 98 'in each case connect at right angles to the upper side 30 or the lower side 31 of the segment I. The groove 26 as a recess in the segment II is formed approximately complementary to the spring 25, so that the mated segments I, II can be firmly connected reliably. In addition, this ensures a proper power transmission.

The stops 98, 98 'of the segment I form with the corresponding counter-attacks of the segment II, the joining region 15, 16, 85th

Fig. 27b shows a similar construction of the tongue and groove connection as Fig. 27a. This compound is also particularly well suited for laser welding connections. In order to increase the area of the mainly force transmitting edge 39 of the spring 25 and the mainly force transmitting area 37, in the region of the joining region 15, 16, 85, the wall thickness is greater than in the area outside of this joining region. For this purpose, the underside 31 of the ring portion 1, 6, 71 of the segment I bent bent, while the top 30 is flat.

In the same way, the underside 31 of the ring portion 1, 6, 71 of the segment II is formed bent in the joint area, whereby the wall thickness increases in the joint area. In the area outside the joining The segments I, II have the wall thickness D. Within the joining region, the wall thickness D _{max of} the segments I, II is greater than the wall thickness D in the region outside the joining region. Advantageously, the wall thickness D _max in the range of 1, 05 to 1, 2 times the wall thickness D.

The region 38 of the segment II, which merely serves for centering and for applying the contact pressure during the joining process, protrudes beyond the remaining course of the underside 31.

The described design of the tongue and groove connection makes it possible to increase the contact pressure on the flank 39 of the spring 25 in the joining process by applying a pressure or a force on one side to the top 30 in the joining region 15, 16, 85. The segments I, II are clamped away from the joining region 15, 16, 85.

Incidentally, this embodiment is the same as the embodiment according to. Fig. 27a. This also applies to the embodiment according to FIG. 27b, the statements relating to the embodiments of FIGS. 14 and 27a.

Fig. 12 shows a perspective view of another embodiment of a segment for the production of the fan wheel. From Fig. 12 shows the basic structure of the previously described segments. The integrally formed segment has the wing 1 1, which extends between the cover ring portion 1 and the hub ring portion 6. The cover ring portion 1 has seen the curved outer edge 2 and the curved inner edge 3, in plan view. In this embodiment, the outer edge 2 is provided with a bend 41 which extends over the U mfangslänge of the cover ring portion 1.

The bezel section 1 is curved upward at a distance from the bend 41 such that the inner edge 3 has a greater axial distance from the hub ring section 6 than the outer edge 2. The cover ring section 1 has the two edges 4, 5. The hub ring portion 6 has the curved outer edge 7 and the inner curved edge 8. At its two ends, the edges 7, 8 by the edges 9, 10 are interconnected. In the region of the outer edge 7 of the hub ring portion 6 is opposite to the cover ring portion 1 slightly angled. Incidentally, the hub ring portion 6 is formed flat.

The edges 4, 9 are provided with the springs 25, as it is with reference to FIG. 8-10 and 14 has already been described. Accordingly, the edges 5, 10 are provided with the grooves 26. The springs 25 are interrupted by recesses 42, the grooves 26 are also interrupted by the recesses 42 complementary areas 43. The mutually complementary Aussparu lengths and areas 42, 43 are designed so that the assembly is facilitated. In the assembled state, an additional form fit in the longitudinal direction of the joining region 15, 16 is achieved by the recesses 42 and regions 43. In addition, the recesses and regions 42, 43, by virtue of their obliquely tapering shape, ensure that adjacent segments correctly position themselves relative to one another during the joining process (centering effect).

Seen in plan view of the segment, it has - except for the configuration of the edges 4, 9, 74 and 5, 10, 75 - the same outline shape as the segment of FIG. 2. Therefore, with respect to the arrangement of the edges of the cover ring portion 1 and the hub ring portion 6 reference may be made to the local statements.

Fig. 22 shows a lateral plan view and an enlarged view of a section of a segment edge 4, 9, 74. In this exemplary embodiment, the springs 25 are provided on the edge 4, 9, 74, their cross-section being similar to that described with reference to FIGS. 8-10 and 14 can be designed. Along the edge 4, 9, 74 are at approximately constant intervals U interruptions 44 between the springs 25th available . The groove (not shown) of the neighboring segment can in this case be designed continuously, that is without interruptions. The technical advantage achieved with these interruptions is that the flexibility of the springs 25 with respect to small displacements transverse to the ring sections 1, 6, 71 is greater, which is in the joining process for compensating for tolerances in the direction transverse to the ring sections 1, 6, 71 brings benefits. The distance a between two interruptions 44 in the longitudinal direction is advantageously between 0.5 times the spring depth t and 5 times t. At the foot of a recess between adjacent springs 25, a rounding is advantageously provided between two adjacent springs 25, which may be a complete rounding or else bionic, ie. can be designed with non-constant radius.

