DE102018218820A1 - Electrical machine with a fluid cooling device - Google Patents

Abstract

An electrical machine (1) with a stator (4), a rotor (7) and with a fluid cooling device (15) is described. The rotor (7) is mounted to the stator (4) by means of a rotor shaft (10) and a bearing (13) arranged on a bearing plate (11). The fluid cooling device (15) has a cooling tube (16) which is fixed to a carrier element (17), is in fluid communication with a fluid inlet (18) and a fluid outlet (19) and which is located within a recess (10a) Rotor shaft (10) and with the formation of an annular space (10b). Between the rotor shaft (10) and the carrier element (17) there is a sealing area (20) with a sealing element (21) which essentially transfers fluid into a space area (22) of the electrical machine (1) lying outside the sealing area (20) prevented. The sealing element (21) comprises a first section (23a) which is fixed to the carrier element (17) and a second section (23b) which is fixed to the rotor shaft (10). The second section (23b) of the sealing element (21) has an outer diameter which is smaller than an inner diameter of the first bearing (13). The bearing (13) has a sealing arrangement (13c) on the axial side facing the sealing element (21), by means of which a bearing interior (13f) is sealed against the ingress of cooling fluid.

Description

The invention relates to an electrical machine with a fluid cooling device according to the preamble of claim 1, as already with the WO 2016/050534 A1 has become known. To cool the rotor of the electrical machine described there, a cooling tube is axially inserted into a section of a rotor shaft designed as a hollow shaft, through which a cooling fluid can flow into an annular space between the latter and the rotor shaft and can absorb heat loss from the rotor. The coolant can flow in and out on the same end face of the electrical machine, as a result of which only a sealing element between the rotating rotor and the fixed elements of the machine is required.

The object of the invention is to further improve such a generic electrical machine with a fluid cooling device.

The above object is achieved by an electrical machine with the features specified in claim 1. Advantageous refinements and developments of the invention can be found in the dependent claims and the following description of the figures.

Within the scope of the present invention, an electrical machine with a fluid cooling device is proposed, which first comprises a stator with a stator lamination stack and with a stator winding and a rotor with a rotor lamination stack, which rotates by means of a rotor shaft and a first bearing arranged on a first bearing plate an axis is rotatably mounted to the stator. The fluid cooling device has a cooling tube which is fixed to a stator-fixed support element of the electrical machine and which is connected to a fluid inlet and which extends axially within a central recess in the rotor shaft and forms an annular space to the rotor shaft. The cooling tube is in fluid connection with the annular space and with a fluid outlet at the same time. Furthermore, a sealing area with a sealing element is provided between the rotor shaft and the carrier element, which at least substantially prevents fluid transfer into a space area of the electrical machine that is outside the sealing area when a cooling fluid flows through from the fluid inlet to the fluid outlet. The sealing element comprises a first section which is fixed to the carrier element and further comprises a second section which is fixed to the rotor shaft and which is in sealing connection with the first section.

According to the invention, it is provided in the electrical machine that the second section of the sealing element has an outer diameter which is smaller than an inner diameter of the first bearing. Furthermore, the first bearing itself has, at least on the axial side facing the mechanical seal, a sealing arrangement acting between a radially inner and a radially outer bearing ring, by means of which a bearing interior is sealed, inter alia, against the ingress of cooling fluid.

The proposed solution has the advantage that further sealing elements or corresponding measures can be dispensed with in a space between the sealing element directly exposed to the flow of the cooling fluid and the first bearing, in particular as a result of the sealing arrangement provided as part of the first bearing. This has the further advantage that the electrical machine can be made axially shorter and the installation space gained can be used for other purposes.

A particularly space-saving arrangement can be achieved in that the second section of the sealing element is at least partially axially overlapping to the first bearing. In this way, the axial length of the electrical machine can be shortened again.

In order to achieve the best possible sealing effect, the sealing element can advantageously be designed as a mechanical seal, in particular as an axial mechanical seal and in particular as a Levitex seal from Carl Freudenberg KG. A Levitex seal is a gas-lubricated mechanical seal, which is used in particular to seal the annular gap between an oil-filled crankcase and a crankshaft of an internal combustion engine. An effective diameter of the sealing surfaces involved can thus be kept comparatively small. An axial overlap of the mechanical seal with the first bearing can also take place within a comparatively small installation space. This means that the first bearing can also be designed with a correspondingly small outer diameter.

