DE102021134614A1 - Rotor for an electric machine with coolant flow barriers - Google Patents

Abstract

Rotor (1, 22, 28) for an electrical machine (38), comprising: a rotor shaft (3, 23, 29), a laminated core (2) arranged on the rotor shaft (3, 23, 29) and formed from stacked electrical laminations, Teeth which protrude radially outwards from the electrical laminations, a first end plate (4) arranged on one axial side of the laminated core (2) with radial projections (6) arranged along its circumference, a second end plate arranged on the opposite axial side of the laminated core (2). (5) having radial projections (7) arranged along its circumference, a plurality of rotor windings (8) each wound around a projection (6) of the first end plate (4) and an axially opposite projection (7) of the second end plate (5). , a first pot-shaped end cap (9), a second pot-shaped end cap (10), a cooling channel (12, 30) for a coolant which runs axially in the rotor shaft (3, 23, 29) and branches off radially into a first cavity (13). , a first flow barrier (15, 24, 34) arranged in the first cavity (13), a plurality of axially extending cooling channels formed in gaps between adjacent rotor windings (8), a second cavity (16), a second flow barrier (18, 25, 35 ) delimiting the second cavity (16) in the circumferential direction, the second cavity (16) being connected to two of the cooling channels formed in the gaps between adjacent rotor windings (8).

Description

The invention relates to a rotor for an electric machine, an electric machine with a rotor and a vehicle with an electric machine.

The rotor has a rotor shaft and a laminated core formed from stacked electrical laminations and arranged on the rotor shaft. The rotor belongs together with a stator to an electrical machine.

Electric machines of this type are increasingly being used in electrically powered vehicles and hybrid vehicles, primarily as an electric motor for driving a wheel or an axle of such a vehicle.

Such an electric motor is usually mechanically coupled to a gear for speed adjustment. In addition, the electric motor is usually electrically coupled to an inverter, which generates an AC voltage for the operation of the electric motor, for example a polyphase AC voltage, from a DC voltage supplied by a battery.

It is also possible to operate an electric machine with such a rotor as a generator for recuperating kinetic energy of a vehicle. For this purpose, the kinetic energy is first converted into electrical energy and then into chemical energy from a vehicle battery.

In a certain type of electrically excited synchronous motor (EESM), the rotor has rotor windings which are supplied with direct current in order to generate an exciting magnetic field. If a rotating field is generated with the stator windings of an associated stator, this causes a force to act on the rotor, so that it rotates synchronously with the rotating field of the stator.

However, the rotor windings are heated up considerably in the process, so that cooling is required. The cooling can take place, for example, by spraying liquid coolant, for example oil, onto the axial sides of the rotor. However, this type of cooling only works superficially and is therefore not very effective.

The invention is therefore based on the object of specifying a rotor for an electrical machine which can be better cooled during operation.

To solve this problem, a rotor with the features of claim 1 is provided.

The rotor according to the invention comprises a laminated core arranged on the rotor shaft and formed from stacked electrical laminations, as well as teeth which protrude radially outwards from the electrical laminations, a first end plate arranged on one axial side of the laminated core with radial projections arranged along its circumference, one on the opposite axial side a second end plate arranged in the laminated core with radial projections arranged along its circumference, a plurality of rotor windings which are each wound around a projection of the first end plate and an axially opposite projection of the second end plate, a first cup-shaped end cap which axially covers the first end plate, a second cup-shaped end cap End cap which covers the second end plate axially, a cooling channel for a coolant which runs axially in the rotor shaft and branches off radially into a first cavity which is delimited by the first end plate and the first pot-shaped end cap, a first flow barrier which is arranged in the first cavity, circumferentially bounding the first cavity, a plurality of axially extending cooling passages formed in gaps between adjacent rotor windings, a second cavity located on the axial side opposite the first cavity and bounded by the second end plate and the second cup-shaped end cap, and one in the second flow barrier arranged in the second cavity, which delimits the second cavity in the circumferential direction, wherein the second cavity delimited by the second flow barrier is connected to two of the axially extending cooling channels formed in the gaps between adjacent rotor windings and enabling a direction reversal of the coolant.

