Drive unit for electric vehicle

Drive units for electric vehicles are provided. One example provides a drive unit for an electric vehicle including a first housing section forming a first compartment to house an electrical inverter and a second housing section forming a second compartment to house an electric motor. The drive unit housing further includes an inlet port to receive a fluid and a shared wall separating the first compartment and the second compartment. The shared wall defines fluid pathways in fluid communication with the inlet port to circulate the fluid to cool the electrical inverter. The drive unit also includes an outlet port in fluid communication with the fluid pathways to discharge the fluid.

TECHNICAL FIELD

The present disclosure relates generally to electric vehicles and, in particular embodiments, to powertrain components of electric vehicles.

BACKGROUND

Electric powertrains of electric vehicles, including electric powersport vehicles (e.g., all-terrain vehicles (ATVs), personal watercraft (PWC), and snowmobiles), typically include a battery system, one or more electrical motors, each with a corresponding electronic power inverter (sometimes referred to as a motor controller), and various auxiliary systems (e.g., cooling systems). Efficiencies in size, weight, and energy consumption of system components improve vehicle performance (e.g., responsiveness, range, and reliability) and cost, particularly for electric powersport vehicles where space and weight are at a premium.

SUMMARY

Some embodiments of the present disclosure relate to a drive unit housing that houses both an electrical inverter and an electric motor. Optionally, the drive unit housing may include a shared wall the separates the electrical inverter and the electric motor into different compartments. Advantageously, the drive unit housing may provide space-efficient packaging for the electrical inverter and electric motor, and may also improve performance by reducing the length of electrical connections between the electrical inverter and electric motor.

One example provides a drive unit for an electric vehicle including a housing having a first compartment and a second compartment separated from one another by a shared wall, an electrical inverter disposed within the first compartment and having a set of electrical output terminals, and an electric motor disposed within the second compartment and having electrical input terminals electrically coupled to the output terminals via one or more openings extending through the shared wall.

According to one example of the present disclosure, a drive unit for an electric vehicle is provided. The drive unit includes a housing having a first compartment and a second compartment separated from one another by a shared wall. The drive unit also includes an electrical inverter disposed within the first compartment and having a set of electrical output terminals, and an electric motor disposed within the second compartment and having electrical input terminals electrically coupled to the output terminals via one or more openings extending through the shared wall.

In some examples, the input terminals of the electric motor include electrical leads extending through the one or more openings into the first compartment.

In some examples, a perimeter of the housing is confined within a generally longitudinal form factor, the first and second compartments being disposed axially to one another along a longitudinal axis of the longitudinal form factor. The longitudinal form factor may be generally cylindrical in shape. The electrical inverter may include a set of solid-state switches providing electrical power to the electrical output terminals, the switches and output terminals disposed within the first compartment such that the set of output terminals axially aligns with the electrical input terminals of the electric motor to reduce conductor lengths between the electric motor and the set of solid-state switches. Optionally, the electrical output terminals are arrayed along an arc to axially align with the electrical input terminals. The electrical inverter may also or instead include a set of capacitors to receive DC power from a battery source, the capacitors offset in a radial direction of the longitudinal form factor from the set of solid-state switches.

According to one example, a drive unit housing for an electric vehicle is provided. The housing includes a first housing section defining a first compartment to house an electrical inverter and a second housing section defining a second compartment to house an electric motor. The first and second housing sections are separably coupled to one another with the first and second compartments separated by a shared wall.

In some examples, perimeters of the first and second housing sections are confined within a generally longitudinal form factor with the first and second housing sections being disposed axially to one another along a longitudinal axis of the longitudinal form factor. The longitudinal axis of the longitudinal form factor may be aligned with an axis of a rotor shaft of the electric motor when disposed within the second compartment.

In some examples, the first housing section includes a substantially tubular perimeter casing defining a circumference of the first compartment and having first and second open ends. The shared wall may be coupled to and closing the first open end. The first housing section may also or instead include a cover plate separably coupled to the tubular perimeter casing to cover the second open end. Optionally, the shared wall and the tubular perimeter casing comprise a contiguous, integrated piece. The cover plate may include electrical terminals for connection to the electrical inverter from a battery system.

In some examples, the second housing section includes a substantially tubular perimeter casing defining a circumference of the second compartment and having first and second open ends and a cover plate coupled to and closing the first end. Optionally, the shared wall closes the second end when the tubular perimeter casing is coupled thereto.

In some examples, the shared wall includes a bearing pocket on a side facing the second compartment to receive an end of a rotor shaft of the electric motor.

In some examples, the first compartment includes a first compartment portion to house capacitors of the electrical inverter and a second compartment portion to house power switching and control electronics of the electrical inverter.