In a further embodiment, the first bearing can have a sealing arrangement on both axial sides in order to improve the sealing effect. The interior of the bearing can be filled with a pasty lubricant, in particular with a high-speed grease. The interior of the bearing can be protected against the ingress of cooling fluid and against the escape of lubricant by the sealing arrangement.

For a noticeable increase in the fluid-cooled inner circumferential surface of the rotor shaft and Thus, for the purpose of further improving the cooling effect, an inner diameter of the rotor shaft or the central recess there can be made larger in the area of an axial extension of the rotor laminated core than in the area of the first bearing.

The invention is explained below by way of example using an embodiment shown in the figures.

• 1 eine als Fahrzeugachsantrieb ausgebildete elektrische Maschine mit einer Fluid-Kühleinrichtung in einer Axialschnittdarstellung;
• 2 ein vergrößerter Ausschnitt der Fluid-Kühleinrichtung von 1 im Bereich eines Lagerschildes der elektrischen Maschine;
• 3 eine perspektivische Darstellung der elektrischen Maschine im Bereich des Lagerschilds von 3;
• 4 eine perspektivische Ansicht eines an einem Gehäuse der elektrischen Maschine ausgebildeten Kühlmittelflansches.

Show it:

• 1 an electrical machine designed as a vehicle axle drive with a fluid cooling device in an axial sectional view;
• 2nd an enlarged section of the fluid cooling device of 1 in the area of a bearing plate of the electrical machine;
• 3rd a perspective view of the electrical machine in the area of the bearing plate of 3rd ;
• 4th a perspective view of a coolant flange formed on a housing of the electrical machine.

The figures show an electrical machine 1 , which is provided and designed in particular for driving an electric or hybrid vehicle. In particular, the electrical machine 1 intended for installation in or on a vehicle axle and thus provides an electric axle drive in conjunction with other components 2nd The electrical machine 1 thus delivers its power to vehicle wheels for moving the vehicle. In this respect, the electrical machine explained in detail below 1 going beyond that also an electric vehicle drive and a vehicle with such an electric machine 1 described.

The electrical machine 1 includes one in a housing 3rd fixed stator 4th with a stator laminated core 5 and with a stator winding 6 and a rotor 7 with a rotor laminated core 8th and with a short-circuit cage 9 . The electrical machine 1 is thus designed as an asynchronous machine. The rotor 7 is by means of a rotor shaft 10th , one on a first end shield 11 arranged first camp 13 and one on a second end shield 12th arranged second camp 14 around an axis A rotatable to the stator 4th stored. The rotor shaft 10th stands with an in 1 gearbox shown on the left 36 in operative connection, which can transmit the engine torque to vehicle wheels via further transmission elements, not shown here in the drawing.

The electrical machine 1 has a fluid cooling device through which a cooling fluid can flow 15 on, which absorbs a dissipated heat to an outside of the electrical machine 1 heat exchanger located.

The fluid cooler 15 includes a cooling tube 16 , which on a stator-fixed support element 17th , especially on the first end shield 11 is fixed and which one with on the bearing plate 11 provided fluid inlet 18th communicates. The cooling pipe 16 is axially only on one side through the end shield 11 mounted and extends with its largest section freely in the axial direction within a central recess 10a the rotor shaft 10th and forms to the rotor shaft 10th an annulus 10b out. The cooling pipe 16 is axially open on both sides and is thus at the same time as the annulus 10b and also with one on the first end shield 11 provided fluid outlet 19th in fluid communication. The first end shield 11 points to the formation of the fluid inlet 18th a central first through opening 11a and to form the fluid outlet 19th a second through opening arranged radially to the first through opening 11b on. Both through openings 11a , b thus occur on the rotor 7 facing mounting surface 11c from the end shield 11 out.

Between the rotor shaft 10th and that as a carrier element 17th acting end shield 11 is a sealing area 20th with a sealing element 21 intended. The sealing element 21 has the task of flowing through the cooling fluid from the fluid inlet 18th to the fluid outlet 19th a fluid transfer into an outside of the sealing area 20th lying area 22 of the electrical machine 1 to prevent at least essentially.

