Electric drive unit with coolant input to inverter

Abstract

An electric drive unit includes a carrier housing having a cavity with a sump, an electric motor having stator and rotor assemblies, and a controller having an inverter with an inverter mount. The electric drive unit includes a flow guide, the inverter mount defines an inlet that is fluidly coupled to an outlet port, the inverter further including a plurality of power semiconductors each having a respective heat sink thermally coupled thereto, the inverter mount and the flow guide defining a chamber in which the heat sinks reside, the outlet port being fluidly coupled to the rotor assembly; a reservoir coupled to one of the carrier housing or the motor housing; and a lubrication and cooling system coupled to the sump and the reservoir and configured to produce a flow of lubricant to the chamber and through the heat sinks therein.

Description

ELECTRIC DRIVE UNIT WITH COOLANT INPUT TO INVERTERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States provisional application no. 63 / 558,798, filed February 28, 2024, which is hereby incorporated by reference as though fully set forth herein.FIELD

[0002] The present disclosure relates to an electric drive unit with a lubrication system having a reservoir that is separated from a sump and which provides a cooling input to an inverter. BACKGROUND

[0003] There is an increasing interest in the electrification of vehicle drivelines of the type including an electric propulsion motor that delivers a rotary output ( / .e., torque) to an attached gearbox by way of, for example, a drive gear. Implementation of such drivelines may typically involve the use of power electronics to energize the electric propulsion motor, which generates heat during operation. The gearbox typically includes a transmission employing a variety of moving components such as sprockets, chains, meshing gears, and combinations thereof to implement a desired output speed and torque performance. Thus, one consideration in the development of such drivelines involves lubrication of the various moving and / or load bearing components as well as cooling of various heat dissipation components, it would be useful to identify implementation efficiencies in addressing these considerations.SUMMARY

[0004] In accordance with one implementation, an electric drive unit is provided that includes a carrier housing having a gearbox cavity that includes a sump, a motor assembly having a motor housing fixedly coupled to the carrier housing and an electric motor received in the motor housing having a stator assembly and a rotor assembly rotatable about a motor axis. The motor assembly further includes a motor controller received in the motor housing configured to control a rotational speed of the rotor assembly. The electric drive unit further includes a reservoir coupled to one of the carrier housing or the motor housing wherein the reservoir is separate from and elevated relative to the sump. The electric drive unit still further includes a lubrication and cooling system including a pump assembly and a heat exchanger, wherein the pump assembly includes a scavenge pump configured to transfer lubricant drawn from the sump through a scavenge intake conduit to the reservoir through a scavenge output conduit, and a main pump configured to transfer lubricant drawn from the reservoir through a main intake conduit through the heat exchanger through a main output conduit and into the motor housing. The motor assembly has first and second coolant flow paths for lubricant wherein a first volume of lubricant flows along the first coolant flow path and a second volume of lubricant greater than the first volume flows along the second coolant flow path wherein lubricant from the second volume is directly returned to the reservoir, in a further implementation, the first coolant flow path extends through the rotor assembly while the second coolant flow path extends through the stator assembly.

[0005] In another implementation, an electric drive unit is provided that includes a carrier housing having a gearbox cavity that includes a sump, a motor assembly having a motor housing fixedly coupled to the carrier housing and an electric motor received in the motor housing having a stator assembly and a rotor assembly rotatable about a motor axis. The motor assembly further includes a motor controller in the motor housing configured to control a rotational speed of the rotor assembly and an inverter wherein the inverter has an inverter mount, an outlet port, and a flow guide. The inverter mount defines an inlet that is fluidly coupled to the outlet port. The inverter further includes a plurality of power semiconductors each having a respective heat sink thermally coupled thereto wherein the inverter mount and the flow guide define a chamber in which the heat sinks reside. The outlet port is fluidly coupled to the rotor assembly. The electronic drive unit further includes a reservoir coupled to one of the carrier housing or the motor housing, and a lubrication and cooling system coupled to the sump and the reservoir and configured to produce a flow of lubricant to the chamber and through the heat sinks therein. A first portion of the lubricant flow exiting the chamber passes through the inlet to and through the rotor assembly via passing through the outlet port wherein the first portion is discharged from the rotor assembly and drains to the sump. A second portion of the lubricant flow exiting from the chamber passes through the flow guide towards and through the stator assembly, lubricant from the second portion being directly returned to the reservoir, wherein the second portion is greater than the first portion.

[0006] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in thissummary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0008] Figures 1 and 2 are isometric views of an exemplary electric drive unit constructed in accordance with the teachings of the present disclosure;

[0009] Figure 3 is a side elevation view of the electric drive unit of Figure 1;

[0010] Figure 4 is a section view taken along the line 4-4 of Figure 3;

[0011] Figure 5 is a section view of a portion of the electric drive unit ofFigure 1 illustrating a portion of a motor assembly;

[0012] Figure 6 is an isometric view of a portion of the electric drive unit of Figure 1 illustrating a pump assembly;

[0013] Figure 7 is an isometric view of a portion of the electric drive unit of Figure 1 illustrating a pump mount on a housing assembly;

[0014] Figure 8 is an isometric view of a portion of the housing assembly;

[0015] Figure 9 is an isometric view of a portion of the electric drive unit of Figure 1 depicting an inlet screen in a gearbox cavity formed in the housing assembly;

[0016] Figure 10 is an isometric view of a portion of the electric drive unit of Figure 1 depicting a reservoir structure;

[0017] Figure 11 is an isometric view of a portion of the electric drive unit of Figure 1 depicting the motor assembly and a lubrication and cooling system;

[0018] Figure 12 is a section view of a portion of the motor assembly that depicts a motor controller in more detail;

[0019] Figure 13 is a section view of a portion of the electric drive unit of Figure 1 taken along a motor axis of the motor assembly;

[0020] Figure 14 is an enlarged portion of Figure 13;

[0021] Figure 15 is an isometric view of a portion of the electric drive unit of Figure 1 depicting a portion of the lubrication and cooling system that is disposed in the gearbox cavity in the housing assembly;

[0022] Figure 16 is a section view of a portion of the motor assembly illustrating the stator assembly and a flow guide in more detail;

[0023] Figure 17 is an isometric view of a portion of the motor assembly;

[0024] Figures 18 and 19 are isometric views of portions of the housing assembly;

[0025] Figure 20 is a section view of a portion of the electric drive unit of Figure 1 that depicts a portion of a transmission;

[0026] Figure 21 is an isometric view of a portion of the electric drive unit of Figure 1 that depicts a portion of a transmission;

[0027] Figure 22 is an exploded, isometric view of a portion of the motor assembly showing the motor controller in greater detail;

[0028] Figure 23 is an isometric view of an inverter mount of an inverter of the motor controller;

[0029] Figure 24 is an isometric view of a circuit board cap installed on the inverter mount of Figure 23;

[0030] Figure 25 is an isometric view of a portion of the motor controller of the electric drive unit of Figure 1 ;

[0031] Figure 26 is an isometric view of a portion of the motor controller of Figure 25;

[0032] Figure 27 is a section view of a portion of the transmission depicting a plurality of lubrication implementations;

[0033] Figure 28 is a section view of a portion of the transmission depicting a further lubrication implementation involving wheel bearings of an axle shaft; and

[0034] Figure 29 is a section view of a portion of the transmission depicting a further lubrication implementation.

