GB2565258A

GB2565258A - Electric machine having a hollow rotor shaft

Info

Publication number: GB2565258A
Application number: GB1819371.4A
Authority: GB
Inventors: Voight Matthias; Krebs Jorg
Original assignee: Krebs & Aulich GmbH
Current assignee: Krebs & Aulich GmbH
Priority date: 2016-06-16
Filing date: 2017-05-17
Publication date: 2019-02-06
Anticipated expiration: 2037-05-17
Also published as: AT524997B1; GB2565258A9; WO2017215686A1; DE102016007328B4; AT524997A5; DE102016007328A1; GB201819371D0; GB2565258B

Abstract

The invention relates to an electric machine (1), designed as a motor and/or as a generator, comprising a housing (2), a stator (3) rotationally fixed to the housing (2), and a rotor shaft (5) arranged coaxially and radially within the stator (3), wherein the stator (3) and the rotor shaft (5) support electromagnetically effective components (4; 6), between which a hollow cylindrical air gap (7) is formed, wherein the rotor shaft (5) has a cylindrical inner space (8) which is closed at both axial ends thereof, wherein the rotor shaft (5) has at least one radially oriented inflow channel (20a, 20c) for introducing a cooling fluid into the inner space (8) as well as at least one radially oriented outflow channel (21a, 21c) for discharging the cooling fluid, and wherein the cooling fluid can be directed to the rotor shaft (5) via at least one inlet channel (13) in the housing (2), and away from same via at least one outlet channel (14) in the housing (2). In order to optimise the flowing of the cooling fluid into and/or out of the rotor shaft (5), according to the invention, at least one inflow channel (20a, 20c) and/or at least one outflow channel (21a, 21c) radially and transversely penetrates the wall of the rotor shaft (5) at a setting angle (a, c1, c2).

Description

Electric machine having a hollow rotor shaft

The invention relates to an electric machine, realized as a motor and/or as a generator, having a housing, a stator connected in a rotationally fixed manner to the housing, and a rotor shaft arranged coaxially and radially within the stator, in which the stator and the rotor shaft carry electromagnetically active components, between which a hollow cylindrical air gap is realized, in which the rotor shaft has a cylindrical inner space, which is closed at both axial ends thereof, in which the rotor shaft has at least one radially oriented inflow channel for introducing a cooling fluid into its inner space, and at least one radially oriented outflow channel for discharging the cooling fluid, and in which the cooling fluid can be guided to the rotor shaft via at least one intake channel in the housing, and away from the same via at least one discharge channel in the housing.

Such an electric machine may be integrated, for example, in a dynamometer or a vehicle test stand used to determine characteristic values of a vehicle or of drivetrain components. The rotor shaft is usually cooled by means of a gaseous cooling fluid, and the stator by means of a liquid cooling fluid, the latter being routed through cooling channels in the housing of the electric machine. Accordingly, for the purpose of cooing the rotor shaft, or the electromagnetically active components carried by the rotor shaft, cooling air is guided through an intake channel in the housing of the electric machine, via at least one radial inflow channel in the rotor shaft, into the cylindrical inner space thereof, and after flowing through same is routed away through at least one radial outflow channel in the rotor shaft, out of the latter. The thus heated cooling air can then be exhausted into the environment via the at least one discharge channel in the housing.

The at least one intake opening and the at least one discharge opening in the rotor shaft are realized as radial drilled holes, which are oriented perpendicularly to the longitudinal axis of the rotor shaft. Although, owing to this orientation of the inlet opening and the outlet opening, they are inexpensive to make in the production of such a rotor shaft, it is disadvantageous that, upon a rotation of the rotor shaft, in particular the admission of the cooling air into the cylindrical inner space of the rotor shaft is effected in a very disadvantageous manner from a fluidic perspective. Particularly in the case of very high rotor rotational speeds, for example 40000 revolutions per minute, a flow separation may occur at the at least one intake opening. The cooling air must therefore be guided with a comparatively high delivery pressure to the at least one intake opening of the rotor shaft, so that it can flow into the cylindrical inner space of the rotor shaft. The generation of a sufficiently high conveying pressure requires a compressor, the operation of which results in energy costs, which are to be reduced.

