Rotor for an electric traction machine, traction machine and motor vehicle

Abstract

The invention relates to a rotor (16) for an electric traction machine (10), comprising a rotor shaft (18), a laminated core (20) fixed to rotation on the rotor shaft (18) and wound by a rotor winding (22), and a distributor element (24) arranged at the end face of the laminated core (20), which is configured to direct a cooling fluid (28) flowing out of the rotor shaft (18) to the rotor winding (22), whereby the cooling fluid (28) flows directly over the rotor winding (22) and cools the rotor winding (22) during operation.

Description

[0001] The invention relates to a rotor for an electric traction machine, a traction machine for a motor vehicle and a motor vehicle with a traction machine.

[0002] DE 10 2014 018 223 A1 discloses an electric machine with a rotor configured as a squirrel-cage rotor, which has at least one short-circuit ring and a rotor core with at least one cooling channel. The cooling channel extends from a first axial end of the rotor core to an opposite second axial end of the rotor core and can be supplied with a coolant via a coolant inlet channel. The coolant inlet channel extends radially in the short-circuit ring from an inner radius of the short-circuit ring to the cooling channel.

[0003] Furthermore, WO 2023 / 001954 A1 discloses a rotor for a separately excited electric machine of a motor vehicle. The rotor has a yoke with a plurality of pole teeth, with a rotor winding arranged on each pole shaft of respective pole teeth. A slot wedge is arranged in a slot between the rotor winding of two adjacent pole teeth. On the outer side of the slot wedge facing the respective rotor winding, a layer of an elastomer is arranged, against which the rotor winding rests at least partially and / or in sections. By clamping the slot wedge to the rotor winding, potting the rotor winding with a potting material is eliminated. The rotor winding is thus arranged on the pole shaft without potting.

[0004] The object of the present invention is to provide a solution by means of which a rotor of a particularly powerful electric traction machine can be cooled particularly efficiently.

[0005] This object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0006] The invention relates to a rotor for an electric traction machine, in particular an electric traction machine of a motor vehicle. The electric traction machine can be part of an electric drive train of the motor vehicle and be designed to drive the motor vehicle electrically using electrical energy from a vehicle battery of the motor vehicle. In addition to the rotor, the electric traction machine comprises a stator, relative to which the rotor rotates about a rotational axis during operation. The traction machine is in particular a synchronous machine in which a constantly magnetized rotor is synchronously driven by a moving magnetic rotating field in the stator. The field in the rotor and thus in the rotor is generated by external electromagnetic excitation with a field coil, in particular a rotor winding, on the rotor and a power supply via slip rings.The rotor comprises a rotor shaft and a laminated core mounted on the rotor shaft for rotation therewith. The rotor winding is wound around this laminated core. The rotor can be separately excited via this rotor winding. The rotor further comprises a distributor element arranged on the end face of the laminated core, which is designed to guide a coolant flowing from the rotor shaft to the rotor winding. As a result, the coolant flows directly onto the rotor winding and cools the rotor winding during operation. This means that the distributor element is designed to guide the coolant directly to the rotor winding, causing the coolant to flow over the rotor winding. There is therefore direct contact between the coolant and the rotor winding. The coolant can be oil, for example.Due to the direct contact between the rotor winding and the cooling fluid, a large amount of heat can be removed from the rotor winding particularly quickly by the cooling fluid, allowing the rotor winding to be cooled particularly efficiently. As a result, the traction machine containing the rotor can deliver particularly high power.

[0007] In a possible further development of the invention, the rotor is free of any potting compound. This means that the rotor winding is not potted. This allows the rotor to be manufactured particularly cost-effectively and with a low weight. Due to the particularly efficient direct cooling of the rotor winding as a result of the direct contact with the coolant, the traction machine comprising the rotor can be operated with particularly high continuous power and at a particularly high speed level.

