Electric machine

Abstract

An electric machine comprising a housing (1), a stator (2), and a rotor (3), the rotor shaft (4) of which is rotatably mounted on the housing (1) by means of a bearing (5). The rotor (3) is axially divided into rotor sections (6), between which the bearing (5) is arranged.

Description

[0001] The present invention relates to an electric machine.

[0002] From DE2748550 A1, an electric machine is known, comprising a housing, a stator, and a rotor, the rotor shaft of which is rotatably mounted on the housing. A ball bearing is arranged on each of the bearing shields, via which the rotor shaft is supported.

[0003] The number of components in an electric machine and the effort required to assemble them influence the manufacturing costs. The task was to design an electric machine whose manufacturing costs could be reduced.

[0004] According to the invention, this problem was solved by the electric machine according to claim 1. Advantageous further developments are specified in the dependent claims.

[0005] The electric machine is equipped with a housing, a stator, and a rotor, the rotor shaft of which is rotatably mounted to the housing by means of a bearing. The bearing can be a rolling bearing. Unlike known electric machines, the rotor is axially divided into rotor sections, between which the bearing is arranged. In this way, it is possible to save one bearing point, so that the rotor is supported at a single bearing point on the housing.

[0006] This bearing forms a central bearing, eliminating the need for additional bearing points. This central bearing is preferably designed as a rolling bearing capable of absorbing radial and axial forces.

[0007] Depending on the application, it may be advantageous for the central bearing to also be able to transmit tilting moments.

[0008] Eliminating an additional bearing reduces both assembly effort and the number of components. The central bearing arrangement and, for example, the symmetrical arrangement of the rotor relative to both axial sides of the bearing allow for a shorter axial design of the electric machine. The mechanical variation of the air gap between the rotor and stator can be reduced.

[0009] Advantageous applications of this electric machine are found in steering systems of motor vehicles, for example in actuators for rear axle steering.

[0010] The bearing point can be balanced in the axial direction of the rotor so that the tilting moments acting on the bearing are minimized during operation of the electric machine. For example, the rotor parts on both sides of the bearing can be identical and have the same axial distance to the bearing axis.

[0011] The housing of the electric machine can include a central section that has a bearing seat for receiving the bearing and axial through-holes. The central section acts as a bearing shield and is arranged axially between the housing shields. The bearing seat itself can be designed in a known manner. The axial through-holes enable rigid and lightweight housings.

[0012] The stator can be divided into axially arranged stator parts, which are arranged on both sides of the central part and whose stator parts have common stator coils, the stator windings of which are passed through the through-holes of the central part.

[0013] The disc-shaped central section can have star-shaped webs arranged around the rotor axis, between which the through-openings are located. These central sections can be made of cast aluminum.

[0014] The rotor shaft can be a plug-in component passing through the rotor parts and the bearing. The rotor shaft penetrates one of the two bearing shields and its free end can be connected to a gearbox, for example.

[0015] The rotor parts arranged axially to both sides of the central part can each be equipped with permanent magnets distributed around the circumference.

[0016] The bearing can be designed as a rolling bearing, whose rolling elements roll on raceways of bearing parts, one of which is supported on the housing side and the other on the rotor side.

[0017] For low-power electric machines, a single-row deep groove ball bearing can be suitable as a central bearing, which can be designed as a four-point bearing.

[0018] For higher power outputs, it may be advantageous to use a double-row deep groove ball bearing.

[0019] The invention is explained in more detail below with reference to an embodiment illustrated in three figures. These show: Fig. 1. Schematic representation of a longitudinal section through an electric machine, Fig. 2 a housing of the electric machine from figure in perspective view, Fig. 3 a wound stator of the electric machine Fig. 1 in perspective representation, and Fig. 4 a bearing of the electric machine

[0020] The in the Fig. The electric machine shown in Figures 1 to 3 has a housing 1 in which a stator 2 and a rotor 3 are accommodated. A rotor shaft 4 is rotatably mounted on the housing 1 by means of a bearing 5. The rotor 3 is axially divided into rotor sections 6, between which the bearing 5 is arranged. This single bearing 5 forms a central bearing 7.

[0021] Of the shields 8, 9 of the housing 1 arranged at both axial ends of the electric machine, only the one in the Fig. 1 Shield 8 shown on the left is provided with a shaft passage 10 through which the rotor shaft 4 is passed, which is connected with its free end protruding from the housing 1 to a gearbox not shown.

