E-MACHINE SYSTEM WITH ROTOR ARRANGEMENT IN FLUID CIRCUIT FOR COOLING AND LUBRICATION

An e-machine system includes a housing and an e-machine. The e-machine system further includes a rotor shaft that is elongate and that extends along an axis between a first end and a second end of the rotor shaft. The e-machine is at least partly supported on the rotor shaft, and the rotor shaft is supported for rotation within the housing about the axis. The system further includes a rotor shaft axial passage that extends through the rotor shaft along the axis. The rotor shaft axial passage defines an inlet extending axially through the first end and a first outlet extending axially through the second end. The rotor shaft includes a radial aperture extending radially out of the rotor shaft. The rotor shaft axial passage is configured to receive a fluid via the inlet and to distribute out the fluid via the first outlet and the radial aperture.

TECHNICAL FIELD

The present disclosure relates, generally, to an e-machine system such as an electric motor system, electric generator system, and the like, and the present disclosure relates, more particularly, to an e-machine system with a rotor arrangement that is in a fluid circuit for cooling and lubrication purposes.

BACKGROUND

E-machines, such as electric motors, electric generators, and combination motor/generators, are provided for a variety of uses. For example, electric traction motors are proposed for electric vehicles, locomotives, and the like.

E-machine systems may generate significant heat during operation, may operate in high-temperature environments, etc. Thus, e-machine systems are proposed that include cooling features. However, providing such cooling features remains challenging. Additionally, some e-machine systems may have moving parts that need lubrication for maintaining proper operation, but this can be difficult too. There may be detrimental increases in costs, part count, device complexity, size, bulkiness, and/or weight if these features are included.

Thus, there remains a need for an e-machine system that provides effective cooling. There also remains a need for an e-machine system that effectively lubricates parts within the system. There remains a need for these e-machine systems, wherein the cooling and/or lubricating features are provided in a relatively compact, low-weight package. There is also a need for such an e-machine system that also provides high manufacturing efficiency for reduced costs and manufacturing time.

BRIEF SUMMARY

In one embodiment, an e-machine system is disclosed that includes a housing and an e-machine housed within the housing. The e-machine system further includes a rotor shaft that is elongate and that extends along an axis between a first end and a second end of the rotor shaft. The e-machine is at least partly supported on the rotor shaft, and the rotor shaft is supported for rotation within the housing about the axis. The system further includes a rotor shaft axial passage that extends through the rotor shaft along the axis. The rotor shaft axial passage defines an inlet extending axially through the first end and a first outlet extending axially through the second end. The rotor shaft includes a radial aperture extending radially out of the rotor shaft. The rotor shaft axial passage is configured to receive a fluid via the inlet and to distribute out the fluid via the first outlet and the radial aperture.

In another embodiment, a method of operating an e-machine system is disclosed that includes providing an e-machine that is housed within a housing. The method also includes providing a rotor shaft that is elongate and that extends along an axis between a first end and a second end of the rotor shaft. The e-machine is at least partly supported on the rotor shaft. The rotor shaft is supported for rotation within the housing about the axis. The rotor shaft includes a rotor shaft axial passage that extends through the rotor shaft along the axis. The rotor shaft axial passage defines an inlet extending axially through the first end and a first outlet extending axially through the second end. The rotor shaft includes a radial aperture extending radially out of the rotor shaft. The rotor shaft axial passage is configured to receive a fluid via the inlet and to distribute out the fluid via the first outlet and the radial aperture. The method further includes circulating a fluid from the inlet to the first outlet and the radial aperture and back to the inlet.

In a further embodiment, an e-machine system is disclosed that includes a housing and an e-machine that is housed within an e-machine housing of the housing. The system also includes a geartrain that is housed within a gearbox housing of the housing. Moreover, the system includes a rotor shaft that is elongate and that extends along an axis between a first end and a second end of the rotor shaft. The e-machine is at least partly supported on the rotor shaft. The rotor shaft is supported for rotation within the housing about the axis. The geartrain is operably coupled to the second end of the rotor shaft. Additionally, a rotor shaft axial passage extends through the rotor shaft along the axis. The rotor shaft axial passage defines an inlet extending axially through the first end and a first outlet extending axially through the second end. The rotor shaft includes a radial aperture extending radially out of the rotor shaft, the rotor shaft axial passage configured to receive a fluid via the inlet and to distribute out the fluid via the first outlet and the radial aperture. The system further includes a fluid circuit configured for flow of a fluid. The fluid circuit includes the rotor shaft axial passage and the radial aperture. The fluid circuit defines a first flow path from the inlet to the first outlet for cooling the rotor shaft. The fluid circuit also defines a second flow path from the inlet to the radial aperture for lubricating at least part of the geartrain.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Thus, any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the present disclosure and not to limit the scope of the present disclosure, which is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

