Electric drive arrangement for a vehicle

Abstract

An electric drive arrangement for a vehicle, 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 for transmitting rotational motion from the rotor shaft to drive a drive train of the vehicle; a hydraulic circuit for circulating fluid to cool and lubricate the electric machine and the transmission.

Description

Technical Field

[0001] The present invention relates to an electric drive arrangement for a vehicle, comprising: a housing; an electric motor having a stator connected to the housing and a rotor having a rotor shaft rotatably supported in the housing; a transmission for transmitting rotational motion from the rotor shaft to drive the vehicle's driveline (sometimes referred to as a transmission system); and a hydraulic circuit for circulating fluid to cool and lubricate the electric motor and the transmission. Background Technology

[0002] A vehicle drive device is known from US2019 / 0229582A1, comprising: a lubrication path including a first oil pump for pumping oil stored in a housing upwards and supplying oil to a power transmission mechanism for lubrication of the power transmission mechanism; and a cooling path separate from the lubrication circuit and configured for a rotating motor, the cooling path including a second oil pump for pumping oil stored in a housing upwards and specifically supplying oil to the rotating motor for cooling the rotating motor, the second oil pump being an electric oil pump, and the cooling path being configured with an oil cooler for cooling the oil to be supplied to the rotating motor.

[0003] A method for dynamically monitoring the temperature of a fluid at a heat-generating device is known from US2016 / 0178548 A1. The method includes using a temperature sensor to monitor the temperature of a fluid held in a fluid reservoir. A first fluid flow rate and a second fluid flow rate are determined. A third fluid flow rate and a temperature drop of the fluid across a heat exchanger in the active coolant loop are determined based on the fluid temperature and the third fluid flow rate through the active coolant loop. The fluid temperature supplied to the motor through the active coolant loop 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 reservoir and the temperature of the fluid supplied to the motor through the active coolant loop.

[0004] US2018 / 241288A1 discloses a cooling structure for a rotating electric machine, in which a cooling medium is supplied by a pump to the stator and rotor of the rotating electric machine to cool the stator and rotor. The cooling structure includes: a first passage that supplies the cooling medium from the pump to the stator; a second passage that supplies the cooling medium from the pump to the rotor; and a valve that regulates the flow rate of the cooling medium in the first passage and the flow rate of the cooling medium in the second passage, wherein the cooling state of the stator and the cooling state of the rotor are controlled by the valve.

[0005] EP 3517335 A1 discloses an electric vehicle including a power control unit, a drive motor, a first cooling passage equipped with a first pump, and a second cooling passage equipped with a second pump. The first pump causes a first coolant cooled in a first heat exchanger to flow sequentially through the power control unit and a second heat exchanger and return to the first heat exchanger. The second pump causes a second coolant cooled by the first coolant in the second heat exchanger to flow through the drive motor and return to the second heat exchanger. The second pump starts or stops the circulation of the second coolant, or increases or decreases the circulation volume of the second coolant, based on one or both of the temperature of the power control unit and the temperature of the first coolant.

[0006] Electric motors and transmissions used in vehicles have varying cooling and lubrication requirements depending on operating conditions. Motor performance is thermally limited during operation. Inherent losses can occur in the copper, iron, and magnets of the motor, where material properties limit the temperature of the corresponding components and structures. Efficient cooling is essential to achieve sufficient torque performance. Passive splash lubrication in the transmission leads to churning losses at high speeds. The combination of cooling and lubrication for both the motor and transmission represents a trade-off in efficiency. Summary of the Invention

[0007] Therefore, the objective is to propose an electric drive system for vehicles, which includes a hydraulic circuit for circulating fluid to effectively cool and lubricate the motor and transmission.

