Patent Publication Number: US-11028873-B2

Title: Shaft assembly for an electrified vehicle and shaft providing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 15/382,854, which was filed on 19 Dec. 2016 and is now U.S. Pat. No. 10,352,351. U.S. patent application Ser. No. 15/382,854 is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to a shaft assembly for a motor and, more particularly, to a shaft assembly incorporating an insert that provides a fluid conduit through the motor shaft assembly. 
     BACKGROUND 
     Electrified vehicles differ from conventional motor vehicles because, among other things, electrified vehicles are selectively driven using one or more electric machines powered by a traction battery. The electric machines can drive the electrified vehicles instead of, or in addition to, an internal combustion engine. Example electrified vehicles include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles (FCVs), and battery electric vehicles (BEVs). 
     The traction battery can be used to selectively power the electric machines and other electrical loads of the electrified vehicle. The traction battery includes a plurality of interconnected battery cells that store energy for powering these electrical loads. Components of the electrified machines contribute to the overall weight of the electrified vehicle. The electrified machines can require thermal management and lubrication. 
     SUMMARY 
     An electrified vehicle assembly according to an exemplary aspect of the present disclosure includes, among other things, an outer shaft that is rotatable about an axis. The outer shaft rotatably couples a motor of an electrified vehicle to a transmission component of the electrified vehicle. A shaft insert provides a conduit for a fluid and that blocks the fluid from flowing radially between the shaft insert and the outer shaft relative to the axis. The shaft insert includes a polymer-based material, a composite material, or both. 
     In another example of the foregoing electrified vehicle assembly, the shaft insert is slideably received within the outer shaft. 
     In another example of any of the foregoing electrified vehicle assemblies, the shaft insert is formed within the outer shaft. 
     In another example of any of the foregoing electrified vehicle assemblies, portions of the shaft insert are radially spaced from the outer shaft to provide at least one annular cavity between the shaft insert and the outer shaft relative to the axis. 
     In another example of any of the foregoing electrified vehicle assemblies, the shaft insert extends axially from a first end portion to an opposite, second end portion. The first and second end portions are radially enlarged relative to other portions of the shaft insert to provide an annular cavity between the shaft insert and the outer shaft. The annular cavity is axially between the first and second end portions. 
     In another example of any of the foregoing electrified vehicle assemblies, a material composition of the shaft insert has a lower density than a material composition of the outer shaft. 
     In another example of any of the foregoing electrified vehicle assemblies, the insert is sealed against the outer shaft. 
     Another example of any of the foregoing electrified vehicle assemblies includes the transmission component and the motor. 
     Another example of any of the foregoing electrified vehicle assemblies includes at least one vehicle drive wheel. The motor is configured to rotate the shaft to drive the at least one vehicle drive wheel through the transmission component. 
     In another example of any of the foregoing electrified vehicle assemblies, the outer shaft is a metal or metal alloy, and the shaft insert is a polymer-based material, a composite material, or both. 
     A electrified vehicle shaft providing method according to another exemplary aspect of the present disclosure includes, among other things, positioning a shaft insert within an outer shaft. The shaft insert has a fluid conduit and is configured to block fluid from communicating radially between the shaft insert and the outer shaft. The shaft insert includes a polymer-based material, a composite material, or both. The method further includes rotatably coupling together a motor of an electrified vehicle to a transmission component of an electrified vehicle using the outer shaft. 
     Another example of the foregoing method includes inserting the shaft insert as a molded component into the outer shaft. 
     Another example of any of the foregoing methods includes molding the shaft insert within outer shaft. 
     Another example of any of the foregoing methods radially spacing portions of the shaft insert from the outer shaft to provide at least one annular cavity between the shaft insert and the outer shaft relative to the axis. 
     Another example of any of the foregoing methods driving the transmission component with the outer shaft to drive at least one vehicle drive wheel of the electrified vehicle. 
     Another example of any of the foregoing methods rotating the outer shaft to drive the transmission component, and driving the motor to rotate the outer shaft. 
     In another example of any of the foregoing methods, the shaft insert extends axially from a first end portion to an opposite, second end portion, wherein the first and second end portions are radially enlarged relative to other portions of the shaft insert to provide an annular cavity between the shaft insert and the outer shaft, the annular cavity axially between the first and second end portions. 
     In another example of any of the foregoing methods, the outer shaft is a metal or metal alloy. Further, the shaft insert is a polymer-based material, a composite material, or both. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: 
         FIG. 1  illustrates a schematic view of an example powertrain for an electrified vehicle. 
