Electric drive device for a vehicle

Abstract

1. An electric drive for a vehicle comprising: an electric machine including a housing, a stator connected to the housing and including stator end windings, a rotor rotatable relative to the stator, and a drive shaft connected to the rotor and rotatably supported within the housing about an axis of rotation; a transmission for transmitting rotational motion from the drive shaft to drive a driveline of the vehicle; and a hydraulic circuit for circulating a fluid.

Description

Technical Field

[0001] The present invention relates to an electric drive device for a vehicle having a housing, an electric machine, a transmission, and a hydraulic circuit for circulating a fluid.

[0002] European Patent Application Publication No. 3517335 discloses an electric vehicle including a power control unit, a drive motor, a first cooling channel in which a first coolant cooled in a first heat exchanger is flowed through the power control unit and a second heat exchanger in this order and then returned to the first heat exchanger, and a second cooling channel in which a second coolant cooled by the first coolant in the second heat exchanger is flowed through the drive motor and then returned to the second heat exchanger, and a second pump is attached. The second pump starts or stops the circulation of the second coolant, or increases or decreases the circulation amount of the second coolant based on one or both of the temperature of the power control unit and the temperature of the first coolant.

[0003] U.S. Patent Application Publication No. 2018 / 241288 discloses a cooling structure for a rotating electric machine that cools a stator and a rotor by supplying a cooling medium to the stator and the rotor of the rotating electric machine by a pump, including a first passage for supplying the cooling medium from the pump to the stator, a second passage for supplying the cooling medium from the pump to the rotor, and a valve for adjusting the flow of the cooling medium in the first passage and the flow of the cooling medium in the second passage, and the cooling state of the stator and the cooling state of the rotor are controlled by the valve.

[0004] From U.S. Patent Application Publication No. 2019 / 0229582, there is known a vehicle drive device including a lubrication path including a first oil pump that pumps up oil stored in a casing and supplies it to a power transmission mechanism to lubricate the power transmission mechanism, and a cooling path that is separated from the lubrication circuit and provided in a rotating electrical machine, the cooling path including a second oil pump that pumps up oil stored in the casing and supplies it only to the rotating electrical machine to cool the rotating electrical machine, the second oil pump being an electric oil pump, and an oil cooler that cools the oil supplied to the rotating electrical machine being provided in the cooling path.

[0005] U.S. Patent Application Publication No. 2016 / 0178548 discloses a method for dynamically monitoring the temperature of a fluid in a heat generating device, the method including using a temperature sensor to monitor the temperature of the fluid held in a fluid sample. A first fluid flow rate and a second fluid flow rate are determined. Based on the temperature of the fluid passing through an active coolant circuit and a third fluid flow rate, a third fluid flow rate and a temperature drop of the fluid across the heat exchanger in the active coolant circuit are determined. The fluid temperature supplied to the electrical machine via the active coolant circuit is determined based on the third fluid flow rate and the temperature drop of the fluid across the heat exchanger. The effective temperature of the fluid is determined based on the temperature of the fluid in the sample and the temperature of the fluid supplied to the electrical machine through the active coolant circuit.

[0006] The electrical machine and the transmission of an electric drive device for a vehicle have different cooling requirements and lubrication requirements depending on the operating conditions. The performance of the electrical machine is thermally limited during operation. There may be inherent losses in the copper, iron, and magnets of the electric motor, and the temperature of each component and structure is limited by the material properties. Effective cooling is necessary to achieve sufficient torque performance. The passive splash lubrication of the transmission causes churning losses under high-speed operation. The combination of cooling and lubrication for both the electrical machine and the transmission is a compromise in terms of efficiency.

[0007] Accordingly, an object of the present invention is to propose an electric drive device for a vehicle having a hydraulic circuit for circulating a fluid for efficient cooling and lubrication of an electric machine and a transmission.

