DE102016216083A1 - Fluid cooled electric machine - Google Patents

Abstract

The invention relates to a fluid-cooled electric machine (10) having a stator (12), a rotor (14) rotatably mounted within the stator (12) about an axis (A), wherein a radial one between stator (12) and rotor (14) Air gap (8) is formed. The electric machine (10) further comprises a housing (18) in which the rotor (14) and the stator (12) are accommodated and a fluid cooling device (20) with a wet space (22) formed inside the housing (18) which a cooling fluid (24) at least for wetting and cooling of the rotor (14) circulates. In this case, the rotor (14) on a front side (10a) on a first Fluidleitelement (25b-d), which deflects a radially on the rotor (14) in the direction of the stator (12) propagating cooling fluid flow (24a) from the rotor (14) and prevents it from entering the air gap (8). The arrangement is characterized in that the electric machine (10) is designed as an asynchronous machine, wherein the rotor (14) has a cage winding (15) with winding bars (16) extending axially in a laminated core (14a) and with short-circuiting rings ( 17) and wherein the first Fluidleitelement (25b-d) is formed integrally with a short-circuit ring (17).

Description

The patent application relates to a fluid-cooled electric machine according to the preamble of claim 1, as this example, already from the US 8,692,425 B2 is known.

For directed distribution of a cooling fluid in the interior of the electrical machine inside there are arranged on both faces of the rotor Fluidleitelemente in the form of Ölabweisern, which direct a radially outwardly directed spray on the rotor on winding heads of the stator winding and thereby entering cooling fluid in the radial air gap between the rotor and prevent stator largely. The oil deflectors are designed as separate elements and are fastened separately with the aid of fasteners on the rotor.

On this basis, it is an object of the present invention to reduce the variety of parts in a generic fluid-cooled electric machine and thereby represent this simpler and more cost-effective.

The above object is achieved by an electric machine with the features of claim 1. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

It is thus proposed a fluid-cooled electric machine with a stator, a rotor rotatably mounted within the stator about an axis, wherein between the stator and the rotor, a radial air gap is formed. The electric machine further comprises a housing, in which the rotor and the stator are accommodated, and a fluid cooling device with a wet space formed inside the housing, in which a cooling fluid circulates at least for wetting and cooling the rotor. In this case, the rotor has on one end face a first fluid guide element, which deflects a radially on the rotor in the direction of the stator propagating cooling fluid flow from the rotor and prevents it from penetrating into the air gap.

According to the invention, it is proposed to design the electrical machine as an asynchronous machine, wherein the rotor has a cage winding with winding bars running axially in a laminated core and with short-circuit rings arranged on the end side thereof, and wherein the first fluid-conducting element is formed integrally with a short-circuiting ring.

Due to the intended design of the Fluidleitelements this is now formed as an integral region of the shorting ring, which keeps away from radially inward radially outward on the rotor fluid flow from entering the air gap and this optionally deflects in a different direction. A remote fluid can already be done by a radial overlap of the air gap by a short-circuit ring, to which only a correspondingly executed radial collar is to be provided, which is preferably at least slightly radially overlapping arranged to the stator lamination.

In this way, the Kurschlussringe next to their electrical function can take over a Fluidleitfunktion when cooling the rotor. The modification of the short-circuit rings may in particular be accompanied by an enlargement of the cross-section, thereby increasing the electrically effective cross-section and reducing the electrical resistance. The cross-sectional enlargement can be carried out so that in this case also a surface to be wetted by a cooling fluid is increased, thereby enabling a more effective removal of heat loss from the rotor. In addition, by the one-piece design of a short-circuit ring with a Fluidleitelement the heat dissipation obstructing interfaces, so that now an improved heat dissipation from the heat source, ie the winding bars and the laminated core of the rotor is achieved, which leads to an increase in efficiency and performance of the electric machine ,

To achieve a particular axial deflection of the fluid flow from the inlet region of the air gap, the fluid guide can be formed as an axial extension of the short-circuit ring. Alternatively, as already mentioned, a radial extension can also be provided which radially bridges the air gap.

According to an advantageous variant, a short-circuit ring may be formed at least in common with a one-piece fluid-conducting element as a cast part made of an aluminum or a copper material, in particular also as a cast part falling from the mold. According to a further development, the winding rods and the short-circuit rings provided on both sides of the rotor can be formed with the fluid-conducting elements as a common casting.

Such a proposed axial extension or radial extension is easy to produce by casting. To counteract the Coanda effect, the casting radii can be removed at the outer diameter regions of the axial processes, for example by small grooves.