[0008] This objective is achieved by an electric drive arrangement for a vehicle, comprising:

[0009] -case;

[0010] - An electric motor having a stator connected to a housing and a rotor having a rotor shaft rotatably supported in the housing;

[0011] - A transmission device for transmitting rotational motion from the rotor shaft to drive the vehicle's drive system;

[0012] - A hydraulic circuit used to circulate fluid for cooling and lubrication of the motor and transmission, the hydraulic circuit comprising:

[0013] A bidirectional pump hydraulically connected to the oil sump (sometimes called oil pan) of the housing on the suction side, a pump-actuated switching valve hydraulically connected to the bidirectional pump, a first hydraulic path connecting the switching valve to the cooling nozzle of the motor, a second hydraulic path connecting the switching valve to a part of the transmission, and a heat exchanger for cooling the fluid pumped by the bidirectional pump through the switching valve.

[0014] When the bidirectional pump is running in the first rotational direction, the switching valve is moved to the first position, so that fluid is pumped through the heat exchanger to the first hydraulic path for cooling the motor. When the bidirectional pump is running in the second rotational direction, the switching valve is moved to the second position, so that fluid is pumped through the heat exchanger to the second hydraulic path for cooling and / or lubricating the transmission.

[0015] The advantage of the electrically driven arrangement is that the two rotational directions of the bidirectional pump provide two modes of the hydraulic circuit, allowing for optimized cooling and lubrication of the motor and transmission by switching between the first and second rotational directions, depending on actual cooling and lubrication requirements. The second rotational direction of the bidirectional pump is advantageously suited for high-speed vehicle operation, whereby the high rotational speeds of the rotor and transmission components are supplied with fluid for cooling and lubrication. During high-speed operation, the motor torque requirement is lower, thus eliminating the need for motor cooling via cooling nozzles.

[0016] The first rotational direction of the bidirectional pump is advantageously suited for low-speed vehicle operation, and consequently, for the lower rotational speeds of the rotor and transmission components. However, high torque requirements are common at low speeds, and high current leads to copper losses. Therefore, the fluid supplied to the cooling nozzles can advantageously cool the stator end windings of the motor, thus reducing losses. When the bidirectional pump operates in the second rotational direction, high-pressure jet cooling of the winding heads is feasible, and the transmission lubrication does not require an active fluid supply. Passive splash lubrication of the transmission is effective under low-speed conditions because churning losses are lower due to the low rotational speed.

[0017] The fluid circulating in the hydraulic circuit is a cooling and lubricating fluid, such as oil. The oil reservoir, also known as a storage tank, is arranged to collect the fluid that drips from the motor and transmission due to gravity.

[0018] According to one embodiment, the switching valve has a first inlet connected to a first pressure side of a bidirectional pump and a second inlet connected to a second pressure side of the bidirectional pump. The switching valve is actuated to a first position by pressurizing the first inlet and to a second position by pressurizing the second inlet. The switching valve may have a first heat exchanger outlet hydraulically connected to a heat exchanger and a second heat exchanger outlet also hydraulically connected to a heat exchanger, wherein when the switching valve is in the first position, fluid flows from the first inlet to the heat exchanger, and when the switching valve is in the second position, fluid flows from the second inlet to the heat exchanger. The switching valve may also have a third inlet hydraulically connected to the heat exchanger, a first outlet to a first hydraulic path, and a second outlet to a second hydraulic path, wherein when the switching valve is in the first position, fluid flows from the heat exchanger to the first outlet, and when the switching valve is in the second position, fluid flows from the heat exchanger to the second outlet.

[0019] According to another embodiment, when the bidirectional pump operates in the first rotational direction, the first pressure side is pressurized to a first pressure level to supply fluid to the cooling nozzles for cooling the stator end windings, and when the bidirectional pump operates in the second rotational direction, the second pressure side is pressurized to a second pressure level to supply fluid for actively cooling the rotor and actively lubricating the drive mechanism. The first pressure level may be higher than the second pressure level.

[0020] According to another embodiment, the second hydraulic path includes a branch conduit leading to the inner diameter of the drive shaft. The motor can be supplied with fluid from the second hydraulic path via a radial bore in the drive shaft that connects the inner diameter to the rotor.