         FIG. 2  illustrates a perspective view of a motor from the powertrain of  FIG. 1 . 
         FIG. 3  illustrates a side view of a portion of the motor of  FIG. 3  with a stator of the motor sectioned to show a rotor of the motor. 
         FIG. 4  illustrates a section view at Line  4 - 4  in  FIG. 3  of a shaft assembly of the motor. 
         FIG. 5  illustrates a section view at line  5 - 5  in  FIG. 4  of the shaft assembly of the motor. 
         FIG. 6  illustrates a step in an assembling method for the shaft assembly of  FIG. 4 . 
         FIG. 7  illustrates a section view of a shaft for the motor of  FIG. 2  according to another exemplary embodiment. 
         FIG. 8  illustrates a step in an assembling method for the shaft assembly of  FIG. 7 . 
         FIG. 9  illustrates a shaft assembly for use in the motor of  FIG. 2  according to yet another exemplary embodiment. 
         FIG. 10  illustrates a shaft assembly for use in the motor of  FIG. 2  according to yet another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure is directed toward a shaft assembly for a motor. The shaft assembly incorporates an insert. The insert reduces an overall weight of the shaft assembly. The insert includes a conduit used to communicate a fluid through the shaft assembly. These and other features are discussed in greater detail in the following paragraphs of this detailed description. 
       FIG. 1  schematically illustrates a powertrain  10  for an electrified vehicle. Although depicted as a hybrid electric vehicle (HEV), it should be understood that the concepts described herein are not limited to HEVs and could extend to any other types of conventional vehicles and electrified vehicle, including, but not limited to, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), etc. 
     The powertrain  10  of the example electrified vehicle includes a battery pack  14  having a plurality of battery arrays  18 , an internal combustion engine  20 , a motor  22 , and a generator  24 . The motor  22  and the generator  24  are types of electric machines. The motor  22  and generator  24  may be separate or have the form of a combined motor-generator. This motor  22 , the generator  24 , or both, can be part of a transmission for the electrified vehicle. Passageways for communicating a fluid through portions of the motor  22 , the generator  24 , or both, can facilitate meeting lubrication and thermal management requirements for the motor  22 , the generator  24 , bearings of the motor  22  and the generator  24 , and other components associated with the transmission. 
     In this embodiment, the powertrain  10  is a power-split powertrain that employs a first drive system and a second drive system. The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels  28 . The first drive system includes a combination of the engine  20  and the generator  24 . The second drive system includes at least the motor  22 , the generator  24 , and the battery pack  14 . The motor  22  and the generator  24  are portions of an electric drive system of the powertrain  10 . 
     The engine  20  and the generator  24  can be connected through a power transfer unit  30 , such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, can be used to connect the engine  20  to the generator  24 . In one non-limiting embodiment, the power transfer unit  30  is a planetary gear set that includes a ring gear  32 , a sun gear  34 , and a carrier assembly  36 . 
     The generator  24  can be driven by the engine  20  through the power transfer unit  30  to convert kinetic energy to electrical energy. The generator  24  can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft  38  connected to the power transfer unit  30 . 
     The ring gear  32  of the power transfer unit  30  is connected to a shaft  40 , which is connected to the vehicle drive wheels  28  through a second power transfer unit  44 . The second power transfer unit  44  may include a gear set having a plurality of gears  46 . Other power transfer units could be used in other examples. 
     The gears  46  transfer torque from the engine  20  to a differential  48  to ultimately provide traction to the vehicle drive wheels  28 . The differential  48  may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels  28 . In this example, the second power transfer unit  44  is mechanically coupled to an axle  50  through the differential  48  to distribute torque to the vehicle drive wheels  28 . 
     The motor  22  can be selectively employed to drive the vehicle drive wheels  28  by outputting torque to a power transfer unit shaft  52  that is connected to the second power transfer unit  44 . In this embodiment, the motor  22  and the generator  24  cooperate as part of a regenerative braking system in which both the motor  22  and the generator  24  can be employed as motors to output torque. For example, the motor  22  and the generator  24  can each output electrical power to recharge cells of the battery pack  14 . 
     Referring now to  FIGS. 2 to 5  with continuing reference to  FIG. 1 , the motor  22  includes a motor shaft assembly  60 , a rotor  64 , a stator  68 , and a housing  70 . The motor shaft assembly  60  is connected to the power transfer unit shaft  52 . The rotor  64  is disposed within the stator  68 . Portions of the motor shaft assembly  60 , the rotor  64 , and the stator  68  are housed within the housing  70 . 
