Electric drive for a vehicle and oil jet ring for an electric drive

Abstract

Electric drive (1) for a vehicle (100), the electric drive (1) comprising: – an electric machine (3) having a stator (4), the stator (4) comprising a stator core (5) with an axial face side (6) and a stator winding (9) forming a winding head (10) at the face side (6); – AC busbars (12) being arranged with an axial distance to the face side (6) and being connected to the stator winding (9) for supplying an AC voltage to the stator winding (9); and – an oil jet ring (19) being attached to the face side (6) at a radial position more outwards than the winding head (10), the oil jet ring (19) comprising first type nozzles (20) being configured to jet a coolant towards the winding head (10); wherein the oil jet ring (19) further comprises second type nozzles (21) configured to jet the coolant towards the AC busbars (12).

Description

[0001] Electric drive for a vehicle and oil jet ring for an electric drive

[0002] The present invention relates to an electric drive for a vehicle. Aside, the invention relates to an oil jet ring for an electric drive.

[0003] In electric drives with an electric machine, oil jet rings are commonly used to cool a winding head of a stator of the electric machine. Thereto, the oil jet ring is provided with nozzles directed towards the winding head so as to jet a coolant from upon the winding head.

[0004] Exemplarily, DE 10 2022 205443 A1 discloses a ring for an electric machine in a vehicle. The ring has nozzles and is configured to jet a coolant through the nozzles upon stator windings of the electric machine.

[0005] It as object of the present invention to improve the cooling performance of an electric drive for a vehicle.

[0006] According to the invention, this object is solved by an electric drive for a vehicle, the electric drive comprising: an electric machine having a stator, the stator comprising a stator core with an axial face side and a stator winding forming a winding head at the face side; AC busbars being arranged with an axial distance to the face side and being connected to the stator winding for supplying an AC voltage to the stator winding; and an oil jet ring being attached to the face side at a radial position more outwards than the winding head, the oil jet ring comprising first type nozzles being configured to jet a coolant towards the winding head; wherein the oil jet ring further comprises second type nozzles configured to jet the coolant towards the AC busbars.

[0007] The electric drive according to the invention comprises an electric machine. The electric machine has a stator. The stator comprises a stator core with an axial face side. The stator further comprises a stator winding. The stator winding forms a winding head at the face side.

[0008] The electric drive according to the invention further comprises AC busbars. The AC busbars are arranged with an axial distance to the face side. The AC busbars are connected to the stator winding for supplying an AC voltage to the stator winding.

[0009] The electric drive according to the invention further comprises an oil jet ring. The oil jet ring is attached to the face side at a radial position more outwards than the winding head. The oil jet ring comprises first type nozzles. The first type nozzles are configured to jet a coolant towards the winding head. The oil jet ring further comprises second type nozzles. The second type nozzles are configured to jet the coolant towards the AC busbars.

[0010] The AC busbars of the electric drive have been identified to be a relevant heat source, which can be actively cooled by a coolant as well. For this purpose, the cooling ability of the oil jet ring is enhanced by providing the second type nozzles, which are configured to jet the coolant towards the AC busbar. Accordingly, a costly separate cooling means for the AC busbar can be omitted and an integral cooling solution is provided, which actively dissipates heat from the winding head as well as from the AC busbars.

[0011] The electric machine may be a synchronous motor or an induction motor. Preferably, the electric machine further comprises a rotor mounted rotatable with regard to the stator. The stator winding may be a hairpin winding. The stator core may comprise a plurality of stacked metal sheets, which are electrically insulated against each other in the axial direction.

[0012] The electric drive may further comprise an inverter configured to convert a DC voltage into the AC voltage. The inverter may be connected to the stator windings via the AC busbars. The terms “axial”, “radial” and “circumferential” refer to a longitudinal axis of the stator core, which corresponds to a rotation axis of the electric machine.

[0013] With regard to the electric drive according to the invention, it is preferred that the second type nozzles are configured to jet the coolant away from the oil jet ring into a direction having a larger axial component than a direction into which the first type nozzles jet the coolant away from the oil jet ring. Therein, the axial component is defined to be positive, when pointing away from the face side.

