One-piece fan wheel and method for its manufacture

Abstract

The invention relates to a one-piece fan wheel (2) for an air conveying device of a household appliance, comprising a central section (4) for fastening the fan wheel (2) to a shaft of the air conveying device for driving the fan wheel (2) and a plurality of air conveying elements (6) for conveying the air, wherein the air conveying elements (6) are arranged uniformly distributed over the circumference of the central section (4) and each extend radially outwards, characterized in that the fan wheel (2) is designed as a one-piece sheet metal part and the air conveying elements (6) are each arranged on a blade (8) of the fan wheel (2), wherein the blades (8) are arranged uniformly distributed over the circumference of the central section (4) and extend radially outwards from the central section (4) in such a way thatthat between directly adjacent wings (8) the sheet metal part has a gap (10) extending from the free ends of these wings (8) to a gap root. Furthermore, the invention relates to a method for producing a one-piece fan wheel (2).

Description

The invention relates to a one-piece fan wheel of the type mentioned in the preamble of claim 1 and to a method for producing a one-piece fan wheel.Cooking devices of this type having a cooking chamber and fan wheels for cooking devices are already known from the prior art in a multiplicity of embodiments, for example from the publication EP 3 726 930 B1. The known one-piece fan wheels comprise a central section for fastening the fan wheel to a shaft of the air conveying device for driving the fan wheel and a plurality of air conveying elements for conveying the air, wherein the air conveying elements are arranged distributed uniformly over the circumference of the central section and each extend radially outwards.The invention thus addresses the problem of improving a one-piece fan wheel and a method for producing the same.According to the invention, this problem is solved by a one-piece fan wheel having the features of patent claim 1, which is characterized in that the fan wheel is formed as a one-piece sheet metal part and the air conveying elements are each arranged on a blade of the fan wheel, wherein the blades are arranged distributed uniformly over the circumference of the central portion and extend radially outwards starting from the central portion in such a way that the sheet metal part has a gap extending as far as a gap root between directly adjacent blades starting from free ends of these blades. Furthermore, this problem is solved by a method with the features of claim 5. Advantageous embodiments and further developments of the invention are evident from the following dependent claims.The advantage which can be achieved with the invention is, in particular, that a one-piece fan wheel and a method for producing the same are improved. On account of the configuration according to the invention of the one-piece fan wheel and of the method for producing a one-piece fan wheel, on the one hand a significant weight reduction in the case of a one-piece fan wheel is made possible in comparison with the prior art with an at least constant flow speed of the fluid conveyed therewith, with the result that the energy required for a rotation of this fan wheel is significantly reduced. This is advantageous in particular for fan wheels according to the invention which are designed as fan wheels which change the direction of rotation, that is to say fan wheels which can be rotated in one or the other direction of rotation depending on the operating state. The reduced mass to be rotated has proven to be advantageous both during acceleration and also during deceleration of the fan wheel according to the invention. In comparison with the prior art, a weight reduction of up to 25% can be realized by means of the invention. Accordingly, it is possible, with the same power as in the prior art, i.e. with comparable flow speeds of the air, to operate the fan wheel with a lower rotational speed in the fan wheel according to the invention. The response behavior of the fan wheel according to the invention is also substantially improved in the case of a change in the rotational direction of the fan wheel, provided that it is a fan wheel changing the rotational direction, on account of the weight reduction. On the other hand, the one-piece fan wheel according to the invention can be produced in a very simple manner from a constructional and manufacturing standpoint by means of the method according to the invention.In principle, the one-piece fan wheel according to the invention can be freely selected within wide suitable limits in terms of type, mode of operation, material and dimensioning. The same also applies to the method according to the invention. For example, the one-piece fan wheel according to the invention can be suitably designed for a domestic appliance, for example for a steam cooker. However, the invention can also be used advantageously in other domestic appliances. Furthermore, the invention is not limited to household appliances. The invention can also be used in commercial appliances, that is to say appliances for professional use. The term "fan wheel" is to be interpreted broadly, so that not only fans but also fans or the like are included in particular. The fan wheel according to the invention can have a base plate with the central section for fastening the fan wheel to the shaft running perpendicular to the base plate and the blades with the plurality of air conveying elements. The base plate with the wings can be planar.An advantageous further development of the one-piece fan wheel according to the invention provides that the sheet metal part is designed as a bent part for realizing the vanes with the air conveying elements. In this way, the construction and the production are further simplified.A further advantageous development of the one-piece fan wheel according to the invention provides that the sheet metal part is designed as an embossed part for stiffening the central section and / or the vanes, preferably that the central section and the vanes have a single, common embossed portion, particularly preferably that this embossed portion has a circular ring contour which spatially separates the central section from the vanes and has radial rib contours which merge into the individual vanes. This ensures the rigidity of the one-piece fan wheel