EP3198151B1 - Segmented fan wheel - Google Patents

Description

The invention relates to a fan wheel 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 upstream guide or trailing guide wheels (stators) of fans.

Fan wheels are made of different materials. For example, they can be made in one piece from fiber-reinforced plastics. Such a fan wheel manufacture has proven itself up to a certain outer diameter. For larger sizes, however, the required investment in injection molding tools and the price of parts increases so much due to the high machine sets for large injection molding machines that implementation is no longer profitable. In addition, the cylinders of the injection molding machines are usually not able to heat more than 15 kilograms of molten fiber-reinforced plastic to sufficiently high temperatures. For this reason it is also known to manufacture such fan wheels from several parts. So it is known ( DE 41 39 293 A ), box-shaped or U-shaped segments to be put together materially and form-fittingly and to apply a hub ring and a cover ring to the top and bottom of these assembled elements by gluing or welding. Due to the large number of individual parts, the production of such impellers is complex, time-consuming and correspondingly expensive because the segments first have to be put together and the cover ring and hub ring have to be attached in further steps.

Fan wheels are also known in which the blades are detachably connected to a hub with which the fan wheel sits on a drive shaft ( DE 10 2009 008 508 A1 ).

Fan wheels are also known ( WO 20012/131617A1 ), in which the wings are designed in the form of hollow segments. They are placed together and then held together by a washer and cap that attaches to the top and bottom of the assembled wing segments. Such fan wheels can only be manufactured and assembled with great effort. The wing segments must first be assembled and positioned. Only then are the disk and the cap placed on the two sides of the assembled wing segments and fastened to them.

Fan wheels are also known ( US2003/0235502A ) composed of block-shaped segments. The block-shaped inner and outer parts, which form cylindrical outer and inner rings, abut one another with their axially extending surfaces. Such fan wheels are very heavy and are only suitable for special applications.

From the DE 25 35 196 A1 a fan wheel according to the preamble of claim 1 is known.

The invention is based on the object of designing the generic fan wheel in such a way that it can be produced inexpensively and easily. The fan wheel should only have a low weight and be able to withstand high loads, in particular high speeds.

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

In the case of the fan wheel according to the invention, the area of the joining areas is enlarged by the protruding form-fitting part and the associated depression, as a result of which the fan wheel composed of the segments is given a high degree of stability and strength. A design that enlarges the joining areas differs from a conventional design in that the cross section through the joining areas does not approximately have the shape of one of the two walls of the ring has a short, straight connecting stretch that is approximately perpendicular to the walls. If the segments are connected to one another by means of adhesive, the adhesive surface is increased by the design that increases the joint surface, which leads to an increase in the strength of the fan wheel. This also applies if adjacent segments are welded to one another over a large area at the joining areas. In addition, this design, which enlarges the joining surfaces, forms an additional form-fitting connection between adjacent segments, as a result of which the segments are prevented from shifting relative to one another transversely to the circumferential direction. In addition, such a configuration can make it easier to join the segments together in the manufacturing process, since the guide elements form an additional guide for adjacent segments relative to one another. The interlocking parts and the indentations form a tongue and groove connection, which leads to a secure connection of the segments. During the manufacturing process, adjacent segments are joined together axially or radially or a combination of axially and radially, so that the protruding form-fitting part reaches the recess of the subsequent ring section section of the adjacent segment. With the design according to the invention, the joining surface is increased considerably without increasing the wall thickness of the ring sections. As a result of the design according to the invention, the manufacturing process of the fan wheels according to the invention can be designed very economically, quickly and precisely.

In the case of the fan wheel according to the invention, one-piece segments are used which have ring sections and fan blades or fan blade sections. The ring sections run essentially 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 adjacent segments are connected to 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 can in particular be hub rings or cover rings which connect the vanes at their lateral ends to one another in the circumferential direction, or intermediate rings which are connected to the vanes in their intermediate regions between their lateral ends. The hub ring is advantageously used to connect the fan wheel to a drive motor. In the case of stators, the cover ring is advantageously used to attach the stator to another device.

The form-fitting part tapers towards its free end. This greatly simplifies the joining of adjacent segments.

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

In a variant not claimed, the recess is open to the top or bottom of the ring section. Such a design enables a simple and problem-free joining process when manufacturing the fan wheel. Since the recess is open on one side of the edge section, adjacent segments can be very easily placed together in the axial direction of the fan wheel during manufacture.

In such a case, the edge of the ring sections having the form-fitting part and the recess is advantageously of stepped design. Such elements can be produced very simply in terms of manufacturing technology.

It is advantageous if the depression has a depth which is approximately 0.7 to 2.5 times the wall thickness of the ring section.

In a preferred embodiment, the form-fitting part rests with at least one of its side faces on the side wall of the depression. It is advantageous if the form-fitting part bears against the side walls of the depression with both side faces. Then adjacent segments are securely connected to each other.

In principle, however, it is also possible for there to be a free space between the side surfaces and/or the end face of the form-fitting part and the side walls and/or the base of the depression.

The spacing of the form-fitting part from the side walls and/or from the bottom of the depression leads to a free space into which, for example, a viscous adhesive can be introduced. This adhesive can be introduced into the recess before the segments are joined together.

According to the invention, the transition of at least one side surface of the form-fitting part into the edge of the ring section is curved, preferably with a radius that is approximately 0.05 to 0.3 times the wall thickness of the ring section. The transition is advantageously bionic, i.e. without a constant radius. The bionic design has the advantage that the transition with regard to the flow of forces from the form-fitting part into the ring section of the respective segment can be designed in such a way that cracking is reliably avoided. In this way, the transition can be optimally adapted to the loads occurring when using the fan wheel.

In an advantageous embodiment, the areas of the ring section between the side walls of the recess and the top and bottom of the ring section are approximately the same thickness.

However, the ring section can also be designed in such a way that these areas between the side walls of the recess and the top and bottom of the ring section have different thicknesses. In this case, the area that makes little or no contribution to power transmission when the fan wheel is in use can be made thinner than the opposite area.

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

In order to further increase the area that transmits the force when the segments are joined to the fan wheel, the wall thickness of the ring section in the area of the depression is advantageously greater than the wall thickness in the area outside of the depression.

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

The cover, hub and intermediate ring sections of adjacent segments are preferably designed in such a way that their edges lying transversely to the circumferential direction lie essentially congruently on one another and form joint areas in pairs, with which adjacent segments lie flat on one another. This ensures a simple yet secure connection of the segments lying against one another.

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

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

A particularly advantageous embodiment of the fan wheel is that the inflow and outflow ends of the blades are at a distance from the joint areas of the fan wheel. In this case, only the edges of the ring sections running transversely to the circumferential direction of the fan wheel serve as connecting surfaces.

However, it is also possible that additional joining areas between adjacent segments run through the vanes. In this case, the complete wings are only formed by joining 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 advantageously injection molded parts that can be produced easily and inexpensively.

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 reinforcement parts, preferably reinforcement fibers.

The reinforcing fibers advantageously have lengths of approximately 10 μm to over 15 mm, preferably lengths of approximately 200 μm to approximately 10 mm. Reinforcement fibers of this type can be easily incorporated into the plastic and ensure high strength.

For example, 1- or 2-component adhesives or solvent systems can be considered as adhesives for connecting the segments to one another.

A further advantageous connection possibility consists in connecting the segments to one another by means of laser welding, induction welding or hot gas welding.

Particularly in the case of large diameters of the fan wheel, an advantageous embodiment consists in wrapping at least one ring around the fan wheel with at least one reinforcing band. It also holds the segments firmly together so that the fan wheel can also be used at higher speeds or under other high loads.

The reinforcement band can consist of thermoplastic or duroplastic and advantageously contain reinforcement parts, preferably reinforcement fibers.

Glass, carbon, aramid, thermoplastic or natural fibers are advantageously considered as reinforcing fibers.

The reinforcement 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 consists in attaching the reinforcement band to the circumference of one or more rings of the fan wheel by wrapping it with a hardening duroplast.

A particularly optimal design results when the reinforcement strip is wound onto the fan wheel under pretension. The fan wheel obtained in this way is characterized by high strength. A such a fan wheel can be used at high limiting speeds. In an advantageous embodiment, the prestressing of the reinforcement band is in the range between about 10N and about 10kN, preferably between about 10 and 100 N per mm ² cross-sectional area of the band.

Reliable fastening of the reinforcement strip on the fan wheel is ensured if the fan wheel is provided with a circumferential groove for receiving the reinforcement strip on the rings to be provided with reinforcement strip. The reinforcement band can be accommodated in it in such a way that it cannot slip off the fan wheel.

The fan wheel according to the invention can be a radial, an axial or a diagonal fan wheel as well as an inlet guide wheel or rear guide wheel (stator).

Fig. 1

in axialer Draufsicht ein erfindungsgemäßes Lüfterrad, das aus mehreren Segmenten gebildet ist.

