ROTOR OF AN ELECTRIC MACHINE, IN PARTICULAR OF A CLAW POLE MACHINE

Abstract

A rotor of an electric machine, in particular of a claw pole machine, has a slip ring arrangement with two slip rings which are arranged on the rotor shaft, the slip rings being placed onto an insulating sleeve which is of electrically insulating configuration and is seated directly on the rotor shaft, the insulating sleeve (59) having a thermal conductivity of at least 2 W/mK.

Claims

1. A rotor of an electric machine, in particular of a claw pole machine, having a slip ring arrangement with two slip rings, each of the slip rings being arranged on a rotor shaft of the rotor and connected via a respective busbar to a winding wire of a rotor winding, the slip rings being placed onto an insulating sleeve that is (a) made from an insulating sleeve material, (b) of electrically insulating configuration, and (c) seated directly on the rotor shaft, the insulating sleeve having a thermal conductivity of at least 2 W/mK.

2. The rotor as claimed in claim 1, the insulating sleeve material comprising a polymer.

3. The rotor as claimed in claim 2, the insulating sleeve material comprising a material mixture of polymer and a filler.

4. The rotor as claimed in claim 1, the insulating sleeve material comprising a ceramic and having a thermal conductivity of at least 170 W/mK.

5. The rotor as claimed in claim 4, the insulating sleeve material comprising a ceramic fiber composite material.

6. The rotor as claimed in claim 1, further comprising two contact tabs, each of the contact tabs being connected to a respective one of the slip rings and lying between the respective one of the slip rings and a corresponding one of the busbars.

7. The rotor as claimed in claim 6, one of the contact tabs protruding into a slot in a wall of the insulating sleeve.

8. The rotor as claimed in claim 7, the wall having a wall thickness of at most 1 mm or of at most 2 mm or of from 1.5 mm to 2.5 mm.

9. The rotor as claimed in claim 8, the rotor shaft having a shaft section configured to receive the slip rings, the shaft section forming at least one longitudinal groove extending in a longitudinal direction for receiving electric contacts of the slip rings.

10. The rotor as claimed in claim 9, the shaft section forming two longitudinal grooves spaced apart from one another, each of the longitudinal grooves being configured to receive an electric contact of a respective one of the slip rings.

11. The rotor as claimed in claim 9, further comprising, in each of the at least one longitudinal groove, plastic material overmolded at least partially on at least one of a corresponding busbar and a corresponding contact tab.

12. An electric machine, in particular a claw pole machine, having a rotor as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further advantages and expedient embodiments can be gathered from the further claims, the description of the figures and the drawings, in which:

[0019] FIG. 1 shows a perspective view of an electric machine which is used, for example, as a boost/recuperation machine in a motor vehicle,

[0020] FIG. 2 shows a section longitudinally through the machine in accordance with FIG. 1 in the region of a slip ring arrangement,

[0021] FIG. 3 shows the slip ring arrangement in section in an individual illustration,

[0022] FIG. 4 shows a perspective view of the slip rings of the slip ring arrangement including the electric contact and a partially slotted insulating sleeve,

[0023] FIG. 5 shows the slip rings with a mounted insulating sleeve,

[0024] FIG. 6 shows the slip ring arrangement including a plastic overmolding, and

[0025] FIG. 7 shows a rotor shaft which is configured for receiving the slip ring arrangement.

[0026] In the figures, identical components are provided with identical designations.

DETAILED DESCRIPTION

[0027] The electric machine 1 which is shown in FIG. 1 and in details in FIG. 2 can be used, for example, as a boost/recuperation machine in a motor vehicle and is configured as a claw pole machine. The electric machine 1 has a machine part 10 which contains the electric motor or generator, and comprises a stator 11 and an internal rotor 12 (FIG. 2). Furthermore, a brush holder 20 for the transmission of current to a rotor winding of the electric motor and power electronics 30 on the end side of the electric machine 1 belong to the electric machine 1. A connector plate 40 which connects the phases of the stator 11 to the power electronics 30 is situated between the machine part 10 and the power electronics 30. Moreover, the connector plate 40 serves to receive the brush holder 20.

