Method for manufacturing a rotor unit for an electric motor blower for a household appliance and rotor unit

Abstract

The invention relates to a method for manufacturing a rotor unit (2) for an electric motor blower of a household appliance, wherein a rotor shaft (4) of the rotor unit (2) with two rolling bearings (8) of the rotor unit (2) arranged spaced apart from each other on the rotor shaft (4) along a rotor axis (6) of the rotor shaft (4) is inserted into an injection mold and, using a plurality of slides (10) of the injection mold, is overmolded with plastic to form a motor housing of the rotor unit (2) for the subsequent receipt of at least a part of an electric motor of the electric motor blower, to form a bearing seat (14) for receiving outer rings (16) of the rolling bearings (8) and to form a spacer element (18) between inner rings (17) of the rolling bearings (8). Furthermore, the invention relates to a rotor unit (2) for an electric motor blower of a household appliance.

Description

[0001] The invention relates to a method for manufacturing a rotor unit for an electric motor blower for a household appliance and a rotor unit for an electric motor blower for a household appliance.

[0002] Methods for manufacturing a rotor unit for an electric blower for a household appliance, and rotor units for electric blowers for household appliances, are already known in the art in a multitude of embodiments. For example, in electric blowers, a pair of deep groove ball bearings is frequently used to support the rotor shaft of the rotor unit. This bearing is preloaded by sliding the inner and outer rings. Such a bearing arrangement is also referred to as a preloaded bearing arrangement. This allows for regulation of the running clearance and particularly tight guidance. The inner and outer rings of the two aforementioned bearings are generally held in their intended position by frictional engagement using an interference fit or adhesive bond and / or by positive engagement using shoulders on the shaft or in the housing.The preload is typically applied using a spring element that bears against the bearing rings and the housing. Arrangements are known in which the bearings are supported directly in the motor housing, as well as bearing arrangements in which the preloaded bearing assembly, a so-called bearing cartridge, is inserted into a housing as a pre-assembled unit. In both cases, it is necessary to precisely adjust the positions of the bearing rings and the relative position of the inner and outer rings during manufacturing, either through the form and position tolerances of the individual parts or using a fixture, to ensure that the specified preload is maintained exactly. Therefore, high precision of the individual parts and / or a complex manufacturing process are required to produce a high-quality and thus durable bearing. This results in high component costs and / or high equipment costs for its production.Furthermore, the spring elements required for preloading the bearing are often not needed during operation of the motors, as both bearings are designed as fixed bearings, for example.

[0003] The invention thus addresses the problem of improving a method for manufacturing a rotor unit for an electric motor blower for a household appliance and a rotor unit for an electric motor blower for a household appliance.

[0004] According to the invention, this problem is solved by a method with the features of claim 1. Furthermore, this problem is solved by a rotor unit with the features of claim 8. Advantageous embodiments and further developments of the invention are described in the following dependent claims.

[0005] The advantage achievable with the invention lies particularly in the fact that a method for manufacturing a rotor unit for an electric motor fan for a household appliance and a rotor unit for an electric motor fan for a household appliance are improved. Due to the inventive design of the method for manufacturing a rotor unit for an electric motor fan for a household appliance and the rotor unit for an electric motor fan for a household appliance, the manufacturing of the rotor unit is significantly simplified, and at the same time, a rotor unit that is functionally at least equivalent to the prior art is provided. Firstly, the number of process steps in the manufacturing process according to the invention is reduced. Secondly, the number of components in the rotor unit according to the invention is also reduced without restricting its function.Furthermore, the components can be designed at least in part more simply and their manufacture requires less precision than with the state of the art.

[0006] In principle, the rotor unit according to the invention for an electric motor blower of a household appliance, as well as the inventive method for its manufacture, can be freely selected within wide suitable limits. Thus, the rotor unit according to the invention and the method for its manufacture can be adapted to a large number of household appliances and therefore to a wide range of suitable electric motor blowers. For example, the household appliances could be vacuum cleaners or the like. Of course, the invention is not limited to household appliances, but can also be advantageously used in appliances for professional use, i.e., commercial appliances. Accordingly, the rotor unit according to the invention can be suitably designed in many ways, for example, with regard to type, function, material, and dimensions.

