ELECTRIC DRIVE ARRANGEMENT FOR A VEHICLE

Abstract

An electric drive arrangement for a vehicle includes a housing. The electric drive arrangement includes an electric machine with a stator connected to the housing and a rotor with a rotor shaft rotatably supported in the housing. The electric drive arrangement includes a transmission to transmit a rotary movement from the rotor shaft to drive a driveline of the vehicle. The electric drive arrangement includes a hydraulic circuit for circulating a fluid to cool and lubricate the electric machine and the transmission.

Claims

1.-14. (canceled)

15. An electric drive arrangement for a vehicle, the electric drive arrangement comprising: a housing; an electric machine with a stator connected to the housing and a rotor with a rotor shaft rotatably supported in the housing; a transmission to transmit a rotary movement from the rotor shaft to drive a driveline of the vehicle; and a hydraulic circuit for circulating a fluid to cool and lubricate the electric machine and the transmission, the hydraulic circuit comprising a bi-directional pump which on a suction side is hydraulically connected to an oil sump of the housing, a pump-actuated switch valve hydraulically connected to the bi-directional pump, a first hydraulic path connecting the switch valve with cooling nozzles of the electric machine, a second hydraulic path connecting the switch valve with a portion of the transmission, and a heat exchanger for cooling the fluid pumped by the bi-directional pump through the switch valve; wherein, operation of the bi-directional pump in a first direction of rotation transfers the switch valve into a first position in which fluid is pumped through the heat exchanger to the first hydraulic path for cooling the electric machine, and, operation of the bi-directional pump in a second direction of rotation transfers the switch valve into a second position in which fluid is pumped through the heat exchanger to the second hydraulic path for cooling and/or lubricating the transmission.

16. The electric drive arrangement according to claim 15, wherein the switch valve has a first inlet connected to a first pressure side of the bi-directional pump and a second inlet connected to a second pressure side of the bi-directional pump.

17. The electric drive arrangement according to claim 16, wherein the switch valve is actuated into the first position by pressurizing the first inlet and into the second position by pressurizing the second inlet.

18. The electric drive arrangement according to claim 16, wherein the switch valve has a first heat exchanger outlet hydraulically connected to the heat exchanger and a second heat exchanger outlet hydraulically connected to the heat exchanger, and wherein, fluid flows from the first inlet to the heat exchanger when the switch valve is in the first position, and, fluid flows from the second inlet to the heat exchanger when the switch valve is in the second position.

19. The electric drive arrangement according to claim 15, wherein the switch valve has a third inlet hydraulically connected to the heat exchanger, a first outlet to the first hydraulic path, and a second outlet to the second hydraulic path, and wherein fluid flows from the heat exchanger to the first outlet when the switch valve is in the first position and fluid flows from the heat exchanger to the second outlet when the switch valve is in the second position.

20. The electric drive arrangement according to claim 16, wherein operation of the bi-directional pump in the first direction of rotation pressurizes the first pressure side to a first pressure level and supplies fluid to the cooling nozzles for cooling stator end-windings of the stator.

21. The electric drive arrangement according to claim 20, wherein operation of the bi-directional pump in the second direction of rotation pressurizes the second pressure side to a second pressure level and supplies fluid for active cooling of the rotor and active lubrication of the transmission.

22. The electric drive arrangement according to claim 21, wherein the first pressure level is higher than the second pressure level.

23. The electric drive arrangement according to claim 15, wherein the second hydraulic path comprises a branch conduit connected to an inner diameter of the driveshaft.

24. The electric drive arrangement according to claim 15, wherein the driveshaft comprises radial bores connecting the inner diameter to the rotor for supplying the electric machine with fluid from the second hydraulic path in the high speed mode.

25. The electric drive arrangement according to claim 15, wherein the housing includes an intermediate wall which separates the oil sump into a motor-side reservoir and a transmission-side reservoir, wherein operation of the bi-directional pump in the first direction of rotation hydraulically connects the suction side to the motor-side reservoir, and operation of the bi-directional pump in a second direction of rotation is hydraulically connects the suction side to the transmission-side reservoir.

26. The electric drive arrangement according to claim 25, wherein the motor-side reservoir and the transmission-side reservoir are hydraulically connected via a through-opening of the intermediate wall.

27. The electric drive arrangement according to claim 15, wherein a suction filter is arranged between the oil sump and the bi-directional pump.

28. The electric drive arrangement according to claim 15, wherein a check valve is arranged between the oil sump and the bi-directional pump.