[0008] This object is achieved by an electric drive device for a vehicle, a housing, an electric machine including a stator connected to the housing and including a stator end winding, a rotor rotatable relative to the stator, and a drive shaft connected to the rotor and rotatably supported in the housing about a rotation axis, a transmission that transmits a rotational movement from the drive shaft to drive a drive line of the vehicle, a hydraulic circuit for circulating a fluid, the hydraulic circuit comprising a pump hydraulically connected to a reservoir, a mode control valve hydraulically connected to the pump, a hydraulic stator path connecting the mode control valve to a part of the electric machine to supply fluid to the stator, and a hydraulic transmission path connecting the mode control valve to a part of the transmission and is solved by an electric drive device comprising the same.

[0009] The mode control valve is controllable such that in a low-speed mode, fluid is supplied to the stator end winding of the electric machine via the hydraulic stator path, and in a high-speed mode, fluid is supplied to the transmission via the hydraulic transmission path.

[0010] The advantage of the electric drive is that the two modes of the hydraulic circuit can optimize the cooling and lubrication of the electromechanical and transmission. The high-speed mode can advantageously be applied to the high-speed operation of the vehicle, and thus to the high rotational speeds of the rotor and transmission components. The low-speed mode can advantageously be applied to the low-speed operation of the vehicle, and thus, compared to the high-speed mode, to the low rotational speeds of the rotor and transmission components. The fluid circulating within the hydraulic circuit is a cooling and lubricating fluid such as, for example, oil. The reservoir may also be referred to as an oil sump arranged to collect the fluid dripping from the electromechanical and transmission due to gravity.

[0011] In the low-speed mode, high torque requirements are common and copper losses occur due to high current. Therefore, by supplying fluid to the stator end windings of the electromechanical via the hydraulic stator path in the low-speed mode, the stator end windings are effectively cooled, and thus the losses are reduced. In the low-speed mode, high-pressure spray cooling of the winding heads is possible, and the lubrication of the transmission in the low-speed mode does not require an active fluid supply. Since the churning losses are low at low rotational speeds, passive splash lubrication of the transmission is effective in the low-speed mode.

[0012] In the high-speed mode, since the torque requirement of the electromechanical is low, spray cooling of the winding heads is unnecessary. Instead, active lubrication of the transmission components operating at high speed can advantageously be achieved by supplying fluid via a hydraulic transmission path to a part of the transmission, which means that not all components or parts of the transmission are supplied via the hydraulic transmission path. For example, the final drive can still be passively splash lubricated.

[0013] According to one embodiment, the housing can include an intermediate wall that separates the reservoir into a motor-side reservoir and a transmission-side reservoir, and the reservoir control valve is disposed in the through-opening of the intermediate wall to selectively open or close the through-opening. The motor-side reservoir collects the fluid dripping from the electromechanical machine and a part of the fluid dripping from the transmission. The transmission-side reservoir collects a part of the fluid dripping from the transmission. The reservoir control valve can be advantageously controllable such that the through-opening is opened in the low-speed mode and closed in the high-speed mode. When the through-opening is open, the liquid levels of the motor-side reservoir and the transmission-side reservoir are balanced, and the transmission-side reservoir contains sufficient fluid to passively splash-lubricate the transmission. When the through-opening is closed, the liquid level of the motor-side reservoir rises, and as a result, the liquid level of the transmission-side reservoir drops, thereby reducing, for example, the churning losses of the final drive that can still be passively lubricated in the high-speed mode. In the low-speed mode, the transmission is supplied with fluid only passively from the transmission-side reservoir, and the liquid level in the transmission-side reservoir in the low-speed mode is higher than in the high-speed mode.

[0014] According to a further embodiment, the hydraulic transmission path comprises a branch conduit to the inner diameter portion of the drive shaft. Since the active lubrication of the transmission does not require the supply of high-pressure fluid, in the high-speed mode, a low-pressure coolant fluid can be supplied to the electromechanical machine via the drive shaft. In the high-speed mode, the fluid is supplied to the electromechanical machine through the radial bore of the drive shaft that connects the inner diameter portion to the rotor. The rotor is cooled, and the fluid is further centrifuged towards the stator and the stator end windings, thus also cooling the stator end windings.

