CN110739806A

CN110739806A - Electric machine

Info

Publication number: CN110739806A
Application number: CN201910646394.0A
Authority: CN
Inventors: 安德烈亚斯·霍奇; 本杰明·克莱恩; 贝恩德·施罗德
Original assignee: SEG Automotive Germany GmbH
Current assignee: SEG Automotive Germany GmbH
Priority date: 2018-07-19
Filing date: 2019-07-17
Publication date: 2020-01-31
Also published as: DE102018117499A1

Abstract

electric machine having a current transfer system for transferring current to a rotor winding (57), comprising stator-side brushes (21, 22) in brush holders and having stator-side current contact elements (51, 52) against which the brushes rest in contact, wherein a cooling path is provided in the rotor along the rotor-side current contact elements, wherein at least stator-side air guide elements (23) are provided in the cooling path for deflecting and increasing the volume flow and/or the flow rate of cooling air (71).

Description

Electric machine

Technical Field

The invention relates to an electric machine, for example a claw-pole machine, with a current transfer system for transferring current to the rotor windings according to the preamble of claim 1.

Background

DE 3838436 a1 describes a claw-pole machine, the rotor of which has a slip ring assembly with two axially adjacent slip rings, via which an excitation current can be transmitted to the field winding of the rotor, brushes are in sliding contact with the slip rings, and the slip rings are each connected to the ends of the field winding of the rotor via a busbar.

Disclosure of Invention

According to the invention, electric machines having the features of claim 1 are proposed, advantageous embodiments being the subject matter of the dependent claims and the subsequent description.

The electrical machine according to the invention is, for example, a claw-pole machine with rotor windings, wherein the current transfer system comprises two axially adjacent slip rings on the rotor shaft of the rotor, wherein slip rings are each in sliding contact with a brush which is arranged in the stator or in the housing of the electrical machine.

The electrical machine can also have a plurality of rotor windings, if necessary, and a rectifier system for transmitting and rectifying the current to the rotor windings. In this case, the current transmission system is formed by a rectifier system which comprises a rotor-side collector against which brushes which transmit the current bear and are in sliding contact. The current collector has a plurality of laminations distributed along the circumference, which respectively form the rotor-side current contact elements of the current transmission system and are connected to the rotor winding.

Due to the sliding contact between the brushes and the current contact elements on the rotor side, heat is generated, which is dissipated along a cooling path in the rotor. The cooling path runs along the rotor-side current contact element and serves for guiding cooling air, which is preferably moved along the cooling path by means of a rotor-side fan. The fan is usually connected to the rotor and performs the same rotational movement as the rotor shaft of the rotor.

In order to influence the cooling air movement, at least air guiding elements are provided on the cooling path, which are arranged on the stator side or on the housing side, and serve to divert and increase the volume flow of the cooling air flowing through the cooling path, preferably two air guiding elements are also present on the cooling path, at least air guiding elements are directly or indirectly fixedly connected to the stator or the housing of the electrical machine, improved effective heat dissipation is achieved by increasing the volume flow, which is guided along the rotor-side current contact elements, in particular in the contact regions between the current contact elements and the brushes, at least air guiding elements, which are arranged fixedly with the stator or the housing, lead to an increased flow rate of the cooling air and/or to an increased volume flow of the cooling air, and also to a targeted guidance and diversion of the cooling air to the rotor-side current contact elements and brushes.

At least air guiding members may preferably be configured as sectors or sections of e.g. a funnel-shaped, conical, cylindrical or ring-shaped hollow mould which open in the axial direction, i.e. in the direction of the rotor axis.

However, hollow molds, in particular funnel-shaped, conical, cylindrical or annular, which completely surround the rotor shaft and are open in the axial direction are also possible.

The air guiding component may thus completely or partially surround the rotor shaft. In the case of a sector, this advantageously extends over an angle of between 90 ° and 270 °, preferably between 90 ° and 180 °, particularly preferably 180 ° (i.e. is, for example, of half-open design).

If the air guide element is designed as a fan, this preferably also extends over an angle of at most 180 °, but it can also be advantageous if fan sections are provided which extend over an angle between 180 ° and less than 360 °.

According to , at least or of these air-guiding components located on the cooling path are arranged on a brush holder which receives or more brushes, wherein the brushes are held in the brush holder towards the assigned current contact component and are guided in a radially displaceable manner (with reference to the rotor axis).

The air-guiding part is preferably arranged adjacent to an end of the brush-holder, which end faces the current-contacting part on the rotor side.

The outer side faces preferably project beyond the side walls of the brush holder and can be used for mounting on a housing component. The inner side face preferably forms an inclined flow face which extends in the direction of the cooling path and forms a wall which delimits the cooling path. The volume flow of cooling air flows along the inner side with a flow vector which is oriented more or less parallel to the inner side. The air guiding element configured in this way supports and improves the air flow along the current contact element on the rotor side.