Against this background, the invention was based on the object of developing an electric machine, of the type stated at the outset, in such a manner that a gaseous cooling fluid can be guided into and through the cylindrical inner space of the rotor shaft with a comparatively small expenditure of energy.

This object is achieved by an electric machine having the features of claim 1. Advantageous developments are defined in the dependent claims.

Accordingly, the invention relates to an electric machine, realized as a motor and/or as a generator, having a housing, a stator connected in a rotationally fixed manner to the housing, and a rotor shaft arranged coaxially and radially within the stator, in which the stator and the rotor shaft carry electromagnetically active components, between which a hollow cylindrical air gap is realized, in which the rotor shaft has a cylindrical inner space, which is closed at both axial ends thereof, in which the rotor shaft has at least one radially oriented inflow channel for introducing a cooling fluid into its inner space, and at least one radially oriented outflow channel for discharging the cooling fluid, and in which the cooling fluid can be guided to the rotor shaft via at least one intake channel in the housing, and away from the same via at least one discharge channel in the housing.

To achieve the said object it is provided, in the case of this electric machine, that at least one inflow channel and/or at least one outflow channel passes radially and obliquely, at a pitch angle, through the wall of the rotor shaft.

The proposed orientation of the inflow channels and/or outflow channels of the rotor shaft enables the cooling fluid to flow more easily than before into the rotor shaft and to flow more easily than before back out of the latter since, owing to the inclination of the inflow channels and/or the outflow channels, they convey in a flu id ically effective manner. This is not achieved in the case of the inflow channels or outflow channels hitherto oriented perpendicularly in relation to the longitudinal axis of the rotor shaft, such that, in the case of these channels, the cooling fluid is guided through the rotor shaft merely because of a pressure gradient between the inflow channels and the outflow channels.

According to a first embodiment, it is provided that the radially outer inlet opening of the at least one inflow channel and/or the radially outer outlet opening of the at least one outflow channel points in the direction of rotation of the rotor shaft. An advantageous inlet or outlet of the cooling fluid into or out of the rotor shaft is thereby achieved.

According to an alternative embodiment, to achieve the same technical purpose it is provided that the radially outer inlet opening of the at least one inflow channel points in the direction of rotation of the rotor shaft, and that the radially outer outlet opening of the at least one outflow channel points contrary to the direction of rotation of the rotor shaft. A particularly fluidically favorable inlet or outlet of the cooling fluid into or out of the rotor shaft is thereby achieved.

The said oblique pitch and orientation of the inflow channels and/or outflow channels of the rotor shaft not only facilitate inflow of the cooling fluid into the cylindrical inner space of the rotor shaft, but also improve the outflow conditions for the cooling fluid out of the rotor shaft. This is mainly because, in the case of the technical solutions hitherto, the cooling fluid exited the rotor shaft only radially, which, owing to the rotation of the rotor shaft, resulted in a high degree of turbulence of the cooling fluid in an outlet-side annular space between the rotor shaft and the housing of the electric machine. Owing to the oblique pitch of the outflow channels of the rotor shaft proposed by the invention, a circular flow of the cooling medium, which has the same direction of rotation as the rotor shaft, can be generated in the outlet-side annular space between the rotor shaft and the housing. The deceleration of the outer surface of the rotor shaft caused by the cooling medium is therefore less than in the case of conventional electric machines of the generic type, which additionally increases their efficiency.

The outflow conditions can be further improved by an inlet opening of the outlet channel of the housing pointing in the direction of flow. Such an inlet opening of the outlet channel is accordingly oriented, not merely radially, but tangentially in relation to the outer surface of the rotor shaft.