In some examples, the shared wall includes one or more openings extending there through to provide electrical connection of the electric motor to the electrical inverter. Electrical power leads from a stator of the electric motor may pass through the one or more openings from the second compartment to the first compartment.

According to one example of the present disclosure, an electric vehicle is provided. The electric vehicle includes a battery system, an electrical inverter electrically coupled to the battery system, an electric motor, electrically coupled to the power inverter, to propel the electric vehicle, and a housing having a first compartment to house the power inverter and a second compartment to house the electric motor, the first compartment and second compartment being separated by a shared wall.

Some embodiments of the present disclosure provide a drive unit defining fluid pathways to circulate a fluid to cool an electrical inverter and/or an electric motor. The fluid pathways may be integrally formed within the drive unit, such that they do not extend outside of a perimeter of the drive unit. For example, the fluid pathways may be formed in a shared wall separating different compartments of the drive unit, in outer sidewalls of a housing of the drive unit and/or in a rotor shaft of the electric motor. In this way, the fluid pathways may efficiently cool the drive unit without significantly increasing its overall footprint.

One example provides a drive unit housing for an electric vehicle including a first housing section having perimeter sidewalls forming a first compartment to house an electrical inverter, and a second housing section having perimeter sidewalls forming a second compartment to house an electric motor. The first compartment is separated from the second compartment by a shared wall, the shared wall including fluid pathways to circulate fluid to cool the electrical inverter and the perimeter sidewalls of the second housing section including fluid pathways to circulate fluid to cool the electric motor.

According to one example, a drive unit housing for an electric vehicle is provided. The housing includes a first housing section forming a first compartment to house an electrical inverter, a second housing section forming a second compartment to house an electric motor, an inlet port to receive a fluid, a shared wall separating the first compartment and the second compartment, the shared wall defining fluid pathways in fluid communication with the inlet port to circulate the fluid to cool the electrical inverter, and an outlet port in fluid communication with the fluid pathways to discharge the fluid.

In some examples, the fluid pathways of the shared wall are first fluid pathways, and the second housing section includes perimeter sidewalls defining second fluid pathways in fluid communication with the inlet port to circulate the fluid to cool the electric motor. The first fluid pathways of the shared wall may be disposed in series with the second fluid pathways of the perimeter sidewalls of the second housing section between the inlet port and the outlet port. Optionally, the first fluid pathways and the second fluid pathways may form a continuous fluid pathway between the inlet port and the outlet port. The continuous fluid pathway may be contained within a longitudinal form factor defined by a perimeter of the drive unit housing.

In some examples, the perimeter sidewalls of the second housing section include a cylindrical housing extending about a perimeter of a stator of the electric motor, the second fluid pathways extending about a circumference of the cylindrical housing. The second fluid pathways may extend in a spiral about the circumference of the cylindrical housing.

In some examples, the electric motor includes a hollow rotor shaft defining third fluid pathways in fluid communication with the input port to circulate the fluid to cool the electric motor. The first fluid pathways of the shared wall and the second fluid pathways of the perimeter sidewalls may be disposed in series with the third fluid pathways of the hollow rotor shaft. Optionally, the first fluid pathways, the second fluid pathways and the third fluid pathways form a continuous fluid pathway between the inlet port and the outlet port.

In some examples, the shared wall defines a bearing pocket in which an end of the hollow rotor shaft is disposed. The shared wall may include a tube extending from the bearing pocket to be received within the end of the hollow rotor shaft, the tube and the end of the hollow rotor shaft forming at least part of the third fluid pathways.

In some examples, a perimeter of the drive unit housing is confined within a generally longitudinal form factor, the first and second compartments being disposed axially to one another along a longitudinal axis of the longitudinal form factor. The longitudinal form factor may be generally cylindrical in shape and/or the shared wall may be generally circular in shape. The inlet port and the outlet port being confined within the generally longitudinal form factor. For example, the first housing section may define a first recess in which the inlet port is disposed and/or define a second recess in which the outlet port is disposed.

In some examples, the electrical inverter includes a capacitor mounted to the shared wall, the fluid pathways arranged so as to first pass the capacitor downstream of the inlet port.

In some examples, the first housing section is separable from the second housing section.

According to one example of the present disclosure, the is provided a drive unit for an electric vehicle. The drive unit includes an electrical inverter, an electric motor electrically coupled to the electrical inverter, and a housing. The housing includes a first housing section having perimeter sidewalls forming a first compartment to house the electrical inverter, a second housing section having perimeter sidewalls forming a second compartment to house the electric motor, the first and second compartments separated from one another by a shared wall, and a continuous fluid pathway extending through the first and second housing sections to circulate fluid to cool the electrical inverter and the electric motor.

