EP0310121A2 - Production method of pumping and/or guiding means for fluid machines and radial impeller manufactured thereby, in particular coolant impeller for combustion engines - Google Patents

Abstract

In a method for the production of pumping and/or guiding means for fluid machines, the pumping and/or guiding means being produced by blades arranged on the outer circumference of an annular or disc- shaped part via radial connecting webs, the blades are arranged with permanent deformation of the connecting webs relative to the blade carrier. In order to obtain a configuration affording optimum efficiency with simple design construction of radial flow pumping and/or guiding means for fluid machines, it is proposed that the connecting webs each be arranged on the blade carrier by means of the smallest possible cross section and that the blades be arranged in positions axially adjacent in the blade carrier by successive varying and/or spatial swivelling by means of bending and drilling of the connecting webs in their smallest possible cross sections in order to form a radial flow pumping and/or guiding means. <IMAGE>

Description

According to the preamble of claim 1, the invention is based on US Pat. No. 2,802,619.

From this document the production of an axial impeller of a turbomachine is known, the central blade carrier and the blades arranged on the outer circumference via connecting webs being made or stamped from a sheet metal. In a further manufacturing process, the blades are brought into the functional position by twisting the connecting webs about radially directed axes.

In the case of radial impellers of fluid-flow machines, in particular fluid-flow machines, the blades, which are made in one piece from a sheet metal with the blade carrier, are brought into a functional position by bending or bending. For example, DE-OS 1 628 222 shows a radial impeller made of sheet metal, the blade carrier, which cooperates directly with a shaft in a rotationally fixed manner, carrying blades which are formed from sections of an outer ring region and are each angled about a straight bending edge. Point with the straight bending edges between the blade carrier and blades this has a straight course in the radial direction and a relatively short length due to the formation of sections of the outer ring region. This simple design of the bucket is only sufficient for low conveying capacities.

In contrast, a better impeller through longer and curved or simply curved blades achieved a radial impeller known from DE-Gm 75 14 744. Here, the blades are also designed from sections of the integrally connected blade carrier and brought into a functional position by bending along curved bending edges. Since the blades extend from the outer blade carrier circumference limitation to the central region in order to achieve a relatively large length, there are relatively large gaps in the blade carrier between the positioned blades due to the sections of the blade carrier provided for their formation. In order to nevertheless achieve the desired delivery rate, the star-like blade carrier, which is connected in one piece to the blades, is arranged on a disk which can be connected in a rotationally fixed manner to a shaft. In addition to additional weight, the free edges of the gap boundaries of the star-shaped blade carrier running between the blades form flow losses due to eddy formation. In addition, this type of construction is associated with a high manufacturing outlay.

Another design of a radial impeller that can be produced from sheet metal with freely selectable curvatures of the blades and the maximum possible lengths is shown in DE-OS 33 43 752. To achieve the aforementioned blade design, the impeller is composed of individual segments, the number of which corresponds to the number of blades. Each of the segments that can be produced from sheet metal has a single piece along a boundary arranged blade on, while the other part of the segment forms a closed channel wall, which connects with its narrow side to the adjacent segment with the same contour. In addition to complex production, there is also the need for mechanical post-processing to achieve balanced runout.

Another example of the latter type of built radial impeller is finally shown in DE-OS 1 653 712. In this example, blade carriers and blades are each formed separately, the blades being able to be optimally designed, in particular spatially, to achieve a favorable fluid machine efficiency curved design. A disadvantage of this known arrangement of the blades, however, is the manufacturing and manufacturing outlay associated with the separate fixing of a blade in its two end regions.

The invention has for its object to further develop the manufacturing method described in the preamble of claim 1 such that radially flowed conveying and / or guiding devices of turbomachines with low material costs and gap-free blade carrier with efficiency-optimized blades with regard to the desired shape, maximum possible length and free design the blade curvature can be produced in a simple manner with a structurally simple structure of the respective device.

This object is achieved by the features specified in the characterizing part of claim 1.

