DE102021205055A1 - Electric machine with a cooling device - Google Patents

Abstract

In order to create an electrical machine with a cooling device which enables more effective and advantageously controllable cooling of the winding overhangs of the electrical machine, an electrical machine (100) comprising a stator (10), a rotor (11) rotatably mounted in the stator (10) and a cooling device (24), the stator (10) having a winding overhang (16), the cooling device (24) being designed for fluid cooling of the winding overhang (16), the cooling device (24) having a reaction turbine (23). Has outlet openings (28) for a fluid, the outlet openings (28) being arranged and aligned in such a way as to guide a fluid exiting from the outlet openings (28) onto a radially inner side (30) of the end winding (16).

Description

The present invention relates to an electrical machine comprising a stator, a rotor rotatably mounted in the stator and a cooling device, the stator having a winding overhang, the cooling device being designed for fluid cooling of the winding overhang, the cooling device having a reaction turbine with outlet openings for a fluid .

In many electrical machines, the winding overhang is cooled by oil cooling. In the known type of oil cooling, oil is supplied through a hollow rotor shaft of the rotor. The oil escapes from the rotor shaft via radial holes in the rotor shaft. As the oil exits the rotating rotor shaft, it is accelerated outwards in the radial direction so that the oil hits the end winding and cools it.

A disadvantage of the known oil cooling is that when the rotor is stationary, there is little or no oiling and thus cooling of the end winding. The reason for this is that there must be a minimum speed of the rotor in order to give the oil exiting the bores sufficient speed. In electrical machines that are used to drive motor vehicles, the minimum speed is not reached, for example, when driving uphill with a trailer.

A further problem is that with a known oil cooling system, the end winding cannot be post-cooled when the rotor is stationary.

With the known oil cooling, the cooling capacity is influenced by the quantity of oil supplied, as well as by throttling resistances in the rotor shaft and the rotor speed. There are therefore only a few possibilities for influencing the control of the cooling capacity.

Another problem occurs in electrical machines in which the stator has a winding overhang on both sides. Since the oil is only supplied from one end of the rotor shaft, there is less hydraulic pressure at the end of the rotor shaft facing away from the supply due to friction losses, resulting in asymmetrical cooling of the end windings. Yet another problem is that rotating with the rotor shaft

amount of oil can lead to an unequal distribution of mass, causing the entire system to become unbalanced. It was therefore proposed in the prior art to reduce the drive power of the electric machine as the temperature of the coil or the end winding increases, or to provide bores of different sizes on the two end sides of the rotor shaft.

the DE 10 2014 212 198 A1 discloses an electric machine with a hybrid cooler. The hybrid cooler has a propeller that can be rotated about an axis of rotation, the propeller comprising a plurality of blade blades, which blade blades are arranged around the axis of rotation and are designed to generate a directed air flow when the propeller rotates. Furthermore, the blades each have a fluid channel extending along the blade, with at least one opening of the fluid channel being provided in an end region of the blade, which is aligned and designed in such a way that a fluid flowing through the fluid channel and emerging from the opening causes the propeller to rotate. When the propeller rotates about the axis of rotation, the openings describe an approximately circular path, which is approximately congruent with the circular end winding.

the U.S. 2014/0271128 A1 discloses a turbocharger assembly having a shaft and turbine wheel assembly. The assembly further includes a component having inner and outer surfaces and one or more passageways extending between the inner and outer surfaces. The passages are configured to exert a force on the component that rotates the component about the axis of rotation, the force being due to a flow of a fluid in the passages.

From the DE 10 2012 210 120 A1 an electrical machine with separate cooling circuits is known. The electrical machine comprises a rotor and a stator, a first cooling circuit and at least one second cooling circuit, the stator having a stator core with windings which protrude from the stator core at a winding exit area at the two axial ends of the rotor and each form an associated end winding . In the first cooling circuit, a first cooling medium is circulated by means of a first turbomachine that can be controlled independently of the speed of the rotor. In the second cooling circuit, a second cooling medium is circulated by means of a second turbomachine that can be controlled independently of the speed of the rotor. The rotor and the laminated core of the stator can be cooled using the first cooling medium. The second cooling circuit is fluidically separated from the first cooling circuit by means of a housing which, together with the respective winding outlet area, encloses at least one of the associated end windings.

