DE102020200197B4 - Electrical machine with a conducting element - Google Patents

Abstract

Electrical machine comprising - a stator, - a rotor, the rotor being rotatable about an axis of rotation (13) relative to the stator and having a rotor shaft (1), the rotor shaft (1) being at least partially hollow and thus having a first channel (2) through which coolant can flow, the rotor shaft (1) having an axial opening (6) at a first shaft end (4) and at least one first radial opening (7) in its lateral surface, and at a second shaft end (5 ) has at least one second radial opening (8) in its lateral surface, and- a guide element (9), wherein the guide element (9) is fixedly connected at a first end (10) to a stationary component (12) and to a second end (11) extends at least partially through the axial opening (6) of the rotor shaft (1) into the first channel (2), the guide element (9) being hollow and thus forming a second channel (3) through which coolant can flow, wherein in the area of the At the end (11) of the guide element (9), a ring-like or sleeve-like first element (16) is fixedly arranged on an inner circumference of the rotor shaft (1), characterized in that the first element (16) has a guide geometry (17).

Description

field of invention

The present invention relates to an electrical machine comprising a stator, a rotor, the rotor being rotatable about an axis of rotation relative to the stator and having a rotor shaft, the rotor shaft being at least partially hollow and thus forming a first channel through which coolant can flow is, wherein the rotor shaft has an axial opening at a first shaft end and at least one first radial opening in its lateral surface and has at least one second radial opening at a second shaft end in its lateral surface, and a guide element.

State of the art

Electrical machines of the type mentioned above are used to convert electrical energy into mechanical energy and vice versa and are often used as a motor and/or generator in the field of automotive engineering.

Electrical machines include a fixed stator and a movable rotor, with the rotor in the most common design of an electrical machine being rotatably mounted 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 can include a rotor core and at least one rotor winding arranged on the rotor core.

Electrical machines generate heat during operation due to dielectric loss. A strong development of heat mainly occurs in the area of the stator winding and/or the rotor winding, in particular in the area of the respective winding overhangs. The result of this strong heating is an increase in the dielectric loss factor - even more electrical energy is converted into heat, which on the one hand causes a deterioration in the efficiency of the electrical machine and on the other hand negatively affects reliable operation of the electrical machine over its service life. Therefore, a cooling device is generally provided in drive arrangements with electrical machines, which cools the parts of the electrical machine to be cooled.

Conventional cooling for electrical machines use a circulating gaseous or liquid coolant. The coolant circulates, for example, in a housing of the electrical machine or in a rotor shaft designed as a hollow shaft, on which the rotor of the electrical machine is arranged. Due to its heat capacity, the coolant absorbs the heat and transports it away.

If the coolant is conducted through the rotor shaft, radial bores are often provided in the lateral surface of the rotor shaft in the end regions of the rotor shaft, via which in particular the end windings can be supplied with coolant. In this case, however, the feeding of the radial bores with coolant according to a fixed ratio is particularly difficult. Furthermore, the radial installation space of electrical machines is often limited and the rotor shaft, which is designed as a hollow shaft, can only have a very small inner diameter, which further impairs the efficiency of the cooling.

The generic document U.S. 6,897,581 B2 for example, discloses a high speed alternator having a main rotor and a main stator. The main rotor is mounted on a substantially hollow rotor shaft with supply ports for main rotor cooling extending through the rotor shaft. Main supply ports for main stator cooling are in fluid communication with the main supply ports for main rotor cooling - cooling liquid flows through the main rotor cooling port openings and the main stator cooling port openings. The main rotor and main stator cooling supply ports are configured to supply a spray of cooling liquid to the main rotor and main stator.

The document DE 10 2014 117 962 A1 discloses, for example, an electric drive system having an electric machine, the electric machine having a rotor and a stator, the rotor being rotatably received in the stator, and the rotor being formed with a cavity for the passage of a cooling medium. The electrical machine has a side flange in which at least one opening for the passage of the cooling medium is formed. According to the invention, an electrical control module is provided for controlling the electrical machine, the electrical control module being arranged on the side flange, and the electrical control module having a passage for the passage of the cooling medium which merges into the opening in the side flange.