[0035] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.DETAILED DESCRIPTION

[0036] Figures 1 and 2 are isometric views of an exemplary electric drive unit constructed in accordance with the teachings of the present disclosure, generally indicated by reference numeral 10. The electric drive unit 10 is configured to provide propulsion drive for a vehicle (not shown) in one implementation and may be adapted to a variety of platforms, such as a partial or a fully electrified vehicle powertrain. The electric drive unit 10 can include a housing assembly 12 and a motor assembly 14.

[0037] Figure 3 is a side elevation view of the electric drive unit 10 of Figure 1 , which shows the motor assembly 14 in relation to the housing assembly 12.

[0038] Figure 4 is a section view of the electric drive unit 10 taken along the line 4-4 of Figure 3. The electric drive unit 10 further includes a differentialassembly 16, a transmission 18, a pair of ( / .a., a first and a second) output axle shafts 20, and a lubrication and cooling system 22 (Figs. 1-3).

[0039] Before proceeding to a further detailed description, an overview will be set forth. As described in the Background, it would be useful to realize efficiencies in implementing an electric drive unit with respect to either lubrication considerations, cooling considerations, or both. The housing assembly 12 of the electric drive unit 10 includes, in implementations, a carrier housing that defines a cavity that includes an oil (hereinafter “lubricant”) sump. The electric drive unit also includes a separate reservoir configured to hold lubricant and which is elevated relative to the sump. Lubricant as used herein can be used as both a lubricating liquid as well as a cooling fluid for cooling components (e.g., power semiconductors) that generate heat during operation. The sump and the reservoir are coupled by fluid conduits as will be described. The lubrication and cooling system 22 has a pump assembly that includes a so- called scavenge pump that pumps lubricant drawn from the sump to the reservoir. The pump assembly also has a main pump that transfers lubricant that is drawn from the reservoir through a heat exchanger and thereafter throughout the electric drive unit for both lubrication and cooling purposes.

[0040] In operation, the scavenge pump needs to fill the reservoir faster than the main pump can drain it. In a scenario where all the lubricant (oil) ends up in the sump, the scavenge pump would need to be appreciably larger than the main pump, perhaps on the order of twice as large ( / .e., 2:1). This larger scavenge pump would occupy an enlarged volume in the electric drive unit and would consume a greater amount of energy to support its operation.

[0041] However, rather than configuring the lubricating and cooling system so that all of the lubricant (oil) ends up in the sump, the electric drive unit 10, in implementations, instead is configured so that a majority of the lubricant (oil) is returned directly to the reservoir. Accordingly, the scavenge pump can be generally reduced in size (j.e., can be closer in size to the main pump). Implementations consistent with these teachings exhibit the improvements of reduced size, reduced weight, and reduced energy consumption.

[0042] With continued reference to Figure 4, the housing assembly 12 can be configured in any desired manner and can define a gearbox cavity 30 into which the transmission 18 and the differential assembly 16 can be received. The housing assembly 12 defines an output axis 32 about which the output axle shafts 20 rotate. In the particular example provided, the housing assembly 12 includes a carrier housing 36, which is formed of first and second housing members 40 and 42, respectively, and a pair of axle tubes 44. The first and second housing members 40 and 42 are mated to one another about a plane that is transverse (e.g., perpendicular) to the output axis 32 and can each define an axle tube mount 46. Each of the axle tubes 44 is received into an axle tube aperture 48 formed in a corresponding one of the axle tube mounts 46 and is fixedly coupled to a corresponding one of the first and second housing members 40 and 42. In the particular example provided, the carrier housing 36 has the gearbox cavity 30.

[0043] The motor assembly 14 can include a motor housing 50, an electric motor 52 and a motor controller 54. The motor housing 50 can be fixedly coupled to the carrier housing 36 and can define a motor cavity 60 into whichthe electric motor 52 and the motor controller 54 can be received. The electric motor 52 may comprise an electric propulsion motor and can include a stator assembly 62, which is received in the motor cavity 60 and is fixedly coupled to the motor housing 50, and a rotor assembly 64 that is also received, generally, in the motor cavity 60, and more particularly, is received in the stator assembly 62. The rotor assembly 64 is rotatable about a motor axis 66 relative to the stator assembly 62. The motor assembly 14 extends axially along the motor axis 66 between a proximal end 196 proximate the motor controller 54 and a distal end 198 where the rotor output shaft 82 drives the transmission 18.

[0044] Figure 5 is a section view of a portion of the electric drive unit of Figure 1 illustrating a portion of the motor assembly 14. As shown in Figure 5, the stator assembly 62 includes a stator core 70 and a plurality of sets of field windings 72 that are wound about the stator core 70. The rotor assembly 64 includes a rotor 80 and a rotor output shaft 82. The rotor 80 can include a rotor lamination stack 86, which can be formed of a plurality of annular rotor laminations 88, and a plurality of magnets 90 that can be received in magnet apertures (not specifically shown) in the rotor lamination stack 86. The rotor output shaft 82 can be received within and fixedly coupled to the annular rotor laminations 88 and can optionally extend into the gearbox cavity 30.

[0045] The rotor output shaft 82 can define a hollow cavity 94 that is open on a first axial end 92 (Fig. 13) of the rotor output shaft 82 proximate the transmission 18. The cavity 94 is closed on a second axial end 96 (Fig. 13) opposite the first axial end 92 by an end cap 98 (Fig. 13). The end cap 98 has a return cavity 102 in fluid communication with the hollow cavity 94.

[0046] With reference to Figures 4-5, a pair of rotor bearings 100 can be empioyed to support the rotor assembly 64 for rotation about the motor axis 66 relative to the motor housing 50. In the example provided, a first one of the rotor bearings 100 is mounted to the rotor output shaft 82 and the first housing member 40 of the carrier housing 36, while a second one of the rotor bearings 100 is mounted to the rotor output shaft 82 and a bearing support 104 (Fig. 5).

[0047] As shown in Figure 5, the stator assembly 62 further includes a stator sleeve assembly 110. The stator sleeve assembly 110 can include a stator sleeve 112 and a pair of stator end caps 114 (only one shown). The stator sleeve 112 can be formed of a non-magnetically susceptible, electrically insulating material, such as carbon fiber. The stator sleeve 112 can extend the length of the stator core 70 and can be fixedly coupled to the inside circumferential surface of the stator core 70. The stator end caps 114 are annular end plates that are fixedly and sealingly coupled to the opposite ends of the stator sleeve 112. A seal is mounted to each of the stator end caps 114 and forms a seal between the bearing mount 104 and the stator end cap 114. Accordingly, it will be appreciated that the stator sleeve assembly 110 forms a sealed cavity in which the rotor assembly 64 can rotate about the motor axis 66. In other words, the stator sleeve assembly 110 is configured to seal the rotor assembly 64 from the stator core 70.

