DE102016204959A1 - Drive arrangement with an electric machine and a Sprühkühlanordnung for cooling the electric machine - Google Patents

Abstract

Drive arrangement (1) for a motor vehicle comprising an electric machine (2) with a stator (3) and a rotor (4), wherein the stator (3) and the rotor (4) in an interior (5) of a housing (6) and a spray cooling arrangement (7), wherein the stator (3) and / or the rotor (4) of the electric machine (2) are at least partly coolable by spraying with a liquid refrigerant by means of the spray cooling arrangement (7) in a cooling operation, wherein during the cooling operation, the liquid refrigerant at the stator (3) and / or the rotor (4) of the electric machine (2) at least partially evaporated and wherein the gaseous refrigerant and / or the liquid refrigerant via at least a first line (8) the interior (5) of the housing (6) are discharged, characterized in that in the first conduit (8), a first control valve (9) is arranged, via the first control valve (9) of the vapor pressure in the interior (5) of housing (6) is adjustable.

Description

Field of the invention

The present invention relates to a drive assembly for a motor vehicle comprising an electric machine with a stator and a rotor, wherein the stator and the rotor are arranged in an interior of a housing, and a Sprühkühlanordnung, wherein by means of the Sprühkühlanordnung in a cooling operation of the stator and / or the rotor of the electric machine are at least partially coolable by spraying with a liquid refrigerant, wherein during the cooling operation, the liquid refrigerant at the stator and / or the rotor of the electric machine at least partially evaporated and wherein the gaseous refrigerant and / or the liquid refrigerant over at least a first line from the interior of the housing can be discharged.

State of the art

Drive arrangements of the type mentioned find application in a wide variety of vehicle configurations, with the electrical machine of such a drive arrangement being or can only be operated within certain operating temperature limits, depending on the configuration.

Electric machines include a fixed stator and a movable rotor, wherein the rotor is mounted in the most common type of electrical machine rotatably within a ring-shaped stator. The stator has a stator core and at least one stator winding arranged on the stator core. Furthermore, the rotor may comprise a rotor core and at least one rotor winding arranged on the rotor core.

Electric machines generate heat due to the dielectric loss during their operation. Predominantly, in the region of the stator winding and / or the rotor winding, in particular in the region of the respective winding heads, there is a strong evolution of heat. The result of this intense heating is an increase in the dielectric loss factor - even more electrical energy is converted to heat, which in turn causes a deterioration in the efficiency of the electric machine and on the other hand adversely affects reliable operation of the electric machine over its lifetime. Therefore, a cooling device is generally provided in drive assemblies with electric machines, which cools the parts to be cooled of the electric machine.

Conventional cooling for electrical machines use a circulating gaseous or liquid coolant. The coolant circulates, for example, in a housing of the electric machine or in a rotor shaft designed as a hollow shaft, on which the rotor of the electric machine is arranged. Due to its heat capacity, the liquid coolant absorbs the heat and transports it away. These solutions usually take place at a great distance from the heat source and require heat conduction through the rotor core and / or the stator core in order to dissipate the waste heat into the cooling circuit. By means of this diffuse heat conduction often adjacent parts such as bearings, seals, etc. are heated and thus thermally stressed.

In addition, cooling devices are also known which effect cooling of surfaces to be cooled of an electrical machine due to the evaporation of a coolant. The coolant is vaporized at the surface to be cooled and then recondensed again. For example, the document describes US 7,397,154 B2 a spray-cooled engine system having a motor housing with an interior space and an exterior space, wherein the stator and the rotor are arranged in the interior of the housing. Furthermore, the engine system includes a plurality of atomizers configured to spray at least the stator and the rotor from the atomizer. Furthermore, the disclosed engine system includes a coolant pump which communicates with the atomizers and supplies the atomizers with coolant. The coolant is, for example, a dielectric fluid that evaporates on the surfaces to be cooled of the stator and the rotor. The recondensation of the coolant takes place on the housing inner wall of the housing. In this case, however, the heat dissipation by the coolant is severely limited.