The present invention is based on the object of creating an electrical machine with a cooling device which enables more effective and advantageously controllable cooling of the winding overhangs of the electrical machine.

In order to achieve the object on which the invention is based, an electrical machine is proposed comprising a stator, a rotor rotatably mounted in the stator and a cooling device, the stator having a winding overhang, the cooling device being designed for fluid cooling of the winding overhang, the cooling device having a reaction turbine Has outlet openings for a fluid, it also being provided that the outlet openings are arranged and aligned in such a way as to direct a fluid exiting from the outlet openings to a radially inner side of the end winding.

The fluid used for fluid cooling can be oil, water or another suitable liquid. Furthermore, the fluid can also be a gas or gas mixture.

According to the invention, the arrangement and alignment of the outlet openings is designed in such a way that a fluid in the cooling mode, that is to say when the fluid exits from the outlet openings, is guided onto a radially inner side of the end winding.

The cooling device is designed as a reaction turbine. A reaction turbine is understood to mean a turbine in which a fluid emerging from outlet openings of the reaction turbine causes a force on the reaction turbine which has at least one tangential component, and the reaction turbine is caused to rotate.

For fluid cooling, the fluid, in particular the oil, is fed to the reaction turbine under hydrostatic pressure. The fluid, which is under hydrostatic pressure, emerges from the outlet openings. A rotation of the reaction turbine is generated by the flow momentum thus generated. Furthermore, the fluid is evenly distributed on the radially inner side of the end winding by the rotation. The flow impulse of the fluid from the reaction turbine or from the outlet openings of the reaction turbine accelerates the reaction turbine until the torque generated by the flow impulse is in equilibrium with the friction torque.

An advantage of the electrical machine according to the invention is that the fluid emerging from the outlet openings during cooling operation, in particular the oil, hits the radially inner side of the winding overhang, so that a large part of the fluid, essentially all of the fluid, is used to cool the winding overhang. In addition, the winding overhang can also be cooled at low rotor speeds, since the speed of the reaction turbine is independent of the speed of the rotor. It can thus also be an after-cooling for the end winding.

Provision is preferably made for the reaction turbine to have outlet nozzles, with the outlet nozzles comprising the outlet openings.

Provision is preferably made for the outlet openings, preferably the reaction turbine, to be arranged in a plane including the end winding perpendicular to an axis of rotation of the rotor, so that the outlet openings, preferably the reaction turbine, are arranged in an interior space radially delimited by the end winding.

The plane that encompasses the end winding is an imaginary plane or disk that is aligned perpendicular to the axis of rotation of the rotor. In the radial direction, the winding overhang delimits an essentially disc-shaped interior space, with a diameter corresponding to the inner diameter of the winding overhang and a height or thickness corresponding to the height of the winding overhang. The outlet openings, preferably the reaction turbine or essential parts of the reaction turbine, are arranged in this interior space and lie in the plane comprising the end winding.

Due to the arrangement of the outlet openings in the plane or in the interior, these, or the outlet nozzles comprising the outlet openings, can have an orientation without a component in the axial direction of the electrical machine. Instead, the outlet openings, or the outlet nozzles comprising the outlet openings, are essentially aligned in a radial and a tangential direction. A more efficient distribution of the fluid is brought about by this arrangement and orientation, since the fluid emerging from the outlet openings has no axial velocity component and therefore does not or hardly ever strike the rotor body. In addition, a more compact construction of the electrical machine can be achieved by arranging the outlet openings and in particular the reaction turbine or essential parts of the reaction turbine in the interior. Furthermore, since the exiting fluid has no axial velocity component, efficient acceleration of the reaction turbine is effected.

It is preferably provided that the cooling device comprises at least two reaction turbines.

In this case, it can further preferably be provided that the at least two reaction turbines are arranged on opposite end sides of the electrical machine and are designed for fluid cooling in each case of a winding overhang arranged on the respective end side.

The end faces located at the axial ends of the electrical machine usually each have a winding overhang. By arranging one reaction turbine at each of the two end faces, the winding overhangs located there can be cooled independently of one another and with the same cooling capacity. In contrast to the well-known oil cooling, in which a fluid is passed through the rotating rotor shaft, a symmetrical cooling of the two end windings is thus made possible.