According to an advantageous development, a second fluid guide element can be provided, which is arranged stationarily relative to the stator and which forms together with the first Fluidleitelement a Fluidleitstruktur, in particular a seal assembly to prevent ingress of fluid into the air gap. The second fluid guide element can be provided as a separate element and can be fixed directly or indirectly on the stator or on the housing of the electrical machine. Alternatively, the second fluid guide can also be integrally formed with a housing wall of the electric machine. The second fluid guide element can have openings for the passage of the fluid circulating in the interior of the machine. Alternatively, this can also be designed to be fluid-tight, so that the winding heads of the stator winding are not detected directly by the interior cooling and can optionally be cooled by a separate cooling circuit and possibly also with another cooling medium.

The invention will be described by way of example with reference to the attached FIGURE. This shows a fluid-cooled asynchronous machine with sections (a) - (d), which differ in particular in the design of the short-circuit ring.

The figure shows in its entirety a schematic representation of a fluid-cooled electric machine 10 , in particular an asynchronous internal-rotor machine with a stator 12 and with one inside the stator 12 Rotor rotatably mounted about an axis A. 14 where between stator 12 and rotor 14 a radial air gap 8th is trained. Next is a housing 18 provided in which the rotor 14 and the stator 12 are included. The electric machine includes a fluid cooling device 20 with one inside the case 18 trained wet room 22 in which a cooling fluid 24 at least for wetting and cooling of the rotor 14 circulates as indicated by the arrows. The inlet of cooling fluid into the wet room 22 or machine interior takes place through outflow openings 26a in a rotor shaft designed as a hollow shaft 26 while the outlet of the cooling fluid via a in a cylindrical housing part 18a or in a bearing plate 18b of the housing 18 provided drain openings 18c he follows.

Conventionally, in the case of the asynchronous machine 10 both the rotor 14 as well as the stator 12 each laminated cores 12a . 14a , where the stator 12 with a stator winding 13 and the rotor 14 with a short circuit winding 15 or cage winding are executed which axially in grooves of the rotor laminated core 14a extending winding bars 16 and on both sides of the front side arranged thereon shorting rings 17 having which the winding bars 16 on the front sides 10a , b of the machine 10 electrically connect together in the circumferential direction. In the present embodiment, the winding bars 16 and the shorting rings 17 as a materially coherent area by means of a die-casting process made of an aluminum material. Alternatively, the short-circuit rings 17 also as separate elements on the winding bars 16 be deferred.

For the following explanations, the asynchronous machine 10 divided into four sub-areas (a) - (d), which with respect to the targeted adjustment of a flow of the cooling fluid 24 with regard to the design of the short-circuit rings 17 differ. The division made is for illustrative purposes only. It is understandable that due to the rotational symmetry of rotor 14 and stator 12 about the axis of rotation A a, in a partial area (a) - (d) respectively shown embodiment at least on one end face 10a or 10b or on both ends 10a , b of rotor 14 and stator 12 can be realized.

In section (a), the cooling fluid 24 initially radially out of the rotor shaft 26 exit and move along the rotor 14 in the direction of the stator 12 and the stator winding 13 , in particular spread on the end windings. In this case, a certain proportion of the cooling fluid 24 in the air gap 8th occur, which on the one hand to unwanted drag losses of the electric machine 10 lead and on the other hand, the cooling fluid 24 , in particular thermally degrade and destroy a cooling oil.

To prevent the entry of cooling fluid 24 in the air gap 8th points the rotor 14 , as this is exemplified by the partial regions (b) - (d), at the end faces 10a . 10b in each case a first, one-piece with a short-circuit ring 17 formed fluid guide 25b -D up. In particular, the short-circuit ring 17 and the respective fluid guiding element 25b -D jointly formed as a casting, which applies here to all embodiments.

As can be seen, the fluid guide element 25b in section (b) as an axial extension 17b on the short-circuit ring 17 formed and has radially outwardly rising or opening conical surface areas. This will be a radially inward on the extension 17b impinging cooling fluid flow in both the radial and axial directions of the rotor 14 distracted or rejected. Furthermore, a second fluid guide element 19b provided, which is stationary to the stator 12 is arranged and which together with the first fluid guide 25b a Fluidleitstruktur 32b , in particular a sealing arrangement 32b to prevent fluid from entering the air gap 8th formed. The second fluid guide 19b is as one between the case 18 and the stator 12 inserted and the axis A enclosing annular cap preferably made of a plastic, wherein an open bottom area provided on this axially and optionally also radially overlapping to the extension 25b is arranged. A radially over the extension 25b spreading cooling fluid flow is thus through the second fluid guide 19b from the air gap 8th kept away and can thus in the range of the bearing plate 18b flow back and through the drain opening provided there 18c the electric machine 10 leave.

