Electric drive system for independent wheel drive

Abstract

The present application relates to an electric drive system for independent wheel drive. The drive unit includes a housing, a main shaft, an output shaft, an electric motor, a first planetary gear set, and a second planetary gear set. The main shaft is rotatably disposed in the housing and cooperatively defines an axis of rotation with the housing. The output shaft is at least partially disposed in the housing and rotatable about the axis. The electric motor is disposed in the housing and has a rotor centered about and rotatable about the axis. The first planetary gear set is centered about the axis and provides a first reduction ratio between the rotor and the second planetary gear set. The second planetary gear set provides a second reduction ratio between the first planetary gear set and the output shaft.

Description

[0001] This application is a divisional application of Chinese patent application 201810358541.X, entitled "Electric Drive System for Independent Wheel Drive", filed on April 20, 2018. Technical Field

[0002] This application relates to an electric drive system for independent wheel drive. Background Technology

[0003] A hybrid internal combustion engine electric powertrain may include multiple electric motors combined with an internal combustion engine. A first or main electric motor may be used in series with the internal combustion engine or alternatively in parallel to power the front or rear wheels of the vehicle. An auxiliary drive system may be used to power wheels that do not receive power from the internal combustion engine. The auxiliary system may include a drive unit for each wheel, wherein each unit further includes an electric motor and a gear set disposed between the electric motor and the associated wheel. Known auxiliary drive units may have a finite operating cycle time period. It is desirable to provide an auxiliary electric drive system having drive units suitable for operation within the available space of the vehicle during the duration period. Attached Figure Description

[0004] Figure 1 This is a schematic plan view of an exemplary hybrid electric IC powertrain assisted by an exemplary compact electric drive.

[0005] Figure 2 yes Figure 1 A cross-sectional view of a compact electric drive.

[0006] Figure 3 yes Figure 2 An enlarged view of an exemplary right-side drive unit of an electric drive.

[0007] Figure 4 This is an illustration of an exemplary power flow. Detailed Implementation

[0008] Relative orientation and direction (by way of example, above, below, bottom, forward, backward, front, rear, back, outside, inside, inward, outward, lateral, left, right) are not intended to be limiting in this description, but are provided to facilitate the reader in describing at least one embodiment of the structure. Such exemplary orientation is from the perspective of a passenger seated facing the dashboard. In the accompanying drawings, the same reference numerals indicate the same parts in all the views.

[0009] The drive unit includes a housing, a main shaft, an output shaft, a motor, a first planetary gear set, and a second planetary gear set. The main shaft is rotatably disposed within the housing and cooperates with the housing to define an axis of rotation. The output shaft is at least partially disposed within the housing and is rotatable about the axis. The motor is disposed within the housing and has a rotor centered on and rotatable about the axis. The first planetary gear set is centered on the axis and provides a first reduction ratio between the rotor and the second planetary gear set. The second planetary gear set provides a second reduction ratio between the first planetary gear set and the output shaft.

[0010] The first planetary gear set may include a ring gear fixed to the rotor, a planet carrier fixed to the housing, and a sun gear fixed to the main shaft.

[0011] The electric motor may include a stator fixed to and disposed within a housing. The rotor may include a ring, a hub, and a flange. The ring may be radially disposed within the stator. The hub is rotatably disposed on a main shaft. The flange may extend radially between the hub and the ring and securely connect the hub and the ring. A ring gear may be fixed to the rotor ring. The ring gear, sun gear, and planet gears of the first planetary gear set may all be axially disposed between the rotor flange and the inner edge of the rotor ring.

[0012] The second planetary gear set may include a sun gear fixed to the main shaft, a ring gear fixed to the housing, and a planet carrier fixed to the output shaft.

[0013] The housing may be partially formed from the engine oil pan.

[0014] Engine oil can be used as a lubricant for gear sets.

[0015] The stator of the electric motor can be liquid-cooled.

[0016] The vehicle may include an internal combustion engine and a drive system. The internal combustion engine may have an engine oil pan. The drive system may include a first drive unit and a second drive unit, each drive unit being connected to drive wheels. Each drive unit may include a housing, a main shaft, an output shaft, an electric motor, a first planetary gear set, and a second planetary gear set. The housing may be connected to the engine oil pan. The main shaft is rotatably disposed within the housing. The housing may cooperatively define an axis of rotation. The output shaft may be at least partially disposed within the housing and rotatable about the axis. The electric motor may be disposed within the housing and may have a rotor centered on and rotatable about the axis. The first planetary gear set is centered on the axis and provides a first reduction ratio between the rotor and the second planetary gear set. The second planetary gear set provides a second reduction ratio between the first planetary gear set and the output shaft.

