Rotor for an electric machine, having an improved cooling channel in the laminated rotor core

Abstract

The invention relates to a rotor (9) for an electric machine (1a.. 1c), comprising a rotor shaft (10) with an axial central bore (14) and a radial outlet opening (15) connected thereto. The rotor (9) additionally comprises a laminated rotor core (11) which is mounted on the rotor shaft (10) and has a plurality of rotor laminations (12, 12a, 12a', 12b) stacked axially one on top of the other and a plurality of rotor magnets (17.. 17b'), which are arranged, in the laminated rotor core (11), in a plurality of magnet groups (F1.. F3), each of which is associated with a different pole of the rotor (9). In the laminated rotor core (11), a radial cooling channel (16), the inlet opening of which lies opposite the outlet opening (15), runs through a plurality of cutouts (E1, E3, E5) in a first rotor lamination (12a, 12a') and at least one cutout (E2, E4, E6') in a second rotor lamination (12a, 12a') adjoining the first rotor lamination (12a, 12a'). The invention further relates to an electric machine (1) having such a rotor (9), to a vehicle (27) having such an electric machine (1), to a method for operating the electric machine (1), and to a method for producing such a rotor (9).

Description

[0001] Rotor for an electric machine with an improved cooling channel in the rotor lamination stack

[0002] TECHNICAL AREA

[0003] The invention relates to a rotor for an electric machine, comprising a rotor shaft with an axial central bore and a radial outlet opening connected to the central bore. The outlet opening from the axial central bore can, for example, be formed by a radial coolant bore. Furthermore, the rotor comprises a lamination stack mounted on the rotor shaft, with several axially stacked laminations, and several rotor magnets arranged in the lamination stack in multiple magnet groups, each magnet group being assigned to a different rotor pole of the rotor. Such a magnet group can comprise several rotor magnets or only one rotor magnet.Furthermore, the invention relates to an electric machine with a stator and a rotor of the type rotatably mounted therein, a vehicle with such an electric machine intended for propelling the vehicle, a method for operating such an electric machine, and a method for manufacturing a rotor of the type mentioned.

[0004] STATE OF THE ART

[0005] Such a rotor, such an electric machine, such a vehicle, such an operating method, and such a manufacturing process are all known from the prior art. A general problem is the heat generation in the rotor during operation of the electric machine. Particularly at high power densities, special design measures are necessary to prevent excessive heating of the rotor. This is especially important for magnetically excited rotors, as the magnetization of the permanent magnets used can be permanently impaired at high temperatures. For this purpose, it is known, for example, to provide cooling channels in the rotor lamination stack through which a coolant flows. However, the cooling effect of the known cooling channels is insufficient in many cases.

[0006] REVELATION OF THE INVENTION

[0007] One object of the invention is therefore to provide an improved rotor, an improved electric machine, an improved vehicle, an improved operating method for an electric machine, and an improved manufacturing method for a rotor. In particular, the cooling effect of the rotor is to be improved.

[0008] The object of the invention is solved with a rotor of the type mentioned at the outset, in which a radial cooling channel is provided in the rotor lamination stack, the inlet opening of which is opposite the outlet opening and which runs through several recesses in a first rotor lamination and at least one recess in a second rotor lamination adjacent to the first rotor lamination.

[0009] Instead of just one recess, the radial cooling channel can also run through several recesses in the second rotor plate.

[0010] In particular, at least one recess in the second rotor plate is offset from the recesses in the first rotor plate, and the recesses in the first and second rotor plates overlap each other. In other words, the radial cooling channel is bounded by recesses in the first and second rotor plates, with the recesses being arranged overlapping and radially offset from each other.

[0011] Accordingly, the first cooling channel also features at least one transition from the first rotor lamination to the second rotor lamination and, radially further out, a second transition from the second rotor lamination back to the first rotor lamination. This means that a coolant flow is directed from the first to the second rotor lamination and back again.

[0012] Accordingly, the radial cooling channel does not run exactly radially outwards, but rather runs in different rotor laminations in a main radial direction away from the radial outlet opening to the outside.

[0013] Two recesses arranged side by side in the first or second rotor lamination can generally be considered as one (elongated) recess with a connecting web. Several recesses arranged side by side in the first or second rotor lamination can therefore also be considered as one (elongated) recess with several connecting webs.