Fig. 13 finally shows in axial section one half of a radial fan. It is reinforced by three bands 54 to 56 extending over its circumference. The bands are advantageously applied under pretension on the fan. The bias may be in a range between about 10 N and about 10 kN, preferably about 10 to 100 N / m m 2 band cross-sectional area.

In the exemplary embodiment, the fan has three bands 54 to 56. Depending on the size of the fan, only one, two or more than three bands may be provided. The number of bands can be between 1 and 10. For tapes 54 to 56, thermoplastics are preferably used, such as polyamide (PA6, PA66, PA66 / 6, PAPA, PPA, PA4.6, PA12), polyester (PBT, PET), polypropylene (PP), PPS, PES, PESU , PEEK, ABS, PC, ASA and the same. Preferably, a polyamide, a polypropylene or a polyester is used as the material for the tapes.

For tapes 54 to 56, it is also possible to use thermosets, such as epoxy resin, urea resin or phenolic resin. Preferably, an epoxy or phenolic resin system is used as the thermoset. The bands 54 to 56 are advantageously reinforced with fibers, regardless of whether they consist of a thermoplastic or a thermoset. As reinforcing fibers are glass, carbon, Aram id, thermoplastic (PET, PA) or natural fibers into consideration, such as

Flax, hemp, sisal, jute or coconut.

The fibers are preferably continuous fibers which are simple and inexpensive. They can be easily introduced into the plastic mass of bands 54 to 56.

The bands 54 to 56 extend over the circumference of the fan wheel and are suitably attached to it. Thus, the bands 54 to 56 may be connected to the fan by welding. For the welding process diode lasers, but also other laser systems, can be used. If the segments are made of substantially laser-transparent material, in an advantageous embodiment, a laser-absorbing liquid is applied in the region of the tapes 54 to 56 to be welded on before the laser welding. To the

Welding can also be used ultrasound. It is also possible to produce by friction in the circumferential direction a firm connection between the bands and the fan.

As a further possibility for connecting the bands 54 to 56 with the fan and adhesive bonding come into consideration. Suitable adhesives are 1 or 2K adhesives, such as polyurethane, acrylic, methacrylates or silicones, or solvent systems.

The connection between the bands 54 to 56 and the fan wheel can also be made by being wrapped with a thermosetting thermoset, which cures after wrapping. As a result, a secure fixed connection between the respective band 54 to 56 and the fan is achieved. In the illustrated embodiment, the cover ring 1 ^* along its outer edge 2 is provided with a circumferential groove 57, in which the band 55 is inserted. The groove 57 is thus at the Au ßendurchmesser of the cover ring 1 ^* present.

Also on I inner diameter of the cover ring 1 * is a circumferential groove 58 which receives the band 54.

The hub ring 6 ^* is provided on the outside diameter with a circumferential groove 59 for the band 56.

All grooves 57 to 59 are open in the circumferential direction of the fan. As a result, the bands 54 to 56 can be easily inserted into the grooves 57 to 59. The grooves 57 to 59 can already be provided during the injection molding of the segments I to VI I. Each of these segments then has in its cover ring portion 1 and hub ring portion 6, the corresponding annular groove portions which form when joining the segments I to VI I d the circumferential over the circumference of the fan ring annular grooves.

The Nutenseitenwände lead the bands 54 to 56 in the axial direction, so that they can not slip off the fan.

The bands 54 to 56 may be wound several times over the circumference of the fan wheel. Advantageously, the tapes 54 to 56 are wound over the circumference of the impeller so often that the grooves 57 to 59 are completely filled with the tape.

In principle, however, it is sufficient if the respective band 54 to 56 is wound only once over the circumference of the fan wheel, the two ends of the band overlapping one another. The overlap is advantageously at least 10 bands wide to a maximum of 20% of the circumference. With such a design, it is advantageous if the respective band 54 to 56 has a width corresponding to the width. By the bands 54 to 56, the segments I to VII are held together firmly, so that even at high loads, for example, at high speeds and large diameters of the fan wheel, there is no risk that the segments separate from each other.