     Power from the battery pack  14 , or from some other source, energizes the stator  68 , which rotates the rotor  64  to rotate the shaft assembly  60  about an axis A. Rotation of the shaft assembly  60  rotates the power transfer unit shaft  52  to drive the second power transfer unit  44 . 
     The rotor  64 , in this example, comprises stacks of individual laminations secured to the shaft assembly  60 . The laminations are steel in this example. The laminations could be compressed axially between a nut  72  and a radial flange  74  of the shaft assembly  60 . 
     Increasing an outer diameter D R  of the rotor  64  can increase a torque generated by the rotor  64  and the shaft assembly  60 . Increasing the diameter D R  of the rotor  64  can require increasing a diameter D s  of the shaft assembly  60 . Packaging requirements could also require decreasing an axial length of the shaft, which can lead to an increase in the diameter D R . 
     In an exemplary non-limiting embodiment, the shaft assembly  60  includes an insert  76 , an outer shaft  80 , and a retention ring  82 . The insert  76  is made of a material weighing less than a material of the outer shaft  80 . The insert provides a fluid conduit  84 . The insert  76  reduces an overall weight of the shaft assembly  60  when compared to a similarly sized shaft assembly that lacks any insert and provides a similarly sized fluid conduit with an outer shaft. Notably, density of the insert  76  is less than a density of the outer shaft  80 . 
     The insert  76  is received within the outer shaft  80  of the shaft assembly  60 . The retention ring  82  can prevent movement of the insert  76  relative to the outer shaft  80  and, as will be explained, provide an opening  90  and a support surface. 
     The insert  76  provides a fluid conduit  84 . Thus, the shaft assembly  60  is considered a hollow shaft assembly. Notably, the fluid conduit  84  has a perimeter  86  provided entirely by the insert  76 . That is, the fluid conduit  84  does not extend radially between the insert  76  and the outer shaft  80  such that a portion of the perimeter  86  would be provided by the outer shaft  80 . 
     Fluid, such as a cooling fluid, a lubricating fluid, or both, can move from a fluid supply  88  to the fluid conduit  84  of the insert  76 . The fluid, for example, can be used to control thermal energy levels of the motor  22  and, optionally, other components. The fluid could instead or additionally be used to lubricate components of the motor  22  and, optionally, other components. 
     In this exemplary embodiment, fluid moves along a path P through the opening port  90  in the retention ring  82  to the fluid conduit  84 . The retention ring  82  provides a sealing interface with the fluid supply  88 . The rejection ring  82  can, for example, seal against a fluid input port from the fluid supply with an o-ring type seal. 
     The retention ring  82  can be a metal, or metal alloy. In a specific embodiment, the retention ring  82  is an aluminum. The retention ring  82  can be press-fit into the outer shaft  80 . 
     A first portion of the fluid that has entered the fluid conduit  84  flows through a portion of the fluid conduit  84  and then flows radially along paths PR from the fluid conduit  84 . The fluid exiting the fluid conduit  84  along the radial paths PR flows along radial passageways  92  extending through the insert  76  and the outer shaft  80 . Fluid flowing along the paths PR can be used to, for example, cool the laminations of the rotor  64 , to cool the stator  68 , or to lubricate components that move relative to each other. The example shaft assembly  60  includes two radial passageways  92  circumferentially distributed about the axis A. 
     A second, remaining, portion of the fluid that has entered the fluid conduit  84  flows along the entire axial length of the fluid conduit  84  and then flows along an axial path P A  from the fluid conduit  84 . The fluid exiting the fluid conduit  84  along the axial path P A  flows along an axial passageway  94  in the power transfer unit shaft  52 . The fluid exiting the fluid conduit  84  along the axial path P A  could also flow along an interface between the outer shaft  80  of the shaft assembly  60  and the power transfer unit shaft  52 . Fluid exiting the fluid conduit  84  along the axial path P A  could, for example, cool the power transfer unit shaft  52  and support structure associated with the shaft assembly  60  or the power transfer unit shaft  52 , such as bearings. Fluid exiting the fluid conduit  84  along the axial path P A  could instead, or additionally be used to lubricate components that move relative to each other. 
     The example insert  76  is a polymer-based material, such as a resin material or a plastic material. The insert  76  could, for example, be a thermoset resin or a molded plastic, like nylon. In some examples, the insert  76  is a composite material, which could include a fibrous material. A composite material could instead, or additionally, be a material filled with additives, such as microballoons, or including pockets of injected air to facilitate decreasing a density of the insert  76 . The example outer shaft  80  is a metal or metal alloy. The example retention ring  82  is aluminum or steel. The insert  76  effectively takes the place of heavier, metallic-based material. Utilizing the insert  76  can thus reduce an overall weight of the shaft assembly when compared to shaft assemblies without an insert. 