[0014] Furthermore, the problem of the invention is solved with an electric machine which has a stator and a rotor of the type mentioned which is rotatably mounted therein.

[0015] Furthermore, the problem of the invention is solved with a vehicle equipped with such an electric machine which is intended to propel the vehicle.

[0016] Furthermore, the object of the invention is solved by a method for operating an electric machine of the type mentioned, in which a coolant is directed from the central bore through the radial outlet opening into the radial cooling channel.

[0017] Finally, the object of the invention is achieved by a method for manufacturing a rotor of the type mentioned above, in which the rotor lamination stack is aligned with a pin inserted into an axial cooling channel. The proposed measures improve the cooling effect of a coolant, with several effects working synergistically. First, the cooling surface area is increased compared to known arrangements. Second, turbulence is generated, particularly during the transition from the first rotor lamination to the second and back again, thereby improving heat transfer from the rotor lamination stack to the coolant compared to a laminar or slightly turbulent boundary layer. Third, a homogeneous cooling effect can be achieved within the rotor lamination stack without requiring an excessive number of radial outlet openings from the central bore of the rotor shaft.A further advantage of creating the radial cooling channel is that it requires relatively little technical effort, as it only necessitates recesses in the rotor laminations. The radial cooling channel is formed almost "automatically" during the axial stacking of the rotor laminations to create the rotor lamination stack. This means that the improved cooling effect can be achieved economically. The proposed measures are particularly, but not exclusively, suitable for use in a permanent magnet rotor.

[0018] The electric machine may have a coolant port through which coolant can be introduced into the coolant bore. The coolant may also have a lubricating effect and can then be used to lubricate components of the electric machine.

[0019] It should be noted here that the radial cooling channel can generally be referred to as the "first" cooling channel and the axial cooling channel as the "second" cooling channel.

[0020] Further advantageous embodiments and developments of the invention will become apparent from the dependent claims and from the description in conjunction with the figures. In particular, the radial cooling channel can run between two groups of magnets. This allows the radial cooling channel to be provided in the rotor lamination stack without unduly weakening it mechanically. In the area of ​​the rotor magnets, magnet pockets are located in the rotor lamination stack to accommodate the rotor magnets. The centrifugal forces acting on the rotor lamination stack and the rotor magnets during operation of the electric machine, as well as the magnetic forces acting in the rotor lamination stack, must be absorbed by the rotor lamination stack.For example, the rotor magnets, viewed along the rotor axis, can be arranged in pairs in a V-shape within magnet pockets of the rotor lamination stack, with the radial cooling channel running at an angular position between two pairs of V-shaped rotor magnets. In this embodiment, at the root of the V-shaped arrangement (i.e., at its radially innermost point), there is a narrow section in the rotor lamination stack where relatively high tensile stresses prevail, as this is where centrifugal force, acting on the portion of the rotor lamination stack enclosed by the V-shaped arrangement, is transmitted. However, as proposed, the radial cooling channel is located between two groups or pairs of magnets and thus outside this area of ​​high mechanical stress. This prevents the rotor lamination stack from being further weakened by the radial cooling channel in this area.The cooling effect of the coolant can therefore be improved without significantly weakening the rotor lamination stack.

[0021] The radial cooling channel can, for example, exit radially from the rotor lamination stack or open into the axial (second) cooling channel formed by the rotor laminations. In the first case, the rotor lamination stack is cooled homogeneously across its entire radial area. In the second case, the coolant can be directed to the end faces of the rotor, allowing it to exit outside the air gap of the electric machine and thus avoiding frictional losses caused by coolant located in the air gap. In this context, it is advantageous if the axial cooling channel runs between two groups of magnets, spaced apart from the rotor magnets. This allows the rotor magnets to be encapsulated in the rotor lamination stack with a plastic material, for example, and thus permanently fixed. However, this is not the only conceivable option.It would also be conceivable for the cooling channel to open into a magnetic pocket for the rotor magnets, with the coolant then flowing in a cavity that remains next to the rotor magnets within the magnetic pocket. A separate axial cooling channel would then be unnecessary.