[0015] According to a further embodiment, the mode control valve is a 3-port 2-position valve that is in the normal position in the high-speed mode and in the actuated position in the low-speed mode. The normal position is the position where the valve returns without external actuation, which can be achieved, for example, by a biasing spring. Advantageously, in the case of a malfunction of the mode control valve, the mode control valve remains in the high-speed mode, providing sufficient lubrication for the transmission operating at high speed and thus preventing damage. On the other hand, the lack of high-pressure spray cooling of the stator end windings under low-speed conditions is accompanied by no damage but only higher losses. Therefore, the reservoir control valve can be a 2-port 2-position valve that is in the normal position, i.e., the closed position, in the high-speed mode and in the actuated position, i.e., the open position, in the low-speed mode in at least one embodiment.

[0016] According to one embodiment, the mode control valve can be actuated electromagnetically, and thus the low-speed mode and the high-speed mode are set by an external current driving the electromagnet of the mode control valve. The reservoir control valve can advantageously be actuated hydraulically depending on the position of the mode control valve. For example, a hydraulic line can connect the reservoir control valve to the hydraulic stator path. When fluid is supplied to the hydraulic stator path in the low-speed mode, the reservoir control valve is actuated from the normal position to the actuated position by the pressure in the hydraulic stator path via the hydraulic line, thereby opening the through-hole.

[0017] According to an alternative embodiment, the mode control valve can be hydraulically actuated and the pump is a bidirectional pump. Whether the mode control valve is actuated or not can be determined according to the pumping direction of the pump. By one pumping direction of the pump, the mode control valve is actuated, i.e., it reaches the operating position for the low-speed mode. By switching the pump to the reverse pumping direction, the mode control valve can be returned to its normal position for the high-speed mode. The fluid supply line that hydraulically connects the reservoir to the pump can be split into two branches upstream of the pump. The first of the two branches is connected to the first suction side inlet of the pump in the high-speed mode, and the second of the two branches is connected to the second suction side inlet of the pump in the low-speed mode. It is clear that the first suction side inlet of the pump becomes the pressure outlet of the pump in the low-speed mode, and the second suction side inlet of the pump becomes the pressure outlet of the pump in the high-speed mode. In order to supply fluid from each pressure outlet to the mode control valve further, the two branches can rejoin at a junction downstream of the pump and upstream of the mode control valve.

[0018] According to a further embodiment, the two branches comprise a check valve device that establishes a fluid flow in the high-speed mode from the first branch to the first suction side inlet, further through the pump to the second branch, and further to the junction. In the low-speed mode, the fluid flow is established from the second branch to the second suction side inlet, further through the pump to the first branch, and further to the junction. The check valve device can comprise two check valves for each of the two branches, and each first suction side inlet and second suction side inlet is located between each of the two check valves of the branch respectively. The check valve device may be further adapted to allow flow only in the direction from the reservoir towards the junction through each of the two branches.

[0019] The hydraulic-actuated mode control valve can include a hydraulic line connected to the first branch so as to be hydraulically actuated by the pressure in the first branch. The mode control valve is actuated, i.e., shifted to the actuated position, when fluid is supplied from the pressure outlet of the pump to the first branch in the low-speed mode. When the pumping direction of the pump is reversed for the high-speed mode, the first branch is connected to the first suction-side inlet of the pump, and as a result, the mode control valve returns to the normal position.

[0020] In this embodiment, the hydraulic-actuated reservoir control valve can be actuated via a hydraulic line connected to the first branch.