[0014] Therein, the second type nozzles may extend along the axial direction. The first type nozzles may extend along the radial direction or may extend along the radial direction with an axial inclination.

[0015] Further, the oil jet ring may form an attachment side being attached to the face side, an inner side facing the winding head and an outer side being opposite to the inner side. Therein, the first type nozzles may extend from the outer side to the inner side.

[0016] According to a preferred design, the oil jet ring forms a fourth side opposite to the attachment side, the second type nozzles being arranged at the fourth side. The fourth side may be perpendicular to the longitudinal axial of the stator core.

[0017] The electric drive may further comprise a housing forming a machine accommodation space, inside which the electric machine is arranged. The outer side of the oil jet ring and the housing may limit an annular fluid chamber which supplies the coolant to the first type nozzles and / or to the second type nozzles.

[0018] Further, the machine accommodation space and the stator core may limit a cooling jacket for guiding the coolant circumferentially around the stator core. The cooling jacket may be configured to supply the coolant into the fluid chamber. In the electric drive according to the invention, the number of first type nozzles may be higher than the number of second type nozzles. Alternatively or additionally, the second type nozzles may be provided within a sector of at most 120 degrees, preferably at most 90 degrees, more preferably at most 60 degrees of the oil jet ring. Outside the sector, no second type nozzles or only first type nozzles may be provided. Typically, the first type nozzles are distributed about the longitudinal axis.

[0019] Preferably, each second type nozzle is formed by an opening of the oil jet ring. More preferably, a plug may be inserted into the opening. The plug may comprise a shaft and a trough-hole extending through the shaft. The diameter and the shape of the through-hole allows to specify the amount of coolant jetted through the nozzle. Of course, it is also possible to form the second type nozzles without a plug in the opening.

[0020] Therein, at the side, where the coolant leaks the second type nozzle, the plug may extend out of the oil jet ring. This allows to direct the coolant to the position, where the AC busbars are situated, even in cases, where the AC busbars have a significantly larger distance to the oil jet ring than the distance between the winding head and the first type nozzles.

[0021] The through-hole may be straight or tapered or choked. This allows do define a desired geometry of the jet directed towards the AC busbars.

[0022] The plug may comprise a head, through which the through-hole extends, the head being arranged at a side of the oil jet ring opposite to the side where the coolant leaks the second type nozzle. By providing the head, the plug can be robustly fastened in the opening.

[0023] Further, the oil jet ring comprises one or multiple further openings corresponding to the openings, each further opening being closed by a blind plug. By providing the blind plug, openings that are not necessary to cool the AC busbar of the electric drive can be closed so as to avoid coolant to be jetted without cooling effect to the AC busbars. Nonetheless, the oil jet ring with the further openings can also be used in other electric drives, where a larger amount of second type nozzles is desired. Thus, a single oil jet ring can be adapted in several designs of electric drives, choosing whether and how many blind plugs are provided.

[0024] The above object is further solved by an oil jet ring for an electric drive, in particular for an electric drive as described above, wherein the oil jet ring forms an attachment side, an inner side, an outer side being opposite to the inner side, first type nozzles extending from the outer side to the inner side and configured to jet a coolant away from the inner side and second type nozzles configured to jet the coolant away from the oil jet ring into a direction having a larger axial component than a direction into which the first type nozzles jet the coolant away from the oil jet ring.

[0025] All statements regarding the oil jet ring of the electric drive according to the invention apply analogously to the oil jet ring according to the invention. Therein, the longitudinal axis of the stator corresponds to a longitudinal axis of the oil jet ring.

[0026] The above object is further solved by a vehicle, comprising an electric drive according to the invention or an electric drive with an oil jet ring according to the invention, the electric drive being configured to propel the vehicle.