[0022] It is also conceivable that the axial (second) cooling channel opens into a third cooling channel exiting the rotor lamination stack, whereby the third cooling channel can exit the rotor lamination stack radially or axially. Advantageously, the point where the third cooling channel exits the rotor lamination stack is located radially further inward than the point where the radial cooling channel opens into the axial cooling channel. In this way, power losses caused by the oil exiting the rotor and resulting from the oil's acceleration in the tangential direction can be minimized. The division into the axial (second) cooling channel and the third cooling channel is not mandatory, and the section formed by the third cooling channel can also be considered part of the axial (second) cooling channel.

[0023] In another advantageous embodiment of the rotor, the axial cooling channel runs through the entire rotor lamination stack and is formed by overlapping or congruent recesses in all rotor laminations. The axial cooling channel can be used not only to conduct the coolant but also to align the rotor laminations or the rotor lamination stack during rotor manufacturing, particularly with respect to the rotor shaft. For this purpose, a tool pin is inserted into the axial cooling channel, and the rotor lamination stack is aligned with this pin during manufacturing. After the rotor lamination stack is manufactured, the pin is removed from the axial cooling channel. In this way, the axial cooling channel provides a dual benefit.It is also advantageous if the rotor shaft is guided through an axial through-opening in the rotor lamination stack, the inner diameter of which is larger at a first edge section than at a second edge section, with the outlet opening opposite the first edge section. In other words, a shaft bore has radially inwardly projecting extensions by means of which the rotor lamination stack is pressed onto the rotor shaft. Between these extensions are indentations where the press fit is exposed. This type of press fit is also referred to as a "partial press fit." In this embodiment, the angular position of the recesses for the radial cooling channel lies between the extensions. This ensures that any compressive stress resulting from the press fit is transferred within the rotor lamination to more stable areas and not to the comparatively fragile area of ​​the radial cooling channel.

[0024] It is also advantageous if the radial cooling channel runs through the cutouts of several first rotor laminations and / or the cutouts of several second rotor laminations. This allows the cross-section of the radial cooling channel to be easily increased. Furthermore, this improves the width-to-height ratio of the cross-section, resulting in a less shallow radial cooling channel and reduced flow resistance. For example, two first rotor laminations and two second rotor laminations can be arranged side by side. Alternatively, the radial cooling channel can run through the cutouts of a larger number of first rotor laminations and / or second rotor laminations to create a wider cooling channel.

[0025] It is also advantageous if the first and second rotor laminations are identical, with the first laminations being rotated relative to the second laminations about the rotor's axis of rotation. In this configuration, radially adjacent recesses at a first angular position of the first rotor lamination and at least one recess at a second angular position of the second rotor lamination are positioned so that they overlap, forming a continuous radial cooling channel. These measures simplify the manufacturing and storage of the rotor laminations. However, it is also conceivable that the first and second rotor laminations could be designed differently.

[0026] Furthermore, it is advantageous if the radial cooling channel is axially limited by two third rotor laminations. This allows the radial cooling channel to be closed off laterally. For example, the recesses forming the radial cooling channel in the third rotor lamination are omitted. However, the third rotor lamination can have recesses that form the axial cooling channel or are part of it.

[0027] It is advantageous if the rotor has an additional rotor lamination stack or lamination stack segments mounted on the rotor shaft, with both rotor lamination stacks or lamination stack segments being identical and twisted relative to each other around the axis of rotation. This allows for the production of skew or stepped rotors. This means that the magnetic poles extend across the rotor in a spiral shape or their path approximates a helix. This improves the rotational behavior of the rotor.

[0028] It should be added that although the radial (first) cooling channel, the axial (second) cooling channel, and the third cooling channel were each disclosed in the singular in the above description, the presented rotor lamination stack can also have multiple radial (first) cooling channels, multiple axial (second) cooling channels, and / or multiple third cooling channels. In particular, it is also conceivable that multiple radial cooling channels lead into one axial cooling channel, or that one axial cooling channel is part of several axial cooling channels.