Are the fan wheels provided with the described endless fiber reinforced bands 54 to 56, the fan wheels at higher

Limit speeds are operated.

The bands may also be provided in fan wheels, which are not made of segments, but are integrally formed. Even with such fan wheels, the advantageously wound with bias on the fan wheel bands 54 to 56 have an advantageous effect, in particular with regard to increasing the limit speed of the fan wheel.

The proportion of the fibers in the bands 54 to 56 can advantageously be between 10 and 65 percent by volume, preferably between 25 and 60 percent by weight.

Also Axiallaufräder, Diagonallaufräder or stators can be in the manner described with ribbons 54 to 56 advantageously on cover ring 1 ^* and / or hub ring 6 * and / or intermediate rings 76 ^* reinforced.

With blower wheels made of segments, the occurrence of weld lines can be completely avoided, as they inevitably occur in the injection molding of complete wheels. The injection molding of individual segments, especially in segments with only one wing 1 1, can be designed without the occurrence of weld lines. This vulnerability, which is difficult to control, can thus be avoided in fan wheels made of segments. The strength of the joining regions 15, 16, 85, which is realized by adhesive or welded joints, can be achieved with the described elements of the invention become .

The segments are each designed so that they can be merged in the same assembly process in a same or similar movement. In FIG. 15, the segments I to VI I are shown in the left-hand illustration in the initial state. The motion arrows for each segment show that they perform the same merging motion. This significantly simplifies and facilitates the assembly process. However, this type of merging is only possible with those segments which at their edges 4, 9, 74; 5, 10, 75 have no protruding positive locking elements, which cause a positive connection in the sense of origin U, as shown by way of example in Fig. 3. In this case, the segments must be joined together in the axial direction because of the projection 18 and the aperture 1. In this case, the common direction of movement of the segments may be the axial movement.

The fan wheel can be post-machined after the joining process. This is important, for example, if in certain areas of the fan a high Ru running accuracy is required. This is expedient, for example, for the grooves 57 to 59 (FIG. 13) for the bands 54 to 56. Also, a post-processing, for example, with regard to the centering diameter and the outer diameter of the cover ring 1 * and the hub ring 6 ^* necessary. The grooves 57 to 59 may not initially be provided in the segments I to VI I and introduced after the joining of the segments machined.

Claims

claims

1. fan wheel with distributed over the circumference arranged wings (11) which are interconnected in the circumferential direction via at least one ring (1 ^* , 6 *, 71 ^* ), wherein the fan from at least three integrally formed segments (I to VII) consists , each having at least one ring portion (1, 6, 71) of at least one ring (1 ^* , 6 *, 71 *) and either a wing (11) or at least a portion (11a, 11b) of wings (11) and to Fan are joined, in which at least the ring portion / the ring sections (1, 6, 71) with transversely to the circumferential direction of the fan lying, joining areas (15, 16, 85) forming edges (4, 9, 74 and 5, 10, 75) lie against one another,

characterized in that at least one edge (4, 9, 74 and 5, 10, 75) of a ring portion (1, 6, 71) of each segment (I to VII) with at least one protruding mold part (25, 25 ^* , 18) and at least one edge (4, 9, 74 and 5, 10, 75) of a ring section (1, 6, 71) of each segment (I to VII) with at least one recess (25, 25 *, 18) at least approximately complementary to the form-fitting part (25). 26, 26 *, 17) is provided.

2. fan according to claim 1,

characterized in that the form-fitting part (25, 25 ^* , 18) tapers in the direction of its free end.

3. fan according to claim 1 or 2,

 characterized in that the recess as a groove (26) in the region between the upper side (30) and the underside (31) of the annular portion (1, 671) is arranged.

4. fan according to claim 1 or 2,

characterized in that the recess as part (26 ^* ) of a step to the top or the bottom (30, 31) of the ring portion (1, 6, 71) is open.

5. fan according to claim 4,

characterized in that the edge (32 to 34) of the ring sections (1, 6, 71) having the form-fitting part (25, 25 ^* , 18) and the recess (26, 26 *, 17) is stepped.

6. Fan according to one of claims 1 to 5,

characterized in that the recess (26, 26 ^* , 17) has a depth (t) which is in the range of about (0.7 to ^2.5 ) ^■ D, where (D) is the wall thickness of the ring portion (1, 6, 71).