The invention is based on the finding that improved cooling of the rotor windings can be achieved if the coolant flows from one axial side of the rotor through the axial cooling channels to the opposite axial side due to the first and second flow barriers, with the flow barriers causing the coolant to reverse direction . The coolant thus first flows along the axial direction past the rotor windings, after a direction reversal it flows in the opposite axial direction past other rotor windings. The first and second flow barriers lengthen the path covered by the coolant as it flows through the rotor, so that it can absorb more heat and dissipate it from the rotor windings. In comparison to a conventional rotor, in which only coolant is sprayed onto the axial sides, the rotor according to the invention can be cooled significantly better and more homogeneously.

The electric machine can, for example, be an electrically excited synchronous machine act motor (EESM). The endplate projections of an endplate, which are also referred to as "plate extensions", can be arranged along the perimeter of the endplate. They are used, among other things, to hold the rotor windings in a specific position. The core protrusions of the core are also referred to as "teeth".

A preferred embodiment of the invention provides that the first flow barrier arranged in the first cavity delimits at least one further section of the first cavity, which is connected to two of the cooling channels formed in the gaps between adjacent rotor windings and running axially and enabling a direction reversal of the coolant. Analogously, the second flow barrier arranged in the second cavity can also delimit at least one further section of the second cavity, which is connected to two of the axially running cooling channels formed in the gaps between adjacent rotor windings and enabling a direction reversal of the coolant.

By dividing both the first cavity and the second cavity into two or more sections, the direction of the coolant can be reversed several times. Accordingly, a meandering coolant path can be formed, in which the coolant changes direction several times on its way through the rotor windings and is heated when passing through the rotor windings. The cooling of the rotor according to the invention is therefore particularly efficient.

In the rotor according to the invention, it can be provided that the first flow barrier and/or the second flow barrier has/have arms that extend outward in a star shape. These arms delimit the individual sections of the first cavity or the second cavity. Flow barriers of this type can be produced easily and are characterized by a low mass.

A preferred development of the invention provides that the cooling duct which opens radially from the rotor shaft into the first cavity is connected to a plurality of axially running cooling ducts and the first and second flow barriers are each shaped in such a way that the coolant reverses its flow direction when passing through a flow barrier. In this configuration, two or more separate cooling channels are formed through which coolant can flow at the same time. Accordingly, the mass flow of the coolant is increased. The separate cooling channels are designed in such a way that the direction of the coolant reverses through the flow barriers.

In the rotor according to the invention, it can also be provided that the first or the second pot-shaped end cap has an outlet for coolant. Coolant thus passes via the hollow rotor shaft into the first cavity and along the rotor windings into the second cavity, with the direction of flow of the coolant being reversed several times, if necessary. The coolant then leaves the rotor via the outlet in the first or second cup-shaped end cap. It is also possible that both cup-shaped end caps each have an outlet. If several separate cooling ducts open into a pot-shaped end cap, a separate outlet can also be provided for each cooling duct.

A variant of the rotor according to the invention provides that a second cooling duct branches off radially from the cooling duct running axially in the rotor shaft into the second cavity, which is connected to one of the cooling ducts running axially formed in the gaps between adjacent rotor windings, creating a second parallel coolant path is formed. In this configuration, the coolant is both supplied and removed via the rotor shaft. For this purpose, the rotor shaft can have two cooling ducts arranged next to one another or two cooling ducts arranged concentrically to one another.

In addition, the invention relates to an electrical machine with a rotor of the type described and a stator which surrounds the rotor. The rotor can rotate relative to the stator. The stator can have a further laminated core (stator core), which is formed from stacked electrical laminations. In addition, the stator can have windings of electrical conductors, for example in the form of coil windings or flat wire windings.

Furthermore, the invention relates to a vehicle with such an electric machine, which is provided for driving the vehicle. In particular, the machine can drive a wheel or an axle of the vehicle.

• 1 eine geschnittene Seitenansicht eines erfindungsgemäßen Rotors gemäß einem ersten Ausführungsbeispiel;
• 2 einen Schnitt entlang der Linie II-II von 1,
• 3 einen Schnitt entlang der Linie III-III von 1,
• 4 eine geschnittene Seitenansicht eines erfindungsgemäßen Rotors gemäß einem zweiten Ausführungsbeispiel;
• 5 einen Schnitt entlang der Linie V-V von 4,
• 6 einen Schnitt entlang der Linie VI-VI von 4,
• 7 eine geschnittene Seitenansicht eines erfindungsgemäßen Rotors gemäß einem dritten Ausführungsbeispiel;
• 8 einen Schnitt entlang der Linie VII-VII von 7,
• 9 einen Schnitt entlang der Linie IX-IX von 7, und
• 10 ein erfindungsgemäßes Fahrzeug mit einer elektrischen Maschine.