Fig. 2

in vergrößerter Darstellung ein Segment zur Herstellung des Lüfterrades gemäß Fig. 1.

Fig. 3

eine axiale Draufsicht auf eine zweite Ausführungsform eines erfindungsgemäßen Lüfterrades, das aus mehreren Segmenten zusammengesetzt ist.

Fig. 4

eine Unteransicht einer weiteren Ausführungsform eines erfindungsgemäßen Lüfterrades, das aus mehreren Segmenten zusammengesetzt ist.

Fig. 5

in vergrößerter Darstellung ein Segment zur Herstellung des Lüfterrades gemäß Fig. 4.

Fig. 6und Fig. 7

jeweils weitere Ausführungsformen von Segmenten zur Herstellung eines erfindungsgemäßen Lüfterrades.

Fig. 8bis Fig. 10

jeweils in vergrößerter Darstellung unterschiedliche Ausführungen von Querschnitten durch Fügebereiche erfindungsgemäßer Lüfterräder, die in einer die Fügeflächen vergrößernden Art und Weise gestaltet sind.

Fig.11

eine nicht-erfindungsgemäße Variante eines Fügebereiches.

Fig. 12

in perspektivischer Darstellung eine weitere Austührungsform eines Segmentes zur Herstellung eines erfindungsgemäßen Lüfterrades.

Fig. 13

im Axialschnitt eine Hälfte einer weiteren Ausführungsform eines erfindungsgemäßen Lüfterrades.

Fig. 14

in vergrößerter Darstellung eine erfindungsgemäße Ausbildung von Querschnitten durch Fügebereiche zwischen benachbarten Segmenten.

Fig. 15

in schematischer Darstellung das Zusammenfügen der Segmente zu einem erfindungsgemäßen Lüfterrad.

Fig. 16

in perspektivischer Darstellung eine weitere Ausführungsform eines findungsgemäßen Lüfterrades, das aus 7 Segmenten gemäß Fig. 17 zusammengefügt ist und ein Axiallüfterrad mit umlaufendem Deckring sowie einem Zwischenring ist.

Fig. 17

in perspektivischer Darstellung ein Segment eines Lüfterrades gemäß Fig. 16.

Fig. 18

in perspektivischer Darstellung eine weitere Ausführungsform eines erfindungsgemäßen Lüfterrades, das aus 7 Segmenten gemäß Fig. 19 zusammengefügt ist und ein Axiallüfterrad ohne umlaufendem Deckring ist.

Fig. 19

in perspektivischer Darstellung ein Segment eines Lüfterrades gemäß Fig. 18.

Fig. 20

in perspektivischer Darstellung eine weitere Ausführungsform eines erfindungsgemäßen Lüfterrades, das aus 11 Segmenten gemäß Fig. 21 zusammengefügt ist und ein Nachleitrad ist.

Fig. 21

in perspektivischer Darstellung ein Segment eines Lüfterrades gemäß Fig. 20.

Fig. 22

in seitlicher Draufsicht auf einen Ausschnitt am Rand eines Segmentes einer Ausgestaltungsform eines erfindungsgemäßen Lüfterrades Details zur Gestaltung des Segmentrandes.

Fig. 23

in perspektivischer Darstellung eine weitere Ausführungsform eines erfindungsgemäßen Lüfterrades, das aus 7 Segmenten gemäß Fig. 24 zusammengefügt ist und ein Axiallüfterrad mit umlaufendem Deckring sowie einem Zwischenring ist, und bei dem sich Flügel zwischen Nabenring und Zwischenring und Flügel zwischen Deck- ring und Zwischenring in Form und Anzahl unterscheiden.

Fig. 24

in perspektivischer Darstellung ein Segment des Lüfterrades gemäß Fig. 23.

Fig. 25

in vergrößerter Darstellung eine Ausführung eines Querschnitts durch einen Fügebereich eines Lüfterrads, welcher keine die Fügeflächen vergrößernde Gestaltung aufweist,

Fig. 26

in vergrößerter Darstellung und im Querschnitt eine alternative, nicht-erfindungsgemäße Ausgestaltung des Fügebereiches des Lüfterrades, der in einer die Fügeflächen vergrößernden Art und Weise gestaltet ist,

Fig. 27a

in vergrößerter Darstellung eine Ausführung eines Querschnitts durch einen Fügebereich erfindungsgemäßer Lüfterräder, welcher eine die Fügeflächen vergrößernde Gestaltung in Form einer asymmetrischen Nut- und Federverbindung aufweist,

Fig. 27b

in vergrößerter Darstellung eine Ausführung eines Querschnitts durch einen Fügebereich erfindungsgemäßer Lüfterräder, welcher eine die Fügeflächen vergrößernde Gestaltung in Form einer asymmetrischen Nut- und Federverbindung mit lokaler Aufdickung der Wandstärke aufweist.

Im Folgenden werden Lüfterräder beschrieben, die aus Kunststoff bestehen und insbesondere große Baugrößen haben und für hohe Drehzahlen geeignet sind. Unter Lüfterrädern werden hier sowohl stehende als auch rotierende Elemente von Lüftern mit Leitfunktion für ein Strömungsmedium verstanden, die im Wesentlichen aus 2 bis 40 Flügeln bestehen, welche durch einen, zwei oder mehrere Ringe in Umfangsrichtung miteinander verbunden sind. Lüfterräder können beispielsweise Radiallüfterräder, Diagonallüfterräder, Axiallüfterräder, ebenso wie Vor- oder Nachleiträder (Statoren) sein. Die Lüfterräder werden aus untereinander gleichen oder zumindest ähnlichen Segmenten zusammengefügt. Dadurch sind teure Spritzgusswerkzeuge nicht erforderlich. Die Herstellung der Lüfterräder ist kostengünstig. Trotz der Zusammensetzung der Lüfterräder aus einzelnen Segmenten haben sie eine Formstabilität auch bei hohen Drehzahlen. Die Segmente können, wie anhand nachfolgender Ausführungsbeispiele noch dargelegt werden wird, so fest miteinander verbunden werden, dass das zusammengesetzte Lüfterrad hohen Belastungen, beispielsweise Drehzahlbelastungen, standhält.The invention is explained in more detail with reference to some embodiments shown in the drawings. Show it

1

in axial plan view a fan wheel according to the invention, the is made up of several segments.

2

in an enlarged view a segment for the production of the fan wheel according to 1 .

3

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

4

a bottom view of a further embodiment of a fan wheel according to the invention, which is composed of several segments.

figure 5

in an enlarged view a segment for the production of the fan wheel according to 4 .

6 and 7

each other embodiments of segments for the production of a fan wheel according to the invention.

8 to 10

each in an enlarged representation of different versions of cross sections through joint areas of fan wheels according to the invention, which are designed in a way that enlarges the joint areas.

Fig.11

a non-inventive variant of a joining area.

12

a perspective view of a further embodiment of a segment for the production of a fan wheel according to the invention.

13

in axial section, one half of a further embodiment of a fan wheel according to the invention.

14

in an enlarged representation of an inventive design of cross sections through joint areas between adjacent segments.

15

in a schematic representation of the joining of the segments to form a fan wheel according to the invention.

16

a perspective view of another embodiment of a fan wheel according to the invention, which consists of 7 segments according to 17 is assembled and is an axial fan wheel with a circumferential cover ring and an intermediate ring.

17

according to a perspective view of a segment of a fan wheel 16 .

18

a perspective view of another embodiment of a fan wheel according to the invention, which consists of 7 segments 19 is assembled and is an axial fan wheel without a circumferential cover ring.

19

according to a perspective view of a segment of a fan wheel 18 .

20

a perspective view of another embodiment of a fan wheel according to the invention, which consists of 11 segments according to 21 is assembled and is a guide vane.

21

according to a perspective view of a segment of a fan wheel 20 .

22

in a side plan view of a section at the edge of a segment of an embodiment of a fan wheel according to the invention, details of the design of the segment edge.

23

a perspective view of another embodiment of a fan wheel according to the invention, which consists of 7 segments 24 is joined together and is an axial fan wheel with a circumferential cover ring and an intermediate ring, and in which the blades between the hub ring and the intermediate ring and the blades between the cover ring and the intermediate ring differ in shape and number.

24

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

25

an enlarged view of a cross-section through a joint area of a fan wheel, which does not have a design that enlarges the joint surfaces,

26

in an enlarged view and in cross section, an alternative, non-inventive embodiment of the joint area of the fan wheel, which is designed in a way that enlarges the joint surfaces,

Figure 27a

in an enlarged view an embodiment of a cross section through a joint area of fan wheels according to the invention, which has a design in the form of an asymmetrical tongue and groove connection that enlarges the joint surfaces,

Figure 27b

in an enlarged view an embodiment of a cross section through a joint area of fan wheels according to the invention, which has a design enlarging the joint areas in the form of an asymmetrical tongue and groove connection with local thickening of the wall thickness.

