Rotor for an external rotor motor

Abstract

A rotor for an external rotor motor is described, comprising an annular stack (1) of welded steel sheets, permanent magnets (2) which are fastened to an inner side of the stack (1), a carrier (4) which has a hub (5) for a shaft, and clamps (3) which grip around a radially outer edge of the carrier (4) and press the carrier (4) in the axial direction against the stack (1). According to the invention, the stack (1) has pressure surfaces (6) between its axial ends, against which an end of the clamps (3) facing away from the hub (5) presses.

Description

[0001] The invention relates to a rotor for an external rotor motor, comprising an annular steel lamination stack, permanent magnets which are fastened to an inner side of the lamination stack, and a carrier which has a hub for a shaft and is fastened to the lamination stack.

[0002] The object of the present invention is to show a way in which the carrier of a rotor for an external rotor motor can be cost-effectively attached to the lamination stack.

[0003] This object is achieved by a rotor having the features recited in claim 1. Advantageous developments of the invention are the subject of subclaims.

[0004] In a rotor according to the invention, the stack of welded steel sheets is pressed axially against the support by clamps that rest on an outer side of the stack. According to the invention, the stack has pressure surfaces between its axial ends, against which an end of the clamps facing away from the support presses. Therefore, clamps that are significantly shorter than the axial length of the sheet stack can advantageously be used. The clamps of a rotor according to the invention are therefore cost-effective and allow for simple production. Each of the clamps of a rotor according to the invention can be manufactured cost-effectively as a stamped and bent part from sheet metal.

[0005] The pressure surfaces of the sheet stack against which the clamps press are preferably formed by radial projections of the sheet stack, but can also be formed by recesses and depressions on the outside of the sheet stack.

[0006] An advantageous development of the invention provides that the sheet stack is constructed from sheets of the same cut. For example, the annular sheets can have radial projections on their outer circumference, for example 3 to 6 projections. If a group of such sheets, for example 4 to 6 sheets, are stacked on top of one another in the same rotational angle position, this results in a small sheet stack with radial projections, each of which extends straight along its outer side in the axial direction. A second stack consisting of a second group of sheets can then be placed on top of this small stack, all of which are offset from the sheets of the first group by a predetermined rotational angle. Although all of the sheets in the stack thus formed are of the same design, a stack can be created which has pressure surfaces at the boundary between the first and second groups, onto which the clamps can attach.

[0007] A further advantageous development of the invention provides that the pressure surfaces are formed by axial end surfaces of radial projections of the sheet stack. These projections are preferably undercut on side surfaces extending in the axial direction, and the clamps engage in these undercuts. Such an undercut can be formed, for example, as a groove extending in the axial direction in a side surface of a projection. In this way, unintentional release of the clamps can be made more difficult.

[0008] Further details and advantages of the invention are explained using an exemplary embodiment of the invention with reference to the accompanying drawings. They show: Fig. 1 an embodiment of a rotor according to the invention; Fig. 2 a view of the rotor lamination stack; Fig. 3 a detailed view of the rotor; Fig. 4 a sectioned detailed view of the rotor; Fig. 5 another sectioned detailed view of the rotor; and Fig. 6 a view of a bracket of the rotor;

[0009] In Fig. 1 shows a rotor of an electric motor, more specifically an external rotor motor. The rotor comprises an annular lamination stack 1 made of ferromagnetic steel, for example, electrical steel sheet or other soft-magnetic steel sheet. The individual laminations of the lamination stack 1 can be annular or each form only a ring segment. Permanent magnets 2, for example, based on Nd2Fe, are attached to the inside of the lamination stack 1. 14B. The permanent magnets 2 can, for example, be arranged in grooves of the lamination stack 1 and fixed there, for example, using adhesive. The lamination stack 1 is attached to a carrier 4 with clamps 3, which has a hub 5 for a shaft. The clamps 3 grip around a radially outer edge of the carrier 4 and press the carrier 4 axially against the stack 1.

[0010] In Fig. Figure 2 shows the rotor's lamination stack 1. The laminations of the stack 1 are welded together. Between its axial ends, the lamination stack 1 has radial projections 9 on its outer side, forming contact surfaces 6 against which an end of the clamps 3 facing away from the hub 5 presses.

[0011] Fig. 3 shows a detailed view of the rotor, Fig. 4 a sectional detailed view of the rotor, with the cutting plane running along the edge of a clamp 3. Fig. 5 shows a further sectional detailed view of the rotor, with the cutting plane running through the middle of one of the clamps 3. Fig. 6 shows one of the brackets 3.

[0012] The pressure surfaces 6 are formed as axial surfaces of radial projections 9 of the sheet stack 1. As in particular Fig. As shown in Figure 4, these projections 9 are undercut in their axially extending side surfaces. In other words, the projections 9 have an undercut 11 or a recess, for example, a groove extending in the axial direction, in their side surfaces. The clamps 3 engage in this undercut 11. In this way, unwanted release of the clamps 3, particularly due to radial forces, is made more difficult. Alternatively or additionally, the clamps 3 can also be integrally bonded to the sheet stack 1, for example, by welding or gluing.