[0027] Further details and advantages of the invention are disclosed in the following. Therein, reference is made to the schematic drawings, which show:

[0028] Fig. 1 a principle cross-sectional view of a first embodiment of an electric drive according to the invention with an embodiment of an oil jet ring according to the invention;

[0029] Fig. 2 a principle front view of the oil jet ring according to the first embodiment; Fig. 3 a principle cross-sectional view of the oil jet according to the first embodiment through first and second type nozzles;

[0030] Fig. 4 a principle cross-sectional view of an oil jet ring through a second type nozzle according to a second embodiment;

[0031] Fig. 5 a principle cross-sectional view of an oil jet ring through a second type nozzle according to a third embodiment; and

[0032] Fig. 6 a principle cross-sectional view of an oil jet ring through a second type nozzle according to a fourth embodiment; and

[0033] Fig. 7 a principle drawing of an embodiment of a vehicle according to the invention.

[0034] Fig. 1 is a principle cross-sectional view of a first embodiment of an electric drive 1 with a first embodiment of an oil jet ring 19.

[0035] The electric drive 1 comprises an electric machine 3 having a stator 4. The stator 4 comprises a stator core 5, which has an axial first face side 6, an opposing axial second face side 7 and a longitudinal axis 8. The stator 4 further comprises a stator winding 9, which forms a first winding head 10 at the first face side 6 and a second winding head 1 1 at the second face side 7.

[0036] In particular detail, the stator core 5 many be made of a plurality of axially stacked metal sheets, which are electrically isolated against each other. Exemplarily, the stator winding 9 is a hairpin winding.

[0037] Further, the electric drive comprises AC busbars 12, which are arranged with an axial distance to the first face side 6 and connected to the stator winding 9 for supplying an AC voltage to the stator winding 9. Exemplarily, the stator winding 9 has three phases and a corresponding number of AC busbars 12 is provided. In more detail, the AC busbars 12 are connected to an inverter 13 of the electric drive 1 , which is configured to convert a DC voltage into the AC voltage for supplying the stator winding 9.

[0038] In further detail, Fig. 1 shows a rotor 14 being arranged rotatably withing the stator 4 or stator core 5, respectively, and a shaft 15 being attached to the rotor 14 in a torque-proof manner. Therein a rotation axis of the shaft 15 corresponds to the longitudinal axis 8. Also, a housing 16 of the electric drive 1 is depicted in Fig. 1 . The housing 16 forms a machine accommodation space 17, inside which the electric machine 3 is arranged, and an inverter accommodation space 18, inside which the inverter 13 is arranged. The housing 1 may be an integral housing, which forms the separated accommodation spaces 17, 18 and comprises an interface for leading the busbars 12 from the inverter accommodation space 18 into the machine accommodation space 17.

[0039] The electric drive 1 further comprises an oil jet ring 19, which is attached to the first face side 6 at a radial position more outwards than the first winding head 10. The oil jet ring 19 comprises first type nozzles 20, which are configured to jet a coolant towards the first winding head 10, and second type nozzles 21 , which are configured to jet the coolant towards the AC busbars 12. The second type nozzles 21 allow to cool the busbars 12 with the same coolant as used for cooling the first winding head 10 by means of the first type nozzles 20.

[0040] Therein, the second type nozzles 21 are configured to jet the coolant away from the oil jet ring 19 into a direction having a larger axial component than a direction into which the first type nozzles 20 jet the coolant away from the oil jet ring 19.

[0041] As can be seen in Fig. 1 , the oil jet ring 19 forms an attachment side 22 being attached to the first face side 6. Further, the oil jet ring 19 forms an inner side 23 facing the first winding head 10 and an outer side 24 being opposite to the inner side 23. A fourth side 25 of the oil jet ring 19 is formed opposite to the attachment side 22. Therein, the first type nozzles 20 extend from the outer side 24 to the inner side 23 and the second type nozzles 21 are arranged at the fourth side 25.