[0048] The motor controller 54 can be received in the motor housing 50 and is disposed coaxially about the motor axis 66. The motor controller 54 can include an inverter 120 that is electrically coupled to the stator assembly 62 and operated by control circuitry in the motor controller 54 to control operation of the electric motor 52. For example only, the motor controller 54 can beconfigured to control a rotational speed of the rotor assembly 64, particularly the rotor output shaft 82, relative to the stator assembly 62.

[0049] Returning to Figure 4, the differential assembly 16 includes a differential input member 130, which is rotatable about the output axis 32, and a pair of (i.e., first and second) differential output members 132 that are rotatable about the output axis 32 relative to the differential input member 130. The differential assembly 16 can be constructed in any desired manner. For example, the differential assembly 16 may include a differential gearset or one or more friction clutch packs for transmitting rotary power between the differential input member 130 and the differential output members 132. If a differential gearset is employed, the differential gearset could be configured with differential pinion gears 134 (one shown in Fig. 4), which could have a bevel or helical configuration, are employed to transmit rotary power to a pair of side gears, or as one or more planetary gearsets having a sun gear, planet gears supported on a planet carrier, and a ring gear.

[0050] In the particular example provided, the differential assembly 16 includes a differential gearset having differential pinion gears with a bevel configuration. The differential pinion gears are mounted to the differential input member 130 (i.e., a differential case in the example provided) and are rotatable about one or more axes that are perpendicular to the output axis 32. In this regard, the differential pinions can be rotatably mounted on a cross-pin 136 that is fixedly coupled to the differential input member 130 and which is disposed perpendicular to the output axis 32. The differential pinions are meshingly engaged with a pair of side gears ( / .e., the differential output members 132 in the example provided). The differential assembly 16 may comprise an “open”differential assembly and / or variations thereof to provide limited slip, locking, and / or disconnecting capabilities, as desired.

[0051] The transmission 18 is configured to transmit rotary power between the motor assembly 14, particularly the rotor output shaft 82, and the differential assembly 16, particularly the differential input member 130. In other words, the differential input member 130 is configured to be driven by the rotary output of the transmission 18. The transmission 18 can comprise any means for transmitting rotary power, including a chain drive ( / .©., one or more sets of sprockets and chains), a belt drive ( / .e.7one or more sets of pulleys and belts), gearing ( / .e., one or more sets of meshing gears) and / or combinations thereof to perform a desired speed reduction and torque multiplication function between the electric motor 52 and the differential assembly 16. it will be appreciated that the rotary power transmitting means can be of a fixed speed ratio or could be configured to provide two or more desired speed ratios. In the example provided, the rotary power transmitting means comprises gearing, and more specifically, a first portion 56, which provides a fixed speed ratio and receives rotary power from the rotor output shaft 82, and a second, multi-speed portion 58 that receives rotary power from the first portion 56 and outputs rotary power to the differential input member 130.

[0052] Each of the output axle shafts 20as viewed in Fig. 4, a first axle shaft 20 on the left side of the differential assembly 16 and a second axle shaft 20 on the right side ) is received through the carrier housing 36 and can be coupled to a respective one of the differential output members 132 for rotation therewith. Each of the output axle shafts 20 is coaxially received in acorresponding one of the axle tubes 44 and is supported for rotation about the output axis 32 relative to the housing assembly 12.

[0053] As illustrated in Figures 2-3, the lubrication and cooling system 22 can include a pump assembly 140, a heat exchanger 142, a filter 144, and a plurality of conduits, which may be integrally formed with the housing assembly 12 and / or comprise discrete tubes and / or hoses, as described below in exemplary implementations.

[0054] Figure 6 is an isometric view illustrating the pump assembly 140. The pump assembly 140 can comprise a scavenge pump 150 and a main pump 152, both of which are driven by an electric pump motor 154. The main pump 152 is configured to provide a flow of lubricant and coolant (e.g., oil) having a relatively lower volumetric flow and relatively higher pressure than a flow that is provided by the scavenge pump 150. The pump assembly 140 further includes a mounting flange 156 that defines a scavenge inlet 160, a scavenge outlet 162, a main inlet 164 and a main outlet 166.

[0055] Figure 7 is an isometric view illustrating a pump mount 170. The mounting flange 156 of the pump assembly 140 is mounted ( / .e., fixedly and sealingly coupled) to the pump mount 170 formed on the carrier housing 36. In the example shown, the pump mount 170 is formed on the first housing member 40, but it will be appreciated that the pump mount 170 could be formed on the motor housing 50. A plurality of conduits (i.e., a scavenge intake conduit 172, a scavenge output conduit 174, a main intake conduit 176 and a main output conduit 178) intersect the pump mount 170 and are configured to be fluidly coupled to the scavenge inlet 160, the scavenge outlet 162, the main inlet 164and the main outlet 166, respectively, when the pump assembly 140 is mounted to the carrier housing 36.

[0056] Figure 8 is an isometric view of a portion of the carrier housing 36 showing conduits 172, 174, 176, and 178 in greater detail. Figure 8 shows the carrier housing 36 defining the gearbox cavity 30 which includes a sump 180. The scavenge intake conduit 172 extends between the sump 180 and the pump mount 170. The scavenge intake conduit 172 may be unitarily and integrally formed with the carrier housing 36. The scavenge intake conduit 172 is fluidly coupled to the scavenge inlet 160 on the scavenge pump 150, wherein the scavenge inlet 160 is in fluid communication with the sump 180. In implementations, filtering of the sump lubricant may be desired, as described immediately below.

[0057] Figure 9 is an isometric, enlarged view of the portion of the carrier housing 36 of Figure 8 depicting an inlet screen 184. The inlet screen 184 can be mounted to the carrier housing 36 in the sump 180 and can be in fluid communication with the scavenge intake conduit 172, and thus also the scavenge inlet 160, to screen ( / .©., coarsely filter) lubricant that is drawn from the sump 180 through the scavenge intake conduit 172 to the scavenge pump 150.

