Radial fan

Abstract

In a radial impeller, comprising a cover plate (14) having an inlet opening (50) and a support plate (12), which are connected to each other via a blade ring (17) having several blades (18), wherein the blades (18) each have two opposite side edges (19a, 19b), one of which is connected to the cover plate (14) and the other to the support plate (12), wherein the side edges (19a, 19b) each extend between a blade leading edge (20) and a blade trailing edge (21) opposite in a circumferential direction of the impeller, the blades (18) are each designed as a hollow profile and two blade halves (24, 25) are attached to each other and welded together in the region of the blade leading edge (20) and the blade trailing edge (21), defining a cavity (23) between them. exhibit.

Description

[0001] The invention relates to a radial impeller, with a cover plate having an inlet opening and a support plate, which are connected to one another via a blade ring having a plurality of blades, wherein the blades each have two opposite side edges, one of which is connected to the cover plate and the other to the support plate, wherein the side edges each extend between a blade leading edge and a blade trailing edge opposite in an impeller circumferential direction.

[0002] Such radial impellers have been known for a long time. One goal in the development of radial impellers is to provide a radial impeller that is highly efficient. Various approaches have been pursued in the past. For example, DE 10 2011 013 841 A1 discloses a radial fan wheel that has a cover disk and a support disk that are connected to one another via a blade ring. The blade ring has several blades that are inclined from the inside outwards against the direction of rotation, each blade having a blade leading edge and a blade trailing edge arranged further outwards in the radial direction. The efficiency of this radial fan wheel has been improved in that the blade leading edges, starting from the cover disk and towards the support disk, each have a straight course with a component in the radial direction and a component in the circumferential direction.

[0003] Another approach to improving efficiency is described in EP 2 942 531 A1, in which the impeller is manufactured as a single piece as an injection-molded part, with the blades having a 3D geometry.

[0004] Furthermore, document EP 2 835 539 A1 shows a method for producing a radial fan with hollow blades from two welded halves.

[0005] The object of the invention is to create a radial impeller of the type mentioned at the outset, which is characterized by high efficiency, is weight-optimized and can be manufactured cost-effectively.

[0006] This object is achieved by a radial impeller having the features of independent claim 1. Further developments of the invention are presented in the subclaims.

[0007] The radial impeller according to the invention is characterized in that the blades are each designed as a hollow profile and have two blade halves which are attached to one another and are connected to one another in the region of the blade leading edge and the blade trailing edge via a welded joint and which delimit a hollow space between them.

[0008] The hollow profile design of the blades results in weight savings compared to blades made of solid material. Such hollow profile blades are relatively easy to manufacture from two blade halves, which only need to be welded together in the area of ​​the leading and trailing edges. The blades are preferably made of light metal or a light metal alloy, with aluminum or an aluminum alloy being particularly suitable as a light metal or light metal alloy. Such aluminum alloys, in particular, have the advantage of increasing mechanical strength, ductility, and fracture toughness at low temperatures. They are also resistant to corrosion in seawater.

[0009] According to the invention, the blades each have an inlet end region tapering toward the blade leading edge, which is formed by convexly curved end sections of the two blade halves on the opposite outer surfaces of the blade halves, such that the inlet end region has a continuously curved outer contour extending over both blade halves. In this case, the blades each have an arcuately curved profile nose or "radius" at the blade leading edge, which is part of the profile of the blade. The two blade halves, together with the inlet end region, which has a continuously curved outer contour, form an airfoil profile that is aerodynamically optimized and, particularly compared to "sharp-edged blade leading edges," also contributes to overall efficiency improvement. The blades, designed as hollow profiles, have a 3D geometry.

[0010] Particularly preferably, the convexly curved end sections are each formed as formed sections produced by plastically forming a blade half blank without cutting. Embossing the blade half blanks is particularly suitable for plastically forming. In this case, the convexly curved end sections are embossed.

[0011] Particularly preferably, the welded joint is a laser welded joint. This type of laser weld has the advantage that the heat input during welding is relatively low. This limits the distortion of the parts to be welded due to the heat.

[0012] It is possible for the welded joint to have at least one weld seam extending substantially over the entire length of the blade leading edge and / or the blade trailing edge. Alternatively, it is conceivable for the welded joint to be created by means of a spot weld.

[0013] In a particularly preferred manner, the blades are designed as components separate from the cover disk and the support disk and are connected by fastening measures in the region of their side edges on the one hand to the cover disk and on the other hand to the support disk.