Fan wheels made of plastic are described below and in particular have large sizes and are suitable for high speeds. Fan wheels are understood here to mean both stationary and rotating elements of fans with a guiding function for a flow medium, which essentially consist of 2 to 40 blades which are connected to one another by one, two or more rings in the circumferential direction. Fan wheels can be, for example, radial fan wheels, diagonal fan wheels, axial fan wheels, as well as upstream or downstream guide wheels (stators). The fan wheels are assembled from segments that are the same or at least similar to one another. This means that expensive injection molding tools are not required. The production of the fan wheels is inexpensive. Despite the composition of the fan wheels from individual segments, they have dimensional stability even at high speeds. As will be explained with reference to the following exemplary embodiments, the segments can be connected to one another so firmly that the assembled fan wheel can withstand high loads, for example speed loads.

The number of segments that make up a fan wheel according to the invention preferably corresponds to the number of fan wheel blades. In particular in the case of fan wheels with a large number of blades, a segment can also contain two or more blades, as a result of which the number of segments is reduced. Only one injection molding tool is required for all segments of the fan wheel, particularly if the segments are of identical design. If the segments are similar to each other, then usually only a single injection molding tool is sufficient. The different design features of the similar segments among one another can then be achieved either by interchangeable 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 vanes can be very flexible, since an injection mold for a segment can be designed with significantly fewer restrictions compared to an injection mold for a complete wheel. So For example, a complicated slide mechanism often has to be used for an injection molding tool for producing a fan wheel in complete casting in order to be able to demould the blade channels, which is not necessary with an injection molding tool for producing a segment in advantageous embodiments. As a result, hollow wings can also be easily designed to save weight.

The individual segments are connected to one another using suitable joining methods to form the respective fan wheel. Bonding methods, laser welding methods, friction welding methods, induction welding methods, hot gas welding methods or ultrasonic welding methods are preferably considered as joining methods. The joining areas between the adjacent 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 produced solely by the joining method described. However, it is advantageous if there is also a positive connection between the adjacent segments, which can serve both for additional strength and for guidance during the manufacturing process.

The fan wheel according to 1 is a radial fan wheel and is made up of segments I to VII. 2 shows one of these segments. there in 2 the segment is shown only in plan view, is related to the spatial configuration of the segment 12 referenced, which shows a different design of the segment, but which shows the basic three-dimensional design of the segment. In the embodiment according to FIG 1 all segments I to VII are of the same design, so that they can be produced in the same injection molding tool.

The segment has a cover ring section 1, which has a curved outer edge 2 and a curved inner edge running parallel thereto Edge 3 has. Both ends of the edges 2 , 3 are connected to one another by edges 4 , 5 . Seen in an axial top view, the edge 4 adjoins the outer edge 2 approximately at right angles. The opposite edge 5 adjoins the outer edge 2 at an acute angle, as seen in an axial plan view. The edge 5 also connects to the inner edge 3 of the cover ring section 1 at an obtuse angle and the edge 4 at an acute angle. The bezel section is how 12 shows, is curved over its radial width in such a way that the radially inner edge 3 has a greater axial distance than the radially outer edge 2 from a hub ring section 6 . The hub ring section 6 also has a radially outer edge 7 and a radially inner edge 8. Both edges 7, 8 are curved and connected to one another at their ends by edges 9, 10. The hub ring section 6 protrudes radially inwards beyond the cover ring section 1 . Seen in an axial plan view, the outer edge 7 of the hub ring section 6 is congruent with the outer edge 2 of the cover ring section 1. In other embodiments of fan wheels according to the invention, in particular diagonal or axial fan wheels, the outer edge 7 of the hub ring section 6 can also be offset and/or or at an angle to the outer edge 2 of the cover ring section 1. The edges 9, 10, seen in an axial top view of the segment, are congruent with the edges 4, 5 of the cover ring section 1 over part of their length. This property enables a particularly simple joining process. In other embodiments according to the invention, such a congruent configuration of the edges 9, 10 is not possible, for example if the wing is strongly sickled or twisted.

A wing 11 extends between the cover ring section 1 and the hub ring section 6, which in the exemplary embodiment is curved over its length and has the profile of a hydrofoil in cross section. The vane 11 is connected to the cover ring section 1 with its cover ring-side end 91 and connected to the hub ring 6 with its hub ring-side end 96 . The downstream end 12 of the Wing 11 runs out at an acute angle, while the inflow-side end 13, seen in plan view, is rounded in an arc ( 2 ).

The wing 11 extends with its outflow end 12 close to the edge 5 of the cover ring section 1. With its inflow end 13, the wing 11 protrudes, seen in an axial top view, over the cover ring section 1 and ends at a small distance from the edge 9 of the over the area of the hub ring section 6 protruding from the cover ring section 1.

Deviating from the exemplary embodiment shown, the wing 11 can also have a different cross-sectional configuration and/or a different extension. The wing 11 can not only be curved over its length, but also be designed to be wound over its length.

The hub ring section 6 has at least one passage opening 14 near its inner edge 8 . It is advantageously approximately half the width of the protruding hub ring section 6 and is used for the passage of fastening screws with which the fan wheel can be fastened to a hub of a drive motor in the installed position.

The hub ring section 6 can be flat. However, it is also possible, for example from 12 shows that the hub ring section 6 is angled or bent at the outer end. In other embodiments according to the invention, in particular diagonal gears, the hub ring section 6 can also run conically or curved over its entire or part of its extent.

When assembled to form an impeller ( figure 1 ) are of adjacent segments, the edges 4 and 5 of the respective cover ring sections and the edges 9 and 10 of the respective hub ring sections together. Regarding the entire impeller form Pairs of contiguous edges 4 and 5 joining areas 15 (on the cover side) and pairs of contiguous edges 9 and 10 joining areas 16 (on the hub side). In order to ensure that edges 4 and 5 and 9 and 10 lie together without gaps to form joining areas 15 or 16, the curvatures of edges 4 and 5 and edges 9 and 10 of the respective adjacent segments must be essentially identical. The joining areas 15 and 16 extend transversely to the circumferential direction. In the exemplary embodiment of a radial fan wheel shown, the joining areas 15 and 16 also extend transversely to the axis of the fan wheel. Since the wing 11 ends at a distance from these joining areas 15, 16, no additional burrs, edges and the like are produced on the wing 11 as a result of the manufacture from segments. When the fan wheel is assembled, the cover ring sections 1 of segments I to VII form the entire cover ring 1*, and accordingly the hub ring sections 6 of segments I to VII together form the hub ring 6*.

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

17 shows one of the segments of the in 16 Axialventilatorrades shown, in which all segments I to VII are of the same design, so that they can be produced in the same injection mold.

This in 17 The segment I shown 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 an edge 3 running parallel thereto and offset axially upstream. Both ends of the edges 2,3 are connected to each other by edges 4,5. The hub ring section 6 also has a downstream edge 7 and an upstream edge 8. Both edges 7, 8 are curved and connected to one another at their ends by edges 9, 10. The hub ring section 6 lies radially completely within the cover ring section 1. The axial extent of the hub ring 6* and cover ring 1* is identical in the embodiment shown, but can also be different in other embodiments of axial fan wheels, depending on the blade geometry.

Seen in the radial direction between the cover ring 1* and the hub ring 6* in the exemplary embodiment figure 16 an intermediate ring 71* is also present. Such an intermediate ring helps to achieve even greater strength of the assembled fan wheel. In an advantageous design, an intermediate ring can also be used to achieve advantages in terms of air performance, efficiency and the acoustics of the fan. One or more intermediate rings 71* can be present in all types of fan wheels, such as radial fans, diagonal fans or inlet or outlet guide wheels. Due to the production method from segments, the realization of intermediate rings is possible with less effort in terms of tool design than with production in complete casting.

This in figure 17 The segment I shown accordingly has an intermediate ring section 71 which has a curved edge 72 lying downstream with respect to the main flow direction of the axial fan and an edge 73 running parallel thereto and offset axially upstream. Both ends of the rims 72,73 are connected to each other by rims 74,75.

The edges 74, 75 of the intermediate ring sections 71 of the respective segments form joining areas 85 ( 16 ), which extend transversely to the circumferential direction of the fan wheel and with which adjacent segments I to VII abut one another. Since the wing 11 ends at a distance from these joining areas 85, no additional ones arise on the wing 11 as a result of the intermediate ring 71* Burrs, edges and the like. The intermediate ring sections 71 of segments I to VII form the entire intermediate ring 71* when the fan wheel is assembled.

Between the cover ring section 1 and the hub ring section 6, a wing 11 extends, which in the embodiment of figure 16 with segments according to figure 17 is curved and twisted along its length and has the profile of an airfoil in cross-section. The end 12 of the wing 11 on the outflow side runs out at an acute angle, as in the previous embodiment, while the end 13 on the inflow side, seen in cross section through the wing 11, is rounded in an arc, as in the exemplary embodiment according to FIG 2 is shown.