According to one example of the present disclosure, there is provided a method of cooling a drive unit for an electric vehicle. The drive unit may include an electrical inverter, an electric motor and a housing in which the electrical inverter and the electric motor are disposed. The method includes receiving a fluid via an inlet port of the housing, circulating the fluid through fluid pathways formed in a shared wall of the housing to cool the electrical inverter, the shared wall separating a first compartment of the housing in which the electrical inverter is disposed and a second compartment of the housing in which the electric motor is disposed, and discharging the fluid via an outlet port of the housing.

In some examples, the fluid pathways are first fluid pathways, the method including circulating the fluid through second fluid pathways formed in a perimeter sidewall of the housing to cool the electric motor.

Additional and/or alternative features and aspects of examples of the present technology will become apparent from the following description and the accompanying drawings.

DETAILED DESCRIPTION

Electric powertrains for electric vehicles, including electric powersport vehicles (e.g., motorcycles, all-terrain vehicles (ATVs), personal watercraft (PWC), (e.g., side-by-side) utility task vehicles (UTVs) and snowmobiles), typically include a battery system, one or more electrical motors, each with a corresponding electronic power inverter (sometimes referred to as a motor controller), and various auxiliary systems (e.g., cooling systems). Efficiencies in size, weight, and energy consumption of system components improve vehicle performance (e.g., responsiveness, range, and reliability) and cost, particularly for electric powersport vehicles where space and weight are at a premium.

FIG.1generally illustrates an electric vehicle10including an electric drive unit30, in accordance with examples of the present disclosure. Although illustrated as a snowmobile for example purposes, electric vehicle10could be other types of electric vehicles, including other types of powersport vehicles such as personal watercraft (PWC) and side-by-side vehicles. Electric vehicle10includes a seat11, which is shown as a straddle-seat, to accommodate an operator of electric vehicle10. Electric vehicle10employs an electric powertrain12including a battery system14, an electric motor16, and an electronic power inverter18for controlling electric motor16. Powertrain12is configured to propel the electric vehicle by driving one or more wheels (e.g., in the case of a motorcycle, ATV or UTV), by driving an endless track (e.g., in the case of a snowmobile) or by driving a propeller or impeller (e.g., in the case of a PWC).

In some examples, electric motor16may be a permanent magnet synchronous motor. Electric motor16may have a power output of between 120 and 180 horsepower. Alternatively, electric motor16may have a maximum output power of greater than 180 horsepower. In some examples, battery system14may include a rechargeable multi-cell lithium ion or other type of battery. Battery system14may include multiple battery modules each including multiple battery cells. The battery cells may be pouch cells, cylindrical cells and/or prismatic cells, for example. The battery modules may be housed within a battery enclosure for protection from impacts, water and/or debris. In some examples, battery system14may be configured to output electric power at a voltage of between 300-400 volts, or up to 800 volts, for example.

According to one example of the present disclosure, as will be described in greater detail herein, drive unit30includes a housing having a first compartment22and a second compartment24separated from one another by a shared wall26. In one example, as illustrated, inverter18is disposed in first compartment22and motor16is disposed in second compartment24. Together, housing20with motor16and inverter18disposed therein form drive unit30for electric vehicle10.

As will be described in greater detail below, by disposing motor16and inverter18together within housing20, drive unit30provides a volumetrically efficient form factor (e.g., a generally longitudinal form factor, such as a cylindrical form factor, for instance) which consumes less space within electric vehicle10. Additionally, drive unit30provides shortened electrical conductor lengths between output terminal of inverter18and input terminals of motor16which reduces electrical inductance and line losses (relative to separately housed motor-inverter combinations). Accordingly, drive unit30, in accordance with the present disclosure, provides efficiencies in both space and performance relative to conventional, separately housed motor-inverter combinations.

FIG.2is a block and schematic diagram generally illustrating one example of electric vehicle10, where, in addition to including electric powertrain12employing drive unit30, electric vehicle10further includes a thermal management system32. In one example, thermal management system32manages the temperatures (e.g., cooling) of electric powertrain12components, including battery system14, motor16, and inverter18. Thermal management system32may be a closed-loop cooling system and/or an open-loop cooling system. The thermal management system32may utilize a liquid-to-liquid cooling system (e.g., in the case of a PWC), a snow-to-liquid cooling system (e.g., in the case of a snowmobile), an air-to-liquid cooling system (e.g., using a radiator), or a combination thereof. In accordance with examples of the present disclosure, as will be described in greater detail below, housing20of drive unit30includes a network of fluid circulation pathways34through which the thermal transfer fluid is circulated, as indicated arrows36, to manage the temperatures of motor16and inverter18.

FIGS.3A-3Cillustrate perspective views of drive unit30, according to examples of the present disclosure.FIG.4is an exploded view illustrating portions of drive unit30, according to one example. In some examples, housing20includes a first housing section40forming a first compartment22for housing inverter18, and a second housing section42forming a second compartment24for housing electric motor16. First and second housing sections40and42may each include at least some walls or other structural components of housing20. While first and second housing sections40and42form first and second compartments22and24, respectively, first and second housing sections40and42might not fully enclose first and second compartments22and24.