[0021] According to another embodiment, the housing includes an intermediate wall that separates the oil reservoir into a motor-side reservoir and a transmission-side reservoir, wherein when the bidirectional pump operates in a first rotational direction, the suction side is hydraulically connected to the motor-side reservoir, and when the bidirectional pump operates in a second rotational direction, the suction side is hydraulically connected to the transmission-side reservoir. The motor-side reservoir and the transmission-side reservoir can be hydraulically connected via a through opening in the intermediate wall. A suction filter may be arranged between the oil reservoir and the bidirectional pump, or between each of the motor-side reservoir and the transmission-side reservoir and the bidirectional pump. A check valve may be arranged between the oil reservoir and each of the first and second pressure sides of the bidirectional pump to disconnect a corresponding one of the first and second pressure sides from the corresponding suction side. Attached Figure Description

[0022] The following will illustrate exemplary embodiments and further advantages of an electric drive arrangement for a vehicle with reference to the accompanying drawings, wherein:

[0023] Figure 1 An exemplary embodiment of the electric drive arrangement is illustrated in schematic diagram;

[0024] Figure 2 A detailed schematic diagram is shown. Figure 1 The switching valve of the embodiment illustrates the operation of the bidirectional pump in the second rotation direction;

[0025] Figure 3 A detailed schematic diagram is shown. Figure 1 The switching valve of the embodiment illustrates the operation of the bidirectional pump in the second rotation direction;

[0026] Figure 4 Another exemplary embodiment of the electrically driven arrangement is illustrated in schematic diagram. Detailed Implementation

[0027] exist Figure 1The image depicts an electric drive arrangement for a vehicle, wherein the housing 1, motor 2, transmission 3, and oil reservoir 4 are shown schematically in a longitudinal section along the axis of rotation A of the rotor 10 of the motor 2. A hydraulic circuit 7 for circulating fluid to cool and lubricate the motor 2 and transmission 3 is also depicted schematically. Figure 2 Detailed schematic diagrams are shown in the middle. Figure 1 The switching valve 12 of the hydraulic circuit 7 is set in the second position 26. Figure 3 middle, Figure 1 The switching valve 12 of the hydraulic circuit 7 is shown in its first position 22. Figure 1 , Figure 2 and Figure 3 They will be described together.

[0028] The motor 2 has a stator 9 connected to the housing 1 and including stator end windings 31, and a rotor 10 rotatable relative to the stator 9. A drive shaft 11 is connected to the rotor 10 and rotatably supported in the housing 1 about a rotation axis A. A transmission 3, not depicted, is adapted to transmit rotational motion from the drive shaft 11 to drive a vehicle drive system. The transmission 3 may include, for example, a reduction gear, a differential drive, and a clutch (not shown). Fluid from the hydraulic circuit 7 is collected in an oil reservoir 4 formed in the lower portion of the housing 1. A bidirectional pump 24 is hydraulically connected to the oil reservoir 4 on the suction side via a fluid supply line 20. A suction filter 25 is arranged between the oil reservoir 4 and the suction side of the bidirectional pump 24 for filtering the fluid. The bidirectional pump 24 is also hydraulically connected to a pump-actuated switching valve 12. A first hydraulic path 14 connects the switching valve 12 to a cooling nozzle 33 of the motor 2, and a second hydraulic path 15 connects the switching valve 12 to a portion of the transmission 3. The heat exchanger 35 is configured to cool the fluid pumped by the bidirectional pump 24 through the switching valve 12. When the bidirectional pump 24 is operating in the first rotational direction, the switching valve 12 is moved to the first position 22, as... Figure 3 As shown, fluid is thus pumped through heat exchanger 35 to the first hydraulic path 14 for cooling motor 2. When the bidirectional pump 24 operates in the second rotational direction, switching valve 12 is moved to the second position 26, as... Figure 2 As shown, fluid is thus pumped through heat exchanger 35 to second hydraulic path 15 for cooling and / or lubricating transmission 3.

