Drive unit for a drive train of an electrically drivable motor vehicle and drive arrangement having said drive unit

Abstract

A drive unit and a drive arrangement having the drive unit are provided. The drive unit includes a first electric machine and a second electric machine and an output shaft. A rotor of the second electric machine is connected to the output shaft for conjoint rotation and the drive unit has a separating clutch by which a rotor of the first electric machine is connected to the output shaft for torque transmission. The drive unit furthermore has a first flow system for implementing a flow of a first liquid for at least partial cooling of at least one electric machine and a second flow system for implementing a flow of a second liquid, the first flow system and the second flow system being arranged such that heat from the first liquid in the first flow system is transferred to the second liquid in the second flow system.

Claims

1. A drive unit for a drive train of an electrically drivable motor vehicle, the drive unit comprising: a first electric machine having a rotor; a second electric machine having a rotor; an output shaft, the rotor of the second electric machine is connected to the output shaft for conjoint rotation therewith; a separating clutch by which the rotor of the first electric machine is connectable to the output shaft for torque transmission; a first flow system for implementing a flow of a first liquid for at least partial cooling of at least one of the first or second electric machines, wherein the first flow system is further configured such that the first liquid is fed through a line to the separating clutch for at least one of cooling or lubrication; and a second flow system for implementing a flow of a second liquid, wherein the first flow system and the second flow system are configured such that heat from the first liquid in the first flow system is transferrable to the second liquid in the second flow system.

2. The drive unit according to claim 1, further comprising a heat exchanger configured for transferring heat from the first liquid to the second liquid.

3. The drive unit according to claim 1, wherein the line in which the first liquid is fed through is integrated in a housing, the first electric machine and the second electric machine being arranged at least partially within the housing.

4. The drive unit according to claim 1, wherein the first flow system and the separating clutch are configured such that the first liquid is feedable from the first flow system to the separating clutch for hydraulic actuation thereof.

5. The drive unit according to claim 4, further comprising a volumetric flow source, a hydraulic clutch actuator as an actuation system for actuating the separating clutch, and a switching device with which a liquid volumetric flow provided by the volumetric flow source is adapted to be fed sequentially to the electric machines or the clutch actuator.

6. The drive unit according to claim 1, wherein the separating clutch is configured to be electromechanically actuatable.

7. The drive unit according to claim 1, wherein the first flow system has a branch into a first cooling path and into a second cooling path, so that the at least one of the first or second electric machine is adapted to be cooled in a radial interior formed by the rotor thereof and also on a radial outer side thereof.

8. A drive arrangement comprising: a drive unit according to claim 1; and an internal combustion engine which is couplable to the rotor of the first electric machine for conjoint rotation therewith.

9. The drive arrangement according to claim 8, further comprising a transmission or an input element of a wheel drive, wherein the internal combustion engine is mechanically connectable via the drive unit to the transmission or the input element of the wheel drive via the separating clutch of the drive unit.

10. The drive arrangement according to claim 9, further, comprising, between the internal combustion engine and a first shaft which is connected to the rotor of the first electric machine for conjoint rotation, a first transmission stage configured for stepping up a speed of a rotary movement realized by the internal combustion engine on the first shaft.

11. A drive unit for a drive train of an electrically drivable motor vehicle, the drive unit comprising: a first electric machine having a rotor; a second electric machine having a rotor; an output shaft, the rotor of the second electric machine is connected to the output shaft for conjoint rotation therewith; a separating clutch by which the rotor of the first electric machine is connectable to the output shaft for torque transmission; a first flow system configured to implement a flow of a first liquid for at least partial cooling of at least one of the first or second electric machines, wherein the first flow system is further configured to selectively feed the first liquid to the separating clutch for hydraulic actuation thereof; a second flow system configured to implement a flow of a second liquid; and a heat exchanger that transfers heat from the first liquid in the first flow system to the second liquid in the second flow system.

12. The drive unit according to claim 11, wherein the first flow system is further configured such that the first liquid is feedable to the separating clutch for at least one of cooling or lubrication.

13. The drive unit according to claim 11, further comprising a volumetric flow source, a hydraulic clutch actuator as an actuation system for actuating the separating clutch, and a switching device with which a liquid volumetric flow provided by the volumetric flow source is adapted to be fed sequentially to the electric machines or the clutch actuator.

14. The drive unit according to claim 11, wherein the separating clutch is electromechanically actuatable.

15. The drive unit according to claim 11, wherein the first flow system has a branch into a first cooling path that is configured to cool a radial interior of the at least one of the first or second electric machines and into a second cooling path is configured to cool a radial exterior of the at least one of the first or second electric machines.