In one example, a perimeter of housing20is confined within a generally longitudinal form factor44(graphically represented by dashed lines inFIG.3A), where first and second housing sections40and42, respectively forming first and second compartments22and24, are disposed longitudinally relative to one another within the form factor. In one example, as illustrated, form factor44is generally cylindrical in shape with first and second housing sections40and42being disposed longitudinally relative to one another along a longitudinal axis48of generally cylindrical form factor44. Shared wall26is generally circular in shape. In one example, longitudinal axis48of form factor44generally coincides with a longitudinal axis of a shaft46(i.e., a rotor shaft) of motor16(which extends from second housing section42). In examples, as described below, first and second housing sections40and42are separable from one another.

In one example, first housing section40includes shared wall26, which provides a base for first housing section40and which is disposed transversely to longitudinal axis48of form factor44. Shared wall26may be integrally formed with first housing section40. In one example, shared wall26is substantially circular in shape, but any suitable shape may be employed. First housing section40further includes a perimeter sidewall casing50. In one example, as illustrated, perimeter sidewall casing50is ring- or band-shaped to form a generally tubular or circumferentially extending perimeter sidewall. In one example, the ring- or band-shaped perimeter sidewall casing50may be formed of a partial or continuous curved wall section, or may be formed from multiple straight wall sections extending from shared wall26that together form the ring- or band-shaped sidewall casing50. In one example, perimeter sidewall casing50extends orthogonally from shared wall26and longitudinally relative to form factor44, where shared wall26and circumferentially extending sidewall50together are generally can- or cup-shaped to form first compartment22for housing inverter18. An end cover52is separably coupled to sidewall casing50to enclose first compartment22.

In one example, second housing section42includes a perimeter sidewall casing54separably coupled to shared wall26, such as via a number of fasteners55(e.g., screws or bolts) arranged about perimeter sidewall casing50of first housing section40. In one example, perimeter sidewall casing54is ring- or tube-shaped to form a generally tubular or circumferentially extending perimeter sidewall. In one example, perimeter sidewall casing54extends orthogonally from shared wall26and longitudinally relative to form factor44with shared wall26serving as a base for second housing section42, and with shared wall26and perimeter sidewall casing54together being drum-shaped to form second compartment24for housing motor16. An end cover56is separably coupled to an end of perimeter sidewall casing54opposite shared wall26to enclose second compartment24. Alternatively, end cover56may be integrally formed with sidewall casing54of the second housing section42, such that the shared wall26acts as an endplate for enclosing the second compartment24.

While shared wall26is described as being part of first housing section40, in other examples, shared wall26may be part of second housing section42. In other examples, shared wall26may be separable from both first and second housing sections40and42.

In one example, end cover52includes positive and negative DC connection terminals60and62extending there through for electrical connection of capacitors of inverter18(see120inFIG.7) to battery system14(seeFIGS.1and2). In one example, end cover52includes an electrical connector64for low voltage and control signal connection to control circuitry of inverter18(see124inFIG.7).

In one example, as will be described in greater detail below, first housing section40respectively includes inlet and outlet fluid ports66and68(seeFIG.3B-3C) for connecting fluid pathways of thermal management system32to fluid pathways within housing20of drive unit30for cooling of motor16and inverter18. Inlet66may receive a fluid from thermal management system32, and outlet68may discharge the fluid back into thermal management system32. It is noted that in other examples, inlet and outlet fluid ports66and68may be reversed, and that in other examples, more than one inlet and/or outlet port may be employed. In one example, as illustrated, sidewall casing50includes recesses70and72in which inlet and outlet fluid ports66and68are respectively disposed so that inlet and outlet fluid ports66and68are disposed within the confines of form factor44.

In one example, as illustrated byFIG.3A, a number of channels73extend circumferentially about sidewall casing54of second housing section42. When a casing sleeve75is disposed about the circumference of sidewall casing54, channels73become fluid pathways74(seeFIG.6) extending about the circumference of second housing section42, where such fluid pathways74are part of the network of fluid pathways34through which fluid36is circulated by thermal management system32(seeFIG.2) to cool motor16. In some examples, fluid pathways74may form a continuous spiral around sidewall casing54. In other examples, fluid pathways74may be separate pathways disposed in parallel with one another. In other examples, fluid pathways74may be a continuous pathway employing a switchback configuration. Any number of suitable implementations may be employed.

