Method for manufacturing the rotor of an electric machine

Abstract

Method for manufacturing the rotor (6) of an electric machine, in which a rotor ring (1) is provided along its circumference with a plurality of magnets (4) spaced apart at a distance (5), wherein the magnets (4) are connected to the inside (1b) or outside (1a) of the rotor ring (1) by adhesive bonding, wherein the rotor ring (1) is brought together with a magnet positioning device (2), wherein the magnet positioning device (2) has a plurality of positioning aids (2b), wherein at least one of the magnets (4) is displaced relative to the rotor ring (1) by relative movement of the positioning aids (2b) and the rotor ring (1) while the adhesive is still uncured, wherein the relative movement between the positioning aids (2b) and the rotor ring (1) is a rotation.

Description

[0001] The invention relates to a method for manufacturing a rotor according to claim 1.

[0002] Rotors are typically manufactured by fitting a rotor ring with permanent magnets. In the case of external rotors, this is achieved by gluing permanent magnets to the inside of the rotor ring at regular intervals. During this gluing process, it is crucial that the magnets are positioned very precisely on the rotor ring to minimize the cogging torques that occur during operation. Several suggestions have been made to use low-tolerance auxiliary fixtures for this purpose. However, these fixtures have the disadvantage of complicating the process of joining the magnets to the rotor ring due to their tight tolerances.

[0003] A method for mounting permanent magnets on a rotor is known from US patent 4,586,244 A. In this patent, the magnet elements are held in clamping devices and moved relative to a rotor carrier by means of a cam or cam mechanism, so that a defined distance is established between the inner surfaces of the magnets and the rotor surface. The aim is, in particular, controlled adhesive distribution and precise radial positioning of the magnets. The alignment is achieved by mechanically moved clamps that transfer the magnet elements into a mounting position during the joining process.

[0004] DE 10 2011 011 174 A1 discloses a method for manufacturing permanent magnet rotors in which holders are movable along a common axis and magnetic elements are pressed against a rotor axis in a curing position. The magnets are moved relative to a fixing device and held in position during the curing of the adhesive.

[0005] US Patent 3,818,586 A discloses a method for mounting magnetic blocks on a rotating machine component, in which magnetic segments are positioned circumferentially and fixed using epoxy resin. Positioning is achieved using mechanical clamping and holding elements, which secure the magnetic segments in their position during curing.

[0006] From EP 1 629 586 B1, a carrier device serving as a magnet positioning device is known, which has an inner ring and radially extending retaining projections in a star shape, serving as positioning aids. The projections are spaced apart from one another and determine the relative position of the magnets held between them. To manufacture the rotor, the magnets are placed in the carrier device, then the rotor ring is fitted over them, and the carrier device, together with the magnets, is bonded to the inside of the rotor ring and remains permanently in the rotor. In this process, the carrier device, which is made of plastic in particular, thus becomes part of the finished rotor and can only be partially removed by turning the carrier device, which is bonded to the rotor ring, from the inside.

[0007] This approach is disadvantageous because components remain in the rotor that are not actually required for the operation of the rotor itself.

[0008] The object of the present invention is therefore to provide a method for manufacturing the rotor of an electric machine in which these disadvantages do not occur, any auxiliary devices such as positioning devices do not remain permanently in the rotor and yet sufficient precision can be ensured in the arrangement and connection of the magnets with the rotor ring.

[0009] This problem is solved by a method for manufacturing the rotor of an electric machine with the features of claim 1. Advantageous embodiments are found in the dependent claims.

[0010] In the inventive method for manufacturing the rotor of an electric machine, a rotor ring is provided along its circumference, depending on whether an internal or external rotor is to be manufactured, with a plurality of magnets spaced apart at intervals on the outside or inside. The magnets are bonded to the inside or outside of the rotor ring by gluing.

[0011] During the process, the rotor ring is brought together with a magnetic positioning device, which has a plurality of positioning aids. The positioning aids and the rotor ring are then moved relative to each other while the adhesive is still uncured. During this movement, the positioning aids come into contact with the magnets, so that with continued relative movement, at least one of the magnets is displaced relative to the rotor ring. Preferably, the positioning aids are spaced apart from each other according to the predetermined distances for the magnets on the rotor ring, so that during rotation between the positioning aids and the rotor ring, the magnets are each displaced along the rotor ring by exactly the distance specified by the spacing of the positioning aids.

[0012] Preferably, the magnet positioning device and the rotor ring are arranged relative to each other in such a way that gaps are formed between the rotor ring and the magnet positioning device. The magnets can then be placed in these gaps or may already be located there.