[0029] BRIEF DESCRIPTION OF THE FIGURES Exemplary embodiments of the invention are shown in the accompanying schematic figures. They show:

[0030] Fig. 1 shows a half-section through an exemplary and schematically represented electrical machine;

[0031] Fig. 2 shows a detailed view of the rotor from Fig. 1 in the area of ​​one of the radial cooling channels;

[0032] Fig. 3 is similar to Fig. 2, but with several first and second rotor laminations arranged alternately;

[0033] Fig. 4 shows a top view of an exemplary rotor sheet with recesses for radial and axial cooling channels;

[0034] Fig. 5 as Fig. 4, but without recesses for radial cooling channels;

[0035] Fig. 6 shows a detailed view of a radial cooling channel, which is bounded by several first and second rotor laminations;

[0036] Fig. 7 shows a half section through an electric machine with a third axially exiting cooling channel;

[0037] Fig. 8 is similar to Fig. 7, but with a different design of the third cooling channel and

[0038] Fig. 9 shows an exemplary vehicle with an electric machine of the proposed type.

[0039] DETAILED DESCRIPTION OF THE INVENTION It is stated by way of introduction that identical parts in the different embodiments are provided with the same reference numerals or component designations, possibly with different indices. The disclosure of a component contained in the description can be applied analogously to another component with the same reference numeral or component designation. Furthermore, the positional indications chosen in the description, such as "top," "bottom," "back," "front," "side," and so on, refer to the figure directly described and illustrated and, in the event of a change in position, are to be applied analogously to the new position.

[0040] Fig. 1 shows a half-section through a schematically represented electric machine 1a with a stator housing 2, a first (front) end shield 3, and a second (rear) end shield 4, which together form a machine housing 5 or are at least part of it. It should be noted that the machine housing 5 can also have a different design and may include more or fewer parts than shown in Fig. 1. For example, the stator housing 2 could be cup-shaped, and the first or second end shield 3, 4 could be omitted.

[0041] Furthermore, the electric machine 1 comprises a stator 6 arranged in the stator housing 2, which has a stator lamination stack 7 (not shown in detail) and stator windings arranged in the stator lamination stack 7, of which, however, only the stator winding head 8 is visible in Fig. 1. In addition, the electric machine 1 comprises a rotor 9, which has a rotor shaft 10 and a rotor lamination stack 11 arranged on the rotor shaft 10, with several axially stacked rotor laminations 12.

[0042] The rotor shaft 10 is rotatably mounted about a rotor axis or stator axis A relative to the stator 6 by means of (rolling) bearings 13a, 13b. Specifically, the first bearing 13a is located in the first bearing shield 3 and the second bearing 13b in the second bearing shield 4. The rotor shaft 10 has a central bore 14 and several associated radial outlet openings 15, or radial coolant bores.

[0043] In the rotor lamination stack 11, several rotor magnets 17 are arranged in magnet pockets 18. Furthermore, several radial (first) cooling channels 16, formed by the rotor laminations 12, run within the rotor lamination stack 11, their inlet openings being opposite the outlet openings 15 in the rotor shaft 10. In this example, the radial cooling channels 16 open into an optional axial (second) cooling channel 19, which runs in the axial direction and finally opens into the interior B of the electric machine 1.

[0044] Figure 1 schematically shows a coolant nozzle 20 and a pump 21 (not belonging to the rotor 9), which is connected at its outlet to the coolant nozzle 20 and via this to the central bore 14. The pump 20 can pump coolant into the central bore 14, which is then directed through the radial outlet openings 15 into the radial cooling channels 16. This creates a coolant flow C, which passes through the central bore 14, the radial outlet openings 15, the radial cooling channels 16, and the axial cooling channel 19. Generally, several radial outlet openings 15, several radial cooling channels 16, and several axial cooling channels 19 can be provided, as is the case in the example shown in Figure 1.

[0045] Fig. 2 shows a detailed view of the rotor 9 in the area of ​​one of the radial cooling channels 16. The cooling channel 16 shown runs in different rotor laminations 12a, 12a' in a radial main direction away from the radial outlet opening 15 to the outside. Specifically, the radial cooling channel 16 runs through several recesses E1 ..E3 in the rotor laminations 12a, 12a', wherein, in the example shown, the recesses E1, E3 are arranged in a first rotor lamination 12a and the recess E2 is arranged in a second rotor lamination 12a' adjacent to the first rotor lamination 12a. The recess E2 in the second rotor lamination 12a' is offset from and overlaps the recesses E1, E3 in the first rotor lamination 12a. In other words, the first cooling channel 16 is bounded by recesses E1..E3 in the first and second rotor laminations 12a, 12a', wherein the recesses E1 ..E3 are arranged overlapping and radially offset from each other. In the figure shown.In the examples shown in Figures 1 and 2, the radial cooling channel 16 has a first transition D1 from the first rotor lamination 12a to the directly adjacent second rotor lamination 12a' and, further radially outward, a second transition D2 from the second rotor lamination 12a' back to the first rotor lamination 12a. This arrangement is purely exemplary, however, and more than two transitions D1, D2 are possible. The rotor lamination stack 11 also has an optional third rotor lamination 12b, which, however, does not have any recesses E1...E3 for the radial cooling channel 16 (but does have a recess for the axial cooling channel 19). The cooling channel 16 is thus bounded by two third rotor laminations 12b.