[0021] Exemplary embodiments and further advantages of an electric drive device for a motor vehicle will be described below with reference to the accompanying drawings.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0023] Figure 1 shows an electric drive device for a motor vehicle, with the housing 1, the electric machine 2, the transmission 3 and the reservoir 4 shown as a schematic longitudinal section along the axis of rotation A of the rotor 10 of the electric machine 2. The electric machine 2 has a stator 9 connected to the housing 1 and including a stator end winding 31, and a rotor 10 rotatable relative to the stator 9. A drive shaft 11 is connected to the rotor 10 and is rotatably supported within the housing 1 about the axis of rotation A. The transmission 3 is adapted to transmit the rotational movement from the drive shaft 11 and drive a vehicle drive line (not shown). The transmission 3 can comprise, for example, a reduction gear, a differential drive and a coupling (not shown). A hydraulic circuit 7 is schematically shown, which has a pump 24 hydraulically connected to the reservoir 4 via a fluid supply line 20, a mode control valve 12 hydraulically connected to the pump 24, a hydraulic stator path 14 connecting the mode control valve 12 to a part of the electric machine 2 to supply fluid to the stator 9, and a hydraulic transmission path 15 connecting the mode control valve 12 to a part of the transmission 3. The mode control valve 12 is controllable such that in the low speed mode fluid is supplied to the stator end winding 31 of the electric machine 2 via the hydraulic stator path 14, and in the high speed mode fluid is supplied to the transmission 3 via the hydraulic transmission path 15. The two modes of the hydraulic circuit 7 provide optimized cooling and lubrication of the electric machine 2 and the transmission 3 depending on the operating conditions of the electric drive device. The pump 24 is driven by an electric motor 34. A suction filter 25 is arranged upstream of the pump 24, and downstream of the pump 24 the fluid can be cooled in a heat exchanger 35.

[0024] The housing 1 includes an intermediate wall 16 that separates the reservoir 4 into a motor-side reservoir 5 and a transmission-side reservoir 6, and a reservoir control valve 17 is disposed in the through-opening 19 of the intermediate wall 16 to selectively open or close the through-opening 19. In the low-speed mode, fluid is passively supplied to the transmission 3 from the transmission-side reservoir 6. In the low-speed mode, the liquid level of the transmission-side reservoir 6 rises and sufficient splash lubrication is performed. On the other hand, in the high-speed mode, the liquid level of the transmission-side reservoir 6 drops and the churning loss is kept low. The hydraulic transmission path 15 includes a branch conduit 8 to the inner diameter portion 18 of the drive shaft 11 in order to supply cooling fluid to the electromechanical machine 2 even in the high-speed mode. The cooling fluid is introduced through the radial bore 21 of the drive shaft 11 that connects the inner diameter portion 18 to the rotor 10. The fluid is centrifugally separated along the rotor 10 toward the stator 9 including the stator end winding 31 and flows back to the machine-side reservoir 5 by gravity.

[0025] In the illustrated embodiment, the mode control valve 12 is an electromagnetically actuated 3-port 2-position valve. The reservoir control valve 17 is a hydraulically actuated 2-port 2-position valve connected via a hydraulic line 30 to the hydraulic stator path 14. Therefore, the operation of the reservoir control valve 17 depends on the operating mode determined by the position of the mode control valve 12.

[0026] Next, the low-speed mode will be described with reference to FIG. 2. FIG. 2 shows the electric drive device of FIG. 1 with the hydraulic circuit 7 in the low-speed mode. Hydraulically connected lines are shown at points representing junction points. Lines that cross without a junction point are hydraulically separated. Hydraulic connection lines that are not pressurized and do not supply fluid by the pump 24 are shown by dashed lines, while solid lines represent pressurized connection lines that supply fluid in the low-speed mode. In the low-speed mode, the mode control valve 12 is in an operating position that acts against the spring 32 that biases the mode control valve 12 to its normal position by the applied electromagnetic force. In the low-speed mode, the mode control valve 12 directs the fluid flow from the pump 24 to the hydraulic stator path 14, and the hydraulic stator path 14 supplies the fluid under high pressure to the spray nozzle 33 so as to spray the fluid toward the stator end winding 31 of the electromechanical machine 2, and from there the fluid flows back to the machine-side reservoir 5. The arrow F indicates the flow of fluid into the machine-side reservoir 5. The passage 37 in the intermediate wall 16 above the through-opening 19 also allows the fluid dripping from the transmission 3 to flow into the machine-side reservoir 5. However, in the low-speed mode, since the through-opening 19 is open, the liquid level 36 in the machine-side reservoir 5 is balanced with the liquid level in the transmission-side reservoir 6. The reservoir control valve 17 is a two-port two-position valve and is in its operating position in the low-speed mode, and thus the through-opening 19 is open. The hydraulic line 30 connected to the hydraulic stator path 14 is pressurized when the fluid flow is directed to the hydraulic stator path 14 by the mode control valve 12. The hydraulic transmission path 15 is not pressurized, and the fluid splash-lubricated from the transmission-side reservoir 6 is not actively transported to the transmission 3. The low-speed mode can advantageously be applied to the low-speed operation of the vehicle, and thus to the lower rotational speeds of the rotor 10 and the rotating parts of the transmission 3.