The essence of the invention is the connecting web of each blade over such the smallest possible cross section to be tied to the blade carrier that this cross-section endures successive pivoting operations of the blade, such as, for example, bending transversely to the blade carrier and subsequent twisting of the said cross-section, for the radial positioning of the blade or the blades relative to the blade carrier in a functionally appropriate manner and additionally a relatively secure mounting of the blade or the blades in the final position or in the final positions. The function of the smallest possible cross-section thus corresponds to that of a universal joint which is subject to high friction, part of which retains every spatial position at the end of a force. This is a major advantage for the automated production of a conveyor and / or guide device. The smallest possible cross section is preferably formed by a one-piece connection of the connecting web to the blade carrier. This leads to the further substantial advantage that the blade carrier and blades with the connecting webs can be manufactured together from a piece of sheet metal in an economically advantageous manner in one operation. However, it is also possible to produce the smallest possible cross section, for example by means of a welding point. In both cases, the blades and the blade carrier can be designed geometrically freely independently of one another in the respective manufacturing process.

Before the blades are arranged in their smallest possible cross-sections in the blade carrier in the further manufacturing process according to a further characteristic feature of claim 1 in the blade carrier to form a radially flowed conveying and / or guiding device by successive different or spatial pivoting by means of bending and twisting the connecting webs, can they Blades can be shaped in a simple or multiple curved manner in a production-favorable sequence in an embodiment of the invention. In addition, the blades can be reinforced in the case of thin sheet metal and high stresses caused by beads. Finally, in order to achieve low flow losses through the curved and twisted cross sections of the connecting webs, it is proposed in a further embodiment that the blade carrier is formed in the outer peripheral region with recesses arranged in pairs, the mutual spacing of which defines the smallest possible width of the connecting web relative to the sheet thickness. With this configuration, the bent and twisted region of the connecting web can be arranged essentially between the two end faces of the blade carrier and the flow losses can thus be kept low. The prescribed configuration also makes it possible, in an advantageous manner, to strike the blades directly against the blade carrier without intermediate space after pivoting several times into the functional position.

The above-described, gap-free arrangement of the blades on one end face of the blade carrier offers the further advantage of the free choice of location and the type of additional connection of a blade to the blade carrier. Thus, in the case of blades that are not loaded too heavily, the smallest possible cross-sections of the connecting webs, which are permanently deformed by bending and twisting, can serve as attachment points of the blades on the blade carrier, additional attachment points being provided in the free end regions of the blades according to a further proposal of the invention. In the case of one-piece design of blades and blade carrier, the smallest possible cross section can be obtained by suitable choice of material with regard to high toughness The connecting web of this, in addition to the function of a universal joint subject to high friction, also serves as a holding and fixing device for each blade on the blade carrier. Associated with this in the automated manufacture of a conveying and / or guiding device is the advantage of a flawless mounting of each blade in the respective functional position relative to the blade carrier until the production of a further fixation located radially inward, in particular in the free blade end region. According to further claims, a material closure achieved by welding or soldering or a form closure achieved by plug connection can serve for this purpose.

The smallest possible cross-sections of the connecting webs achieved in recesses arranged in pairs in the outer circumferential area of a blade carrier, as already described above, enable the blades to be positioned on an end face of the blade carrier in a gap-free arrangement, which is an advantageous prerequisite for fixing the blades without additional measures represented by laser welding. Depending on the load on the blades, they can only be welded in the free end region or over the blade length at further points or continuously. Since with the gap-free arrangement of the blades, laser welding does not leave any traces of welding disturbing the flow, laser welding in combination with the manufacturing method according to the invention offers a radially flowed conveying and / or guiding device of a turbomachine, in particular in automated production.

Another welding process that is advantageous for automated production is hump pressure welding, in which one or more humps are arranged along a blade in / on the blade carrier. Since the blades come into contact with the blade carrier essentially without a gap at the end of the pressure welding, the connecting web is additionally designed to be compressible for the movement of the blades during the pressure welding. This is achieved by means of recesses in the outer circumferential region of the blade carrier which are arranged in a pair and are spaced radially further inwards, the compressed connecting webs not projecting beyond the end face of the blade carrier which faces away from the blade. The correct choice of the arrangements of the recesses lying radially further inward saves any reworking and also allows an impeller manufactured by the manufacturing method according to the invention to be arranged in the flow device with the smallest possible gap.

Particularly in the context of an automated manufacturing process with an integrated welding process, it is further proposed to achieve a flawless welded joint in the event of damage-free action of part of a welding device that the blades with counter-holding device are formed in the free end regions with radially directed contact edges. These contact edges can be radially directed boundaries of the blades or be formed in additional recesses on the suction edges of the blades.