If necessary, it can be advantageous for the inner side of the air guiding element to partially surround the nearest current contact element. If the air guiding elements are configured as sectors of a hollow mould with an angle of between 90 ° and 270 °, preferably between 90 ° and 180 °, particularly preferably 180 °, i.e. preferably configured half-openly, the inner side preferably forms the open side of the current contact element facing the rotor side. In this way a compact design can be achieved which at the same time supports the flow guidance.

According to another , at least or of the air-conducting elements located in the cooling path are arranged on a housing wall of a connecting plate, by means of which the stator windings in the stator are connected to the power electronics.

The housing projection is adjacent to the current contact element on the rotor side and reduces the free flow cross-sectional area of the cooling path, which leads to an acceleration of the flow of the cooling air and to an increase of the volumetric flow of the cooling air, the housing projection can extend over an angle of, for example, at least 180 ° and accordingly reduces the free flow cross-sectional area of the cooling path in the region adjacent to the current contact element on the rotor side within this angle range.

In the case of the design of the electrical machine as a claw-pole machine, it can be advantageous if the housing projection extends annularly through an angular range , which is interrupted only by the brush holder.

If two air guide members are present, they may preferably comprise two of the aforementioned air guide members, namely an air guide member arranged on the brush-holder and an air guide member configured as a housing projection. It is also advantageous if the two air guiding elements are arranged opposite each other with reference to the rotor axis and/or each partially enclose the rotor shaft.

The air-guiding elements on the brush holder and on the housing wall of the connecting plate can alternatively or cumulatively be present.

Drawings

Further advantages and advantageous embodiments can be derived from the further claims, the description of the figures and the figures.

FIG. 1 is a perspective view of an electric machine, such as used as a power recovery motor in an automobile;

FIG. 2 is a cross-sectional view of the machine according to FIG. 1 in the area of a slip ring assembly;

FIG. 3 is a perspective view of a brush-holder formed with an air guide member;

fig. 4 is a view corresponding to fig. 2 of a machine of the variant with an air-guiding member in the form of a housing projection.

In these drawings, like elements are labeled with like reference numerals.

Detailed Description

The electric machine 1 shown in fig. 1 and partially in fig. 2 can be used, for example, as a power-assisted recovery motor in a motor vehicle (i.e., can be operated both as an electric motor and as an electric generator) and is designed as a claw-pole machine, the electric machine 1 has a machine part 10 which contains an electric motor or a motor and comprises a stator or stator 11 and an internally located rotor 12 (fig. 2), furthermore, a brush holder 20, which is part of an electrical current transmission system for transmitting an electrical current to the rotor windings of the electric motor, and power electronics 30 at the end face of the electric machine 1, a connection plate 40 is located between the machine part 10 and the power electronics 30, which connection plate connects the phases of the windings of the stator 11 to the power electronics 30, and the connection plate 40 serves, in addition, to accommodate the brush holder 20.

The stator 11 of the machine part 10 is received between bearing end caps 101 and 102 forming a housing. The stator 11 comprises a lamination stack and stator windings received in the lamination stack. The bearing caps 101 and 102 additionally receive ball bearings, on which the rotor 12 with the rotor shaft 121 is rotatably supported.

The slip ring assembly 50 comprises two rotor-side current contact elements, which are designed as sleeve-shaped slip rings 51 and 52 and which are axially fixed in a rotationally fixed manner on the rotor shaft 121, and bus bars for electrical connection to the winding wire ends of the rotor windings, which bus bars connect the winding wire ends 57 to the slip rings 51, the

brushes

21 and 22 are arranged in contact on the slip rings 51 and 52, which brushes are guided in the housing-side brush holders 20, bus bars 53 are shown in fig. 2 and 4, which bus bars connect the winding wire ends 57 to the slip rings 51, the bus bars and the slip rings 51 and 52 are accommodated in the plastic injection molding 61, and two connections for electrical connection of the

brushes

21 and 22 are provided at the end of the brush holder 20 opposite the air-guiding element 23, to the rotor windings of the rotor 12.

In order to determine the angular position of the rotor shaft 121, a rotation angle sensor 80 is arranged adjacent to the end side of the rotor shaft 121, wherein the rotation angle sensor 80 has a permanent magnet 82 in a housing part 81, and the housing part 81 is connected in a rotationally fixed manner to the rotor shaft 121 by means of a fixing pin 83, for example by means of a press fit.

The slip ring assembly 50 is enclosed by a housing wall 41 of the connecting plate 40, wherein a receiving space or slip ring space 70 is formed in the interior of the housing wall 41, which receives the slip ring assembly 50. The receiving or slip ring chamber 70 is flowed through by cooling air 71, which is conveyed in a volumetric flow by a rotor-side fan 122 through the receiving or slip ring chamber 70. Adjacent to the brush-holder 20, the cooling air enters the receiving or slip-ring chamber 70, is conveyed along the slip-ring assembly 50 with the two slip rings 51 and 52 and flows along the channel defined by the housing wall 41 of the connecting plate 40 toward the fan 122, from which it is discharged from the electrical machine. This ensures that the heat generated in the current transmission system due to the friction between the

brushes

21, 22 and the slip rings 51, 52 is effectively dissipated.