[0013] The magnets, arranged or lying in the spaces between the rings, are provisionally fixed to the rotor ring using the still-cured adhesive. This pre-fixation can be done in various ways; preferably, adhesive is applied to the magnets and / or the rotor ring at least at predetermined points before insertion.

[0014] In a particular embodiment, the magnet positioning device can be arranged concentrically with the rotor ring before the magnets are inserted. Preferably, the magnet positioning device comprises an annular section on which the positioning aids are arranged and, in particular, spaced apart from one another in the circumferential direction. In this embodiment, the magnet positioning device is designed with positioning aids projecting inwards or outwards in a star-like pattern. The positioning aids preferably form positioning projections that project radially outwards or inwards with respect to the central axis of the rotor ring, between which the spaces for receiving the magnets are formed.

[0015] If the magnets are located in the spaces between the magnets, the rotor ring is moved, in particular rotated, relative to the magnet positioning device according to the invention. A positioning aid comes into contact with an adjacent magnet and exerts pressure on it during the further course of the relative movement. This causes the magnet to be displaced relative to the rotor ring, since the adhesive has not yet fully cured.

[0016] It is sufficient for the relative movement or rotation to be only slight, so that—when the rotor ring is rotated, the flanks lying in the direction of rotation—or—when the magnet positioning device is moved or rotated, the flanks leading in the direction of rotation—of the positioning aids make contact with the magnets and can slightly displace at least one or some of them in the direction of movement or rotation. In this way, all magnets are positioned at defined distances from one another due to the virtually tolerance-free magnet positioning device. Furthermore, the gaps between them do not have to correspond exactly to the dimensions of the magnets, but can, in any case, be wider than the magnets in the direction of movement or rotation. This has the advantage that, if necessary, an existing magnet positioning device can be used for magnets of different sizes.The inventive method allows for faster production, as the magnets can be pre-assembled or pre-fixed with tolerances. The movement or rotation process then brings them into their final and precise position.

[0017] Preferably, following the positioning step described above, which is carried out by relative movement or rotation, the rotor ring equipped with the magnets and the magnet positioning device are separated from each other again.

[0018] The invention further relates to a rotor of an electric machine, in particular an external rotor, manufactured according to the method described above. The invention also further comprises an electric machine comprising such a rotor.

[0019] The invention is described below with reference to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. 8 explained in more detail. Fig. Figure 1 shows an unpopulated rotor ring. Fig. Figure 2 shows the finished workpiece fitted with magnets. Fig. Figure 3 shows an embodiment of a magnetic positioning device according to the invention. Fig. Figure 4 shows the process of bringing together the rotor ring and the magnet positioning device. Fig. Figure 5 shows the rotor ring and magnet positioning device in the assembled state. Fig. Figure 6 shows the assembly of the arrangement. Fig. 5 with magnets. Fig. Figure 7 shows the rotation process of the rotor ring relative to the magnet positioning device after the magnets have been inserted. Fig. Figure 8 shows the subsequent separation of the rotor ring and the magnet positioning device.

[0020] In the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. Section 8 describes the manufacturing process according to the invention using the example of the production of an external rotor 6 with the aid of an exemplary magnetic positioning device 2. The inventive concept is of course equally suitable for the production of internal rotors; in this case, the magnetic positioning device would be provided with radially inwardly directed positioning aids in a star shape, within which the rotor ring, to be fitted with magnets on the outside, would then be arranged.

[0021] The inventive method reduces the amount of material in Fig. 1. Rotor ring 1, shown, which has an outer surface 1a and an inner surface 1b, is fitted with magnets 4. The finished component 6 is in Fig. Figure 2 shows the magnets 4 being attached to the inside 1b of the rotor ring and are spaced 5 apart.

[0022] To produce this arrangement, a magnetic positioning device 2 is preferably used, as described in Fig. Figure 3 shows a star-shaped ring 2a with radially outwardly projecting positioning aids 2b attached to it. These positioning aids are designed as projections in the example shown and are referred to simply as "projections" below. Preferably, the ring 2a is arranged on a base 2c. Before the magnets 4 are attached to the rotor ring 1, the rotor ring 1 is placed over the magnet positioning device 2 so that the magnet positioning device 2 lies on the inside of the rotor ring 1. In the present case, see Figure 3. Fig. 4 and Fig. 5, the rotor ring 1 rests with its end face on the base 2c in the assembled state. At this point, the inner surface 1b of the rotor ring 1 may already be coated with adhesive.