[0013] The projections 9, which form the pressure surfaces 6, can protrude laterally from ribs 8, which extend straight in the axial direction. As in particular Fig. As shown in Figure 2, the sheet stack 1 has several ribs 8 on its outer side, extending over the entire length of the sheet stack. The pressure surfaces 6 extend circumferentially from some of these ribs 8 on both sides, in the example shown from every other rib 8. The clamps 3 have a slot 10 at their end section, which presses against the pressure surfaces 6, through which the rib 8 extends.

[0014] In the illustrated embodiment, the sheet stack 1 is constructed from steel sheets that are identical within their manufacturing tolerances. These annular steel sheets each have equidistantly arranged projections on their outer circumference, for example, 4 to 10 projections. In the illustrated example, half of the projections have the width of the ribs 8, while the other half have an enlarged width, namely the width of the pressure surfaces 6.

[0015] To construct the sheet stack 1, the steel sheets are stacked in groups, with the sheets within a group being positioned at the same angle of rotation, and neighboring groups being rotated relative to each other by an angle of rotation, 45° in the example shown. The projections 9 of the neighboring groups are thus offset from each other, so that the pressure surfaces 6 at the boundary between a first and a second group are accessible to the clamps 3. The ribs 8 facilitate the correct alignment of the groups relative to each other. A group can consist of 4 to 25 sheets, for example.

[0016] As in particular Fig.5 shows, the edge of the carrier 4, around which the clamps 3 grip, can protrude in the axial direction. Radially inward from its protruding edge, the carrier 4 then has an axial recess 12 into which the respective clamp 3 engages. To further improve the adhesion of the clamps 3, a spring tab 13 can be cut out of an end section of the clamps 3, for example with a U-shaped cut line. The spring tab 13 is pressed inwards, i.e. towards the carrier 4, out of the end section. The free end of the spring tab 13 faces the edge of the carrier 4 protruding in the axial direction. The spring tab 13 thus forms a hook which prevents the clamp 3 from becoming detached.

[0017] To assemble the rotor, the lamination stack 1 is inserted into the carrier 4. The carrier 4 then rests against the outer side of the stack 1 and has axially extending slots in which the ribs 8 and the projections 9 of the lamination stack 1 are arranged. To facilitate the insertion of the lamination stack 1 into the carrier 4, these slots of the carrier 4 can narrow toward the hub 5. List of reference symbols 1 stack of sheets 2 permanent magnets 3 brackets 4 carriers 5 Hub 6 Pressure surface 8 ribs 9 lead 10 slots 11 Undercut 12 axial recess 13 spring tab

Claims

[1] Rotor for an external rotor motor, with an annular stack (1) of welded steel sheets, permanent magnets (2) which are attached to an inner side of the stack (1), a carrier (4) which has a hub (5) for a shaft, and Clamps (3) which grip around a radially outer edge of the carrier (4) and press the carrier (4) in the axial direction against the stack (1), characterized by , that the stack (1) has pressure surfaces (6) between its axial ends, against which an end of the clamps (3) facing away from the hub (5) presses. [2] Rotor according to claim 1, characterized by that the pressure surfaces (6) are surfaces of radial projections (9) of the stack (1). [3] Rotor according to claim 2, characterized bythat the projections (9) have an undercut (11) in their side surfaces extending in the axial direction and the clamps (3) engage in this undercut (11). [4] Rotor according to claim 2 or 3, characterized by that the carrier (4) rests on the outside of the stack (1) and has slots running in the axial direction in which the projections (9) of the stack (1) are arranged. [5] Rotor according to one of the preceding claims, characterized by that the stack (1) is composed of identically designed steel sheets, wherein a first group of sheets following one another in the stacking direction is offset by an angle of rotation relative to a second group of sheets following one another in the stacking direction, and thus the pressure surfaces (6) are formed at the boundary between these two groups. [6] Rotor according to one of the preceding claims, characterized bythat the carrier (4) has an axial recess (12) in the axial direction on its radially outer edge, around which the clamps (3) grip, and the clamps engage in this axial recess (12). [7] Rotor according to claim 6, characterized by that a spring tab is cut out of an end cut of the clamps (3), the free end of which faces the radially outer edge of the carrier (4). [8] Rotor according to one of the preceding claims, characterized by that the stack (1) has ribs (8) extending straight in the axial direction on a radial outer surface and the pressure surfaces (6) extend from this rib (8) in the circumferential direction. [9] Rotor according to claim 8, characterized by that the clamps (3) have a slot (10) in their end which presses against the pressure surfaces (6) through which one of the ribs (8) passes. [10] Rotor according to one of the preceding claims, characterized bythat the clamps (3) are firmly connected to the stack (1).

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