[0008] In a further possible embodiment of the invention, the distributor element has a plurality of openings through which the cooling liquid can flow out of the distributor element, each of the openings being directly aligned with the point on the rotor that is to be cooled by means of the cooling liquid. In particular, the respective openings are aligned with areas of greatest heat development in the rotor winding, as a result of which these areas of greatest heat development in the rotor winding can be cooled particularly well and efficiently by means of the cooling liquid. In particular, due to the alignment of the openings, the cooling liquid first hits these areas of greatest heat development in the rotor winding, as a result of which the cooling liquid still has a particularly low temperature when it hits these areas of the rotor winding.As a result, these areas of the rotor where the greatest heat generation occurs can be cooled particularly efficiently and powerfully by the coolant. As a result, the traction motor can deliver particularly high continuous power. Furthermore, the cooling fluid can be easily guided to the rotor winding via the openings in the distributor element. Furthermore, the openings can be easily incorporated into the distributor element during its manufacture.

[0009] In this context, it is particularly provided that a nozzle is provided for at least one of the openings, by means of which a flow characteristic of the cooling liquid flowing out of the distributor element via this opening can be adjusted. As a flow characteristic, for example, a degree of turbulence and / or a flow direction and / or a flow angle and / or a shape of a spray cone of the cooling liquid exiting the distributor element via this opening can be adjusted. By adjusting the flow characteristic of the cooling liquid flowing out of the distributor element via the respective opening, a heat transfer from the rotor winding to the cooling liquid flowing along the rotor winding can be adjusted.In this case, the flow characteristics of the cooling liquid are adjusted by means of the nozzle in particular in such a way that heat transfer from the rotor winding to the cooling liquid is particularly high, whereby the rotor winding can be cooled particularly strongly by means of the cooling liquid flowing along the rotor winding.

[0010] In a further possible embodiment of the invention, it is provided that at least one rotor slot opening is aligned with a rotor slot, whereby coolant flowing out of this rotor slot opening flows into this rotor slot. Alternatively or additionally, it can be provided that at least one rotor winding head opening is aligned with a winding region of the rotor winding assigned to the rotor winding head, whereby coolant flowing out of this rotor winding head opening flows onto this winding region. In other words, by means of the distributor element, the coolant can be directed directly into respective rotor slots of the rotor and / or directly onto a winding region of the rotor winding assigned to the rotor winding head. As a result, the rotor winding can be cooled particularly well in the rotor slot region or in the winding region assigned to the rotor winding head.Both the rotor winding head and the respective areas of the rotor winding adjacent to the rotor slots are areas of the rotor winding where particularly high heat generation occurs during operation. Targeted cooling of these areas can minimize the risk of rotor overheating. As a result, the electric traction machine can operate at a particularly high continuous power.

[0011] In a further possible embodiment of the invention, the distributor element has a rotor slot opening for each rotor slot. This means that each rotor slot of the rotor is assigned a rotor slot opening, whereby cooling fluid can be reliably guided into each of the rotor slots of the rotor via the respective rotor slot opening. This ensures that the rotor winding is reliably and, in particular, sufficiently cooled in all areas assigned to the respective rotor slots of the rotor, thereby enabling a particularly high continuous power output of the electric traction machine having the rotor to be achieved.

[0012] In a further possible embodiment of the invention, the distributor element has at least one stator opening as an opening, which, when used as intended, is aligned with a stator of the traction machine. As a result, the stator opening is designed to direct coolant onto the stator during operation. In other words, the distributor element has at least one stator opening through which the coolant flowing out of the distributor element can be guided to the stator, avoiding direct initial contact with the rotor winding. As a result, a stator winding of the stator can be directly cooled by means of the coolant flowing out of the distributor element via this stator opening. As a result, the risk of stator overheating can be kept particularly low.In particular, during operation, the cooling liquid flowing out of the distributor element via the at least one stator opening flows past the rotor to the stator without direct contact with the rotor winding of the rotor, and in particular without direct contact with the rotor. This ensures that the cooling liquid has a particularly low temperature upon contact with the stator, since heat absorption from the rotor before impacting the stator is at least substantially eliminated. This allows the stator to be cooled particularly efficiently by means of the cooling liquid. In particular, the cooling liquid impacts directly on the stator winding of the stator, whereby the stator winding can be cooled particularly well by the cooling liquid flowing directly along it.Due to the particularly efficient cooling of the stator by means of the cooling liquid flowing out of the distributor element via at least one stator opening, the traction machine can be operated with a particularly high continuous power.