The method claim 1 for the production of a radially flowed conveying and / or guiding device according to the invention applies both to a disk-shaped and thus planar blade carrier as well as to a spatially, in particular conical or spherical section-shaped blade carrier. In conjunction with a further proposal of the invention, a Open radial impeller of a turbomachine, which is designed in accordance with requirements, can advantageously be produced inexpensively by connecting the blade carrier to a hub part of a radial impeller. An advantageously simple manufacture of an open radial impeller with the least additional material expenditure is further achieved in that the blade carrier and hub part of the impeller, in particular a fluid-flow machine, are formed in one piece from sheet metal. Otherwise, the manufacturing method according to the invention is not limited to single-flow radial impellers. As another proposal describes, the blades can be arranged alternately on the blade carrier in order to achieve a double-flow radial impeller.

According to another proposal of the invention, the method for producing a closed radial impeller formed from only two sheet metal parts is advantageous. Here, the blade carrier with its blades forms one of the sheet metal parts, while a disk connected to a molded hub part forms the second sheet metal part. When combining the two aforementioned sheet metal parts to form a single-flow, closed radial impeller, the manufacturing method according to the invention can be used with regard to low manufacturing costs in that the blades are welded exclusively to the hub part disk, while the blades are welded to the cover ring of the closed radial impeller serving blade carrier only remain connected via the connecting webs. In order to minimize the mechanical load on these connecting webs in the smallest possible, permanently deformed cross section, the axially end regions of the blades from the hub part disk to the connecting webs can be used as free, essentially radially directed suction edges are executed. Since the blades are thus connected to the blade carrier serving as a cover ring essentially only in a punctiform manner, the punctiform connections of the connecting webs which are permanently deformed by bending and twisting in the smallest possible cross sections result in insignificant flow obstacles. Finally, the blade carrier serving as a cover ring in the case of a closed radial impeller can be designed according to a partial feature of a further proposal of the invention with an integrally molded suction mouth. On the one hand, this allows losses through backflow to be minimized and the axial inflow to be influenced favorably. In addition to the literal function and the function of a cover ring, the blade carrier thus also has the function of a carrier for the suction mouth of a closed radial impeller.

For a perfect and secure material connection of the blades arranged on a blade carrier with a disc arranged on a hub part to form a closed radial impeller, in a concrete embodiment of a proposal generally described further above, cutouts with radially directed contact edges are suggested in the suction edge region of the blades near the axis to train who serve the installation of counter-holding devices, in particular a welding electrode.

Finally, the method according to the invention, as already described above for a double-flow, open radial impeller, is also suitable for producing a double-flow, closed radial impeller.

A radial impeller produced by the method according to the invention is preferably used as a coolant pump wheel, in particular a water pump wheel for internal combustion engines. Compared to the known water pump wheels with relatively thick blades and relatively rough surfaces, which are produced either in the plastic injection molding process or in the metal casting process, in the water pump wheel produced according to the invention all parts in the water flow can be made very thin-walled with sufficient strength. This results in an optimally usable delivery cross-section of the water pump wheel with simultaneously reduced flow losses due to smooth surfaces of the sheet metal parts. The thus advantageously increased efficiency can serve in a redesign of a radial impeller as a water pump impeller to reduce its structural dimensions and, in conjunction therewith, for the favorable placement of the flow device on the internal combustion engine. The water pump wheel is preferably made of a stainless steel sheet.

Finally, a further proposal of the invention is directed to radial impellers of turbomachines, the blades of which have a relatively long radial extent at a small mutual angular distance. In order to be able to form a large number of blades as punched-outs which are integrally connected to the blade carrier via the connecting webs, the punched-out portions are formed with radial extensions of the blades fixed in the radial direction. So that when positioning the blades in front of an end face of the blade carrier, both the mechanical load on the connecting webs and the number of swivels are minimized, the blades are placed transversely to the blade carrier around radial axes running through the connecting webs in such a way that the blades subsequently join can be folded over the connecting webs in front of the desired end face of the blade carrier. This proposal is equally suitable for open and closed radial impellers, as well as for single and double flow wheel designs. In the case of larger angular spacings of the blades, the radial blade extensions can be achieved by punching out the blades with their main extensions arranged approximately in the circumferential direction of the blade carrier.

In the context of the invention, the above statements also apply analogously to a radially flowed stator.