To improve the cooling, an air guide element 23, which is shown in an enlarged view in fig. 3, is provided on the brush holder 20, which air guide element 23 is formed in one piece with the brush holder 20 and is designed as a semi-open conical or funnel-shaped sector, which is arranged adjacent to the end of the brush holder 20, at which the

brushes

21 and 22 project, the funnel outer side 24 forms a support surface for supporting on the housing component, the funnel inner side 25 forms ramps, along which the cooling air 71 can flow, wherein the cooling air flows parallel to the direction of inclination of the funnel inner side 25, the direction of inclination of the funnel inner side 25 is designed in such that the cooling air 71 reaches the slip rings 51 and 52 directly and the ends of the

brushes

21 and 22, the funnel-shaped air guide element 23 extends along an angular region of approximately 180 °, as can be seen from fig. 3.

Fig. 4 shows a further exemplary embodiment of the rotor 12, which is largely identical in construction to the rotor of fig. 2, fig. 4 also shows air guide elements 23 in the form of funnel sectors, which assist the air flow of the slip ring assembly 50 and lead to an increased volumetric flow of cooling air, on the brush holder 20, in addition, further air guide elements 42 are provided on the cooling path of the cooling air 71, which are formed on the housing wall 41 in the form of housing projections which reduce the free flow cross-sectional area in the receiving or slip ring chamber 70, thereby achieving a significant increase in the flow rate of the cooling air 71, the housing projections 42 are part of the housing wall 41 and advantageously extend in a part-circular or part-cylindrical manner around the slip rings 51 and 52 between the circumferential end sides of the brush holder 20, so that a part-circular receiving or slip ring chamber 70 with a reduced free flow cross-sectional area is formed in each case, the increased flow rate or increased volumetric flow of the cooling air 71 further improves the heat dissipation step .

Claims

electric machine, in particular claw-pole machine, with a current transfer system for transferring current to a rotor winding of a rotor (12), wherein the current transfer system has stator-side brushes (21, 22) in a brush holder (20) and has rotor-side current contact parts (51, 52) against which the brushes (21, 22) rest in contact, wherein a cooling path (70) is provided in the rotor (12) along the rotor-side current contact parts (51, 52) of the current transfer system, characterized in that at least stator-side air guide parts (23, 42) are provided in the cooling path for diverting and increasing the volume flow and/or flow rate of cooling air (71) guided through the cooling path (70).
2. The electric machine according to claim 1, characterized in that the at least air guiding parts (23, 42) are configured as sectors of a hollow mould, in particular funnel-shaped, cone-shaped, cylindrical or ring-shaped, which is open in the axial direction.
3. An electric machine as claimed in claim 2, characterized in that the sectors extend over an angle of between 90 ° and 270 °, preferably between 90 ° and 180 °, particularly preferably 180 °.
4. The electric machine according to claim 1, characterised in that the at least air-guiding parts (23, 42) are funnel-shaped or cone-shaped.
5. An electric machine as claimed in claim 3 or 4, characterized in that the inner side (25) of the at least air-guiding members (23, 42) partly encloses the current contact members (51, 52).
6. An electric machine as claimed in claim 3 or 4, characterized in that the inner side (25) of the at least air guiding members (23, 42) partly surrounds the rotor shaft.
7. The electric machine according to claim 1, characterized in that the at least air guiding members (23) are arranged on the brush-holder (20).
8. An electric machine as claimed in claim 1, characterized in that the electric machine (1) has a connection plate (40) for electrically contacting the windings, the at least air-guiding members (42) being arranged on a housing wall (41) of the connection plate (40).
9. The electric machine according to claim 8, characterized in that the at least air guiding members (42) on the connection plate (40) are configured as housing projections (42) on the housing wall (41), wherein the housing projections (42) are arranged adjacent to the rotor-side current contact members (51, 52) and reduce the free flow cross-sectional area of the cooling path (70).
10. The electric machine according to claim 8 or 9, characterized in that the housing wall (41) of the connection plate (40) defines the cooling path (70).
11. An electric machine as claimed in claim 1, characterized in that there are two stator-side air guide elements (23, 42) on the cooling path.
12. An electric machine as claimed in claim 11, characterized in that the two air guide members are arranged opposite each other with reference to the rotor axis.
13. An electric machine as claimed in claim 1, characterized in that the rotor-side current contact part of the current transfer system comprises two axially side-by-side slip rings (51, 52) on a rotor shaft (121) of the rotor (12).
14. An electric machine as claimed in claim 1, characterized in that the rotor-side current contact part of the current transmission system is configured as a current collector which rotates with a rotor shaft (121) of the rotor (12).
15. The electrical machine according to claim 1, characterized in that there is a rotor-side fan (122) for generating a volume flow of the cooling air (71).