[0017] like Figure 1 As illustrated, the exemplary motor vehicle 10 may include a hybrid powertrain 12 assisted by a compact electric drive system 14.

[0018] An exemplary hybrid powertrain 12 may include an internal combustion engine 16, an electric motor 18 (i.e., an electric generator 18), a shift transmission 20, a drive shaft 21, an axle 22 including a differential, and a rear wheel 24 connected to the axle 22.

[0019] refer to Figure 2 The compact drive system 14 may include a right drive unit 26 and a left drive unit 28. Each drive unit 26, 28 is essentially a mirror image of the other drive unit. The right drive unit 26 is connected to the right front drive wheel 30 via a right front half-shaft 32. Similarly, the left drive unit 28 is connected to the left front drive wheel 34 via a right front half-shaft 36. Depending on a common half-shaft configuration, the right and left front half-shafts may each include an inner constant velocity joint and an outer constant velocity joint.

[0020] refer to Figure 3 The right drive unit 26 is described in more detail below. As mentioned above, the left drive unit 28 is essentially a mirror image of the right drive unit. Therefore, the description of the right drive unit 26 applies to the left drive unit 28.

[0021] The drive unit 26 includes a drive unit motor 38 (i.e., an electric generator 38) and may include a first reduction gear set 40 and a second reduction gear set 42. The motor 38 and the gear sets 40 and 42 are disposed within a right-side compact drive unit housing 44. The housing 44 includes an inner housing 46 and an outer housing 48. The inner housing 46, defining the inner portion of the housing 48, may be formed as part of the engine oil pan 50 of the internal combustion engine 16, such as... Figure 2 and 3 As described herein, it may be fixedly connected to the engine oil pan 50 in other ways. The right drive unit housing 48 may be fixed to the outside of the inner housing 46. The inner housing 46 and the housing 48 cooperate to protect and support the motor 38 and the gear sets 40, 42.

[0022] Gear sets 40 and 42 are disposed in the power flow path 52 between the motor 38 and the right output flange 54. The right output flange 54 is connected to the right half-shaft 32.

[0023] The intermediate wall 56 can be set between the motor 38 and the second reduction gear set 42.

[0024] The electric motor 38 includes a stator 58 and a rotor 60. The stator 58 is fixed and disposed within a housing 44. The stator 58 may be surrounded or contained within a liquid-cooled cooling sleeve 62. The cooling sleeve 62 may include coolant passages 64 for a liquid coolant. Electric motors with liquid-cooled cooling sleeves are known and commercially available. One company that sells liquid-cooled electric motors is WEG Electric Corporation.

[0025] The rotor 60 is rotatably mounted on the spindle 66. The spindle 66 and the housing 44 cooperate to define an axis of rotation 68 about which the spindle 66 and the rotor 60 rotate. Bearings (e.g., needle roller bearings 70) may be radially disposed between the spindle 66 and the rotor 60.

[0026] The rotor 60 may include a magnet retaining rotor ring 72 at the outer diameter of the rotor 60, a rotor hub 74 at the center of the rotor 60, and a rotor flange 76 disposed between the hub 74 and the ring 72 and connecting the hub and the ring. The ring 72 is radially disposed within the stator 58. The bearing 70 is radially disposed between the hub 74 and the main shaft 66.