The wing 11 of the segmented embodiment according to FIG 17 extends with its downstream end 12 close to the edge 2 of the cover ring section 1. With its upstream end 13 the vane 11 extends close to the edge 3 of the cover ring section 1.

Deviating from the exemplary embodiment shown, the wing 11 can also have a different cross-sectional configuration and/or a different extension.

The hub ring section 6 has the impeller segment I according to 17 no device that serves to attach the impeller to an engine. The fan wheel formed from such segments 16 can be attached to an engine by pressing, clamping, gluing, welding or the like. Of course, in other embodiments of axial fan wheel segments, holes or the like can be provided, which serve to later attach the fan wheel to a motor.

The hub ring section 6, the cover ring section 1 and the intermediate ring section 71 can be cylindrical, particularly in the case of an axial fan wheel. However, it is also possible, similar to the exemplary embodiment according to FIG 20 shown by means of the cover ring 1* that the hub ring section 6 and/or the cover ring section 1 and/or the intermediate ring section 71 follows a more complicated, three-dimensional contour which can be better adapted in particular to the flow conditions.

In figure 23 an axial fan wheel according to the invention is shown, which consists of segments according to figure 24 is made. In this embodiment with hub ring 6*, cover ring 1* and intermediate ring 71*, wings 111 extend between cover ring 1* and intermediate ring 71*, which differ in shape and/or position and/or number of wings 112, which differ between intermediate ring 71 * and hub ring 6* extend. 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. In the case of embodiments with a plurality of intermediate rings 71*, even more variability can be brought into the design of the wings.

This in 24 shown segment of the axial fan according to 23 has the top ring portion 1, the intermediate ring portion 71 and the hub ring portion 6, from which the top ring 1*, the intermediate ring 71* and the hub ring 6* are manufactured. This segment has two wings 111 connecting the cover ring section 1 to the intermediate ring section 71 and one wing 112 connecting the intermediate ring section 71 to the hub ring section 6 .

The embodiment of an axial fan wheel, which 18 is shown in perspective, is an axial fan wheel without a cover ring and without an intermediate ring and is also composed of the identical segments I to VII, of which in 19 the segment I is shown. The construction from segments is similar to the construction according to the embodiment already described 16 . However This axial fan wheel does not have a cover ring, as is often the case with axial fans, in order to save weight and reduce the flow resistance. For this reason, only the joining areas 16 on the hub ring 6* remain as joining areas, which have to absorb a higher load in this embodiment. The segment I has the hub ring section 6 and the wing 11.

The embodiment according to 20 with the segments according to 21 is a fan wheel (stator) that is in operation. Stators can be vanes or vanes in a fan. With regard to the construction from 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 oscillations and vibrations of the fan during operation. The stator according to 20 is composed of 11 identical segments I to XI according to 21 constructed in the manner of 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 also provided with a flat flange 61* on the outflow side, which is formed by flange sections 61 of segments I to XI and to which the fan motor can later be attached. Holes are not yet provided in the segments, since in the exemplary embodiment a stator is made up of 11 segments, which would mean too many holes. The holes can be drilled in the flange 61* after assembly in this embodiment.

In particular with a large number of wings 11, 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, the injection molding tool for producing a segment then becomes more complicated. In addition, the number of wings 11, if you only want to have identical segments, by the number of Be divisible wings per segment.

It is sometimes advantageous, depending on the expected loads during operation, to have further intermediate rings 71* in the circumferential direction in addition to the cover ring and hub ring 1*, 6* in fan wheels according to the invention. One or more such additional rings can be located in the area between cover ring 1* and hub ring 6*. Their design with edges in the segments and joint areas in the assembled wheel is equivalent to the design of the cover ring and hub ring 1*, 6* according to the exemplary embodiments described. Intermediate rings 71* can provide additional stability, but can also have a positive effect on the flow (efficiency, acoustics). Such additional intermediate rings 71* can be realized from segments with comparatively little effort due to the manufacturing principle.

To produce an advantageous embodiment of a fan wheel according to the invention, segments I to VII are initially arranged in a star shape ( 15 ) and then pushed together roughly radially inwards until the edges 4 and 5, 9 and 10, 74 and 75 of segments I to VII are in contact with one another. At the resulting joining areas 15, 16, 85, the segments I to VII are firmly connected to one another in the manner described, for example glued or welded. High pressure is advantageously exerted on segments I to VII or on joining areas 15, 16, 85 during the gluing or welding process, so that segments I to VII lying against one another are firmly connected to one another. Fan wheels with more than seven segments are manufactured in a similar way. The segments can be produced in simple injection molding tools, so that the production costs can be kept low. The known materials customary for the injection molding of fan wheels can be considered as the material for segments I to VII. 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. Polyamide, polypropylene or polyester are preferably used as materials for the segments.

Glass, carbon, aramid, thermoplastic (PET, PA) or natural fibers such as flax, hemp, sisal, jute or coconut can be considered as reinforcing fibers for these materials.

In embodiments in which adjacent segments are connected by means of laser welding, the plastic used must be highly transparent for the laser light used. To achieve this, a plastic that 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. Furthermore, special reinforcing fibers (in particular glass fibers) are advantageously used which have little or no light refraction at the transition from polymer to reinforcing fiber.

This is possible through 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 result when the reinforcing fibers produced by injection molding segments I to VII have lengths of around 50 μm to over 15 mm. A preferred range is between about 200 µm and 10 mm.

If the segments I to VII are glued together at the joining areas 15, 16, 85, 1- or 2-component adhesives can be used for this purpose, such as polyurethane, acrylic, methacrylate or silicone. Solvent systems can also be used for bonding.

If the segments I to VII are laser-welded to one another at the joining areas 15, 16, 85, then diode lasers, CO2 lasers or NdYAG lasers can advantageously be used for this purpose.

The connection of the segments I to VII at the joining areas 15, 16, 85 can also be produced by friction welding, vibration welding or ultrasonic welding.

The connection of the segments I to VII at the joining areas 15, 16, 85 can also be carried out by means of induction welding or hot gas welding. Air, nitrogen or CO2, for example, can be considered as the hot gas.

In both cases, the plastic is softened in the area of the joining areas 15, 16, 85. Under the pressure under which the segments I to VII are pressed against one another at the joining areas 15, 16, 85, this results in a cohesive connection between adjacent segments, which leads to a secure connection of the segments after the joining areas have cooled.

Since the blade 11 and the ring sections 1, 6, 71 are formed in one piece with each other and form the segment, the fan wheel can be manufactured easily, quickly and inexpensively.

The fan wheel according to 3 is designed similarly to the fan wheel according to FIG 1 and consists of segments I to VII. The blades 11 of the fan wheel are in turn arranged in such a way that the joining areas 15, 16 run at a distance from the blades 11. This prevents the formation of burrs, edges or the like on the wings 11, so that complex reworking can be omitted. While in the embodiment according to Figures 1 and 2 segments I to VII are connected to one another exclusively by a material connection or by an adhesive connection with regard to loads that act in the circumferential direction, segments I to VII are in the exemplary embodiment according to FIG 3 additionally also connected to each other in a form-fitting manner with regard to such loads. This form fit is provided in the area of the edges 4, 5 of the cover ring sections 1 and the edges 9, 10 of the hub ring sections 6 of segments I to VII. The radially inwards Areas of the hub ring sections 6 protruding beyond the cover ring sections 1 are of the same design as in the embodiment according to FIG Fig.1 . The form fit between adjacent segments I to VII is designed in such a way that the segments cannot be separated from one another in the circumferential direction. In the non-adhered or non-welded state, the segments can only be detached from one another by displacing adjacent segments in relation to one another in the axial direction of the fan wheel.

On the edge 5 of the cover ring section 1 as well as on the region of the edge 10 of the hub ring section 6 lying underneath it, viewed in the axial direction, there is an opening 17 with an approximately mushroom-shaped outline. The opposite edge 4 of the cover ring section 1 and the area of the edge 9 of the hub ring section 6 lying underneath it, seen in the axial direction, are provided with a protruding mushroom-shaped projection 18 which engages in the opening 17 of the adjacent segment. The openings 17 and the projections 18 are designed to be complementary to one another, so that their edges lie against one another. Due to the mushroom-shaped design, the openings 17 and also the projections 18, seen in the circumferential direction, are each provided with an undercut. Deviating from the mushroom-shaped design, the positive connections can also have other outline shapes. You only have to be designed in such a way that the adjacent segments I to VII cannot be separated from one another in the circumferential direction of the fan wheel.

The openings 17 and the projections 18 are provided on the cover ring sections 1 and the hub ring sections 6, respectively. They can also be provided only on the cover ring sections or only on the hub ring sections, depending on where high loads are to be expected on the respective fan wheel. There can also be several on an edge 4, 9 or 5, 10 along its length Perforations 17 and complementary projections 18 may be provided. The wings 11 are arranged on segments I to VII in such a way that they are at a distance from the openings 17 and the projections 18 .