[0028] The stator 11 of the machine part 10 is received between bearing plates 101 and 102 which form a housing. The stator 11 comprises a laminated core and a stator winding which is received in the laminated core. The bearing plates 101 and 102 additionally receive ball bearings, in which the rotor 12 with the rotor shaft 121 is mounted rotatably.

[0029] The transmission of current to the rotor winding of the rotor 12 takes place via a slip ring arrangement 50 and the brush holder 20 with brushes 21 and 22. The slip ring arrangement 50 comprises two sleeve-shaped slip rings 51 and 52 which, in a manner lying axially next to one another, are seated fixedly on the rotor shaft 121 so as to rotate with it, and busbars 53 and 54 and contact tabs 55 and 56. The first slip ring 51 which is arranged closer to the rotor winding is connected via the busbar 53 and the contact tab 55 to an end 57 of the winding wire of the rotor winding. Here, one end of the busbar 53 makes contact with the winding wire end 57, whereas the other end of the busbar 53 is connected to the contact tab 55, the opposite end of which is connected to the slip ring 51. In a corresponding way, the second slip ring 52 which is arranged axially further away from the rotor winding is connected via the busbar 54 and the contact tab 56 to the second winding wire end 58 of the rotor winding. The brushes 21 and 22 which are guided in the housing-side brush holder 20 lie in contact on the slip rings 51 and 52.

[0030] As shown in FIG. 2 in conjunction with FIGS. 3 to 5, the slip ring arrangement 50 comprises, moreover, an insulating sleeve 59 which consists of an electrically insulating material, but has a high thermal conductivity. For example, a polymer material or a ceramic material comes into question as a material for the insulating sleeve 59. The insulating sleeve 59 is pushed directly onto the rotor shaft 121 and is connected fixedly to the rotor shaft 121 so as to rotate with it, and is in direct contact with the circumferential face of the rotor shaft 121. The two slip rings 51 and 52 which are spaced apart axially from one another are both seated directly on the outer side of the insulating sleeve 59 and are connected fixedly to the insulating sleeve so as to rotate with it. The insulating sleeve 59 has only a comparatively small wall thickness of, for example, at most 0.5 mm or 1 mm and a thermal conductivity of at least 2 W/mK, a significantly higher thermal conductivity possibly also being possible, for example a thermal conductivity of at least 50 W/mK, at least 100 W/mK, at least 170 W/mK or even higher. Said high thermal conductivity makes an efficient thermal dissipation of the heat which is produced in the slip ring arrangement 50 via the rotor shaft 121 possible. That shaft section of the rotor shaft 121 which is a carrier of the slip ring arrangement 50 with the insulating sleeve 59 can have a comparatively great external diameter on account of the thin-walled embodiment of the insulating sleeve 59, without the overall diameter of the rotor shaft 121 and the slip ring arrangement 50 increasing in comparison with embodiments from the prior art.

[0031] A slot 60 which extends in the axial longitudinal direction is made in the insulating sleeve 59, which slot 60 extends axially only over a part length of the insulating sleeve 59 and is configured so as to be open on the edge side toward an end side of the insulating sleeve. The slot 60 in the insulating sleeve 59 allows the contact tab 56 which is assigned to the slip ring 52 to be guided through the interior space of the two slip rings 51, 52 and, in the case of a pushed-in insulating sleeve 59, to be guided radially through the slot 60, in order to establish the contact with the slip ring 52.

[0032] The further slip ring 51 is also contacted on its inner side by the associated contact tab 55.

[0033] As can be gathered from FIG. 6, the slip ring arrangement 50 has, moreover, a plastic overmolding 61, with which, in particular, the busbars 53 and 54 are overmolded. In the assembled state, the busbars 53 and 54 lie in longitudinal grooves 62 and 63 (FIG. 2, FIG. 7) which are made on opposite sides in that section of the rotor shaft 121 which is the carrier of the slip ring arrangement 50. The longitudinal grooves 62 and 63 extend beyond that section of the rotor shaft 121 which carries the slip ring arrangement 50, and extend as far as the winding wire ends of the rotor winding. The busbars 53 and 54 including the plastic overmolding 61 can possibly be received in the longitudinal grooves 62 and 63 completely in the radial direction, or can protrude radially beyond the longitudinal grooves 62 and 63.

[0034] The plastic overmolding 61 of the busbars 53 and 54 ensures the electric insulation of the busbars from the rotor shaft 121.