[0046] Fig. 3 shows an alternative embodiment of a cooling channel 16, which is similar to the embodiment shown in Fig. 2. However, unlike the embodiment according to Fig. 2, several first and second rotor laminations 12a, 12a' are arranged alternately here, resulting in a somewhat more complex course for the cooling channel 16. Because the cooling channel 16 runs through several rotor laminations 12a, 12a', a more homogeneous cooling effect is achieved than in the embodiment according to Fig. 2. The cooling channel 16 can also be bounded by two third rotor laminations 12b in the example shown in Fig. 3 (not shown).

[0047] Fig. 4 shows a top view of an exemplary rotor plate 12a. The rotor plate 12a has several radially adjacent recesses E1, E3, E5, and E6 at a first angular position a and several radially adjacent recesses E2, E4, and E6' at a second angular position a'. The angle oc + cc' lies between the two angular positions a and a'. If a first rotor plate 12a in the angular position shown in Fig. 4 and a second rotor plate 12a' are stacked one above the other, rotated by the angle oc + cc', so that the first angular position a of the first rotor plate 12a and the second angular position a' of the second rotor plate 12a' are aligned, the course of a cooling channel 16 shown in principle in Fig. 2 is created, which, in the case of the rotor plate 12a according to Fig. 4, has more than two transitions D1, D2.This means that in this case, the first rotor lamination 12a and the second rotor lamination 12a' are identical, with the first rotor lamination 12a being rotated relative to the second rotor lamination 12a' about the axis of rotation of the rotor 9. While this is advantageous because it simplifies the manufacturing and storage of the rotor laminations 12a and 12a', it would also be conceivable for the first rotor lamination 12a and the second rotor lamination 12a' to have different shapes.

[0048] It should be noted that several recesses E1, E3, E5 and E6 as well as E2, E4 and E6' arranged next to each other in the first or second rotor sheet 12a, 12a' can each also be considered as one (elongated) recess with webs 22 running between them.

[0049] The rotor lamination 12a shown in Fig. 4 also includes several magnet pockets 18 in which rotor magnets 17a..17b' are indicated. The rotor magnets 17a..17b' are arranged in several magnet groups F1..F3, each of which is assigned to a different magnetic rotor pole of the rotor 9. Specifically, in this example, the rotor magnets 17a..17b' are arranged in pairs in a V-shape in the magnet pockets 18 of the rotor lamination stack 11, as seen along the rotor axis A of the rotor 9. The rotor magnets 17a, 17a' form a first V-shaped magnet pair, and the rotor magnets 17b, 17b' form a second V-shaped magnet pair. Both magnet pairs are assigned to one of the magnetic rotor poles of the rotor 9. It would also be conceivable, for example, that only one rotor magnet or rotor magnet pair 17a, 17a' or 17b, 17b' is provided per magnet group F1..F3.

[0050] The radial cooling channels 16 run in the favorable configuration shown in the example.

[0051] In this embodiment, the cooling channels are located between two magnet groups F1..F3. Specifically, Fig. 4 shows the angular position b of the axis of symmetry of the first magnet group F1. One of the first cooling channels 16, arranged in the rotor lamination stack 11, runs, viewed along the rotor axis A of the rotor 9, at an angular position a, a' between two pairs of F1..F3 on V-shaped rotor magnets 17a..17b'. The two angles oc, oc' between the angular position b of the first magnet group F1 and the angular position a of the recesses E1, E3, E5 and E6, as well as the angular position a' of the recesses E2, E4 and E6', are equal in this case, so that the radial cooling channels 16, bounded by the recesses E1 ..E6', are each symmetrically located between the magnet groups F1 ..F3. This is advantageous, but not mandatory, and the cooling channels 16 can also run slightly off-center between the magnet groups F1 ..F3.