29. An electric drive arrangement for a vehicle, the electric drive arrangement comprising: a housing; an electric machine with a stator connected to the housing and a rotor with a rotor shaft rotatably supported in the housing; a transmission to transmit a rotary movement from the rotor shaft to drive a driveline of the vehicle; and a hydraulic circuit for circulating a fluid to cool and lubricate the electric machine and the transmission, the hydraulic circuit comprising a bi-directional pump which on a suction side is hydraulically connected to an oil sump of the housing, a pump-actuated switch valve hydraulically connected to the bi-directional pump, a first hydraulic path connecting the switch valve with cooling nozzles of the electric machine, a second hydraulic path connecting the switch valve with a portion of the transmission, and a heat exchanger for cooling the fluid pumped by the bi-directional pump through the switch valve; wherein, operation of the bi-directional pump in a first direction of rotation transfers the switch valve into a first position in which fluid is pumped through the heat exchanger to the first hydraulic path for cooling the electric machine, and operation of the bi-directional pump in a second direction of rotation transfers the switch valve into a second position in which=fluid is pumped through the heat exchanger to the second hydraulic path for cooling and/or lubricating the transmission; and wherein the switch valve has a first inlet connected to a first pressure side of the bi-directional pump and a second inlet connected to a second pressure side of the bi-directional pump.

30. An electric drive arrangement for a vehicle, the electric drive arrangement comprising: a housing; an electric machine with a stator connected to the housing and a rotor with a rotor shaft rotatably supported in the housing; a transmission to transmit a rotary movement from the rotor shaft to drive a driveline of the vehicle; and a hydraulic circuit for circulating a fluid to cool and lubricate the electric machine and the transmission, the hydraulic circuit comprising a bi-directional pump which on a suction side is hydraulically connected to an oil sump of the housing, a pump-actuated switch valve hydraulically connected to the bi-directional pump, a first hydraulic path connecting the switch valve with cooling nozzles of the electric machine, a second hydraulic path connecting the switch valve with a portion of the transmission, and a heat exchanger for cooling the fluid pumped by the bi-directional pump through the switch valve; wherein, operation of the bi-directional pump in a first direction of rotation transfers the switch valve into a first position in which fluid is pumped through the heat exchanger to the first hydraulic path for cooling the electric machine, and, when the bi-directional pump is operated in a second direction of rotation, the switch valve is transferred into a second position in which fluid is pumped through the heat exchanger to the second hydraulic path for cooling and/or lubricating the transmission; and wherein the second hydraulic path comprises a branch conduit connected to an inner diameter of the driveshaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments and further advantages of the electric drive arrangement for a vehicle will be illustrated as follows with reference to the accompanying drawings.

[0026] FIG. 1 shows a schematic illustration of an exemplary embodiment of the electric drive arrangement.

[0027] FIG. 2 shows a switch valve of the embodiment of FIG. 1 in a detailed schematic illustration, illustrating an operation of the bi-directional pump in a second direction of rotation.

[0028] FIG. 3 shows the switch valve of the embodiment of FIG. 1 in a detailed schematic illustration, illustrating an operation of the bi-directional pump in a second direction of rotation.

[0029] FIG. 4 shows a further exemplary embodiment of the electric drive arrangement in a schematic illustration.

DETAILED DESCRIPTION

[0030] In FIG. 1, an electric drive arrangement for a vehicle is depicted, wherein a housing 1, an electric machine 2, a transmission 3 and an oil sump 4 are shown as a schematic representation of a longitudinal cut along a rotary axis A of a rotor 10 of the electric machine 2. A hydraulic circuit 7 for circulating a fluid to cool and lubricate the electric machine 2 and the transmission 3 is in part schematically depicted. In FIG. 2, a switch valve 12 of the hydraulic circuit 7 of FIG. 1 is shown in a detailed schematic illustration, the switch valve 12 being set in a second position 26. In FIG. 3, the switch valve 12 of the hydraulic circuit 7 of FIG. 1 is shown in its first position 22. FIGS. 1, 2 and 3 will be described together.