According to another development of the invention, it is provided that the pitch angle of the at least one inflow channel and/or the at least one outflow channel of the rotor shaft in relation to the surface normal, on the radial outer side of the rotor shaft, in the region of the respective inflow channel or outflow channel, has an angle of from 2° to 88°, including the range limits. Angles of from 10° to 80° are preferred. Pitch angles of from 30° to 45° are especially fluidically favorable.

It may further be provided that at least one inflow channel and/or at least one outflow channel of the rotor shaft are oriented at right angles in relation to the longitudinal axis of the rotor shaft, which, in terms of manufacture, can be realized comparatively easily.

By contrast, however, it may also be provided that at least one inflow channel and/or at least one outflow channel of the rotor shaft are oriented at an angle of from 5° to 85°, including the range limits, in relation to the longitudinal axis of the rotor shaft. Angles of from 10° to 80° are preferred. Pitch angles of from 30° to 45° are especially fluidically favorable. As a result of this oblique orientation, in particular of the inflow channels in relation to the longitudinal axis of the rotor shaft, the cooling fluid, already as it flows into the cylindrical inner space of the rotor shaft, is forced into a helical flow that has the same direction of rotation as the rotor shaft. The rotor shaft rotates at a higher rotational speed than the flow of cooling fluid in the inner space of the rotor shaft, but since, already upon inflow, the direction of rotation is identical in the inner space of the rotor shaft, the flow of cooling fluid has a lesser decelerating effect upon the rotor shaft than in the case of a conventional, predominantly axial, flow dominated by a conveying pressure of a compressor for conveying the cooling fluid.

According to another development of an electric machine having the features of the invention, it is provided that the radially outwardly realized inlet opening of the at least one inflow channel is larger than the radially inwardly realized inlet opening thereof. The pressure of the cooling fluid is thereby increased as it flows through the inflow channel, such that the cooling fluid, after entering the cylindrical cavity of the rotor shaft, following a relatively large pressure gradient, moves to at least one outflow channel of the rotor shaft.

Further, it may be provided, on the outflow side of the rotor shaft, that the radially inwardly realized outlet opening of the at least one outflow channel is larger than the radially outwardly realized outlet opening thereof. An expansion of the cooling fluid, which drives the latter away from the rotor shaft and toward the outlet channel of the housing of the electric machine, is thereby effected at the radially outwardly realized outlet opening.

For the purpose of producing a different guiding effect, and thus to further improve the flow of the cooling fluid into the rotor shaft, it may be provided that, on the radial outer side of the rotor shaft, preferably immediately adjacent to the radially outer inlet opening of the at least one inflow channel, a guide element pointing radially outward is realized or fastened on the radial outer surface of the rotor shaft. This guide element may be in the form, for example, of a lip or ring. Owing to its design and arrangement, it guides the cooling fluid into the inflow channel.

In order to produce such a guiding effect also radially within the rotor shaft, it may be provided that, preferably immediately downstream after the radially inner outlet opening of the at least one outflow channel, a guide element pointing radially inward is realized or fastened on the radial inner side of the rotor shaft. This guide element, also, may be realized, for example, as a lip or ring.

Upon a rotation of the rotor shaft, the said guide elements on the radial outer side and radial inner side of the rotor shaft cause cooling fluid that is present immediately adjacent to the associated openings in the rotor shaft to be deflected into the radially outer inlet opening of the at least one inflow channel, or into the radially inner outlet opening of the at least one outflow channel. A pumping action, which drives the cooling fluid through the rotor shaft, is thereby generated.

In order to ensure that the cooling fluid flows with little resistance within the rotor shaft, it may be provided, according to another development of the invention, that at least one guide device is arranged or realized on the radial inner side of the rotor shaft, extending at least largely parallel to the longitudinal axis thereof. In the simplest case, this guide device consists of a guide plate extending parallel to the longitudinal axis.

The guide device, however, may also be formed by at least one convolute web that is realized or fastened on the inner side of the rotor shaft, extends radially inward, and has a helical geometry.