[0014] Particularly preferably, the fastening measures comprise a welded joint, with which the blades are welded to the cover disk on one side and to the support disk on the other. A laser welded joint is particularly suitable as a welded joint to reduce heat input.

[0015] In a particularly preferred manner, the fastening measures comprise, in addition to the welded connection, a form-fitting connection with which the blades are connected on the one hand to the cover disk and on the other hand to the support disk.

[0016] In a particularly preferred manner, the form-fitting connection is designed as a plug-in connection, with plug-in elements and counter-plug-in elements arranged on the one hand on the side edges of the respective blades and on the other hand on the cover or support disk, and assigned to one another.

[0017] Particularly preferably, the plug-in elements are designed as elongated plug-in pins, preferably plug-in tabs, and the counter-plug-in elements are designed as receiving openings, in particular receiving slots, that accommodate the plug-in tabs. The plug-in pins are expediently located on the blades, and the receiving openings are located on the cover and support disks. However, it would also be conceivable to form plug-in pins on the cover and support disks and receiving openings, in particular receiving slots, on the side edges of the blades.

[0018] In a particularly preferred manner, the elongated plug-in pins are adapted to the contour of the outer surfaces of the blade halves and are also convexly curved, wherein the contour of the receiving slots is adapted to the contour of the elongated plug-in pins.

[0019] The blades each have two outer surfaces facing away from each other, of which the front outer surface in the direction of travel, in particular a convexly curved one, represents the pressure side, and the opposite outer surface, which may be concavely curved, represents the suction side. It is possible for the elongated plug pins to be arranged on the side edges of the blades in such a way that the elongated plug pins are alternately assigned to the pressure side and the suction side. The elongated plug pins are therefore expediently located near the pressure side, forming a quasi-extension of the outer surface, with the next elongated plug pin along the side edge then being arranged on the suction side, quasi-as an extension of the suction side.

[0020] Particularly preferably, the blades are inclined from the inside outward against the direction of travel and are designed as backward-curved blades. The blade leading edge and / or trailing edge of a respective blade expediently has an arcuate shape extending from the cover disk toward the support disk.

[0021] The invention further comprises a method for producing a radial impeller according to one of claims 1 to 11, the method comprising the following steps: Providing two blade halves and assembling the two blade halves in such a way that a hollow profile is formed and the two blade halves together form a blade leading edge and a blade trailing edge, welding the two blade halves in the region of the blade leading edge and the blade trailing edge to form a blade, carrying out the above-mentioned method steps for producing all blades of the blade ring, connecting the blades in the region of their side edges on the one hand to the cover disk and on the other hand to the support disk.

[0022] It is advisable for the blade halves to be plastically formed before assembly, in particular by stamping, in order to produce convexly curved inner sections.

[0023] In a further development of the invention, the blades are positively connected to the cover and support disk via the combination of the plug-in pins on the receiving slots and then the plug-in pins are welded to the receiving slots.

[0024] It is advisable to weld on the outer side of the cover plate or support plate facing away from the blade ring.

[0025] A preferred embodiment is illustrated in the drawing and explained in more detail below. The drawing shows: Figure 1 is a perspective view of a preferred embodiment of the radial impeller according to the invention, Figure 2 is a perspective side view of a blade of the radial impeller of Figure 1 , Figure 3 another perspective view of the shovel of Figure 2 , Figure 4a longitudinal section through the support disk of the radial impeller of Figure 1, Figure 5a longitudinal section through the radial impeller of Figure 1, Figure 6an enlarged view of detail X of Figure 3 , Figure 7 a perspective view obliquely from above from the side of the support disk of the radial impeller of Figure 1 and Figure 8 a perspective view obliquely from above from the side of the cover plate of the radial impeller of Figure 1 .

[0026] The Figures 1 to 8show a preferred embodiment of the radial impeller 11 according to the invention. The radial impeller, which for the sake of simplicity could also be referred to as an impeller, is a component of a radial fan (not shown), which additionally has a fan drive (not shown) via which the radial impeller 11 can be driven in rotation. The radial fan can be one with a belt drive or with a direct drive. In the former case, a belt ensures the power transmission from the fan drive to the radial fan wheel 11. In the case of a directly driven radial fan, the fan drive can be attached to the radial impeller, for example by a drive shaft of the fan drive being coupled to a hub arrangement 13 of the radial impeller 11, which hub arrangement is formed on a support disk 12.

[0027] The Figures 1 to 8The preferred embodiment shown shows, purely by way of example, a radial impeller 11 which is intended for direct drive.