Summary of the invention

It is an object of the invention to provide an improved drive arrangement with an electric machine and a spray cooling arrangement, which allows a variable cooling of the electric machine and thus a performance-optimized operation of the drive arrangement.

The object is achieved by a drive arrangement for a motor vehicle comprising an electric machine with a stator and a rotor, wherein the stator and the rotor are arranged in an interior of a housing, and a Sprühkühlanordnung, wherein by means of the Sprühkühlanordnung in a cooling operation of the stator and / or the rotor of the electric machine by spraying with a liquid refrigerant are at least partially coolable, wherein during the cooling operation, the liquid refrigerant to the stator and / or the rotor of the electric machine at least partially evaporated and wherein the gaseous refrigerant and / or the liquid refrigerant can be discharged via at least a first line from the interior of the housing, wherein in the first line, a first control valve is arranged, wherein via the first control valve, the vapor pressure is adjustable in the interior of the housing.

The electric machine according to the invention comprises a stator, a rotor and a housing, wherein the stator and the rotor are arranged in an inner space of the housing.

According to the invention, the electric machine, more precisely the stator and / or the rotor of the electric machine, can be cooled at least partially in a cooling operation of the drive arrangement by means of the spray cooling arrangement. The cooling of the stator and / or rotor takes place by means of at least partial spraying of the surfaces to be cooled of the stator and / or rotor with a liquid refrigerant. According to the present invention, the liquid refrigerant evaporates at least partially on the surfaces to be cooled of the stator and / or rotor - it forms a first phase, namely gaseous refrigerant, and / or a second phase, namely liquid refrigerant.

According to the present invention, the gaseous refrigerant and / or the liquid refrigerant can be discharged from the interior of the housing via at least one first line.

In the first line according to the invention, a first control valve is arranged, wherein the vapor pressure in the interior of the housing can be regulated via the first control valve.

The evaporation of the refrigerant ensures a homogeneous temperature of the surfaces to be cooled. The refrigerant heats up to the surfaces of the electric machine to be cooled until the start of an evaporation dependent on the respective vapor pressure on the surface to be cooled and leads on the one hand by the warming to the boiling temperature and on the other hand by the latent heat of vaporization of the surface to be cooled of the electrical Machine off. The vapor pressure can be adjusted by the first control valve. The surface temperature of the component to be cooled of the electric machine is thus adjustable via the vapor pressure in the interior of the housing of the electric machine and it ensures a performance-optimized operation of the drive assembly.

Further developments of the invention are specified in the dependent claims, the description and the accompanying drawings.

The spray cooling arrangement preferably comprises a refrigerant tank for holding the liquid refrigerant, a refrigerant pump, at least one spray unit and a condenser.

Via the refrigerant pump, the liquid refrigerant from the refrigerant tank to the spray unit is conveyed. The refrigerant pump is preferably designed as a controllable pump. In this way, it is possible to control the amount of liquid refrigerant to be delivered and thus to positively influence the efficiency of the spray cooling arrangement.

By means of the use of a spray unit, it is possible to spray the refrigerant directly onto the surfaces of the electric machine to be cooled and to effect a homogeneous distribution of the refrigerant over the surfaces of the electric machine to be cooled. By this direct cooling of the heat sources, the thermal resistances can be reduced. Furthermore, even a low refrigerant mass flow is sufficient to wet the surfaces of the electrical machine to be cooled with refrigerant.

The condenser is preferably connected on the input side via the first line and the first control valve to the interior of the housing of the electric machine such that gaseous refrigerant and / or liquid refrigerant can flow from the interior of the housing into the condenser during the cooling operation.

Preferably, the capacitor is connected on the output side to the refrigerant tank.

Further preferably, the refrigerant tank is connectable via a second line and a second valve to the interior of the housing of the electric machine, so that during the cooling operation liquid refrigerant can flow from the interior of the housing directly into the refrigerant tank.

By connecting the condenser and / or the refrigerant tank to the interior of the housing of the electric machine via the first line and / or the second line, the drive arrangement can be further adapted to specific space requirements within the motor vehicle individually.