according to the invention, which is required for robust and long-lived operation, in a simple manner, despite a lightweight construction. By means of the preferred embodiment of this refinement, this can be realized with little outlay in terms of production technology. This applies in particular to the particularly preferred embodiment of this refinement. The term "embossing" is to be interpreted broadly, so that all suitable types of deep drawing or the like are also included.Another advantageous development of the one-piece fan wheel according to the invention provides that the respective gap extends, starting from the free ends corresponding thereto, in a triangular manner up to the gap root of this gap, which is designed as a triangle tip, preferably that this gap has an opening angle of 60° and / or has a gap depth of 30 mm, which is measured from an imaginary circular path of the free ends up to the gap root. In this way, the respective gap can be implemented in a very simple manner from a constructional and manufacturing standpoint without the stability of the one-piece fan wheel according to the invention substantially suffering. The preferred embodiment of this refinement specifies a configuration of the respective gap which is particularly relevant for practice. The gap root formed as a triangle tip can also be rounded.As already stated above, the process according to the invention is likewise freely selectable within wide suitable limits.A particularly advantageous development of the method according to the invention provides that the method has the following method steps in the stated sequence: production of a blank of the fan wheel from a one-piece sheet metal part, wherein the blank has the central section and the prefabricated vanes extending radially outwards from the central section, and wherein the prefabricated vanes each have, on the same side edge, a slot as far as a slot root for realizing the air conveying elements, preferably that the respective slot is formed as a notch; To realize the air conveying element corresponding to the respective wing, placing a part of this wing at an angle to a rest of this wing, preferably at an angle of 90° to the rest of this wing, wherein the aforementioned part of the respective wing on the side with the slot extends on the one hand from the free end of this wing as far as the slot and on the other hand from the side edge of this wing as far as the slot root; bending the respective wing about a bending axis running along the former slot in the direction of the central section in such a way that a bent section of this wing having the free end of this wing bears against a rest of the wing, wherein the air conveying element corresponding to this wing protrudes freely outwards from the bent section. As a result, the method according to the invention is realized in a very simple and at the same time reliable and functionally reliable manner.An advantageous further development of the aforementioned embodiment of the method according to the invention provides that at the end of the aforementioned method, i.e. after the bending of the respective wing, the bent section of the respective wing is connected to the rest of this wing in a force-transmitting manner, preferably that this force-transmitting connection is formed as a cohesive connection, particularly preferably that this cohesive connection is formed as a spot weld. In this way, it is ensured that the two sections of the respective wing that are in contact with one another remain aligned in the desired relative position with respect to one another even during operation. The connection can be implemented by means of the preferred and in particular by means of the particularly preferred embodiment of this refinement in a manner which is very simple in terms of design and production technology.Furthermore, an advantageous further development of one of the two latter developments provides that at the beginning of the aforementioned method, i.e. during the pre-assembly of the blank, the blank is embossed in the region of the central section and / or in the region of the vanes for the purpose of stiffening the one-piece fan wheel, preferably that the central section and the vanes are embossed in a single working step, particularly preferably that the central section and the vanes have a single, common embossing. As already explained above, this ensures the rigidity of the one-piece fan wheel according to the invention, which is required for robust and long-lived operation, in a simple manner, despite a lightweight construction. The embossing can be produced by means of the preferred embodiment of this refinement in a labor-saving manner. This applies in particular to the particularly preferred embodiment of this refinement.An exemplary embodiment of the invention is illustrated purely schematically in the drawings and is described in more detail below. It shows FIGS. 1 to 7 show an exemplary embodiment of the method according to the invention for producing the one-piece fan wheel according to the invention in a step by step illustration, with the fan wheel according to FIGS. 1 to 6 in each case in a perspective view and according to FIG. 7 in a front view, and FIG. 8 shows the exemplary embodiment of the fan wheel according to the invention in a partial enlarged view corresponding to FIG. 7.FIGS. 1 to 8 show an exemplary embodiment of the invention purely by way of example.The one-piece fan wheel 2 according to the invention produced by means of the method according to the invention is designed for an air conveying device, not shown in detail, of a domestic appliance designed as a steam cooker. The steam cooker is likewise not shown in detail. The fan wheel 2 comprises a central section 4 for fastening the fan wheel 2 to a shaft, not shown, of the air conveying device for driving the fan wheel 2 and a total of seven air conveying elements 6 for conveying the air, likewise not shown, wherein the air conveying elements 6 are arranged distributed uniformly over the circumference of the central section 4 and each extend radially outwards. The air conveying elements 6 are each aligned here on a surface center point 7 of the central section 4, so that the air conveying elements 6 run along straight lines emanating from the surface center point 7 in the form of a ray. The fan wheel 2 has an opening in the surface center point 7 for receiving the shaft driving the fan