[0027] A first reduction gear set 40 is disposed between the rotor 60 and the main shaft 66 and drivesly connects the rotor 60 and the main shaft 66. An exemplary gear set 40 illustrates one method of providing a reduction ratio between the rotor 60 and a second reduction gear set 42. The first reduction gear set 40 is a planetary gear set including a first ring gear 78, a plurality of first planetary gears 80 held by a first planet carrier 82, and a first sun gear 84. The ring gear 78 is fixed to the rotor ring 72 for movement therewith. As illustrated, the ring gear 78 is directly fixed to the ring 72, but alternatively, it is connected to the ring via an intermediate member (e.g., a flange 76). The sun gear 84 may be formed as part of the main shaft 66, or alternatively may be pressed onto or otherwise fixed to the shaft 66 for movement therewith. The planetary gears 82 are radially disposed between the ring gear 78 and the sun gear 84, wherein the teeth of the planetary gear 82 mesh with the teeth of each of the ring gear 78 and the sun gear 84. Each planetary gear 80 is rotatably mounted on a first planetary shaft 86. Planetary shaft 86 is fixed to planetary carrier 82. First planetary carrier 82 is fixed relative to housing 44. Planetary carrier 82 may be partially formed by inner housing 46. A second portion of planetary carrier 82 may be provided by first planetary carrier bracket 88 fixed to inner housing 46. First reduction gear set 40 is centered on axis 68, i.e., the diameters of ring gear 78, sun gear 84, and planetary shaft 86 are all centered on axis 68. First reduction gear set 40 is substantially entirely radially and axially arranged within rotor ring 72 on the inner side of flange 76, i.e., ring gear 78, sun gear 84, and planetary gear 80 are all axially arranged between rotor flange 76 and the inner edge 89 of rotor ring 72. This arrangement helps to allow for an axially compact power flow path 52 and drive unit 26.

[0028] A second reduction gear set 42 is disposed between the main shaft 66 and the output flange 54 and drivesly connects the main shaft 66 and the output flange 54. The second reduction gear set 42 is a planetary gear set including a second sun gear 90, a plurality of second planetary gears 92 held by a second planetary carrier 94, and a second ring gear 96. An exemplary sun gear 90 is fixed to the main shaft 66 for rotation therewith. The sun gear 90 is formed separately from and fixed to the main shaft, but alternatively, it is formed integrally with it. The second ring gear 96 is fixed to the housing 48 to prevent rotation of the ring gear 96. The planetary gears 92 are radially disposed between the sun gear 90 and the ring gear 96, wherein the teeth of the planetary gear 92 mesh with the teeth of each of the sun gear 90 and the ring gear 96. Each planetary gear 92 is rotatably mounted on a second planetary shaft 98. The planetary shaft 98 is fixed to the second planetary carrier 94. The planetary carrier 94 may include a web member (not shown) providing a rigid connection between the inner side of the planetary carrier 94 and the outer side of the planetary carrier. The planetary carrier can be fixed to its outer side to form a unit, for example, together with the splined output shaft 100, which is at least partially disposed in the housing 44. The flange 54 may have a splined hub that slides on the output shaft 100. The spline engagement of the flange 54 and the shaft 100 prevents relative rotation. A retaining nut 102 may be disposed on the threaded end of the shaft 100 to retain the flange on the shaft 100. The second reduction gear set 42 is centered on axis 68, i.e., the diameters of the ring gear 96, the sun gear 90, and the planetary shaft 98 are all centered on axis 68. The exemplary gear set 42 illustrates one method of providing a reduction ratio between the first planetary gear set 40 and the output shaft 100.

[0029] Multiple bearings (e.g., ball bearings) can be used to maintain all rotating parts of unit 26 (i.e., shaft 66 and the sun gears 84, 90 thereon), rotor 60, second planetary carrier 94, and flange 54 attached thereto, centered on rotation about axis 68. Such bearings may include an inner spindle support bearing 104, with an outer race disposed within a cavity of the inner housing 46. A first planetary carrier-rotor bearing 106 may be radially disposed between the first planetary carrier 82 and rotor hub 74. A rotor-intermediate wall bearing 108 may be radially disposed between rotor hub 74 and a first axially extending lip of intermediate wall 56. A second planetary carrier-intermediate wall bearing 110 may be radially disposed between a second axially extending lip of intermediate wall 56 and hub of second planetary carrier 94. A second planetary carrier support bearing 112 may be disposed between outer hub of housing 48 and bearing retainer of output shaft 100. An output seal 114 disposed outside bearing 112 may be in the form of a lip seal. The spindle support bearing 116 between the outer end of the spindle 66 and the inner hole on the outer side of the second planetary carrier 94 can be a needle roller bearing.

[0030] A motor rotary transformer 117, which can be used to control the motor 38, can be fixed to a first axially extending lip of the intermediate wall 56. The rotary transformer can be located radially outside the lip and bearing 108.

[0031] Coolant can be supplied to passage 64 through coolant inlet 118, which may be formed in inner housing 46. Coolant can exit passage 64 through coolant outlet 120, which may also be formed in inner housing 46. The coolant may be from the cooling system of the internal combustion engine. Alternatively, the coolant may be another fluid specifically used for cooling the electric motors of drive units 26 and 28.