[0058] Returning to Figure 8, a reservoir 190 is illustrated. The reservoir 190 could be a discrete component or a structure that can be mounted to the housing assembly 12, in an implementation (j.e., the reservoir 190 can be fixedly coupled to one of either the carrier housing 36 or the motor housing 50). The reservoir 190 can be separate from the sump 180 and may be elevated with respect to the sump 180. In the example provided, the reservoir 190includes a reservoir structure 192, which is formed by the carrier housing 36 (and more specifically, by the first housing member 40), and a reservoir cover 194 (Fig. 1) that is fixedly and sealingly engaged to the reservoir structure 192. The reservoir structure 192 can be relatively deep so that it is capable of holding a majority of the lubricant that is circulated through the lubrication and cooling system 22 (Fig. 1). The reservoir structure 192 includes a circumferential sidewall 216 extending from a bottom surface 204 (Fig. 10) to define an interior 218 for holding a quantity of lubricant. Lubricant exits the scavenge pump 150 via the scavenge outlet 162 and is transmitted through the scavenge output conduit 174 to the reservoir 190. In other words, the scavenge pump 150 is configured to transfer lubricant drawn from the sump 180 through the scavenge intake conduit 172, to the reservoir 190 through the scavenge output conduit 174.

[0059] Figure 10 is an isometric view depicting the reservoir 190 in greater detail. The scavenge output conduit 174 can intersect the interior 218 of the reservoir structure 192 at a first elevation, the main intake conduit 176 can intersect the interior 218 of the reservoir structure 192 at a second elevation that is lower than the first elevation, and a breather conduit 200 can intersect the interior 218 of the reservoir structure 192 at a third elevation that is higher than the first elevation. In the example provided, the scavenge output conduit 174 extends through a first boss 202 that extends upwardly from the bottom surface 204 of the reservoir structure 192, the main intake conduit 176 is formed through the bottom surface 204 of the reservoir structure 192, and the breather conduit 200 extends through a second boss 206 that extends upwardly from the bottom surface of the reservoir structure 192.

[0060] It will be appreciated that air can interact with the liquid lubricant that is circulated through the electric drive unit 10 during its operation, particularly when the liquid lubricant is dispensed onto or drains from various rotating components, so that foam can be created and / or air can be entrained into the lubricant. The positioning of an outlet 226 of the scavenge output conduit 174 at a location in the interior 218 of the reservoir 190 that is relatively higher than an inlet 228 of the main intake conduit 176 during normal operation (i.e., within predetermined ranges for pitch and roll) of the electric drive unit 10 (Fig. 1) provides a region within the reservoir 190 where air can separate from the liquid lubricant before the liquid lubricant is drawn from the reservoir 190 via the main intake conduit 176. Air released from the liquid lubricant in the reservoir 190 can be discharged from the reservoir 190 via the breather conduit 200, the inlet 230 of which is located at a higher level in the reservoir 190 than the outlet 226 of the scavenge output conduit 174 during normal operation of the electric drive unit 10. An outlet 232 of the breather conduit 200 can be located in the gearbox cavity 30 as shown in Figure 27.

[0061] If desired, the reservoir 190 can include one or more baffles 210. In the example provided, the reservoir 190 includes a single baffle 210 that is unitarily and integrally formed with the reservoir structure 192 and which forms two distinct chambers 212a and 212b within the reservoir structure 192. The outlet 226 for the scavenge output conduit 174 and the inlet 230 for the breather conduit 200 are disposed in a first one of the chambers 212a, while the inlet 228 of the main intake conduit 176 is disposed in a second one of the chambers 212b. A through-hole 214 can be formed through the baffle 210 to fluidly couple the chambers 212a and 212b. It will be appreciated that liquid lubricantintroduced into the reservoir 190 is initialiy received in the first one of the chambers 212a and that the through-hole 214 permits substantially de-aeriated liquid lubricant to flow into the second one of the chambers 212b. Lubricant in the reservoir 190 that enters the inlet 228 of the main intake conduit 176 can be transmitted through the main intake conduit 176 to the main inlet 164 of the main pump 152.

[0062] With continued reference to Figure 8, the scavenge intake conduit 172 fluidly couples the inlet screen 184 in the sump 180 to the scavenge pump 150 (j.e., the scavenge inlet 160 thereof), the scavenge output conduit 174 fluidly couples the scavenge pump 150 ( / .e., the scavenge outlet 162 thereof) to the reservoir 190, the main intake conduit 176 fluidly couples the reservoir 190 to the main pump 152 (Le., the main inlet 164 thereof), and the main output conduit 178 fluidly couples the main pump 152the main outlet 166 thereof) to the heat exchanger 142 (Fig. 2) in a manner described below. In this regard, the main output conduit 178 extends between the main pump 152 and a fitting 234, best shown in Figure 11. The remainder of the lubricant flow path from the main pump 152 to the heat exchanger 142 will be described below. Additionally, it should be understood that what is being fluidly coupled as described in the above paragraph is the lubricant.

[0063] Figure 11 is an isometric view depicting the motor assembly 14 and a lubrication and cooling system 22 in greater detail. And now with reference to Figures 2, 6 through 8 and 11 , liquid lubricant received by the main pump 152 from the main inlet 164 is pressurized and transmitted to the main outlet 166, where it can be distributed through the electric drive unit 10 in a desired manner. In the example provided, the main outlet 166 is coupled in fluidconnection via the main output conduit 178 to the fitting 234, which can be mounted or otherwise formed in the carrier housing 36, particularly the first housing member 40. A heat exchanger feed conduit 220 is fluidly coupled between the fitting 234 and the heat exchanger 142 such that main pump 152 is fluidly coupled with, and can transmit the pressurized liquid lubricant to, the heat exchanger 142. Cooled liquid lubricant exits the heat exchanger 142 and is routed through a heat exchanger return conduit 222 to a filter base 224 formed in the motor housing 50. The heat exchanger 142 is therefore fluidly coupled to the filter base 224. The filter base 224 is configured for a filter 144 to be attached thereto. Liquid lubricant flowing into the filter base 224 is routed through the filter 144 and thereafter back through the filter base 224 and discharged into the motor assembly 14, particularly, discharged into the motor housing 50 thereof, to cool and lubricate portions of the motor assembly 14 as more particularly described below. Accordingly, the main pump 152 is configured to transfer lubricant drawn from the reservoir 190 through the main intake conduit 176 to the heat exchanger 142 via the main output conduit 178, fitting 234, and the heat exchanger feed conduit 220, in an implementation.

[0064] Figure 12 is a section view of a portion of the motor assembly 14 depicting the motor controller 54 in more detail. The liquid lubricant routed from the output of the filter 144 through the filter base 224 is directed through the motor housing 50 and discharged into the motor controller 54 for cooling the inverter 120, and thereafter cooling the stator assembly 62 and the rotor assembly 64. A quantity (flow amount) of lubricant being discharged from the output of the filter 144 into the motor controller 54, specifically into the inverter120, is indicated at 182 and may be referred to as the cooiing input to the inverter 120.