[0029] According to an exemplary embodiment, the switching valve 12 may have a first inlet 38 connected to a first pressure side 23 of the bidirectional pump 24 and a second inlet 39 connected to a second pressure side 27 of the bidirectional pump 24. The corresponding first pressure side 23 and second pressure side 27 depend on the rotational direction of the bidirectional pump 24. When the bidirectional pump 24 operates in the first rotational direction, the first pressure side 23 is pressurized, meaning the second pressure side 27 becomes the suction side of the bidirectional pump 24. When the bidirectional pump 24 operates in the second rotational direction, the second pressure side 27 is pressurized, and the first pressure side 23 becomes the suction side of the bidirectional pump 24. A check valve 29 between each of the first pressure side 23 and the second pressure side 27 and the fluid supply line 20 prevents backflow toward the oil reservoir 4. The switching valve 12 includes a valve housing 30 surrounding a gap 32 within which a valve core 17 is actuated to a first position 22 by pressurizing the first inlet 38 and to a second position 26 by pressurizing the second inlet 39. The switching valve 12 has a first heat exchanger outlet 41 hydraulically connected to the heat exchanger 35 and a second heat exchanger outlet 42 also hydraulically connected to the heat exchanger 35. When the switching valve 12 is in the first position, fluid flows from the first inlet 38 to the heat exchanger 35, and when the switching valve 12 is in the second position, fluid flows from the second inlet 39 to the heat exchanger 35. The switching valve 12 has a third inlet 40 hydraulically connected to the heat exchanger 35, a first outlet 43 to a first hydraulic path 14, and a second outlet 44 to a second hydraulic path 15. When the valve spool 17 of the switching 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 switching valve 12 is in the second position 26, fluid flows from the heat exchanger 35 to the second outlet 44. The hydraulically connected lines are shown with points indicating joints. Cross lines without joint points are hydraulically separated. Figure 3 The first position 22 and Figure 2 The second position 26 in the diagram, as indicated by arrow F, shows the fluid flow through switching valve 12.

[0030] When the bidirectional pump 24 operates in the first rotational direction, the first pressure side 23 is pressurized to a first pressure level to supply fluid to the cooling nozzle 33 for spraying cooling of the stator end winding 31 of the stator 9. The cooling nozzle 33 sprays fluid at high pressure toward the stator end winding 31, from which the fluid flows back to the oil reservoir 4, indicated by the dashed line 36. Arrow F clarifies the fluid flow. The second hydraulic path 15 is not pressurized, and no fluid is actively delivered to the transmission 3, which is splash-lubricated from the oil reservoir 4. The bidirectional pump 24 is advantageously suited for low-speed operation of the vehicle, and accordingly, the lower rotational speed of the rotating components of the rotor 10 and the transmission 3 operates in the first rotational direction.

[0031] When the bidirectional pump 24 operates in the second rotational direction, 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 includes a branch conduit 8 leading to the inner diameter 18 of the drive shaft 11. The motor 2 is supplied with fluid from the second hydraulic path 15 via a radial bore 21 of the drive shaft 11 that connects the inner diameter 18 to the rotor 10. The fluid travels centrifugally along the rotor 10 toward the stator 9 and flows back into the oil reservoir 4 due to gravity, as indicated by arrow F. The fluid travels from the transmission 3 back into the oil reservoir 4. The bidirectional pump 24 is advantageously suited for the high-speed operation of the vehicle and, consequently, the high rotational speed of the rotating components of the rotor 10 and the transmission 3 in the second rotational direction.

[0032] exist Figure 4 A second exemplary embodiment of the electric drive arrangement is shown in the same schematic diagram as the first embodiment. Identical components are indicated by the same reference numerals. The electric drive device according to the second embodiment is further identical in terms of the housing 1, motor 2, transmission device 3, and reservoir 4, which will not be described in detail again. Refer to the description above. Since the switching valve 12 of the second exemplary embodiment can be the same as the switching valve 12 of the first embodiment, further reference is made... Figure 2 and Figure 3 As mentioned above.