Broadly, example embodiments disclosed herein include an e-machine system with an associated fluid circuit that provides cooling and/or lubrication to the e-machine system. In some embodiments, the e-machine system includes a rotor arrangement that supports an e-machine. The rotor arrangement may include one or more fluid passages, openings, conduits, tubes, apertures, etc. through which a fluid may flow for cooling and/or lubricating the e-machine system. The fluid may flow through a shaft of the rotor arrangement to cool the e-machine, bearings, and/or other features proximate the shaft. The fluid may also flow from the shaft to lubricate one or more features of the e-machine system. For example, a transmission may be operably coupled to the e-machine, and the fluid circuit may route the fluid from the shaft of the rotor arrangement to one or more gear members of the transmission.

In some embodiments, the shaft of the rotor arrangement may include an axial passage that extends from an axial inlet of the shaft to an axial outlet of the shaft. In addition, the rotor arrangement may include one or more radial apertures that are fluidly connected to the axial passage, and which extend radially out of the shaft. The fluid may circulate through the circuit, cooling the rotor arrangement as the fluid moves axially through the shaft, and the fluid may also branch out of the rotor arrangement via the radial apertures for lubricating the gear members of the transmission.

FIG.1is a schematic view of an e-machine system100according to example embodiments of the present disclosure. The e-machine system100may have a variety of configurations. In some embodiments, the e-machine system100may be configured as a traction drive system102that is included, for example, on a vehicle106. Thus, the traction drive system102may be configured for driving one or more wheels104of the vehicle106. More specifically, the wheels104may be included at opposite ends of an axle111, and a chassis107may be supported on the wheels104by a suspension system (not shown). The vehicle106may be an electric car, truck, van, motorcycle, boat, or other vehicle. However, it will be appreciated that the e-machine system100may be configured otherwise without departing from the scope of the present disclosure. It will be appreciated, for example, that the e-machine system100may be configured for driving an input member of a differential, which is operatively attached to the wheels104without departing from the scope of the present disclosure.

Generally, the e-machine system100may include a housing125. The housing125may include an e-machine housing124with a cavity129therein. The e-machine system100may also include an e-machine110that is received in the cavity129and housed within the e-machine housing124.

The e-machine110may be an electric motor112in some embodiments. However, it will be appreciated that the e-machine110may be configured as an electric generator. Furthermore, the e-machine110may be operable in some modes as a motor and in additional modes as a generator. The e-machine110may include a rotor member and a stator member that are housed within the cavity129of the e-machine housing124.

Also, the e-machine system100may include a transmission130. The transmission130may generally include a geartrain132that is housed within a gearbox housing136of the housing125. The gearbox housing136may be attached (e.g., fixed) to a side wall172of the e-machine housing124.

The geartrain132may be of any suitable type. The geartrain132may operatively connect the e-machine110and the axle111and may provide a chosen gear ratio from its input to its output.

The e-machine110may be supported by a rotor arrangement116within the e-machine housing124. The rotor arrangement116is illustrated schematically inFIG.1and is illustrated according to example embodiments inFIGS.2and3. As will be discussed, the rotor arrangement116may include components supported for rotation about an axis109(i.e., rotation axis109) within the e-machine housing124. For example, the rotor arrangement116may at least partly include, define, and/or operatively connect to a rotor shaft126of the e-machine110. The rotor member of the e-machine110may be supported on the rotor shaft126, and the stator member of the e-machine110may be fixed within the e-machine housing124and may surround the rotor member and the rotor shaft126. In embodiments in which the e-machine110is an electric motor112, the rotor shaft126may be referred to as an output rotor shaft126of the electric motor112.

In some embodiments, a shaft engagement member128may be operably supported on the rotor shaft126. The shaft engagement member128may be a gear, a spline, or other feature for operatively attaching to the transmission130. Furthermore, the e-machine110may be coupled to the wheels104via the transmission130. The geartrain132may be attached to the shaft engagement member128and to the axle111. The gearbox housing136and the e-machine housing124may be moveably supported on the axle111by one of more bearings114(e.g., a bearing sleeve, suspension tube, etc.) such that the axle111may rotate relative thereto.