The document DE 10 2016 225 523 A1 also discloses, for example, an electrical machine, a system for controlling the temperature of such an electrical machine and a method for operating such a system. In this case, the electrical machine has a rotor with at least one rotor bearing and a hollow through which a flow can flow space, the cavity being arranged radially around a rotor bearing of a rotor of the electrical machine, so that a heat transfer medium discharged through the cavity flows around the rotor bearing radially on the outside to control the temperature of the electrical machine.

Furthermore, in connection with the present facts, the document U.S. 2,524,269 A which discloses a pump having a hollow rotor, fluid being directed through the hollow rotor toward an impeller of the pump.

Summary of the Invention

It is an object of the invention to specify an electrical machine that allows efficiency-optimized operation, particularly in applications where installation space is critical, due to an improved cooling system.

This need can be met by the subject matter of the present invention according to the independent first claim. Advantageous embodiments of the present invention are described in the dependent claims.

According to the invention, the electrical machine includes a stator, a rotor and a conducting element.

According to the invention, the rotor can be rotated about an axis of rotation relative to the stator and has a rotor shaft.

According to the invention, the rotor shaft is at least partially hollow and thus forms a first channel through which coolant can flow. According to the invention, the rotor shaft has an axial opening at a first shaft end and at least one first radial opening in its lateral surface, and at least one second radial opening in its lateral surface at a second shaft end. The first passage of the rotor shaft is fluidly connected to an exterior of the rotor shaft via the first radial opening and the second radial opening.

In this context, a coolant is to be understood in particular as a liquid coolant, such as oil, for example. However, the use of another coolant, such as a gaseous coolant, is also conceivable.

According to the present invention, the vane is fixed at a first end, i.e. axially and rotationally fixed, to a stationary component and extends at a second end through the axial opening of the rotor shaft at least partially into the first passage.

The directional specification "axial" describes a direction along or parallel to the axis of rotation. The "radial" direction specification describes a direction normal to the axis of rotation.

According to the invention, the guide element is hollow and thus forms a second channel through which coolant can flow.

Coolant can thus be conducted into the first channel of the rapidly rotating rotor shaft via the guide element arranged in a rotationally fixed manner.

According to the invention, in the area of the second end of the guide element, namely at the transfer point between the second channel of the guide element and the first channel of the rotor shaft, a ring-like or sleeve-like first element is arranged firmly on an inner circumference of the rotor shaft. This first element prevents a portion of the coolant from leaking into the leakage gap.

Furthermore, according to the invention, the first element has a guide geometry. In this way, a distribution of the coolant in the direction of the first radial opening and the second radial opening can be controlled in a targeted manner in a geometric manner.

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

In a preferred embodiment variant, the diameter of the second channel of the guide element decreases over its axial extent, starting from the first end of the guide element. The second channel can preferably have a first section, a second section and a third section, the first section being formed between the first end of the guide element and the second section and the third section being formed between the second section (15) and the second End (11) of the guide element (9) forms. The second channel preferably has a first diameter in the area of the first section and a second diameter in the area of the third section, the first diameter being larger than the second diameter and the diameter of the second channel in the area of the second section starting from the first diameter of the first section of the second channel steadily decreases towards the second diameter of the third section of the second channel. Such a design of the second channel gives the guiding element a “nozzle function”, so that the coolant is accelerated and is conducted into the first channel via a smaller diameter. This reduces coolant leakage at the transfer point between the second channel of the vane and the first channel of the rotor shaft and ensures a sufficient supply of coolant to the second radial opening, particularly in the case of low coolant volume flows.

In a further preferred embodiment variant of the present invention, a sleeve-like second element is arranged in the first radial opening in such a way that it projects partially into the first channel. At low coolant volume flows - following the centrifugal force of the rotor - the coolant attaches to the inner circumference of the rotor shaft. The second element protruding into the first channel causes a substantial part of the coolant to “continue to flow” in the direction of the second shaft end of the rotor shaft and thus to the second radial opening.

In a further preferred embodiment variant of the present invention, a thread or at least a groove is formed at least partially on the inner circumference of the rotor shaft. In this way, the rotation of the rotor shaft can also promote the delivery of coolant.