[0052] In the example shown in Fig. 4, eight magnet groups F1 ..F3 and consequently eight magnetic poles (or four pole pairs) as well as eight radially extending cooling channels 16 are provided. However, this is purely exemplary, and a different number of magnet groups F1 ..F3 and radial cooling channels 16 could also be provided. It is also conceivable that the number of radial cooling channels 16 is smaller than the number of magnet groups F1..F3. For example, cooling channels 16 could be provided only at every second possible angular position a, a'. Consequently, the rotor lamination 12a of Fig. 4 could have only four radial cooling channels 16. Furthermore, it would be conceivable that—depending on the number of pole pairs—only every third angular position a, a', every fourth angular position a, a', etc., is occupied by a cooling channel 16.

[0053] The rotor lamination 12a shown in Fig. 4 also includes an axial through-opening, or shaft bore 23, through which the rotor shaft 10 is guided. The inner diameter of the axial through-opening 23 is larger at a first edge section than at a second edge section, with the outlet opening 15 opposite the first edge section. In other words, the shaft bore 23 has radially inwardly projecting extensions 24, by means of which the rotor lamination stack 11 is pressed onto the rotor shaft 10. Indentations G are therefore located between the extensions 24, at which the press fit is free. This type of press fit is also referred to as a "partial press fit". The angular positions a, a' of the recesses E1 ..E6 and the radial cooling channels 16 are each located between the extensions 24.In this way, it is ensured that any compressive stress resulting from the press fit within the rotor sheet 12a is dissipated into more stable areas of the same (and not into the comparatively fragile area of ​​the radial cooling channels 16).

[0054] Fig. 5 additionally shows an example of a third rotor lamination 12b, which has a similar basic shape to the rotor lamination 12a of Fig. 5, but which does not have recesses E1..E5, but only the radially outermost recesses E6, E6'. The recesses E6, E6' are also identically shaped and not different like the recesses E6, E6' in rotor lamination 12a. If a third rotor lamination 12b is stacked axially on top of a first or second rotor lamination 12a, 12a', then the radial cooling channels 16 are axially limited, but the recesses E6..E6' form the axially extending cooling channels 19. The axial cooling channels 19 thus extend through the entire rotor lamination stack 11 and are formed by overlapping recesses E6..E6' in all rotor laminations 12a, 12a', 12b.

[0055] The axial cooling channels 19 can be used not only to guide the coolant but also to align the rotor laminations 12...12b' during the production of the rotor lamination stack 11. For this purpose, pins 25 are inserted into the axial cooling channels 19, one of which is shown in cross-section in Figures 4 and 5. After the production of the rotor lamination stack 11, the pin 25 is removed from the axial cooling channels 19. In this way, the axial cooling channels 19 serve a dual purpose.

[0056] In the examples shown, the radial cooling channels 16 open into axial cooling channels 19, which run between two magnet groups F1..F3, spaced apart from the rotor magnets 17..17b'. This allows the rotor magnets 17..17b' to be encased in the magnet pockets 18, for example with a plastic, and thus permanently fixed. However, this is not the only conceivable possibility. It would also be conceivable for the cooling channels 16 to open into the magnet pockets 18, with the coolant then flowing in cavities that remain in the magnet pockets 18 alongside the rotor magnets 17..17b'. It would also be conceivable for the radial cooling channels 16 to exit radially from the rotor lamination stack 11 (i.e., not opening into any axial cooling channel 19 or magnet pocket 18).

[0057] Fig. 6 now shows a detailed view of a further radial cooling channel 16, which passes through the recesses E1, E3, E5 of several first rotor laminations 12a and / or the recesses E3, E4, E6' of several second rotor laminations 12a'.

[0058] This allows the cross-section of the radial cooling channel 16 to be easily enlarged. Furthermore, this improves the width-to-height ratio of the cross-section, making the radial cooling channel 16 less shallow. In the example shown, two first rotor laminations 12a and two second rotor laminations 12a' are arranged side by side. This increases the cross-section of the radial cooling channel 16. However, it is also conceivable that a different number of first rotor laminations 12a and / or second rotor laminations 12a' could be stacked directly on top of each other to create a wider cooling channel 16.