[0013] In a further possible embodiment of the invention, the distributor element comprises a reservoir in which the cooling fluid flowing into the distributor element can be collected before the cooling fluid is distributed to the rotor winding. Collecting the cooling fluid in the reservoir ensures that the cooling fluid, which flows out of the distributor element, for example, through several openings, has at least substantially the same temperature. This allows for particularly uniform cooling of the rotor or stator by means of the cooling fluid.

[0014] The invention further relates to a traction machine for a motor vehicle, comprising a stator and a rotor rotatable relative to the stator about a rotational axis, as already described in connection with the rotor according to the invention. The traction machine is, in particular, a current-excited synchronous machine. The rotor's distributor element allows the rotor winding and, optionally, the stator winding to be cooled particularly efficiently, enabling the traction machine to deliver particularly high power.

[0015] The invention further relates to a motor vehicle with a traction machine as already described in connection with the traction machine according to the invention. The traction machine is part of an electric drive train of the motor vehicle. The motor vehicle can thus be driven electrically by means of the traction machine. The motor vehicle is, in particular, a motor vehicle, in particular a passenger car.

[0016] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0017] The drawing shows: Fig. 1 is a schematic perspective view of a rotor of an electric traction machine, looking toward a rear side of the rotor; Fig. 2 is a schematic perspective view of a distributor element of the rotor; and Fig. 3 a schematic perspective view of the electric traction machine with a stator and the rotor looking at a front side of the rotor.

[0018] In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0019] In Fig. 3 shows an electric traction machine 10 for an electrically driven motor vehicle. The electric traction machine 10 comprises a stator 12 and a rotor 16 that is rotatable relative to the stator 12 about a rotational axis 14. This rotor 16 is separately Fig. 1. As shown in the Fig. 1 and Fig. 3, the rotor 16 is designed without casting. The rotor 16 comprises a rotor shaft 18, on which a laminated core 20 is held in a rotationally fixed manner. A rotor winding 22 is wound onto this laminated core 20. A distributor element 24 of the rotor 16 is arranged on the end face of the laminated core 20. This distributor element 24 is in Fig. 2 is shown separately in a perspective view. Fig. 2 the distributor element 24 is shown in a plan view of a contact side, which, when the distributor element 24 is arranged on the end face of the laminated core 20, is oriented towards the rotor winding 22.

[0020] The distributor element 24 is injection-molded from a plastic. In this case, the rotor 16 comprises two distributor elements 24, one of which is Fig. 1 shown back and one on the in Fig. 3. The distributor element 24 is star-shaped in the present case and is seated in a rotationally fixed manner on the rotor shaft 18. The distributor element 24 can be applied to respective rotor winding ends 26 of the rotor winding 22 arranged on the front side of the rotor 16. The distributor element 24 is designed to guide a cooling liquid 28, in this case oil, to the rotor winding 22. In the figures, spray jets of the cooling liquid 28 flowing out of the distributor element 24 are shown conically. For reasons of clarity, only individual spray cones of the cooling liquid 28 are provided with the corresponding reference numerals.

[0021] The distributor element 24 has, as in Fig. 2, has a closed ring shape, wherein the distributor element 24 is aligned with its central axis concentrically to the axis of rotation 14 of the rotor 16 by being plugged onto the rotor shaft 18. The distributor element 24 has a plurality of inlet openings 32 on the inner wall 30 aligned with the central axis. When the distributor element 24 is plugged onto the rotor shaft 18, the inner wall 30 rests against the rotor shaft 18 on the outer circumference. The inlet openings 32 are brought into alignment with respective outlet openings of the rotor shaft 18, whereby coolant 28 flowing out of the rotor shaft 18 via the outlet openings can flow into the distributor element 24 via the respective inlet openings 32 of the distributor element 24 assigned to the outlet openings. The coolant 28 flowing into the distributor element 24 via the inlet openings 32 can be collected in a reservoir enclosed by the distributor element 24.The cooling fluid 28 can then flow out of the distributor element 24 through at least one opening 34. For reasons of clarity, only some of the openings 34 are provided with the corresponding reference numerals.