The sealing element 21 is available as an axial mechanical seal 23 is trained. The mechanical seal 23 includes a first section 23a which on the support element 17th is defined and further comprises a second section 23b which on the rotor shaft 10th is fixed and which one with the first section 23a is in a sealed connection. As in 2nd recognizable, the second section points 23b of the sealing element 21 an outer diameter which is smaller than an inner diameter of the first bearing 13 . The second section continues 23b the mechanical seal 23 at least partially axially overlapping to the first bearing 13 arranged.

Furthermore, the first camp 13 both on the mechanical seal 23 facing axial side as well as on the rotor core 8th facing axial side between a radially inner bearing ring 13a and a radially outer one Bearing ring 13b acting sealing arrangement 13c with two sealing washers 13d , e on. The warehouse interior 13f is further sealed against ingress of cooling fluid by means of a high speed grease. On the one hand, this makes the warehouse 13 lubricated and on the other hand, the created grease barrier prevents fluid from penetrating into the inner space 22 of the electrical machine 1 avoided.

For a noticeable increase in the fluid-cooled inner circumferential surface of the rotor shaft 10th and thus for the purpose of further improving the cooling effect, an inner diameter 10c the rotor shaft 10th or the central recess there 10a in the area of an axial extension of the rotor laminated core 8th be larger than in the area of the first bearing 13 .

As can be seen, the rotor shaft 10th formed as a hollow shaft and at the fluid inlet 18th Axial side facing away fluid-tight by a closure 24th locked. The fluid flow is experienced by the coaxial arrangement of the rotor shaft 10th and cooling pipe 16 a reversal of direction against the inflow direction and can on the axial side of the fluid inlet 18th flow out again, for which purpose only a sealing arrangement in the form of the sealing element on this side 21 is required.

From the first end shield 11 are the cooling pipe 16 , the first camp 13 and the stator-fixed section 23a of the sealing element 23 added. The first end shield 11 also takes one with the rotor shaft 10th interacting electrical equipotential bonding element 25th on. This is a potential equalization element 25th a slip ring arrangement 26 provided, which occurs as shaft voltages potential differences between the stator 4th and the rotor 7 degrades through electrical short circuit. The potential equalization element 25th is axially adjacent to the first bearing 13 arranged, in particular axially between the bearing 13 and the rotor laminated core 8th .

The cooling pipe 16 is on one of the end shield 11 or generally on the support element 17th provided attachment area 11f fixed. In particular, the cooling pipe 16 by means of a press fit into one of a base body 11d of the end shield 11 protruding axial process 11e arranged which the fastening area 11f trains. It can be seen in the figures that the fastening area 11f axially partially with the stator-fixed section 23a of the sealing element 21 or the mechanical seal 23 covered.

Returning to the assembly area 11c is a cover element there 27 made of a plastic with a web arrangement 27a arranged in a fluid-tight manner. Are by the web arrangement 27a between the end shield 11 and the cover element 27 and / or in the cover element 27 a fluid feed channel 28 and a fluid drain channel 29 educated.

The housing 3rd of the electrical machine 1 is a cast part made of a light metal material, in the present case made of an aluminum material. The housing 3rd forms a stator at the same time 4th external fluid cooling jacket 30th with a fluid channel arrangement 31 out. The housing 3rd points to the first end shield 11 facing side an integrally formed coolant flange 32 with two fluid channel sections 32a , b on which with the fluid inlet channel 28 and the fluid drain channel 29 of the cover element 27 are in fluid communication. The fluid channel section 32a forms an external coolant connection 40 out. Another external coolant connection, not shown here in the drawing, can be located, for example, in another position of the stator cooling jacket or in power electronics for controlling the electrical machine 1 be arranged, which with their housing and with their cooling circuit with the electrical machine 1 and with the fluid cooling device formed there 15 connected is. The further fluid channel section 32b forms a connection channel to the fluid cooling jacket 30th of the stator 4th out. The fluid cooler 15 can thus have a cooling section 15a for cooling the rotor 7 and a cooling section 15b for cooling the stator 4th have, which are successively flowed through by the cooling fluid and a fluid connection provided between them as a solid, tubeless connection channel 32b is trained.