[0059] Fig. 7 further shows a half-section through another embodiment of an electric machine 1b, which is very similar to the electric machine 1a shown in Fig. 1, except that the coolant is routed out of the rotor 9 somewhat differently. Specifically, the axial (second) cooling channel 19 opens into a third cooling channel 26a emerging from the rotor lamination stack 11. The third cooling channel 26a can exit the rotor lamination stack 11 radially or axially. In the example shown in Fig. 7, the third cooling channel 26a exits the rotor lamination stack 11 axially. Specifically, in this embodiment, the point at which the third cooling channel 26a exits the rotor lamination stack 11 is located radially further inward than the point at which the radial cooling channel 16 opens into the axial cooling channel 19.In this way, the power loss caused by the oil exiting the rotor 9 and resulting from the oil's acceleration in the tangential direction can be kept low. The division into the axial (second) cooling channel 19 and the third cooling channel 26a is not mandatory, and the section formed by the third cooling channel 26a can also be considered part of the axial (second) cooling channel 19.

[0060] Fig. 8 shows another embodiment of an electric machine 1c, which is very similar to the electric machine 1b shown in Fig. 7. However, the coolant is routed out of the rotor 9 somewhat differently. Specifically, in the end region of the rotor lamination stack 11, not as many special rotor laminations 12 are used for the third cooling channel 26b, as is the case in Fig. 7. Instead, the rotor laminations 12a, 12a', which are used to form the axial cooling channels 16, also serve to form the third cooling channel 26b. In Fig. 8, a special end plate is used, but this can also be omitted. The third cooling channel 26b then opens directly from one of the rotor laminations 12a, 12a' into the interior B of the electric machine 1c.

[0061] It is also conceivable that the rotor 9 has another rotor lamination stack 11 or lamination stack segments mounted on the rotor shaft 10, wherein both rotor lamination stacks 11 or the lamination stack segments correspond to each other and are twisted relative to each other about the axis of rotation A. In this way, inclined or stepped rotors 9 can be manufactured. This means that the magnetic poles extend over the rotor 9 in a spiral shape or their course approximates a helix.

[0062] Figure 9 shows the electric machine 1 installed in a vehicle 27. The vehicle 27 has two axles, one of which is driven. Specifically, the electric machine 1 is connected to the half-shafts 29 of the rear axle via an optional transmission 28. The driven wheels 30 are mounted on the half-shafts 29. The vehicle 27 is driven at least partially or temporarily by the electric machine 1. That is, the electric machine 1 can serve as the sole drive for the vehicle 27 or, for example, be used in conjunction with an internal combustion engine (hybrid drive). The vehicle 27 also includes an oil circuit in which the electric machine 1, the oil pump 21, and an oil cooler 31 are integrated.

[0063] In conclusion, it is noted that the scope of protection is defined by the patent claims. However, the description and drawings are to be used to interpret the claims. The features depicted in the figures can be freely exchanged and combined. In particular, it is also noted that the devices shown may, in reality, comprise more or fewer components than depicted. In some cases, the devices shown, or their components, may also be depicted not to scale and / or enlarged and / or reduced in size.

[0064] Reference symbol list

[0065] 1a..1 c electric machine

[0066] 2 Stator housings

[0067] 3 first warehouse sign

[0068] 4 second warehouse sign

[0069] 5 machine housings

[0070] 6 Stator

[0071] 7 Stator lamination stack

[0072] 8 Stator winding head

[0073] 9 Rotor

[0074] 10 Rotor shaft

[0075] 11 Rotor lamination package

[0076] 12..12b Rotor plate

[0077] 13a, 13b (rolling) bearings

[0078] 14 Central bore / internal cavity

[0079] 15 radial outlet openings / radial coolant bores

[0080] 16 radial (first) cooling channel

[0081] 17..17b' Rotor magnet

[0082] 18 magnetic pockets

[0083] 19 axial (second) cooling channel

[0084] 20 coolant nozzles

[0085] 21 Pump

[0086] 22 Bridge

[0087] 23 axial through-hole / shaft bore

[0088] 24 second marginal section / extension (section-by-section press fit)