According to the invention, a projection 18 is a protruding form-fit part and an opening 17 is an at least approximately complementary depression on an edge 4, 9, 74 or 5, 10, 75.

In this embodiment too, the one-piece segments I to VII are identical to one another, so that only a single injection molding tool is required for the segments. The positive-locking elements 17, 18 offer additional guidance when segments I to VII are joined together and also ensure additional dimensional stability when the fan impeller is subjected to loads in the circumferential direction. Due to the form-fitting elements 17, 18, the segments I to VII are not joined together in a star shape to form the fan wheel, but rather in the axial direction.

The adjacent segments I to VII are not only connected in a form-fitting manner at the joining areas 15, 16, but also via an adhesive connection, a welded connection or the like, as has been described with reference to the previous embodiment. During the gluing or welding process, the adjacent segments I to VII are advantageously pressed firmly against one another, so that the connection at the joining areas 15, 16 is optimal. In the area of the form-fitting connection 17, 18, too, adjacent segments can be firmly connected to one another via the adhesive or welded connection. In other embodiments according to the invention, positive-locking connections in the circumferential direction can be carried out in an equivalent manner to the embodiment described 3 can also be implemented with axial fans, diagonal fans or stators. Such positive locking can also be implemented in the case of the intermediate ring sections 71 will. In these cases, too, there are restrictions with regard to the joining process, ie the segments cannot be brought together in the circumferential direction relative to one another.

The fan wheel according to 4 in the example also has the one-piece segments I to VII. They are in turn of the same design, so that they can be manufactured with just one injection molding tool. Similar to the embodiment according to 1 the segments I to VII are designed in such a way that they can be arranged in a star shape and then pushed together, similar to what is shown in 15 is shown.

Segments I to VII are designed in such a way that, in addition to the joining areas 15, 16 on the cover ring 1* and the hub ring 6*, further joining areas 86 ( 4 ) arise in the area of the wings 11. This has the advantage that the adhesive or welding area for joining adjacent segments is increased compared to the previous embodiments. The segments I to VII are designed in such a way that complete wings 11 are formed only by assembling adjacent segments.

figure 5 12 shows one of these segments in a bottom view from the side of the hub ring section 6. FIG. It has the curved outer edge 7 and the curved inner edge 8. The edge 10 connecting one end of the edges 7, 8 is curved, viewed in the axial direction. The opposite edge 9, which connects the other ends of the two edges 7, 8, is also curved over its length, seen in the axial direction of the fan wheel, with a largely identical curvature as edge 10, so that adjacent, identical segments can be joined together without a gap. A wing part 11a, 11b extends in direct connection with the two edges 9, 10 in each case. The wing parts 11a, 11b extend between the hub ring portion 6 and the (in figure 5 completely covered by the hub ring section 6) cover ring section 1.

If adjacent segments I to VII are placed together with their edges 4, 5, 9, 10, the wing parts 11a, 11b lie against each other with their edges 19, 20 and in this way form the wing 11, which in this case is hollow. The edges 19 and 20 of adjacent segments lying against one another when the impeller is assembled form an additional joining area 86. The vane 11 is otherwise of the same design as in the embodiments according to FIGS 1 or 3 . The vane 11 is also arranged in the same way as in these exemplary embodiments in relation to the cover ring 1* and the hub ring 6* of the fan wheel.

If adjacent segments I to VII are connected to one another by an adhesive connection, then the adhesive is not only provided in the joining areas 15, 16 of the rings, but also in the joining area 86 of the wings 11. This results in a very large adhesive surface, which ensures a firm and connection between adjacent segments I to VII that can withstand high loads. If adjacent segments to VII are connected to one another by a welded connection, the welding area around the area of the joining area 86 of the wings 11 is enlarged in this embodiment, which leads to an increased load-bearing capacity.

Since the wings 11 are hollow, the fan wheel has a relatively low weight. In addition, the hollow vanes 11 have the advantage that they can be used to design channels for targeted secondary flows in a simple manner in terms of flow technology.

After the joining process, edges, burrs or the like can be present in the area of the joining areas 86 of the wings 11, but these can easily be removed in a conventional manner. The segments I to VII are identical to each other and have a center line 21 in the axial top view, the curvature of which is identical to the curvature of the edges 9, 10 in an axial top view. The width of the segment measured 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 has the greatest circumferential width in the area of the outer edge 2, 7 and the smallest circumferential width in the area of the inner edge 8.

Due to the design described, the segments I to VII, as shown by 15 is shown schematically, push together in a star shape and press against each other in the circumferential direction, so that the segments I to VII at the joint areas 15, 16, 86 lie firmly against one another. The tracks on which the segments are brought together in a rotationally symmetrical manner during the joining process must be carefully selected depending on the course of the joining areas 15, 16, 86 in order to avoid undesirable collisions. In particular, curved paths are necessary in some embodiments.

There figure 5 shows the segment viewed from below, only the inner edge 3 of the cover ring section 1 can be seen. The other edges 2, 4, 5 of the cover ring section 1, seen in plan view of the segment, are congruent over their length to the edges 7, 9, 10 of the hub ring section 6.

Fig.6 shows, in plan view of the hub ring section 6, a segment which is designed similarly to the segment according to FIG 2 . The blade 11 is provided on the segment in such a way that its two outflow and inflow ends 12, 13 are at a distance from the edges 4, 5, 9, 10. The wing 11 protrudes as in the embodiment 2 radially slightly above the inner edge 3 of the cover ring section 1.

In contrast to the embodiment according to 2 the wing 11 is hollow. The wing 11 is not continuously hollow. The cavity ends in the area of the cover ring section 1, so that this is not broken through by the cavity.

The hollow formation of the wing 11 is achieved in the injection mold with the help of a core slide. Because of this core slide, the wing 11 is open in the area of the hub ring section 6 . In order to avoid noise and dirt deposits inside the blade 11 when the fan wheel is in use, the blade 11 is advantageously closed with a cover or the like after injection molding or after the assembly process of the entire fan wheel, or is filled with a material, for example with foamed material. The cover can be glued, welded or attached to the hub ring section 6 in some other suitable manner. This closure piece is advantageously designed in such a way that its outside lies flush with the outside of the hub ring section 1 . In order to achieve this, a depression must be provided on the injection-molded part in the region of the cavity on the hub ring section 6, into which the closure piece can be introduced flush with the surface.

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

In the injection molding tool, two core slides are provided to produce the web-shaped reinforcement 22, which are located next to one another at a small distance, so that when the plastic is injected, the web 22 is formed between the core slides.

In the embodiments according to 1 , 3 and 4 are the joining areas 15, 16 between the segments I to VII not on a radial, seen in the axial direction of the fan wheel. Based on a Radial 60 ( 1 , 3 and 4 ), which runs through the intersection between the respective dividing line 15, 16 and the inner circular edge 8 of the fan wheel, the joining areas 15, 16 are at an angle α to this radial 60. Depending on the course of the dividing lines 15, 16, the angle α increases in the direction from the inner edge 8 to the outer edge 2 too.

The segments I to VII can also be designed in such a way that the joining areas 15, 16 lie on the radial line 60, so that the angle α is 0°.

The angle α can be up to about 80°, depending on the design of segments I to VII. This angular range is independent of the way in which segments I to VII are connected to one another.

25 shows a non-inventive embodiment of cross sections through joining areas 15, 16, 85, with which no effect of enlarging the joining area is achieved. It shows, by way of example and in an enlarged representation, a section AA through a joining area 15, 16, 85 with adjoining segment edges 4, 9, 74 and 5, 10, 75 (see 1 , 3 , 16 , 18 , 20 ). The profile of the joining region 15, 16, 85 is essentially that of a straight line on average, which connects the inside 30 with the outside 31 of the ring sections 1, 6, 71 by the shortest possible route. The joining area 15, 16, 85 or the edges 4, 9, 74 and 5, 10, 75 of segments I and II run approximately perpendicular to the inside 30 and to the outside 31. This design is the simplest design for a cross section of a joining area . The associated tool design for the injection molding tool is simple and inexpensive. A joining area designed in this way also makes it possible for the segments I and II to be joined to one another in a direction transverse to the ring sections 1, 6, 71, as is the case, for example, for the embodiment according to FIG figure 3 necessary is. However, in this embodiment, the joining area 15, 16, 85 has a rather small area for gluing or welding, and there is none additional positive locking in the axial or radial direction between the segments. Also, no additional guidance is achieved during the joining process.