Outside the sealing element 21 , that is on the side of the mechanical seal facing away from the flowing cooling fluid 23 is a leakage room 33 with a fluid collection area 34 provided in which a through the sealing area 20th passing portion of the cooling fluid can enter and be collected. The leakage room 33 also has a gas collection area 35 on which in an operating position of the electrical machine 1 opposite the fluid collection area 34 is geodetically higher. When using a cooling fluid with at least one volatile component, this can be done via the mechanical seal 23 escape and get into the gas collection area 35 collect.

If the cooling fluid exudes a solid-shaped component when the volatile component escapes, this component is also removed from the fluid collection area 34 added. To remove the solid-form component is at the fluid collection area 34 a lockable opening 34a with a removable cover 34b intended.

To remove one in the fluid collection area 34 Existing cooling fluid is a closable fluid drain opening 34c with a drain element 34d , in particular a drain plug or a drain plug. The fluid drain opening 34c is in an operating position of the electrical machine 1 oriented essentially geodetically downwards and opposite a gas discharge opening 35a of the gas collection area 35 geodetically arranged lower. The engagement opening of the cover is for easy removal of solids-like components 34b with a larger cross section than the fluid drain opening 35a educated.

The fluid drain opening 34c is provided at least approximately at a 6 o'clock position, that is to say between a 5 o'clock and a 7 o'clock position. The gas drain opening 35a on the other hand is provided at least approximately at a 12 o'clock position, that is to say between an 11 o'clock and a 01 o'clock position. The fluid collection area 34 and the gas collection area 35 are provided at least approximately in the same axial position. The mechanical seal can also be used 23 are at this axial position or at least axially with the fluid collection area 34 and / or the gas collection area 35 overlap.

The gas drain opening 35a of the gas collection area 35 also has a pressure compensation element 41 on, causing gas to escape from the gas collection area 35 is made possible. The pressure compensation element 41 comprises a semipermeable membrane which is permeable to air to allow pressure equalization, but is not permeable to fluid.

As mentioned earlier, is for bearing the rotor 7 in addition to the first camp 13 axially spaced the second bearing 14 provided which, if necessary, can also be designed axially on one or both sides with sealing rings and with a lubricant filling. The warehouse 14 is radial between the rotor shaft 10th and the second end shield 12th provided, with the rotor core 8th in an axial space between the first and second bearings 11 , 12th extends. As can be seen, the central recess extends for the purpose of improved cooling 10a inside the rotor shaft 10th axially through the second bearing 14 through it. The cooling pipe 16 extends within the rotor shaft 10th axially also via the second bearing 12th out. As can be seen further, the inside diameter of the rotor shaft 10th in the area of the axial extension of the rotor laminated core 8th and in the area of the second warehouse 12th larger than in the area of the first warehouse 11 .

In the illustrated embodiment, the rotor shaft has 10th one axially over the second bearing 12th protruding and into the transmission 36 leading shaft section with a gear wheel 37 trained output element 38 on. The central recess 10a the rotor shaft 10th extends axially into the area of the driven element 38 and can thus also be flowed through by the cooling fluid. According to a modification of the arrangement, the cooling pipe can 16 also extend axially into the area mentioned. The output element 38 and thus further elements in heat exchange and / or one outside the rotor shaft 10th Lubricant or coolant present can thus also be in the range of action of the fluid cooling device 15 arrive and be cooled.

As can be seen further in the figures, the output element 38 on the rotor shaft 10th axially between the second bearing 14 and a third camp 39 arranged. The central recess is sufficient 10a the rotor shaft 10th axially to the area of the third bearing 39 approach and is thus flowed through by the cooling fluid up to this position. The third camp 39 is thus also in the effective range of the fluid cooling device described above 15 .

In the above description, designations of functional elements have been chosen in part with reference to a fixed flow direction. In the electrical machine explained, the direction of flow of the cooling fluid within the fluid cooling device is fundamentally reversible. The functional elements designated with reference to the direction of flow are given the opposite meaning when the direction of flow is reversed. This means that, for example, a section or area designated as a fluid inlet now forms the fluid outlet, etc.