Provision is preferably made for the reaction turbine to be mounted so as to be rotatable about a rotor shaft.

A rotor body is preferably attached to the rotor shaft. The reaction turbine and the rotor shaft are mounted independently of one another, but have a common axis of rotation.

It can preferably be provided that the electrical machine has a housing with a housing cover, the housing cover comprising a first bearing, in particular a roller or ball bearing, for the rotor shaft and a second bearing, in particular a plain bearing or a roller bearing, for the reaction turbine. more preferably the first bearing and the second bearing are arranged concentrically to one another in one plane, even more preferably on a pin of the housing cover.

The housing cover usually has a mount for the bearing of the rotor shaft. A bearing for the rotor shaft is arranged in the receptacle, which is usually designed as a roller or ball bearing. It is now preferably provided that the bearing for the reaction turbine is also arranged on the housing cover. For this purpose, a preferably inwardly directed pin can be provided on the housing cover. The journal includes a central opening which forms the seat for the rotor shaft. The first bearing for the rotor shaft is arranged in the central opening or in the receptacle. The reaction turbine can be mounted on the second bearing on the outside of the journal. By arranging both the first bearing for the rotor shaft and the second bearing for the reaction turbine on the journal, the two bearings can be arranged essentially concentrically to one another and in a common plane perpendicular to the axis of rotation. The concentric arrangement of the two bearings improves the smooth running of the electric machine.

Provision is preferably made for the housing cover to have a supply line for the fluid to the reaction turbine, and for the reaction turbine to be connected to the housing cover by means of a rotary leadthrough for the fluid.

The fluid is fed from an outside through a supply line provided in the housing cover to the reaction turbine arranged inside the electrical machine. The reaction turbine is mounted on the housing cover, preferably on the journal, by means of a rotary feedthrough. The fluid subjected to hydrostatic pressure can be supplied to the reaction turbine by means of the rotary leadthrough, so that the fluid is pressed out of the outlet openings under the hydrostatic pressure.

With a further advantage it can be provided that the rotary feedthrough is designed for cooling the first bearing.

Thus, by means of the cooling device, not only can the winding overhang be cooled, but the first bearing of the rotor shaft can also be cooled and/or oiled. For this purpose, the rotary feedthrough can optionally have a further feed line for the fluid to the first bearing, in particular to the roller or ball bearing for the rotor shaft. This second supply line can run at least partially through the spigot of the housing cover.

A further possibility is that the seal of the rotary feedthrough is designed in such a way that a small amount of leakage of the fluid is permitted in the area of the first bearing, which ensures that the first bearing is cooled and/or lubricated.

Provision can preferably be made for at least two reaction turbines to be arranged on the same end side of the electrical machine.

The at least two reaction turbines can thus be arranged on the same housing cover. It is preferably provided that the axes of rotation of the at least two reaction turbines run parallel to the axis of rotation of the rotor shaft.

Preferably, the at least two reaction turbines on the housing cover in the radial direction between the rotor shaft, respectively the journal for the bearing of the rotor shaft, and the end winding.

More preferably, at least two further reaction turbines can also be provided on the second housing cover.

Provision is particularly preferably made for four reaction turbines to be arranged on the same end side of the electrical machine.

In particular, it can be provided that several reaction turbines are distributed evenly around the rotor shaft.

Decentralized fluid cooling is thus provided.

Furthermore, it is preferably provided that guide vanes or guide plates are arranged in the space between the rotor shaft and the reaction turbines, in particular between the journal of the housing cover supporting the rotor shaft and the reaction turbines preferably arranged on the housing cover.

The guide vanes or baffle plates serve to divert the fluid exiting from the outlet openings of the several reaction turbines from the angle area that cannot be used directly, ie that inner area of the electrical machine in which the rotor shaft is arranged, in the direction of the end winding.

With four reaction turbines arranged on the same housing cover, each of the reaction turbines covers approximately a quarter of the radially inner side of the end winding for cooling.

According to the invention, it can also be provided that an outlet angle of the fluid from the outlet openings is designed to be controllable.