Based on Figures 8 to 11 , 14 and 26 possible configurations of cross sections through joining areas 15, 16, 85 are described as examples, with which the joining area can be significantly increased without increasing the wall thicknesses of the rings 1*, 6*, 71*, and with which an at least partial form fit between adjacent segments I to VII can be produced with regard to displacements in the axial and/or radial direction (designs that increase the size of the joint surfaces). the Figures 8-10 and 14 show embodiments of the invention. These figures each show, as an example and in an enlarged representation, a section AA through a joining region 15, 16, 85 with adjacent segment edges 4, 9, 74 and 5, 10, 75 (see 1 , 3 , 16 , 18 , 20 ). In these examples, the joining surfaces are designed to increase the size, which not only leads to an increase in the adhesive/weld surface, but also ensures increased dimensional stability of the segments that are joined together. In addition, this special design of the joining areas 15, 16, 85 when assembling the segments I to VII to form the fan wheel also results in a guide that facilitates the assembly of the segments to form the fan wheel. As a result, the manufacturing process of fan wheels according to the invention can be made considerably more economical, faster and more precise.

In an exemplary embodiment according to FIG 8 For example, an edge 4,9,74 of segment I has a protruding tongue 25 which extends at least partially the length (perpendicular to the plane of the drawing) of edge 4,9,74. An edge 4, 9, 74 can also have a plurality of springs 25 distributed over its length. The spring 25 tapers towards its free end and is approximately half the thickness of the ring section 1, 6, 71.

An opposite edge 5, 10, 75 of a segment II is at least provided with a corresponding groove 26, in which the spring 25 of the respective adjacent segment engages. The groove 26 is complementary to the respective tongue 25 and is also approximately half the thickness of the ring section 1 , 6 , 71 . The joint area 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. An adhesive is introduced in the joining region 15, 16, 85 between the edges 4, 9, 74 and the edges 5, 10, 75.

According to the invention, a tongue 25 is a protruding form-fit part and a groove 26 is an at least approximately complementary depression on an edge 4, 9, 74 or 5, 10, 75.

The tongue 25 and the groove 26 are formed in such a way that the ring sections 1, 6, 71 of the segments I, II abut one another, so that no gap is formed on the outside and inside of the joined rings 1*, 6*, 71* .

For the sake of completeness, it should be mentioned that an interchange of the features "groove" and "tongue" with regard to the edges 4, 9, 74 and 5, 10, 75 is equally within the meaning of the invention, which also applies to the embodiments according to FIGS Figures 9 to 11 , 14 and 26 is applicable.

In the embodiment according to 9 the tongue 25 is formed in such a way that it has a small distance from the side walls and from the bottom of the groove 26. As a result, a free space 27 is formed in the joining region 15, 16, 85, into which a viscous adhesive 28 can be introduced. In this exemplary embodiment, the joining region 15, 16, 85 has a rather voluminous shape due to the free space 27 that is completely or partially filled with adhesive 28. This adhesive can be introduced into the groove 26 before the two segments I, II are joined. Structurally, the size of the free space 27 after merging has taken place of segments I and II is present, is ensured by a stop 98, i.e. segments I and II are moved towards one another until at least in the area of stop 98 there is direct contact between segment edges 4, 9, 74 and 5, 10, 75 is made. Alternatively, it is possible to introduce the adhesive into the free space 27 perpendicular to the plane of the drawing after the two segments I and II have been joined.

In both embodiments described according to the Figures 8 and 9 the adhesive is advantageously also applied to the areas of the stop 98, so that the segments I, II lying against one another are firmly connected to one another over a large area by the corresponding adhesive.

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

In the example 11 the edges 4, 9, 74 and 5, 10, 75 of the segments I, II are stepped. Viewed in section, each segment edge 4, 9, 74 and 5, 10, 75 consists of a protruding form-fitting part 25* and a depression 26* complementary to the protruding form-fitting part 25* of the adjacent segment. The gradations of the two edges 4, 9, 74 and 5, 10, 75 are designed to be complementary to one another, so that the segments I, II lie flat against one another at the joining area 15, 16, 85.

The joining area 15 , 16 , 85 has, seen in section, an end face area 32 , 33 adjoining the inside 30 and the outside 31 of the ring sections 1 , 6 , 71 perpendicularly, which are connected to one another by a wall area 34 . It advantageously runs at a slight angle with respect to the inside 30 and the outside 31 of segments I, II. The sloping wall area 34 facilitates the joining of the adjacent segments I, II. The transitions between the end face areas 32, 33 and the wall area 34 is rounded in order to avoid cracking. An adhesive is applied to the end face areas 32, 33 and the wall area 34, so that the two segments I, II are reliably bonded to one another over a large area at the joining area 15, 16, 85. The stepped design of the joining areas 15, 16, 85 is advantageously provided over their entire length.

The stepped design of the joining areas 15, 16, 85 also enables a simple and problem-free joining process when manufacturing the fan wheel.

In the example 26 the effect of enlarging the joining surfaces is achieved in that the joining region 15, 16, 85, seen in cross section, forms acute angles β or β* with the inside 30 or the outside 31 of the ring sections 1, 6, 71, which are significantly smaller than 90°, advantageously between 70° and 30°. If the joining region 15, 16, 85 runs straight, viewed in cross section, β and β* have approximately the same amount. However, the joining area 15, 16, 85 can also be curved when viewed in section, as a result of which the amounts of the two angles β and β* can also differ significantly from one another.

The cross-sectional training in particular according to Figures 8, 11 , 25 and 26 are also excellently suited for embodiments in which the segments I, II are connected to one another by a planar weld will. Based on 14 is an advantageous embodiment of the tongue and groove connection similar to that 8 explains in detail how it is particularly well suited 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 can range from about 3 mm 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 ranging from 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 has a self-centering effect during the joining process. In addition, this cross-sectional tapering 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 tongue 25 rests with its side walls flat against the side walls of the groove 26 . The end face 35 of the tongue 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 in such a way that the flanks 39 and 40 of the tongue 25 lie flat against the groove and that on the Inside 30 and the outside 31 of the rings 1*, 6*, 71* no gaps arise.

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

In the cross-sectional area d1, on the other hand, the tongue 25 is very heavily loaded, so that the area 37, 38 surrounding the groove of 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 on segment I with the radius R1. This radius R1 is advantageously about (0.05 to 0.3) • D. The same value or a slightly larger value can be selected for the complementary radius R1 on segment II in order to prevent a premature collision of segments I and II in the range from R1 to be safely avoided during the joining process. This would result in a very small (in 14 not shown) gap arise.

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

The transition from the side walls of the groove 26 to the bottom side 36 of the groove 26 is rounded off with the radius R2. It is advantageously (0.05 to 0.3)•D. So that the power flow can be optimally guaranteed, the rounding in the transition area is bionic in a particularly advantageous manner, ie no constant radius is provided. As a result, this rounded transition can be optimally adapted to the loads occurring when the fan wheel is used in such a way that crack formation is avoided in any case. Advantageously the curvature of the transition is designed in such a way that the radius of curvature at the bottom 36 of the groove is small and gradually increases in the direction of the flanks 39, 40.

In the fully assembled state, i.e. when the segments I and II abut one another at the stop 98, there is already a prestress in the area of the flanks 39, 40, advantageously due to the compression of the segments I and II in the joining process. This ensures that the flanks 39, 40 of the tongue 25 and the corresponding flanks of the groove 26 lie against one another without play after assembly.

If the segments I, II are connected to one another by laser welding in the joining area 15, 16, 85, then in an advantageous embodiment a laser-absorbing liquid is applied to the edges 4, 9, 74 and/or 5, 10, 75 before the joining process. After assembly, the laser light, which penetrates the specially used material of ring sections 1, 6, 71 that is transparent to the laser light used, is converted into heat in this area during the welding process, causing adjacent material to melt and bond. Since the absorbing liquid absorbs only part of the laser light or becomes laser-transparent as a result of the welding process itself, welding can be carried out simultaneously in the area of both flanks 39 and 40 of the spring 25 using a single laser light source.

If welding is carried out simultaneously in the region of both flanks 39 and 40 of the spring 25 using a single laser light source, it can be advantageous if a liquid which absorbs the laser light to different extents is applied to the two flanks 39 and 40 in each case. A liquid that absorbs the laser light to a lesser extent is then applied to the flank 39 near the laser light source, while a liquid that absorbs the laser light more strongly is applied to the flank 40 that is further away from the laser light source. In this way, with respect to the flanks 39, 40 more uniform welding process can be set.

If such a welding process is carried out, a special plastic that is largely transparent for lasers used in welding is advantageously used as the material for segments I to VII. In an advantageous embodiment, the segments I-VII are not machined, particularly in the area of their edges 4, 9, 74 and 5, 10, 75 and their immediate surroundings after the injection molding process, since the surfaces otherwise absorb, reflect and/or absorb laser light to a high degree. or have laser light scattering properties. A special liquid that absorbs laser light is applied to the points to be welded, essentially the edges 4, 9, 74 and/or 5, 10, 75, in the manner described before the welding process. It ensures that the energy of the laser light is converted into heat at exactly the desired point, so that the plastic melts locally in this area. This laser technology makes it possible to weld not only on the outer surface of the ring 1*, 6*, 71* in the area of the inside 30 and the outside 31, but also in the inner areas of the joining areas 15, 16, 85 of the material of the fan wheel to perform.