[0023] In the Fig. In the situation shown in Figure 5, the mounting configuration, spaces 3 are formed between the projections 2b of the magnet positioning device 2, which are radially bounded by the inside of the rotor ring 1. These spaces 3, which are preferably all the same size and all equally spaced from each other in the circumferential direction, serve to receive the magnets 4, which, as shown in Figure 5, are arranged in the mounting configuration. Fig. As shown in Figure 6, the magnets 4 are inserted into the spaces 3 from the front face of the arrangement consisting of the magnet positioning device 2 and the rotor ring 1. The magnets 4 can be coated with adhesive on the side facing the rotor ring 1 before insertion. According to another embodiment, not shown here, it is also possible to first position the magnets 4 on the magnet positioning device and then place the rotor ring 1 over the magnet positioning device 2. Finally, it is also possible, again not shown, to first pre-fix the magnets 4 to the rotor ring 1 using adhesive and only then add the magnet positioning device 2.

[0024] After all the intended magnets 4 are positioned in the corresponding spaces 3 and pre-fixed to the rotor ring 1 – pre-fixed here meaning attached to the rotor ring with the adhesive not yet fully cured, allowing for slight movement – ​​the rotor ring 1 is rotated on the base 2c of the magnet positioning device 2 in the direction of the arrow, as shown in the example. During this rotation, the magnets 4 contact the flanks of the projections 2b of the magnet positioning device 2, so that the projections 2b form a stop for the magnets 4. The magnets 4 can therefore still be moved, at least partially, during rotation, as they are carried along by the projections.Since the magnetic positioning device 2 with the projections 2b is manufactured precisely according to specifications, all magnets 4 assume a corresponding precise target position during this rotation process, so that the positions of the magnets 4, which were still subject to tolerance when inserted into the spaces 3, have become exact positions after the rotation process.

[0025] Subsequently - especially after the adhesive has cured - the completed rotor 6 is removed from the magnet positioning device 2, see Fig. 8.

Claims

[1] Method for manufacturing the rotor (6) of an electric machine, in which a rotor ring (1) is provided along its circumference with a plurality of magnets (4) spaced apart at a distance (5), wherein the magnets (4) are connected to the inside (1b) or outside (1a) of the rotor ring (1) by adhesive bonding, wherein the rotor ring (1) is brought together with a magnet positioning device (2), wherein the magnet positioning device (2) has a plurality of positioning aids (2b), wherein at least one of the magnets (4) is displaced relative to the rotor ring (1) by relative movement of the positioning aids (2b) and the rotor ring (1) while the adhesive is still uncured, wherein the relative movement between the positioning aids (2b) and the rotor ring (1) is a rotation. [2] Method according to claim 1, wherein the magnet positioning device (2) and the rotor ring (1) are arranged relative to each other such that spaces (3) are formed between the rotor ring (1) and the magnet positioning device (2) into which the magnets (4) can be received or in which the magnets (4) are located. [3] Method according to any of the preceding claims, characterized by , that the rotor ring (1) equipped with the magnets (4) and the magnet positioning device (2) are separated from each other again after relative movement. [4] Method according to any of the preceding claims, characterized by , that the magnetic positioning device (2) comprises an annular section (2a) on which the positioning aids (2b) are arranged and, in particular, spaced apart from each other in the circumferential direction. [5] Method according to one of the preceding claims, wherein the positioning aids (2b) are positioning projections (2b) projecting radially outwards or inwards with respect to the central axis of the rotor ring (1). [6] Method according to any of the preceding claims, characterized by , that the magnet positioning device (2) is arranged concentrically with the rotor ring (1) before the magnets (4) are inserted. [7] Method according to any of the preceding claims, characterized by , that the relative movement of the rotor ring (1) relative to the magnet positioning device (2) is at least in one direction, in particular direction of rotation, such that a positioning aid (2b) comes into contact with a flank of each adjacent magnet (4) and, if necessary, the magnet (4) is thereby displaced. [8] Method according to any of the preceding claims, wherein the magnets (4) are attached to the inside of the rotor ring (1) to form an external rotor or to the outside of the rotor ring (1) to form an internal rotor. [9] Method according to any of the preceding claims, characterized by , that adhesive is applied to the rotor ring (1) and / or the magnets (4). [10] Rotor of an electric machine, in particular an external rotor, manufactured according to a method according to one of the preceding claims. [11] Electric machine comprising a rotor according to claim 10.

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