[0032] Lubricant for lubricating the mating surfaces of gear teeth and bearings can be received through lubricant inlet 122. The lubricant can be routed through a lubrication circuit, which may include channels and orifices to guide the lubricant to desired areas. Gravity can be used to help guide the flow of the lubricant. The lubrication circuit can guide the lubricant to a lubricant reservoir 124 at the bottom of housing 44. An exemplary lubricant reservoir 124 is found located at the bottom of housing 48. Lubricant outlet 126 allows the lubricant to return to the lubricant pump. The lubricant can be engine oil. The use of engine oil is facilitated by using an oil pan 50 to form the inner housing 46. Using engine oil as a lubricant also allows an oil pump within engine 16 to supply lubricant to the drive units, thus avoiding the need for separate pumps and fluid distribution systems for drive units 26, 28. Alternatively, when transmission 20 is an automatic transmission equipped with a fluid pump, the lubricant can be transmission fluid supplied by connecting a pressure line (not shown) from transmission 20 to the lubricant inlet 122 of units 26, 28. Transmission fluid will return to transmission 20 via a connecting conduit between lubricant outlet 126 and transmission 20. Alternatively, compact drive system 14 may have a separate lubrication system with its own pump to lubricate drive units 26 and 28.

[0033] Refer again Figure 1 The power management system 128 may include an electronic control unit 130, an engine controller 132, a power electronics unit 134, and a vehicle battery 136. Although not shown, the power management system 128 may also include, for example, a high-voltage power bus of 300 volts DC, a low-voltage power bus of 12 volts DC, and an electronic communication bus. Electronic communication may alternatively be conducted wirelessly via, for example, Bluetooth technology.

[0034] The electronic control unit 130 may include a computing device, which includes a memory for storing data and commands, including system logic, and a processor for executing commands. The electronic control unit 130 may be programmed to operate each of the hybrid powertrain 12 and the compact drive system 14, and to coordinate the operation of the hybrid powertrain 12 and the compact drive system 14.

[0035] The vehicle battery 136 can be a high-voltage battery, such as 300-volt DC.

[0036] The power electronics unit 134 may include a first transformer to convert direct current (DC) power from the battery into three-phase alternating current (AC) power for use by the motor 38 of each of the drive units 26, 28 and the motor 18. The power electronics unit 134 may also include a second transformer to convert 300 volts DC power into 12 volts DC power. Alternatively, the power management system 128 may additionally include a low-voltage (e.g., 12-volt) battery. The power electronics unit 134 may respond to commands from the electronic control unit 130.

[0037] The engine controller 132 may include multiple actuators and sensors for managing airflow, fuel supply and engine ignition, and ultimately the torque and speed of the engine 16. Such actuators and sensors (e.g., throttle body, fuel injector, mass airflow sensor and crankshaft position sensor) are known.

[0038] In operation, the electronic control unit 130 can be programmed to actuate the compact drive system 14 to drive the front wheels 30, 34, regardless of whether the rear wheels 24 are driven. Actuation of the compact drive system 14 can also be coordinated with actuation of the powertrain 12 and drive of the rear wheels 24. An example of vehicle handling that can benefit from coordination between the electronic control unit 130 of the hybrid powertrain 12 and the compact drive system 14 is torque vectoring control in all-wheel drive operation mode. An example of vehicle handling that can be performed independently of the compact drive unit of the hybrid powertrain 12 (i.e., without a drive torque contribution from the hybrid powertrain 12) is parallel parking.

[0039] When one of the drive units 26 and 28 is invoked to provide drive torque, each drive unit responds in substantially the same manner. The description of the operation of the right drive unit 26 applies to the operation of the left drive unit 28.

[0040] As described above, the drive unit 26 can be continuously supplied with lubricating fluid and liquid coolant during operation of the vehicle 10. The rotational speed of the rotor 60 can depend on vehicle operating conditions including the speed of the vehicle 10 and the steering angle of the front wheels 30, 34. The rotor 60 can be driven rearward by the rotation of the wheels 30. Similarly, when the wheels 30 are not rotating, the rotor 60 does not rotate.

[0041] Commands from the electronic control unit 130 direct the power electronics unit to supply power to the motor 38. In response to the power input, torque is generated between the stator 58 and the rotor 60. When the torque overcomes the vehicle's resistance (including frictional resistance and vehicle inertia), the rotor 60 responds to the torque and begins to rotate if it has not yet rotated.

