Method for producing a fan wheel, fan wheel and fan

Abstract

The invention relates to a method for producing a fan wheel (1), - wherein the fan wheel (1) has fan blades (3) extending from a hub (2) and a shroud ring (4) surrounding the fan blades (3) at their ends remote from the hub and rotating with the fan wheel (1), - wherein the shroud (4) has radial widenings (16) and locations (18) without radial widenings (16) on a rear edge (7), - wherein the fan wheel (1) is manufactured by means of plastic injection moulding. This allows the fan wheel (1) to be manufactured quickly and cost-effectively.

Description

[0001] The present invention relates to a method for producing a ducted fan wheel. The invention also relates to a ducted fan wheel produced by this method and to a fan, in particular a viscous fan in a motor vehicle, comprising at least one such ducted fan wheel.

[0002] Fans with ducted fan wheels are already widely used, particularly in automotive engineering. A major advantage of such ducted fan wheels over ductless fan wheels is that, due to their co-rotating shroud, they are less sensitive to the size of the air gap between the outer diameter of the ducted fan wheel and the inner diameter of, for example, an inlet nozzle. With ductless fan wheels, however, efficiency decreases with increasing air gap between the inlet nozzle and the fan wheel and also generates unpleasant flow noise.However, when using fan wheels in internal combustion engines, there is a conflict between maintaining the smallest possible air gap between the fan wheel and the intake nozzle to achieve the highest possible efficiency, and maintaining the largest possible air gap to reliably prevent vibration-induced collisions between the fan wheel and the intake nozzle. Therefore, ducted fan wheels offer significant advantages, particularly when used in internal combustion engines.

[0003] Furthermore, it has been shown that ducted fan wheels with shrouds that expand radially in the direction of flow, i.e. from a leading edge to a trailing edge, bring aerodynamic advantages, since such a shroud shape leads to an increased volume flow and thus a higher efficiency.

[0004] However, the disadvantage of such ducted fan wheels with a shroud that expands radially in the direction of flow is that they can only be manufactured using injection molds with vanes, whereby such injection molds with vanes mean increased tool costs and wear out more quickly, which results in higher unit costs overall for such ducted fan wheels.

[0005] The present invention therefore addresses the problem of providing a method for producing a shrouded fan wheel with high efficiency and smooth running, which is at the same time cost-effective and easy to produce.

[0006] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0007] The present invention is based on the general idea of ​​specifying a method for producing a ducted fan wheel, wherein a trailing edge geometry of a shroud of such a ducted fan wheel is designed such that this ducted fan wheel can be produced using a sliderless tool, for example a sliderless plastic injection molding tool. The ducted fan wheel to be produced has fan blades extending from a hub and a shroud that is firmly connected to the fan blades at their ends remote from the hub, wherein the shroud has radial widenings and locations without radial widenings at a trailing edge. At the radial widenings, the shroud has an outer diameter at the trailing edge that is larger than the outer diameter at the leading edge of the shroud.At the points without radial expansions, the shroud has an outer diameter at the trailing edge that corresponds to the outer diameter at the leading edge of the shroud. The shroud is designed in such a way that the entire shrouded fan wheel can be manufactured in one piece using a slide-less plastic injection mold. The shroud is manufactured without undercuts so that the previously mentioned slide-less plastic injection mold can be used. This is achieved according to the invention in that the radial expansion at the trailing edge of the shroud of the shroud fan wheel is no longer completely circumferential, but only in individual circumferential segments that are interrupted by the points without radial expansions. These points without radial expansion represent contact areas where a blade trailing edge of a respective fan blade touches the shroud.By using a sliderless tool, significantly shorter cycle times can be achieved compared to a tool with sliders, and tool costs are significantly reduced. The service life of such a sliderless tool is also significantly increased due to reduced wear compared to a tool with sliders. Overall, the design of the fan impeller and the resulting use of a sliderless tool can significantly reduce the manufacturing costs of the fan impeller.

[0008] The present invention is further based on the general idea of ​​specifying a ducted fan wheel manufactured according to the method described in the previous paragraphs. This makes it possible to transfer the advantages described with regard to the method in the manufacture of the ducted fan wheel to the ducted fan wheel. Specifically, these advantages lie in particular in cost-effective and simple production, since a slide-less plastic injection mold can be used for production, which requires lower tool costs and has less wear, as well as allowing shorter cycle times, which overall means that the ducted fan wheels can be manufactured more cost-effectively. In addition, ducted fan wheels of this type with radial widenings arranged on a trailing edge have a higher efficiency, whereby a higher volume flow can be conveyed with the same power.