A thread or at least one groove is preferably formed at least partially on an outer circumference of the guide element. In this way, the coolant leakage flows can be decelerated and more pressure loss can be built up in the leakage gap. Of course, this can also be represented by forming a thread or at least a groove on the inner circumference of the rotor shaft.

character list

• 1 zeigt eine schematische Darstellung einer ersten Ausführungsvariante einer Rotorwelle und eines Leitelements.
• 2 zeigt eine schematische Darstellung einer zweiten Ausführungsvariante einer Rotorwelle und eines Leitelements.
• 3 zeigt eine schematische Darstellung einer Ausführungsvariante einer Rotorwelle, eines Leitelements und eines ringartigen ersten Elements.
• 4 zeigt eine schematische Darstellung einer ersten Ausführungsvariante einer Rotorwelle, eines Leitelements und eines hülsenartigen ersten Elements.
• 5 zeigt eine schematische Darstellung einer zweiten Ausführungsvariante einer Rotorwelle, eines Leitelements und eines hülsenartigen ersten Elements.
• 6 zeigt eine schematische Darstellung einer dritten Ausführungsvariante einer Rotorwelle, eines Leitelements und eines hülsenartigen ersten Elements.
• 7a zeigt eine schematische Darstellung einer vierten Ausführungsvariante einer Rotorwelle, eines Leitelements und eines hülsenartigen ersten Elements.
• 7b zeigt eine Schnittdarstellung entlang der Schnittebene A-A gemäß 7a.
• 8 zeigt eine schematische Darstellung einer Ausführungsvariante einer Rotorwelle, eines Leitelements und eines hülsenartigen zweiten Elements.
• 9 zeigt eine schematische Darstellung einer Rotorwelle mit einem Gewinde in einem ersten Kanal.
• 10 zeigt eine schematische Darstellung eines Leitelements mit einem Gewinde an einem Außenumfang.

The invention is described below by way of example with reference to the drawings.

• 1 shows a schematic representation of a first embodiment variant of a rotor shaft and a guide element.
• 2 shows a schematic representation of a second embodiment variant of a rotor shaft and a guide element.
• 3 shows a schematic representation of an embodiment variant of a rotor shaft, a guide element and a ring-like first element.
• 4 shows a schematic representation of a first embodiment variant of a rotor shaft, a guide element and a sleeve-like first element.
• 5 shows a schematic representation of a second embodiment variant of a rotor shaft, a guide element and a sleeve-like first element.
• 6 shows a schematic representation of a third embodiment variant of a rotor shaft, a guide element and a sleeve-like first element.
• 7a shows a schematic representation of a fourth embodiment variant of a rotor shaft, a guide element and a sleeve-like first element.
• 7b shows a sectional view along the section plane AA according to FIG 7a .
• 8th shows a schematic representation of an embodiment variant of a rotor shaft, a guide element and a sleeve-like second element.
• 9 FIG. 12 shows a schematic representation of a rotor shaft with a thread in a first channel.
• 10 shows a schematic representation of a guide element with a thread on an outer circumference.

Detailed description of the invention

In 1 until 10 only a detailed view of an electrical machine according to the invention is shown schematically in each case.

An electrical machine according to the invention comprises a stator, a rotor and a conducting element 9. The rotor can be rotated about an axis of rotation 13 relative to the stator and has a rotor shaft 1.

The rotor shaft 1 is at least partially hollow and thus forms a first channel 2 through which coolant can flow. The rotor shaft 1 has an axial opening 6 at a first shaft end 4 and is closed at a second shaft end 5 ( 1 ).

The rotor shaft 1 has a plurality of first radial openings 7 in its lateral surface in the region of the first shaft end 4 and a plurality of second radial openings 8 in the region of the second shaft end 5 . The first channel 2 of the rotor shaft 1 is fluidly connected via the first radial openings 7 and the second radial openings 8 to an outer area of the rotor shaft 1, in particular to the end windings ( 1 ).

The direction “axial” describes a direction along or parallel to the axis of rotation 13. The direction “radial” describes a direction normal to the axis of rotation 13.