16. A drive arrangement comprising: a drive unit according to claim 11; and an internal combustion engine which is couplable to the rotor of the first electric machine for conjoint rotation therewith.

17. The drive arrangement according to claim 16, further comprising a transmission or an input element of a wheel drive, wherein the internal combustion engine is mechanically connectable via the drive unit to the transmission or the input element of the wheel drive via the separating clutch of the drive unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The embodiments described above is explained in detail below based on the relevant technical background with reference to the associated drawings, which show preferred embodiments. The invention is in no way restricted by the purely schematic drawings, although it should be noted that the embodiments shown in the drawings are not limited to the dimensions shown. In the figures:

(2) FIG. 1: shows a drive arrangement according to an embodiment in a sectional view,

(3) FIG. 2: shows a side view of the drive arrangement,

(4) FIG. 3: shows a sectional view of a partial area of the drive arrangement from above,

(5) FIG. 4: shows a sectional view of a partial area of the drive arrangement from the side, and

(6) FIG. 5: shows an enlarged view of an area of the sectional view shown in FIG. 4.

DETAILED DESCRIPTION

(7) FIG. 1 shows a drive unit 100 for a drive train of an electrically drivable motor vehicle, in particular a hybrid vehicle, which has a first electric machine 110 and a second electric machine 120, both of which are arranged on a common axis of rotation 101. The rotor 111 of the first electric machine 110 is arranged coaxially to the axis of rotation 101 and also to the rotor 121 of the second electric machine 120. The stator 112 of the first electric machine 110 and also the stator 122 of the second electric machine 120 are accommodated in a housing 102 of the drive unit 100.

(8) The rotor 111 of the first electric machine is connected to a first shaft 130 for conjoint rotation. The rotor 121 of the second electric machine 120 is connected to an output shaft 140 for conjoint rotation, which can also be referred to as a transmission input shaft.

(9) Furthermore, the drive unit 100 comprises a separating clutch 150 with which the first electric machine 110 and thus an internal combustion engine connected to the first shaft 130 connected for conjoint rotation to the rotor 111 of the first electric machine 110 can be or is connected to the output shaft for torque transmission.

(10) In the embodiment shown here, the first shaft 130 is designed in two parts, namely made up of a central hollow shaft 132 and a hub 133 positioned on this hollow shaft 132 and connected thereto for conjoint rotation, wherein the hub 133 is also connected to the rotor 111 of the first electric machine 110 in a fixed manner.

(11) The hub 133 forms the radial inner side 151 of the separating clutch 150 or is firmly connected to this input side of the separating clutch 150.

(12) The radial outer side 152 of the separating clutch 150, which realizes the output side of the separating clutch 150, is connected to the output shaft 140 for conjoint rotation.

(13) The separating clutch 150 is a switchable clutch that can be switched from an open state to a closed state and vice versa. For this purpose, the separating clutch 150 is assigned an actuation system 153.

(14) In this way, when the separating clutch 150 is closed, a torque can be transmitted from the first shaft 130 to the output shaft 140 or vice versa.

(15) In the embodiment shown here, it is thus provided that the two electric machines 110, 120 are arranged in series, wherein the rotors 111, 121 of the two electric machines 110, 120 or their axes of rotation are arranged coaxially.

(16) The first shaft 130 or its central hollow shaft 132 runs radially inside the output shaft 140, whereby the overall volume required for the drive unit 100 can be kept small.

(17) Furthermore, the drive unit 100 shown here comprises a transmission 160 which is in operative connection with the output shaft 140 of the drive unit 100, also referred to as the transmission input shaft, so that a torque made available by the output shaft 140 or the rotary movement realized by the output shaft 140 can be directed stepped up or stepped down via the transmission 160 to a further transmission unit of a motor vehicle, or can also be directed directly to drive wheels of a motor vehicle.

(18) In the embodiment shown here, this transmission 160 comprises a differential transmission 170.

(19) Furthermore, the transmission 160 comprises a first gearwheel 161, which meshes with an external toothing 141 on the output shaft 140. A second transmission stage 162 is thus realized in the drive unit 100 by the first gearwheel 161. This first gearwheel 161 is coupled to a countershaft 163 of the gear 160 for conjoint rotation, the external toothing 164 of which in turn meshes with an input gear 171 of the differential gear 170, thereby realizing a third transmission stage 172.

(20) The drive unit 100 is part of a likewise illustrated embodiment of a drive arrangement 200 according to an embodiment.

