Rotor for an electric motor

Abstract

A rotor for an electric motor has a laminated core with a plurality of laminations, each provided with a central recess for the rotor shaft, wherein at least some of the laminations have a central recess with a non-circular cross-sectional shape. In the peripheral region of the central recess, radially widened compensating sections and radially narrowed clamping sections alternate in the circumferential direction.

Description

[0001] The invention relates to a rotor for an electric motor, having a rotor shaft and a disk pack arranged on the shaft, according to the preamble of claim 1. State of the art

[0002] DE 10 2008 004 876 A1 describes an electrical machine whose rotor comprises a rotor shaft and a lamination pack mounted on the rotor shaft, consisting of a plurality of individual laminations. Each lamination has a central recess through which the lamination is pushed onto the rotor shaft. The central recess of the lamination has a non-circular cross-sectional shape, the edge region of which comprises, in the circumferential direction, a plurality of radially expanded and radially reduced sections that differ from one another in terms of their circumferential extent, their radial extent, and their shape. This creates spring tongues in the circumferential direction that can be deflected in the axial direction. Some of the sections are designed to produce a press fit with respect to the rotor shaft. Disclosure of the invention

[0003] The rotor according to the invention can be used in electrical machines or electric motors, which are particularly designed as permanent-magnet machines with permanent magnets on the rotor side. The rotor has a rotor shaft and a lamination pack on the rotor shaft, which consists of a plurality of individual laminations arranged parallel to one another and whose plane extends perpendicular to the longitudinal axis of the rotor shaft. Each lamination has a central recess through which the lamination is pushed onto the rotor shaft.

[0004] At least some of the lamellae have a central recess with a non-circular cross-sectional shape. The edge region of the central recess has radially expanded compensating sections and radially reduced clamping sections alternating in the circumferential direction, with all compensating sections being of identical design and all clamping sections also being of identical design and thus each having the same cross-sectional shape and cross-sectional area. Furthermore, all compensating sections have the same maximum radial extent, and all clamping sections also have the same maximum radial extent. Consequently, there are only two different sections that extend alternately along the edge region of the central recess: the clamping sections and the compensating sections.

[0005] This design has several advantages. Firstly, the circumferential edge of the central recess can be easily produced by punching, and due to the small number of different sections, the tool for manufacturing and punching is correspondingly simple. In the circumferential direction, the edge area of ​​the central recess has a relatively uniform, harmonious course without any fissures. This has the advantage that stress peaks in the edge area of ​​the central recess are avoided when the laminations are pushed onto the rotor shaft. The transitions between compensating sections and clamping sections can be made continuous and harmonious, avoiding small radial indentations where there is otherwise a risk of stress peaks. The laminations can be attached particularly easily to rotor shafts with a smooth outer surface.

[0006] According to an advantageous embodiment, the compensating sections have the same or approximately the same extent in the circumferential direction as the clamping sections. Accordingly, the compensating sections extend over the same or approximately the same angular segment as the clamping sections. This embodiment also ensures a harmonious course in the circumferential direction of the boundary edge of the central recess. Particularly in the case of an oversize of the rotor shaft in relation to the central recess, i.e. a press fit, the lamina is pushed onto the rotor shaft with axial pressing force. In this case, the clamping sections are slightly bent in the axial direction and exert a clamping force on the outer surface of the rotor shaft, which fixes the lamina in its desired position on the rotor shaft.The uniform alternation of compensating sections and clamping sections in the circumferential direction allows for elastic springing of the clamping sections in the axial direction. The radially reduced clamping sections form bending beams that extend circumferentially between two adjacent compensating sections. The clamping sections are in contact with the outer surface of the rotor shaft, which can be smooth. Notches on the rotor shaft or ring caulking on the disk pack are not required. Instead, the disk pack can be pressed directly onto the rotor shaft with a smooth outer surface.

[0007] According to yet another advantageous embodiment, the clamping sections are convexly curved outward in the radial direction. This ensures that the clamping sections lie flat against the outer surface of the rotor shaft, thus ensuring flat contact between the lamina and the rotor shaft. On the one hand, a relatively high force can be transmitted between the lamina and the rotor shaft, so that the lamina is securely fixed to the rotor shaft in the axial direction and in the circumferential or rotational direction. On the other hand, the flat contact prevents force peaks.

[0008] According to a further advantageous embodiment, the maximum radial extension of the clamping sections is at least 80% to at most 95% of the maximum radial extension of the compensating sections. The clamping sections extend further radially inward accordingly, enabling a spring action that is, however, limited, so that there is no risk of excessive clamping force, which could potentially lead to damage to the rotor shaft.