[0042] For supplying the coolant, the outer side 24 of the oil jet ring 19 and the housing 16 limit an annular fluid chamber 26, which supplies the coolant to the first type nozzles 20 and the second type nozzles 21 . The fluid chamber 26 is connected in a fluid-conductive manner to a cooling jacket 27 limited by the machine accommodation space 17 and the stator core 5. The cooling jacket 27 guides the coolant circumferentially around the stator core 5 for cooling the stator 4 and supplies the coolant into the fluid chamber 26.

[0043] Fig. 2 is a principle front view of the first oil jet ring 19 according to the first embodiment as seen from the first face side 6.

[0044] The first type nozzles 20 are distributed circumferentially about the longitudinal axis 8, whereas the second type nozzles 21 are provided only in a sector of the oil jet ring 19, where the AC busbars 12 extend along the oil jet ring 19.

[0045] Each second type nozzle 21 is formed by an opening 28 of the oil jet ring 19. The oil jet ring 19 is further provided with multiple further openings 29, which correspond to the opening 28. Therein, the further openings 29 are closed by a blind plug 30. By closing the further openings 29, the area, where the coolant leaks the second type nozzles 21 , is restricted to the sector, where the AC busbars 12 are arranged. Nonetheless, the oil jet ring 19 can be adapted to other electric drives, where the corresponding AC busbars extend over a larger sector of the oil jet ring 19, by simply removing the blind plugs 30.

[0046] Fig. 3 is a principle cross-sectional view of the oil jet ring 19 according to the first embodiment through first and second type nozzle 20, 21 . In the present embodiment the first type nozzles 20 extend in an inclined manner into the radial direction, whereas the second type nozzles 21 extend into the axial direction.

[0047] Again with reference to Fig. 1 , the electric drive 1 can be provided with a further oil jet ring 19’ attached to the second face side 7 of the stator core 5. The second oil jet ring 19’ comprises first type nozzles 20’ but lacks second type nozzles 21 as there are no AC busbars 12 at the second face side 7.

[0048] In the following, further embodiments of an electric drive 1 are described. Therein, all statements concerning the first embodiment apply to the further embodiments as well. Identical or equivalent components are denoted by the same reference numerals.

[0049] Fig. 4 is a principle cross-sectional view of the oil jet ring 19 through a second type nozzle 21 according to a second embodiment.

[0050] The second type nozzles 21 is formed by the opening 28 and a plug 31 inserted into the opening 28. The plug 31 comprises a shaft 32, a trough-hole 33 extending through the shaft 32 and a head 34 through which the through-hole 33 extends. The head 34 is arranged at a side of the oil jet ring 19 opposite to the side where the coolant leaks the second type nozzle 21 . At the side, where the coolant leaks the second type nozzle 21 , the plug 31 extends out of the oil jet ring 19. Thereby, the distance between the second type nozzle 21 and the AC busbars 12 can be decreased. According to the second embodiment, the through-hole 33 is straight.

[0051] Fig. 5 is a cross-sectional view of the oil jet ring 19 through a second type nozzle 21 according to a third embodiment.

[0052] According to the third embodiment, the through-hole 33 of the plug 31 is tapered towards the side, where the coolant leaks the second type nozzle 21 . Fig. 6 is a cross-sectional view of the oil jet ring 19 through a second type nozzle 21 according to a fourth embodiment.

[0053] According to the fourth embodiment, the through-hole 33 of the plug 31 is choked.

[0054] Fig. 7 is a principle drawing of an embodiment of a vehicle 100.

[0055] The vehicle 100 comprises an electric drive 1 according to any of the afore-said embodiments.

[0056] The electric drive 1 is configured to propel the vehicle 100. The electric vehicle 100 comprises wheels 101 coupled with the electric drive 1 so as to rotate the wheels 101 . According to the embodiment, the electric vehicle 100 is a battery electric vehicle (BEV).

[0057] Alternatively, the electric vehicle 100 may additionally comprise a combustion engine, therein forming a hybrid vehicle.

[0058] Further, the electric vehicle 100 may comprise a fuel cell supplying the stator windings 9.