[0007] A particularly advantageous embodiment of the inventive method provides that the two rolling bearings are permanently preloaded against each other by means of the aforementioned manufacturing of the rotor unit using the slides; preferably, the inner rings of the rolling bearings are moved outwards along the rotor axis into their final position relative to the rotor shaft by means of the slides, and the outer rings of the rolling bearings are moved inwards along the rotor axis into their final position relative to the rotor shaft by means of the slides; particularly preferably, the outer rings of the rolling bearings are moved along the rotor axis by means of spring-loaded inserts of the injection mold. In this way, regulation of the running clearance and particularly tight guidance are possible. Such a bearing arrangement is also referred to as a preloaded bearing arrangement.The preferred embodiment of this further development provides a particularly suitable and structurally simple and robust technical solution. Furthermore, the particularly preferred embodiment of this further development is very well adapted to the conditions of injection molds.

[0008] Accordingly, a particularly advantageous further development of the rotor unit according to the invention provides that the two rolling bearings are permanently preloaded against each other only by means of the aforementioned manufacture of the rotor unit, preferably that the two rolling bearings are each designed as a deep groove ball bearing.

[0009] A further advantageous embodiment of the method according to the invention provides that the injection mold has two mold halves that are movable relative to each other. Preferably, a closing direction of the injection mold for moving the two mold halves into a closed position of the injection mold runs parallel to the rotor axis, and the slides are moved perpendicular to the rotor axis. Particularly preferably, the spring-loaded inserts of the injection mold are arranged on both mold halves. This makes the method particularly well-suited to the requirements of injection molding. This applies especially to the preferred and, in particular, to the especially preferred embodiment of this embodiment.

[0010] Another advantageous embodiment of the method according to the invention provides that the majority of the slides comprise three slides, preferably that the majority of the slides comprise a total of three slides. In this way, the majority of the slides comprise a number of individual slides that is particularly suitable for the present application of the injection mold. With the preferred embodiment of this embodiment, a very advantageous compromise is achieved in terms of design, manufacturing, and cost.

[0011] Furthermore, an advantageous embodiment of the inventive method provides that the method is suitable for a rotor shaft without steps, preferably a continuously ground rotor shaft. This significantly simplifies the design and manufacture of the rotor shaft and thus makes it much more cost-effective.

[0012] Accordingly, an advantageous further development of the rotor unit according to the invention provides that the rotor shaft is designed without steps, preferably as a continuously ground rotor shaft.

[0013] A further advantageous embodiment of the inventive method provides that the distance between the two rolling bearings along the rotor axis is undersized by a maximum of the total bearing clearance of the bearing arrangement formed by the two rolling bearings. This further simplifies the manufacturing of the inventive rotor unit using the injection mold. For example, the total bearing clearance, i.e., the sum of the bearing clearances of the two rolling bearings, can be twice the bearing clearance of each of the two rolling bearings.

[0014] Another advantageous embodiment of the inventive method provides that the spacer element is produced by means of channels formed in the slides. This significantly simplifies the supply of the liquid plastic for the production of the spacer element during the injection molding process, i.e., during the production of the rotor unit according to the inventive method.

[0015] An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows Fig. 1 An embodiment of the inventive method for manufacturing the rotor unit according to the invention in a first perspective, partial view, Fig. 2 the embodiment in a second perspective, partial view, Fig. 3 the embodiment in a third perspective, partial view, Fig. 4 the embodiment in a fourth perspective, partial view, Fig. 5 the embodiment in a first partial longitudinal section view, Fig. 6 the embodiment in a second partial longitudinal section view, Fig. 7 the rotor unit of the exemplary embodiment in a longitudinal section view and Fig. 8 the rotor unit of the exemplary embodiment in a perspective view.

[0016] In the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Figure 6 shows an exemplary embodiment of the inventive method for manufacturing the rotor unit according to the invention. The rotor unit manufactured in this way is described in the following sections. Fig. 7 and Fig. Figure 8 shows that the rotor unit 2 is designed to be suitable for an electric motor blower of a household vacuum cleaner. However, other household appliances and electric motor blowers designed specifically for them with rotor units according to the invention are also conceivable. Accordingly, the term "blower" is to be interpreted broadly, so that, for example, all types of fans or the like are also included.

[0017] The method for manufacturing the rotor unit 2 for the electric motor blower of the household appliance designed as a vacuum cleaner (not shown in detail) involves inserting a rotor shaft 4 of the rotor unit 2, with two roller bearings 8 of the rotor unit 2 arranged spaced apart from each other on the rotor shaft 4 along a rotor axis 6 of the rotor shaft 4 and each designed as a deep groove ball bearing, into an injection mold (only partially shown). Using a plurality of slides 10 of the injection mold, the rotor unit 2 is then overmolded with plastic to form a motor housing 12 for the subsequent accommodation of at least part of an electric motor (not shown) of the electric motor blower, to form a bearing seat 14 for receiving outer rings 16 of the roller bearings 8, and to form a spacer element 18 between inner rings 17 of the roller bearings 8.The method is suitable here for a rotor shaft 4 without steps, namely a continuously ground rotor shaft 4. In the present embodiment, the distance between the two rolling bearings 8 along the rotor axis 6 is undersized by a maximum of the total bearing clearance of the bearing arrangement formed by the two rolling bearings 8. Since the two rolling bearings 8 are identical to each other, the total bearing clearance here corresponds to twice the bearing clearance of one of the two rolling bearings 8.