[0022] The housing 1 has a central part 11 with a bearing seat 25 for receiving the central bearing 7. The central part 11 is approximately disc-shaped and is rigidly connected at its outer circumference to a housing shell 12 of the housing 1. The central part 11 and the housing shell 12 are each made of an aluminum casting material and can be manufactured together in one piece.

[0023] The stator 2 is divided into two axially arranged stator parts 13, which are arranged on both sides of the central part 11 and whose stator parts 13 have common stator coils 14.

[0024] Stator windings 15 of the common stator coils 14 are passed through through openings 16 of the central part 11.

[0025] The through-openings 16 are circumferentially bounded by webs 17 of the central part 11, which are arranged radially around the bearing axis and are rigidly connected radially outward to the housing shell 12. At their radially inward ends, the webs 17 are rigidly connected to a cylindrical bushing 18. This cylindrical bushing 18 can be part of the central part 11 and integrally connected to the webs 17. The cylindrical bushing 18 forms the bearing seat 25 for the central bearing 7. The Fig. It can be seen from Figure 1 that the bearing point 26 for the central bearing 7 is arranged in the axial direction centrally between the two identical rotor parts 6.

[0026] Fig. Figure 3 clearly shows the large number of stator coils distributed around the circumference 14.

[0027] The rotor parts 6, arranged axially to both sides of the central part 11, each carry permanent magnets 27 distributed around their circumference.

[0028] The central bearing 7 is designed as a rolling bearing 19, which in the exemplary embodiment is characterized in detail by a Fig. The deep groove ball bearing 20 shown in Figure 4 is formed by its rolling elements 22, designed as balls 21, which roll on raceways 29 of bearing parts 23. These bearing parts 23 can be formed by an outer ring 24 and an inner ring 28. The outer ring 24 is inserted into the cylindrical bushing 18 of the central part 11 of the housing 1. The inner ring 28 is mounted on the rotor shaft 4.

[0029] Depending on the size of the electric machine, double-row ball bearings or four-point ball bearings may be suitable.

[0030] The rotor shaft 4 is inserted as a plug-in part through the rotor parts 6 and through the central bearing 7. Reference symbol list 1 case 2 Stator 3 Rotor 4 Rotor shaft 5 bearings 6 Rotor part 7 Central warehouses 8 sign 9 sign 10 Shaft feedthrough 11 Middle section 12 Housing shell 13 Stator part 14 Stator coil 15 Stator winding 16 Passage opening 17 Bridge 18 Cylinder bushing 19 rolling bearings 20 radial groove ball bearings 21 balls 22 rolling elements 23 Bearing part 24 outer ring 25 bearing seat 26 storage location 27 Permanent magnet 28 inner ring 29 career QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 2748550 A1

[0002]

Claims

[1] Electrical machine, with a housing (1), and with a stator (2) and with a rotor (3), the rotor shaft (4) of which is rotatably mounted on the housing (1) by means of a bearing (5), characterized by that the rotor (3) is axially divided into rotor parts (6), between which the bearing (5) is arranged. [2] Electrical machine according to claim 1, the bearing point (26) of which is balanced in the axial direction of the rotor (3). [3] Electrical machine according to one of claims 1 or 2, the housing (1) of which comprises a central part (11) which has a bearing seat (25) for receiving the bearing (5) and axial through-openings (16). [4] Electrical machine according to claim 3, the stator (2) of which is divided into stator parts (13) arranged axially one behind the other, which are arranged on both sides of the central part (11) and whose stator parts (13) have common stator coils (14), the stator windings (15) of which are passed through the through openings (16) of the central part (11). [5] Electrical machine according to claim 4, the disc-shaped central part (11) of which has webs (17) arranged in a star shape around the rotor axis, between which the through openings (16) are formed. [6] Electrical machine according to one of claims 1 to 5, whose rotor shaft (4) is passed through the rotor parts (6) and the bearing (5) as a plug-in part. [7] Electrical machine according to one of claims 1 to 6, whose rotor parts (6) arranged axially on both sides of the central part (11) are each provided with permanent magnets (27) distributed over the circumference. [8] Electrical machine according to one of claims 1 to 7, the bearing (5) of which is designed as a rolling bearing (19), the rolling elements (22) of which roll on raceways (29) of bearing parts (23), of which one bearing part (23) is supported on the housing side and of which the other bearing part (23) is supported on the rotor side. [9] Electrical machine according to one of claims 2 to 8, whose central part (11) is formed from an aluminum material.

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