For the purpose of further improving the inflow and outflow conditions for the cooling fluid, it may be provided that at least one inflow channel and/or at least one outflow channel passes with a convolute course through the wall of the rotor shaft, radially and in the circumferential direction, wherein the size-wise extent of this convolute inflow channel or convolute outflow channel is at least twice as great as the radial extent of the same.

The invention is explained in greater detail in the following on the basis of a plurality of exemplary embodiments represented in the appended drawing. There are shown in the latter:

Fig. 1 a schematic longitudinal section through an electric machine having the features of the invention,

Fig. 2 a first cross section A-A through the rotor shaft according to Fig. 1,

Fig. 3 a second cross section B-B through the rotor shaft according to Fig. 1,

Fig. 4 an enlarged cross-sectional view of a circumferential portion of the rotor shaft according to Fig. 1 in the region of an oblique inflow channel,

Fig. 5 an enlarged cross-sectional view of a circumferential portion of the rotor shaft according to Fig. 1 in the region of an inflow channel realized in a convolute manner, Fig. 6 a schematic radial top view of a rotor shaft with an inflow channel and an outflow channel that are each oriented perpendicularly in relation to the longitudinal axis thereof,

Fig. 7 a schematic radial top view of a rotor shaft with an inflow channel and an outflow channel that are each oriented obliquely in relation to the longitudinal axis of the rotor shaft,

Fig. 8 a cross section A-A through the rotor shaft according to Fig. 1, with inflow channels that taper radially inward,

Fig. 9 a cross section B-B through the rotor shaft according to Fig. 1, with outflow channel that taper radially outward,

Fig. 10 an enlarged cross-sectional view of an inflow channel that tapers radially inward, and of a prism-shaped guide element on the outer side of the rotor shaft, and Fig. 11 an enlarged cross-sectional view of an outflow channel that tapers radially outward, and of an annular guide element on the inner side of the rotor shaft.

The electric machine 1 represented in Fig. 1 is realized as an electric motor. It has a largely hollow cylindrical housing 2, which is closed, at both of its axial ends, by a respective housing cover 24. Fastened in the housing 2 is a stator 3 that extends coaxially with the longitudinal axis 17 of the electric machine 1. Arranged radially within the stator 3 is a rotor shaft 5, which is supported in a rotatable manner in the housing 2 via at least two rolling bearings 11, 12. The stator 3 and the rotor shaft 5 are provided with electromagnetically active components 4, 6 that are spaced apart from each other radially by a cylindrical air gap 7. The electromagnetically active components 4, 6 are realized as laminated cores, windings and/or permanent magnets, the structure and functioning of which are known to persons skilled in the art and are not relevant in connection with the invention. They have therefore not been illustrated and described in detail. Realized in the housing 2, for the purpose of cooling the stator 3, is at least one cooling-water channel 18, through which a cooling-waterflow 19 is guided.

The rotor shaft 5 is realized as a hollow shaft, which is closed at its axial ends by a respective rotor-shaft cover 9. For this purpose, the rotor-shaft covers 9 are fastened to the rotor shaft 5 by means of screws 10. As a result, the rotor shaft 5 has a largely closed cylindrical inner space 8, having a radial inner side 34, by which a cooling fluid, in the form of cooling air, can be guided. This cooling air is supplied to the rotor shaft 5 through a radial intake channel 13 in the housing 2 and, after passing through this intake channel 13, goes into an inlet-side annular space 15 that is realized between the housing 2, the rotor shaft 5, the inlet-side rolling bearing 11 and the electromagnetically active components 4, 6 of the electric machine 1.

For the purpose of supplying the cooling air to, and removing it from, the inner space 8 of the rotor shaft 5, the latter has four inflow channels 20a, 20b, 20c, 20d and four outflow channels 21a, 21 b, 21c, 21 d, which extend obliquely through the wall of the rotor shaft 5 from radially outside to radially inside. This is shown clearly in Figures 2 to 5.