The invention is explained below using exemplary embodiments with reference to the figures. The figures are schematic representations and show:

• 1 a sectional side view of a rotor according to the invention according to a first embodiment;
• 2 a section along the line II-II of 1 ,
• 3 a section along line III-III of 1 ,
• 4 a sectional side view of a rotor according to the invention according to a second embodiment;
• 5 a section along the line VV of 4 ,
• 6 a section along line VI-VI of 4 ,
• 7 a sectional side view of a rotor according to the invention according to a third embodiment;
• 8th a section along the line VII-VII of 7 ,
• 9 a section along the line IX-IX of 7 , and
• 10 a vehicle according to the invention with an electric machine.

The 1 , 2 and 3 show a first embodiment of a rotor, wherein 1 a cut side view, 2 a section along the line II-II of 1 and 3 a section along line III-III of 1 shows.

the inside 1 The rotor 1 shown in a sectional side view is provided for an electrical machine that is used as an electric motor for driving a vehicle. The rotor 1 comprises a cylindrical laminated core 2 formed from stacked electrical laminations, which encloses a rotor shaft 3 in a positive and/or non-positive manner. The electrical sheets can be stamped parts of identical design. The laminated core 2 has a plurality of laminated core projections protruding radially outwards, which are also referred to as “teeth”. End sections of the laminated core projections are widened in the circumferential direction.

A first end plate 4 is located on a first axial side of the laminated core 2. There is a second end plate 5 on the opposite, second axial side of the laminated core 2. The end plates 4, 5 each have radial end plate projections 6, 7 (also called “plate extensions”), around which several rotor windings 8 are wound. The rotor windings 8 consist of lacquered copper wire. Both end plates 4, 5 each have an aluminum core which is overmoulded with plastic. Alternatively, the end plates could be made entirely of plastic.

A cup-shaped first end cap 9 covers the first end plate 4 . A cup-shaped second end cap 10 is located at the opposite axial end of the rotor 1 and covers the second end plate 5 .

In 2 and 3 , each showing axial views, it can be seen that a pole separator 11 is arranged in a first cavity 13 between two adjacent rotor windings 8, which closes the cavity 13 to the outside and causes the rotor windings 8 to maintain their position even at high speeds.

In the 1 The rotor shaft 3 shown has an axially running cooling channel 12 for a coolant. An oil, for example, is suitable as a coolant. This in 1 The right-hand end of the rotor shaft 3 branches off radially into the first cavity 13, which is delimited by an arm 14 of a first flow barrier 15. The first flow barrier 15 has a total of five arms 14 extending outward in a star shape. Four of the five arms 14 branch off from a ring of the first flow barrier 15 spaced from and surrounding the rotor shaft 3 . The first cavity 13 is also delimited by the first end plate 4 and in the axial direction by the first end cap 9 . Two adjacent arms 14 of the first flow barrier 15 each delimit a section in the first cavity 13.

Referring again to 2 it can be seen that coolant flows radially from the cooling channel 12 into the first cavity 13, which is located between two adjacent rotor windings 8 in the circumferential direction. The flow directions of the coolant are indicated by arrows. A "circle with a dot" indicates a flow direction of the coolant out of the plane of the drawing. A "circle with a cross" indicates a flow direction of the coolant into the plane of the drawing. The coolant flows along the first cavity 13 axially to the opposite, in 1 left end of rotor 1. In 3 it is shown that there is a second cavity 16 between adjacent rotor windings 8 . The second cavity 16 is delimited by two arms 17 of a second flow barrier 18 . The second flow barrier 18 has a total of four arms 17 which are arranged in the radial direction and form a cross. The section of the second cavity 16 delimited by the two adjacent arms 17 has, within the second cavity 16, an intermediate space 18 serving as an inlet for coolant between two rotor windings 8 and spaced circumferentially therefrom an intermediate space 19 serving as an outlet for coolant. Accordingly, coolant flowing axially from first cavity 13 through gap 19 into second cavity 16 may exit through gap 20 . The coolant then flows in turn axially to the opposite end of the rotor 1 and enters a further section of the first cavity 13 which is delimited by two arms 14 of the first flow barrier 15 . This process is repeated until the coolant passes through the rotor 1 leaves an outlet 21 formed in the first end plate 9.