[0031] The electric machine 2 has a stator 9 connected to the housing 1. The stator 9 includes stator end-windings 31. The rotor 10 is rotatable relative to the stator 9. A driveshaft 11 is connected to the rotor 10 and rotatably supported in the housing 1 about the axis of rotation A. The transmission 3 is adapted to transmit a rotary movement from the driveshaft 11 to drive a driveline of the vehicle, which is not depicted. The transmission 3 may comprise, for example, a reduction gear, a differential drive and a coupling, which are not depicted. The fluid of the hydraulic circuit 7 is gathered in the oil sump 4 formed in a lower portion of the housing 1. A bi-directional pump 24 is hydraulically connected to the oil sump 4 on a suction side via a fluid supply line 20. Between the oil sump 4 and the suction side of the bi-directional pump 24, a suction filter 25 is arranged for filtration of the fluid. The bi-directional pump 24 is further hydraulically connected to the pump-actuated switch valve 12. A first hydraulic path 14 connects the switch valve 12 with cooling nozzles 33 of the electric machine 2 and a second hydraulic path 15 connects the switch valve 12 with a portion of the transmission 3. A heat exchanger 35 is provided for cooling the fluid pumped by the bi-directional pump 24 through the switch valve 12. When the bi-directional pump 24 is operated in a first direction of rotation, the switch valve 12 is transferred into the first position 22 as shown in FIG. 3, in the first position 22 fluid is pumped through the heat exchanger 35 to the first hydraulic path 14 for cooling the electric machine 2. When the bi-directional pump 24 is operated in a second direction of rotation, the switch valve 12 is transferred into the second position 26 as shown in FIG. 2, in the second position 26 fluid is pumped through the heat exchanger 35 to the second hydraulic path 15 for cooling and/or lubricating the transmission 3.

[0032] According to the exemplary embodiment, the switch valve 12 may have a first inlet 38 connected to a first pressure side 23 of the bi-directional pump 24 and a second inlet 39 connected to a second pressure side 27 of the bi-directional pump 24. The respective first and second pressure sides 23, 27 depend on the direction of rotation of the bi-directional pump 24. When the bi-directional pump 24 is operated in the first direction of rotation, the first pressure side 23 is pressurized, which means that the second pressure side 27 becomes the suction side of the bi-directional pump 24. When the bi-directional pump 24 is operated in the second direction of rotation, the second pressure side 27 is pressurized and the first pressure side 23 becomes the suction side of the bi-directional pump 24. A check valve 29 between each of the first and second pressure sides 23, 27 and the fluid supply line 20 prevents a backflow towards the oil sump 4. The switch valve 12 comprises a valve housing 30 enclosing a void 32. Inside the valve housing 30 a valve spool 17 is actuated into the first position 22 by pressurizing the first inlet 38. The valve spool 17 is actuated into the second position 26 by pressurizing the second inlet 39. The switch valve 12 has a first heat exchanger outlet 41 hydraulically connected to the heat exchanger 35 and a second heat exchanger outlet 42 hydraulically connected to the heat exchanger 35. When the switch valve 12 is in the first position, fluid flows from the first inlet 38 to the heat exchanger 35 and, when the switch valve 12 is in the second position, fluid flows from the second inlet 39 to the heat exchanger 35. The switch valve 12 has a third inlet 40 hydraulically connected to the heat exchanger 35, a first outlet 43 to the first hydraulic path 14 and a second outlet 44 to the second hydraulic path 15. When the valve spool 17 of the switch valve 12 is in the first position 22, fluid flows from the heat exchanger 35 to the first outlet 43 and, when the valve spool 17 of the switch valve 12 is in the second position 26, fluid flows from the heat exchanger 35 to the second outlet 44. Hydraulically connected lines are shown with a dot representing a junction. Crossing lines without a junction dot are hydraulically separated. The fluid flow through the switch valve 12 is illustrated by arrows F for both the first position 22 in FIG. 3 and the second position 26 in FIG. 2.

[0033] When the bi-directional pump 24 is operated in the first direction of rotation, the first pressure side 23 is pressurized to a first pressure level to supply fluid to the cooling nozzles 33 for spray cooling of the stator end-windings 31 of the stator 9. The cooling nozzles 33 spray the fluid under high pressure towards the stator end-windings 31, from there the fluid flows back to the oil sump 4. A dotted line 36 represents a fluid level of the oil sump 4. Arrows F illustrate the flow of the fluid. The second hydraulic path 15 is not pressurized and no fluid is actively transported to the transmission 3, which is splash lubricated from the oil sump 4. The bi-directional pump 24 is operated in the first direction of rotation advantageously for low speed operation of the vehicle and lower rotation speed of the rotor 10 and rotating parts of the transmission 3.

[0034] When the bi-directional pump 24 is operated in the second direction of rotation, the second pressure side 27 is pressurized to a second pressure level to supply fluid for active cooling of the rotor 10 and active lubrication of the transmission 3. The second pressure level may be lower than the first pressure level. The second hydraulic path 15 comprises a branch conduit 8 connected to an inner diameter 18 of the driveshaft 11. The electric machine 2 is supplied with fluid from the second hydraulic path 15 via radial bores 21 of the driveshaft 11 connecting the inner diameter 18 with the rotor 10. The fluid is centrifuged along the rotor 10 towards the stator 9, and flows back into the oil sump 4 due to gravitational force, shown by arrows F. From the transmission 3, fluid runs back into the oil sump 4. The bi-directional pump 24 is advantageously operated in the second direction of rotation for high speed operation of the vehicle and high rotation speed of the rotor 10 and rotating parts of the transmission 3.