[0028] As particularly in the Figures 1 , 5 , 7 and 8 As shown, the radial impeller 11 has a cover plate 14 with a circular inlet opening 15 defining an intake diameter. The inlet opening 50 is located on a nozzle 15 protruding from the outside of the cover plate, which flares inward in a trumpet shape in the axial direction along a rotation axis 16. The trumpet-shaped flare of the nozzle 15 ensures improved deflection from the axial to the radial flow direction. The radius of the curvature can, for example, be in the range of 10% to 30% of the intake diameter.

[0029] Furthermore, a support disk 12 is provided, which is arranged coaxially with the cover disk 14. The cover and support disks 12, 14 are connected to each other via a blade ring 17. The previously mentioned hub assembly 13 is located on the support disk 12 and serves for coupling to a drive shaft of a fan drive (not shown). The outer diameter of the support disk 12 is smaller than or approximately equal to the outer diameter of the cover disk 14.

[0030] The blade ring 17 consists of several blades 18, each inclined from the inside outward against the direction of travel. In the present example, backward-curved blades 18 are provided.

[0031] The blades 18 each have two opposing side edges 19a, 19b, one of which is connected to the cover plate 14 and the other to the support plate 12. The side edges 19a, 19b each extend between a blade leading edge 20 and a blade trailing edge 21 opposite one another in the impeller's circumferential direction.

[0032] As particularly in Figure 6 As shown, the blades 18 are each designed as a hollow profile and have two blade halves 24, 25 which are attached to one another and are welded to one another in the region of the blade leading edge 20 and the blade trailing edge 21 via a welded joint 22 and which define a hollow space 23 between them.

[0033] As further stated in Figure 6As shown, the blades 18 each have an inlet end region 26 which tapers towards the blade leading edge 20 and which is formed by convexly curved end sections 29, 30 of the two blade halves 24, 25 facing away from one another, such that the inlet end region 26 has a continuously curved outer contour extending over both blade halves 24, 25.

[0034] As particularly in the Figures 5 and 7 As shown, the blades 18 are each twisted within themselves, ie the opposite side edges 19a, 19b of a respective blade 18 have different courses from one another.

[0035] The convexly curved end sections 29, 30 are each formed as forming sections produced by plastic forming, in particular stamping, of a blade half blank without cutting.

[0036] The blades 18 are each made of aluminum or an aluminum alloy. Combined with the hollow profile of the blades, this results in a weight saving compared to conventional blades made of solid sheet steel.

[0037] As particularly in the Figures 2 and 3 The blades 18 are shown as hollow-profile blades. The blade geometry can be formed from several axially offset sections perpendicular to the axis of rotation. Different inlet and outlet angles, as well as diameter ratios and blade radii, are used for each section. The final shape of the hollow-profile blade is formed from the blade geometry and a superimposed NACA profile geometry. The blades can therefore be designed like an airfoil profile.

[0038] As particularly in Figure 1As shown, the meridian contour 31 at the blade trailing edge 21 of the radial impeller 11 determines, in particular, the final shape of the blade 18. An important parameter for the inflow of the blades 18 is the so-called blade inlet angle β 1 . This is formed as the angle of a tangent to an inner root point of the blade 18 and a circumferential tangent passing through this root point. The blade inlet angle β 1,TS is different in the area of ​​the main disk from the blade inlet angle β 1,DS in the area of ​​the shroud.

[0039] The blade trailing edge 21 is arranged opposite the blade leading edge 20. A blade trailing angle β 2 is formed at the blade trailing edge 21, which is defined as the angle of a tangent to an outer root point of the blade to the circumferential tangent passing through this root point. Analogous to the blade leading edge β 1 formed at the blade leading edge 20, the blade trailing angle β 2,TS in the area of ​​the support disk can also be different from the blade trailing angle β 2,DS in the area of ​​the shroud.

[0040] As already mentioned, the blades 18 are each formed by assembling the two blade halves 24, 25 and subsequently welding them in the region of the blade leading edge 20 and the blade trailing edge 21. The welded joint provided for this purpose can expediently be designed as a laser welded joint, whereby the heat input into the blade halves to be welded during the welding process is relatively low. The blades are expediently formed at the blade leading edge 20 and at the blade trailing edge 21 by means of a weld seam (not shown) extending over the entire length of the blade leading edge and the blade trailing edge 21.

[0041] Another important aspect is the connection of the blades 18 on the one hand with the support disk 12 and on the other hand with the cover disk 14 in the region of the oppositely arranged side edges 19a, 19b.