In order to achieve inflow conditions for the cooling air that are fluidically particularly advantageous, it is provided that the radially outer inlet openings 31 of the inflow channels 20a, 20b, 20c, 20d; 20a’; 20a* and/or the radially outer outlet openings 32 of the outflow channels 21a, 21b, 21c, 21 d; 21a’; 21a* point in the direction of rotation 30 of the rotor shaft 5. As a result, the radially outer inlet openings 31 of the inflow channels and the radially outer outlet openings 32 of the outflow channels convey in a fluidically effective manner, such that a device delivering the cooling air has a comparatively low energy consumption. In connection with this, Fig. 1 shows the inflow direction 25 and the outflow direction 26 of the cooling air on the rotor shaft 5, while Figures 2 and 3 make clear that the inflowing cooling air divides into a plurality of inflowing sub-flows 25a, 25b, 25c, 25d, which flow into the inner space of the rotor shaft 5 through a respective associated inflow channel 20a, 20b, 20c, 20d. On the discharge side of the rotor shaft 5, the heated cooling air is divided into four outflowing sub-flows 26a, 26b, 26c, 26d, which exit the inner space 8 of the rotor shaft 5, through a respective associated outflow channel 21a, 21b, 21c, 21 d, in the direction of a discharge-side, second annular space 16. From there, the heated cooling air passes into the environment via a discharge channel 14 in the housing 2. The inlet opening 29 of the discharge channel 14 that is realized radially inwardly in the housing 2 preferably extends somewhat tangentially in relation to the radial outer side 33 of the rotor shaft 5.

It is made clear by Fig. 4 that the pitch angle a of the inflow channels 20a, 20b, 20c, 20d; 20a’; 20a* and/or of the outflow channels 21 a, 21 b, 21 c, 21 d; 21 a’; 21 a* has a value of from 2° to 88°, including the range limits, in relation to the surface normal 23 on the radial outer side of the rotor shaft 5, in the region of the respective inflow channel or outflow channel. In the example represented in Fig. 4, the pitch angle a is approximately 45° in relation to the surface normal 23, which stands perpendicularly, at an angle b = 90°, on the circular or slightly elliptical notional surface formed by the radially outer inlet opening 42.

In the case of the embodiment of the rotor shaft 5 shown in Fig. 5, it is provided that at least one inflow channel 20a* and/or at least one outflow channel 21a* passes with a convolute course through the wall the rotor shaft, radially and in the circumferential direction. In this case, the size-wise extent 27 of this convolute inflow channel 20a* or convolute outflow channel 20a*, is at least twice as great as the radial extent 28 of the inflow channel 20a* or outflow channel 20a* The inflow direction and the twist of the cooling air to be introduced into, or removed from, the inner space 8 of the rotor shaft 5 can be set particularly effectively by means of the convolute course of the inflow channel 20a* or outflow channel 20a*.

Fig. 6 shows that at least one inflow channel 20a and at least one outflow channel 21a of the rotor shaft 5 can be oriented at right angles c1 in relation to the longitudinal axis 17 of the rotor shaft 5. In terms of manufacture, it is comparatively easy to produce such inflow channels and outflow channels on the rotor shaft 5. In order to impart an effective twist to the cooling air to be guided through the inner space 8 of the rotor shaft 5, in the direction of conveyance of the cooling air, it may be provided, according to the variant represented in Fig. 7, that at least one inflow channel 20a' and/or at least one outflow channel 21a' of the rotor shaft 5 is oriented at an angle c2 of from 5° to 85° in relation to the longitudinal axis 17 of the rotor shaft

5. In the exemplary embodiment represented the angle c2 is approximately 75°.

Figures 8 to 11 show developments in the case of an electric machine 1, or the rotor shaft 5 thereof, realized according to the invention, by means of which the inflow of the cooling fluid into the rotor shaft 5, the transport of the cooling fluid within the rotor shaft, and the exiting of the rotor shaft are influenced in an advantageous manner.