[0065] In the example shown in Figure 12, the inverter 120 includes an inverter mount 250, a circuit board 252, a positive bus bar 254, a ground bus bar 256, a plurality of phase bus bars 258 (only one shown), a plurality of power semiconductors 260 (only one shown in Figure 12), a plurality of heat sinks 262 (only one shown in Figure 12), and a circuit board cap 264. The inverter mount 250, the circuit board 252, the positive bus bar 254, the ground bus bar 256, the phase bus bars 258, the power semiconductors 260, and the heat sinks 262 can be configured in a manner that is generally similar to that which is described in detail in United States application serial no. 17 / 880,746 filed August 4, 2022 entitled “Electric Drive Unit”, the disclosure of which is incorporated by reference as if fully set forth in detail herein. Briefly, the inverter mount 250 can include an end plate 270 and an outer annular wall 272 that extends about the outer circumferential end of the end plate 270. The circuit board 252 includes circuitry for monitoring and controlling the operation of the electric motor 52. The positive bus bar 254 is configured to be electrically coupled to a source of electrical power (not shown), such as a vehicle battery, the ground bus bar 256 is configured to be electrically coupled to an electrical ground (not shown), and each of the phase bus bars 258 is electrically coupled to a phase lead or terminal (not shown in Figure 12) of a corresponding one of the sets of field windings 72. The power semiconductors 260 are electrically coupled to the circuit board 252, the positive bus bar 254 and the ground bus bar 256 and are arranged in sets, with each set of the power semiconductors 260 being electrically coupled to an associated one of the phase bus bars 258.

[0066] During the operation of the motor assembly 14, circuitry included on the circuit board 252 controls the sets of power semiconductors 260 to thereby control the supply of electrical power from the positive bus bar 254 to each of the sets of field windings 72. The heat sinks 262 are thermally coupled to the power semiconductors 260 to receive heat therefrom that is generated during the operation of the motor assembly 14. The inverter mount 250 is configured to segregate the circuit board 252, the positive bus bar 254, the ground bus bar 256 and the phase bus bars 258 from the heat sinks 262.

[0067] In the example provided, a seal 280 is mounted between the outer annular wall 272 and the motor housing 50 to define a first plenum 282 therebetween. The first plenum 282 extends about the circumference of the motor housing 50 and is configured to receive the flow 182 of liquid lubricant and provides a volume in which the pressure of the liquid lubricant can equalize before the liquid lubricant flows into the inverter 120.

[0068] The arrangement of the motor housing 50 and the inverter mount 250 is configured to allow the liquid lubricant to flow from the first plenum 282 to a chamber 208 in which the heat sinks 262 reside. The chamber 208 is defined in part by the inverter mount 250 and a flow guide 330 to be described below. The lubricant flows to and through the heat sinks 262 and is operative to conduct heat away from the heat sinks 262 and thus also away from the power semiconductors 260. The lubricant flow exits the chamber 208 and is discharged into an annular space 284 in which end turns 72a of the sets of field windings 72 are disposed. The liquid lubricant can (primarily) flow over an axial end of the end turns 72a and then be directed toward the stator core 70.

[0069] A first portion of the flow of liquid lubricant flowing toward the stator core 70 can be diverted to cool the rotor assembly 64, and will be referred to as the first portion 186, while a second portion of the flow of liquid lubricant that flows toward the stator core 70 can be designated the second portion 188, and can be directed in a radially outward direction through the end turns 72a toward the motor housing 50 and into a second annular plenum 290. Liquid lubricant in the second annular plenum 290 can flow into a plurality of stator cooling channels 294 that are formed longitudinally through the stator core 70. in the example provided, the stator cooling channels 294 are formed as holes in the laminations that form the stator core 70, and the holes in the laminations are staggered so that the stator cooling channels 294 twist (e.g., helically) as they progress through the stator core 70.

[0070] It is possible that air may be entrained in the liquid lubricant flowing through the heat sinks 262 and that the air may separate from the liquid lubricant as it flows through the heat sinks 262. Air that separates from the liquid lubricant proximate the heat sinks 262 can be vented through an inverter bleed conduit (not specifically shown in Figure 12) that vents air and liquid lubricant into the carrier housing 36 ( / .e., into the gearbox cavity 30 and to the sump 180). In the example provided, a relatively small inverter air bleed orifice 398 (Figure 13) is provided between the chamber 208, in which the heat sinks 262 are disposed, and the inverter bleed conduit (best shown in Figures 18-19, which depicts an inverter air bleed drain 372 that vents to the gearbox cavity 30).

[0071] The first portion 186 of the initial flow 182 of lubricant is destined to flow through the rotor assembly 64 and will be discharged therefrom and drain to the sump 180. A second portion 188 of the initial flow 182 of lubricantis destined to flow through the stator assembly 62 and will be discharged therefrom and directed generally to the reservoir 190. As will described herein, some of the first and second portions 186, 188 can be used for lubrication. In an implementation, the second portion 188 is greater than the first portion 186. As described above, reducing the amount of lubricant being drained into the sump 180 allows for a reduced size scavenge pump 150, and in an implementation, a scavenge pump 150 that approaches the size of the main pump 152. A description of a first coolant flow path in which the first portion 186 of lubricant (j.e., a first volume) travels through the rotor assembly 64 to the sump 180 will be set forth followed by a description of a second coolant flow path in which the second portion 188 of lubricant ( / .e., a second volume) travels through the stator assembly 62 to the reservoir.

[0072] With continued reference to Figure 12, the first portion 186 passes through a space 300 and thereafter through an inlet 350 that is disposed between the stator sleeve assembly 110 and an annular inner wall 302 of the inverter mount 250 that is fixedly coupled to (e.g., unitarily and integrally formed with) the end plate 270. The inlet 350 is fluidly coupled to the outlet port 306. The first portion 186 can then flow out of an outlet port 306 defined by the inverter mount 250 and formed through the end plate 270. The outlet port 306 is fluidly coupled to the rotor assembly 64. From the outlet port 306, the first portion 186 is directed to the rotor assembly 64 as described in greater detail below.

[0073] With reference to Figures 13 through 15, a cover 308 is mounted to the motor housing 50 to close an end of the motor housing 50 at the proximal end 196 of the motor assembly 14. The motor controller 54, including theinverter 120, is disposed at the proximal end 196. The cover 308 can include a fitting 310 having a first end 312, which is coupled in fluid connection to the outlet port 306 on the inverter mount 250, and a second end 314 to which a first rotor coolant supply line 316 can be coupled. The first rotor coolant supply line 316 can transmit liquid lubricant to a port 318 in the housing assembly 12 that is located proximate the distal end 198 of the motor assembly 14. The rotor coolant supply line 316 is shown, partially in hidden line format, in Figure 11.