[0027] Next, the high-speed mode will be described with reference to FIG. 3. FIG. 3 shows the electric drive device of FIG. 1 in which the hydraulic circuit 7 is in the high-speed mode. The mode control valve 12 does not operate in the high-speed mode and is held in its normal position by the biasing spring 32. In the high-speed mode, the mode control valve 12 directs the fluid flow from the pump 24 to the hydraulic transmission path 15, and the hydraulic transmission path 15 actively supplies lubricating fluid to the transmission 3. The branch conduit 8 of the hydraulic transmission path 15 also supplies fluid to the inner diameter portion 18 of the drive shaft 11 of the electromechanical machine 2 for cooling. The fluid returns from the transmission 3 to the reservoir 4, a part of which flows to the transmission-side reservoir 6, and the other part flows to the machine-side reservoir 5 through the passage 37 of the intermediate wall 16. The hydraulic stator path 14 is not pressurized, and thus the reservoir control valve 17 is not actuated via the pressure line 30. The reservoir control valve 17 is held in its normal position by the spring 38, and thus the through-opening 19 is closed. As a result, the liquid level 36 in the machine-side reservoir 5 rises, and the liquid level in the transmission-side reservoir 6 drops compared to this machine-side reservoir 5. The high-speed mode can advantageously be applied to high-speed operation of the vehicle, i.e., high rotational speeds of the rotor 10 and the rotating components of the transmission 3.

[0028] FIG. 4 shows a second exemplary embodiment of the electric drive device in a schematic diagram similar to the first embodiment. Similar parts are denoted by the same reference numerals. Furthermore, the electric drive device according to the second embodiment is similar with respect to the housing 1, the electromechanical machine 2, the transmission 3 and the reservoir 4, and these will not be described in detail again. Refer to the above description.

[0029] The hydraulic circuit 7 of the second embodiment includes a pump 24 which is a bidirectional pump 24. Further, the mode control valve 12 is hydraulically actuated, and depending on the pumping direction of the bidirectional pump 24, the mode control valve 12 operates between a low speed mode and a high speed mode. A fluid supply line 20 that hydraulically connects the reservoir 4 to the bidirectional pump 24 is divided into two branches. The first branch 22 is connected to the first suction side inlet 23 of the pump 24, and the second branch 26 is connected to the second suction side inlet 27 of the pump 24. Depending on the speed mode, only one of the first suction side inlet 23 and the second suction side inlet 27 can actually form the suction side of the pump 24, and it is obvious that the other of each must be the pressure outlet of the pump 24. The first suction side inlet 23 is applied in the high speed mode, and the second suction side inlet 27 is applied in the low speed mode. The two branches 22, 26 rejoin at a junction point 28 downstream of the pump 24. The two branches 22, 26 are provided with a check valve device 29 having two check valves in each of the two branches 22, 26. Each of the first suction side inlet 23 and the second suction side inlet 27 is located between each of the two check valves respectively, and the check valve device 29 is adapted to allow flow through each of the two branches 22, 26 only in the direction from the reservoir 4 to the junction point 28. The mode control valve 12 is hydraulically actuated in this embodiment via a hydraulic line 30 connected to the first branch 22. Also, the reservoir control valve 17 is hydraulically actuated via the hydraulic line 30 connected to the first branch 22. The hydraulic stator path 14 connects the mode control valve 12 to a part of the electric machine 2 to supply fluid to the stator 9, and the hydraulic transmission path 15 connects the mode control valve 12 to a part of the transmission 3. The bidirectional pump 24 is driven by an electric motor 34. A suction filter 25 is arranged upstream of the pump 24, and downstream of the pump 24, the fluid can be cooled by a heat exchanger 35.