[0022] The distributor element 24 in this case has a plurality of rotor slot openings 36, which, when the distributor element 24 is properly installed in the rotor 16, are aligned with the respective associated rotor slots 38 of the rotor 16. As a result, cooling fluid 28 flowing out of the respective rotor slot opening 36 during operation flows directly into the associated rotor slot 38. The distributor element 24 in this case further comprises a plurality of rotor winding head openings 40. The respective rotor winding head openings 40 are each aligned with a winding region of the rotor winding 22 associated with the rotor winding head 26. As a result, cooling fluid 28 flowing out of the respective rotor winding head opening 40 flows directly onto this winding region of the rotor winding 22.

[0023] In the present case, the distribution element 24 has an associated rotor slot opening 36 for each rotor slot 38. Furthermore, it is provided that the distribution element 24 has an associated rotor winding head opening 40 for each pole shaft of the laminated core 20 around which a wire of the rotor winding 22 is deflected. This allows for particularly uniform cooling of the rotor winding head 26 by means of the cooling fluid 28.

[0024] As in the Fig. 2 and Fig. 3, the distributor element 24 has at least one stator opening 42. Cooling fluid 28 exiting the distributor element 24 via this stator opening 42 flows to a stator winding head 44 of the stator 12, whereby this stator winding head 44 is cooled by means of the cooling fluid 28.

[0025] As in Fig. 2, the distributor element 24 in this case comprises a plurality of spacer elements 46, which are particularly designed to be brought into contact with the rotor winding 22 or with the laminated core 20. The spacer elements 46 are designed to maintain a predetermined distance between the laminated core 20 or the rotor winding 22 and the distributor element 24.

[0026] Furthermore, the distributor element 24 comprises, as in Fig.2, a plurality of recesses 48. Respective winding regions of the rotor winding 22 assigned to the rotor winding head 26 can be inserted into these recesses 48 when the distributor element 24 is arranged on the end face of the laminated core 20. As a result, the distributor element 24 can be arranged particularly close to the laminated core 20 in the axial direction, whereby a free path over which the cooling fluid 28 flows from the distributor element 24 to the rotor winding 22 without direct guidance can be kept particularly short.

[0027] The distributor element 24 is configured to guide the coolant 28 to hot spots on the rotor 16 and, if appropriate, also on the stator 12. A diameter, an arrangement of the respective openings 34, an opening angle of the respective opening 34, and an inclination of a bore of the distributor element 24 leading into the respective opening 34 are selected depending on the respective cooling requirement and the respective position of the spot on the electric traction machine 10 to be cooled by means of the coolant 28 flowing out of this opening 34.

[0028] To enable a particularly targeted discharge of the cooling liquid 28 from the distributor element 24, a horn extension can be provided as a nozzle for at least one of the openings 34. The nozzle can be used to adjust the flow characteristics of the cooling liquid 28 flowing out of the distributor element 24 through this opening 34 with particular precision.