[0035] In FIG. 4, a second exemplary embodiment of the electric drive arrangement is shown in an identical schematic illustration as the first embodiment. Identical parts are denoted with the same reference numerals. The electric drive according to the second embodiment is further identical with regard to the housing 1, the electric machine 2, the transmission 3 and the reservoir 4, which are not described in detail again. Reference is made to the description above. As the switch valve 12 of the second exemplary embodiment can be identical to the switch valve 12 of the first embodiment, reference is further made to FIGS. 2 and 3, as described above.

[0036] The housing 1 includes an intermediate wall 16, which separates the reservoir 4 into a motor-side reservoir 5 and a transmission-side reservoir 6, which are connected via a through-opening 19 of the intermediate wall 16. The motor-side reservoir 5 and the transmission-side reservoir 6 are each hydraulically connected to the bi-directional pump 24 via two separate fluid supply lines 20, each connected to one possible suction side of the bi-directional pump 24, depending on the direction of rotation. Both fluid supply lines 20 comprise one of the two suction filters 25 for filtration of the fluid.

[0037] When the bi-directional pump 24 is operated in the first direction of rotation, the first pressure side 23 is pressurized and the motor-side reservoir 5 is hydraulically connected to the suction side of the bi-directional pump 24. When the switch valve 12 is at the first position 22, fluid is supplied via the first hydraulic path 14 to the cooling nozzles 33 for spray cooling of the stator end-windings 31 of the stator 9. The transmission 3 is splash lubricated from the transmission-side reservoir 6. A passage 37 in the intermediate wall 16 above the through-opening 19 allows fluid dripping off the transmission 3 to flow into the machine-side reservoir 5. Due to the through-opening 19, a fluid level 36 in the machine-side reservoir 5 is balanced with the fluid level in the transmission-side reservoir 6.

[0038] When the bi-directional pump 24 is operated in the second direction of rotation, the second pressure side 27 is pressurized and the transmission-side reservoir 6 is hydraulically connected to the suction side of the bi-directional pump 24. When the switch valve 12 is at the second position 22, fluid is supplied to the second hydraulic path 15 for active cooling of the rotor 10 and active lubrication of the transmission 3. A fraction of the fluid runs back from the transmission 3 through the passage 37 in the intermediate wall 16 into the machine-side reservoir 5. The fluid supplied to the rotor 10 also flows into the machine-side reservoir 5. As the fluid from the transmission-side reservoir 6 flows to the suction side of the bi-directional pump 24, the fluid level in the transmission-side reservoir 6 can advantageously be reduced. The flow through the through-opening 19, illustrated by the arrow F, can be adjusted by choosing an adequate diameter for through-opening 19. The diameter of through-opening 19 provides that the fluid level 36 of the machine-side reservoir 5 is higher than in the transmission-side reservoir 6 to advantageously keep churning losses low under high speed operation of the vehicle.

REFERENCE NUMERALS

[0039] 1 Housing [0040] 2 Electric machine [0041] 3 Transmission [0042] 4 Oil sump [0043] 5 Motor-side reservoir [0044] 6 Transmission-side reservoir [0045] 7 Hydraulic circuit [0046] 8 Branch conduit [0047] 9 Stator [0048] 10 Rotor [0049] 11 Driveshaft [0050] 12 Switch valve [0051] 14 First hydraulic path [0052] 15 Second hydraulic path [0053] 16 Intermediate wall [0054] 17 Spool [0055] 18 Inner diameter of the rotor shaft [0056] 19 Through-opening [0057] 20 Fluid supply line [0058] 21 Radial bore [0059] 22 First position [0060] 23 First suction side [0061] 24 Bi-directional pump [0062] 25 Filter [0063] 26 Second position [0064] 27 Second suction side [0065] 28 Junction [0066] 29 Check valve [0067] 30 Valve housing [0068] 31 Stator end windings [0069] 32 Void [0070] 33 Spray nozzles [0071] 34 Electric motor [0072] Heat exchanger [0073] 36 Fluid level [0074] 37 Passage [0075] 38 First inlet [0076] 39 Second inlet [0077] 40 Third inlet [0078] 41 First heat exchanger outlet [0079] 42 Second heat exchanger outlet [0080] 43 First outlet [0081] 44 Second outlet [0082] 45 A Rotary axis [0083] F Arrows