7. fan wheel according to one of claims 1 to 6,

characterized in that the form-fitting part (25, 25 ^* , 18) bears against at least one side surface (39, 40) on one side wall of the depression (26, 26 ^* , 17).

8. fan according to one of claims 1 to 7,

characterized in that the transition of at least one side surface (39, 40) of the form-fitting part (25, 25 ^* , 1 8) in the edge (4, 9, 74 and 5, 10, 75) of the ring portion (1, 6, 71 ) is curved, preferably with a radius (R1), which is about 0.05 to 0.3 of the wall thickness (D) of the ring portion (1, 6, 71).

9. fan wheel according to one of claims 1 to 8,

 characterized in that the areas (37, 38) between the side walls of a groove (26) pronounced Vertiefu ng and the top and bottom (30, 31) of the ring portion (1, 6, 71) are about the same d ick.

10. fan wheel according to one of claims 1 to 8,

characterized in that the regions (37, 38) between the side walls of a groove (26) pronounced depression and the upper and U nterseite (30, 31) of the Ringabschn itte (1, 6, 71) under are different thick.

11. Fan according to one of claims 1 to 10,

 characterized in that the one side surface (39, 40) of a spring (25) pronounced form-fitting part is larger than the other side surface.

12. Fan according to one of claims 1 to 11,

characterized in that the wall thickness (D _max ) of the ring portion (1, 6, 71) in the region of the recess (26, 26 ^* , 17) is greater than the wall thickness (D) in the region outside the recess.

13. Fan according to one of claims 1 to 12,

 characterized in that the fan has at least one hub ring (6 *) which connects the wings (11) at their hub ring-side ends (96) in the circumferential direction with each other and to which the fan is connected to a drive motor.

14. Fan according to one of claims 1 to 13,

 characterized in that the fan has at least one cover ring (1 *), which connects the wings (11) at their cover ring-side ends (91) in the circumferential direction with each other.

15. Fan according to claim 14,

characterized in that the hub ring (6 ^* ) and the cover ring (1 *) are offset from one another and the wings (11) extend between the hub ring (6 *) and cover ring (1 *).

16. Fan according to one of claims 1 to 15,

characterized in that the fan wheel has at least one intermediate ring (71 *) which connects the wings (11) in the circumferential direction and is secured to the wings in the area between the lateral ends (96, 91) thereof, the segments (L-VII ) each have at least one intermediate ring portion (71).

17. Fan wheel according to one of claims 1 to 16,

 characterized in that the segments (I to VII) are formed at least approximately the same and are advantageous injection molded parts.

18. Fan according to one of claims 1 to 17,

 characterized in that the edges (4, 9, 74; 5, 10, 75) of the ring sections (1, 6, 71) are substantially congruent to one another and form joining regions (15, 16, 85) with which adjacent segments (I to VII) lie flat against each other.

19. Fan impeller according to one of claims 1 to 18,

 characterized in that adjacent segments (I to VII) by means of gluing and / or welding to the joining areas (15, 16, 85) are interconnected.

20. Fan according to claim 18 or 19,

 characterized in that cross-sections through the joining regions (15, 16, 85) are designed in a manner enlarging the joining surfaces.

21. Fan according to one of claims 1 to 20,

 characterized in that the upstream and downstream ends (12, 13) of the wings (11) are spaced from the joining areas (15, 16).

22. Fan impeller according to one of claims 1 to 20,

 characterized in that joining regions (86) extend through the wings (11).

23. Fan according to one of claims 19 to 22,

characterized in that the segments (I to VII) are connected to each other by means of laser welding, induction welding or hot gas welding.

24. Fan, in particular according to one of claims 1 to 23, characterized in that the fan is wound on at least one ring (1 *, 6 *, 71 *) with at least one reinforcing tape (54 to 56), made of thermoplastic or thermosetting plastic can exist.

25. Fan according to claim 24,

 characterized in that the reinforcing band (54 to 56) reinforcing parts, preferably quasi endless Verstärku ngsfasern contains.

26. Fan according to claim 24 or 25,

 characterized in that the reinforcing band (54 to 56) is fixed to a ring (1 *, 6 *, 71 *) of the fan wheel by welding or gluing.

27. Fan according to one of claims 24 to 26,

characterized in that at least one ring (1 ^* , 6 ^* , 71 ^* ) of the fan wheel for receiving the reinforcing strip (54 to 56) with at least one circumferential groove (57 to 59) is provided.

28. Fan wheel according to one of claims 24 to 27,

 characterized in that the fan wheel is integrally formed.