[0029] Due to the potting-free design of the rotor 16, the rotor 16 and the traction machine 10 comprising the rotor 16 are particularly lightweight. In addition, the direct flow of the cooling fluid 28 via the rotor winding 22 enables particularly efficient cooling of the rotor 16. This allows for particularly high peak power, a particularly high available torque, and a particularly high continuous power of the electric traction machine 10. Furthermore, the potting-free design allows the rotor 16 to be manufactured particularly cost-effectively. By means of the distributor element 24, the cooling fluid 28 can be directed directly to the hottest points of the traction machine 10, in particular the rotor 16. This enables targeted cooling of the hotspots of the electric traction machine 10. As a result, the rotor 16 is particularly well suited for the high-performance sector.By means of the described distribution element 24, which can also be referred to as an oil distributor, it is possible to provide a cost-effective and lightweight rotor for a particularly high continuous power and a particularly high speed level of the traction machine 10. Speed ​​stability can be achieved by a locking cover slide, and a cost and weight reduction can be achieved by eliminating the casting compound and other components, such as sleeve supports or heat sinks. A particularly high performance of the traction machine 10, in particular a particularly high continuous power, can be achieved by the described distribution element 24, which is configured to distribute the oil as cooling fluid 28 into the rotor slots 38, onto the respective rotor winding overhangs 26 of the rotor 16, and onto the stator winding overhang 44 of the stator 12.

[0030] Overall, the invention shows how the cast-free rotor 16 can be created, with oil cooling for the rotor 16 and the stator 12 by means of the oil distributor, ie the distributor element 24. List of reference symbols 10 electric traction machine 12 Stator 14 axis of rotation 16 Rotor 18 Rotor shaft 20 sheet packages 22 Rotor winding 24 distribution element 26 Rotor winding head 28 Coolant 30 interior wall 32 Entrance opening 34 Opening 36 Rotor slot opening 38 Rotor groove 40 Rotor winding head groove 42 Stator opening 44 Stator winding head 46 spacers 48 recess QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 018 223 A1

[0002] WO 2023 / 001954 A1

[0003]

Claims

[1] Rotor (16) for an electric traction machine (10), with a rotor shaft (18), with a laminated core (20) which is seated on the rotor shaft (18) in a rotationally fixed manner and around which a rotor winding (22) is wound, and with a distributor element (24) which is arranged on the end face of the laminated core (20) and which is designed to guide a cooling liquid (28) flowing out of the rotor shaft (18) to the rotor winding (22), as a result of which the cooling liquid (28) flows directly over the rotor winding (22) and in the process cools the rotor winding (22) during operation. [2] Rotor (16) according to claim 1, characterized by that the rotor (16) is free of potting compound. [3] Rotor (16) according to claim 1 or 2, characterized bythat the distributor element (24) has a plurality of openings (34) through which the cooling liquid (28) can flow out of the distributor element (24), wherein each of the openings (34) is directly aligned with the point on the rotor (16) which is to be cooled by means of the cooling liquid (28). [4] Rotor (16) according to claim 3, characterized by that a nozzle is provided for at least one of the openings (34), by means of which a flow characteristic of the cooling liquid (28) flowing out of the distributor element (24) via this opening (34) can be adjusted. [5] Rotor (16) according to claim 3 or 4, characterized bythat as an opening (34) at least one rotor slot opening (36) is aligned with a rotor slot (38), whereby cooling liquid (28) flowing out of this rotor slot opening (36) flows into this rotor slot (38), and / or as an opening (34) at least one rotor winding head opening (40) is aligned with a winding region of the rotor winding (22) assigned to the rotor winding head (26), whereby cooling liquid (28) flowing out of this rotor winding head opening (40) flows onto this winding region. [6] Rotor (16) according to claim 5, characterized by that the distributor element (24) has a rotor groove opening (36) for each rotor groove (38). [7] Rotor (16) according to one of claims 3 to 6, characterized bythat the distributor element (24) has as opening (34) at least one stator opening (42) which, when used as intended, is aligned with a stator (12) of the traction machine (10), whereby the stator opening (42) is designed to direct cooling liquid (28) onto the stator (12) during operation. [8] Rotor (16) according to one of the preceding claims, characterized by that the distributor element (24) has a reservoir in which the cooling liquid (28) flowing into the distributor element (24) can be collected before the cooling liquid (28) is distributed to the rotor winding (22). [9] Traction machine (10) for a motor vehicle, comprising a stator (12) and a rotor (16) rotatable relative to the stator (12) about an axis of rotation (14) according to one of the preceding claims. [10] Motor vehicle with a traction machine (10) according to claim 9.

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