Reference is now made toFIG.4, which illustrates end cover52being removed from sidewall casing50of first housing section40, and showing first and second housing compartments22and24. Motor16includes a rotor76and a stator78which are disposed within second compartment24of second housing section42. As will be described in greater detail below (seeFIG.9), an end80of shaft46facing shared wall26is hollow to enable circulation of thermal transfer fluid there through to cool motor16. A set of electrical input leads84extend from stator78for connection to inverter18within compartment22of first housing section40.

In one example, first compartment22of first housing section40includes a first compartment portion90for housing capacitors of inverter18, and a second compartment portion92for housing electronic control and switching components (e.g., insulated-gate bipolar transistors (IGBTs)) of inverter18(see122and124inFIG.7). In one example, a set of one or more openings94extend through shared wall26to enable electrical connection between input leads84of stator78and output terminals of inverter18. In one example, input leads84from stator78extend through openings94into second compartment portion92for connection to output terminals of inverter18. In other examples, output terminals of inverter18may extend through openings94into second housing section42for connection to input leads84of stator78.

FIG.5is a perspective view illustrating first housing section40with end cover52removed. In one example, input power leads84of stator78extend through the set of openings94in shared wall26and terminate at a set of terminals96(illustrated as terminals96a,96b, and96c) in second compartment portion92. Sensor wiring98extends from motor16through shared wall26to inverter control electronics. By aligning the set of openings94through shared wall26(see alsoFIG.8) with input leads84of stator78and with terminals96, the lengths of conductor pathways between inverter18and stator78are reduced which, in-turn, reduces electrical inductances and power loss, thereby improving the electrical efficiency of drive unit30.

As discussed in further detail elsewhere herein, housing20includes a network of fluid pathways34(also referred to as a fluid network) extending therethrough for cooling of motor16and inverter18. In one example, in addition to inlet and outlet ports66and68, fluid network34includes a fluid chamber100in shared wall26having a fluid inlet102and a fluid outlet104connecting fluid chamber100with other portions of the fluid network34. It is noted that a cover over fluid chamber100is not shown inFIG.5. In one example, a network of power switches (e.g., IGBTs) is mounted to shared wall26over fluid chamber100so as to be cooled by fluid circulated there through.

FIG.6is a cross-sectional view of housing20, according to one example, where sidewall casing50of first housing section40contiguously and integrally extends from shared wall26, and which together with end cover52forms first compartment22. First compartment22includes first compartment portion90for housing capacitors of inverter18, and second compartment portion92for housing control and switching electronics of inverter18. In one example, shared wall26includes a bearing pocket110facing second compartment24, where bearing pocket110is to receive end80of shaft46of electric motor16and through which thermal transfer fluid circulates, as described below.

Sidewall casing54and end cover56of second housing section42together with shared wall26form second compartment24. End cover56includes a bearing pocket112to receive an opposing end of shaft46of motor16and an aperture114from which shaft46extends. Gaskets116and118respectively form seals between shared wall26and sidewall casing54to seal second compartment24, and between end cover52and sidewall casing50to seal first compartment22.

FIG.7is a cross-sectional view of drive unit30, according to one example. DC capacitors120of inverter18are disposed in first compartment portion90, while power switching network122and control electronics124of inverter18are disposed in second compartment portion92. Input power leads84from stator78of motor16extend through shared wall26and terminate at terminals96in second compartment portion92. Motor16is disposed within second compartment24with hollow end80of shaft46disposed within bearing pocket110of shared wall26.

FIG.8is a perspective view illustrating portions of first housing section40facing second (motor) compartment24including shared wall26and sidewall casing50, according to one example. In one example, as illustrated, sidewall casing50contiguously extends from shared wall26such that shared wall26and sidewall casing50form a single base component for first housing section40. A plurality of ribs, such as rib130, extend from an inner surface of sidewall casing50to support a central hub132including bearing pocket110for supporting hollow end80of shaft46of motor16. Also illustrated is the set of openings94through shared wall26, illustrated as openings94a-94carrayed along an arc to align with input leads84of stator78(seeFIG.4). While three openings94a-94care shown in the Figures, this is exemplary only. In one example, shared wall26may include a single opening94for input leads84and terminals96, or any other suitable number of openings94.

In one example, end wall26includes a portion of the network of fluid pathways34through which a thermal transfer fluid is circulated to cool components of motor16and inverter18. The network34of fluid pathways, which will be described in greater detail below (seeFIG.10) includes inlet and outlet ports66and68, as well as fluid chamber100having inlet and outlet102and104(seeFIG.5). In one example, network34further includes a tube134which extends within hub132and, as will be described below (seeFIG.9), extends into hollow end80of shaft46to form inlet and outlet fluid pathways within shaft46to enable circulation of thermal transfer fluid therein to cool motor16.