[0074] The port 318 is fluidly coupled to a second rotor coolant supply line 320 that is disposed in the gearbox cavity 30 and extends through an input pinion 326, which is rotatably coupled to (e.g., integrally and unitarily formed with) the rotor output shaft 82. The second rotor coolant supply line 320 can extend into a rotor coolant feed tube 322 that is mounted to the rotor output shaft 82 concentrically about the motor axis 66. Liquid lubricant — the first portion 186 — that flows through the second rotor coolant supply line 320 is received by the rotor coolant feed tube 322. The first portion 186 of lubricant enters the rotor coolant feed tube 322 and into the hollow cavity 94 at the open, first axial end 92 and flows towards the second axial end 96. This flow is generally in the direction of the distal end 198 to the proximal end 196 with respect to the motor assembly 14. The first portion 186 of the liquid lubricant encounters a return cavity 102 formed in the end cap 98 and is directed to and exits the rotor coolant feed tube 322 in a radially outward direction about the rotor coolant feed tube 322 towards and through one or more rotor coolant return passages 324.

[0075] The rotor coolant return passages 324 extend between the second axial end 96 and the first axial end 92. The rotor coolant returnpassages 324 are concentrically arranged about the rotor coolant feed tube 322 and allows the return flow of the first portion 186 of the liquid lubricant. The first portion 186 of the lubricant flows in the rotor coolant return passages 324 from second axial end 96 to the first axial end 92 ( / .©., from the proximal end 196 to the distal end 198 as taken with respect to the motor assembly 14). The return cavity 102 has the effect of reversing the flow direction of the first portion 186 of lubricant through the rotor assembly 64. The first portion 186 of lubricant flows towards an open axial end of an input pinion 326 on the rotor output shaft 82. The return flow of the first portion 186 of the liquid lubricant is discharged from the input pinion 326 / rotor output shaft 82 into the gearbox cavity 30 and where it can drain to the sump 180, to be drawn by the scavenge pump 150 and directed to the reservoir 190. Accordingly, the first portion 186 of lubricant flows through and cools the rotor assembly 64. The first portion 186 discharged from the input pinion 326 is shown as lubricant discharge 374 in Figure 21. Substantially all the lubricant that flows into the rotor assembly 64 (approximately one-third of the total volume, in an implementation) is eventually discharged into the gearbox cavity 30 and drains to the sump 180.

[0076] Figure 16 is a section view illustrating the stator assembly 62 and the flow guide 330 in greater detail. The flow guide 330 can be employed to aid in directing the flow of liquid lubricant between the heat sinks 262 and the second annular plenum 290 and / or balancing the relative flow rates of the liquid lubricant that is to be directed to the rotor assembly 64 on the one hand versus directed to the stator cooling channels 294 in the stator core 70, on the other hand. The flow guide 330 can include an annular flange 332 and an annular guide member 334. The annular flange 332 can extend in a radial directionbetween the end turns 72a and the motor housing 50 and can optionally form a barrier between the first and second annular plenums 282 and 290. The annular flange 332 can extend in an axial direction between the stator core 70 and the heat sinks 262 and can define a plurality of flow openings 340 that permit fluid flow' between the radially outer side of the end turns 72a and the second annular plenum 290. The annular guide member 334 can extend from the annular flange 332 in a direction away from the stator core 70 and can extend radially inward of the heat sinks 262 and radially outward of an outer circumferential surface of the end turns 72a of the sets of field windings 72. In the particular example shown, the annular guide member 334 extends over a portion of an axial end of the end turns 72a and aids in guiding the flow of liquid lubricant that exits the heat sinks 262 over the axial end of the end turns 72a, where it can flow along the radially inner side of the end turns 72a toward the stator core 70.

[0077] The size of the flow openings 340 in the annular flange 332 of the flow guide 330 ( / .e., a first configuration) and the size of the inlet 350a second configuration) can be tailored to balance the respective flows or flow volumes of liquid lubricant that are employed to cool the stator assembly 62 and the rotor assembly 64 in a desired manner ( / .e., the first portion 186 and the second portion 188). In the example provided, approximately two-thirds of the total volumetric flow of liquid lubricant is employed to cool the stator assembly 62 (j.e., the second portion 188 corresponding to the second volume), which goes to the reservoir 190, while approximately one-third of the total volumetric flow of liquid lubricant is employed to cool the rotor assembly 64 ( / .e., the first portion 186 corresponding to the first volume), which goes to the sump180. The flow guide 330 Is therefore configured to direct lubricant discharged from the filter 144 and through the filter base 224 into (i) the first portion 186 ( / .e., the first volume) through the first coolant flow path that includes the inlet 350, the outlet port 306, and the rotor assembly 64 as described herein and (ii) the second portion 188 (i.e., the second volume) through the second coolant flow path that includes the flow openings 340 and the stator assembly 62, particularly the stator cooling channels 294.

[0078] Figure 17 is an isometric view of a portion of the motor assembly 14 depicting the stator core 70 and end turns 72a in greater detail. A phase terminal 74 is electrically coupled to each phase of the windings 72. Each phase terminal 74 may include further features such as a seal groove and a connecting feature that aids in fixedly and electrically coupling the phase terminal to an associated one of the phase busbars. A plurality of flow passages 76 facilitate flow of lubricant towards the second plenum 290 destined for the stator cooling channels 294.

[0079] Figure 22 is an exploded, isometric view of a portion of the motor assembly 14 showing the motor controller 54 in greater detail. The flow guide 330 includes a plurality of flow openings 340 as described above. The motor controller 54 further includes various busbars, circuit board, and the like as depicted in cross-section in Figure 12 and also described above.

[0080] Figure 23 is an isometric view of the inverter mount 250 of the inverter 120.

[0081] Figure 24 is an isometric view of the circuit board cap 264 installed on the inverter mount 250.

[0082] Figure 25 is an isometric view of the motor controller 54, including the inverter 120. As shown, the inverter 120 includes a plurality of power semiconductors 260 (only one specifically identified by reference number) as well as a corresponding plurality of respectively thermally coupled heatsinks 262 (only one specifically identified by reference number).

[0083] Figure 26 is an isometric view of a portion of the inverter 120.

[0084] Referring again to Figure 13, liquid lubricant, particularly the second portion 188 thereof, that flows from the proximal end 196 to the distal end 198 and which exits the stator cooling channels 294 can be directed initially into the housing assembly 12, and then subsequently to the reservoir 190 as well as to other components for the lubrication and / or cooling purposes.

[0085] Figures 18 and 19 are isometric views of portions of the housing assembly 12. In particular, Figure 18 shows the first housing member 40 as viewed from an exterior point of view, and shows a motor mounting features into which the distal end 198 of the motor assembly 14 ( / .e., the input pinion 326 end) is inserted and mounted thereto. Figure 19 the same portion of the first housing member 40 as in Figure 18 but now as viewed from the opposite side. The following will describe features that are configured to direct the liquid lubricant to other components of electric drive unit 10 for the lubrication and / or cooling purposes of those components and to return a part of this flow of liquid lubricant to the reservoir 190.