[0009] It may be sufficient for only some of the laminations in the lamination pack to have a central recess with a previously described, non-circular cross-sectional shape. The remaining laminations, however, are conventionally provided with a round cross-sectional shape in the central recess. This design allows the desired pressing force and torque of the lamination pack on the rotor shaft to be variably adjusted. It is therefore sufficient to design all laminations with a central recess with a non-circular cross-sectional shape in the same way and to slide the remaining laminations with a central recess with a round cross-sectional shape onto the rotor shaft without a press fit.

[0010] According to yet another advantageous embodiment, the lamella with a non-circular cross-sectional shape of the central recess has additional recesses arranged in a ring around the central recess. These additional recesses lead to a weight reduction of the lamella. Furthermore, the radial elasticity and, if appropriate, also the axial elasticity of the lamella are increased, which makes it possible to simultaneously reduce the elasticity of the clamping sections, in particular by reducing the radial extension of the clamping sections. Alternatively, it is also possible to increase the overall elasticity by introducing the recesses.

[0011] The recesses are specifically incorporated into the lamella in such a way that the radially expanded compensating sections point between two consecutive recesses in the circumferential direction. The recesses are grouped at a radially greater distance around the central recess, with the compensating sections pointing toward the area between two consecutive recesses in the region of their maximum radius. This ensures that, despite the overall increased elasticity in the area between the central recess and the recesses grouped around it, a sufficient wall thickness is formed throughout the lamella in both the radial and circumferential directions. This reduces the risk of cracking.

[0012] According to yet another advantageous embodiment, the radial distance between the edge region of the central recess and the recesses arranged radially further outward is at most half the radius of the central recess. This ensures that the recesses are arranged at a relatively small radial distance from the central recess, thereby supporting the desired increase in elasticity.

[0013] According to yet another advantageous embodiment, the recesses have an approximately cuboid-shaped basic cross-section, with a radially outward-facing elevation arranged on the radial outer side of the cuboid-shaped basic cross-section. The recesses thus have an enlarged free cross-sectional area in the radial direction.

[0014] Advantageously, the number of clamping sections and the number of compensating sections each correspond to the number of receptacles for permanent magnets located on the outside of the lamination pack. The number of recesses can also correspond to the number of receptacles for permanent magnets. For example, if six permanent magnets are provided, each of which is attached to a receptacle on the outside of the lamination pack, the central recess in the boundary edge also has six compensating sections and six clamping sections. Six recesses can also be provided accordingly.

[0015] The invention also relates to an electric motor or an electric machine provided with a rotor as described above and a stator. The electric motor or electric machine is designed in particular as a permanently excited, electronically commutated motor.

[0016] Further advantages and practical embodiments can be found in the further claims, the description of the figures, and the drawings. They show: Fig. 1 a lamination pack for a rotor of an electrical machine, comprising a plurality of axially stacked individual laminations, each provided with a non-circular central recess, and with recesses grouped around the central recess, Fig. 2 the disc pack from Fig. 1 with an inserted rotor shaft, Fig. 3 the disk pack without rotor shaft in top view, Fig. 4 a section of the disk pack in plan view including the rotor shaft, Fig. 5 a Fig. 3 corresponding view of a slat in plan view in an enlarged representation.

[0017] In the figures, identical components are provided with identical reference symbols.

[0018] The figures show a lamination pack 1, which is part of a rotor of an electrical machine, which is designed in particular as a permanent-magnet, electronically commutated electric motor. The lamination pack 1 comprises a plurality of individual laminations 2, which are stacked one on top of the other and each designed as a sheet-metal lamination. Distributed around their outer circumference, the laminations 2 have several receptacles 3 for each accommodating a permanent magnet 4. In the exemplary embodiment, a total of six receptacles 3 and correspondingly six permanent magnets 4 are provided in the lamination pack 1.

[0019] The laminations 2 have a central recess 5 with a non-circular cross-sectional shape for accommodating a rotor shaft 6. The rotor shaft 6 is inserted into the central recess 5 with a press fit. The non-circular cross-sectional shape of the central recess 5 supports radial expansion during insertion of the rotor shaft 6. The inner, circumferential wheel area of ​​the central recess 5 is composed of compensation sections 7 and clamping sections 8, which alternate in the circumferential direction. There is the same number of compensation sections 7 and clamping sections 8 as the number of permanent magnets 4. The edge area consists exclusively of the compensation sections 7 and the clamping sections 8.