[0033] 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, which are connected via a through opening 19 in the intermediate wall 16. The motor-side reservoir 5 and the transmission-side reservoir 6 are each hydraulically connected to a bidirectional pump 24 via two separate fluid supply lines 20, each connected to a feasible suction side of the bidirectional pump 24 depending on the direction of rotation. The two fluid supply lines 20 include one of two suction filters 25 for filtering the fluid.

[0034] When the bidirectional pump 24 operates in the first rotational direction, the first pressure side 23 is pressurized, and the motor-side reservoir 5 is hydraulically connected to the suction side of the bidirectional pump 24. As the switching valve 12 is moved to the first position 22, fluid is supplied via the first hydraulic path 14 to the cooling nozzle 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 also allows fluid dripping from the transmission 3 to flow into the machine-side reservoir 5. However, due to the through opening 19, the liquid level 36 in the machine-side reservoir 5 is balanced with the liquid level in the transmission-side reservoir 6.

[0035] When the bidirectional pump 24 operates in the second rotational direction, the second pressure side 27 is pressurized, and the transmission-side reservoir 6 is hydraulically connected to the suction side of the bidirectional pump 24. As the switching valve 12 is moved to 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 small portion of the fluid travels from the transmission 3 back to the machine-side reservoir 5 through passage 37 in the intermediate wall 16. 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 bidirectional pump 24, the liquid level in the transmission-side reservoir 6 can advantageously be reduced. To achieve this, the flow rate through the through-opening 19, as illustrated by arrow F, can be adjusted by selecting an appropriate diameter for the through-opening 19. The diameter of the through-opening 19 results in a higher liquid level 36 in the machine-side reservoir 5 compared to that in the transmission-side reservoir 6, advantageously maintaining lower churning losses during high-speed vehicle operation.

[0036] Reference number list

[0037] 1. Shell

[0038] 2 motors

[0039] 3. Transmission device

[0040] 4 oil storage tanks

[0041] 5 motor-side storage

[0042] 6. Transmission device side storage

[0043] 7 Hydraulic Circuit

[0044] 8-branch catheter

[0045] 9 stators

[0046] 10 rotors

[0047] 11 drive shafts

[0048] 12 switching valves

[0049] 14 First Hydraulic Path

[0050] 15 Second hydraulic path

[0051] 16 intermediate walls

[0052] 17 cores

[0053] 18 Inner diameter of rotor shaft

[0054] 19 through openings

[0055] 20 fluid supply lines

[0056] 21 radial holes

[0057] 22 First Position

[0058] 23 First suction side

[0059] 24 bidirectional pump

[0060] 25 filters

[0061] 26 Second position

[0062] 27 Second suction side

[0063] 28 connector

[0064] 29 Check Valve

[0065] 30 valve housing

[0066] 31 Stator end winding

[0067] 32 gaps

[0068] 33 Injection Nozzle

[0069] 34 electric motors

[0070] 35 heat exchanger

[0071] 36 liquid level

[0072] 37 channels

[0073] 38 First Entrance

[0074] 39 Second Entrance

[0075] 40 Third Entrance

[0076] 41 First heat exchanger outlet

[0077] 42 Second heat exchanger outlet

[0078] 43 First Exit

[0079] 44 Second Exit

[0080] A axis of rotation

[0081] F arrow

Claims

1. An electric drive arrangement structure for a vehicle, comprising: Shell (1); The motor (2) has a stator (9) connected to the housing (1) and a rotor (10) having a rotor shaft (11) rotatably supported in the housing (1); Transmission device (3) for transmitting rotational motion from the rotor shaft (11) to drive the drive system of the vehicle; A hydraulic circuit (7) for circulating fluid to cool and lubricate the motor (2) and the transmission (3) includes a bidirectional pump (24) hydraulically connected to an oil reservoir (4) of the housing (1) on the suction side, a pump-actuated switching valve (12) hydraulically connected to the bidirectional pump (24), a first hydraulic path (14) connecting the switching valve (12) to a cooling nozzle (33) of the motor (2), a second hydraulic path (15) connecting the switching valve (12) to a portion of the transmission (3), and a heat exchanger (35) for cooling the fluid pumped by the bidirectional pump (24) through the switching valve (12). When the bidirectional pump (24) is running in the first rotational direction, the switching valve (12) is moved to the first position (22), so that fluid is pumped through the heat exchanger (35) to the first hydraulic path (14) for cooling the motor (2), and when the bidirectional pump (24) is running in the second rotational direction, the switching valve (12) is moved to the second position (26), so that fluid is pumped through the heat exchanger (35) to the second hydraulic path (15) for cooling and / or lubricating the transmission device (3).