[0089] 25 Pin 26a, 26b third cooling channel

[0090] 27 vehicles

[0091] 28 gearboxes

[0092] 29 Half axle 30 Wheel

[0093] 31 Cooler cx, cx' Rotation angle a, a' Angle position Cooling channel b Angle position Magnetic pocket

[0094] A Rotor axis / Stator axis

[0095] B Interior of the electric machine

[0096] C Coolant flow D1 , D2 Changeover cooling channel

[0097] E1..E6" recess

[0098] F1 ..F3 magnet group / rotor magnet pair

[0099] G first edge section / indentation

Claims

Patent claims 1. Rotor (9) for an electric machine (1a..1c), comprising a rotor shaft (10) with an axial central bore (14) and a radial outlet opening (15) connected to the central bore (14), a rotor lamination stack (11) mounted on the rotor shaft (10) with several axially stacked rotor laminations (12, 12a, 12a', 12b) and several rotor magnets (17..17b') arranged in the rotor lamination stack (11) in several magnet groups (F1 ..F3), each assigned to a different rotor pole of the rotor (9), characterized in that a radial cooling channel (16), the inlet opening of which is opposite the outlet opening (15), is provided in the rotor lamination stack (11) by several recesses (E1 , E3, E5) in a first rotor lamination (12a, 12a') and at least one recess (E2, E4, E6') runs in a second rotor plate (12a, 12a') adjacent to the first rotor plate (12a, 12a').

2. Rotor (9) according to claim 1 , characterized in that the radial cooling channel (16) runs between two magnet groups (F1..F3).

3. Rotor (9) according to claim 1 or 2, characterized in that the at least one recess (E2, E4, E6') in the second rotor sheet (12a, 12a') is offset from the recesses (E1 , E3, E5) in the first rotor sheet (12a, 12a') and the recesses (E1..E6“) in the first rotor sheet (12a, 12a') and second rotor sheet (12a, 12a') overlap each other.

4. Rotor (9) according to one of the preceding claims, characterized in that the radial cooling channel (16) runs through the recesses (E1 , E3, E5) of several first rotor laminations (12a, 12a') and / or the recesses (E2, E4, E6') of several second rotor laminations (12a, 12a').

5. Rotor (9) according to one of the preceding claims, characterized in that the first rotor laminations (12a, 12a') and the second rotor laminations (12a, 12a') are identical, wherein the first rotor laminations (12a, 12a') are rotated relative to the second rotor laminations (12a, 12a') about the axis of rotation (A) of the rotor (9).

6. Rotor (9) according to one of the preceding claims, characterized in that the radial cooling channel (16) is axially limited by two third rotor laminations (12b).

7. Rotor (9) according to one of the preceding claims, characterized in that the radial cooling channel (16) exits radially from the rotor lamination stack (11) or opens into an axial cooling channel (19) formed by the rotor laminations (12, 12a, 12a', 12b).

8. Rotor (9) according to claim 7, characterized in that the axial cooling channel (19) runs between two magnet groups (F1..F3) spaced apart from the rotor magnets (17..17b').

9. Rotor (9) according to one of the preceding claims, characterized in that the rotor shaft (10) is guided through an axial through-opening (23) of the rotor lamination stack (1 1 ), the inner diameter of which is larger at a first edge section (G) than at a second edge section (24), wherein the outlet opening (15) is opposite the first edge section.

10. Rotor (9) according to one of the preceding claims, characterized in that the rotor (9) has a further rotor lamination stack (1 1 ) mounted on the rotor shaft (10), wherein both rotor lamination stacks (1 1 ) correspond to each other and are rotated relative to each other about the axis of rotation (A).

11. Electric machine (1 a..1 c), comprising a stator (6) and a rotor (9) rotatably mounted therein according to one of claims 1 to 10.

12. Vehicle (27) with an electric machine (1 a..1 c) according to claim 11, which is provided for driving the vehicle (27).

13. Method for operating an electric machine (1a..1 c) according to claim 11 , characterized in that a coolant is directed from the central bore (14) through the radial outlet opening (15) into the radial cooling channel (16).

14. Method for manufacturing a rotor (9) according to claim 7, characterized in that the rotor lamination stack (11 ) is aligned with a pin (25) inserted into the axial cooling channel (19).

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