• Fig. 1 ein ebenes Ausgangsblech,
• Fig. 2 das Blechstück gemäß Fig. 1 mit ausgestanzter zentrischer Öffnung,
• Fig. 3 das Blechstück nach Fig. 2 mit ausgestanztem Abdeckring und Schaufeln,
• Fig. 4 das Blechstück gemäß Fig. 3 mit zentrischer Umbördelung und teilweise umgeformten Schau­feln,
• Fig. 5 den Abdeckring gemäß Fig. 4 mit in axialer Richtung und teilweise radial einwärts umge­bogenen Schaufeln,
• Fig. 6 eine Draufsicht auf den Abdeckring mit Schaufeln gemäß Fig. 5,
• Fig. 7 eine Scheibe mit Nabe in Seitenansicht,
• Fig. 8 die Scheibe gemäß Fig. 7 in Draufsicht,
• Fig. 9 ein fertiges geschlossenes Radiallaufrad als Wasserpumpenrad gemäß der Erfindung mit zur deutlichen Darstellung teilweise fortgelas­senen Schaufeln in Seitenansicht,
• Fig. 10 das geschlossene Wasserpumpenrad in Draufsicht,
• Fig. 11 eine abgeänderte Ausführungsform eines Abdeckringes mit Saugmund und Schaufeln für ein geschlossenes Radiallaufrad ähnlich Fig. 5,
• Fig. 12 und 13 für ein Ausführungsbeispiel eines offenen Radiallaufrades eine Nabe mit ausgeformter Scheibe und einstückig angeordneten Schaufeln aus einem Blechstück,
• Fig. 14 das offene Radiallaufrad in Seitenansicht mit teilweise fortgelassenen Schaufeln,
• Fig. 15 das fertige, offene Radiallaufrad in Drauf­sicht,
• Fig. 16 und 17 ein mit einem Radiallaufrad kombinierbares, radial durchströmtes Leitrad mit einem Schaufelträger mit erfindungsgemäß ausgebil­deten und angeordneten Schaufeln,
• Fig. 18 das Leitrad in geschlossener Ausführung in Seitenansicht, und in
• Fig. 19 und 20 ein weiteres Ausführungsbeispiel eines Radial­laufrades mit Schaufeln in kleinem gegenseitigen Winkelabstand und relativ langen radialen Erstreckungen.

The invention is described with reference to exemplary embodiments shown in the drawing. Show it:

• 1 is a flat starting plate,
• 2 shows the piece of sheet metal according to FIG. 1 with a punched-out central opening,
• 3 the sheet metal piece according to FIG. 2 with punched-out cover ring and blades,
• 4 the sheet metal piece according to FIG. 3 with central flanging and partially formed blades,
• 5 with the cover ring according to FIG. 4 with blades bent in the axial direction and partially radially inwards, FIG.
• 6 is a plan view of the cover ring with blades according to FIG. 5,
• 7 is a disk with hub in side view,
• 8 is a top view of the pane according to FIG. 7,
• 9 shows a finished, closed radial impeller as a water pump impeller according to the invention with vanes partially omitted for clear illustration in a side view,
• 10 the closed water pump wheel in plan view,
• 11 shows a modified embodiment of a cover ring with suction mouth and blades for a closed radial impeller similar to FIG. 5,
• 12 and 13, for an exemplary embodiment of an open radial impeller, a hub with a shaped disk and blades arranged in one piece from a piece of sheet metal,
• 14 the open radial impeller in a side view with partially omitted blades,
• 15 the finished, open radial impeller in plan view,
• 16 and 17 a radial flow through a stator which can be combined with a radial impeller and has a blade carrier with blades designed and arranged according to the invention,
• Fig. 18, the stator in a closed version in side view, and in
• 19 and 20 a further embodiment of a radial impeller with blades at a small mutual angular distance and relatively long radial extensions.

First, a central, circular opening 2 is punched into a square piece of sheet metal 1, FIG. 1 (FIG. 2). In the further process step, a cover ring 3 is punched out with essentially triangular blades 4, each blade 4 being connected to the cover ring 3 via a connecting web 5 (FIG. 3).

This is then followed by an axial shaping or flanging on the inner circumference of the central opening to form a suction mouth 6 and an arcuate configuration of the blades 4, as shown in FIG. 4. In a further method step, the blades 4 are then bent at right angles and then partially radially inward, as shown in FIG. 5 in section and FIG. 6 in plan view.