The exemplary embodiment illustrated in subsection (c) is based on the above explanations for subsection (b) and merely represents a modification, with only differences being named below. Here it is on the short-circuit ring 17 provided extension 17c for forming the fluid guide element 25c executed with cylindrical surfaces and the second fluid guide 19c is only fixed on the stator. Also by this, compared to the portion (b) modified embodiment, the cooling fluid 24 sure of a penetration into the air gap 8th be held.

In the embodiment shown with partial area (d) is on the short-circuit ring 17 now a radial extension 17d for forming the fluid guide element 25d executed. The extension 17d bridges the air gap 8th and is also close to the winding head of the stator winding located there 13 introduced, so that a remaining at this position entrance gap between the rotor 14 and stator 12 as small as possible. Again, if necessary, a second annular fluid guide 19d be provided, which, as in the other embodiments, but not mandatory. In the present case, in the partial region (d), a U-shaped ring is used for this purpose, which is connected to a radial leg on the end shield 18b and with a cylindrical portion on the winding head 13 supports and wherein another leg of the extension 25d axially engages behind and overlaps this radially. For the passage of the cooling fluid 24 in the direction of the drainage holes 18c are in the fluid guide 19d provided corresponding through holes.

Basically, in the treated embodiments of the sub-areas (a) - (d), the position of the inlet and outlet openings 18c . 26a the cooling fluid, the embodiment of the second fluid guide elements 19 independent of the configuration of the first Fluidleitelements 25 to see so that a total of numerous, also not specifically addressed combinations are possible and open up to the expert.

It is of course also possible to provide on a short-circuit ring both axially and radially extending extension.

LIST OF REFERENCE NUMBERS

(A) - (d)

 subregion

8th

air gap

10

electric machine

10a, b

 front

12

stator

12a

stator lamination

13

stator

14

rotor

14a

Laminated core

15

Short circuit winding

16

winding bar

17

Shorting ring

17b-d

 extension

18

casing

18a, b

 end shield

18c

drain hole

20

Fluid cooling system

22

wet room

24

cooling fluid

25b-d

 fluid guide

26

rotor shaft

26a

outflow

32b-d

 sealing arrangement

A

axis of rotation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The 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

• US 8692425 B2 [0001]

Claims (4)

Fluid cooled electric machine ( 10 ), comprising - a stator ( 12 ), - one within the stator ( 12 ) about an axis (A) rotatably mounted rotor ( 14 ), whereby between stator ( 12 ) and rotor ( 14 ) a radial air gap ( 8th ), - a housing ( 18 ), in which the rotor ( 14 ) and the stator ( 12 ) and - a fluid cooling device ( 20 ) with one inside the housing ( 18 ) trained wet room ( 22 ), in which a cooling fluid ( 24 ) at least for wetting and cooling of the rotor ( 14 ), wherein - the rotor ( 14 ) on a front side ( 10a ) a first fluid guide element ( 25b -D) which extends radially on the rotor ( 14 ) in the direction of the stator ( 12 ) spreading cooling fluid flow ( 24a ) from the rotor ( 14 ) and at an entrance into the air gap ( 8th ), characterized in that - the electric machine ( 10 ) is designed as an asynchronous machine, wherein - the rotor ( 14 ) a cage winding ( 15 ) with axially in a laminated core ( 14a ) extending winding bars ( 16 ) and with short-circuit rings arranged on the end side ( 17 ) and wherein - the first fluid guide element ( 25b -D) in one piece with a short-circuit ring ( 17 ) is trained. Fluid cooled electric machine 10 according to claim 1, characterized in that the first fluid guiding element ( 25b D) as an axial extension ( 17b , c) or as a radial extension ( 17d ) on the short-circuit ring ( 17 ) is trained. Fluid cooled electric machine 10 according to claim 1 or 2, characterized in that a short-circuit ring ( 17 ) at least with the first fluid guiding element ( 25 ) is formed jointly as a casting. Fluid cooled electric machine 10 according to one of claims 1-3, characterized in that a second fluid guiding element ( 19b D) which is stationary with respect to the stator ( 12 ) is arranged and which together with the first Fluidleitelement ( 25b D) a fluid conducting structure ( 32b -D), in particular a sealing arrangement for preventing the penetration of cooling fluid ( 24 ) in the air gap ( 8th ) trains.

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