[0009] In an advantageous development of the fan wheel according to the invention, the shroud ring is cylindrical at a leading edge. This makes it possible to run the fan wheel with its leading edge in an inlet nozzle, thereby achieving a high volume flow and thus also a high level of efficiency.

[0010] In a further advantageous embodiment of the shrouded fan impeller according to the invention, an outer radius of the shroud ring at its trailing edge varies in the circumferential direction. In contrast to shrouded fan impellers known from the prior art, which were continuously radially widened at the trailing edge of the shroud ring and thus could not be manufactured with a slide-less tool, the circumferentially varying outer radius of the shroud ring at its trailing edge allows a slide-less plastic injection mold to be used to manufacture the shrouded fan impeller according to the invention, which significantly reduces manufacturing costs.

[0011] In a particularly preferred embodiment of the ducted fan impeller according to the invention, the fan blades are integrally connected to the shroud ring by a leading edge and a trailing edge, the shroud ring being cylindrical both in a contact area with the leading edge of the respective fan blade and in a contact area of ​​the trailing edge of the respective fan blade with the shroud ring. This inventive feature avoids an otherwise occurring undercut in the contact area between the trailing edge of the blade and the shroud ring, thus enabling the use of a slide-less tool for the first time.

[0012] In a further advantageous embodiment of the ducted fan wheel according to the invention, such a widening is arranged on the trailing edge of the shroud ring in the circumferential direction between two trailing edges of two adjacent fan blades. Between two circumferentially adjacent blade trailing edges, the trailing edge of the shroud ring thus widens radially outward, which can improve the aerodynamics and efficiency of the ducted fan wheel according to the invention. By reducing the outer radius in the contact area of ​​the respective trailing edge of a fan blade with the shroud ring to a radius of the leading edge of the shroud ring, an undercut that would require a slider can be avoided.

[0013] In a particularly preferred embodiment of the ducted fan impeller according to the invention, the radial expansion of the shroud extends over a maximum of 50% of the axial height of the ducted fan impeller. This makes it possible to insert the ducted fan impeller according to the invention up to halfway into an inlet nozzle of a fan, in particular a viscous fan, and thus achieve a particularly high level of fan efficiency.

[0014] The hub of the ducted fan wheel is designed to be pot-shaped. This pot-shaped design allows for significant resource savings and weight savings, which further reduces the manufacturing costs of the ducted fan wheel and allows for the use of lighter bearings.

[0015] In a particularly preferred embodiment, stiffening ribs extending in the axial direction, i.e., in the direction of flow, are formed on an inner side of the cup-shaped hub. These stiffening ribs taper from a hub base across a hub wall to a hub edge. The reinforcing ribs are thus arranged in a triangular shape between a hub wall and a hub base and taper along the hub wall from the hub base to the hub edge. Using such stiffening ribs, the entire hub can be designed with thinner walls, which in turn allows for both weight and cost advantages through reduced material usage.

[0016] In a further embodiment of the shrouded fan impeller according to the invention, an inner side of the shroud ring in the region of the radial widenings is also widened or cylindrical and thus not radially widened. The first embodiment offers the great advantage that it can be manufactured with significantly less material and is therefore more cost-effective and lightweight. In the second embodiment, in which the inner side of the shroud ring in the region of the radial widenings is cylindrical, i.e. has the same inner diameter at the rear edge as at the front edge of the shroud ring, the area between the inner side of the shroud ring and the outer side of the widening is filled with plastic.Although this is not as advantageous as the first solution in terms of resource use and weight, it still allows the use of a slide-less plastic injection mold, which means that a highly efficient shrouded fan impeller can still be produced at comparatively low unit costs.

[0017] The present invention is further based on the general idea of ​​equipping a fan, in particular a viscous fan in a motor vehicle, with at least one shrouded fan impeller according to one of the preceding paragraphs, wherein the shrouded fan impeller is arranged with a leading edge of its shroud ring in an inlet nozzle. The fan thus has, for example, a radiator and the described fan, which has an inlet nozzle connected to the radiator at one end and in which a shrouded fan impeller according to the invention is arranged so as to rotate with its leading edge at the other end. This makes it possible to realize a fan that is not only cost-effective but also highly efficient.