For example, the outlet nozzles of the reaction turbine, which contain the outlet openings, can be mechanically aligned. The rotational speed of the reaction turbine can be optimized by aligning the outlet opening or the outlet nozzles with the outlet openings. If the tangential component of the outflowing fluid is increased compared to the radial component, the speed of the reaction turbine is increased. Conversely, if the tangential component is reduced in relation to the radial component, then the speed of the reaction turbine is reduced.

The cooling capacity of the cooling device can be achieved by controlling the amount of oil. The oil quantity control can in turn be based on the hydraulic state variables pressure and volume flow of the fluid. Further controlled variables for the amount of fluid, in particular for the amount of oil, can be the winding temperature, the fluid temperature and the electrical resistance losses of the electrical machine.

The invention is explained in more detail below with reference to the accompanying figures.

• 1a einen Längsschnitt durch eine elektrische Maschine mit einer Kühlvorrichtung,
• 1b eine Querschnittsansicht durch die elektrische Maschine der 1a,
• 2a einen Längsschnitt durch eine weitere elektrische Maschine mit einer Kühlvorrichtung, und
• 2b eine Querschnittsansicht durch die elektrische Maschine der 2a.

Show it:

• 1a a longitudinal section through an electrical machine with a cooling device,
• 1b a cross-sectional view through the electric machine 1a ,
• 2a a longitudinal section through another electrical machine with a cooling device, and
• 2 B a cross-sectional view through the electric machine 2a .

1a shows an electrical machine 100 in a longitudinal section. 1b shows the electric machine 100 in a cross-sectional view. The electrical machine 100 includes a stator 10 and a rotor 11 rotatably mounted in the stator 10 . The rotor 11 has a rotor shaft 12 and a rotor body 13 . The stator 10 has two end faces 14, 15, with a winding overhang 16 being provided on each of the two end faces 14, 15. The electrical machine 100 is closed at each of the end faces 14, 15 with a housing cover 17. Each of the housing covers 17 has an inwardly directed journal 18 which has a receptacle 19 with a first bearing 21 for the rotor shaft 12 designed as a ball bearing 20 therein. A second bearing 22 for a reaction turbine 23 of a cooling device 24 is also provided on each of the journals 18 . The reaction turbine 23 is rotatably mounted around the journal 18 . A fluid, in particular oil, can be supplied to the reaction turbine 23 under hydrostatic pressure through a supply line 25 running in the housing cover 17 and a rotary leadthrough 26 . The fluid subjected to the hydrostatic pressure emerges from outlet openings 28 of the reaction turbine 23 provided in outlet nozzles 27 . The flow momentum of the exiting fluid causes the reaction turbine 23 to rotate. The outlet openings 28 are arranged in an interior space 29 which is radially delimited by the end winding 16 and is delimited in the axial direction by the housing cover 17 and the rotor body 13 . The outlet openings 28 or the outlet nozzles 27 having the outlet openings 28 are aligned in such a way that the fluid exiting from the outlet openings 28 is directed onto a radially inner side 30 of the end winding 16 .

The reaction turbine 23 has, as in particular in 1b as can be seen, at least two outlet nozzles 27 aligned at an angle α to a tangential direction 31 . The fluid is supplied to the outlet nozzles 27 and the outlet openings 28 by means of a pump 32 through the feed line 25 and the rotary feedthrough 26 . The fluid emerging from the outlet openings 28 causes the reaction turbine 23 to rotate about the journal 18 of the respective housing cover 17. The arrangement and alignment of the outlet openings 28 and the outlet nozzles 27 in the area delimited by the end winding 16, the rotor body 13 and the housing cover 17 Interior 29, the fluid emerging from the outlet openings 28, in particular the oil, is distributed evenly on the radially inner side 30 of the respective end winding 16. The reaction turbine 23 or the rotary feedthrough 26 or the journal 18 also includes a second supply line 33 which is designed to supply the fluid to the first bearing 21 designed as a ball bearing 20 . The angle of attack α of the outlet nozzles 27 can be adjustable in a preferred embodiment. When the angle α increases, the speed of the reaction turbine 23 decreases. If, on the other hand, the angle α decreases, the speed of the reaction turbine 23 increases.