Preferably, the second conduit opens with respect to the installation position of the drive assembly, starting from a deepest portion of the housing in the refrigerant tank.

By forming the second line with the second control valve, in particular the fact that the second line with respect to the installation position of the drive assembly of the deepest portion opens into the refrigerant tank, a particularly reliable drainage of the liquid refrigerant is ensured from the interior of the housing and prevents splashing of the stator and / or rotor in the liquid refrigerant and thus a loss of power of the electric machine by splashing losses.

The refrigerant is preferably an electrically non-conductive liquid having a boiling point at ambient pressure between 60 ° C and 100 ° C, in particular between 60 ° C and 80 ° C.

Known applications for spray cooling usually use special electrically non-conductive oils. Due to their dielectric properties, these can be sprayed directly onto the surface to be cooled, for example the winding surface, but do not evaporate there due to the maximum permissible surface temperature. The fine oil film drips from the surface to be cooled back into the oil sump and there returns the heat absorbed to the housing wall or is pumped from there to a heat exchanger.

Due to the inventive design of the drive assembly, in particular by the inventive design of the Sprühkühlanordnung, the drive assembly can be operated optimized performance. In this case, the use of the capacitor requires a particularly efficient recondensation of the gaseous refrigerant and an optimized heat dissipation from the interior of the housing.

Brief description of the drawings

The invention will now be described by way of example with reference to the drawings.

Fig. Shows a schematic representation of an exemplary drive arrangement.

Detailed description of the invention

The exemplary drive arrangement shown in FIG 1 includes an electric machine 2 and a spray cooling arrangement 7 ,

The electric machine 2 has a housing 6 , a stator 3 and a rotor 4 on. The stator 3 and the rotor 4 are in an interior 5 of the housing 6 arranged, the stator 3 is annular and the rotor 4 surrounds outside. A reverse arrangement, namely an arrangement in which the rotor 4 is annular and the stator 3 Surrounds outside, is also conceivable.

The rotor 4 is fixed on a rotor shaft 19 arranged. The rotor shaft 19 is through an opening in the housing 6 from the interior 5 of the housing 6 guided.

The stator 3 has a stator core 20 and a stator winding 21 on. The rotor 4 has a rotor core 22 and a rotor winding 23 on.

The spray cooling arrangement 7 includes a refrigerant tank 13 with liquid refrigerant, a refrigerant pump 10 , a filter element 17 , two spray units 11 and a capacitor 12 ,

The filter element 17 is between the refrigerant pump 10 and the two spray units 11 arranged and prevents the finest impurities in the refrigerant to reach the spray nozzles and clog them. An arrangement of the filter element 17 between the refrigerant tank 13 and the refrigerant pump 10 is also conceivable. Furthermore, it is conceivable several filter elements 17 within the spray cooling arrangement 7 to arrange.

In a cooling operation of the drive assembly 1 In the case of the embodiment shown schematically in FIG. 1, the head of the stator winding will be 21 and the head of the rotor winding 23 cooled. The cooling takes place by liquid refrigerant from the refrigerant tank 13 via the refrigerant pump 10 to the two spray units 11 is encouraged. The spray units 11 are like the stator 3 and the rotor 4 in the interior 5 of the housing 6 the electric machine 2 arranged. About the spray units 11 the liquid refrigerant is atomized. The spray units 11 are formed such that the surfaces to be cooled of the stator 3 and the rotor 4 be sprayed flat with liquid, atomized refrigerant - such is continuously a thin film of refrigerant on the head of the stator winding 21 and on the head of the rotor winding 23 applied. The liquid refrigerant vaporizes on the surface of the stator to be cooled 3 and on the surface to be cooled of the rotor 4 at least partially and it forms gaseous refrigerant and depending on the degree of evaporation and liquid refrigerant. The gaseous refrigerant rises within the interior 5 of the housing 6 the electric machine 2 essentially in the direction of a highest section 18 of the housing 6 on. The non-evaporated, liquid refrigerant drips from the surfaces of the stator to be cooled 3 and the rotor 4 in a deepest section 16 of the housing 6 the electric machine 2 ,

The interior 5 of the housing 6 the electric machine 2 is in the present embodiment via a first line 8th and a first control valve 9 on the input side with the capacitor 9 connectable. The first line 8th opens in the present example with respect to the mounting position of drive arrangement 1 starting from the highest section 18 of the housing 6 in the condenser 12 , About the first line 13 can during the cooling operation gaseous refrigerant from the interior 5 of the housing 6 in the condenser 12 stream.