[0018] The two rolling bearings 8 are permanently preloaded against each other by means of the aforementioned manufacturing of the rotor unit 2 using the slides 10, whereby the inner rings 17 of the rolling bearings 8 are displaced outwards along the rotor axis 6 into their final position relative to the rotor shaft 4 by means of the slides 10, and the outer rings 16 of the rolling bearings 8 are displaced inwards along the rotor axis 6 into their final position relative to the rotor shaft 4 by means of the slides 10, namely such that the outer rings 16 of the rolling bearings 8 are moved along the rotor axis 6 by means of spring-loaded inserts of the injection mold (not shown). As can be seen from the Fig. 2, Fig. 3 to Fig. 4 is removable, the majority of the slides 10 have a total of three slides 10, wherein the spacer element 18 is produced by means of channels 20 formed in the slides 10.

[0019] Furthermore, the injection mold has two mold halves that are movable relative to each other, wherein a closing direction of the injection mold for moving the two mold halves into a closed position of the injection mold runs parallel to the rotor axis 6 and the slides 10 are moved perpendicular to the rotor axis 6, and wherein the spring-loaded inserts of the injection mold are arranged on both mold halves. The two mold halves of the injection mold with the spring-loaded inserts are also not shown.

[0020] The following describes the inventive method for manufacturing the rotor unit according to the present embodiment with reference to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 explained in more detail.

[0021] As described above, the motor shaft, i.e., the rotor shaft 4, is manufactured without steps and is ground throughout. The two roller bearings 8, designed as deep groove ball bearings, are pre-assembled onto the rotor shaft 4 to the required dimensions. The bearing distance between the two roller bearings 8 is adjusted so that it is at most twice the bearing clearance of one of the two roller bearings 8 too small. The rotor shaft 4 with the roller bearings 8 is then inserted into the plastic injection mold, i.e., the injection mold for plastic injection molding. The injection mold is then moved from its open position to its closed position, with the closing direction of the injection mold being parallel to the motor shaft axis, i.e., the rotor axis 6. After the injection mold has closed, the three slides 10, which move perpendicular to the rotor axis 6, are moved within the injection mold in the direction of the rotor axis 6.The slides 10 are designed such that they run onto the outer rings 16 and the inner rings 17 of the two rolling bearings 8 and move the inner rings 17 towards the free ends of the rotor shaft 4 into their respective final positions relative to the rotor shaft 4. The two rolling bearings 8 have the desired final bearing distance on the inner ring side. During the aforementioned movement of the rolling bearings 8, the rotor shaft 4 is supported in the mold halves of the injection mold. The respective height dimension of the slides 10 corresponds exactly to the aforementioned desired distance of the inner rings 17 of the rolling bearings 8. The surfaces of the slides 10 parallel to the direction of movement are designed such that the outer rings 16 of the rolling bearings 8 can move sufficiently along the rotor axis 6 to achieve the necessary preload of the rolling bearings 8.This displacement of the outer rings 16 is achieved by means of the spring-loaded inserts of the two mold halves of the injection mold, which now move in the closing direction of the injection mold, i.e., along the rotor axis 6, from the outside to the inside. This is in the . Fig. 6 with arrows 22 symbolized. While the outer rings 16 of the two rolling bearings 8 in the Fig. 5 are each arranged at a height with the corresponding inner ring 17 of the respective rolling bearing 8, as shown by the Fig. 6 the height of the respective outer ring 16 in its final position along the rotor axis 6 relative to the rotor shaft 4, i.e., with the rolling bearings 8 preloaded against each other. In the following, the cavity formed in the manner described above is filled with plastic by means of an injection molding process. This process produces, on the one hand, the motor housing with the receptacles for the bearing rings, namely the bearing seats 14 for the outer rings 16 of the rolling bearings 8, and on the other hand, the spacer element 18 on the rotor shaft 4. The spacer element 18 is precisely bounded by the inner rings 17 of the rolling bearings 8. This spacer element is formed with plastic via the channels 20 in the slides 10. After the required curing of the plastic in the injection mold, the slides 10 are retracted, and on the other hand, the two mold halves of the injection mold are moved apart again, i.e., the injection mold is returned from its closed position to its open position.