FIG.9is a schematic diagram generally illustrating the circulation of thermal transfer fluid within hollow end80of shaft46. As illustrated, tube134extends into hollow end80of shaft46from bearing pocket110(disposed within hub132) to form an inlet fluid pathway136within tube134, and an outlet fluid pathway138between the outer wall of tube134and inner wall of shaft46. In this way, tube134and hollow end80of shaft46form fluid pathways in shaft46. In one example, inlet and outlet fluid pathways136and138are respectively in fluid communication with fluid pathways140and142of the network of fluid pathways34(seeFIG.10below).

FIGS.10A and10Bare perspective views illustrating portions of network34of fluid pathways, according to one example, for circulating thermal transfer fluid through housing20to cool components of motor16and inverter18.FIGS.10A and10Billustrate network34as respectively viewed from second (motor) compartment24and first (inverter) compartment22.

In one example, as illustrated, thermal transfer fluid is received via inlet port66and travels through pathways140to inlet fluid pathway136within tube134inside shaft46(seeFIG.9). Fluid then travels through outlet fluid pathway138and exits shaft46via fluid pathway142, which is concentrically disposed about end80of shaft46. Fluid then travels through a fluid pathway144, which forms a fan-like, semicircular path along or within shared wall26proximate to first compartment portion90of first compartment22to cool DC capacitors120of inverter18(seeFIG.7).

Fluid then enters chamber100via inlet opening102, where fluid within chamber100cools the power switching network122and control electronics124of inverter18disposed within second compartment portion92of first compartment22(seeFIG.7). Fluid then exits chamber100via outlet opening104and travels through a fluid pathway146to fluid pathways74circumferentially disposed about sidewall casing54of second housing section42to cool motor16(see, for example,FIGS.3A and7). Fluid then exits fluid pathways74to outlet port68.

In one example, the fluid pathways of network34of fluid pathways forms a continuous fluid pathway through housing20such that the components of drive unit30are cooled in series (e.g., shaft46, capacitors120, power switching network122, and motor stator78). In one example, the fluid pathways of shared wall26are disposed in series with the fluid pathways of perimeter sidewall54of second housing section42between inlet and outlet ports66and68. In one example, the fluid pathways of shared wall26and perimeter sidewall54of second housing section42are disposed in series with fluid pathways within hollow end80of shaft46of electric motor16.

By employing a single continuous cooling loop, the cooling system is simplified (relative to systems employing parallel pathways), such that the network of fluid pathways34of the present disclosure provides high efficiency and requires fewer parts relative to known systems. Additionally, disposing the network of fluid pathways34within the confines of housing20(i.e., within form factor44), including disposing inlet and outlet ports66and68on end cover52of first housing section40maintains the perimeter of drive unit30within the generally longitudinally extending form factor44(seeFIG.3A). As described above, such form factor is volumetrically efficient and provides improved ease of installation within electric vehicles (particularly electric powersport vehicles).

It is noted that the network of fluid pathways34specifically described herein is for illustrative purposes, and represents only one example implementation of fluid network34. In the example shown, the fluid pathways34travel from an inlet port66, to the shaft46, to the channels within the shared wall26, to the circumferentially disposed pathways74in the sidewall casing54, and finally to the outlet port68. In other examples, the configuration of the fluid pathways of fluid network34and the order in which components are cooled may be different from that illustrated herein. In another example, the fluid pathways34may travel from an inlet port66, to the channels within the shared wall26, to the shaft46, to the circumferentially disposed pathways74in the sidewall casing54, such that the inverter18components are cooled prior to the motor components. For example, fluid network34may be implemented such that thermal transfer fluid is first directed to cool DC capacitors120of inverter18, as such capacitors may have a narrow thermal tolerance. Any number of configurations are possible. Further, one or more pathways in the network of fluid pathways may be omitted in some examples. For example, a network of fluid pathways may omit fluid pathways in shaft46. The fluid pathways may travel from an inlet port66, to the channels within the shared wall26, to the circumferentially disposed pathways74in the sidewall casing54, and finally to the outlet port68.

Housing20may be made, in whole or in part, from metals, metal alloys, composites and/or plastics. Similarly, the channels/pathways of fluid network34may be made, in whole or in part, from metals, metal alloys, composites and/or plastics. It is further noted that the components of housing20, including the channels/pathways of fluid network34may be manufactured according to any know technique, including machining, casting, and 3D-printing, for example.

In one example, the form factor44of the housing20of the drive unit30that is suitable for a powersport vehicle10may have a length of 10 cm to 30 cm and a diameter or width of 20 cm to 30 cm. In one example, the thickness of the shared wall26may be between 3 mm and 8 mm, which provides a sufficient thickness to accommodate channel144and chamber100. It should be understood that the form factor44and shared wall26thickness may have any suitable dimensions, and that these dimensions may vary depending on the application and power requirements of the drive unit30.