[0042] As particularly in the Figures 2, 3 , 6 and 7 As shown, a combination of a welded connection with a form-fitting connection is used as a fastening measure for fastening the blades 18 on the one hand to the cover disk 14 and on the other hand to the support disk 12.

[0043] The form-fitting connection is designed as a plug-in connection, with plug-in elements and counter-plug-in elements arranged on the one hand on the side edges 19a, b of the respective blade 18 and on the other hand on the cover or support disk 14, 12 and assigned to one another.

[0044] As particularly in Figure 6 As shown, the plug-in elements are designed as elongated plug-in pins 32. The elongated plug-in pins 32 could therefore also be referred to as plug-in tabs. The mating plug-in elements are designed as receiving openings that accommodate the plug-in pins. In the case of elongated plug-in pins or plug-in tabs, the receiving openings are designed as receiving slots 33.

[0045] As particularly in Figure 6 As shown, the elongated plug pins 32 are adapted to the contour of the outer surfaces 27, 28 of the blade halves 24, 25 and are curved accordingly. The contour of the receiving slots 33 is adapted to the contour of the elongated plug pins 32.

[0046] As the overview of the Figures 2, 3 and 7 As shown, the opposing outer surfaces 27, 28 of a respective blade 18 are characteristically formed. The front outer surface in the running direction, which belongs to the front blade half 24, could also be referred to as the pressure-side outer surface 27, while the other outer surface on the rear blade half can also be referred to as the suction-side outer surface 28.

[0047] As particularly in Figure 7As shown, the elongated plug pins 32 are arranged alternately on the suction and pressure sides, i.e. alternately in the area of ​​the pressure-side outer surface 27 and the suction-side outer surface 28.

[0048] The design of the plug-in pins 32 can also already be carried out during the production of the two blade halves 24, 25, for example by punching out or stamping the elongated plug-in pins from a blade half blank.

[0049] As particularly in the Figures 1 and 8As shown, the support and cover disks 12, 14 have end regions 34, 35 projecting beyond a blade outlet diameter defined by the blade outlet edges 21 of the respective blades 18, which define an annular diffusion space or diffuser 36 having a diffuser outer diameter. A characteristic of the cross-section of the diffuser 36 is that it is not rectangular or trapezoidal, but is determined by the shape of the end region 35 of the support disk 12, which does not taper straight but is curved in an arcuate manner.

[0050] The manufacture of the radial impeller 11 essentially proceeds as follows: First, the two blade halves 24, 25 are prepared and assembled in such a way that a hollow profile is formed, and the two blade halves 24, 25 together form a blade leading edge 20 and a blade trailing edge 21. Next, of course, the two blade halves 24, 25 must be connected or fastened to one another, which is done by welding the two blade halves 24, 25 in the area of ​​the blade leading edge 20 and in the area of ​​the blade trailing edge 21. This creates a hollow profile blade.

[0051] All blades 18 required for the blade ring 17 are manufactured one after the other or simultaneously.

[0052] Next, the blades 18 are connected in the area of ​​their side edges 19a, 19b on the one hand to the cover disk 12 and on the other hand to the support disk.

[0053] A characteristic feature of the manufacturing process is that the blade halves 24, 25 were machined by plastic forming, particularly stamping, before being prepared and assembled. A convexly curved end section 29 was formed from a blade half blank. This convexly curved end section 29, together with the convexly curved end section 30 of the other blade half, forms the characteristically shaped inlet end region 26, which extends over both blade halves 24, 25 with a continuously curved outer contour.

[0054] The finished blades 18 are connected to the support disk 12 on the one hand and the cover disk 14 on the other hand by inserting the elongated plug pins 32 on the side edges of the blades 18 into the receiving slots 33 on the support disk 12 on the one hand and into the receiving slots 33 on the cover disk 14 on the other. The resulting plugs are then welded from the outside, i.e., from the outer side of the support disk 12 or the cover disks 14 facing away from the blade ring. Laser welding is also a suitable welding method here to reduce heat input.

[0055] If necessary, welding can also be carried out from the inside to stabilize the connection.