[0042] The torque from the electric motor 38 follows power flow path 52. The first ring gear 78 rotates together with the rotor 60 as a unit. The planetary gear 80 is driven by the first ring gear 78. The planetary gears mounted to the fixed planet carrier 82 act as idlers between the ring gear 78 and the first sun gear 84. The main shaft 66, fixed to the sun gear 84, rotates at the same speed as the sun gear 84. The rotational speed ω of the main shaft 66 is... MS The number of teeth N on the first ring gear 78 can be used as a basis. R1 The number of teeth N on the first sun gear 84 S1 The rotational speed ω of rotor 60 R The function is used to calculate. The resulting equation (where the negative sign indicates the change in the direction of rotation) is: (1) ω MS =-ω R *(N S1 / N R1 ).

[0043] Continuing along path 52, as the main shaft 66 rotates, the second sun gear 90 rotates at the same speed, thereby driving the second planetary gear 92. With the second ring gear 96 fixed to the housing 48 and the second planetary carrier 94 rotating freely, the planetary gear 92 rotates on the shaft 98 while simultaneously rotating around the axis 68 with the second planetary carrier 94. The rotational speed ω is equal to that of the output shaft 100. SS The rotational speed of the second planetary carrier 94 can be based on the number of teeth N on the second sun gear 90. S2 The number of teeth N on the second ring gear 96 R2 The rotational speed ω of the main shaft 66 MS The function is used to calculate. The resulting equation is: (2) ω SS =ω MS *(N S2 / (N S2 +N R2 )) Output shaft speed W relative to rotor speed ω R The value can be obtained by taking the principal axis velocity ω from equation (1). MS Substitute the value into equation 2 to determine: (3) ω SS = -ω R *(N S1 / N R1 )*(N S2 / (N S2 +N R2 )) refer to Figure 4The relationships between equations (1), (2), and (3) are illustrated in power flow illustration 138. Vertical axis 140 is used to indicate the number of teeth N on gears 84, 78, 90, and 96. S1 N R1 N S2 and N R2 The horizontal line is used to represent the relative rotational speed ω. R ω MS and ω SS The velocity of each of the non-rotating first planetary carrier 82 and the second ring gear 96 is shown as zero. The magnitude of the rotational speed increases with the distance of the arrow tip from the axis 140. The direction of the arrow indicates the relative direction of rotation. Figure 138 clearly illustrates the velocity ω. R First, the speed is reduced from 40 by the first gear set to ω. MS Its speed is further reduced to ω by the second gear set 42. SS Assuming that the effect of gear sets 40 and 42 on torque is the inverse of the effect of gear sets 40 and 42 on speed, the figure also clearly illustrates that gear sets 40 and 42 increase the torque at output shaft 100 relative to the torque at rotor 60.

[0044] As used in this article, the adverb "basically" refers to shapes, structures, measurements, quantities, times, etc., that may deviate from precise descriptions of geometry, distance, measurement, quantity, time, etc., due to defects in materials, processing, manufacturing, data transmission, computing speed, etc.

[0045] The contents of this disclosure have been described in an illustrative manner; it should be understood that the terminology used is intended to be descriptive rather than restrictive. In light of the foregoing teachings, many modifications and variations of this disclosure are possible, and this disclosure may be practiced in ways different from the specific descriptions.

Claims

1. A driving unit, comprising: case; An electric motor disposed in the housing has a rotor centered on an axis and capable of rotating relative to the housing about the axis; A main shaft is received in the rotor, the main shaft being rotatable relative to the rotor about the axis, wherein the rotor is rotatably disposed on the main shaft; An output shaft, which is at least partially disposed within the housing and is rotatable about the axis; A first planetary gear set, centered on the axis and radially disposed between the rotor and the main shaft, providing a first reduction ratio between the rotor and the main shaft, and comprising a first ring gear fixed to the rotor, a first planet carrier fixed to the housing, and a first sun gear fixed to the main shaft; and The second planetary gear set provides a second reduction ratio between the main shaft and the output shaft. The first planetary gear set and the second planetary gear set are disposed within the housing, wherein: The electric motor includes a stator fixed to the housing and disposed within the housing; The rotor includes: Rotor rings, which are radially disposed within the stator, A hub, which is rotatably mounted on the main shaft, and A rotor flange that extends radially between the hub and the rotor ring and securely connects the hub and the rotor ring; The rotor is radially supported on the first planetary gear set via the rotor ring and radially supported on the main shaft via the hub.