During operation, the electric motor112may rotatably drive the rotor shaft126and the shaft engagement member128supported thereon. This rotational power may transfer to the geartrain132, which may transmit the power to the axle111to rotate the wheels104and propel the vehicle106.

Furthermore, the e-machine system100may include a fluid circuit180. The fluid circuit180may be configured for circulating a fluid, such as a lubricating and/or cooling fluid. The fluid may be a liquid. The fluid may be a lubricant/coolant oil in some embodiments. The fluid may, therefore, be a number of known lubricating oils also used in heat exchanger/cooling systems.

Furthermore, the fluid circuit180may be coupled to the rotor arrangement116as will be discussed. Accordingly, the fluid circuit180and the rotor arrangement116may include features that provide cooling to the rotor arrangement116and to surrounding features of the e-machine system100. Furthermore, the fluid circuit180and the rotor arrangement116may include features that provide lubrication to the shaft engagement member128, the geartrain132, bearing(s), and/or other components of the e-machine system100.

FIG.2shows the rotor arrangement116in additional detail according to example embodiments. As shown, the rotor shaft126may include a shaft member127that is elongate and that may extend along the axis109between a first end141and a second end142. The shaft member127of the rotor shaft126may be a hollow cylinder. The first end141may be supported by a first bearing member143for rotation in the e-machine housing124, and the second end142may be supported for rotation by a second bearing member145within the gearbox housing136. The shaft member127may include an intermediate portion150, which is disposed axially between the first end141and the second end142. The first end141may be stepped downward in diameter from that of the intermediate portion150. The second end142may be similarly stepped downward in diameter.

The first end141may be supported on a first wall member144of the e-machine housing124by the first bearing member143. The first bearing member143may be a rolling element bearing in some embodiments. The first end141may be stepped in diameter in some embodiments to engage with an inner race146of the first bearing member143. The first wall member144may be defined by a cap- or bell-shaped part and may be fixed to other stiff and strong structures of the e-machine housing124. The first wall member144may include a stepped bore148that receives an outer race147of the first bearing member143. The first bearing member143may also include one or more rolling elements149between the inner and outer races146,147.

The intermediate portion150may extend through an aperture170of the side wall172of the e-machine housing124to extend axially out of the e-machine housing124. Thus, the second end142may extend out of the e-machine housing124and may be disposed within the gearbox housing136. The side wall172may include a first face186and a second face188, which face in opposite axial directions. The aperture170may have a first portion190, which may have a substantially constant diameter along its axial length. The aperture170may also have a deflection portion192, which may have a frustoconic taper that widens gradually in diameter as the deflection portion192extends axially from the first portion190. Accordingly, the deflection portion192may be tapered and angled to generally face in an axial direction toward the shaft engagement member128and the gear space184.

The second end142may be supported on a second wall member154by the second bearing member145. The second end142may be stepped in diameter in some embodiments to engage with an inner race156of the second bearing member145. The second wall member154may be a wall of the gear box housing136. The second wall member154may be fixedly attached to the side wall172of the e-machine housing124so as to define a gear space184therebetween. The second wall member154may include a stepped bore158that receives an outer race157of the second bearing member145. The second bearing member145may also include one or more rolling elements159between the inner and outer races156,157.

Furthermore, the shaft engagement member128may be supported on the second end142, within the gear space184of the gear box housing136. As such, the shaft engagement member128may be disposed between the second bearing member145and the wall172along the axis. The shaft engagement member128may be of a variety of types (e.g., a spur gear, a helical gear, a bevel gear, a spline, or other type). The shaft engagement member128, in some embodiments, may be an independent gear that is connected to (e.g., fixed to) the rotor shaft126. In additional embodiments, as represented inFIG.2, the shaft engagement member128may be integrally attached to the rotor shaft126so as to be unitary therewith.

The shaft member127of the rotor shaft126may be hollow to include a passage174that extends from the first end141to the second end142. The passage174may be open at the first end141and the second end142, and the passage174may extend continuously therebetween along the axis109. The passage174may be defined by an inner diameter surface175of the shaft member127. The inner diameter surface175may include an inner step176proximate the second end142.