The 4 , 5 and 6 show a second embodiment of a rotor 22, wherein 4 a cut side view, 5 a section along the line VV of 4 and 6 a section along line VI-VI of 4 shows. The rotor 22 is constructed similarly to the rotor 1 described in the first embodiment. Identical reference symbols are therefore used for matching components. A repeated description of identical components is omitted.

The hollow rotor shaft 23 has an axial cooling channel 12, which at the in 4 right end branches off into the first cavity 13, which is delimited by the end cap 9. In addition, the cooling channel 12 branches off at the in 4 left end into the second cavity 16, which is delimited by the end cap 10.

5 is a representation similar to 2 and shows a section along the line VV of 4 . Coolant passes radially from the axial cooling channel 12 into the first cavity 13, which is delimited by two arms of a star-shaped first flow barrier 24. The first flow barrier 24 divides the first cavity 13 into a total of five sections in the circumferential direction. From the in 5 In the uppermost section of the cavity 13, the coolant flows between two rotor windings 8 axially to the opposite end of the rotor 22.

6 is a view similar to 3 and shows a section along line VI-VI of FIG 4 . The coolant enters the second cavity 16, which is divided into a total of five sections by arms of a star-shaped second flow barrier 25. the inside 6 The upper portion of the second cavity 16 has an outlet 26 between adjacent rotor windings 8 such that coolant flows from the cavity 16 again along the axial direction to the opposite side of the rotor 22 .

At the same time, coolant flows from the cooling passage 12 within the rotor shaft 23 into an adjacent section 27 of the second cavity 16. From the section 27, the coolant flows in the axial direction to the opposite end and enters the first cavity 13.

Coolant entering either the first cavity 13 or the second cavity 16 from the rotor shaft 23 is redirected multiple times through the first flow barrier 24 and the second flow barrier 25, respectively, reversing the direction of flow until the coolant finally enters the first cavity 13 exits through outlet 21.

The 7 , 8th and 9 show a third embodiment of a rotor 28, which is constructed similarly to the rotor 1 described in the first embodiment. 7 shows a sectional side view, 8th a section along the line VII-VII of 7 and 9 a section along the line IX-IX of 7 .

the inside 7 The rotor 28 shown has a rotor shaft 29 with a first central cooling channel 30, which is located at the 7 has an inlet 31 on the left. In addition, the rotor shaft 29 has a second cooling channel 32 which surrounds the first central cooling channel 30 . The two cooling channels 30, 32 are thus arranged coaxially. The second cooling passage 32 has an outlet 33 located on the same axial side of the rotor shaft 29 as the inlet 31 .

In accordance with the previous exemplary embodiments, the first central cooling channel 30 opens out radially into the first cavity 13, in which a star-shaped first flow barrier 34 is located, as in FIG 8th is shown. In a section 35 formed by the first flow barrier 34 there is an outlet or gap between two adjacent rotor windings 8 so that coolant can flow axially to the opposite end of the rotor 28 .

9 shows that in 7 left end of the rotor 28. It can be seen that there is a star-shaped second flow barrier 35 in the second cavity 16, which divides the second cavity 16 into a total of four sections. In accordance with the above-described embodiments, the coolant thus flows multiple times between the first cavity 13 and the second cavity 16, each through different rotor windings 8. When the coolant flows through an in 8th Has reached section 36 shown in the first cavity 13, it flows through the rotor shaft 29, in which the outer cooling channel 32 is located. The coolant reaches the outlet 33 through the outer cooling channel 32.

10 shows a vehicle 37 with an electric machine 38 which is used to drive the vehicle 37 . The electrical machine 38 has a housing 39 in which the rotor 1 according to the invention and a stator 40 which surrounds the rotor 1 are accommodated.