     Notably, a radially outer perimeter of the insert  76  contacts the outer shaft  80  along an entire axial length of the insert  76 . While the insert  76  could be completely removed, and the area occupied by the insert  76  left open to reduce a weight of the shaft assembly  60 , this approach would not provide the fluid conduit  84  having a relatively small cross-sectional diameter. That is, if the insert  76  were completely removed from the shaft assembly  60 , fluid would need to additionally fill the area occupied by the insert  76 . Much more fluid would then be required and fluid pressure could not be as closely controlled. Further, the fluid would be inhibited from flowing smoothly through the shaft assembly  60  since the relatively small cross-sectional diameter of the fluid conduit  84  within the insert  76  promotes a smooth flow of the fluid. 
     The retention ring  82  can provide a support surface for the shaft assembly  60 . The support surface could interface with supportive bearings, for example. Providing the support surface with the retention ring  82  makes the support surface less prone to wear than if the insert  76  provided the support surface. 
     Further, the retention ring  82 , which is made of a harder material than the insert  76  will avoid at least some wearing of a seal associated with the fluid inlet port from the fluid supply  88 . That is, the seal could wear more quickly if the seal were interfacing with the insert  76  rather than the retention ring  82   
     Referring to  FIG. 6 , with continuing reference to  FIG. 5 , the insert  76  can be formed within the outer shaft  80  of the shaft assembly  60 . In the examples of this disclosure, the insert  76  is shown as a single monolithic structure. The insert  76  could instead be provided by a plurality of separate insert portions. 
     When forming the insert  76  within the outer shaft  80 , molten material from a material supply  89  is injected into a cavity C provided between the outer shaft  80  of the shaft assembly  60  and a die pin  96 . The molten material within the cavity C cures to provide the insert  76 . 
     Once cured, the die pin  96  is withdrawn axially along a direction W. The area formerly occupied by the die pin  96  establishes the fluid conduit  84  within the insert  76 . 
     The radial passageways  92  can be formed with a drilling process, for example. Alternatively, the radial passageways  92  could be provided by forming the molten material around pins extending radially through the outer shaft  80  into the cavity C. 
     After the insert  76  is formed, the retention ring  82  is inserted into the outer shaft  80  of the shaft assembly  60 . 
     In this disclosure, like reference numbers designate like elements where appropriate and reference numerals with the addition of 100 of multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding original elements. 
     Referring now to  FIGS. 7 and 8 , a shaft assembly  160  according to another exemplary embodiment includes an insert  176  held within an outer shaft  180 . The insert  176  provides a fluid conduit  184 . 
     Assembling the shaft assembly  160  involves sliding the insert  176  along the rotational axis A of the shaft assembly  160  into the outer shaft  180  from the position of  FIG. 8  to the position of  FIG. 7 . A retention ring  182  is then inserted into the outer shaft  180  to hold the insert  176  within the outer shaft  180  and to, optionally, provide a support surface for the shaft assembly  160 . 
     Notably, the insert  176  can be formed independently from the outer shaft  180  and formed prior to insertion within the outer shaft  180 . Forming the insert  176  independently from the outer shaft  180  can permit the insert  176  to incorporate more varied geometries as the final geometry is not constrained to the shape of the cavity C ( FIG. 6 ). A density of the insert  176  is less than a density of the outer shaft  180 . 
     Like the insert  76  of the embodiment of  FIGS. 4 to 6 , the insert  176  can be formed from a polymer-based material, such as a resin material or a plastic material. The insert  176  could, for example, be a thermoset resin or a molded plastic, like nylon. In some examples, the insert  176  is a composite material, which could include a fibrous material. A composite material could instead, or additionally, be a material filled with additives, such as microballoons, or including pockets of injected air to facilitate decreasing a density of the insert  176 . The insert  176  reduces an overall weight of the shaft assembly  160  when compared to a shaft assembly occupying the area of the insert  176  with a metal or metal alloy. 
