Rotor and method for positioning magnets of a rotor

Abstract

Rotor (1) for an electric motor, in particular a circulating pump, with a rotor assembly (2) mountable on a shaft (3), on which several pockets (7) are formed around the circumference, into each of which a magnet (4) is inserted, wherein at least one recess (5) is provided in the inner wall of each pocket (7), wherein a dimensionally stable clamping element (6) is inserted into the recess (5), which clamps the respective magnet (4) outwards against the rotor assembly (2) to fix the respective magnet (4) in the pocket (7), wherein the clamping elements (6) are designed as crimping pins formed from a soft metallic wire whose tensile strength is less than 300 N / mm² 2 lies.

Description

[0001] The present invention relates to a rotor according to the preamble of claim 1 and a method for positioning magnets of a rotor.

[0002] In conventional rotors, the magnets are usually glued to the outside of the rotor or into its pockets to provide a permanent connection between the rotor and the permanent magnets. It is important to position the magnets in a defined manner to minimize any imbalance that may occur during operation. The magnets must also be protected against mechanical damage. One known way to do this is to overmold the magnets with a plastic. However, overmold the rotors with externally mounted magnets is a cost-intensive method of protecting against mechanical damage.

[0003] DE 10 2007 015 249 A1 discloses a rotor with permanent magnets in which each pocket of the rotor core is provided with at least one groove extending parallel to the shaft, into which an element for securing the respective magnet in the pocket is inserted. Securing the magnets in this way has proven effective in practice, but is not suitable for the production of rotors for large series, where a cost-optimized solution is increasingly desired.

[0004] From WO 2007 / 004009 A2, it is known to use spring steel stirrups as elements. Spring steel has a high hardness and a tensile strength of more than 1000 N / mm 2 , it can therefore damage the magnets when inserted into the grooves.

[0005] Fastening elements are shown in the documents DE 10 2005 060 119 A1, JP S59- 21 266 A, JP H10- 126 986 A, JP 2000- 69 709 A, JP 2000- 184 638 A, JP 2008- 199 831 A and JP 2001- 339 885 A. Further state of the art is shown in the documents JP 2000- 341 920 A, JP 2004- 357 418 A and JP 2003- 299 280 A. The caulking of workpieces is known to the public, for example, from the Wikipedia article Caulking in the archived version from January 11, 2009.

[0006] The object of the present invention is therefore to create a rotor which is of simple construction, ensures an exact fixation of the magnets on the rotor package and can be produced cost-effectively.

[0007] It is a further object of the present invention to provide a method for simple and cost-effective positioning of magnets of a rotor.

[0008] These objects are achieved with a rotor having the features of claim 1, as well as a method for positioning magnets of a rotor having the features of claim 10.

[0009] According to the invention, the elements are designed as caulking elements or, alternatively, as elastomer elements. Using such elements allows for very easy placement of the elements in the recesses provided. The method according to the invention enables short cycle times for fastening the magnets. This fastening method is therefore an ideal solution for large-scale production.

[0010] Advantageous embodiments of the invention are the subject of the subclaims.

[0011] According to a preferred embodiment of the invention, the elements are designed as caulking pins. These can be easily inserted into the recesses provided for this purpose and then caulked. Another advantage is that manufacturing tolerances of the components in question can be compensated for by this type of magnetic fixation.

[0012] According to another preferred embodiment of the invention, the magnets are additionally glued in the pocket. This provides additional security with regard to the service life of the motor. Furthermore, this type of fastening eliminates the need for the previously used end plates on the front sides of the rotor core.

[0013] The invention will be explained in more detail below using an exemplary embodiment with reference to the accompanying drawings. They show: Fig. 1 a cross section through an embodiment of a rotor, Fig. 2 a sectional view through the Fig. 1 cutting surface marked B - B, Fig. 3 a sectional view through the Fig. 1 section surface marked A - A (longitudinal section), Fig. 4 a detailed view of the Fig. 3 section marked C, Fig. 5 a feeding and caulking machine.

[0014] As in the Fig. 1 and Fig. As can be seen in Figure 3, a rotor 1 for a permanent magnet motor, in particular for an electric motor, comprises a circulating pump, a rotor assembly 2 through which a shaft 3 is guided. The shaft 3 can be stepped and connected to a gear or driven component.

[0015] In the rotor package 2, as shown in Fig. 1, four pockets 7 are cut out, into each of which a magnet 4, preferably a permanent magnet, in particular a rare earth magnet, is inserted with play. The magnet 4 has approximately the same width as the rotor core 2 and is held in position in the pockets 7. For this purpose, a recess 5 is provided on each long side of the pockets 7, into each of which a dimensionally stable element 6 is inserted, which presses the respective magnet 4 outwards against the rotor core 2 in a clamping manner. Instead of the central arrangement of the recess 5 shown, it can also be provided laterally.