the 2a and 2 B show another electric machine 100 in accordance with the invention. Identical or similar components are given the same reference numbers as in FIGS 1a and 1b marked. The electric machine 100 after 2a and 2 B differs from the electrical machine 100 according to 1a and 1b in that four reaction turbines 23 of the cooling device 24 are arranged on each of the housing covers 17 . The reaction turbines 23 are arranged on the respective housing cover 17 between the pin 18 of the housing cover 17 and the end winding 16 . Each of the reaction turbines 23 is supplied with a fluid by means of a supply line 25 in the housing cover 17 . The fluid is routed to the outlet nozzles 27 with the outlet openings 28 via a rotary feedthrough 26 . In order to increase the efficiency of the cooling device 24, as shown in the cross-sectional view of FIG 2 B shown, guide vanes or guide plates 34 are provided, which enclose the pin 18 or the rotor shaft 12 . By means of the guide plates 34, fluid sprayed inwards in the radial direction from the individual reaction turbines 23 can be diverted away from the angle range that cannot be used directly.

reference list

100

electrical machine

10

stator

11

rotor

12

rotor shaft

13

rotor body

14

end page

15

end page

16

winding head

17

housing cover

18

cones

19

recording

20

ball-bearing

21

First camp

22

Second camp

23

reaction turbine

24

cooler

25

supply line

26

rotary joint

27

outlet nozzle

28

exit port

29

inner space

30

Inner side

31

tangential direction

32

pump

33

supply line

34

baffle

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102014212198 A1 [0008]
• US 2014/0271128 A1 [0009]
• DE 102012210120 A1 [0010]

Claims (10)

Electrical machine (100) comprising a stator (10), a rotor (11) rotatably mounted in the stator (10) and a cooling device (24), the stator (10) having an end winding (16), the cooling device (24) is designed for fluid cooling of the end winding (16), the cooling device (24) having a reaction turbine (23) with outlet openings (28) for a fluid, characterized in that the outlet openings (28) are arranged and aligned in such a way as to to direct the fluid exiting the outlet openings (28) to a radially inner side (30) of the end winding (16). Electric machine (100) after claim 1 , characterized in that the outlet openings (28), preferably the reaction turbine (23), are arranged in a plane comprising the end winding (16) perpendicular to an axis of rotation of the rotor (11), so that the outlet openings (28), preferably the reaction turbine ( 23), are arranged in an interior space (29) delimited radially by the end winding (16). Electric machine (100) after claim 1 or 2 , characterized in that the cooling device (24) comprises at least two reaction turbines (23). Electric machine (100) after claim 3 , characterized in that the at least two reaction turbines (23) are arranged on opposite end sides (14, 15) of the electrical machine and are designed for fluid cooling of a respective end winding (16) arranged on the respective end side (14, 15). Electrical machine (100) according to one of the preceding claims, characterized in that the electrical machine (100) has a housing with a housing cover (17), the housing cover (17) having a first bearing (21), in particular a roller or ball bearing (20) for the rotor shaft (12) and a second bearing (22), in particular a sliding bearing or a roller bearing, for the reaction turbine (23), the first bearing (21) and the second bearing (22) preferably being concentric with one another are arranged in one plane, more preferably on a pin (18) of the housing cover (17). Electric machine (100) after claim 5 , characterized in that the housing cover (17) has a supply line (25) for the fluid to the reaction turbine (23), and the reaction turbine (23) is connected to the housing cover (17) by means of a rotary feedthrough (26) for the fluid , wherein more preferably the rotary feedthrough (26) for cooling the first bearing (21) is formed. Electrical machine (100) according to one of claims 3 until 6 , characterized in that at least two reaction turbines (23) are arranged on the same end face (14, 15) of the electrical machine. Electric machine (100) after claim 7 , characterized in that a plurality of reaction turbines (23) are distributed evenly around the rotor shaft (12). Electric machine (100) after claim 7 or 8th , characterized in that in an intermediate space between the rotor shaft (12) and the reaction turbines (23), in particular between the journal (18) of the housing cover (17) supporting the rotor shaft (12) and the preferably arranged on the housing cover (17), Reaction turbines (23), vanes or baffles are arranged. Electrical machine (100) according to one of the preceding claims, characterized in that an outlet angle (α) of the fluid from the outlet openings (28) is designed to be adjustable.

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