[0018] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

[0019] It is understood that the features mentioned above and those to be explained below can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the present invention. Components mentioned above and to be mentioned below of a higher-level unit, such as a device, an apparatus, or an arrangement, which are designated separately, may form separate parts or components of this unit or be integral areas or sections of this unit, even if this is shown differently in the drawings.

[0020] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0021] They show, schematically Fig. 1 a fan impeller according to the invention in an oblique view, Fig. 2 a jacket fan wheel according to the invention in a front view, Fig. 3 a detailed view of the fan wheel according to the invention from the front, Fig. 4 a sectional view through a shroud fan wheel according to the invention in an alternative embodiment with a material accumulation between an inner side of the shroud ring and the radial widening, Fig. 5 a further sectional view through the fan wheel according to the invention in the area between two fan blades, Fig. 6 a sectional view along the trailing edge of a fan blade.

[0022] According to the Fig. 1 to 6, a ducted fan wheel 1 according to the invention comprises a hub 2 and fan blades 3 extending outward therefrom, and a shroud ring 4 enclosing the fan blades 3 at their ends remote from the hub and rotating with the ducted fan wheel 1. If the ducted fan wheel 1 rotates about an axis 5 in the direction of rotation 6, an air flow 8 can be conveyed via the ducted fan wheel 1 according to the invention.

[0023] The shroud 4 has a leading edge 9 and a trailing edge 7, while the individual fan blades 3 each have a leading edge 10 and a trailing edge 11.

[0024] At the front edge 9, the shroud 4 is cylindrical and can therefore be cut into a Fig. 1 indicated inlet nozzle 12 of a fan 13. The individual fan blades 3 have a suction side 14 and a pressure side 15.

[0025] At the trailing edge 7, the shrouded fan wheel 1 according to the invention now has radial widenings 16, which improve the aerodynamics of the shrouded fan wheel 1 according to the invention and lead to an increased volume flow and thus improved efficiency. The shroud ring 4 thus widens in the area of ​​the radial widenings 16 in the flow direction 8.

[0026] In order to be able to manufacture the fan wheel 1 according to the invention cost-effectively and simply by means of plastic injection molding, the radial widenings 16 are arranged in the circumferential direction 17 only between two adjacent blade trailing edges 11 in the circumferential direction 17. However, at the respective blade trailing edges 11, a location 18 is provided at which no radial widening 16 is arranged, so that at this location 18 the trailing edge 7 has the same radius as the leading edge 9, as is also the case Fig. 6. At point 18, the shroud 4 is deformed inwards again due to the lack of a radial widening 16. A transition from the radial widening 16 to point 18, or vice versa, occurs without a jump or kink. An outer radius of the trailing edge 7 of the shroud 4 of the shroud fan wheel 1 according to the invention varies in the circumferential direction 17 and is larger in the region of the radial widenings 16 than at points 18, where it corresponds to the outer radius of the leading edge 9. At the radial widenings 16, the shroud 4 has an outer diameter at the trailing edge 7 that is larger than the outer diameter at the leading edge 9 of the shroud 4, while at points 18 without radial widenings 16, it has an outer diameter at the trailing edge 7 that corresponds to the outer diameter at the leading edge 9 of the shroud 4.

[0027] The individual fan blades 3 are connected to the shroud 4 both by their leading edge 10 and by their trailing edge 11, the shroud 4 being cylindrical both in a contact area with the leading edge 10 and in a contact area with the trailing edge 11, so that at this point 18 the outer radius of the leading edge 9 corresponds at least substantially to the outer radius of the trailing edge 7 of the shroud 4.

[0028] If one considers the widenings 16 according to the Fig. 4 - 6, it can be seen that these extend over a maximum of 50% of an axial height H of the shrouded fan wheel 1 according to the invention. The 50% of the shroud ring 4 located towards the front edge 9 thus have a constant diameter and thus a cylindrical shape and can be inserted into the inlet nozzle 12.

[0029] If one further examines the ducted fan wheel 1 according to the invention, it can be seen that its hub 2 is cup-shaped, with a hub base 19 and an adjoining hub wall 20, which ends at a hub edge 21. Such an embodiment offers the great advantage that the hub 2 itself can be formed with comparatively little material and is therefore not only lightweight, but also resource-saving and cost-effective. On an inner side 22 of the cup-shaped hub 2, i.e. on an inner side of the hub wall 20, stiffening ribs 23 can be arranged which run in the axial direction, i.e. parallel to the axis 5, and which taper starting from the hub base 19 along the hub wall 20 to the hub edge 21, as is shown in the Fig. 4 - 6. Such stiffening ribs 23 enable a further reduction in the material of the hub 2, whereby the entire fan wheel 1 can be made even lighter, with less material and thus more cost-effectively, and also requires only smaller or lighter bearings.