The guide element 9 is fixed at a first end 10, i.e. axially and rotationally fixed, with a fixed component 12, namely a housing 21 a transmission, and extends with a second end 11 through the axial opening 6 of the rotor shaft 1 partially into the first channel 2. The guide element 9 is hollow and thus forms a second channel 3 through which coolant can flow. Coolant can thus be conducted into the first channel 2 of the rapidly rotating rotor shaft 1 via the guide element 9 arranged in a rotationally fixed manner ( 1 ).

in the in 1 Schematically shown embodiment, the diameter of the second channel 3 of the guide element 9 over the axial extent of the guide element 9 is constant.

In 2 an embodiment variant is shown schematically in which the diameter of the second channel 3 of the guide element 9 is not constant over its axial extent. The second channel 3 has three sections, namely a first section 14, a second section 15 and a third section 26, the first section 14 being formed between the first end 10 of the guide element 9 and the second section 15 and the third section 26 is formed between the second section 15 and the second end 11 of the guide element 9 - the second section 15 is thus formed between the first section 14 and the third section 26. In the area of the first section 14, the second channel 3 of the guide element 9 has a first diameter. In the area of the third section 26, the second channel 3 of the guide element 9 has a second diameter, the second diameter being smaller than the first diameter. In the area of the second section 15, the diameter of the second channel 3 of the guide element 9 decreases steadily, starting from the first diameter of the second channel 3 in the area of the first section 14 towards the second diameter of the second channel 3 in the area of the third section 26. Such a configuration of the second channel 3 gives the guide element 9 a “nozzle function”, so that the coolant is accelerated and is conducted into the first channel 2 via a smaller diameter. This reduces the coolant leakage at the transfer point between the second channel 3 of the guide element 9 and the first channel 2 of the rotor shaft 1 and ensures a sufficient supply of the second radial opening 8 with coolant, particularly in the case of low coolant volume flows.

The guide element 9 itself has a stepped outer circumference, essentially following the diameter of the second channel 3, in order in particular to avoid incorrect assembly.

In 3 In the area of the second end 11 of the guide element 9, namely at the transfer point between the second channel 3 of the guide element 9 and the first channel 2 of the rotor shaft 1, a ring-like first element 16 is arranged firmly on an inner circumference of the rotor shaft 1, namely pressed in. The second channel 3 of the guide element 9 is designed with a constant diameter, but can also have varying diameters, such as in connection with the guide element 9 in 2 described, executed. The rotor shaft 1 has a shoulder 22 on its inner circumference. The annular first element 16 is pressed in the area of this shoulder 22 . The annular first member 16 prevents a portion of the coolant from leaking into a leakage gap 23 .

In 4 In the area of the second end 11 of the guide element 9, namely at the transfer point between the second channel 3 of the guide element 9 and the first channel 2 of the rotor shaft 1, a sleeve-like first element 16 is arranged firmly on an inner circumference of the rotor shaft 1, namely pressed in. The second channel 3 of the guide element 9 is also designed here with a constant diameter, but can also have a varying diameter according to the guide element 9 in 2 be executed. The rotor shaft 1 has the shoulder 22 on its inner circumference. The sleeve-shaped first element 16 is pressed in the area of this shoulder 22 . The sleeve-shaped first element 16 prevents a portion of the coolant from running into the leakage gap 23 .

In 5 a rotationally symmetrical, sleeve-shaped first element 16 is pressed into the rotor shaft 1 in the region of the second end 11 of the guide element 9 .

As a result, more coolant is directed to the second shaft end 5 of the rotor shaft 1 and the first radial openings 7 can be enlarged. The second channel 3 of the guide element 9 is designed with a constant diameter in the present exemplary embodiment, but can also have a varying diameter according to the guide element 9 in 2 be executed.
In 6 a rotationally symmetrical, sleeve-shaped first element 16 is partially pressed into the rotor shaft 1 in the region of the second end 11 of the guide element 9 . The first element 16 is designed in such a way that a first part 24 of the first element 16, namely that which is closer to the axial opening 6, is pressed into the rotor shaft and a second part 25 of the first element 16 is spaced apart from the inner circumference of the rotor shaft 1. substantially parallel to this partially extends into the first channel 2. The axial extent of the second part 25 of the first element 16 only ends at an axial point after, ie further away from the first shaft end 4, the axial point at which the first radial openings 7 are formed. That's how it works first element 16 as an extended guide element 9 and makes the coolant available in such a way that it is distributed to the first radial openings 7 and the second radial openings 8 purely under the control of centrifugal force.