     The insert  176  is formed to provide an annular channel  98  about a periphery of the insert  176 . As shown, the example insert  176  extends axially from a first end portion  99 A to an opposite, second end portion  99 B. The first and second end portions  99 A,  99 B are radially enlarged relative to other portions of the shaft insert  176  to provide the annular channel  98  between the shaft insert and the outer shaft, the annular channel  98  axially between the first and second end portions  99 A,  99 B. When the insert  176  is positioned within the outer shaft  180  as shown in  FIG. 7 , the annular channel  98  is positioned radially between a portion of the insert  176  and a portion of the outer shaft  180 . The annular channel  98  is an open area where the radially outer perimeter of the insert  176  is spaced from the outer shaft  280 . The open area of the annular channel  98  is separated from the fluid conduit  184  by portions of the insert  176  such that fluid flowing in the fluid conduit  184  does not enter the open area of the annular channel  98 . 
     The annular channel  98  can reduce an amount of material required to provide the shaft assembly  160 , and additionally reduce an overall weight of the shaft assembly  160  when compared to a shaft assembly that fills the area of the annular channel  98  with a material. 
     Referring now to  FIG. 9 , yet another example shaft assembly  260  includes an insert  276  received within an outer shaft  280  of the shaft assembly  260 . A density of the insert  276  is less than a density of the outer shaft  280 . Like the insert  76  of the embodiment of  FIGS. 4 to 6 , the insert  276  can be formed from a polymer-based material, such as a resin material or a plastic material. The insert  276  could, for example, be a thermoset resin or a molded plastic, like nylon. In some examples, the insert  276  is a composite material, which could include a fibrous material. A composite material could instead, or additionally, be a material filled with additives, such as microballoons, or including pockets of injected air to facilitate decreasing a density of the insert  276 . The insert  276  reduces an overall weight of the shaft assembly  260  when compared to a shaft assembly occupying the area of the insert  276  with a metal or metal alloy. The insert  276  provides a fluid conduit  284 . 
     The shaft assembly  260  includes two annular channels  298   a  and  298   b  separated by a radially extending rib  99  of the insert  276 . The rib  99  directly contacts the outer shaft  280  of the shaft assembly  260 . The rib  99  is a single rib in this example. In other examples, the rib  99  could be one of a series of one or more separate ribs. The annular channels  298   a  and  298   b  are open areas where the radially outer perimeter of the insert  276  is spaced from the outer shaft  280 . The open area of the annular channels  298   a  and  298   b  are separated from the fluid conduit  184  by portions of the insert  276  such that fluid flowing in the fluid conduit  284  does not enter the open area of the annular channels  298   a  and  298   b.    
     The rib  99  can facilitate supporting the insert  276  within the outer shaft  280  such that the areas of the insert  276  providing the annular channels  298   a  and  298   b  do not flex radially relative to the outer shaft  280 . The rib  99 , or ribs, can prevent significant radially outward deflections of the insert  276  under high centrifugal forces when the shaft assembly  260  is rotating at relatively high speeds. 
     Referring now to  FIG. 10 , yet another example shaft assembly  360  includes an insert  376  received within an outer shaft  380  of a shaft assembly  360 . The insert  376 , in this exemplary embodiment, is a tube of a metal or metal alloy. The insert  376  provides a fluid conduit  384 . 
     The insert  376  is formed to provide an annular channel  398  about a periphery of the insert  376 . When the insert  376  is positioned within the outer shaft  380  as shown in  FIG. 10 , the annular channel  398  is positioned radially between a portion of the insert  376  and a portion of the outer shaft  380 . The annular channel  398  is an open area where the radially outer perimeter of the insert  376  is spaced from the outer shaft  380 . The open area of the annular channel  398  is separated from the fluid conduit  384  by portions of the insert  376  such that fluid flowing in the fluid conduit  384  does not enter the open area of the annular channel  398 . 
     The annular channel  398  can reduce an amount of material required to provide the shaft assembly  360 , and additionally reduce an overall weight of the shaft assembly  360  when compared to a shaft assembly that fills the area of the annular channel  398  with a material. 
     Areas B where the insert  376  contacts the outer shaft  380  can include an adhesive to bond the insert  376  to the outer shaft  380  and to seal the annular channel  398  from fluid moved through the fluid conduit  384  provided by the insert  376 . The insert  376  could instead, or additionally, be crimped or mechanically secured to the outer shaft  380 . In such cases a seal, like an o-rings or a polymer/adhesive seal, could be used to seal the annular channel  398  from fluid moved through the fluid conduit  384 . 
     A feature of the disclosed embodiments can include incorporating an insert into a shaft assembly to provide a fluid conduit and to reduce an overall weight of the shaft assembly. In some examples, the insert can reduce a weight of a shaft assembly by up to 25 percent when compared to a shaft assembly lacks an insert and provides a fluid conduit with an outer shaft. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.