[0086] In an implementation, substantially all of the second portion 188 of the lubricant flow through the stator flow channels 294 is discharged into a recess 354, which has an annular sidewall 356 that extends from a surface 352. The surface 352 confronts the stator core 70 including the stator coolingchannels 294, and in an implementation, the stator core 70 can abut the surface 352. The recess 354 may include one or more gear shaft feed orifices 358 that can be formed through the surface 352 and opening into the gearbox cavity 30 proximate components of the transmission 18, for example. Lubricant can flow through the gear shaft feed orifices 358.

[0087] Figure 20 is a section view of a portion of the transmission 18. The gear shaft feed orifices 358 can be employed to lubricate the bearings 360 that support respective shafts 362 on which various gears 364 of the transmission 18 are mounted. In some instances, liquid lubricant can be transmitted through the shaft(s) 362 to feed liquid lubricant to an associated bearing 360. The lubricant travel path is illustrated in dashed line format. Thus, as depicted in Figure 20, in an implementation, both the near-end bearing 360 ( / .e., near the feed point of gear shaft feed orifices 358) and the far-end bearing 360 can be fed liquid lubricant.

[0088] Returning to Figure 18, as another example, one or more gear mesh lubrication apertures 368 can be formed through the surface 352 on the housing assembly 12 and can provide liquid lubricant to a respective spray nozzle, as described below.

[0089] Figure 21 is an isometric view of a portion of the transmission 18. in the example provided, a single spray nozzle is employed and is unitarily and integrally formed with the first housing member 40 of the carrier housing 36. The spray nozzle includes a plurality of spray orifices 370 which are drilled into the first housing member 40 and intersect the gear mesh lubricant aperture 368 (Fig. 18). Liquid lubricant discharged from the spray orifices 370 is sprayed ontothe teeth of various gears 364 in the transmission 18 as well as input pinion 326.

[0090] In addition, the discharge 374 of lubricant from the open end of the input pinion 326 / rotor output shaft 82 will in part fall on a relatively low- speed gear 364, which will not only lubricate this gear but may create splash in an implementation. In an alternate implementation (e.g., to reduce drag), a baffle (not depicted) or the like can be employed to either entirely or partially limit the amount of lubricant hitting the gear 364.

[0091] It should be understood that the lubricant discharged from the rotor assembly 64 ( / .e., discharge 374), discharged into the gearbox cavity 30 via the inverter bleed drain 372, and discharged from the various gear shaft and gear mesh orifices (oilers) will be drain to the sump 180 and thereafter be drawn into the pump intake screen 184 and pumped up to the reservoir 190.

[0092] As a further example, and with reference to Figures 10, 13 and 18, a reservoir return conduit 380 can be formed into the housing assembly 12 and can have a first end as shown in Figure 18, which can receive a portion of the liquid lubricant that is discharged from the stator cooling channels 294 in the stator core 70 of the stator assembly 62 into the recess 354, and transmit the liquid lubricant directly to the reservoir 190. The liquid lubricant is discharged from the reservoir return conduit 380 through a return port 384 that is formed through the reservoir structure 192, and which is fluidly coupled to the reservoir return conduit 380. The return port 384 is disposed at one elevation that is above another elevation at which the main intake conduit 176 intersects the interior of the reservoir structure 192.

[0093] Figure 27 is a section view of the reservoir 190, the differential assembly 16, and one of the axle shafts 20 on a first side of the electric drive unit 10 The breather conduit 200 extends through the boss 206 and has the inlet 230 open to the reservoir 190 and the outlet 232 open to the gearbox cavity 30. The breather conduit 200 is configured so as to prevent the reservoir 190 from becoming pressurized. The breather conduit 200 is configured such that a discharge 376 of lubricant (shown in dashed-line format) is positioned over the windows of the differential assembly 16 in order to lubricate the differential components thereof.

[0094] It should be appreciated that in a further implementation, the bearing 382 can be lubricated (oiled) directly by a lubricant discharge 378 (shown in dashed-line format) from lubricant held in the reservoir 190 by adding an appropriately placed through-hole through the reservoir structure 192. In the illustrated example, such a through-hole can be positioned to substantially lie along the dashed-line of the discharge 378.

[0095] In a still further implementation, it should be appreciated that the wheel bearings associated with the axle shaft 20 can lubricated (oiled) by a lubricant discharge 386 (shown in dashed-line format) from lubricant held in the reservoir 190 by adding an appropriately placed through-hole through the reservoir structure 192. In the illustrated example, such a through-hole can be positioned to substantially lie along the dashed-line of the discharge 386. The discharge 386 drips onto the axle shaft 20 to oil the wheel bearings on the illustrated side of the electric drive unit 10.

[0096] Figure 28 is a section view of the reservoir 190, the transmission 18, and the other one of the axle shafts 20 on a second side of the electric driveunit 10 opposite the first side shown in Figure 27. in the illustrated example, a lubricant discharge 392 can be established to drip on the axle shaft 20 to lubricate the wheel bearings. The discharge 392 can be established by adding a port 394 having an outlet in the carrier housing 36 that is positioned as shown above the axle shaft 20, wherein the port 394 has an inlet extending through the second housing member 42 to access lubricant from one of the gear shaft bearings (an exemplary access point 396 is shown in dashed-line format in Fig. 2).

[0097] Figure 29 is a section view of a portion of the differential assembly 16 and the transmission 18 depicting a further lubrication implementation, similar to that shown in Figure 20. The gear shaft feed orifice 358 is configured to lubricate the bearings 360 on a gear shaft such as an idler gear shaft 364 as shown. In addition, it should be appreciated that a bearing 388 can be lubricated (oiled) by a lubricant discharge 390 (shown in dashed-line format) by adding (e.g., by drilling) an appropriately placed through-hole through the gear shaft ( / .e., the idler gear shaft as shown) in line with the bearing 388. The centrifugal force can expel lubricant and direct lubricant to the bearing 388.

[0098] It should be understood that because in some implementations some lubricant from the second portion 188 of the lubricant that flows through and exits the stator assembly 62 will be used for lubrication instead of being directly returned to the reservoir, not all of the lubricant initially directed through the stator cooling channels 294 will be directly returned to the reservoir 190 via port 380.

[0099] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustiveor to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

CLAIMSWhat is claimed is:

1. An electric drive unit, comprising: a carrier housing having a gearbox cavity that includes a sump; a motor assembly having a motor housing fixedly coupled to the carrier housing and an electric motor received in the motor housing having a stator assembly and a rotor assembly rotatable about a motor axis, the motor assembly further including a motor controller in the motor housing configured to control a rotational speed of the rotor assembly and an inverter wherein the inverter has an inverter mount, an outlet port, and a flow guide, the inverter mount defines an inlet that is fluidly coupled to the outlet port, the inverter further including a plurality of power semiconductors each having a respective heat sink thermally coupled thereto, the inverter mount and the flow guide defining a chamber in which the heat sinks reside, the outlet port being fluidly coupled to the rotor assembly; a reservoir coupled to one of the carrier housing or the motor housing; and a lubrication and cooling system coupled to the sump and the reservoir and configured to produce a flow of lubricant to the chamber and through the heat sinks therein, wherein a first portion of the lubricant flow exiting the chamber passes through the inlet to and through the rotor assembly via passing through the outlet port wherein the first portion is discharged from the rotor assembly and drains to the sump, and wherein a second portion of the lubricant flow exiting from the chamber passes through the flow guide towards and through the stator assembly, lubricant from the second portion being directlyreturned to the reservoir, and wherein the second portion is greater than the first portion.