In 7a and 7b a rotationally symmetrical sleeve-shaped first element 16 is pressed into the rotor shaft 1 in the region of the second end 11 of the guide element 9 , the basic design of which essentially corresponds to the sleeve-shaped first element 16 5 is equivalent to. This in 7 However, the first element 16 shown has a guiding geometry 17 . In this way, a division of the coolant in the direction of the first radial opening 7 and the second radial opening 8 can be controlled in a targeted manner in a geometric manner.

In 8th 1 shows a further embodiment variant in which a sleeve-like second element 18 is arranged in the first radial opening 7 in such a way that it partially protrudes into the first channel 2 . In the case of low coolant volume flows, the coolant adheres to the inner circumference of the rotor shaft 1--following the centrifugal force of the rotor. The second element 18 protruding into the first channel 2 causes a substantial part of the coolant to “continue to flow” in the direction of the second shaft end 5 of the rotor shaft 1 and thus to the second radial openings 18.

In 9 is a rotor shaft 1 on the inner circumference, namely in the first channel 2, partially a thread 19 is formed. Due to the formation of the thread, the conveyance of coolant can be additionally favored by the rotation of the rotor shaft 1 .

In 10 a guide element 9 with a constant diameter of the second channel 3 is shown, which has a thread 19 on its outer circumference. In this way, the coolant leakage flows can be decelerated and more pressure loss can be built up in the leakage gap 23 . Of course, this can also be represented by forming a thread 19 or at least a groove on the inner circumference of the rotor shaft 1 in the area of the leakage gap 23 .

Reference List

1

rotor shaft

2

First channel

3

second channel

4

First wave end

5

Second wave end

6

axial opening

7

First radial opening

8th

Second radial opening

9

guiding element

10

First ending

11

second ending

12

fixed component

13

axis of rotation

14

first section

15

second part

16

First item

17

guiding geometry

18

second item

19

thread

21

casing

22

paragraph

23

leakage gap

24

First part

25

Second part

26

Third section

Claims (6)

Electrical machine comprising - a stator, - a rotor, the rotor being rotatable about an axis of rotation (13) relative to the stator and having a rotor shaft (1), the rotor shaft (1) being at least partially hollow and thus having a first channel (2) through which coolant can flow, the rotor shaft (1) having an axial opening (6) at a first shaft end (4) and at least one first radial opening (7) in its lateral surface, and at a second shaft end (5 ) has at least one second radial opening (8) in its lateral surface, and - a guide element (9), the guide element (9) being firmly connected at a first end (10) to a stationary component (12) and to a second end (11) extends at least partially through the axial opening (6) of the rotor shaft (1) into the first channel (2), the guide element (9) being hollow and thus forming a second channel (3) through which coolant can flow, wherein in the area of second end (11) of the guide element (9), a ring-like or sleeve-like first element (16) is fixedly arranged on an inner circumference of the rotor shaft (1), characterized in that the first element (16) has a guide geometry (17). Electric machine after claim 1 , characterized in that the diameter of the second channel (3) decreases over its axial extent starting from the first end (10). Electric machine after claim 1 , characterized in that the second channel (3) has a first portion (14), a second portion (15) and a third portion (26), wherein the first portion (14) between the first end (10) of the guide member (9) and the second section (15) and the third section (26) is formed between the second section (15) and the second end (11) of the guide element (9), and the second channel (3) in the region of the first section (14) has a first diameter and in the area of the third section (26) has a second diameter, the first diameter being larger than the second diameter and the diameter of the second channel (3) in the area of the second section (15 ) steadily decreases from the first diameter to the second diameter. Electric machine according to one of Claims 1 until 3 , characterized in that in the first radial opening (7) a sleeve-like second element (18) is arranged such that it projects partially into the first channel (2). Electrical machine according to one of the preceding claims, characterized in that a thread (19) or at least a groove is formed at least partially on an inner circumference of the rotor shaft (1). Electrical machine according to one of the preceding claims, characterized in that a thread (19) or at least one groove is formed at least partially on an outer circumference of the guide element (9).

Images