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

Based on Figure 27a an advantageous embodiment of the tongue and groove connection between adjacent segments I, II is explained, which is similar to the embodiment according to FIG 14 . The embodiment according to Figure 27a is particularly well suited for laser welded connections between the two segments I, II. Segment I has the spring 25 as a form-fitting part, the flank 39 of which facing the upper side 30 of the ring section 1, 6, 71 is firmly welded to the side wall of the groove 26 in the ring section 1, 6, 71 of segment II. This design is advantageous when welding on the flank 40 of the spring 25 remote from the laser light source is not possible or only possible with difficulty, for example due to insufficient laser light transparency of the plastic used. The result of this is that on the flank 40 no or only a weakly load-bearing welded connection can be achieved by laser welding. A large part or even the entire power transmission therefore takes place via the flank 39 .

For this reason, the flank 39 is equipped with a larger area than the opposite flank 40. This has the consequence that the spring 25, in contrast to the exemplary embodiments according to FIG Figures 8 to 10 and 14 has not symmetrical but asymmetrical cross-section. This leads to an asymmetrical transmission of force between the two segments I and II. The asymmetrical cross-sectional design of the spring 25 means that the areas 37, 38 of the ring section 1, 6, 71 of the segment II lying on both sides of the spring 25 are asymmetrically designed, in section according to Figure 27a seen. A large part or the entire power transmission takes place via the area 37 belonging to the larger flank 39 . For this reason, this area 37 has a significantly greater thickness than the opposite area 38, which is also significantly shorter than the area 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 when they are assembled to form the fan wheel. Due to the wedge angle between the two flanks 39, 40, the contact pressure required for laser welding is achieved in the region of the flank 39 when they are joined together. For the rest, also apply to this embodiment with regard to the exemplary embodiment according to FIG 14 statements made.

The flank 39 adjoins the stop 98 at an obtuse angle, while the flank 40 adjoins the stop 98' of the segment I or its edge section 1, 6, 71 approximately at right angles. Due to the asymmetrical cross-sectional design of the spring 25, the two stops 98, 98' are offset from one another transversely to the thickness direction of the segments I, II, as shown in FIG Figure 27a emerges. When they are brought together, segments I and II are moved towards one another until they come into contact with one another in the area of stops 98, 98'. An adhesive can be provided in the area of the stops 98, 98', 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' each connect at right angles to the upper side 30 and the lower side 31 of segment I. The groove 26 as a recess in the segment II is designed to be approximately complementary to the tongue 25, so that the segments I, II that are plugged together can be reliably and firmly connected to one another. This also ensures perfect power transmission.

The stops 98, 98' of segment I form the joining area 15, 16, 85 with the corresponding counter-stops of segment II.

Figure 27b shows a similar design of the tongue and groove connection as Figure 27a . This connection is also particularly well suited in particular for laser welded connections. In order to increase the area of the flank 39 of the spring 25 that primarily transmits the force and the area 37 that primarily transmits the force, the wall thickness in the area of the joining area 15, 16, 85 is greater than in the area outside of this joining area. For this purpose, the underside 31 of the ring section 1, 6, 71 of the segment I is designed to run in a bent manner, while the upper side 30 runs flat.

In the same way, the underside 31 of the ring section 1, 6, 71 of the segment II is bent in the joining area, as a result of which the wall thickness in the joining area increases. In the area outside the joining area the segments I, II have the wall thickness D. Within the joining area, the wall thickness D _max of the segments I, II is greater than the wall thickness D in the area outside the joining area. The wall thickness D _max is advantageously in the range of 1.05 to 1.2 times the wall thickness D.

The area 38 of segment II, which is only used for centering and for applying the contact pressure during the joining process, protrudes beyond the rest of the underside 31 .

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

For the rest, this embodiment is designed in the same way as the exemplary embodiment according to FIG. Figure 27a . This also applies to the embodiment according to FIG Figure 27b the explanations regarding the exemplary embodiments according to the 14 and 27a .

12 shows a perspective view of a further embodiment of a segment for producing the fan wheel. Out of 12 shows the basic structure of the previously described segments. The one-piece segment has the wing 11 extending between the bezel portion 1 and the hub ring portion 6 . The bezel portion 1 has the curved outer edge 2 and the curved inner edge 3 seen in plan. In this exemplary embodiment, the outer edge 2 is provided with a bend 41 which extends over the circumferential length of the cover ring section 1.

The cover ring section 1 is curved upwards at a distance from the bend 41 in such a way 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 rim 7 and the inner curved rim 8. The rims 7, 8 are connected to each other by the rims 9, 10 at both ends thereof. In the area of the outer edge 7 the hub ring section 6 is angled slightly opposite to the cover ring section 1 . Incidentally, the boss ring portion 6 is flat.

The edges 4, 9 are provided with the springs 25, as is based on the Figures 8 - 10 and 14 has already been described. The edges 5, 10 are provided with the grooves 26 accordingly. The tongues 25 are interrupted by recesses 42, the grooves 26 are also interrupted by areas 43 that are complementary to the recesses 42. The mutually complementary recesses and areas 42, 43 are designed in such a way that assembly is facilitated. In the assembled state, the recesses 42 and areas 43 achieve an additional form fit in the longitudinal direction of the joining area 15, 16. In addition, the recesses and areas 42, 43, due to their sloping shape, ensure that adjacent segments are correctly positioned relative to one another during the joining process (centering effect).

Seen in plan view of the segment, it has the same outline shape as the segment according to FIG 2 . Therefore, with regard to the arrangement of the edges of the cover ring section 1 and the hub ring section 6, reference can be made to the statements made there.

22 shows a section of a segment edge 4, 9, 74 in a lateral plan view and in an enlarged representation Figures 8 - 10 and 14 described can be designed. Along the edge 4, 9, 74 there are interruptions 44 at approximately constant intervals between the springs 25 present. In this case, the groove (not shown) of the neighboring segment can be designed to be continuous, ie without interruptions. The technical advantage that is achieved with these interruptions is that the flexibility of the springs 25 with regard to small displacements transverse to the ring sections 1, 6, 71 is greater, which is important during the joining process to compensate for tolerances in the direction transverse to the ring sections 1, 6, 71 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 between two adjacent springs 25 is advantageously provided, which can be a full rounding or also bionic, ie can be designed with a non-constant radius.

13 finally shows in axial section one half of a radial fan wheel. It is reinforced by three bands 54 to 56 running around its circumference. The strips are advantageously applied to the fan wheel under pretension. The pretension can be in a range between about 10 N and about 10 kN, preferably about 10 to 100 N/mm ₂ cross-sectional area of the strip.

In the exemplary embodiment, the fan wheel has three bands 54 to 56. Depending on the size of the fan wheel, only one, two or more than three bands can also be provided. The number of bands can be between 1 and 10. Thermoplastics are preferably used for belts 54 to 56, such as polyamide (PA6, PA66, PA66/6, PAPA, PPA, PA 4.6, PA12), polyester (PBT, PET), polypropylene (PP), PPS, PES, PESU, PEEK, ABS, PC, ASA and the like. A polyamide, a polypropylene or a polyester is preferably used as the material for the tapes.

Duroplasts can also be used for the bands 54 to 56, such as epoxy resin, urea resin or phenolic resin. An epoxy or phenolic resin system is preferably used as the duroplast.

The bands 54 to 56 are advantageously reinforced with fibers, regardless of whether they are made of a thermoplastic or a thermoset. Glass, carbon, aramid, thermoplastic (PET, PA) or natural fibers such as flax, hemp, sisal, jute or coconut can be used as reinforcing fibers.

The fibers are preferably continuous fibers, which are easy to manufacture and inexpensive. They can be introduced into the plastic mass of the bands 54 to 56 without any problems.

The bands 54 to 56 extend over the circumference of the fan wheel and are attached to it in a suitable manner. Thus, the bands 54 to 56 can be connected to the fan wheel by welding. Diode lasers, but also other laser systems, can be used for the welding process. If the segments are made of largely laser-transparent material, in an advantageous embodiment a laser-absorbing liquid is applied in the area of the strips 54 to 56 to be welded on before the laser welding. Ultrasound can also be used for welding. It is also possible to produce a fixed connection between the bands and the fan wheel by friction in the circumferential direction.

As a further possibility for connecting the strips 54 to 56 to the fan wheel, adhesive methods can also be considered. 1-component or 2-component adhesives, such as polyurethane, acrylic, methacrylate or silicone, or solvent systems come into consideration as adhesives.

The connection between the bands 54 to 56 and the fan wheel can also take place in that they are wrapped with a hardening duroplast, which hardens after being wrapped around. This achieves a secure, firm connection between the respective band 54 to 56 and the fan wheel.