2. The electric drive arrangement structure according to claim 1, wherein, The switching valve (12) has a first inlet (38) connected to a first pressure side (23) of the bidirectional pump (24) and a second inlet (39) connected to a second pressure side (27) of the bidirectional pump (24).

3. The electric drive arrangement structure according to claim 2, wherein, The switching valve (12) is actuated to the first position (22) by pressurizing the first inlet (38) and to the second position (26) by pressurizing the second inlet (39).

4. The electric drive arrangement structure according to any one of claims 2 or 3, wherein, The switching 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), wherein when the switching valve (12) is in the first position, fluid flows from the first inlet (38) to the heat exchanger (35), and when the switching valve (12) is in the second position, fluid flows from the second inlet (39) to the heat exchanger (35).

5. The electric drive arrangement structure according to any one of claims 1 to 3, wherein, The switching 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), wherein when the switching valve (12) is in the first position, fluid flows from the heat exchanger (35) to the first outlet (43), and when the switching valve (12) is in the second position, fluid flows from the heat exchanger (35) to the second outlet (44).

6. The electric drive arrangement structure according to claim 2 or 3, wherein, When the bidirectional pump (24) is running in the first rotational direction, the first pressure side (23) is pressurized to a first pressure level to supply fluid to the cooling nozzle (33) for cooling the stator end winding (31) of the stator (9).

7. The electric drive arrangement structure according to claim 2 or 3, wherein, When the bidirectional pump (24) is running in the second rotational direction, the second pressure side (27) is pressurized to a second pressure level to supply fluid for actively cooling the rotor (10) and actively lubricating the transmission.

8. The electric drive arrangement structure according to claim 7, wherein, When the bidirectional pump (24) is running in the first rotational direction, the first pressure side (23) is pressurized to a first pressure level to supply fluid to the cooling nozzle (33) for cooling the stator end winding (31) of the stator (9), wherein the first pressure level is higher than the second pressure level.

9. The electric drive arrangement structure according to any one of claims 1 to 3, wherein, The second hydraulic path (15) includes a branch conduit (8) leading to the inner diameter (18) of the rotor shaft (11).

10. The electric drive arrangement structure according to claim 9, wherein, The rotor shaft (11) includes a radial bore (21) that connects the inner diameter (18) to the rotor (10) for supplying fluid to the motor (2) from the second hydraulic path (15) in high-speed mode.

11. The electric drive arrangement structure according to any one of claims 1 to 3, wherein, The housing (1) includes an intermediate wall (16) that separates the oil reservoir (4) into a motor-side reservoir (5) and a transmission-side reservoir (6), wherein the suction side is hydraulically connected to the motor-side reservoir (5) when the bidirectional pump (24) is running in a first rotational direction, and the suction side is hydraulically connected to the transmission-side reservoir (6) when the bidirectional pump (24) is running in a second rotational direction.

12. The electric drive arrangement structure according to claim 11, wherein, The motor-side reservoir (5) and the transmission-side reservoir (6) are hydraulically connected via a through opening (19) in the intermediate wall (16).

13. The electric drive arrangement structure according to any one of claims 1 to 3, wherein, A suction filter (25) is arranged between the oil storage tank (4) and the bidirectional pump (24).

14. The electric drive arrangement structure according to any one of claims 1 to 3, wherein, A check valve (29) is arranged between the oil storage tank (4) and the bidirectional pump (24).

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