[0022] The rotor unit 2, manufactured in the aforementioned manner, can be removed from the injection mold. The rotor unit 2 is in the Fig. 7 and Fig. 8 shown. As can be seen in particular from a review of the Fig. 7 and Fig. As can be seen in Figure 8, the bearing seats 14 of the outer rings 16 of the rolling bearings 8 have recessed areas in the form of rounded indentations.

[0023] Due to the inventive design of the method for manufacturing the rotor unit 2 for an electric blower for a household appliance and the rotor unit 2 itself, the manufacturing of the rotor unit 2 is significantly simplified, and at the same time, a rotor unit 2 that is functionally at least equivalent to the prior art is provided. Firstly, the number of process steps in the described manufacturing process is reduced. Secondly, the number of components in the rotor unit 2 is also reduced without restricting its function. Furthermore, the components of the rotor unit 2 can be designed, at least in part, more simply, and their manufacture requires less precision than in the prior art.

[0024] However, the invention is not limited to the present embodiment. See in particular the relevant explanations in the introductory section.

Claims

[1] Method for manufacturing a rotor unit (2) for an electric motor blower of a household appliance, wherein a rotor shaft (4) of the rotor unit (2) with two rolling bearings (8) of the rotor unit (2) arranged spaced apart from each other on the rotor shaft (4) along a rotor axis (6) of the rotor shaft (4) is placed in an injection mold and is overmolded with plastic using a plurality of slides (10) of the injection mold to form a motor housing of the rotor unit (2) for subsequently receiving at least a part of an electric motor of the electric motor blower, to form a bearing seat (14) for receiving outer rings (16) of the rolling bearings (8) and to form a spacer element (18) between inner rings (17) of the rolling bearings (8). [2] Method according to claim 1, characterized by, that the two rolling bearings (8) are permanently preloaded against each other by means of the aforementioned manufacture of the rotor unit (2) using the slides (10), preferably that the inner rings (17) of the rolling bearings (8) are moved outwards along the rotor axis (6) into their final position relative to the rotor shaft (4) by means of the slides (10) and that the outer rings (16) of the rolling bearings (8) are moved inwards along the rotor axis (6) into their final position relative to the rotor shaft (4) by means of the slides (10), particularly preferably that the outer rings (16) of the rolling bearings (8) are moved along the rotor axis (6) by means of spring-loaded inserts of the injection molding tool. [3] Method according to claim 1 or 2, characterized bythat the injection mold has two mold halves that are movable relative to each other, preferably that a closing direction of the injection mold for transferring the two mold halves into a closed position of the injection mold runs parallel to the rotor axis (6) and the slides (10) are moved perpendicular to the rotor axis (6), particularly preferably that the spring-loaded inserts of the injection mold are arranged on both mold halves. [4] Method according to any one of claims 1 to 3, characterized by , that the majority of the slides (10) has three slides (10), preferably that the majority of the slides (10) comprise a total of three slides (10). [5] Method according to any one of claims 1 to 4, characterized by , that the method is suitably designed for a rotor shaft (4) without steps, preferably a continuously ground rotor shaft (4). [6] Method according to any one of claims 1 to 5, characterized by, that the distance between the two rolling bearings (8) along the rotor axis (6) is undersized by a maximum of the total bearing clearance of the bearing arrangement formed from the two rolling bearings (8). [7] Method according to any one of claims 1 to 6, characterized by , that the spacer element (18) is produced by means of channels (20) formed in the slides (10). [8] Rotor unit (2) for an electric motor blower of a household appliance, wherein the rotor unit (2) is designed as a plastic-encased rotor shaft (4) with rolling bearings (8) spaced apart from each other along a rotor axis (6) of the rotor shaft (4), and wherein a motor housing of the rotor unit (2) for subsequently receiving at least a part of an electric motor of the electric motor blower, bearing seats (14) for receiving outer rings (16) of the rolling bearings (8) and a spacer element (18) arranged between inner rings (17) of the rolling bearings (8) are formed solely by means of the aforementioned plastic overmolding. [9] Rotor unit (2) according to claim 8, characterized by that the two rolling bearings (8) are permanently preloaded against each other only by means of the aforementioned manufacture of the rotor unit (2), preferably that the two rolling bearings (8) are each designed as a deep groove ball bearing. [10] Rotor unit (2) according to claim 8 or 9, characterized by , that the rotor shaft (4) is designed without steps, preferably as a continuously ground rotor shaft (4).

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