FIG.11is a flow diagram illustrating a method200for cooling components of a drive unit, according to one example of the present disclosure. The method200may be performed by a drive unit housing such as housing20, for example. Block202includes receiving a fluid via an inlet port of the housing. For example, block202may include inlet66receiving a fluid. Block204includes circulating the fluid. In some examples, the fluid is circulated through fluid pathways formed in the housing to cool an electrical inverter and/or an electrical motor. For example, block204may include circulating the fluid through fluid pathways formed in a shared wall (e.g., shared wall26) of the housing to cool the electrical inverter. The shared wall may separate a first compartment of the housing in which the electrical inverter is disposed and a second compartment of the housing in which the electric motor is disposed. Alternatively or additionally, block204may include circulating the fluid through fluid pathways formed in a perimeter sidewall of the housing (e.g., perimeter sidewall casing54) to cool the electric motor. Alternatively or additionally, block204may include circulating the fluid through fluid pathways formed in a rotor shaft (e.g., shaft46) of the electric motor to cool the electric motor. Block206includes discharging the fluid via an outlet port of the housing, such as outlet port68, for example.

Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.

Example embodiments of the present disclosure will now be provided.

Example embodiment 1: A drive unit for an electric vehicle comprising:a housing having a first compartment and a second compartment separated from one another by a shared wall; an electrical inverter disposed within the first compartment and having a set of electrical output terminals; an electric motor disposed within the second compartment and having electrical input terminals electrically coupled to the output terminals via one or more openings extending through the shared wall.

Example embodiment 2: The drive unit of example embodiment 1, the input terminals of the electric motor comprising electrical leads extending through the one or more openings into the first compartment.

Example embodiment 3: The drive unit of example embodiment 1, a perimeter of the housing being confined within a generally longitudinal form factor, the first and second compartments being disposed axially to one another along an axis of the longitudinal form factor.

Example embodiment 4: The drive unit of example embodiment 3, the longitudinal form factor being generally cylindrical in shape.

Example embodiment 5: The drive unit of example embodiment 1, the inverter including a set of solid-state switches providing electrical power to the electrical output terminals, the switches and output terminals disposed within the first compartment such that the set of output terminals axially aligns with the electrical input terminals of the electric motor to minimize conductor lengths between the electric motor and the set of solid-state switches.

Example embodiment 6: The drive unit of example embodiment 5, the electrical output terminals arrayed along an arc to axially align with the electrical input terminals.

Example embodiment 7: The drive unit of example embodiment 5, the inverter including a set of capacitors to receive DC power from a battery source, the capacitors laterally offset in a radial direction of the cylindrical form factor from the set of solid state switches.

Example embodiment 8: A drive unit housing for an electric vehicle comprising: a first housing section defining a first compartment to house an electrical inverter; and a second housing section defining a second compartment to house an electric motor, the first and second housing sections separably coupled to one another with the first and second compartments separated by a shared wall.

Example embodiment 9: The drive unit housing of example embodiment 8, the first housing section including the shared wall.

Example embodiment 10: The drive unit housing of example embodiment 8, wherein perimeters of the first and second housing sections are confined within a generally longitudinal form factor with the first and second housing sections being disposed axially to one another along an axis of the longitudinal form factor.

Example embodiment 11: The drive unit housing of example embodiment 10, the axis of the longitudinal form factor aligned with an axis of a rotor shaft of the electric motor when disposed within the second compartment.

Example embodiment 12: The drive unit housing of example embodiment 8, the first housing section including: a tubular perimeter casing defining a circumference of the first compartment and having first and second open ends; the shared wall coupled to and closing the first open end; and a cover plate separably coupled to the tubular perimeter casing to cover the second open end.

Example embodiment 13: The drive unit housing of example embodiment 12, the shared wall and the tubular perimeter casing comprising a contiguous piece.

Example embodiment 14: The drive unit housing of example embodiment 12, the cover plate including electrical terminals for connection to the inverter unit from a battery system.

Example embodiment 15: The drive unit housing of example embodiment 8, the second housing section including: a tubular perimeter casing defining a circumference of the second compartment and having first and second open ends; and a cover plate coupled to and closing the first end.

Example embodiment 16: The drive unit housing of example embodiment 15, the shared wall closing the second end when the tubular perimeter casing is coupled thereto.

Example embodiment 17: The drive unit housing of example embodiment 8, the shared wall including a bearing pocket on a side facing the second compartment to receive an end of a rotor shaft of the electric motor.

Example embodiment 18: The drive unit housing of example embodiment 8, the first compartment including a first compartment portion to house capacitors of the inverter and a second compartment portion to house power switching and control electronics of the inverter.

Example embodiment 19: The drive unit housing of example embodiment 8, the shared wall including one or more openings extending there through to provide electrical connection of the electric motor to the electrical inverter.

Example embodiment 20: The drive unit housing of example embodiment 19, wherein electrical power leads from a stator of the electric motor pass through the one or more openings from the second compartment to the first compartment.