Claims

Claims1 . Electric drive (1 ) for a vehicle (100), the electric drive (1 ) comprising: an electric machine (3) having a stator (4), the stator (4) comprising a stator core (5) with an axial face side (6) and a stator winding (9) forming a winding head (10) at the face side (6);AC busbars (12) being arranged with an axial distance to the face side (6) and being connected to the stator winding (9) for supplying an AC voltage to the stator winding (9); and an oil jet ring (19) being attached to the face side (6) at a radial position more outwards than the winding head (10), the oil jet ring (19) comprising first type nozzles (20) being configured to jet a coolant towards the winding head (10); wherein the oil jet ring (19) further comprises second type nozzles (21 ) configured to jet the coolant towards the AC busbars (12).

2. Electric drive according to claim 1 , wherein the second type nozzles (21 ) are configured to jet the coolant away from the oil jet ring (19) into a direction having a larger axial component than a direction into which the first type nozzles (20) jet the coolant away from the oil jet ring (19).

3. Electric drive according to claim 1 or 2, wherein the oil jet ring (19) forms an attachment side (22) being attached to the face side (6), an inner side (23) facing the winding head (10) and an outer side (24) being opposite to the inner side (23), the first type nozzles (20) extending from the outer side (24) to the inner side (23).

4. Electric drive according to claim 3, wherein the oil jet ring (19) forms a fourth side (25) opposite to the attachment side (22), the second type nozzles (21 ) being arranged at the fourth side (25).

5. Electric drive according to claim 3 or 4, further comprisinga housing (16) forming a machine accommodation space (17), inside which the electric machine (3) is arranged, wherein the outer side (24) of the oil jet ring (19) and the housing (16) limit an annular fluid chamber (26) which supplies the coolant to the first type nozzles (20) and / or the second type nozzles (21 ).

6. Electric drive according to claim 5, wherein the machine accommodation space (17) and the stator core (5) limit a cooling jacket (27) for guiding the coolant circumferentially around the stator core (5), the cooling jacket (27) being configured to supply the coolant into the fluid chamber (26).

7. Electric drive according to any of the preceding claims, wherein the number of first type nozzles (20) is higher than the number of second type nozzles (21 ).

8. Electric drive according to any of the preceding claims, wherein the second type nozzles (21 ) are provided within a sector of at most 120 degrees, preferably at most 90 degrees, more preferably at most 60 degrees of the oil jet ring (19).

9. Electric drive according to any of the preceding claims, wherein each second type nozzle (21 ) is formed by an opening (28) of the oil jet ring (19) and a plug (31 ) inserted into the opening (28), the plug (31 ) comprising a shaft (32) and a trough-hole (33) extending through the shaft (32).

10. Electric drive according to claim 9, wherein at the side, where the coolant leaks the second type nozzle (21 ), the plug (31 ) extends out of the oil jet ring (19).11 . Electric drive according to claim 9 or 10, wherein the though-hole (33) is straight or tapered or choked.

12. Electric dive according to any claims 9 to 11 , wherein the plug (31 ) comprises a head (34), through which the through-hole (33) extends, the head (34) being arranged at a side of the oil jet ring (19) opposite to the side where the coolant leaks the second type nozzle (21 ).

13. Electric drive according to any of claims 9 to 11 , wherein the oil jet ring (19) comprises one or multiple further openings (29) corresponding to the openings, each further opening being closed by a blind plug (30).

14. Oil jet ring (19) for an electric drive (1 ), in particular for an electric drive (1 ) according to any of the preceding claims, wherein the oil jet ring forms (19) an attachment side (22), an inner side (23), an outer side (24) being opposite to the inner side (23), first type nozzles (20) extending from the outer side (24) to the inner side(23) and configured to jet a coolant away from the inner side (23) and second type nozzles (21 ) configured to jet the coolant away from the oil jet ring (19) into a direction having a larger axial component than a direction into which the first type nozzles (20) jet the coolant away from the oil jet ring (19).

15. Vehicle (100), comprising an electric drive (1 ) according to any of the preceding claims or an electric drive with an oil jet ring according to claim 14, the electric (1 ) drive being configured to propel the vehicle (100).

Images