[0020] The maximum radial extent of the compensation sections 7 is greater than the maximum radial extent of the clamping sections 8. The clamping sections 8 form a kind of bridge between two adjacent compensation sections 7 and can, as in Fig. 3 with the arrows pointing radially outwards, expand radially upon insertion of the rotor shaft 6, which has an excess. Due to the greater radial extent of the compensating sections 7 compared to the clamping sections 8, the clamping sections 8 can execute a radial expansion movement with a relatively low radial force and at the same time execute an axial bending movement. After insertion of the rotor shaft 6, the radial force, which acts on the outer surface of the rotor shaft 6 due to material elasticity, acts as a clamping force, whereby the plate pack 1 is held in position on the rotor shaft 6 both axially and in the direction of rotation.

[0021] As in the Fig. 5 shown with a dashed line, the angle segments which are covered by the compensation sections 7 and the clamping sections 8 are at least approximately the same size.

[0022] The clamping sections 8 are slightly convexly curved outwards, allowing a flat contact with the outer surface of the rotor shaft 6. The compensating sections 7 do not necessarily have such a convex curvature.

[0023] At a radial distance from the central recess 5, several recesses 9 are evenly distributed around the circumference of the lamella 2. The number of recesses 9 corresponds to the number of permanent magnets 4. Each recess 9 has an approximately rectangular basic cross-section and additionally has a partially circular elevation pointing outwards on the radial outer side. The recesses 9 are grouped with respect to the compensating sections 7 and the clamping sections 8 of the central recess 5 in such a way that the radially expanded compensating sections 7 point exactly between two consecutive recesses 9 in the circumferential direction. As a result, the material thickness of the lamella 2 in the space in the radial direction and in the circumferential direction between the central recess 5 and each recess 9 is approximately the same in all positions.

[0024] In the disk pack 1, all disks 2 can be formed in the manner described above with a non-circular central recess 5. Alternatively, it is also possible for only some of the disks to be formed in this manner and for another part to be formed with a central recess with a round cross-sectional shape, which is formed either with a press fit or without a press fit with respect to the diameter of the rotor shaft. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 004 876 A1

[0002]

Claims

[1] Rotor for an electric motor, with a rotor shaft (6) and a lamination pack (1) arranged on the rotor shaft (6), consisting of a plurality of laminations (2) which have a central recess (5) for the rotor shaft (6), wherein at least some of the laminations (2) have a central recess (5) with a non-circular cross-sectional shape, characterized by that the edge region of the central recess (5) has radially expanded compensating sections (7) and radially reduced clamping sections (8) alternating in the circumferential direction, wherein all compensating sections (7) are of identical design and have the same maximum radial extent and all clamping sections are of identical design and have the same maximum radial extent. [2] Rotor according to claim 1, characterized by that the compensating sections (7) extend over the same or approximately the same angular segment as the clamping sections (8). [3] Rotor according to claim 1 or 2, characterized by that the clamping sections (8) are convexly curved outwards. [4] Rotor according to one of claims 1 to 3, characterized by that the maximum radial extension of the clamping sections (8) is at least 80% and at most 95% of the maximum radial extension of the compensating sections (7). [5] Rotor according to one of claims 1 to 4, characterized by that in the lamella pack only some of the lamellae (2) have a central recess (5) with a non-round cross-sectional shape. [6] Rotor according to one of claims 1 to 5, characterized by that a plurality of recesses (9) are made in the lamella (2) at a radial distance from the central recess (5), which are grouped in a ring around the central recess (5). [7] Rotor according to claim 6, characterized by that the radially expanded compensating sections (7) are arranged between two recesses (9) which follow one another in the circumferential direction. [8] Rotor according to claim 6 or 7, characterized by that the radial distance between the central recess (5) and the radially outer recesses (9) is at most as large as half the radius of the central recess (5). [9] Rotor according to one of claims 6 to 8, characterized by that each recess (9) has an approximately trapezoidal basic cross-section, with a radially outwardly pointing bulge being arranged on its outer side. [10] Rotor according to one of claims 1 to 9, characterized by that the number of compensating sections (7) and clamping sections (8) is the same as the number of receptacles (3) on the lamella (2) for receiving permanent magnets (4), wherein in particular the permanent magnets (4) are arranged on a radial outer side of the lamella pack (1). [11] Electric motor, with a rotor according to one of claims 1 to 10 and with a stator which has an electrical winding by means of which the rotor can be driven.

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