wheel 2.According to the invention, the fan wheel 2 is formed as a one-piece sheet metal part and the air conveying elements 6 are each arranged on a blade 8 of the fan wheel 2, wherein the blades 8 are arranged distributed uniformly over the circumference of the central portion 4 and extend radially outwards starting from the central portion 4 in such a way that between blades 8 directly adjacent to one another, starting from free ends of these blades 8, the sheet metal part has a gap 10 reaching as far as a gap root. The fan wheel 2 here has a base plate with the central section 4 for fastening the fan wheel 2 to the shaft running perpendicular to the base plate and the blades 8 with the plurality of air conveying elements 6. The base plate with the wings 8 is configured planar in the present exemplary embodiment. The gap root of the gap 10 is rounded here. The air conveying elements 6 project from the plane of the drawing of FIG. 7 in FIG. 7. In the present exemplary embodiment, the respective gap 10 extends, starting from the corresponding free ends of the directly adjacent wings 8, in a triangular manner up to the gap root of this gap 10, which is designed as a triangle tip, wherein this gap 10 has, on the one hand, an opening angle A of 60° and, on the other hand, a gap depth B of 30 mm, which is measured from an imaginary circular path 14 of the free ends of the wings 8 up to the gap root. See in particular FIG. 8 in this regard.The one-piece fan wheel 2, which is designed as a sheet metal part, is here simultaneously designed as a bent part for realizing the vanes 8 with the air conveying elements 6. Furthermore, the sheet metal part is simultaneously designed as an embossed part for stiffening the central section 4 and the wings 8, wherein the central section 4 and the wings 8 have a single, common embossed portion 12, namely in such a way that this embossed portion 12 has a circular ring contour which spatially separates the central section 4 from the wings 8 and has radial rib contours which merge into the individual wings 8. The embossing 12 with the circular ring contour and the overall seven rib contours protrudes from the plane of the drawing of FIG. 7 in FIG. 7.The method according to the invention for producing the one-piece fan wheel according to the invention according to the present exemplary embodiment is explained in more detail below with reference to FIGS. 1 to 8.In a first step, a blank of the fan wheel 2 is produced from a one-piece sheet metal part, wherein the blank has the central section 4 and the prefabricated vanes 8 extending radially outwards from the central section 4. The prefabricated wings 8 each have, on the same side edge, a slot 16 as far as a slot root for realizing the air conveying elements 6, wherein the respective slot 16 is formed here as a notch. Furthermore, at the beginning of the method, i.e. during the production of the blank, this blank is embossed in the region of the central section 4 and in the region of the vanes 8 for the purpose of stiffening the one-piece fan wheel 2, wherein the central section 4 and the vanes 8 are embossed in a single working step, namely in such a way that the central section 4 and the vanes 8 have the single, common embossing 12. In this regard, see FIG. 1. In other embodiments of the invention, it can be provided that the above-mentioned embossing is omitted or is embodied and / or formed in another manner.After the blank of the fan wheel 2 has been produced in the aforementioned manner, in order to realize the air conveying element 6 corresponding to the respective blade 8, a part of this blade 8 is set up at an angle to a remainder of this blade 8, namely at a 90° angle to the remainder of this blade 8, wherein the aforementioned part of the respective blade 8 extends on the side with the slot 16 on the one hand from the free end of this blade 8 as far as the slot 16 and on the other hand from the side edge of this blade 8 having the slot 16 as far as the slot root. See FIG. 2.Subsequently, the respective wing 8 is bent around a bending axis 18 running along the former slot 16 in the direction of the central section 4 in such a way that a bent section of this wing 8 having the free end of this wing 8 abuts a remainder of this wing 8, wherein the air conveying element 6 corresponding to this wing 8 protrudes freely outwards from the bent section. See FIGS. 3 to 7 together.Finally, at the end of the method, the bent-over section of the respective wing 8 is connected to the rest of this wing 8 in a force-transmitting manner, wherein this force-transmitting connection is formed here as a cohesive connection, namely as a spot weld. Correspondingly, the fan wheel 2 has a total of seven welding points 20. The welding points 20 are shown in all FIGS. 1 to 7 for simplicity.In principle, however, it is conceivable in other embodiments of the invention that an aforementioned connection is either completely omitted or is effected in a different manner.FIG. 7 shows the fan wheel 2 that has been produced in the finished state.On account of the configuration according to the invention of the one-piece fan wheel 2 and the method for producing the same, on the one hand a significant weight reduction is made possible in the one-piece fan wheel 2 with at least constant flow speed of the air conveyed therewith, in comparison with the prior art, such that the energy required for a rotation of this fan wheel 2 is significantly reduced. This is advantageous in particular for the fan wheel 2 present here, which is designed as a fan wheel changing the direction of rotation, that is to say a fan wheel which can be rotated in one or the other direction of rotation depending on the operating state. The reduced mass to be rotated has proven to be advantageous both during acceleration and also during deceleration of the fan wheel 2. In comparison with the prior art, a weight reduction of approximately 25% can be realized. On the other hand, the one-piece fan wheel 2 can be produced in a very simple manner from a constructional and manufacturing standpoint by means of the method explained.However, the invention is not limited to the present embodiment. In this regard, see, for example, the statements in this regard in the introduction to the description and the alternative or optional features mentioned in the specific description section.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 3 726 930 B1