Additionally, the shaft member127may include at least one radial aperture, such as a first radial aperture138and a second radial aperture139. There may be more or less than two radial apertures138,139. The first and second radial apertures138,139may extend radially from the inner radial surface175to an outer radial surface177of the shaft member127. The first and second radial apertures138,139may be spaced apart in a circumferential direction about the axis109. The first and second radial apertures138,139may be oriented perpendicular to the axis109in some embodiments.

The rotor shaft126may further include a transition tube178. The transition tube178may be hollow and tubular with an inner passage179extending axially therethrough. The transition tube178may include an inner passage179. The transition tube178may include an upstream end182that is frusto-conic, and the transition tube178may include a downstream end183that has a constant diameter. In additional embodiments, the downstream end183may progressively reduce in diameter for jetting fluid therefrom. The upstream end182may be seated against the inner step176of the shaft member127, and the downstream end183may extend and project axially out from the second end142of the shaft member127. The inner passage179may be fluidly connected to the passage174. The inner passage179may taper gradually downward in diameter as the inner passage179extends through the upstream end182toward the downstream end183, and the inner passage179may remain a constant diameter as the inner passage179extends through the downstream end183.

The rotor arrangement116may further include a first end cap194. The first end cap194may be disc-shaped and may be fixedly attached to the first wall member144proximate the first end141of the rotor shaft126. The first end cap194may also include a hollow inlet tube196that projects into the passage174of the rotor shaft126. The inlet tube196may be fixed relative to the first wall member144, and the inlet tube196may be fluidly connected to the passage174. In some embodiments, the rotor arrangement116may include a first seal member198. The first seal member198may be a known sealing feature that is included radially between the inlet tube196and the inner radial surface175of the passage174to define a fluid seal therebetween.

The rotor arrangement116may further include a second seal member200. The second seal member200may be a known seal that is included radially between the intermediate portion150and the inner radial surface defining the first portion190of the aperture170. The second seal member200may define a fluid seal between the cavity129and the gear space184. The second seal member200may be disposed in an axial position that is between the first and second radial apertures138,139and the cavity129.

The rotor arrangement116may additionally include a third seal member197. The third seal member197may be a known seal that is included radially between the downstream end183of the transition tube178and the second wall member154. The third seal member197may define a fluid seal between the exterior of the shaft126and the passage174therein.

The rotor arrangement116may further include a second end cap214. The second end cap214may be disc-shaped and may be fixedly attached to the second wall member154, proximate the second end142of the rotor shaft126. The second end cap214may receive the downstream end183of the transition tube178. The rotor arrangement116may include a fastener, such as a nut202that attaches the downstream end183to the second end cap214. The nut202may be a known fastener.

The fluid circuit180is represented schematically inFIG.2according to example embodiments. The fluid circuit180may include flow structures (tubes, pipes, etc.) that fluidly connect the components discussed herein. The fluid circuit180may be a closed fluid circuit with at least one oil pump301that pumps the fluid therethrough. The fluid circuit180may also include an oil filter302that filters the fluid as it moves therethrough. The fluid circuit180may further include a heat exchanger310, such as a cross-flow radiator system that is supported on the vehicle106. The heat exchanger310may be configured for cooling (i.e., removing heat) from the fluid as it flows therethrough.

As shown inFIG.2, the inlet tube196and, thus, the first end141of the shaft126may be fluidly connected to the fluid circuit180. The inlet tube196and the first end141may define a fluid inlet into the passage174of the rotor arrangement116.

Furthermore, the downstream end183and, thus, the second end142of the rotor shaft126may be fluidly connected to the fluid circuit180. The downstream end183and second end142may extend axially and may define a first outlet from the passage174.

Additionally, the radial apertures138,139may be fluidly connected to the fluid circuit180. The radial apertures138,139may extend radially and may define respective second outlets from the passage174.

The fluid circuit180may additionally include a first outlet branch321, which may include one or more pipes or other fluid conduits. The first outlet branch321may be fluidly connected, at its upstream end, to the end183of the transition tube178at the second end142of the shaft member127. The first outlet branch321may be fluidly connected, at its downstream end, to the gearbox housing136(e.g., to the gearbox oil sump322within the gearbox housing136).

Additionally, the fluid circuit180may include a second outlet branch323. The second outlet branch323may be fluidly connected, at its upstream end, to the radial apertures138,139(i.e., to the second outlet of the rotor shaft126). The second outlet branch323may be fluidly connected, at its downstream end, to the gearbox housing136(e.g., to the gearbox oil sump322within the gearbox housing136).