(21) This drive arrangement 200 additionally has an internal combustion engine (not shown here) which, when connected to the connection 210 shown, is coupled to the rotor 111 of the first electric machine 110 for conjoint rotation via the first shaft 130 orwith the interposition of a further couplingcan be coupled thereto.

(22) The illustrated drive arrangement 200 is designed in such a way that a first transmission stage 142 is formed between the connection 210 for an internal combustion engine (not shown here) and the first shaft 130, which is connected to the rotor 111 of the first electric machine 110 for conjoint rotation, for the purpose of stepping up the speed of the rotary movement realized by the internal combustion engine or its connection 210 on the first shaft 130.

(23) For this purpose, an output element 220 of the internal combustion engine is provided, which can have a damper unit 221 or a clutch 222 for opening and closing the torque transmission path between the internal combustion engine and the drive unit 100, or a combination shown of a damper unit 221 and a clutch 222.

(24) Furthermore, the output element 220 comprises an internally toothed gearwheel 223 as a component, which meshes with an external toothing 131 of the first shaft 130 and thus realizes a first transmission stage 142.

(25) It can be seen that, in the exemplary embodiment shown here, an axis of rotation of the output element 220 is offset laterally to the axis of rotation 101 of the drive unit 100.

(26) In this way, a rotary movement generated by the internal combustion engine (not shown here) can be directed via the output element 220 and the first transmission stage 142 on the first shaft 130, so that the rotor 111 of the first electric machine 110 located thereon can be set in rotary movement in order to operate as a generator.

(27) When the separating clutch 150 closes, the applied rotary movement can be transmitted from the first shaft 130, possibly amplified by an electric motor drive through the first electric machine 110, to the output shaft 140. Because of the conjointly rotating connection of the rotor 122 of the second electric machine 120 to the output shaft 140, a torque provided by the second electric machine 120 can also be applied to the output shaft 140.

(28) Alternatively, when the separating clutch 150 is opened, only the second electric machine 120 can be operated alone in order to rotate the output shaft 140.

(29) The rotary movement of the output shaft 140 is directed via its external toothing 141 to the first gear 161 of the connected gear 160, wherein the second transmission stage 162 is realized.

(30) From the first gear 161, the torque or the rotary movement is directed to the countershaft 163, from which it is transferred to the differential transmission 170 via the input gearwheel 171.

(31) The torque is transferred from the differential transmission 170 to the wheel drive shafts (not shown here) or, if necessary, a further transmission to step up or down the torque or the speed.

(32) The illustrated drive arrangement 200 can realize a wide variety of driving states, such as operation of the internal combustion engine alone to drive a motor vehicle, or with the addition of the second electric machine and/or the first electric machine, as well as simultaneous generator operation of the first electric machine during operation of the internal combustion engine and/or the second electric machine, as well as operation of the second electric machine alone, or recuperation operation of the first electric machine and/or the second electric machine.

(33) A hydraulic unit 1 and the flow systems 10, 20 connected thereto and their components are substantially shown in FIGS. 2-5.

(34) FIG. 2 shows, in a view from the side, a hydraulic unit 1 as a compact unit in which a volumetric flow source 50 (not shown in detail), in particular a pump, and a hydraulic control unit 60 (also not shown in detail) are arranged. The hydraulic unit 1 is accommodated in a common housing 102, which at the same time is also a housing of the second electric machine 120.

(35) The hydraulic unit 1 comprises a connection for a cooling line 13, with which coolant can be conducted to the unit to be cooled, as well as a connection for an actuation line 90, with which a liquid for actuation of the separating clutch can be conducted.

(36) Furthermore, two cooling water connections 22 can be seen in FIG. 2 for supplying a liquid for the second flow system.

(37) In the lower area, an oil filter 80 can be seen, which is located in an oil sump 81, which represents a storage device for the liquid to be used. An intermediate line 30 leads from this sump 81 to the hydraulic unit 1 in order to supply it with liquid.

(38) The hydraulic unit 1 or the volumetric flow source 50 or pump integrated therein sucks in liquid through the oil filter 80. The volumetric flow source 50 then sets the volumetric flow of the liquid through the hydraulic control unit (not shown here), according to the requirement for cooling an electric machine and/or bearings, gearwheels and the required actuation pressure for activating the separating clutch. By arranging the hydraulic unit in the upper region of the drive arrangement, the installation space within the housing 102 is optimally used.

(39) FIG. 3 also shows a region of the drive arrangement according to a embodiment in a sectional view from above, wherein the second transmission stage 162 is clearly visible here.