[0002]

Claims

A one-piece fan wheel (2) for an air conveying device of a domestic appliance, comprising a central portion (4) for fastening the fan wheel (2) to a shaft of the air conveying device for driving the fan wheel (2) and a plurality of air conveying elements (6) for conveying the air, wherein the air conveying elements (6) are arranged uniformly distributed over the circumference of the central portion (4) and each extend radially outwards, characterised in that the fan wheel (2) is formed as a one-piece sheet metal part and the air conveying elements (6) are each arranged on a blade (8) of the fan wheel (2), wherein the blades (8) are arranged uniformly distributed over the circumference of the central portion (4) and extend radially outwards in such a way starting from the central portion (4), that between wings (8) directly adjacent to one another, starting from free ends of these wings (8), the sheet metal part has a gap (10) extending as far as a gap root.One-piece fan wheel (2) according to Claim 1, characterized in that the sheet metal part is designed as a bent part for realizing the vanes (8) with the air conveying elements (6).One-piece fan wheel (2) according to Claim 1 or 2, characterized in that the sheet-metal part is designed as an embossed part for stiffening the central section (4) and / or the vanes (8), preferably in that the central section (4) and the vanes (8) have a single, common embossed portion (12), particularly preferably in that this embossed portion (12) has a circular-ring contour which spatially separates the central section (4) from the vanes (8) and has radial rib contours which merge into the individual vanes (8).One-piece fan wheel (2) according to one of Claims 1 to 3, characterized in that the respective gap (10) runs, starting from the free ends corresponding thereto, in a triangular manner up to the gap root of this gap (10), which is designed as a triangle tip, preferably in that this gap (10) has an opening angle (A) of 60° and / or has a gap depth (B) of 30 mm, which is measured from an imaginary circular path (14) of the free ends up to the gap root.Method for producing a one-piece fan wheel (2), according to which the one-piece fan wheel (2) is formed according to one of Claims 1 to 4.Method according to Claim 5, characterized in that the method has the following method steps in the stated sequence: - production of a blank of the fan wheel (2) from a one-piece sheet metal part, wherein the blank has the central section (4) and the prefabricated vanes (8) extending radially outwards from the central section (4), and wherein the prefabricated vanes (8) each have, on the same side edge, a slot (16) as far as a slot root for realizing the air conveying elements (6), preferably in that the respective slot (16) is designed as a notch, - for realizing the air conveying element (6) corresponding to the respective vane (8), setting up a part of this vane (8) at an angle to a remainder of this vane (8), Preferably at an angle of 90° to the rest of this wing (8), wherein the aforementioned part of the respective wing (8) on the side with the slot (16) extends on the one hand from the free end of this wing (8) as far as the slot (16) and on the other hand from the aforementioned side edge of this wing (8) as far as the slot root, - bending the respective wing (8) around a bending axis (18) running along the former slot (16) in the direction of the central section (4) such that a bent section of this wing (8) having the free end of this wing (8) abuts a rest of this wing (8), wherein the air conveying element (6) corresponding to this wing (8) protrudes freely outwards from the bent section.Method according to claim 6, characterised in that at the end of the aforementioned method the bent-over section of the respective wing (8) is connected to the rest of this wing (8) in a force-transmitting manner, preferably in that this force-transmitting connection is formed as a cohesive connection, particularly preferably in that this cohesive connection is formed as a spot weld (20).Method according to claim 6 or 7, characterised in that at the beginning of the aforementioned method the blank is embossed in the region of the central section (4) and / or in the region of the vanes (8) for the purpose of stiffening the one-piece fan wheel (2), preferably in that the central section (4) and the vanes (8) are embossed in a single working step, particularly preferably in that the central section (4) and the vanes (8) have a single, common embossing (12).

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