It is thus provided, firstly, that the radially outer inlet opening 43 of the inflow channels 40a, 40b, 40c, 40d in each case points in the direction of rotation 30 of the rotor shaft 5, and that the radially outer outlet opening 45 of the outflow channels 41a, 41b, 41c, 41 d in each case points contrary to the direction of rotation 30 of the rotor shaft 5. Upon rotation of the rotor shaft 5, the cooling fluid is thereby forcibly conveyed into the inflow channels 40a, 40b, 40c, 40d and, in the region of the outflow channels 41 a, 41 b, 41 c, 41 d, is sucked out of the latter. In the figures, the inflow direction 25 and the outflow direction 26 of the cooling fluid are indicated by flow arrows.

Figures 8 and 9, but in particular the detail views of Figures 10 and 11, additionally show that, according to another embodiment, the inflow channels 40a, 40b, 40c, 40d and the outflow channels 41a, 41b, 41c, 41 d do not have a constant flow cross section, but have a larger inlet opening on the flow inlet side than on the flow outlet side. Thus, it is shown clearly by Fig. 10 that, in the case of the exemplarily represented inflow channel 40b, its radially outer inlet opening 43 is larger than its radially inner inlet opening 42. As a result, cooling fluid flowing into the inflow channel 40b is compressed somewhat along its inflow direction 25, with pressure being increased. The outlet of the cooling fluid from the cylindrical cavity 8 of the rotor shaft 5 is effected, inter alia, via the outflow channel 41 represented in Fig. 10, the radially inner outlet opening 44 of which is larger than its radially outer outlet opening 45. The cooling fluid in this case follows the outflow direction 26. As a result of the described geometry of the outflow channel 41 b and of the likewise realized further outflow channels 41a, 41c, 41 d, the cooling fluid is compressed further as it exits the rotor shaft 5. As it is outlet from the respective outflow channel 41 a, 41 b, 41 c, 41 d, the cooling fluid expands and is thereby discharged away from the rotor shaft 5, specifically toward the discharge channel 14 in the housing 2 of the electric machine 1, which acts as a pressure sink.

For the purpose of further improving the inflow and the outflow of the cooling fluid into and out of the rotor shaft 5, guide elements 50, 52 are fastened or realized on the radial outer side 33 and/or on the radial inner side 34 of the rotor shaft 5, as shown by Figures 10 and 11. In the case of the exemplary embodiment shown in Fig. 10, an annular guide element 50, which is approximately prism-shaped in cross section, is fastened immediately adjacent to the radially outer inlet opening 43 of the inflow channel 40b. In the case of the exemplary embodiment according to Fig. 11, the guide element 52 is formed by a ring, which is circular in cross section and which is inserted in a receiving groove of the rotor shaft 5, not denoted further, downstream immediately after the radially inner outlet opening 44 of the outflow channel 41 a. For the cooling fluid present there, these guide elements 50, 52 form a flow resistance that causes the cooling fluid to flow into the respectively associated inflow channel 40b or outflow channel 41 b.

Finally, Figures 8 and 9 show that guide device 55, 56, 57, 58, which, in the exemplary embodiment represented, extend parallel to the longitudinal axis 17 of the rotor shaft 5, may be arranged or realized on the radial inner side 34 of the rotor shaft 5. These guide devices 55, 56, 57, 58 may be realized, for example, as guide plates, and result in a smooth, less turbulent flow of the cooling fluid through the rotor shaft 5. The guide devices may also be formed by one or more webs, pointing radially inward, which are arranged or realized on the inner side 34 of the rotor shaft 5, and which have a helical geometry.

All of the features stated in the above description of the figures, in the claims and in the preamble to the description can be applied and used both singly and in any combination with one another. The invention is thus not limited to the feature combinations that are described and claimed, but rather all feature combinations are to be regarded as having been disclosed.