2. The drive unit according to claim 1, wherein the first ring gear is fixed to the rotor ring, and the first ring gear, the first sun gear, and the plurality of first planetary gears of the first planetary gear set are all axially disposed between the rotor flange and the inner edge of the rotor ring.

3. The drive unit according to claim 1, wherein the second planetary gear set includes a second sun gear fixed to the main shaft, a second ring gear fixed to the housing, and a second planet carrier fixed to the output shaft.

4. The drive unit according to claim 1, wherein the housing is partially formed by an engine oil pan.

5. The drive unit according to claim 4, wherein the lubricant used for the gear set is engine oil.

6. The drive unit according to claim 1, wherein the stator of the motor is liquid-cooled.

7. A driving unit, comprising: case; An electric motor disposed in the housing has a rotor centered on an axis and capable of rotating relative to the housing about the axis; A main shaft is received in the rotor, the main shaft being rotatable relative to the rotor about the axis, wherein the rotor is rotatably disposed on the main shaft; An output shaft, which is at least partially disposed within the housing and is rotatable about the axis; A first planetary gear set, which is radially disposed between the rotor and the main shaft with the axis as its center, and provides a first reduction ratio between the rotor and the main shaft; and The second planetary gear set provides a second reduction ratio between the main shaft and the output shaft, and includes a second sun gear fixed to the main shaft, a second ring gear fixed to the housing, and a second planet carrier fixed to the output shaft. The first planetary gear set and the second planetary gear set are disposed within the housing, wherein: The electric motor includes a stator fixed to the housing and disposed within the housing; The rotor includes: Rotor rings, which are radially disposed within the stator, A hub, which is rotatably mounted on the main shaft, and A rotor flange that extends radially between the hub and the rotor ring and securely connects the hub and the rotor ring; The rotor is radially supported on the first planetary gear set via the rotor ring and radially supported on the main shaft via the hub.

8. The drive unit according to claim 7, wherein the housing is partially formed by an engine oil pan.

9. The drive unit according to claim 8, wherein the lubricant for the gear set is engine oil.

10. The drive unit according to claim 7, wherein the stator of the motor is liquid-cooled.

11. A vehicle comprising: An internal combustion engine, which has an engine oil pan; A drive system including first and second drive units, each drive unit being connected to a drive wheel and each drive unit including: A housing that is connected to the engine oil pan; An electric motor disposed in the housing has a rotor centered on an axis and capable of rotating relative to the housing about the axis; A main shaft is received in the rotor, the main shaft being rotatable relative to the rotor about the axis, wherein the rotor is rotatably disposed on the main shaft; An output shaft, which is at least partially disposed within the housing and is rotatable about the axis; A first planetary gear set, which is radially disposed between the rotor and the main shaft with the axis as its center, and provides a first reduction ratio between the rotor and the main shaft; and The second planetary gear set provides a second reduction ratio between the main shaft and the output shaft. The first planetary gear set includes a first ring gear fixed to the rotor, a first planet carrier fixed to the housing, and a first sun gear fixed to the spindle, and / or the second planetary gear set includes a second sun gear fixed to the spindle, a second ring gear fixed to the housing, and a second planet carrier fixed to the output shaft. The first planetary gear set and the second planetary gear set are disposed within the housing, wherein: The electric motor includes a stator fixed to the housing and disposed within the housing; The rotor includes: Rotor rings, which are radially disposed within the stator, A hub, which is rotatably mounted on the main shaft, and A rotor flange that extends radially between the hub and the rotor ring and securely connects the hub and the rotor ring; The rotor is radially supported on the first planetary gear set via the rotor ring and radially supported on the main shaft via the hub.

12. The vehicle of claim 11, wherein the first ring gear is fixed to the rotor ring, and the first ring gear, the first sun gear, and the plurality of first planetary gears of the first planetary gear set are all axially disposed between the rotor flange and the inner edge of the rotor ring.

13. The vehicle of claim 11, wherein the housing is partially formed by the engine oil pan.

14. The vehicle of claim 13, wherein the lubricant used for the gear set is engine oil.

15. The vehicle according to claim 11, wherein the stator of the electric motor is liquid-cooled.

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