7 and 8 show a truncated cone-shaped disk 7 likewise formed from a flat piece of sheet metal with a hub 8 integrally formed thereon, with bulges 9 at equal angular intervals in the edge region of the disk 7 and on a circle 9 corresponding to the inwardly bent ends of the blades 4 are designed such that end regions 10 and 11 of the blades 4 in the position according to FIGS. 5 and 6 come to lie opposite the hump 9 when the cover ring 3 and the disk 7 are brought into contact with one another in the axial direction. Then, in this position, a hump pressure welding is carried out, whereby the water pump impeller as a closed radial impeller 14 is in the finished state, as shown in FIGS. 9 and 10.

As FIG. 11 shows, cutouts 12 with radially directed edges 13 can be formed in blades 4a on the side facing away from the hub disc in the free end regions 11a, such that the welding tools applied in these free end regions 11a from the side facing away from the hub disc force the blades 4a against the can press opposing hump on the hub disc 7a, ie without the risk of slipping on the inclined edges of the blades 4a of the liberating cover ring 3a with flange 6a.

Of course, the exemplary embodiment described can be modified in many ways without departing from the basic idea of the invention. Thus, individual of the above-described process steps running in succession can also take place in a different chronological order (for example the step in accordance with FIG. 2 after the step in accordance with FIG. 3), or several steps may be carried out together (for example the steps in accordance with FIGS. 2 and 3). . In addition, as stated at the outset, other connection methods than the hump pressure welding method shown can also be used to connect the cover ring to the blades and the disk to the hub.

For an open radial impeller 16 according to FIGS. 14 and 15, a hub disk 17 with a molded hub 18 is formed from a piece of sheet metal similar to FIGS. 1 and 2, with blades 19 being punched out on the outer circumference of the hub disk 17. The blades 19, which are integrally connected to the disc 17 via connecting webs 20, have cutouts with their greatest radial extent, essentially in the circumferential direction of the disc 17. This material-saving arrangement of the cutouts for the blades 19 is advantageous with a relatively large angular distance between the blades 19. After an arch In a further method step, the blades 19 are designed to bend the blades at right angles, which is followed by a partially radially inward bending. If, as prescribed, the blades 19 are positioned in front of the end face 21 of the hub disk 17, the blades 19 are welded to bosses 22 of the disk 17.

FIG. 18 shows a closed stator 23 which can be assigned as a guide device to one of the radial impellers 14 or 16 shown in FIGS. 10 or 15 on the outflow side. The stator 23 comprises an annular blade carrier 24 formed from a piece of sheet metal and having blades 25 arranged by punching on the outer circumference. The straight blades 25 are arranged in a radial direction by bending and twisting the connecting webs 26. Via the blades 25, a circumferential ring 27 of the same shape as the blade carrier 24 is fixedly connected to the blade carrier 24 to form the stator 23.

A double-flow radial impeller 28, which preferably serves as a fan wheel, is shown in Fig. 20 and has on both sides of a flat blade carrier 29 arranged blades 30 and 30 '. The blade carrier 29 including all blades 30 and 30 'is punched from a flat piece of sheet metal, the aforementioned blades being arranged in one piece on the blade carrier 29 via connecting webs 31. Due to the large number of blades 30, 30 'and their relatively long radial extensions, the punched-out holes forming the blades are arranged so that the radial dimensions of the blades 30, 30' are achieved via their radial dimensions. Subsequently, the blades 30 are transverse to the blade carrier 29 in each case according to arrow A about radial axes 32 running through the connecting webs 31 provided that the blades 30 can then be folded over the connecting webs 31 in front of the end face 33 of the blade carrier 29 according to arrow B. Then the blades 30 'through the connecting webs 31 extending radial axes 34 to the blade carrier 29 each in such a manner according to arrow C that the blades 30' can then be folded over the connecting webs 31 in front of the end face 35 of the blade carrier 29. Finally, all blades 30, 30 'are firmly connected to the blade carrier 29.