Example embodiment 21: A drive unit housing for an electric vehicle comprising: a first housing section having perimeter sidewalls forming a first compartment to house an electrical inverter; and a second housing section having perimeter sidewalls forming a second compartment to house an electric motor, the first compartment separated from the second compartment by a shared wall, the shared wall including fluid pathways to circulate fluid to cool the electrical inverter and the perimeter sidewalls of the second housing section including fluid pathways to circulate fluid to cool the electric motor.

Example embodiment 22: The housing of example embodiment 21, the fluid pathways of the shared wall disposed in series with the fluid pathways of the perimeter sidewalls of the second housing section between a fluid inlet port and a fluid outlet port.

Example embodiment 23: The housing of example embodiment 22, the fluid pathways of the shared wall and perimeter sidewalls disposed in series with fluid pathways within a hollow rotor shaft of the electric motor disposed within the second housing section.

Example embodiment 24: The housing of example embodiment 21, a perimeter of the housing being confined within a generally longitudinal form factor, the first and second compartments being disposed axially to one another along an axis of the longitudinal form factor.

Example embodiment 25: The drive unit of example embodiment 24, the longitudinal form factor being generally cylindrical in shape.

Example embodiment 26: The drive unit of example embodiment 21, the first housing section including the shared wall.

Example embodiment 27: The drive unit of example embodiment 21, the first housing section separable from the second housing section.

Example embodiment 28: A drive unit for an electric vehicle comprising: a housing including: a first housing section having perimeter sidewalls forming a first compartment; and a second housing section having a perimeter sidewalls forming a second compartment, the first and second compartments separated from one another by a shared wall; an electrical inverter disposed within the first compartment, the electrical inverter including inverter components mounted to the shared wall; and an electric motor disposed within the second compartment, the shared wall including fluid pathways to circulate fluid to cool the electrical inverter and the perimeter sidewalls of the second housing section including fluid pathways to circulate fluid to cool the electric motor.

Example embodiment 29: The drive unit of example embodiment 28, the electric motor including a hollow rotor shaft having an inlet fluid pathway and an outlet fluid pathway to circulate fluid through the shaft to cool the electric motor, an end of the rotor shaft disposed within a bearing pocket on the shared wall, the inlet and outlet fluid pathways in fluidic communication with fluid pathways of the shared sidewall via the end of the rotor shaft.

Example embodiment 30: The drive unit of example embodiment 29, the fluid pathways of the shared wall, the inlet and output fluid pathways of the rotor shaft, and the fluid pathways of the perimeter sidewalls of the second housing section form a continuous fluid pathway between a fluid inlet port and a fluid outlet port.

Example embodiment 31: The drive unit of example embodiment 30, the electrical inverter including a set of capacitors mounted to the shared wall, the fluid pathways arranged so as to first pass the capacitors downstream of the fluid inlet port.

Example embodiment 32: The drive unit of example embodiment 27, the perimeter sidewalls of the second housing section including a cylindrical housing extending about a perimeter of a stator section of the electric motor, the fluid pathways extending about a circumference of the cylindrical housing.

Example embodiment 33: The drive unit of example embodiment 32, the fluid pathways extending in a spiral fashion about the circumference of the cylindrical housing.

Example embodiment 34: The drive unit of example embodiment 28, a perimeter of the housing being confined within a generally longitudinal form factor, the first and second compartments being disposed axially to one another along an axis of the longitudinal form factor.

Example embodiment 35: The drive unit of example embodiment 34, the longitudinal form factor being generally cylindrical in shape.

Example embodiment 36: A drive unit housing for an electric vehicle comprising: a first housing section having perimeter sidewalls forming a first compartment to house an electrical inverter; and a second housing section having perimeter sidewalls forming a second compartment to house an electric motor, the first compartment separated from the second compartment by a shared wall, the first and second housing sections having perimeters confined within a generally longitudinal form factor and being disposed axially to one another along an axis of the longitudinal form factor; and a continuous fluid pathway extending through the first and second housing sections between an inlet and an outlet port to circulate fluid to cool the electrical inverter and the electric motor.

Example embodiment 37: The drive unit housing of example embodiment 36, the continuous fluid pathway including a portion disposed in the shared sidewall.

Example embodiment 38: The drive unit housing of example embodiment 36, the continuous fluid pathway in series with a fluid pathway within a hollow rotor shaft of the electric motor.

Example embodiment 39: The drive unit housing of example embodiment 38, the continuous fluid pathway in fluid communication with the fluid pathway within the hollow rotor shaft via a portion of the fluid pathway disposed within the shared wall.

Example embodiment 40: The drive unit of example embodiment 36, the continuous fluid pathway including a spiral pathway disposed about a perimeter of the second housing section to cool the electric motor.