[0030] Next, the high-speed mode will be described with reference to FIG. 5. FIG. 5 shows the electric drive device of FIG. 4 with the hydraulic circuit 7 in the high-speed mode. The mode control valve 12 directs the fluid flow from the pump 24 to the hydraulic transmission path 15 that actively supplies lubricating fluid to the transmission 3. The branch conduit 8 of the hydraulic transmission path 15 also supplies fluid to the inner diameter portion 18 of the drive shaft 11 of the electromechanical machine 2 for cooling. The mode control valve 12 does not operate in the high-speed mode and is held in its normal position by the biasing spring 32. The check valve device 29 establishes the fluid flow in the high-speed mode from the first branch 22 to the first suction side inlet 23, further through the pump 24 to the second branch 26, and further to the junction point 28. The hydraulic line 30 connected to the first branch 22 is not pressurized by the pump 24 because the first branch 22 forms the suction side of the pump 24. Also, the reservoir control valve 17 is not actuated but is biased towards its normal position by the spring 38, and thus the through opening 19 in the inner wall 16 is closed.

[0031] By reversing the pumping direction of the bidirectional pump 24, the hydraulic circuit 7 is changed to the low-speed mode as shown in FIG. 6. The downstream pressure in the first branch 22 is biased towards its closed position by the check valve spring 39, which is adapted to accumulate pressure in the pressure line 30 while keeping the check valve closed at the moment the pumping direction is reversed. By pressurizing the first branch 22, both the mode control valve 12 and the reservoir control valve 17 are actuated to their respective operating positions via the pressure line 30 against the biasing forces of the springs 32, 38. The reservoir control valve 17 opens the through opening 19, and the mode control valve 12 directs the fluid flow to the hydraulic stator path 14. Then, the check valve device 29 having the check valve spring 39 can also be opened, and the check valve device 29 establishes the fluid flow in the low-speed mode from the second branch 26 to the second suction side inlet 27, further through the pump 24 to the first branch 22, and further to the junction point 28.

[0032] The illustrated parts and features of all exemplary embodiments of the electric drive device are schematic representations and may deviate from the technical drawing standards. Regarding the functions and technical details of the components and features, the description takes precedence over the drawings.

Explanation of Reference Numerals

[0033] 1 Housing 2 Electromechanism 3 Transmission 4 Reservoir 5 Motor-side Reservoir 6 Transmission-side Reservoir 7 Hydraulic Circuit 8 Branch Conduit 9 Stator 10 Rotor 11 Drive Shaft 12 Mode Control Valve 14 Hydraulic Stator Path 15 Hydraulic Transmission Path 16 Intermediate Wall 17 Reservoir Control Valve 18 Inner Diameter Portion of the Rotor Shaft 19 Through Opening 20 Fluid Supply Line 21 Radial Bore 22 First Branch 23 First Suction-side Inlet 24 Pump 25 Filter 26 Second Branch 27 Second Suction-side Inlet 28 Junction Point 29 Check Valve Device 30 Hydraulic Line 31 Stator End Coil 32 Spring 33 Spray Nozzle 34 Electric Motor 35 Heat Exchanger 36 Liquid Level 37 Passage 38 Spring 39 Check Valve Spring A Axis of Rotation F Arrow