Claims (23)

1. Process for the production of conveying and / or guiding devices for turbomachines,
- The conveying and / or guiding devices are produced with blades arranged on the outer circumference of an annular or disk-shaped part via radial connecting webs, and
- The part serving as the blade carrier and the blades made of sheet metal and
the connecting webs are also permanently deformed for the functional positioning of the blades relative to the blade carrier,
characterized,
- That the connecting webs are each arranged over the smallest possible cross-section on the blade carrier, and
- That the blades are arranged by successively different or spatial pivoting by bending and twisting the connecting webs in their smallest possible cross-sections in the blade carrier axially adjacent positions to form a radially flowed conveying and / or guiding device. 2. The method according to claim 1, characterized in that
that the blade carrier is formed in the outer peripheral region with recesses arranged in pairs,
- The mutual distance defines the smallest possible width of the connecting web relative to the sheet thickness. 3. The method according to claims 1 and 2, characterized in that the blades are curved. 4. The method according to claims 1-3, characterized in that the blades are provided with beads. 5. The method according to claims 1-4, characterized in that the blades are fixed in the free end region. 6. The method according to claim 5, characterized in that the blades are fixed by material closure (welding, soldering). 7. The method according to claim 6, characterized in that the blades are fixed by laser welding or hump pressure welding. 8. The method according to claim 7, characterized in that the blades for welding with counter-holding devices (counterelectrode during projection pressure welding) are formed in the free end regions with radially directed contact edges. 9. The method according to claim 5, characterized in that the blades are fixed by positive locking (plug connections). 10. The method according to one or more of claims 1- 9, characterized in that the blade carrier is connected to a hub part of a radial impeller. 11. The method according to claim 10, characterized in that the blade carrier and hub part of the impeller are integrally formed from sheet metal (Fig. 12 - 15). 12. The method according to one or more of claims 1-9, characterized in that the blade carrier is connected via the blades with a disc on a hub part of a radial impeller (Fig. 1 - 11). 13. The method according to one or more of claims 1-11, characterized in that
- That the small mutual angular distance and relatively long radial extents of the blades whose radial extents are achieved in radially directed cutouts, and
- The blades about radial axes extending through the connecting webs to the blade carrier are each placed transversely such that
- The blades can then be folded over the connecting webs in front of an end face of the blade carrier (Fig. 19). 14. The method claim 13, characterized in that the blades are arranged alternately on the blade carrier (Fig. 20). 15. A method for producing a radial impeller with a hub and this is bent substantially at right angles to the adjoining disk and an opposing cover ring, blades being formed between the disk and the cover ring, characterized in that a central opening is formed from a flat sheet metal and from the surrounding annular one The blades are stamped out of the sheet metal area and subsequently the blades are shaped and first bent at right angles in the direction of the hub disk and then partially bent radially inwards around an connecting web with the annular sheet metal area forming the cover ring serving as the blade carrier and then partially radially inward and an axial deformation on the inner circumference of the central opening of the cover ring or of the blade carrier is carried out and then the end regions of the blades are connected to the disk. 16. Radial impeller according to one or more of claims 1-12, in particular for fluid flow machines, with hub part (8) and non-rotatably connected disc (7) and an axially spaced, a suction mouth (6,6a) delimiting cover ring (3,3a) and blades (4, 4a) arranged between them,
characterized,
- That the cover ring (3,3a) with suction mouth (6,6a) and the blades (4,4a) consists of a one-piece piece of sheet metal (1) formed by punching, shaping and bending / twisting,
- That the disc (7) with the hub part (8) is also formed from a piece of sheet metal, and
- That both sheet metal parts are connected to one another via free, radially directed end regions (10, 11) of the blades (4,4a). 17. Radial impeller according to claim 16, characterized in that the blades (4,4a) from the hub part disc (7) to the respective connecting webs of the axially opposite cover ring (3,3a) or the blade carrier freely running suction edges ( 15) have. 18. Radial impeller according to claim 17, characterized in that cut-outs (12) with radially directed contact edges (13) are formed in near-axis suction edge regions of the blades (4 a). 19. Radial impeller according to one or more of claims 1-18, characterized by the use as a coolant pump wheel (14) for internal combustion engines. 20. Radial impeller according to one or more of claims 1-19, characterized by the use of a stainless sheet for the wheel parts. 21. Radial impeller according to one or more of claims 1-19 or 20, characterized by a protective layer resistant to aggressive media. 22. Radial impeller according to claim 13, characterized as a double-flow impeller (28), in particular as a fan wheel (Fig. 19 - 20). 23. Guide device according to one or more of claims 1-9,
- which is assigned to a radial impeller on the outflow side and comprises an annular blade carrier (24) and an axially spaced circumferential ring, characterized in that
- That the blade carrier (24) with the blades (25) from a one-piece, by punching, molding and Bending / twisting formed sheet metal piece, and
- That the blade carrier (24) and the circumferential ring (27) are connected to one another via the blades (25) (FIGS. 16-18).

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