Reference List

1

rotor

2

laminated core

3

rotor shaft

4

endplate

5

endplate

6

endplate protrusion

7

endplate protrusion

8th

rotor winding

9

end cap

10

end cap

11

pole separator

12

cooling channel

13

first cavity

14

poor

15

first flow barrier

16

second cavity

17

poor

18

second flow barrier

19

space

20

space

21

outlet

22

rotor

23

rotor shaft

24

first flow barrier

25

second flow barrier

26

outlet

27

Section

28

rotor

29

rotor shaft

30

first cooling channel

31

inlet

32

second cooling channel

33

outlet

34

first flow barrier

35

second flow barrier

36

Section

37

vehicle

38

electric machine

39

Housing

40

stator

Claims (11)

Rotor (1, 22, 28) for an electrical machine (38), comprising: - a rotor shaft (3, 23, 29), - a laminated core (2) arranged on the rotor shaft (3, 23, 29) and formed from stacked electrical laminations, - teeth that protrude radially outwards from the electrical laminations, - a first end plate (4) arranged on an axial side of the laminated core (2) with radial projections (6) arranged along its circumference, - a second end plate (5) arranged on the opposite axial side of the laminated core (2) with radial projections (7) arranged along its circumference, - a plurality of rotor windings (8) each wound around a projection (6) of the first end plate (4) and an axially opposite projection (7) of the second end plate (5), - a first pot-shaped end cap (9) which axially covers the first end plate (4), - a second cup-shaped end cap (10) which axially covers the second end plate (5), - A cooling duct (12, 30) for a coolant which runs axially in the rotor shaft (3, 23, 29) and branches off radially into a first cavity (13) which is formed by the first end plate (4) and the first pot-shaped end cap (9 ) is limited, - a first flow barrier (15, 24, 34) arranged in the first cavity (13) and delimiting the first cavity (13) in the circumferential direction, - a plurality of axially running cooling channels formed in gaps between adjacent rotor windings (8), - a second cavity (16) which is arranged on the axial side opposite the first cavity (13) and is delimited by the second end plate (5) and the second cup-shaped end cap (10), - a second flow barrier (18, 25, 35) arranged in the second cavity (16) and delimiting the second cavity (16) in the circumferential direction, the second cavity (16) delimited by the second flow barrier (18, 25, 35) is connected to two of the axially extending cooling ducts formed in the gaps between adjacent rotor windings (8) and enabling the coolant to reverse direction. rotor after claim 1 , wherein the first flow barrier (15, 24, 34) arranged in the first cavity (13) delimits at least one further section of the first cavity (13) which is connected to two of the axially extending, a reversal of direction of the coolant enabling cooling channels is connected. rotor after claim 1 or 2 , wherein the second flow barrier (18, 25, 35) arranged in the second cavity (16) delimits at least one further section of the second cavity (16) which is connected to two of the axially extending, a reversal of direction of the coolant enabling cooling channels is connected. Rotor according to one of the preceding claims, in which the first flow barrier (15, 24, 34) and/or the second flow barrier (18, 25, 35) has/have arms (14, 17) extending outwards in a star shape. Rotor according to one of the preceding claims, wherein the cooling channel which opens radially from the rotor shaft (3) into the first cavity (13) is connected to a plurality of cooling channels running axially and the first and the second flow barrier (15, 18, 24, 25, 34, 35) are each shaped in such a way that the coolant reverses its direction of flow when passing through a flow barrier (15, 18, 24, 25, 34, 35). Rotor according to one of the preceding claims, in which the first or the second cup-shaped end cap (9, 10) has an outlet (21) for coolant. Rotor according to one of the preceding claims, wherein a second cooling duct branches off radially from the cooling duct (12) running axially in the rotor shaft (23) into the second cavity (16), which is connected to one of the axially extending cooling channels is connected, whereby a second parallel coolant path is formed. rotor after claim 6 or 7 , wherein both cup-shaped end caps (9, 10) have an outlet (21) for coolant, each outlet (21) being associated with a coolant path. Rotor according to one of the preceding claims, wherein a second axially running cooling duct (32) for a coolant is formed in the rotor shaft (29), and the coolant can be supplied through the first axially running cooling duct (30) and through the second axially running cooling duct (32) is deductible. Electrical machine (38), with a rotor (1, 22, 28) according to one of Claims 1 until 9 and a stator (40) surrounding the rotor (1, 22, 28). Vehicle (37) with an electric machine (38). claim 10 , which is provided for driving the vehicle (37).

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