List of references electric machine housing stator electromagnetically active components on the stator rotor shaft electromagnetically active components on the rotor shaft air gap inner space of the rotor shaft rotor shaft cover screws first rolling bearing second rolling bearing intake channel in the housing discharge channel in the housing first annular space second annular space longitudinal axis of the rotor shaft cooling-water channel cooling-waterflow first inflow channel of the rotor shaft second inflow channel of the rotor shaft third inflow channel of the rotor shaft fourth inflow channel of the rotor shaft inflow channel set obliquely to the longitudinal axis 17 convolute inflow channel first outflow channel of the rotor shaft second outflow channel of the rotor shaft third outflow channel of the rotor shaft fourth outflow channel of the rotor shaft first outflow channel set obliquely to the longitudinal axis of the rotor shaft

21a* convolute outflow channel surface normal in the region of the inflow channel or outflow channel housing cover inflow direction of a cooling fluid

25a first inflowing sub-flow of the cooling fluid

25b second inflowing sub-flow of the cooling fluid

25c third inflowing sub-flow of the cooling fluid

25d fourth inflowing sub-flow of the cooling fluid outflow direction of a cooling medium

26a first outflowing sub-flow of the cooling fluid

26b second outflowing sub-flow of the cooling fluid

26c third outflowing sub-flow of the cooling fluid

26d fourth outflowing sub-flow of the cooling fluid size-wise extent of the convolute inflow channel or outflow channel radial extent of the convolute inflow channel or outflow channel inlet opening of the discharge channel 14 in the housing direction of rotation of the rotor shaft radially outer inlet opening radially outer outlet opening radial outer side of the rotor shaft radial inner side of the rotor shaft

40a first tapering inflow channel

40b second tapering inflow channel

40c third tapering inflow channel

40d fourth tapering inflow channel a first tapering outflow channel b second tapering outflow channel c third tapering outflow channel d fourth tapering outflow channel radially inner inlet opening of the inflow channel 40b radially outer inlet opening of the inflow channel 40b radially inner outlet opening of the outflow channel 41 b radially outer outlet opening of the outflow channel 41 b guide element, pointing radially outward, on the rotor shaft guide element, pointing radially inward, on the rotor shaft first guide device within the rotor shaft second guide device within the rotor shaft third guide device within the rotor shaft fourth guide device within the rotor shaft

Claims

1. An electric machine (1), realized as a motor and/or as a generator, having a housing (2), a stator (3) connected in a rotationally fixed manner to the housing (2), and a rotor shaft (5) arranged coaxially and radially within the stator (3), in which the stator (3) and the rotor shaft (5) carry electromagnetically active components (4; 6), between which a hollow cylindrical air gap (7) is realized, in which the rotor shaft has a cylindrical inner space (8), which is closed at both axial ends thereof, in which the rotor shaft (5) has at least one radially oriented inflow channel (20a, 20b, 20c, 20d; 20a’; 20a*; 40a, 40b, 40c, 40d) for introducing a cooling fluid into its inner space (8), and at least one radially oriented outflow channel (21a, 21b, 21c, 21 d; 21a’; 21a*;

41 a, 41 b, 41 c, 41 d) for discharging the cooling fluid, and in which the cooling fluid can be guided to the rotor shaft (5) via at least one intake channel (13) in the housing (2), and away from the same via at least one discharge channel (14) in the housing (2), characterized in that at least one inflow channel (20a, 20b, 20c, 20d; 20a’; 20a*; 40a, 40b, 40c, 40d) and/or at least one outflow channel (21a, 21b, 21c, 21 d; 21a’; 21a*; 41 a, 41 b, 41 c, 41 d) passes radially and obliquely, at a pitch angle (a, c1, c2), through the wall of the rotor shaft (5).