In the illustrated embodiment, the cover ring 1* is provided along its outer edge 2 with a circumferential groove 57 into which the band 55 is inserted. The groove 57 is thus present on the outside diameter of the cover ring 1*.

There is also a circumferential groove 58 on the inside diameter of the cover ring 1*, which groove 58 accommodates the band 54.

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

All grooves 57 to 59 are open in the circumferential direction of the fan wheel. As a result, the strips 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 VII. Each of these segments then has the corresponding annular groove sections in its cover ring section 1 or hub ring section 6, which form the annular grooves running around the circumference of the fan wheel when segments I to VII are joined together.

The groove side walls guide the bands 54 to 56 in the axial direction so that they cannot slip off the fan wheel.

The strips 54 to 56 can be wound several times around the circumference of the fan wheel. The strips 54 to 56 are advantageously wound over the circumference of the fan wheel so often that the grooves 57 to 59 are completely filled with the strip.

In principle, however, it is sufficient if the respective band 54 to 56 is wound only once over the circumference of the fan wheel, with the two ends of the band overlapping one another. The overlap is advantageously at least 10 bandwidths up to a maximum of 20% of the circumference. With such a configuration, it is advantageous if the respective band 54 to 56 has a width that corresponds to the width of the groove. The segments I to VII are held firmly together by the bands 54 to 56, so that even under high loads, for example at high speeds and large diameters of the fan wheel, there is no risk of the segments becoming detached from one another.

If the fan wheels are provided with the endless fiber-reinforced strips 54 to 56 described, the fan wheels can be operated at higher limiting speeds.

The bands can also be provided for fan wheels that are not made from segments as according to the invention, but are formed in one piece. In the case of such fan wheels, too, the strips 54 to 56 advantageously wound onto the fan wheel with pretension have an advantageous effect, in particular with regard to increasing the limit speed of the fan wheel.

The proportion of 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.

Axial impellers, diagonal impellers or stators can also be advantageously reinforced in the manner described with strips 54 to 56 on cover ring 1* and/or hub ring 6* and/or intermediate rings 76*.

In the case of fan wheels made from segments, the occurrence of weld lines, which inevitably occur when complete wheels are injection molded, can be completely avoided. The injection molding of individual segments, in particular in the case of segments with only one wing 11, can be designed without the occurrence of weld lines. This weak point, which is difficult to control, can thus be avoided with fan wheels assembled from segments. The strength of the joining areas 15, 16, 85, which is realized by adhesive or welded connections, can be achieved with the described elements of the invention will.

The segments are designed in such a way that they can be brought together in the same or similar movement during the assembly process. In 15 segments I to VII are shown in the left figure in their initial state. The motion arrows for each segment show that they perform the same merge motion. This greatly simplifies and facilitates the assembly process. However, this type of merging is only possible with segments that have edges 4, 9, 74; 5, 10, 75 do not have any protruding form-fitting elements that cause a form-fitting connection in the circumferential direction, as is the case in 3 is shown. In this case, the segments must be joined because of the projection 18 and the opening 17 in the axial direction. In this case the common direction of movement of the segments can be the axial movement.

The fan wheel can still be machined after the joining process. This is important, for example, when high concentricity is required in certain areas of the fan wheel. This is the case, for example, for grooves 57 to 59 ( 13 ) for bands 54 to 56. Post-processing is also necessary, for example with regard to the centering diameter and the outer diameter of the cover ring 1* or the hub ring 6*. The grooves 57 to 59 can also initially not be provided in the segments I to VII and can be machined after the segments have been joined.

Claims (17)

1. A fan wheel having blades (11) arranged in a distributed manner over the circumference, which are connected to one another in the circumferential direction by means of at least one ring (1*, 6*, 71*), the fan wheel consisting of at least three segments (I to VII), which are constructed in one piece and in each case have at least one ring section (1, 6, 71) of at least one ring (1*, 6*, 71*) and either one blade (11) or at least one section (11a, 11b) of blades (11) and are joined to form the fan wheel, in which at least the ring section/the ring sections (1, 6, 71) adjoin by way of edges (4, 9, 74 and 5, 10, 75) that lie transverse to the circumferential direction of the fan wheel and form joining regions (15, 16, 85), at least one edge (4, 9, 74 and 5, 10, 75) of a ring section (1, 6, 71) of each segment (I to VII) being provided with at least one projecting positive-fitting 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) is provided with at least one depression (26, 26*, 17) that is at least approximately complementary to the positive-fitting part (25, 25*, 18),
   characterized in that the positive-fitting part (25, 25*, 18) tapers in the direction of its free end, in that the transition at least of the one side surface (39, 40) of the positive-fitting part (25, 25*, 18) into the edge (4, 9, 74 and 5, 10, 75) of the ring section (1, 6, 71) takes place in a curved manner, and in that the edges (37, 38) delimiting the depression (26, 26*, 17) taper in the direction of the free end thereof.
2. The fan wheel according to Claim 1,
   characterized in that the depression is arranged as a groove (26) in the region between the upper side (30) and the underside (31) of the ring section (1, 6, 71).
3. The fan wheel according to Claim 1 or 2,
   characterized in that the depression (26, 26*, 17) has a depth (t) which lies in the range of approximately (0.7 to 2.5) D, wherein (D) is the wall thickness of the ring section (1, 6, 71).
4. The fan wheel according to one of Claims 1 to 3,
   characterized in that the transition at least of the one side surface (39, 40) of the positive-fitting part (25, 25*, 18) into the edge (4, 9, 74 and 5, 10, 75) of the ring section (1, 6, 71) takes place with a radius (R1) which is approximately 0.05 to 0.3 of the wall thickness (D) of the ring section (1, 6, 71).
5. The fan wheel according to one of Claims 1 to 4,
   characterized in that the regions (37, 38) between the side walls of a depression formed as a groove (26) and the upper side and underside (30, 31) of the ring section (1, 6, 71) are of approximately equal or different thickness.
6. The fan wheel according to one of Claims 1 to 5,
   characterized in that the one side surface (39, 40) of a positive-fitting part that is formed as a flute (25) is larger than the other side surface.
7. The fan wheel according to one of Claims 1 to 6,
   characterized in that the wall thickness (D_max) of the ring section (1, 6, 71) in the region of the depression (26, 26*, 17) is larger than the wall thickness (D) in the region outside of the depression.
8. The fan wheel according to one of Claims 1 to 7,
   characterized in that the fan wheel has at least one hub ring (6*), which connects the blades (11) to one another in the circumferential direction at the hub-ring-side ends (96) and at which the fan wheel is connected to a drive motor.
9. The fan wheel according to one of Claims 1 to 8,
   characterized in that the fan wheel has at least one end ring (1*), which connects the blades (11) to one another in the circumferential direction at the end-ring side ends (91) thereof, and in that the hub ring (6*) and the end ring (1*) are preferably arranged offset to one another and the blades (11) extend between hub ring (6*) and end ring (1*).
10. The fan wheel according to one of Claims 1 to 9,
    characterized in that the fan wheel has at least one intermediate ring (71*), which connects the blades (11) to one another in the circumferential direction and is fastened at the blades in the region between the lateral ends (96, 91) thereof, wherein the segments (I - VII) have at least one intermediate ring section (71) in each case.
11. The fan wheel according to one of Claims 1 to 10,
    characterized in that the segments (I to VII) are of at least approximately identical construction and are advantageously injection-moulded parts.
12. The fan wheel according to one of Claims 1 to 11,
    characterized in that the edges (4, 9, 74; 5, 10, 75) of the ring sections (1, 6, 71) adjoin essentially congruently and form joining regions (15, 16, 85), by way of which adjacent segments (I to VII) adjoin in a planar manner.
13. The fan wheel according to one of Claims 1 to 12,
    characterized in that adjacent segments (I to VII) are connected to one another by means of adhesive bonding and/or welding at the joining regions (15, 16, 85).
14. The fan wheel according to one of Claims 1 to 13,
    characterized in that the inflow-side and outflow-side ends (12, 13) of the blades (11) have spacing from the joining regions (15, 16).
15. The fan wheel according to one of Claims 1 to 14,
    characterized in that at least one reinforcing tape (54 to 56) is wound around the fan wheel on at least one ring (1*, 6*, 71*), which reinforcing tape can consist of thermoplastic or thermoset plastic and preferably contains reinforcing parts, preferably virtually endless reinforcing fibres.
16. The fan wheel according to Claim 15,
    characterized in that the reinforcing tape (54 to 56) is fastened on a ring (1*, 6*, 71*) of the fan wheel by welding or adhesive bonding.
17. The fan wheel according to Claim 15 or 16,
    characterized in that at least one ring (1*, 6*, 71*) of the fan wheel is provided with at least one circumferential groove (57 to 59) for accommodating the reinforcing tape (54 to 56).

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