[0016] As in the Fig. 2 to 4, the element 6 is preferably designed as a caulking pin, which, after being inserted into the recess 5, is caulked in the recess 5 by means of a caulking tool 8 and thereby presses the respective magnet 4 outwards against the rotor core 2. By caulking with the caulking tool 8, the caulking pins, which are preferably made of a soft metallic wire with a tensile strength of less than 300 N / mm 2 consist of a shape changed so that the initial diameter D A of the respective caulking pin to a caulking pin with a larger final diameter D E Copper with a tensile strength of approximately 200 N / mm 2 . Aluminium or a tin alloy with tensile strengths below 100 N / mm 2Although they are more malleable, they tend to flow and thus to lose the contact pressure and are therefore only possible to a limited extent. The corresponding permissible final dimension for the caulking was determined in advance. The cut wire pieces for caulking the magnets 4 can be fed via a feeding and caulking machine 10 (see Fig. 5) can be easily placed in rotor 2.

[0017] In a further embodiment, the magnets and / or the elements 6 are additionally glued in the pocket 7. This bonding can be achieved either by applying a small amount of an adhesive, preferably a liquid adhesive that solidifies after a certain time, to the caulked wire, or by completely filling the gap between the magnet 4 and the inner wall of the respective pocket 7, which is provided with the recess 5, with an adhesive.

[0018] After the elements 6 have been inserted into the designated recesses 5 and caulked, a pressure force is exerted on the magnets 4. This pressure is preferably in the range of 80 to 150 Newtons required to remove the unbonded magnets 4, ensuring sufficient pressure for at least 20 years.

[0019] To position the magnets in a rotor, the magnets 4 are first inserted into the respective pockets 7. Subsequently, the elements 6 designed as caulking elements are placed in the respective recess 5 and caulked there using the automatic feeding and caulking machine 10. This compresses the elements 6 to a predetermined dimension, which, in the case of the elements designed as caulking pins, leads to a partial enlargement of the diameter of the caulking pins, thus securing the magnets in the respective pockets.

[0020] Preferably, in a further method step, the elements 6 and / or the magnets 4 are at least partially wetted with an adhesive, so that the magnets are thereby permanently fixed in the rotor.

Claims

[1] Rotor (1) for an electric motor, in particular a circulating pump, with a rotor package (2) which can be mounted on a shaft (3), on which a plurality of pockets (7) are formed circumferentially, into each of which a magnet (4) is inserted, wherein at least one recess (5) is provided in the inner wall of each pocket (7), wherein a dimensionally stable clamping element (6) which presses the respective magnet (4) outwards against the rotor package (2) in a clamping manner is inserted into the recess (5) for fixing the respective magnet (4) in the pocket (7), wherein the clamping elements (6) are designed as caulking pins which are formed from a soft metallic wire whose tensile strength is below 300 N / mm 2 lies. [2] Rotor according to claim 1, characterized by that the metallic wire is a copper wire. [3] Rotor according to claim 1, characterized by that the metallic wire is an aluminum wire. [4] Rotor according to claim 1, characterized bythat the metallic wire is made of a tin alloy. [5] Rotor according to one of claims 1 to 4, characterized by that the magnets (4) are glued into the pocket (7). [6] Rotor according to claim 5, characterized by that the clamping elements (6) are glued in the pocket (7). [7] Rotor according to one of claims 1 to 6, characterized by that each of the magnets (4) in the clamped state is pressed with an outer surface against an inner side of the pocket (7), which is opposite the inner wall of the respective pocket (7) provided with the recess (5), and a gap is formed between the inner wall of the respective pocket (7) provided with the recess (5) and the respective magnet (4). [8] Rotor according to claim 7, characterized by that the gap is at least partially filled with an adhesive. [9] Rotor according to one of claims 1 to 8, characterized bythat the pressure force exerted by the clamping elements (6) on the magnets (4) is of a magnitude which requires a force of 80 to 150 Newtons to pull out the magnets (4). [10] Method for positioning magnets (4) of a rotor according to one of the preceding claims 1 to 9, comprising the method steps: • Insert the magnets (4) into the respective pocket (7), • Place the clamping elements (6) in the recess (5), • Caulking the clamping elements (6), whereby they are compressed to a predetermined extent, which leads to a partial enlargement of the diameter of the clamping elements (6) and thus a fixation of the magnets (4) in the respective pockets (7) is achieved. [11] Method according to claim 10, comprising the further method step: • At least partially wetting the clamping elements (6) with an adhesive.

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