Reference list

1

electrical machine

2nd

Final drive

3rd

casing

4th

stator

5

Stator laminated core

6

Stator winding

7

rotor

8th

Rotor laminated core

9

Short circuit cage

10th

Rotor shaft

10a

Recess

10b

Annulus

10c

Inside diameter

11

End shield

11a

Through opening

11b

Through opening

11c

Mounting surface

11d

Basic body

11e

Axial process

11f

Fastening area

12th

End shield

13

warehouse

13a

inner bearing ring

13b

outer bearing ring

13c

Sealing arrangement

13d, e

Sealing washer

13f

Warehouse interior

14

warehouse

15

Fluid cooling device

15a

Rotor cooling section

15b

Stator cooling section

16

Cooling pipe

17th

Carrier element

18th

Fluid inlet

19th

Fluid outlet

20th

Sealing area

21

Sealing element

22

Room area

23

Mechanical seal

23a

first section

23b

second part

24th

Clasp

25th

Equipotential bonding element

26

Slip ring arrangement

27

Cover element

27a

Bridge arrangement

28

Fluid inlet channel

29

Fluid drain channel

30th

Fluid cooling jacket

31

Fluid channel arrangement

32

Coolant flange

32a, b

Fluid channel section

33

Leakage room

34

Fluid collection area

34a

lockable opening

34b

Sealing cover

34c

Fluid drain opening

34d

Drain element

35

Gas collection area

35a

Gas drain opening

36

transmission

37

gear

38

Output element

39

warehouse

40

external coolant connection

41

Pressure compensation element

A

Axis of rotation

QUOTES INCLUDE IN THE DESCRIPTION

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

Patent literature cited

• WO 2016/050534 A1 [0001]

Claims (6)

Electrical machine (1) with a fluid cooling device (15), comprising - a stator (4) with a stator lamination stack (5) and with a stator winding (6), - a rotor (7) with a rotor lamination stack (8), which by means of a rotor shaft (10) and a first bearing (13) which is arranged on a first bearing plate (11) and is rotatable about an axis (A) relative to the stator (4) and wherein - the fluid cooling device (15) has a cooling tube (16) which is fixed to a stator-fixed support element (17) of the electrical machine (1) and is connected to a fluid inlet (18) and which is located axially within a central recess (10a) of the rotor shaft (10) and with the formation of an annular space ( 10b) extends to the rotor shaft (10), wherein - the cooling tube (16) is in fluid connection with the annular space (10b) and with a fluid outlet (19) and - between the rotor shaft (10) and the carrier element (17) a sealing area (20) with a sealing element (21) is provided which, when a cooling fluid flows through from the fluid inlet (18) to the fluid outlet (19), at least essentially prevents fluid transfer into a space (22) of the electrical machine (1) lying outside the sealing region (20), - the sealing element (21) prevents a first Section (23a) which is fixed to the carrier element (17) and further comprises a second section (23b) which is fixed to the rotor shaft (10) and which is in sealing connection with the first section (23a), characterized in that that - the second section (23b) of the sealing element (21) has an outer diameter which is smaller than an inner diameter of the first bearing (13), and - the first bearing (13) at least on the axial side facing the sealing element (21) between a radially inner and a radially outer bearing ring (13a, 13b) acting sealing arrangement (13c), through which a bearing interior (13f) against penetration of Cooling fluid is sealed. Electrical machine after Claim 1 , characterized in that the second section (23b) of the sealing element (21) is at least partially axially overlapping to the first bearing (13). Electrical machine after Claim 1 or 2nd , characterized in that the sealing element (21) is designed as a mechanical seal (23), in particular as an axial mechanical seal and in particular as a Levitex seal. Electrical machine according to one of the Claims 1 to 3rd , characterized in that the first bearing (13) has a sealing arrangement (13c) on both axial sides. Electrical machine after Claim 4 , characterized in that the bearing interior (13f) is filled with a pasty lubricant, in particular with a high-speed grease. Electrical machine according to one of the Claims 1 to 5 , characterized in that an inner diameter of the rotor shaft (10) in the area of the first bearing (13) is smaller than in the area of an axial extension of the rotor laminated core (8).

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