Claims

1. Radial impeller having a cover plate (14) with an inlet opening (50) and a support plate (12), said plates being connected to one another by means of a vane ring (17) having multiple vanes (18), wherein said vanes (18) each have two side edges (19a, 19b) opposite one another, one of which is connected to the cover plate (14) and the other to the support plate (12), wherein the side edges (19a, 19b) each extend between a vane inlet edge (20) and a vane outlet edge (21) which is opposite in a circumferential direction of the impeller, wherein the vanes (18) are each designed as a hollow profile and have two vane halves (24, 25) delimiting a cavity (23) between them which are applied to one another and are each connected to one another in the region of the vane inlet edge (20) and the vane outlet edge (21) by means of a welded connection, wherein the vanes (18) each have an inlet end region (26) which tapers towards the vane inlet edge (20) characterized in that the inlet end region (26) is formed by convexly curved end portions (29, 30) of the two vane halves (24, 25) on the outer faces (27, 28) of the vane halves (24, 25) facing away from one another, in such a manner that the inlet end region (26) has a continuously curved outer contour extending over both vane halves (24, 25).

2. Impeller according to Claim 1, characterized in that the convexly curved end portions (29, 30) are each designed as formed portions produced without machining by plastic forming of a vane half blank, in particular stamping, of a vane half blank.

3. Impeller according to one of the preceding claims, characterized in that the welded connection is a laser-welded connection.

4. Impeller according to one of the preceding claims, characterized in that the welded connection has at least one welded seam extending substantially over the entire length of the vane inlet edge (20) and / or the vane outlet edge (21).

5. Impeller according to one of the preceding claims, characterized in that the vanes (18) are designed as components which are separate from the cover plate (14) and the support plate (12) and are each connected in the region of their side edges (19a, 19b) firstly to the cover plate (14) and secondly to the support plate (12) by means of fastening measures.

6. Impeller according to Claim 5, characterized in that the fastening measures comprise a welded connection, with which the vanes (18) are each welded firstly to the cover plate (14) and secondly to the support plate (12).

7. Impeller according to Claim 6, characterized in that the fastening measures comprise, in addition to the welded connection, a form-fitting connection, with which the vanes (18) are connected firstly to the cover plate (14) and secondly to the support plate (12), wherein the form-fitting connection is designed as a plug connection with plug elements and mating plug elements assigned to one another formed firstly on the side edges of the respective vanes (18) and secondly on the cover or support plate (12, 14).

8. Impeller according to Claim 7, characterized in that the plug elements are designed as particularly elongate plug pins (32), preferably plug tabs, and the mating plug elements are designed as receiving openings, in particular receiving slots (33), receiving the plug tabs, wherein the plug pins (32) are preferably arranged on the vanes (18) and the receiving openings on the cover and support plate (12, 14).

9. Impeller according to Claim 8, characterized in that the elongate plug pins (32) are adapted to the contour of the outer surfaces (27, 28) of the vane halves (24, 25) and likewise have a convexly curved design, wherein the contour of the receiving slot (33) is adapted to the contour of the elongate plug pins (32).

10. Impeller according to one of the preceding claims, characterized in that the vanes (18) are tilted from the inside outwards against the running direction and are designed in the form of backwardly curved vanes (18).

11. Impeller according to one of the preceding claims, characterized in that the vane inlet edge (20) and / or the vane outlet edge (21) of a respective vane (18) has an arcuate profile starting from the cover plate (14) in the direction of the support plate (12).

12. Method for producing a radial impeller (11) according to one of claims 1 to 11, said method having the following steps: - provision of two vane halves (24, 25) each have a convexly curved end portion (29, 30) on outer faces (27, 28) facing away from one another and assembly of the two vane halves (24, 25) in such a manner that a hollow profile is formed and the two vane halves (24, 25) together form a vane inlet edge (20) and a vane outlet edge (21), wherein by assembling of the two convexly curved end portions (29, 30) an inlet end region (26) is formed which tapers towards the vane inlet edge (20), wherein the inlet end region (26) has a continuously curved outer contour extending over both vane halves (24, 25), - welding of the two vane halves (24, 25) in the region of the vane inlet edge (20) and the vane outlet edge (21) to form a vane (18), - implementation of the aforementioned method steps to produce all vanes (18) of the vane ring (17), - connection of the vanes (18) in the region of the side edges (19a, 19b) thereof, firstly to the cover plate (14) and secondly to the support plate (12).

13. Method according to Claim 12, characterized in that the vane halves (24, 25) are each plastically formed prior to assembly, in particular stamped, in order to produce convexly curved inner portions (29, 30).

14. Method according to Claim 12 or 13, characterized in that the vanes (18) are connected to the cover and support plate (14, 12) in a form-fitting manner via the combination of plug pins (32) and the receiving slot (33) and the plug connections of the plug pins (32) with the receiving slots (33) are then welded, wherein the welding preferably takes place on an outer side of the cover plate (14) or support plate (12) facing away from the vane ring (17).

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