2. The electric machine as claimed in claim 1, characterized in that the radially outer inlet opening (31) of the at least one inflow channel (20a, 20b, 20c, 20d; 20a’; 20a*) and/or the radially outer outlet opening (32) of the at least one outflow channel (21a, 21 b, 21 c, 21 d; 21 a’; 21 a*) points in the direction of rotation (30) of the rotor shaft (5).

3. The electric machine as claimed in claim 1, characterized in that the radially outer inlet opening (43) of the at least one inflow channel (40a, 40b, 40c, 40d) points in the direction of rotation (30) of the rotor shaft (5), and that the radially outer outlet opening (45) of the at least one outflow channel (41a, 41b, 41c, 41 d) points contrary to the direction of rotation (30) of the rotor shaft (5).

4. The electric machine as claimed in any one of claims 1 to 3, characterized in that the pitch angle (a) of the at least one inflow channel (20a, 20b, 20c, 20d; 20a’; 20a* 40a, 40b, 40c, 40d) and/or the at least one outflow channel (21a, 21b, 21c, 21 d; 21a’; 21a* 41a, 41b, 41c, 41 d) in relation to the surface normal (23), on the radial outer side (33) of the rotor shaft (5), in the region of the respective inflow channel or outflow channel, has an angle of from 2° to 88°, including the range limits.

5. The electric machine as claimed in any one of claims 1 to 4, characterized in that at least one inflow channel (20a) and/or at least one outflow channel (21a) of the rotor shaft (5) is oriented at right angles (c1) in relation to the longitudinal axis (17) of the rotor shaft (5).

6. The electric machine as claimed in any one of claims 1 to 5, characterized in that at least one inflow channel (20a1) and/or at least one outflow channel (21a1) of the rotor shaft (5) is oriented at an angle (c2) of from 5° to 85°, including the range limits, in relation to the longitudinal axis (17) of the rotor shaft (5).

7. The electric machine as claimed in either one of claims 1 and 6, characterized in that the at least one inflow channel (20a*) and/or at least one outflow channel (21a*) passes with a convolute course through the wall of the rotor shaft (5), radially and in the circumferential direction, wherein the size-wise extent (27) of this convolute inflow channel (20a*) or convolute outflow channel (21a*) is at least twice as great as the radial extent (28) of the same.

8. The electric machine as claimed in either one of claims 1 and 7, characterized in that the radially outwardly realized inlet opening (43) of the at least one inflow channel (40a, 40b, 40c, 40d) is larger than the radially inwardly realized inlet opening (42) thereof.

9. The electric machine as claimed in either one of claims 1 and 8, characterized in that the radially inwardly realized outlet opening (44) of the at least one outflow channel (41 a, 41 b, 41 c, 41 d) is larger than the radially outwardly realized outlet opening (45) thereof.

10. The electric machine as claimed in either one of claims 1 and 9, characterized in that, adjacent to the radially outer inlet opening (43) of the at least one inflow channel (40a, 40b, 40c, 40d), a guide element (50) pointing radially outward is realized or fastened on the radial outer side (33) of the rotor shaft (5).

11. The electric machine as claimed in any one of claims 1 and 10, characterized in that, immediately downstream after the radially inner outlet opening (44) of the at least one outflow channel (41a, 41b, 41c, 41 d), a guide element (52) pointing radially inward is realized or fastened on the inner side (34) of the rotor shaft (5).

12. The electric machine as claimed in either one of claims 1 and 11, characterized in that at least one guide device (55, 56, 57, 58) is arranged or realized on the radial inner side (33) of the rotor shaft (5), extending parallel to the longitudinal axis (17) thereof.

13. The electric machine as claimed in either one of claims 1 and 11, characterized in that a guide device (55, 56, 57, 58) having at least one helical web extending radially inward is arranged or realized on the radial inner side (33) of the rotor shaft (5).

14. The electric machine as claimed in either one of claims 1 and 13, characterized in that the inlet opening (29) of the discharge channel (14) in the housing (2) is oriented tangentially in relation to the radial outer side (33) of the rotor shaft (5).