Furthermore, the interior is 5 of the housing 6 the electric machine 2 over a second line 14 and a second control valve 15 with the refrigerant tank 13 connectable. The second line 14 opens with respect to the installation position of the drive assembly 1 starting from the deepest section 16 of the housing 6 in the refrigerant tank 13 , About the second line 14 can during the cooling operation liquid refrigerant from the interior 5 of the housing 6 in the refrigerant tank 13 flow.

The capacitor 9 is on the output side with the refrigerant tank 8th connected.

LIST OF REFERENCE NUMBERS

1

drive arrangement

2

Electric machine

3

stator

4

rotor

5

inner space

6

casing

7

Sprühkühlanordnung

8th

First line

9

First control valve

10

Refrigerant pump

11

spray

12

capacitor

13

Refrigerant tank

14

Second line

15

Second control valve

16

Deepest section

17

filter element

18

Highest section

19

rotor shaft

20

stator core

21

stator

22

rotor core

23

rotor winding

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 7397154 B2 [0006]

Claims (7)

Drive arrangement ( 1 ) for a motor vehicle comprising - an electric machine ( 2 ) with a stator ( 3 ) and a rotor ( 4 ), wherein the stator ( 3 ) and the rotor ( 4 ) in an interior ( 5 ) of a housing ( 6 ), and - a spray cooling arrangement ( 7 ), whereby by means of the spray cooling arrangement ( 7 ) in a cooling operation of the stator ( 3 ) and / or the rotor ( 4 ) of the electric machine ( 2 ) are at least partially coolable by spraying with a liquid refrigerant, wherein during the cooling operation the liquid refrigerant is at the stator ( 3 ) and / or the rotor ( 4 ) of the electric machine ( 2 ) is at least partially evaporated and wherein the gaseous refrigerant and / or the liquid refrigerant via at least a first line ( 8th ) from the interior ( 5 ) of the housing ( 6 ) are dischargeable, characterized in that in the first line ( 8th ) a first control valve ( 9 ) is arranged, via the first control valve ( 9 ) the vapor pressure in the interior ( 5 ) of the housing ( 6 ) is controllable. Drive arrangement ( 1 ) according to claim 1, characterized in that the spray cooling arrangement ( 7 ) a refrigerant tank ( 13 ), for receiving the liquid refrigerant, a refrigerant pump ( 10 ), at least one spray unit ( 11 ) and a capacitor ( 12 ). Drive arrangement ( 1 ) according to claim 2, characterized in that the capacitor ( 12 ) on the input side via the first line ( 8th ) and the first control valve ( 9 ) with the interior ( 5 ) of the housing ( 6 ) of the electric machine ( 2 ) is connectable. Drive arrangement ( 1 ) according to claim 2 or 3, characterized in that the capacitor ( 12 ) on the output side with the refrigerant tank ( 13 ) connected is. Drive arrangement ( 1 ) according to claim 2, 3 or 4, characterized in that the refrigerant tank ( 13 ) via a second line ( 14 ) and a second control valve ( 15 ) with the interior ( 5 ) of the housing ( 6 ) of the electric machine ( 2 ) is connectable. Drive arrangement ( 1 ) according to claim 5, characterized in that the second line ( 14 ) with respect to the installation position of the drive arrangement ( 1 ) starting from a deepest section ( 16 ) of the housing ( 6 ) in the refrigerant tank ( 13 ) opens. Drive arrangement ( 1 ) according to any one of the preceding claims, characterized in that the refrigerant is an electrically non-conductive liquid having a boiling point at ambient pressure between 60 ° C and 100 ° C.

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