Moreover, the fluid circuit180may include a return branch324. The return branch324may be fluidly connected, at its upstream end, to the gearbox housing136(e.g., to the gearbox oil sump322within the gearbox housing136). The return branch324may be fluidly connected, at its downstream end, to the inlet tube196at the first end141of the shaft member127.

In some embodiments, the heat exchanger310may be operatively coupled to the fluid circuit180within the first outlet branch321. Thus, the heat exchanger310may be disposed between the first outlet (i.e., the end183at the second end142) and the gearbox housing136in a flow direction through the first outlet branch321. Furthermore, the oil pump301and oil filter302may be operatively coupled to the fluid circuit180within the return branch324.

Accordingly, during operation of the e-machine110, the fluid circuit180may circulate fluid through the rotor shaft126of the rotor arrangement116. The fluid may receive heat from the e-machine110via the shaft member127to maintain operating temperatures of the e-machine110relatively low. The tapered shape of the transition tube178may regulate pressure, mitigate pressure drop, and/or maintain desirable flow pressure. Furthermore, some of the fluid may exit from the transition tube178to be cooled by the heat exchanger310, while the remaining fluid may exit via the radial apertures138,139to lubricate the shaft engagement member128and/or the gear train132. The radial apertures138,139may also regulate flow, mitigate pressure drop, and/or maintain desirable flow of the fluid. Fluid that may be flowing axially away from the shaft engagement member128may be re-directed in the opposite axial direction by the deflection portion192due to its beveled shape. The second seal member200may further inhibit backflow into the e-machine housing124. Flows from the first and second outlet branches321,323may merge back at the gearbox oil sump322. From there, the fluid may flow to the oil pump301and oil filter302before being re-circulated back to the inlet tube196and the first end141of the passage174.

The rotor arrangement1116and fluid circuit1180are shown inFIG.3according to additional example embodiments. The rotor arrangement1116and fluid circuit1180may be substantially similar to the embodiments ofFIG.2except as noted. Features that correspond to those ofFIG.2are indicated with corresponding reference numbers increased by 1000. Description of those components will not be repeated for the sake of brevity.

As shown, the rotor shaft1126may be substantially the same as the embodiments ofFIG.2. The fluid circuit1180may include and fluidly connect the oil pump1301, the oil filter1302, the gearbox oil sump1322. However, the heat exchanger1310may be fluidly connected to the return branch1324as shown inFIG.3. In other words, the heat exchanger1310may be operatively coupled to the fluid circuit1180and disposed downstream of the gearbox housing1124in a flow direction through the fluid circuit1180. Thus, fluid from the first outlet branch1321may flow directly to the gearbox oil sump1322, fluid from the second outlet branch1323may flow to the gear train1132before flowing to the gearbox oil sump1322, and these flows may merge before flowing to the heat exchanger1310in the return branch1324. Additional arrangements of the fluid circuit are envisioned as well. For example, the fluid circuit1180may include the oil filter1302upstream of the oil pump1301in some embodiments.

Furthermore, as shown inFIG.3, the rotor arrangement1116may include a bearing1326(i.e., a third bearing, a motor housing bearing). The bearing1326may be a rolling element bearing that is supported between the shaft1126and the side wall1172. The second seal member1200may be axially disposed between the bearing1326and the second outlet branch1323to seal the bearing1326against the coolant flow.

Accordingly, the e-machine systems100of the present disclosure may provide effective cooling. Furthermore, the e-machine systems100of the present disclosure may provide lubrication to the geartrain and/or other moving parts. These features may also be provided in a compact, low-weight package. Additionally, the e-machine systems100of the present disclosure may have a relatively low part count, may be manufactured efficiently for reduced manufacturing costs and time.

As used herein, the term “axial” refers to a direction that is generally parallel to or coincident with an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder or disc with a centerline and generally circular ends or opposing faces, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends or faces. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally parallel to or coincident with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane of a cylinder or disc that is perpendicular to the centerline or axis. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms “axial” and “radial” (and any derivatives) may encompass directional relationships that are other than precisely aligned with (e.g., oblique to) the true axial and radial dimensions, provided the relationship is predominantly in the respective nominal axial or radial direction. As used herein, the term “substantially” denotes within 5% to account for manufacturing tolerances. Also, as used herein, the term “about” denotes within 5% to account for manufacturing tolerances.