[0030] Looking at the Fig. 4 and Fig. 6, it can be seen that in the case of the jacket fan wheel 1 according to the invention, an inner side 24 of the casing ring 4 on the suction side 14 of the respective fan blade 3 is cylindrical, while on the pressure side 15 (compare Fig. 5) also widens outwards in the direction of flow of the air flow 8 in the area of ​​the radial widenings 16. Purely theoretically, the fan wheel 1 according to the invention could also be manufactured with a slide-less plastic injection mold, provided that a region 25 lying radially between the inner side 24 and the widening 16 is made solid, as is the case according to the Fig. 4. However, such a massive design leads to an accumulation of material in area 25, which would not only make the ducted fan wheel 1 heavier but would also require a greater use of resources. Overall, the production of such a ducted fan wheel 1 would thus also be possible within the meaning of the invention, but not preferred.

[0031] In general, the ducted fan wheel 1 according to the invention can be manufactured, for example, by means of plastic injection molding in a slide-less plastic injection molding tool, although, theoretically, production by means of metal die casting in a slide-less die-casting tool is also conceivable. Aluminum, in particular, could be used here. Alternatively, the ducted fan wheel 1 according to the invention could also be manufactured by means of ceramic injection molding in a slide-less ceramic injection molding tool. Manufacturing the ducted fan wheel 1 according to the invention from plastic offers the great advantage that it is not only lightweight but also cost-effective. A lightweight design of the ducted fan wheel 1 also enables a weight-reduced design of a fan 13 equipped therewith and, moreover, the use of a smaller, lighter, and more cost-effective bearing for supporting the ducted fan wheel 1.

[0032] Overall, due to the special geometry of the shroud 4 of the shroud fan impeller 1 according to the invention, it can be manufactured using a slide-less plastic injection mold, which is significantly more cost-effective than a plastic injection mold equipped with slides, since a slide-less plastic injection mold requires lower tool costs and is also more wear-resistant. Shorter cycle times are also possible with a slide-less plastic injection mold.

[0033] However, due to the area being reduced only in the area of ​​the points 18 with regard to the radial expansions 16, the aerodynamic advantages associated with such expansions 16, such as a higher volume flow and a concomitant higher efficiency, can still be achieved.

Claims

[1] Method for producing a fan wheel (1), - wherein the fan wheel (1) has fan blades (3) extending from a hub (2) and a shroud ring (4) enclosing the fan blades (3) at their ends remote from the hub and rotating with the fan wheel (1), - wherein the shroud (4) has radial widenings (16) and locations (18) without radial widenings (16) on a rear edge (7), - wherein the fan wheel (1) is manufactured by means of plastic injection molding. [2] Method according to claim 1, characterized by that the fan wheel (1) is manufactured using a slide-less plastic injection mold. [3] Fan wheel (1) manufactured by the method according to claim 1 or 2. [4] Fan wheel according to claim 3, characterized by that the shroud ring (4) is cylindrical at a front edge (9) of the shroud fan wheel (1). [5] Fan wheel according to claim 3 or 4, characterized by that the fan blades (3) are connected to the shroud (4) by a blade leading edge (10) and a blade trailing edge (11), wherein the shroud (4) is cylindrical both in a contact area with the blade leading edge (10) and in a contact area with the blade trailing edge (11). [6] Fan wheel according to claim 5, characterized by that an expansion (16) is arranged on the trailing edge (7) of the shroud (4) in the circumferential direction (17) between two blade trailing edges (11) of two adjacent fan blades (3). [7] Fan wheel according to one of claims 3 to 6, characterized by that the radial widenings (16) of the shroud ring (4) extend over a maximum of 50% of an axial height (H) of the shroud fan wheel (1). [8] Fan wheel according to one of claims 3 to 7, characterized by that the hub (2) is cup-shaped. [9] Fan wheel according to claim 8, characterized bythat stiffening ribs (23) are formed on an inner side (22) of the cup-shaped hub (2), which stiffen starting at a hub base (19) over a hub wall (20) to a hub edge (21). [10] Fan (13), in particular a viscous fan in a motor vehicle, with an inlet nozzle (12) and with at least one jacket fan wheel (1) according to one of claims 3 to 9, which is arranged with a front edge (9) of its jacket ring (4) in the inlet nozzle (12).

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