(40) The hydraulic system 1 to which the cooling line 13 is connected as part of the first flow system 10 is also shown here. In the embodiment shown here, oil 3 can be transported as a liquid through the cooling line 13.

(41) The volume flow of this liquid reaches a heat exchanger 40 designed as a heat exchanging device, where the liquid flows into an inlet 41 after it has absorbed heat from an electric machine. The liquid flows through the heat exchanger 40 and exits an outlet 42 cooled, since it has transferred heat in the heat exchanger 40 to the liquid, in this case water 4, in the second flow system 20. The second flow system 20 thus serves as a cooling water circuit. The liquid in the second flow system 20 flows in a cooling water line 21. It is provided and fed to the hydraulic system 1 via cooling water connections 22.

(42) As a result of the heat transfer from an electric machine to the liquid, the respective electric machine can be operated in an optimal temperature range and consequently with a relatively high degree of efficiency.

(43) The liquid of the first flow system 10 passes after the outlet 42 to a distribution line 14, which enables the liquid to be distributed in the housing 102.

(44) FIG. 4 shows flow paths of the cooling medium in a sectional view. The most important units of the drive arrangement on a common axis of rotation 2 are shown here. It can be seen that the flow of the liquid for cooling is divided at several branches 70 in order to be fed to several electric machines 110, 120 and to be able to cool at least the inner side and outer side of the first electric machine 110. This results in a first path 71 for the cooling medium and a second path 72. In particular, via the second path 72, the cooling medium can reach an interior 73 of the first electric machine 110 via the hub 133 on which the rotor 111 of the first electric machine 110 is seated, which is formed by the rotor or also by the stator of the first electric machine 110.

(45) A further branch 70 enables cooling 15 of the stator of the first electric machine 110 to be implemented, and cooling of the state of the second electric machine 120 to be implemented by cooling 16.

(46) To guide the cooling medium from a radial outer side of the two electric machines 110, 120 to the radial inner side, an intermediate line 30 is provided arranged axially on the outside in the embodiment shown here, which forms part of the line system between the oil filter and the hydraulic unit. On the radial inner side, the centrifugal force caused by the rotation ensures that the coolant is distributed.

(47) When the cooling medium has flowed around an electric machine in such a way that it is again on the radial outer side of the electric machine, it can be guided back to the oil sump 81 through a return flow 32.

(48) In addition to cooling individual units, the hydraulic system can also be configured to actuate the separating clutch 150. The flow system required for this is shown in FIG. 5.

(49) The actuation line 90, which serves to guide oil 3 as a pressure medium, is integrated in the housing 102. This pressure medium is fed to the actuation system 153, which is designed as a hydraulic actuator. When a corresponding pressure is applied, the actuation system 153 causes the separating clutch 150 to close or open.

(50) With the drive unit proposed here and the drive arrangement equipped with same, devices for electrically drivable motor vehicles are provided, the individual components of which can be optimally cooled so that they can be operated with a long service life or with optimal efficiency.

LIST OF REFERENCE SYMBOLS

(51) 1 Hydraulic unit 2 Axis of rotation 3 Oil 4 Water 10 First flow system 13 Cooling line 14 Distribution line 15 Cooling of the stator of the first electric machine 16 Cooling of the stator of the second electric machine 20 Second flow system 21 Cooling water line 22 Cooling water connection 30 Intermediate line 31 Outer line 32 Return flow in the oil sump 40 Heat exchanger 41 Inlet for heated liquid 42 Outlet for cooled liquid 50 Volumetric flow source 60 Hydraulic control unit 70 Branch 71 First cooling path 72 Second cooling path 73 Interior 80 Oil filter 81 Oil sump 90 Actuation line 100 Drive unit 101 Axis of rotation 102 Housing 110 First electric machine 111 Rotor of the first electric machine 112 Stator of the first electric machine 120 Second electric machine 121 Rotor of the second electric machine 122 Stator of the second electric machine 130 First shaft 131 External toothing of the first shaft 132 Central hollow shaft 133 Hub 140 Output shaft 141 External toothing of the output shaft 142 First transmission stage 150 Separating clutch 151 Radial inner side of the separating clutch 152 Radial outer side of the separating clutch 153 Actuation system 160 Transmission 161 First gearwheel 162 Second transmission stage 163 Countershaft 164 External toothing of the countershaft 170 Differential transmission 171 Input gearwheel 172 Third transmission stage 200 Drive arrangement 210 Connection for an internal combustion engine 220 Output element 221 Damper unit 222 Clutch 223 Internally toothed gearwheel