Claims

1. An electric drive device for a vehicle, comprising: a housing (1); an electric machine (2) including a stator (9) connected to the housing (1) and including a stator end winding (31), a rotor (10) rotatable relative to the stator (9), and a drive shaft (11) connected to the rotor (10) and rotatably supported in the housing (1) about a rotation axis (A); a transmission (3) for transmitting the rotational movement from the drive shaft (11) to drive the drive line of the vehicle; a hydraulic circuit (7) for circulating a fluid, the hydraulic circuit (7) comprising a pump (24) hydraulically connected to a reservoir (4), a mode control valve (12) hydraulically connected to the pump (24), a hydraulic stator path (14) connecting the mode control valve (12) to a part of the electric machine (2) to supply the fluid to the stator (9), and a hydraulic transmission path (15) connecting the mode control valve (12) to a part of the transmission (3); characterized in that the mode control valve (12) is controllable to two positions such that in a low speed mode it assumes an operating position and directs the fluid flow from the pump (24) to the hydraulic stator path (14), whereby the fluid is supplied to the stator end winding (31) of the electric machine (2) via the hydraulic stator path (14), and in a high speed mode it assumes a normal position and directs the fluid flow from the pump (24) to the hydraulic transmission path (15), whereby the fluid is supplied to the transmission (3) via the hydraulic transmission path (15); the housing (1) includes an intermediate wall (16) separating the reservoir (4) into a motor-side reservoir (5) and a transmission-side reservoir (6), and a reservoir control valve (17) is arranged in a through-opening (19) of the intermediate wall (16) to selectively open or close the through-opening (19); electric drive device.

2. The electric drive device according to claim 1, characterized in that the reservoir control valve (17) is controllable such that the through-opening (19) is opened in the low speed mode and closed in the high speed mode.

3. In the low-speed mode, fluid is passively supplied to the transmission (3) from the transmission-side reservoir (6), and the liquid level in the transmission-side reservoir in the low-speed mode is higher than that in the high-speed mode. The electric drive device according to claim 1 or 2.

4. The hydraulic transmission path (15) includes a branch conduit (8) leading to the inner diameter portion (18) of the drive shaft (11). The electric drive device according to any one of claims 1 to 3.

5. The drive shaft (11) includes a radial bore (21) connecting the inner diameter portion (18) to the rotor (10) in order to supply fluid to the electromechanical machine (2) in the high-speed mode. The electric drive device according to claim 4.

6. The mode control valve (12) is a three-port two-position valve that is in the normal position in the high-speed mode and in the operating position in the low-speed mode. The electric drive device according to any one of claims 1 to 5.

7. The reservoir control valve (17) is a two-port two-position valve that is in the normal position in the high-speed mode and in the operating position in the low-speed mode. The electric drive device according to any one of claims 1 to 6.

8. The mode control valve (12) is actuated electromagnetically and / or The reservoir control valve (17) is hydraulically actuated via a hydraulic line connected to the hydraulic stator path (14). The electric drive device according to any one of claims 1 to 7.

9. The mode control valve (12) is hydraulically actuated, the pump (24) is a bidirectional pump, and the mode control valve is actuated according to the pumping direction of the pump. The electric drive device according to claim 6 or 7.

10. The fluid supply line (20) that hydraulically connects the reservoir (4) to the pump (24) is divided into two branches. The first branch (22) is connected to the first suction-side inlet (23) of the pump in the high-speed mode, and the second branch (26) is connected to the second suction-side inlet (27) of the pump in the low-speed mode. The two branches rejoin at a junction point (28) downstream of the pump. The electric drive device according to claim 9.

11. In the high-speed mode, the first branch (22) and the second branch (26) establish a fluid flow from the first branch (22) to the first suction-side inlet (23), then through the pump (24) to the second branch (26), and further to the junction point (28). In the low-speed mode, a check valve device (29) is provided to establish a fluid flow from the second branch (26) to the second suction-side inlet (27), then through the pump (24) to the first branch (22), and further to the junction point (28). The electric drive device according to claim 10.

12. The check valve device (29) includes two check valves for each of the first branch (22) and the second branch (26). Each of the first suction-side inlet (23) and the second suction-side inlet (27) is located between the two check valves respectively. The check valve device is adapted to allow flow through each of the two branches only in the direction from the reservoir (4) towards the junction point (28). The electric drive device according to claim 11.

13. The mode control valve (12) is hydraulically actuated via a hydraulic line (30) connected to the first branch (22). The electric drive device according to any one of claims 10 to 12.

14. The reservoir control valve (17) is hydraulically actuated via a hydraulic line (30) connected to the first branch (22). The electric drive device according to any one of claims 10 to 13.

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