2. The electric drive unit of claim 1 wherein the reservoir is spaced apart and elevated relative to the sump.

3. The electric drive unit of claim 1 wherein the stator assembly includes a stator core and a stator sleeve assembly configured to seal the rotor assembly from the stator core, the inverter mount further including an end plate, an outer annular wall, and an annular inner wall, wherein the inlet is disposed between the stator sleeve assembly and the annular inner wall.

4. The electric drive unit of claim 3 wherein the rotor assembly includes a rotor including a rotor lamination stack having a plurality of laminations and a rotor output shaft coupled to the laminations, the rotor output shaft defining a hollow cavity open on a first axial end and closed on a second axial end opposite the first axial end, the rotor shaft having a rotor coolant return passage extending between the second axial end and the first axial end, wherein the first portion of lubricant flow from the outlet port passes into the hollow cavity of the rotor shaft at the first axial end and is directed radially outwardly at the second axial end of the hollow cavity into the rotor coolant return passage and is discharged via the opening at the first axial end to drain into the sump.

5. The electric drive unit of claim 4 further comprising a rotor end cap configured to close the second axial end of the rotor output shaft, the end cap having a return cavity in fluid communication with the hollow cavity of the rotor output shaft configured to reverse flow of lubricant and to direct lubricant to flow into and through the rotor coolant return passage.

6. The electric drive unit of claim 1 wherein the flow guide comprises a plurality of flow openings through which the second portion of the lubricant flow passes towards the stator assembly.

7. The electric drive unit of claim 6 wherein the stator core includes stator cooling channels formed longitudinally through the stator core, wherein the second portion of the lubricant flow passes through the stator cooling channels.

8. The electric drive unit of claim 7 wherein the carrier housing includes a recess confronting the stator cooling passages into which the second portion of the lubricating fluid exits, the recess having a circumferential sidewall extending from a surface, the recess including a return port of a reservoir return conduit that fluidly couples the recess to the reservoir.

9. The electric drive unit of claim 8 wherein the transmission includes a transmission shaft configured to rotate on a bearing, the recess further including a gear shaft feed orifice extending through the surface to thegearbox cavity to permit lubricant to flow from the recess to the gearbox cavity to lubricate the bearing.

10. The electric drive unit of claim 8 wherein the transmission includes a pair of gears in mesh, the recess further including a gear mesh lubrication aperture extending between the surface and the gearbox cavity to permit lubricant to flow from the recess to the gearbox cavity to lubricate the gears in mesh.

11. The electric drive unit of claim 7 wherein the motor assembly extends axially along the motor axis between a proximal end having the motor controller and a distal end where the rotor output shaft includes an input pinion, the first portion of the lubricant flow through the rotor assembly passes through the hollow cavity from the distal end towards the proximal end and through the rotor coolant return passage from the proximal end to the distal end, and wherein the second portion of the lubricant flow through the stator assembly passes through the stator coolant passages from the proximal end to the distal end.

12. The electric drive unit of claim 3 wherein a first configuration of the flow openings relative to a second configuration of the inlet determines the respective lubricant flow volumes corresponding to the first portion and the second portion.13 The electric drive unit of claim 12 wherein the first portion is about one-third of the lubricant flow exiting the chamber and the second portion is about two-thirds of the lubricant flow exiting the chamber.

14. The electric drive unit of claim 12 wherein the first configuration of the flow openings in respect of size relative to the second configuration in respect of size of the inlet is such that the second portion is greater than the first portion.

15. The electric drive unit of claim 1 wherein the first portion of lubricant passing through the rotor assembly and to the sump constitutes a first coolant flow path and the second portion of lubricant passing through the stator assembly and to the reservoir constitutes a second coolant flow path.

16. The electric drive unit of claim 1 , wherein the reservoir is spaced apart and elevated from the sump, the lubrication and cooling system including a scavenge pump, a main pump, a heat exchanger, and a filter base, wherein the main pump has a main inlet coupled to the reservoir and is configured to draw lubricant from the reservoir, the main pump has a main outlet configured to transmit lubricant to the heat exchanger wherein lubricant from the heat exchanger flows through a filter mounted to the filter base and outputs filtered lubricant to the inverter, and wherein the scavenge pump has a scavenge inlet coupled to the sump and is configured to draw lubricant from the sump, the scavenge pump has a scavenge outlet configured transmit lubricant to the reservoir.

17. The electric drive unit of claim 1 wherein the motor housing defines a motor cavity and wherein the rotor assembly, the stator assembly, and the motor controller are received in the motor cavity.

18. The electric drive unit of claim 1 further comprising a differential assembly received in the gearbox cavity, the differential assembly having a differential input member, which is rotatable about an output axis, and a differential gearset having first and second differential output members; and a transmission received in the gearbox cavity transmitting rotary power between the motor assembly and the differential assembly, the differential input member being driven by an output of the transmission.

19. The electric drive unit of claim 9 further including a first axle shaft received through the carrier housing coupled to the first differential output member for rotation therewith; and a second axle shaft received through the carrier housing coupled to the second differential output member for rotation therewith.

20. An electric drive unit, comprising: a carrier housing having a gearbox cavity that includes a sump; a motor assembly having a motor housing fixedly coupled to the carrier housing and an electric motor received in the motor housing having a stator assembly and a rotor assembly rotatable about a motor axis, the motorassembly further including a motor controller received in the motor housing configured to control a rotational speed of the rotor assembly and an inverter, the inverter includes an inverter mount defining an inlet therein and a flow guide wherein the inlet is fluidly coupled to an outlet port, the inverter further including a plurality of power semiconductors each having a respective heat sink thermally coupled thereto, the inverter mount and the flow guide defining a chamber in which the heat sinks reside, the outlet port being fluidly coupled to the rotor assembly; a reservoir coupled to the carrier housing and is separate from and elevated relative to the sump; and a lubrication and cooling system coupled to the sump and the reservoir configured to produce a flow of lubricant to the chamber and through the heat sinks therein, wherein a first portion of the lubricant flow exiting the chamber passes through the inlet through the rotor assembly via the outlet port to be discharged from the rotor assembly to drain to the sump, and wherein the flow guide directs a second portion of the lubricant flow exiting the chamber towards and through the stator assembly, lubricant from the second portion being directly returned to the reservoir, wherein the flow guide comprises a plurality of flow openings through which the second portion of the lubricant flow passes and the flow openings are configured in size relative to the size of the inlet such that the second portion is greater than the first portion.

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